Although practical, structured training in ventilation is described as an important but limited part of critical-care education, opportunities to undertake such training remain restricted. The study therefore evaluated a course designed to combine theoretical instruction with simulation-based practice in managing acute respiratory failure. Because the sample was small and the reported evaluation covered immediate course outcomes, the findings cannot establish whether the gains were sustained or transferred to clinical practice.

Before the intervention, all 17 residents completed a questionnaire containing a standardized 15-item multiple-choice examination. They were subsequently assigned to one of two educational groups: group A received theory-based classes only, while group B received theory-based classes plus practice-based simulation. Skill was assessed through the examination rather than through direct observation of residents managing patients in intensive care, making the measured outcome an assessment of knowledge and skills associated with the course.

The simulation component consisted of four scenarios involving acute exacerbations of chronic lung disease. Residents practiced using high-flow nasal oxygen, non-invasive ventilation and mechanical ventilation under simulated conditions. Following the intervention, skill-assessment scores increased in all three respiratory modalities in group B, which combined classes with simulation.

In group A, increases were reported for high-flow nasal oxygen and non-invasive ventilation, while no increase was reported for mechanical ventilation. Scores did not differ between the three ventilation modalities at baseline or after the intervention. At baseline, senior residents had higher scores than junior residents; after training, higher scores were observed among both senior and junior residents in group B, but among senior residents only in group A.

Course satisfaction was also high. Both junior and senior residents reported gains in confidence and perceived competence, although these were self-reported experiences and were not accompanied by evidence of improved patient outcomes. The results are consistent with the course’s stated aim of strengthening residents’ ability to manage ventilatory support for acute respiratory failure, but the assessment does not establish that the training altered treatment decisions, reduced clinical delays or improved the care received by critically ill patients.

Nor did the study determine whether the score increases remained after participants returned to clinical work or whether the same approach would be useful for other members of the care team. Overall, the study provides measured support for adding structured simulation to respiratory intensive care education. Its clearest finding is that residents who received both theory and practice recorded post-course assessment gains across all three ventilation modalities, while the classroom-only group recorded gains in two.

The authors identified long-term retention, transfer to clinical practice and inter-professional applications as important questions for future work. Until those issues are addressed, the results should be viewed as evidence of immediate assessment gains from a combined ventilation course rather than proof of superior training, durable competence or better patient outcomes.

Subject of Research: Evaluation of a simulation-based ventilation training course for pulmonology residents in respiratory intensive care.

Article Title: Impact of a simulation-based ventilation training course for respiratory intensive care residents

Article References: Artaud-Macari, E., Fresnel, E., Kerfourn, A., Melone, M.-A., Mazellier, N., Roger, P.-A., Lebret, M., Cuvelier, A., Girault, C., Médrinal, C., & Salaün, M. (2026). Impact of a simulation-based ventilation training course for respiratory intensive care residents. BMC Medical Education. https://doi.org/10.1186/s12909-026-10046-8

Image Credits: AI Generated

DOI: 10.1186/s12909-026-10046-8

Keywords: simulation-based medical education, pulmonology residents, respiratory intensive care, acute respiratory failure, mechanical ventilation, non-invasive ventilation, high-flow nasal oxygen, clinical skills training, medical education, Impact, simulation-based, ventilation

The core problem is the leak. Unlike invasive ventilation, where the breathing circuit is sealed around an endotracheal tube, non-invasive ventilation deliberately allows air to escape through vents in the mask and, unintentionally, through gaps around the face. Those leaks wreak havoc on the ventilator’s basic assumptions. Flow sensors misread how much air is actually entering the lungs, triggering mechanisms fire late or fire when the patient has not made any effort at all, and the machine may keep pushing air into a breath the patient has already abandoned. In a landmark multicenter study of patients receiving non-invasive ventilation for acute respiratory failure, severe patient-ventilator asynchrony, defined as an asynchrony index above ten percent, occurred in forty-three percent of patients, and the magnitude of the leak correlated directly with wasted breathing efforts and delayed cycling. Every wasted effort represents work the patient performs that the machine fails to assist, and over hours it can mean the difference between recovery and exhaustion.

Engineers have responded with what the review calls the first practical closed loops. Modern ventilators embed leak-compensation algorithms that continuously estimate how much of the measured flow is escaping and adjust trigger sensitivity and cycling thresholds accordingly. Bench studies by Vignaux and colleagues showed that leaks impair intensive care ventilator performance by increasing trigger delay and reducing pressurization, and that non-invasive ventilation modes only partially corrected these defects, with performance varying widely between devices. A later randomized crossover study found that these algorithms reduced leak-related asynchronies but sometimes introduced new ones, such as premature cycling that cuts breaths short. Carteaux and colleagues demonstrated that dedicated non-invasive ventilation ventilators achieved lower asynchrony indices than general intensive care units machines, largely because they handled leaks and auto-triggering better. The lesson, the authors stress, is a fundamental principle of control engineering applied to physiology: an algorithm that fixes one form of desynchronization can create another if it does not understand the whole breathing pattern.

The most sophisticated feedback signal now being exploited is the patient’s own neural command to breathe. Neurally adjusted ventilatory assist, or NAVA, uses a specialized feeding tube with electrodes to measure the electrical activity of the diaphragm, known as EAdi, and delivers pressure in proportion to that signal. Because the trigger and cycling are driven by the diaphragm itself rather than by airflow through a leaky mask, NAVA is largely immune to the leak problem. Physiological studies by Piquilloud and Longhini showed improved patient-ventilator interaction and comfort during masked ventilation. But the randomized trial evidence is more cautious: in adults with de novo acute respiratory failure, NAVA reduced asynchrony and ventilation-related complications without reducing ventilation failure or twenty-eight-day mortality compared with conventional pressure support. In chronic obstructive pulmonary disease exacerbations, NAVA and adaptive support ventilation performed similarly, though the latter required fewer clinician adjustments. A 2026 feasibility trial of adaptive support ventilation with the IntelliSync waveform module found greater patient comfort and shorter hospital stays, with a numerically lower but statistically insignificant failure rate, leaving larger trials awaited.

Between the simple leak compensators and the neural systems sits a family of adaptive pressure modes that are already in widespread clinical use. Average volume-assured pressure support, or AVAPS, and its cousin iVAPS automatically titrate the inspiratory pressure within preset limits to hit a target tidal volume or alveolar ventilation, and some devices can even auto-adjust the expiratory pressure. These are genuine feedback loops, but narrow ones: they respond to delivered volume, not to the patient’s effort, comfort, or trajectory toward failure. The most recent evidence, a 2026 systematic review and meta-analysis by Gregory and colleagues covering eleven comparative studies, found that AVAPS was associated with a lower risk of intubation than standard bilevel ventilation in acute hypercapnic respiratory failure, without a clear mortality benefit. The authors of the review urge restraint in interpreting that result, noting that only three studies contributed complete intubation data, the evidence mixed randomized and observational designs, and the populations were dominated by COPD patients. AVAPS, they conclude, is a pressure-adaptation loop, not a fully closed-loop therapy.

Perhaps the most striking gap the review identifies is that no current system measures the thing that matters most: whether the patient’s breathing muscles are being adequately unloaded or silently injured. Persistent high respiratory drive and excessive inspiratory effort can fatigue the diaphragm, strain the cardiovascular system, and even cause what researchers call patient self-inflicted lung injury, where powerful spontaneous breaths stretch delicate tissue. A pivotal study by Tonelli and colleagues found that the relief of inspiratory effort, measured with an esophageal pressure catheter within the first two hours of non-invasive ventilation, was an early and accurate predictor of whether the treatment would succeed. That finding connects physiology directly to a life-or-death decision: whether the mask is truly resting the patient or merely postponing an inevitable intubation. The review argues that future controllers should evolve from synchrony loops into injury-avoidance loops, using esophageal pressure, airway occlusion pressure, diaphragm electrical activity, and ultrasound to keep unloading in a safe window.

Artificial intelligence promises to knit these fragments together, but the review is candid about how far away that remains. Machine learning models applied to ventilator waveforms and electronic health records are exquisitely sensitive to how data are prepared: sampling frequency, aggregation windows, prediction horizons, and missing-data handling all determine what physiology a model can actually learn, and a breath-by-breath signal is not interchangeable with a thirty-minute trend. Three research lines stand out. A newly peer-reviewed ontology for non-invasive respiratory support aims to standardize concepts across devices and records, enabling interoperability and rule-based reasoning. Computational leak estimation is improving the reconstruction of true patient flow, a prerequisite for any advanced control. And safety-oriented offline reinforcement learning combined with digital twin verification, proposed by Yu and colleagues, could allow ventilator control policies to be stress-tested in simulation before ever touching a patient, though that work remains preclinical and not specific to non-invasive ventilation.

The invasive ventilation literature offers both encouragement and a warning. A 2024 systematic review found that closed-loop systems can improve process measures and reduce staff workload, and the large randomized ACTiVE trial showed that the multivariable INTELLiVENT-ASV system improved ventilation quality and reduced severe gas-exchange derangements. Yet patients on the automated system did not spend more days free from the ventilator than those managed with protocolized conventional care. Better automation, in other words, does not automatically become better outcomes. That caution weighs heavily on non-invasive ventilation, where treatment failure is not a single control error but a clinical judgment involving gas exchange, mental status, hemodynamics, secretion burden, and airway protection, and where delayed intubation remains a central mechanism of harm.

The authors’ prescription is a hierarchical, multirate architecture with the clinician firmly in command. Fast breath-to-breath loops would handle leak estimation, triggering, and cycling; intermediate loops would regulate ventilation and muscle unloading; and a slower supervisory layer would integrate gas exchange, comfort, and failure risk, sometimes issuing not a ventilator adjustment but a recommendation to change the interface or proceed to intubation. Such systems would need bounded rates of change, fail-safe fallback modes, transparent disclosure of which signal triggered any action, and rigorous external validation. The evidence, the review concludes, supports the physiological rationale for closed-loop non-invasive ventilation but not autonomous operation or a proven major outcome benefit. Until prospective trials show that supervised, safety-constrained automation improves results without delaying escalation, the smartest machine at the bedside will remain the one with a trained intensivist behind it.

Subject of Research: Closed-loop and adaptive control strategies for non-invasive ventilation in critically ill adults

Article Title: Closed-loop non-invasive ventilation in critical care: current evidence and clinical perspectives

Article References: Guimaraes, F. S., & Esquinas, A. M. (2026). Closed-loop non-invasive ventilation in critical care: current evidence and clinical perspectives. Frontiers in Anesthesiology, 5, Article 1948602. https://doi.org/10.3389/fanes.2026.1948602

Image Credits: AI Generated

DOI: 10.3389/fanes.2026.1948602

Keywords: non-invasive ventilation, closed-loop ventilation, critical care, patient-ventilator asynchrony, NAVA, AVAPS, leak compensation, respiratory drive, artificial intelligence, waveform analysis, ventilator weaning, intensive care

The research team, led by Lara Benning and Esther Irene Schwarz of the University Hospital Zurich, registered the project on PROSPERO and followed the Meta-analyses Of Observational Studies in Epidemiology checklist. They searched PubMed from 1977 through late 2025, screened titles, abstracts and full texts with two independent reviewers, and applied strict inclusion criteria: studies had to involve individuals with Duchenne muscular dystrophy specifically, report appropriate survival data such as median survival or age at death, and be published in English. Cohorts published more than once contributed only their earliest and most comprehensive dataset. The final pool comprised 44 retrospective and 9 prospective studies, most conducted in Europe, North America and Asia, with a median follow-up of about eight years and a median patient age of just over 14 years.

Statistically, the challenge was considerable, because most studies reported median survival without confidence intervals or interquartile ranges. The authors therefore conducted a meta-analysis of means, first verifying that the underlying distributions showed negligible skewness so that medians could reasonably stand in for means. Standard errors were derived from interquartile ranges using the Wan and colleagues approximation, from 95 percent confidence intervals using the Cochrane Handbook formula, or imputed from sample-size-weighted median standard errors where nothing else was available. For studies that published only Kaplan-Meier survival curves, median survival was reconstructed using a method described by Broomfield and colleagues. Between-study heterogeneity was estimated with restricted maximum likelihood, confidence intervals were adjusted with the Hartung-Knapp method, and random-effects models weighted each study by inverse variance.

The headline numbers are striking. Across all included studies, pooled median survival was 23.9 years. But when the investigators split the evidence by ventilation status, a deep divide appeared. In the 16 studies that included no ventilated patients, pooled median survival was 19.0 years, with a 95 percent confidence interval of 18.2 to 19.7 years and moderate heterogeneity. In the 33 studies that included ventilated patients, pooled median survival reached 28.9 years, with a confidence interval of 27.0 to 30.7 years, though heterogeneity here was extreme, with an I-squared statistic of 98.2 percent. Meta-regression confirmed the pattern quantitatively: each percentage-point increase in the proportion of ventilated patients within a study was associated with a measurable gain in median survival, and ventilation status alone explained roughly 64 percent of the between-study variation.

Equally important is what the cumulative meta-analysis revealed about time itself. When studies were ordered chronologically and the pooled estimate was recalculated with each new addition, median survival rose progressively in both ventilated and non-ventilated cohorts. Stratified by era, median survival moved from 18.8 years in cohorts from around 1980 or earlier, to 22.2 years by around 1990, 25.1 years by around 2000, and 28 years by around 2010, holding at 27.1 years in the most recent period. The trajectory means that a boy diagnosed today, with access to comprehensive care, can reasonably expect to live into his late twenties or thirties, and some patients in well-resourced settings are now reported to survive into their forties and beyond.

The analysis also delivered a nuanced verdict on drug therapy. Glucocorticoids, the anti-inflammatory steroids long used to preserve ambulation and upper limb function in children with Duchenne muscular dystrophy, showed no significant association with survival in the meta-regression, whether or not the analysis was adjusted for study period. In contrast, heart failure medications emerged as powerful predictors of longevity. Treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers was significantly associated with longer median survival, explaining about 70 percent of between-study variation, and beta-blockers showed a similar association, though the authors caution that the beta-blocker finding rested on only six studies. All results remained consistent after adjustment for study period, and sensitivity analyses using alternative period classifications produced the same conclusions.

Perhaps the most consequential shift documented in the analysis concerns why patients die. In the earliest era, respiratory failure accounted for roughly 91.5 percent of deaths, the expected consequence of progressive diaphragm and intercostal muscle weakness. By the period around 1990, cardiac causes had risen to 57.1 percent of deaths, and in the most recent era other causes, including lower respiratory tract infections, gastrointestinal complications and adverse events related to anesthesia and surgery, contributed 45.7 percent. The overall median age at death climbed from 18.6 years in the earliest period to the mid-twenties in recent cohorts. In other words, ventilation has not merely extended life; it has rewritten the disease’s terminal chapter, transferring the burden of mortality from the lungs to the heart and to a widening spectrum of secondary complications.

That shift carries direct clinical implications. Progressive cardiomyopathy is now a major determinant of mortality, and a reduced left ventricular ejection fraction independently predicts earlier death, yet patients with Duchenne muscular dystrophy remain frequently undertreated for heart failure. Part of the problem is diagnostic: the standard New York Heart Association classification of heart failure relies on dyspnea and exercise intolerance, symptoms that skeletal muscle weakness confounds in non-ambulatory patients, so cardiac decline can be under-recognized until late. Current guidelines recommend starting ACE inhibitor or ARB therapy in late childhood, and prophylactic treatment has been linked to a survival benefit. The new meta-regression findings reinforce that recommendation, suggesting that early cardioprotective pharmacotherapy is one of the few modifiable factors clearly tied to longer life in this population.

The authors are candid about the limitations of their work. Assigning birth cohorts to periods was occasionally difficult because patients within single studies were born across wide intervals, and some studies had follow-up too short for death to occur or enrolled predominantly pediatric populations. Only about 38 percent of the pooled patients were deceased at the time of reporting, and mean age at death does not account for censoring. There is also the possibility of immortal-time bias in ventilated cohorts, since patients must survive long enough to receive ventilation. Incomplete reporting precluded detailed analyses of body mass index, glucocorticoid dosing, cough assist devices, scoliosis surgery and geographic variation, all of which may contribute to the pronounced heterogeneity. The team recommends that future studies report restricted mean survival time, the area under the Kaplan-Meier curve, as a more robust measure of average survival.

What emerges from the full picture is a disease transformed by systems of care rather than by any single drug. Non-invasive ventilation delivered through a nasal or facial mask, typically initiated around age twenty based on sleep studies and pulmonary function tests, marked the transformative step, and the analysis found no significant survival difference between non-invasive and invasive ventilation modalities, meaning patients can choose the approach that best preserves their quality of life. Forced vital capacity below one liter remains a strong negative predictor of mortality, and starting home ventilation slows the decline of lung function. But survival now depends equally on proactive cardiac surveillance, early heart failure management, and genuinely multidisciplinary teams spanning respiratory medicine, cardiology, neurology, rehabilitation, gastroenterology, nutrition, palliative care and mental health. Persistent disparities in outcomes across regions and healthcare systems suggest that the next frontier in Duchenne muscular dystrophy is not a molecule but equitable access to the care model that has already proven it can add a decade of life.

Subject of Research: Temporal trends in survival and causes of death in Duchenne muscular dystrophy

Article Title: Improving survival in Duchenne muscular dystrophy across eras: a systematic review and cumulative meta-analysis

Article References: Benning, L., Bousraou, Z., Gruber, B., Ulrich, S., & Schwarz, E. I. (2026). Improving survival in Duchenne muscular dystrophy across eras: a systematic review and cumulative meta-analysis. Journal of Neurology, 273(10), Article 564. https://doi.org/10.1007/s00415-026-14121-4

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14121-4

Keywords: Duchenne muscular dystrophy, survival, home mechanical ventilation, meta-analysis, cardiomyopathy, heart failure therapy, non-invasive ventilation, life expectancy, causes of death, glucocorticoids, dystrophin, multidisciplinary care

The research, led by José Castro and Mamede de Carvalho at the Hospital de Santa Maria and the Universidade de Lisboa, drew on one of the largest single-centre ALS cohorts ever assembled for this purpose: 1,486 patients contributing 2,968 serial phrenic nerve conduction studies. In this test, a small electrical stimulus is applied over the nerve in the neck, and electrodes record the compound muscle action potential, the summed electrical response of the diaphragm. Because the diaphragm cannot voluntarily influence the evoked signal, the amplitude is, by design, effort-independent. The investigators expressed each amplitude as a percentage of an age- and sex-predicted normative value and asked a deceptively simple question: does this number forecast when a patient will need breathing support, above and beyond the established clinical measures?

The answer, delivered through a pre-registered analysis plan lodged publicly on the Open Science Framework, was emphatic. Using cause-specific Cox proportional hazards models with death treated as a competing risk, the team found that each 10 percent decrease in predicted phrenic amplitude was associated with a 22 percent higher hazard of starting non-invasive ventilation, with an adjusted hazard ratio of 1.22 and a 95 percent confidence interval of 1.16 to 1.27. The statistical weight of the association was extraordinary: a likelihood-ratio chi-square of 77.6, corresponding to a p-value of roughly ten to the minus eighteenth. In a field where biomarker candidates routinely collapse on replication, a signal of this magnitude in nearly three thousand serial measurements commands attention.

Perhaps the most clinically useful finding is the temporal structure of the prediction. The association was concentrated in the near term: within the first year of follow-up, the hazard ratio climbed to 1.31 per 10 percent decrement, before attenuating in later intervals. This makes physiological sense. The phrenic compound muscle action potential reflects the number and integrity of functioning motor units in the diaphragm, so a low or rapidly falling amplitude signals that the respiratory motor pool is approaching a functional threshold. Once that threshold is crossed, ventilatory decline accelerates. For clinicians, the message is that the nerve test is not a distant oracle but a near-term alarm, precisely the window in which the timing of ventilation matters most for survival and quality of life.

The quantitative gains over existing practice were substantial. Adding phrenic amplitude to a clinical model built on forced vital capacity and the revised ALS Functional Rating Scale, the standard severity instrument that incorporates respiratory items, improved discrimination by an optimism-corrected increment of 0.055, with a bootstrap-validated confidence interval of 0.034 to 0.073. That may sound modest, but in prognostic modelling, where incremental improvements of this size are considered meaningful, it represents a genuine advance. More striking is the absolute risk translation: patients whose phrenic amplitude fell below the age- and sex-adjusted normal threshold had approximately double the twelve-month risk of requiring ventilation, 62 percent versus 29 percent. A single bedside-adjacent measurement effectively stratifies patients into two very different futures.

To capture the dynamic nature of the disease, the team also deployed a Bayesian joint longitudinal-survival model, a sophisticated statistical architecture that links repeated measurements over time to the hazard of the clinical event. This analysis separated two distinct prognostic signals: the current amplitude itself, carrying a hazard ratio of 1.57 per 10 percent decrement, and the rate of decline of that amplitude, carrying an independent hazard ratio of 1.30. In other words, both where the diaphragm’s electrical output stands today and how fast it is eroding contribute independent information. This dual signal mirrors the logic clinicians apply intuitively to forced vital capacity, but here it operates on a measurement that no amount of weakness elsewhere in the body can distort.

The problem the study solves is well documented in the ALS literature. Forced vital capacity depends on bulbar competence to seal the mouthpiece, on respiratory muscle strength to generate flow, and on cognitive capacity to follow instructions. Slow vital capacity has been proposed as a gentler alternative, and supine measurements add sensitivity to diaphragmatic weakness, but all remain effort-dependent to some degree. Recent work from the same Lisbon group showed that cognitive dysfunction is associated with an underestimation of respiratory function on these tests, meaning the very patients whose breathing is deteriorating may appear deceptively stable. Guidelines from the European Academy of Neurology and its predecessors have long acknowledged the difficulty of timing ventilation, and the randomised trial by Bourke and colleagues that established the survival benefit of non-invasive ventilation relied on thresholds that cooperative patients can demonstrate but severely affected ones cannot.

The phrenic nerve conduction study itself is not new. It has been studied as a prognostic marker in ALS since at least 2009, when Pinto, Turkman and colleagues showed its value in predicting respiratory insufficiency, and the Lisbon group has since published normative data establishing age- and sex-referenced amplitude thresholds. What distinguishes the new work is scale, rigour and statistical ambition. The pre-registered plan, the competing-risk framework, the bootstrap validation, the time-dependent discrimination analyses and the joint modelling collectively meet the standards set by the TRIPOD reporting guidelines for clinical prediction models. The authors also positioned the measurement as a candidate outcome for clinical trials, where an objective, effort-independent readout of respiratory motor unit loss could serve as a sensitive endpoint for drugs targeting motor neuron degeneration.

Important caveats remain, and the authors state them plainly. The cohort is single-centre, and although it is large, the amplitude values were expressed against normative data derived from the same investigative tradition, raising the possibility of centre-specific calibration. External validation in independent cohorts, ideally spanning different health systems and ethnicities, is required before the marker can be embedded in guidelines, and the models will need recalibration to local populations. The association also attenuates beyond the first year, so the marker complements rather than replaces longitudinal clinical assessment. And while the test involves a mild electrical stimulus that most patients tolerate well, it is still an invasive neurophysiological procedure compared with a spirometry manoeuvre, which shapes how it might be deployed in routine monitoring.

Even with those qualifications, the implications are considerable. Respiratory failure remains the dominant cause of death in ALS, and the window for initiating ventilation comfortably, with time for adjustment, education and psychological preparation, is narrow and easy to miss when the usual yardsticks falter. An effort-independent electrical signature of the diaphragm’s remaining motor units, measured in a clinic room in minutes, that roughly doubles the predicted twelve-month risk when abnormal, offers a way to keep that window open for the patients who need it most, including those who can no longer perform the breathing manoeuvres their own care depends on. As disease-modifying therapies multiply and trials search for responsive endpoints, the humble phrenic nerve, stimulated and recorded for decades in neurophysiology labs, may be poised to become one of the most consequential numbers on the ALS chart.

Subject of Research: Phrenic nerve conduction studies as prognostic biomarkers of respiratory failure in amyotrophic lateral sclerosis

Article Title: Phrenic nerve amplitude as an effort-independent prognostic biomarker of respiratory failure in amyotrophic lateral sclerosis

Article References: Castro, J., Sá, V., Lopes, D., Alves, I., Oliveira Santos, M., & de Carvalho, M. (2026). Phrenic nerve amplitude as an effort-independent prognostic biomarker of respiratory failure in amyotrophic lateral sclerosis. Journal of Neurology, 273(10), Article 574. https://doi.org/10.1007/s00415-026-14125-0

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14125-0

Keywords: amyotrophic lateral sclerosis, phrenic nerve, nerve conduction studies, non-invasive ventilation, respiratory failure, prognosis, biomarkers, forced vital capacity, diaphragm, neurophysiology, motor neuron disease, ALSFRS-R

The central tension the authors describe is physiological rather than technological. Positive airway pressure can recruit collapsed alveoli and raise lung volumes, improving oxygenation through positive end-expiratory pressure, or PEEP. In patients with hydrostatic pulmonary edema and left ventricular failure, PEEP may even improve cardiac output by reducing both afterload and preload. But in ARDS, respiratory drive is often markedly increased, fueled by cortical and peripheral inputs, mechanoreceptor stimulation, and inflammatory mediators. The result can be excessive spontaneous breathing effort, generating large negative pleural pressure swings, elevated transpulmonary pressures, and amplified regional lung stress. This phenomenon, known as patient self-inflicted lung injury, or P-SILI, can promote overdistension and the same barotrauma, volutrauma, and atelectrauma classically associated with ventilator-induced lung injury—particularly in the reduced, non-uniform ‘baby lung’ that characterizes ARDS.

The evidence linking injurious effort to outcomes is concrete. In acute hypoxemic respiratory failure, persistent high inspiratory effort under non-invasive ventilation, measured by esophageal pressure swings, has been shown to predict non-invasive ventilation failure. Large tidal volumes above 9 milliliters per kilogram of predicted body weight—reflecting the combination of delivered pressure support and strong patient effort—have likewise been associated with poor outcomes. Despite this, standardized bedside assessment of inspiratory effort, particularly using esophageal pressure monitoring, remains limited and is not routinely implemented in intensive care units. The authors argue that this monitoring gap is one of the key obstacles to using non-invasive support safely, because clinicians currently lack a reliable, widely available way to distinguish patients whose spontaneous breathing is helping them from those whose breathing is injuring them.

Interface choice matters enormously in this calculus. Helmet non-invasive ventilation enables delivery of higher PEEP levels with minimal air leaks, and patient-ventilator asynchronies are generally less clinically relevant than with face masks. Even when a patient’s inspiratory effort fails to trigger pressure support, the patient continues to perform genuine inspiratory work by drawing airflow and volume from the helmet—true work of breathing rather than an isometric effort. Intriguingly, the helmet’s longer trigger delays and less efficient pressurization may induce desynchronization that limits excessive transpulmonary pressure swings and potentially enhances lung protection. The trade-off is monitoring: tracking tidal volumes through a helmet remains challenging, and the interface can provoke claustrophobia. Face masks, by contrast, struggle to maintain a seal in edentulous patients, those with beards, or individuals with nasogastric tubes.

The clinical evidence for non-invasive ventilation and CPAP in ARDS remains inconsistent and highly dependent on disease severity. Some studies and subgroup analyses suggest these modalities may be feasible in carefully selected patients with mild ARDS who lack hemodynamic instability and retain preserved mental status, potentially avoiding intubation. Helmet-delivered non-invasive ventilation was specifically found to reduce intubation compared with high-flow nasal cannula in patients with COVID-19. Ongoing randomized trials—including HENIVOT-2, HighCPAP, and HONOUR—are expected to clarify the role of these approaches further. In the meantime, the authors outline reasonable starting settings: PEEP of approximately 5 centimeters of water, up to 10, with pressure support of 5 to 8 centimeters of water above PEEP, rapidly titrated according to comfort, effort, tidal volume, and gas exchange. Patients with persistent hypoxemia may require higher PEEP of 8 to 12 centimeters of water via helmet.

High-flow nasal cannula occupies a different niche. Delivering heated, humidified oxygen at 30 to 60 liters per minute, it reduces nasopharyngeal dead space, generates a modest PEEP effect through resistance to expiratory flow, and limits entrainment of ambient air, producing more stable alveolar oxygen delivery. These effects decrease work of breathing compared with standard oxygen, reflected in reduced respiratory rate, less dyspnea, and improved comfort. Compared with non-invasive ventilation, however, it provides lower PEEP and less homogeneous tidal volume distribution, as assessed by electrical impedance tomography. Its practical advantages are considerable: it imposes no uncomfortable interface, does not require sedation, and allows patients to remain awake, eat, speak, and undergo prone positioning.

The trial evidence favors high-flow therapy as a first-line strategy for moderate disease. Randomized trials in acute hypoxemic respiratory failure report lower intubation rates compared with conventional oxygen or non-invasive ventilation, particularly in patients with a PaO2/FiO2 ratio below 200 millimeters of mercury, although the effect on mortality remains uncertain. Current guidelines, including French consensus recommendations developed by the DELPHI method, recommend high-flow nasal cannula as first-line oxygen therapy in acute hypoxemic respiratory failure at that severity threshold. Typical initiation involves flows of 40 to 60 liters per minute, commonly 50, with the fraction of inspired oxygen adjusted to maintain target saturation and flow subsequently tuned to the patient’s inspiratory demand and work of breathing. The authors conclude that high-flow therapy should be considered first-line non-invasive support for most patients with moderate ARDS, provided close physiologic reassessment identifies failure early enough to avoid delayed intubation.

Deciding between a non-invasive trial and immediate intubation rests on a defined set of red flags. Severe hypoxemia, hemodynamic instability, additional organ failure such as renal failure or delirium, impending cardiac or respiratory arrest, coma, inability to protect the airway, a large secretion burden, or poor tolerance of interfaces should all prompt consideration of upfront intubation. When none of these is present, clinicians should assess the severity of hypoxemia alongside respiratory drive and inspiratory effort. Marked accessory muscle use and persistent signs of high work of breathing signal P-SILI risk. A reasonable sequence is a trial of high-flow nasal cannula with rapid reassessment of oxygenation, respiratory rate, and accessory muscle response, escalating to non-invasive ventilation if symptoms persist—while vigilantly avoiding high tidal volumes. Hypercapnia or respiratory acidosis may favor non-invasive ventilation with pressure support, but should also lower the threshold for intubation if it worsens.

Timing of intubation is the field’s most persistent dilemma. Delayed intubation has been identified as a risk factor for mortality in several studies, yet no trial has directly compared intubation versus no intubation in acute hypoxemic respiratory failure. Instead, randomized studies have used prespecified intubation criteria without demonstrating differences in time to intubation across oxygenation strategies. The French consensus identifies cardiac or respiratory arrest from hypoxemia and persistent hypoxemia despite maximal oxygen strategy—PaO2/FiO2 below 60 millimeters of mercury or oxygen saturation below 88 percent—as major criteria for intubation, alongside shock, worsening respiratory failure with tachypnea above 30 breaths per minute, recurrent desaturation, respiratory acidosis, or declining consciousness. The ROX index, which divides the ratio of oxygen saturation to inspired oxygen fraction by respiratory rate, is the best-validated bedside tool for predicting high-flow therapy failure and should complement, rather than replace, clinical judgment.

Awake prone positioning, widely adopted during the COVID-19 pandemic as an adjunct to high-flow therapy or non-invasive ventilation, adds another physiological lever. By improving ventilation-perfusion matching, promoting dorsal recruitment, and reducing dependent atelectasis, it reduced intubation rates when adherence was successfully achieved, though no mortality benefit was demonstrated. For non-COVID ARDS, the physiological rationale is plausible but the evidence remains insufficient. The review’s overarching message is that no single device should be applied for a fixed duration; instead, matching must be individualized to a patient’s evolving physiology. Non-invasive supports are valuable early in ARDS, but their safe use depends on careful selection, close physiologic monitoring, and timely recognition of failure. The next frontier, the authors argue, lies in phenotype-driven strategies and objective markers of injurious respiratory effort that can guide escalation decisions with far greater precision than today’s clinical gestalt.

Subject of Research: Physiology-guided use of non-invasive respiratory support, including high-flow nasal cannula and non-invasive ventilation, in acute respiratory distress syndrome

Article Title: Non-invasive respiratory supports in ARDS: Physiology-guided use, pitfalls, and pathways to success

Article References: Munshi, L., Antonelli, M., & Frat, J.-P. (2026). Non-invasive respiratory supports in ARDS: Physiology-guided use, pitfalls, and pathways to success. Intensive Care Medicine. https://doi.org/10.1007/s00134-026-08616-x

Image Credits: AI Generated

DOI: 10.1007/s00134-026-08616-x

Keywords: ARDS, non-invasive ventilation, high-flow nasal cannula, CPAP, P-SILI, PEEP, helmet ventilation, intubation, ROX index, acute hypoxemic respiratory failure, awake prone positioning, critical care

The study, led by Jorge Luis Alvarado-Socarras together with Delia Edith Theurel-Martin and Edgar Fabián Manrique-Hernández, set out to answer a deceptively simple question: what happens when babies with prenatally predicted mild congenital diaphragmatic hernia are allowed to breathe spontaneously at birth, with intubation reserved only for those who deteriorate? The idea behind this so-called spontaneous breathing approach is not reckless. Advances in prenatal imaging now allow specialists to estimate, before delivery, how severe the lung compression is likely to be, using measures such as the lung-to-head ratio and the position of the liver. Babies whose findings fall into the mildest category might, in theory, manage without immediate mechanical ventilation, avoiding the potential harms of unnecessary tubes, sedation, and ventilator-induced lung injury.

To test what the existing literature actually supports, the team searched five major databases: PubMed/MEDLINE, Embase, Scopus, LILACS, and SciELO, covering the entire period from the inception of each database. The initial search was performed on November 27, 2024, and was subsequently updated through August 8, 2026. Two reviewers independently screened the records, a standard safeguard against selection bias, and the risk of bias in each included study was assessed according to its design. The certainty of the body of evidence was then graded using GRADE, the widely used framework that rates confidence in findings from high to very low. Because the available studies differed so much clinically and methodologically, the authors chose a narrative synthesis rather than pooling numbers into a single statistical estimate, a decision that reflects the fragmented nature of the evidence base.

What emerged from that search was strikingly thin. Only three observational studies qualified for inclusion, and together they described just 30 neonates who were initially managed with a spontaneous breathing approach rather than routine intubation. That is an extraordinarily small foundation for a question that touches the opening minutes of life for hundreds of babies each year. Observational studies, moreover, cannot randomize treatment; they simply report what happened in the centers that chose to try the gentler strategy, which means that selection of which babies received it may have been influenced by factors the studies did not fully capture.

The headline numbers from the review are sobering for advocates of selective intubation. Of the 30 neonates managed initially on spontaneous breathing, 16, or 53.3 percent, required unplanned intubation before surgery because of respiratory deterioration. The remaining 14 babies, 46.7 percent, avoided an unplanned pre-operative intubation and presumably proceeded toward surgical repair without the tube that guidelines would have placed at birth. In other words, in the pooled experience of these three studies, slightly more than half of the babies selected for the gentler approach ended up needing urgent intubation anyway, precisely the outcome the routine-intubation policy is designed to prevent or at least anticipate in a controlled manner.

On the question of survival, the picture is more encouraging but far from definitive. No deaths were reported in the included cohorts, which is a genuinely reassuring signal for a condition that remains one of the most challenging in neonatal intensive care. However, the authors flag an important caveat: in one of the studies, subgroup-specific survival to discharge could not be independently confirmed because the denominator reporting was incomplete. Without knowing exactly how many babies were in the spontaneous breathing subgroup, readers cannot verify what proportion survived. Adverse events and the use of extracorporeal membrane oxygenation, the heart-lung bypass technology reserved for the most severe cases, were uncommon across the included studies, but the authors are explicit that reporting limitations preclude definitive conclusions about safety or survival.

These nuances matter because the stakes of getting the decision wrong are asymmetric. A baby who is intubated unnecessarily may be exposed to complications of airway instrumentation and ventilation, but those risks are generally manageable in an experienced neonatal intensive care unit. A baby who is left breathing spontaneously and then deteriorates rapidly faces a race against time, with a compressed lung that may collapse further as swallowed air distends the herniated bowel. The physiological logic of immediate intubation is that it converts an unpredictable emergency into a controlled procedure performed by a prepared team, often in the delivery room, before the baby’s condition can spiral. The review’s finding that more than half of the selected babies deteriorated underscores how difficult it remains to predict, even with modern prenatal imaging, which newborns will truly tolerate spontaneous breathing.

The certainty assessment by GRADE delivers the review’s central verdict: the available evidence on spontaneous breathing in prenatally predicted mild congenital diaphragmatic hernia is of very low certainty and is insufficient to establish safety or effectiveness relative to routine intubation. Very low certainty means that the true effect could be substantially different from what these small observational studies suggest, and that any future evidence could easily change the conclusion. Three studies and 30 babies, drawn from centers that self-selected into trying the approach, simply cannot carry the weight of overturning a guideline that has protected newborns for generations. The authors are unambiguous in their conclusion: given the substantial heterogeneity and small sample sizes, routine intubation remains the standard of care.

That conclusion does not render the review pointless. On the contrary, it performs a valuable service by mapping the boundaries of current knowledge and exposing how little high-quality evidence underpins any attempt to individualize delivery-room management for this condition. The authors call for further prospective, standardized research before any clinical recommendation can be made, and the shape of that research is fairly clear from their analysis. A well-designed prospective study would need to define in advance which prenatal criteria qualify a baby as mild, standardize the criteria for rescue intubation, and follow outcomes with complete denominator reporting so that survival and complication rates can be calculated without ambiguity. Ideally, such work would be multicenter, because a condition as uncommon as congenital diaphragmatic hernia means that any single unit would need years to accumulate a meaningful number of patients.

For clinicians and expectant parents navigating a prenatal diagnosis today, the practical message is continuity rather than change. Prenatal imaging can identify babies likely to have mild disease, and that information is valuable for counseling, delivery planning, and ensuring that surgery and extracorporeal support are available if needed. But the delivery-room default should remain immediate endotracheal intubation, because the alternative has not been shown to be safe and, in the small published experience, led to urgent intubation in a majority of cases. The review also highlights a broader lesson for neonatology: practices that feel intuitively gentler, including non-invasive ventilation and spontaneous breathing strategies that have transformed care in other contexts such as preterm respiratory distress, cannot simply be transplanted to a condition with unique anatomy without rigorous testing. Until such testing is done, the tube goes in first, and the science of when it can safely wait remains an open question that the next generation of studies will need to answer.

Subject of Research: Non-routine intubation versus spontaneous breathing at birth in neonates with prenatally diagnosed mild congenital diaphragmatic hernia

Article Title: Non-routine intubation in prenatally diagnosed neonates with mild congenital diaphragmatic hernia: a systematic review

Article References: Alvarado-Socarras, J. L., Theurel-Martin, D. E., & Manrique-Hernández, E. F. (2026). Non-routine intubation in prenatally diagnosed neonates with mild congenital diaphragmatic hernia: a systematic review. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07800-8

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07800-8

Keywords: congenital diaphragmatic hernia, prenatal diagnosis, neonatal intubation, spontaneous breathing approach, systematic review, neonatology, ventilation, non-invasive ventilation, GRADE certainty of evidence, neonatal outcomes, delivery room stabilization, BMC Pediatrics

The research, led by Vanessa Campes Dannenberg and Maria L. Castro-Codesal of the University of Alberta, together with colleagues at the Hospital for Sick Children in Toronto and the Alberta Children’s Hospital in Calgary, examined the medical records of 115 children and young people with neuromuscular disorders who were recommended for home non-invasive ventilation, or NIV, between 2010 and 2023. Most of the participants were male, with a median age of 11.8 years at the time of ventilation initiation. The most common diagnoses were Duchenne muscular dystrophy, accounting for 39 percent of the cohort, congenital muscular dystrophies at 19 percent, and spinal muscular atrophy at 14 percent. Nearly every child in the study carried at least one additional chronic condition, with a median of four comorbidities per patient, underscoring how medically complex this population is.

The central question was deceptively simple: when three different sets of polysomnography-based criteria are applied to the same overnight sleep study, do they identify the same children as needing breathing support? The team compared the 2023 guidelines from the American College of Chest Physicians, known as CHEST, against the traditional American Academy of Sleep Medicine, or AASM, definitions of moderate-to-severe obstructive sleep apnea and nocturnal hypoventilation, and against a new set of REM-related criteria proposed by the authors themselves. The CHEST criteria, drawn from a European Respiratory Society statement on pediatric long-term ventilation, flag children whose end-tidal or transcutaneous carbon dioxide exceeds 50 mmHg for at least 2 percent of total sleep time, or rises by 10 mmHg above their waking baseline, or whose oxygen saturation drops below 90 percent for at least 2 percent of sleep time or five continuous minutes.

Those thresholds matter because they are far more sensitive than the older AASM definitions, which require carbon dioxide to exceed 50 mmHg for a full 25 percent of total sleep time before labeling a child as hypoventilating. The results were striking. Only 9 percent of the children met the AASM-based hypoventilation criterion, while the CHEST guidelines identified 25 percent, and the REM-related criteria caught 12 percent. For nocturnal hypoxemia, for which the AASM framework offers no initiation criterion at all, the CHEST guidelines identified 22 percent of the cohort and the REM-related criteria 15 percent. In total, 71 percent of the children met at least one NIV initiation criterion across the three criteria sets, but a meaningful minority were visible only through the newer lenses.

Agreement between the criteria sets, measured with kappa statistics, told a nuanced story. Overall agreement between the CHEST and REM-related criteria was moderate, with a kappa of 0.71, and agreement on nocturnal hypoxemia between those two sets was similarly moderate at 0.69. The strongest agreement, a kappa of 0.86, emerged between the CHEST and AASM criteria on the apnea-hypopnea index, which is unsurprising given that both frameworks use similar thresholds of five or more respiratory events per hour. The divergence, in other words, was not about counting apneas and hypopneas. It was about the slow, silent buildup of carbon dioxide and the dips in oxygen that occur without any discrete respiratory event, particularly during the muscle atonia of REM sleep.

That physiology is the heart of the study’s argument. In children with neuromuscular weakness, breathing during REM sleep depends heavily on the diaphragm, because the intercostal and upper airway muscles lose their tone in that stage. When the diaphragm is also weak, carbon dioxide accumulates and oxygen levels fall, often without producing a single scored apnea. As the disease progresses, these abnormalities spread into non-REM sleep and eventually into wakefulness, culminating in chronic respiratory failure. The authors’ proposed REM-related criteria were designed to capture this earliest phase, and the analysis showed that an additional 11 percent of children met REM-related indications that the AASM-based criteria missed entirely. Thirteen percent of the cohort, twelve children, met no AASM-based criteria at all but satisfied at least one CHEST and one REM-related criterion.

The study also looked at what happened after ventilation began. Ninety-six percent of the children, 111 in total, successfully started NIV, and 73 percent of them sustained the therapy for six to twelve months, the window the researchers chose to avoid the acclimatization period when adherence is typically unstable. Adherence was respectable: children used the machine for a median of six hours per night, and on a median of 60 percent of nights they managed more than four hours of use. Clinician-documented reports from routine visits described improvements in general health in 34 percent of children, better sleep quality in 36 percent, and improved breathing during sleep in 25 percent. Most children avoided emergency department visits, ward admissions, and intensive care during the follow-up period.

Notably, the study found no significant differences in lung function before and after NIV initiation in any of the criteria groups, and no differences in adherence or clinical outcomes between groups. The authors attribute this largely to the substantial overlap among the three groups, since most children met the apnea-hypopnea thresholds common to all criteria sets. They also caution that NIV does not reverse the decline in lung function driven by the underlying disease; at best, it slows the trajectory, and changes are influenced by disease-modifying therapies and the natural history of each disorder. Only about half of the cohort could perform lung function testing that met American Thoracic Society technical standards, further limiting those comparisons.

The findings carry real weight for clinical practice. Earlier work in children with Duchenne muscular dystrophy had already suggested that disease-specific criteria could prompt ventilation for an additional 22 percent of children compared with standard AASM definitions. This study extends that insight to a broader neuromuscular population and adds a physiological rationale: many children show REM-related hypoventilation or hypoxemia with a normal apnea-hypopnea index, and the CHEST guidelines, by lowering the carbon dioxide threshold and adding an explicit hypoxemia criterion, are built to detect exactly that pattern. This matters especially for conditions such as myotonic dystrophy, in which discrete respiratory events are less common but carbon dioxide retention can still be dangerous.

The researchers acknowledge the limits of their retrospective design, their reliance on chart documentation, and the overlap that prevented subgroup comparisons. They also note that future studies may be difficult to conduct, because withholding ventilation until advanced hypoventilation develops would now be ethically questionable. Still, their conclusion is clear and forward-looking: guidelines for children with neuromuscular disease should integrate disease-specific and sleep-stage-specific polysomnographic criteria, watching REM sleep closely for the first signs of failure. Caught early, supported by a mask and a machine at home, these children may avoid the steepest part of the respiratory decline that has long defined their prognosis.

Subject of Research: Polysomnographic criteria for initiating non-invasive ventilation in children with neuromuscular diseases

Article Title: Establishing polysomnographic criteria for initiation of non-invasive ventilation in children with neuromuscular diseases

Article References: Dannenberg, V. C., Amin, R., Anagnostopoulos, G., Adeleye, A., Bendiak, G. N., Kolski, H., & Castro-Codesal, M. L. (2026). Establishing polysomnographic criteria for initiation of non-invasive ventilation in children with neuromuscular diseases. Journal of Clinical Sleep Medicine, 22(1), Article 117. https://doi.org/10.1007/s44470-026-00102-x

Image Credits: AI Generated

DOI: 10.1007/s44470-026-00102-x

Keywords: neuromuscular disease, non-invasive ventilation, polysomnography, REM sleep, sleep-disordered breathing, nocturnal hypoventilation, Duchenne muscular dystrophy, spinal muscular atrophy, pediatric sleep medicine, CHEST guidelines, AASM criteria, nocturnal hypoxemia

The letter responds to a study by Dannenberg and colleagues, published earlier in the same journal, that set out to establish polysomnographic criteria for starting non-invasive ventilation in children with neuromuscular disease. That original investigation addressed a genuine gap. For decades, clinicians have relied on a patchwork of guidelines, expert consensus, and institutional habit when interpreting sleep studies in this population, and the thresholds used to declare a sleep study abnormal have varied widely between centers. Any serious attempt to standardize those thresholds therefore deserves attention, and the letter writers acknowledge the value of the effort even as they probe its foundations.

Polysomnography, the overnight sleep test at the center of this debate, records a remarkable array of physiological signals: brain electrical activity through electroencephalography, eye movements that mark rapid eye movement sleep, muscle tone at the chin and limbs, airflow at the nose and mouth, respiratory effort through chest and abdominal belts, and blood oxygen saturation through pulse oximetry, alongside carbon dioxide measurement where available. In healthy children, breathing during sleep is remarkably stable, particularly in non-REM stages. In children with weakened respiratory muscles, however, the physiology changes in characteristic ways, and understanding those changes is essential to understanding why the criteria debate matters so much.

The key vulnerability lies in REM sleep. During REM, the body’s skeletal muscles, with the exception of the diaphragm and the extraocular muscles, lose their tone as part of the brainstem’s protective mechanism that prevents sleepers from acting out dreams. In a child whose intercostal muscles and accessory breathing muscles are already weakened by conditions such as Duchenne muscular dystrophy or spinal muscular atrophy, this REM-related muscle atonia can leave the diaphragm working alone against the resistance of a floppy chest wall. The result is shallow, inefficient breathing confined to REM periods, with oxygen saturation drifting downward and carbon dioxide accumulating, often without any dramatic apneas to catch an automated scoring algorithm’s attention. This pattern, sometimes called REM-related hypoventilation, is typically the earliest sleep-breathing abnormality in progressive neuromuscular disease.

Because the earliest abnormalities are subtle and stage-specific, the choice of polysomnographic thresholds carries enormous weight. Should the trigger for considering ventilation be a certain number of oxygen desaturations per hour, a defined percentage of sleep time spent below a saturation cutoff, an elevated transcutaneous or end-tidal carbon dioxide level, or some combination of these? Each option has methodological trade-offs. Desaturation indices borrowed from adult obstructive sleep apnea practice may miss the slow, sustained gas exchange deterioration typical of neuromuscular disease, where the abnormality is hypoventilation rather than discrete apneic events. Carbon dioxide measures, though more directly relevant to hypoventilation, are technically finicky in children, prone to signal drift and displacement, and not uniformly available across sleep laboratories.

These technical uncertainties form one strand of the letter’s argument. The authors raise methodological considerations about how criteria derived from a particular patient population and a particular set of recording practices can be generalized. Reference values for pediatric sleep studies differ by age, and children with neuromuscular disease span a wide developmental range, from toddlers with congenital myopathies to adolescents with advanced dystrophinopathies. A single threshold applied across that spectrum risks misclassifying both the youngest patients, whose normal physiology differs from school-age children, and those with slowly versus rapidly progressive conditions, whose trajectories of respiratory decline follow very different clocks.

The clinical considerations the authors emphasize are equally important. Polysomnography captures a single night, a snapshot that may not represent a child’s typical sleep, particularly in an unfamiliar laboratory environment where the first-night effect can suppress REM sleep and mask the very abnormalities clinicians are hunting for. A child whose REM time is curtailed on the study night may appear deceptively normal. Conversely, transient illness, nasal congestion, or anxiety can exaggerate abnormalities. Serial monitoring, careful correlation with daytime symptoms such as morning headaches, excessive sleepiness, poor school performance, and frequent nocturnal awakenings, and attention to trends over time may matter as much as any single numeric cutoff.

The stakes of getting these criteria right extend well beyond the sleep laboratory. Long-term non-invasive ventilation reshapes family life. Research on children with neuromuscular diseases who use ventilators, including work by Johannsen and colleagues cited in the letter, has examined the impact of long-term ventilator use on health-related quality of life and the mental health of affected children and their families, highlighting the need for a revised perspective on how these burdens are weighed. Initiating ventilation is not merely a technical prescription; it commits families to nightly routines, equipment maintenance, and an enduring reminder of disease progression. Criteria that are too permissive risk imposing these burdens without benefit, while criteria that are too restrictive risk depriving children of an intervention that, when appropriately timed, can improve sleep quality, daytime functioning, and potentially survival.

The letter also underscores a broader lesson about how evidence accumulates in pediatric sleep medicine. Large randomized trials are difficult to conduct in rare diseases, and much practice has been built on observational data and expert opinion. Studies that attempt to formalize criteria, such as the Dannenberg investigation, are valuable precisely because they make the reasoning explicit and testable. Letters such as that from Munir and colleagues serve as the peer community’s quality control, pressing authors on methodology, generalizability, and clinical applicability. This dialectic, proposal followed by critique followed by refinement, is how a field gradually converges on standards that clinicians can trust and families can understand.

For clinicians caring for children with neuromuscular disease, the practical message is one of calibrated vigilance. Sleep studies should be interpreted with awareness of REM physiology, age-appropriate norms, and the limitations of single-night testing, and the decision to start ventilation should integrate polysomnographic findings with symptoms, lung function trends, and family circumstances. For researchers, the exchange highlights the need for longitudinal studies that follow children from before ventilation is initiated, tracking which criteria best predict benefit, and for harmonization of carbon dioxide measurement and scoring practices across laboratories. The Islamabad authors’ contribution, though brief in the letter format, helps keep a consequential debate honest: the numbers on a sleep report are only as meaningful as the physiology, methodology, and human context behind them. As non-invasive ventilation becomes an ever more central therapy for children with weakened breathing muscles, refining the criteria that govern its initiation is not an academic exercise but a question with lifelong consequences for the children and families at its center.

Subject of Research: Polysomnographic criteria for initiating non-invasive ventilation in children with neuromuscular diseases

Article Title: Methodological and clinical considerations for polysomnographic criteria guiding non-invasive ventilation initiation in pediatric neuromuscular diseases

Article References: Munir, A. B., Imran, H., & Faraz, N. (2026). Methodological and clinical considerations for polysomnographic criteria guiding non-invasive ventilation initiation in pediatric neuromuscular diseases. Journal of Clinical Sleep Medicine, 22(1), Article 143. https://doi.org/10.1007/s44470-026-00166-9

Image Credits: AI Generated

DOI: 10.1007/s44470-026-00166-9

Keywords: polysomnography, non-invasive ventilation, pediatric neuromuscular disease, sleep-disordered breathing, REM-related hypoventilation, Duchenne muscular dystrophy, spinal muscular atrophy, nocturnal hypoventilation, carbon dioxide monitoring, sleep medicine, clinical criteria, ventilator initiation

The review, led by Nedra Whitehead of RTI International with colleagues from the US Centers for Disease Control and Prevention and several academic centers, combed through PubMed and EBSCO databases in a search last updated in March 2023. The team applied strict inclusion criteria: studies had to involve at least ten participants with one of the major muscular dystrophy subtypes, including Duchenne and Becker muscular dystrophy, congenital muscular dystrophy, facioscapulohumeral dystrophy, limb-girdle muscular dystrophy, or myotonic dystrophy. Only original research or prior systematic reviews published in English qualified. After screening, 95 studies made the cut, encompassing a total of 7,964 participants across seven studies of sleep evaluations, 94 studies of sleep disorders, and 13 studies of treatments.

The distribution of that literature is itself revealing. Myotonic dystrophy dominated the evidence base, with 61 studies, while Duchenne and Becker muscular dystrophy accounted for 20. Facioscapohumeral dystrophy drew nine studies, but congenital and limb-girdle muscular dystrophies were represented by a single study each, and three studies covered multiple dystrophy types. This uneven landscape means that clinicians treating rarer subtypes have had to extrapolate from conditions with very different mechanisms, a practice the new synthesis makes visible for the first time at this scale.

Perhaps the most striking finding concerns evaluation rates. Among people with Duchenne or Becker muscular dystrophy, only about half, 51 percent according to two studies covering 85 individuals, had ever undergone a sleep study. For myotonic dystrophy type 1, the figure was similarly incomplete: 65 percent across two studies of 327 individuals. These numbers matter because professional guidelines for both conditions explicitly recommend routine sleep assessment. In other words, even in the two dystrophies where the evidence and the recommendations are strongest, roughly half of affected individuals are navigating a disease known to compromise breathing during sleep without the objective testing that could detect it.

The reasons for the shortfall are likely multifactorial. Sleep-disordered breathing in neuromuscular disease often develops insidiously, and its symptoms, fragmented sleep, morning headaches, fatigue, can be mistaken for the general burden of living with a progressive muscle disorder. Diagnostic polysomnography requires overnight laboratory capacity, which is unevenly distributed, and patients with mobility limitations may face practical barriers to accessing sleep centers. The review’s authors assessed risk of bias by examining whether studies recruited participants in ways that selected for or against sleep symptoms, and they calculated weighted averages using only the lower-risk studies, a methodological discipline that strengthens confidence in the headline figures.

When it comes to the disorders themselves, the review documented a heavy burden. Excessive daytime sleepiness, measured by questionnaire, affected 39 percent of adults with myotonic dystrophy type 2 and 65 percent of adults with any myotonic dystrophy, compared with just 9 percent among controls. Other muscular dystrophy subtypes showed rates of 6 to 13 percent, meaning that pathological daytime sleepiness appears to be a distinctive signature of myotonic dystrophy rather than a generic consequence of muscle disease. That distinction has biological plausibility: myotonic dystrophy affects the central nervous system directly, and prior research has implicated altered hypocretin signaling, brain atrophy, and disrupted REM sleep architecture in the condition’s sleep pathology.

Sleep apnea, meanwhile, proved common across nearly the entire dystrophy spectrum. Reported frequencies ranged from 11 percent in a single limb-girdle dystrophy study to 65 percent in a single congenital muscular dystrophy study, with the review’s highlights noting a prevalence band of roughly 30 to 65 percent for congenital, Duchenne/Becker, facioscapulohumeral, and myotonic dystrophies. In Duchenne muscular dystrophy, the mechanism is relatively well understood: progressive weakness of the diaphragm and intercostal muscles impairs ventilation, particularly during REM sleep when breathing depends heavily on the diaphragm alone. Nocturnal hypoventilation, oxygen desaturation, and both obstructive and central apneic events follow. In congenital muscular dystrophy, central apnea has been documented for decades, suggesting involvement of brainstem respiratory control in addition to peripheral muscle weakness.

Treatment data painted a picture of underuse. Assisted ventilation, typically non-invasive positive pressure delivered through a mask at night, was reported by only 5 to 16 percent of individuals with myotonic dystrophy, despite the well-documented progression of respiratory insufficiency in that population. The range was wider for other conditions: five to 60 percent of people with myotonic dystrophy and 15 to 69 percent of those with facioscapulohumeral dystrophy used ventilation assistance in the included studies, figures that likely reflect differing disease stages and care settings rather than true population prevalence. For excessive daytime sleepiness, pharmacological options exist, with stimulants such as modafinil tested in randomized trials for myotonic dystrophy-related hypersomnia, yet only 8 percent of individuals with myotonic dystrophy in the review were taking medication for sleepiness.

The clinical stakes of closing these gaps are considerable. Untreated sleep-disordered breathing is associated with worsened quality of life, cognitive impairment, and cardiovascular strain, and in neuromuscular disease it can accelerate respiratory failure, the leading cause of death in several dystrophy subtypes. Non-invasive ventilation, when initiated appropriately, has transformed survival and daily functioning for people with Duchenne muscular dystrophy over recent decades. Identifying sleep apnea and hypoventilation early allows clinicians to time interventions, monitor cardiac arrhythmias that can interact with nocturnal desaturation, and address the daytime sleepiness and fatigue that erode school performance, employment, and independence. The review’s authors conclude that regular sleep evaluations may improve both the identification and treatment of sleep disorders and, by extension, the physical and mental health of people with muscular dystrophy.

What the review cannot yet answer is how to make routine sleep assessment a reality for every patient. The evidence base for congenital and limb-girdle dystrophies is thin enough that dedicated studies are clearly needed, and the heterogeneity of outcome definitions across the 95 included studies complicates precise comparison. Still, the synthesis delivers a clear message to neurologists, pulmonologists, primary care physicians, and families: sleep problems are not a side issue in muscular dystrophy but a central, measurable, and treatable dimension of the disease. With roughly half of the highest-risk patients never having undergone a sleep study, the simplest intervention, asking about sleep and referring for testing, may be among the most consequential steps a care team can take.

Subject of Research: The frequency of sleep evaluations, sleep disorders, and treatments among individuals with muscular dystrophy

Article Title: A systematic review of the frequency of sleep evaluations, sleep disorders, and treatments among individuals with muscular dystrophy

Article References: Whitehead, N., Alese, J. T., Hill, C., Enger, M., Zimmerman, J., Moore, A., Royer, J., Venkatash, S., Thomas, S., Do, B., & Jr Howard, J. F. (2026). A systematic review of the frequency of sleep evaluations, sleep disorders, and treatments among individuals with muscular dystrophy. Journal of Clinical Sleep Medicine, 22(1), Article 173. https://doi.org/10.1007/s44470-025-00041-z

Image Credits: AI Generated

DOI: 10.1007/s44470-025-00041-z

Keywords: muscular dystrophy, sleep disorders, sleep apnea, myotonic dystrophy, Duchenne muscular dystrophy, excessive daytime sleepiness, systematic review, non-invasive ventilation, polysomnography, sleep evaluation, hypersomnia, respiratory insufficiency

High-flow nasal cannula is a deceptively simple piece of technology. Instead of a mask covering the nose and mouth, heated, fully humidified gas is delivered through a wide-bore nasal interface at flow rates of up to 60 liters per minute, with the fraction of inspired oxygen adjusted to the patient’s needs. The therapy provides several physiological advantages: it generates low levels of positive airway pressure, flushes carbon dioxide out of the upper airway’s anatomical dead space, reduces the work of breathing, and improves clearance of secretions. Because it leaves the mouth free, patients can talk, eat, and drink while receiving support, and the open nasal interface dramatically reduces the claustrophobia and skin breakdown that plague mask users. Evidence in other neuromuscular diseases has hinted that patients tolerate it better than conventional ventilation, but data specific to ALS have been scarce, largely confined to small observational studies from high-income tertiary centers at moderate altitudes.

The new study, conducted by a multidisciplinary home respiratory care team, followed 18 ALS patients enrolled between January 2014 and December 2024 in a specialized home care program for neuromuscular disease. All had confirmed ALS, evidence of chronic respiratory failure, and clinician-documented intolerance to non-invasive ventilation attributable to interface problems, claustrophobia, excessive secretions, dysphagia, behavioral intolerance, or anatomical obstacles. The researchers combed electronic medical records for demographic details, comorbidities, arterial blood gas measurements, respiratory muscle strength, functional status, hospitalizations, infections, and mortality, comparing outcomes at the start of high-flow therapy with the last available follow-up.

The cohort tells its own story about how relentlessly ALS advances. The average age at which high-flow nasal cannula was initiated was 65.1 years, roughly eight years after the average age at diagnosis of 57.5. Women made up two-thirds of the group, and the mean body mass index was 23.6 kilograms per square meter. Notably, 61 percent of patients also carried a diagnosis of obstructive sleep apnea, a comorbidity that may compound ventilatory vulnerability. Comorbidities otherwise were sparse: four patients had hypertension, one had diabetes, and none had cancer, thrombotic disease, or autoimmune conditions beyond a single case of rheumatoid arthritis. These are, in other words, patients whose respiratory failure was driven by ALS itself rather than by a burden of other illness.

The pattern of intolerance to masks was revealing. In seven of the 18 cases, intolerance was partial, rooted in difficulty adapting to the interface, claustrophobic sensations, or discomfort with the delivered airflow. Six patients, about a third of the cohort, managed short periods of mask ventilation alternating with high-flow support, using the cannula for an average of about 4.7 hours daily. During the observation period, half of the patients required at least one hospitalization and a third experienced respiratory infections, rates the authors note are comparable to other ALS cohorts. Five patients, 27.8 percent, died during follow-up. The researchers are careful to frame these figures as reflections of advanced disease stage in a population that had already exhausted first-line support, rather than as failures of the high-flow strategy itself.

The physiological findings are the study’s technical core. Before starting therapy, patients showed a mean arterial pH of 7.40, a partial pressure of oxygen of 62.7 millimeters of mercury, a carbon dioxide partial pressure of 36.4 millimeters of mercury, and bicarbonate values ranging from 16 to 29 millimoles per liter. After a period on high-flow cannula, pH ticked up slightly to 7.42, oxygen pressure eased to 59.8 millimeters of mercury, carbon dioxide rose to 42.4 millimeters of mercury, and bicarbonate climbed to 27.8 millimoles per liter. None of these shifts reached statistical significance, and paired analyses confirmed wide confidence intervals spanning zero for every parameter. The authors interpret this stability as clinically meaningful: high-flow nasal cannula does not deliver enough inspiratory pressure support to raise tidal volume or reverse chronic hypercapnia the way mask ventilation can, yet in these carefully selected patients it maintained gas exchange without triggering respiratory acidosis or abrupt deterioration from carbon dioxide retention.

Functional trajectories told a starker story. The Barthel Index, a standard measure of independence in daily activities, fell by an average of 23.3 points, from 35.0 at the start of therapy to 11.7 at the final assessment, a highly significant decline driven chiefly by losses in walking and climbing stairs. The Cruz Roja Functional Classification showed the same slope: at baseline, nearly 78 percent of patients were already at Grades 3 or 4 of physical disability, and by final follow-up more than half had progressed to Grade 5, total dependence, while mild mental impairment rose from 22 percent to 39 percent of the group. Intriguingly, respiratory muscle strength did not follow suit. Maximum inspiratory and expiratory pressures remained essentially unchanged, with p-values of 0.97 and 0.76 respectively. This dissociation, the authors argue, underscores that functional decline in ALS is propelled not only by weakening respiratory muscles but by progressive limb weakness, bulbar dysfunction, and global neurological deterioration.

How do these results sit within the broader literature? The authors point to prior work in neuromuscular disease, including a study by Lionello and colleagues, that likewise documented high patient acceptance of high-flow therapy, with comfort, preserved speech and eating, and reduced claustrophobia cited as decisive advantages. One difference stands out: in that earlier study, three patients receiving continuous 24-hour high-flow support experienced treatment failure, whereas no complications directly attributable to the device were documented in the present cohort. The researchers caution that the descriptive design and small sample make this observation far from definitive, but they suggest it may reflect individualized titration of flow and oxygen and the close multidisciplinary follow-up that a dedicated home care program provides.

The study’s limitations are laid out candidly. A retrospective case series of 18 patients cannot establish causal relationships, and the absence of a comparison group prevents any direct judgment of whether high-flow cannula outperforms persisted mask use or invasive ventilation. Follow-up duration varied by patient because assessments relied on the last recorded clinical evaluation, and treatment discontinuation dates were not systematically documented. Baseline blood gases were drawn during routine care rather than a standardized protocol, so the researchers could not consistently determine whether they were obtained during mask ventilation, how much time elapsed before follow-up measurements, or how long patients had used masks before transitioning. These gaps limit the ability to characterize the longitudinal physiological effects of the therapy or to test whether prior mask exposure shaped tolerance.

Even with those caveats, the report matters for a population with few good options. It provides descriptive, real-world evidence that home-based high-flow nasal cannula is feasible in ALS patients who cannot tolerate masks, that it holds gas exchange steady despite limited ventilatory assistance, and that it may do so without device-attributable complications when embedded in structured multidisciplinary home care. The functional decline observed tracks the natural history of the disease rather than the support modality. The authors call for prospective comparative studies to define more precisely where high-flow therapy belongs in the respiratory management of ALS, but for patients facing the choice between an intolerable mask and an invasive tracheostomy, a comfortable nasal interface that buys stability may represent exactly the middle path the field has been looking for.

Subject of Research: Use of high-flow nasal cannula as home respiratory support in ALS patients intolerant to non-invasive ventilation

Article Title: Use of High‐Flow Nasal Cannula in Amyotrophic Lateral Sclerosis Patients Intolerant to Non‐Invasive Ventilation: A Case Series

Article References: Varon‐Vega, F., Franco Parra, C. E., Adame Ochoa, D. F., Uricoechea, N., Tuta‐Quintero, E., & Martinez Ayala, M. C. (2026). Use of High‐Flow Nasal Cannula in Amyotrophic Lateral Sclerosis Patients Intolerant to Non‐Invasive Ventilation: A Case Series. Respirology Case Reports, 14(9), Article e70744. https://doi.org/10.1002/rcr2.70744

Image Credits: AI Generated

DOI: 10.1002/rcr2.70744

Keywords: amyotrophic lateral sclerosis, high-flow nasal cannula, non-invasive ventilation, chronic respiratory failure, home respiratory care, arterial blood gases, ventilatory support, neuromuscular disease, Barthel Index, case series, respiratory muscle strength, bulbar dysfunction