Background: Major determinants of blood pressure (BP) include sex and age. In youth, females have lower BP than males, yet in advanced age, more pronounced BP increases result in higher average BPs in females over 65. This hypothesis-generating study explored whether age-related BP divergence impacts the incidence of sex-specific intraoperative hypotension (IOH) or hypertension. Methods: We systematically searched PubMed and Embase databases for studies reporting intraoperative BP in males and females in non-cardiac surgery. We analyzed between-sex differences in the incidence of IOH and intraoperative hypertension (primary endpoint). Results: Among 793 identified studies, 14 were included in this meta-analysis, comprising 1,110,636 patients (56% female). While sex was not associated with IOH overall (females: OR 1.10, 95%CI [0.98–1.23], I² = 99%), a subset of studies with an average age ≥65 years showed increased exposure to IOH in females (OR 1.17, 95%CI [1.01–1.35], I² = 94%). One study reported sex-specific differences in intraoperative hypertension, with a higher incidence in females (31% vs. 28%). Conclusions: While sex-specific reporting on intraoperative BP was limited, IOH did not differ between sexes. However, an exploratory subgroup analysis offers the hypothesis that females of advanced age may face an increased risk of IOH, warranting further investigation.

Background: Hypotension is common in the post-anesthesia care unit (PACU) and intensive care unit (ICU), and is associated with adverse patient outcomes. The Hypotension Prediction Index (HPI) algorithm has been shown to accurately predict hypotension in mechanically ventilated patients in the OR and ICU and to reduce intraoperative hypotension (IOH). Since positive pressure ventilation significantly affects patient hemodynamics, we performed this validation study to examine the performance of the HPI algorithm in a non-ventilated PACU and ICU population. Materials & Methods: The performance of the HPI algorithm was assessed using prospectively collected blood pressure (BP) and HPI data from a PACU and a mixed ICU population. Recordings with sufficient time (≥3 h) spent without mechanical ventilation were selected using data from the electronic medical record. All HPI values were evaluated for sensitivity, specificity, predictive value, and time-to-event, and a receiver operating characteristic (ROC) curve was constructed. Results: BP and HPI data from 282 patients were eligible for analysis, of which 242 (86%) were ICU patients. The mean age (standard deviation) was 63 (13.5) years, and 186 (66%) of the patients were male. Overall, the HPI predicted hypotension accurately, with an area under the ROC curve of 0.94. The most used HPI threshold cutoff in research and clinical use, 85, showed a sensitivity of 1.00, specificity of 0.79, median time-to-event of 160 s [60–380], PPV of 0.85, and NPV of 1.00. Conclusion: The absence of positive pressure ventilation and the influence thereof on patient hemodynamics does not negatively affect the performance of the HPI algorithm in predicting hypotension in the PACU and ICU. Future research should evaluate the feasibility and influence on hypotension and outcomes following HPI implementation in non-ventilated patients at risk of hypotension.

Many physiological processes show a diurnal rhythm, including sympathetic and parasympathetic tone, adrenal hormone secretion and blood pressure. Since these physiological rhythms may affect the sensitivity to anaesthesia, we hypothesised that the time of day when anaesthesia induction occurs may affect the incidence of post-induction hypotension. This was a post-hoc propensity score matched analysis of prospectively collected blood pressure data of 760 elective non-cardiac surgery patients receiving general anaesthesia. The primary endpoint was the incidence of post-induction hypotension, defined as mean arterial pressure < 65 mmHg for at least one minute. Secondary endpoints were a > 30 % decrease in mean arterial pressure, and baroreflex sensitivity. In the analysis of 237 propensity score matched pairs, post-induction hypotension was more frequent if anaesthesia induction occurred in the morning (08:00 AM - 12:00 PM) (odds ratio (OR) 1.48, 95 % confidence interval (CI): 1.00-2.20, p = 0.049). Secondary analyses of the matched cohort showed that a > 30 % decrease in mean arterial pressure was likewise more frequent in the morning than the afternoon (12:00 PM - 17:00 PM) (OR 1.45, 95 % CI: 1.00-2.11, p = 0.0499), but no differences in instantaneous baroreflex sensitivity were observed. Post-induction hypotension was more frequent in the morning compared to the afternoon. While this finding is in line with the presumed physiological mechanisms, it may be affected by unmeasured confounding. These findings should be replicated in larger, preferably randomised, studies to confirm whether a causal relationship between the time of day of anaesthesia induction and post-induction hypotension exists. Clinical registration number This study was registered in the Dutch Medical Research in Humans (OMON) register on 18 June 2019 (ID: NL7810). The study was approved by the Medical Ethics Committee of the Amsterdam UMC, location AMC, Netherlands in December 2018 (NL 6748.018.18; 2018).