Implications for perioperative practice of changes in guidelines on the management of hypertension: challenges and opportunities

Risk Factors and Clinical Outcomes of Perioperative Hypotension in the Neck of Femur Fracture Surgery: A Case-Control and Cohort Analysis

Introduction Neck-of-femur (NOF) fractures have high prevalence rates and require prompt surgical intervention for better outcomes. Perioperative hypotension (POH) in the geriatric population has poor outcomes with several contributing factors. The study intends to explore these risk factors and their correlation with patient outcomes.  Methodology We studied a total of 276 patients who underwent surgical fixation of the NOF fracture at St Peter's Hospital, Surrey, from June 1, 2022, to June 1, 2023. Patients with POH were identified; the risk factors and one-year outcome were studied to obtain the results. We used odds ratio (OR), relative risk (RR), and multivariate regression to analyse the statistical association within the data. Results The incidence of POH was 68% (188/276) which included preoperative hypotension (9.78%), intraoperative hypotension (48.55%), and postoperative hypotension with a mean arterial pressure (MAP) of <65 mmHg (24.63%) and fall of systolic blood pressure to less than 80% (34.42%). Statistically significant risk factors were hypertension (OR: 1.330), heart disease (OR: 2.768), and hemoglobin (Hg) drop (OR: 1.42). The outcomes we studied were all statistically significant, with an RR of more than one. It includes postoperative delirium (RR: 2.037), postoperative 30-day morbidity (RR: 4.008), postoperative 30-day mortality (RR: 6.12), 365-day mortality (RR: 2.224), postoperative delay in mobilisation (RR: 1.329), and prolonged length of stay (RR: 1.273).  Conclusion The study shows a clear association between POH and increased postoperative complications, highlighting the need for prompt intervention. This case-control study identified hypertension, history of heart disease, and perioperative blood loss as significant risk factors for developing POH. Also, this study demonstrates that POH is significantly associated with adverse outcomes, including the increased risk of delirium, prolonged hospital stays, and elevated 30-day morbidity in elderly patients undergoing hip fracture surgery. The findings also indicated that the duration of hypotension did not directly influence the outcomes; its occurrence alone is a significant factor in developing these complications.

Preoperative Renin-Angiotensin System Antagonists Intake and Blood Pressure Responses During Ambulatory Surgical Procedures: A Prospective Cohort Study

BACKGROUND

There is limited evidence to inform the association between the intake of angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin II receptor blockers (ARBs) and intraoperative blood pressure (BP) changes in an ambulatory surgery population.

METHODS

Adult patients who underwent ambulatory surgery and were discharged on the same day or within 24 hours of their procedure were enrolled in this prospective cohort study. The primary outcome of the study was early intraoperative hypotension (first 15 minutes of induction). Secondary outcomes included any hypotension, BP variability, and recovery. Hypotension was defined as a decrease in systolic BP of >30% from baseline for ≥5 minutes or a mean BP of <55 mm Hg. Four exposure groups were compared (no antihypertensives, ACEI/ARB intake <10 hours before surgery, ACEI/ARB intake ≥10 hours before surgery, and other antihypertensives).

RESULTS

Of the 537 participants, early hypotension was observed in 25% (n = 134), and any hypotension in 41.5% (n = 223). Early hypotension occurred in 30% (29 of 98) and 41% (17 of 41) with the intake of ACEI/ARBs <10 and ≥10 hours before surgery, respectively, compared to 30% (9 of 30) with other antihypertensives and 21% (79 of 368) with no antihypertensives ( P = .02). Those on antihypertensives also experienced any hypotension more frequently than those who were not on antihypertensives ( P < .001). After adjusting for age and baseline BP in a regression analysis, antihypertensive exposure groups were observed to be associated only with any intraoperative hypotension ( P = .012). In the ACEI/ARB subset, there was no evidence of an association between time since the last ACEI/ARB dose, and hypotension or minimum mean or systolic BP. Compared to normal baseline BP, BP ≥ 140/90 mm Hg increased the odds of early and any hypotension (odds ratio [OR], 3.9; 95% confidence interval [CI], 2.1-7.1 and OR, 7.7; 95% CI, 3.7-14.9, respectively; P < .001). Intraoperative variability in systolic and diastolic BP demonstrated significant differences with age, baseline BP, and antihypertensive exposure group ( P < .001).

CONCLUSIONS

Early and any hypotension occurred more frequently in those on antihypertensives than those not on antihypertensives. Unadjusted associations between antihypertensive exposure and intraoperative hypotension were largely explained by baseline hypertension rather than the timing of ACEI/ARBs or type of antihypertensive exposure. Patients with hypertension and on treatment experience more intraoperative BP variability and should be monitored appropriately.

Heterogeneous impact of hypotension on organ perfusion and outcomes: a narrative review

Arterial blood pressure is the driving force for organ perfusion. Although hypotension is common in acute care, there is a lack of accepted criteria for its definition. Most practitioners regard hypotension as undesirable even in situations that pose no immediate threat to life, but hypotension does not always lead to unfavourable outcomes based on experience and evidence. Thus efforts are needed to better understand the causes, consequences, and treatments of hypotension. This narrative review focuses on the heterogeneous underlying pathophysiological bases of hypotension and their impact on organ perfusion and patient outcomes. We propose the iso-pressure curve with hypotension and hypertension zones as a way to visualize changes in blood pressure. We also propose a haemodynamic pyramid and a pressure-output-resistance triangle to facilitate understanding of why hypotension can have different pathophysiological mechanisms and end-organ effects. We emphasise that hypotension does not always lead to organ hypoperfusion; to the contrary, hypotension may preserve or even increase organ perfusion depending on the relative changes in perfusion pressure and regional vascular resistance and the status of blood pressure autoregulation. Evidence from RCTs does not support the notion that a higher arterial blood pressure target always leads to improved outcomes. Management of blood pressure is not about maintaining a prespecified value, but rather involves ensuring organ perfusion without undue stress on the cardiovascular system.