Hip surgery is one of the most common and consequential operations performed in older adults, offering mobility and independence to patients with fractures, arthritis, and other disabling conditions. Yet the procedure also exposes patients to a dangerous postoperative complication: venous thromboembolism, or VTE. This term includes deep-vein thrombosis, in which a clot develops most often in the leg, and pulmonary embolism, in which a clot travels to the lungs. New research is examining whether an event that occurs during the operation itself—intraoperative hypotension—could help identify elderly patients at heightened risk of developing VTE after surgery.

Intraoperative hypotension refers to an abnormal fall in blood pressure while a patient is under anesthesia. It may be defined using an absolute threshold, such as a mean arterial pressure below a specific value, or by considering how far blood pressure drops from the patient’s normal baseline. Mean arterial pressure is particularly important because it reflects the pressure driving blood through vital organs. During hip surgery, blood pressure can fall because of anesthesia-induced widening of blood vessels, blood loss, reduced cardiac output, dehydration, or the physiological stress associated with trauma and inflammation.

The possible connection between low blood pressure during surgery and postoperative thrombosis is biologically complex. At first glance, hypotension and clotting appear to represent opposite problems: one involves insufficient circulation, while the other involves excessive coagulation. In reality, both may arise from a shared physiological disturbance. Reduced blood flow can promote venous stasis, one of the three major elements of Virchow’s triad, which also includes damage to the vessel wall and increased blood coagulability. Prolonged immobility before and after surgery, tissue injury, inflammatory signaling, and activation of platelets and clotting proteins can further intensify this risk.

Hip surgery is an especially important setting in which to study this relationship. Older patients often arrive at the hospital after a fall or fracture, having already experienced reduced mobility, dehydration, pain, and systemic stress. The operation itself can injure tissue and release inflammatory mediators, while postoperative recovery may require several days of limited movement. Age-related changes in the vascular system, a higher prevalence of cancer, heart disease, obesity, and previous thrombosis may add further layers of vulnerability. Together, these factors create a clinical environment in which even modest differences in perioperative circulation could become meaningful.

The research focuses on whether intraoperative blood-pressure patterns can improve the prediction of postoperative VTE beyond conventional risk factors. Rather than treating hypotension as a simple yes-or-no event, investigators may analyze its duration, depth, cumulative exposure, and timing. A brief decline in mean arterial pressure may carry a different implication from a prolonged or repeated episode. The relationship may also depend on whether hypotension occurs during anesthesia induction, the surgical procedure, or the early recovery period, when patients may still be hemodynamically unstable.

To translate these observations into clinical practice, the investigators are constructing a risk prediction model for elderly patients undergoing hip surgery. Such a model could combine intraoperative blood-pressure measurements with demographic, clinical, laboratory, and surgical information. Potential predictors include age, sex, fracture type, preoperative mobility, previous VTE, cancer, cardiovascular disease, renal function, hemoglobin concentration, operative duration, estimated blood loss, transfusion, type of anesthesia, and the timing of postoperative mobilization. The model may also incorporate the use and timing of pharmacological thromboprophylaxis, which commonly includes anticoagulant medications administered after surgery.

A useful prediction model must do more than identify statistical associations. It must be calibrated, meaning that its estimated probabilities should correspond reasonably well with the actual frequency of VTE. It must also discriminate between patients at higher and lower risk, often assessed through measures such as the area under the receiver operating characteristic curve. Internal validation can test whether the model performs consistently within the original dataset, while external validation in a separate hospital or patient population is necessary to determine whether it can generalize beyond the conditions in which it was developed. Without such validation, a model may simply memorize patterns specific to one group of patients.

If the association between intraoperative hypotension and postoperative VTE is confirmed, the findings could influence perioperative monitoring and prevention strategies. Blood pressure management is already central to protecting the brain, heart, and kidneys, but a thrombosis-related signal could broaden the clinical importance of avoiding prolonged hypotension. Patients identified as high risk might receive more intensive surveillance for leg swelling, unexplained tachycardia, chest pain, or oxygen decline. Clinicians could also consider earlier mobilization, closer review of anticoagulant timing, and individualized decisions about the balance between preventing clots and avoiding bleeding.

The study does not necessarily mean that intraoperative hypotension directly causes VTE, and this distinction is critical. Low blood pressure may instead act as a marker of more severe illness, greater blood loss, longer surgery, or a stronger inflammatory response. Older patients with complicated operations may be more likely to experience both hypotension and thrombosis for related but separate reasons. The model’s value will therefore depend on careful adjustment for confounding factors, transparent reporting of missing data, and evaluation across different surgical techniques, anesthesia practices, and thromboprophylaxis protocols. Even with those safeguards, prediction is not the same as prevention. The significance of the work lies in bringing an overlooked intraoperative signal into a broader effort to recognize, stratify, and reduce one of the most serious complications facing older adults after hip surgery.

Subject of Research: The relationship between intraoperative hypotension and postoperative venous thromboembolism in elderly patients undergoing hip surgery, including the development of a risk prediction model.

Article Title: Relationship between intraoperative hypotension and postoperative venous thromboembolism in elderly patients undergoing hip surgery and construction of a risk prediction model

Image Credits: AI Generated

Keywords: Intraoperative hypotension, venous thromboembolism, deep-vein thrombosis, pulmonary embolism, hip surgery, elderly patients, perioperative medicine, risk prediction model, thromboprophylaxis, anesthesia, postoperative complications

During noncardiac surgeries, maintaining stable hemodynamics is crucial for minimizing the risks of postoperative complications. However, intraoperative hypotension, defined as a transient drop in blood pressure during surgery, can be frequently observed due to various anesthetic and physiological factors. The study led by Liu and colleagues offers a thorough retrospective analysis of how these drops in blood pressure correlate with the incidence of AKI, highlighting a rising concern in surgical practices.

Elderly patients, especially those categorized as super elderly, face unique health challenges. Their kidneys often have reduced functional reserve and renal blood flow can be compromised due to aging. Recognizing this, the researchers focused on a cohort of patients aged 65 and above undergoing elective noncardiac surgeries. This demographic was selected to better understand how age exacerbates the risks associated with intraoperative hypotension and the subsequent likelihood of developing AKI.

The study utilized a comprehensive dataset to analyze outcomes, focusing on those who experienced episodes of intraoperative hypotension. Measurements included systolic blood pressure drops that persisted for five minutes or more during any point of the procedure. This criterion was vital, as it allowed the study to define a clear threshold for hypotension directly correlated with surgical outcomes.

To quantify the risk of AKI, the researchers employed established criteria, including changes in serum creatinine levels and urine output reductions within 48 hours post-surgery. AKI was assessed as a categorical variable, allowing the researchers to gauge its prevalence within the patient cohort effectively. The results of such findings are critical, as they elucidate the intricate relationship between intraoperative management and postoperative renal health.

The implications of these findings are profound. Elevated rates of acute kidney injury post-surgery can lead to longer hospital stays, increased medical costs, and higher mortality rates. Liu et al.’s research emphasizes that intraoperative hypotension is not merely a transient issue but may have lasting ramifications on a patient’s renal function, particularly in an aging population where every aspect of health is crucial.

One particularly striking aspect of the study is how it aligns with existing literature regarding blood pressure management in surgical settings. Multiple studies have previously documented the detrimental effects of hypotension on various organs, yet Liu et al. expand the dialogue by specifically targeting a geriatric cohort, thus filling a critical gap in surgical research. Their findings underscore the need for anesthesiologists and surgical teams to be vigilant regarding blood pressure management throughout procedures.

Additionally, the research opens doors to potential interventions that could modify how intraoperative hypotension is managed. Recommendations from the study may include proactive monitoring strategies and preemptive measures to maintain hemodynamic stability. Such practices not only hold promise for reducing the incidence of postoperative complications but also suggest a broader rethink regarding perioperative care protocols for elderly patients.

Surgeons and anesthesiologists can take valuable lessons from these findings, especially as the aging population continues to grow. The study advocates for improved awareness and education among healthcare professionals regarding the specific risks faced by older patients. Enhanced training in recognizing and responding to episodes of intraoperative hypotension may be necessary to mitigate the risk of AKI.

Further research is warranted, as Liu et al. point out, to establish guidelines that are reflective of the complexities involved in treating elderly populations. Future studies could also explore the potential for specific pharmacological interventions tailored to preventing hypotension and protecting kidney function in high-risk surgical patients.

In conclusion, the clear link between intraoperative hypotension and AKI in elderly patients not only adds significant knowledge to surgical practices but also raises awareness about the need for targeted approaches within this vulnerable population. Liu et al.’s research offers crucial insights that could influence clinical guidelines and improve health outcomes for elderly patients undergoing noncardiac surgeries.

As this study highlights, the moves towards enhanced geriatric surgical care are essential. Capturing the needs of this demographic will require systemic changes in how surgeries are approached, ensuring that interventions are informed by research such as this one. Intraoperative blood pressure management may become not only a routine monitoring goal but also a critical measure of safeguarding against the cascading effects of surgical complications.

With this emerging body of evidence, it is evident that the surgical community must prioritize the development of strategies that address intraoperative hypotension, particularly in patients who are at increased risk for adverse effects. By doing so, healthcare practitioners can aim not only for surgical success but also for the overarching goal of preserving patient quality of life.

In summary, the findings of Liu et al. serve as a vital call to action within surgical disciplines. As we continue to unravel the complexities of intraoperative care, understanding the interplay between hypotension and kidney health will pave the way for innovative practices and improved patient outcomes, thereby enhancing surgical care for the world’s elderly population.

Subject of Research: The relationship between intraoperative hypotension and acute kidney injury in elderly patients undergoing noncardiac surgery.

Article Title: The relationship between intraoperative hypotension and acute kidney injury in elderly and super elderly patients undergoing noncardiac surgery: a retrospective cohort analysis.

Article References:

Liu, R., Chen, J., Peng, Y. et al. The relationship between intraoperative hypotension and acute kidney injury in elderly and super elderly patients undergoing noncardiac surgery: a retrospective cohort analysis.
BMC Geriatr (2025). https://doi.org/10.1186/s12877-025-06944-z

Image Credits: AI Generated

DOI: 10.1186/s12877-025-06944-z

Keywords: intraoperative hypotension, acute kidney injury, elderly patients, noncardiac surgery, surgical complications, hemodynamic management, renal function, retrospective cohort analysis.