Reported definitions of intraoperative hypotension in adults undergoing non-cardiac surgery under general anaesthesia: a review

Abstract

Background Intraoperative hypotension (IOH) during non-cardiac surgery is common and associated with major adverse kidney, neurological and cardiac events and even death. Given that IOH is a modifiable risk factor for the mitigation of postoperative complications, it is imperative to generate a precise definition for IOH to facilitate strategies for avoiding or treating its occurrence. Moreover, a universal and consensus definition of IOH may also facilitate the application of novel and emerging therapeutic interventions in treating IOH. We conducted a review to systematically record the reported definitions of intraoperative hypotension in adults undergoing non-cardiac surgery under general anaesthesia. Methods In accordance with Cochrane guidelines, we searched three online databases (OVID [Medline], Embase and Cochrane Library) for all studies published from 1 January 2000 to 6 September 2020. We evaluated the number of studies that reported the absolute or relative threshold values for defining blood pressure. Secondary aims included evaluation of the threshold values for defining IOH, the methodology for accounting for the severity of hypotension, whether the type of surgical procedure influenced the definition of IOH, and whether a study whose definition of IOH aligned with the Perioperative Quality Initiative-3 workgroup (POQI) consensus statement for defining was more likely to be associated with determining an adverse postoperative outcome. Results A total of 318 studies were included in the final qualitative synthesis. Most studies (n = 249; 78.3%) used an absolute threshold to define hypotension; 150 (60.5%) reported SBP, 117 (47.2%) reported MAP, and 12 (4.8%) reported diastolic blood pressure (DBP). 126 (39.6%) used a relative threshold to define hypotension. Of the included studies, 153 (48.1%) did not include any duration variable in their definition of hypotension. Among the selected 318 studies 148 (46.5%) studies defined IOH according to the POQI statement. When studies used a “relative blood pressure change” to define IOH, there was a weaker association in detecting adverse postoperative outcomes compared to studies who reported “absolute blood pressure change” (χ2(2) = 10.508, P = 0.005, Cramér’s V = 0.182). When studies used the POQI statement definition of hypotension or defined IOH by values higher than the POQI statement definition there were statistical differences observed between IOH and adverse postoperative outcomes (χ2(1) = 6.581, P = 0.037, Cramér’s V = 0.144). When both the duration of IOH or the numbers of hypotensive epochs were evaluated, we observed a significantly stronger relationship between the definition of IOH use the development of adverse postoperative outcomes. (χ2(1) = 4.860, P = 0.027, Cramér’s V = 0.124). Conclusions Most studies defined IOH by absolute or relative changes from baseline values. There are substantial inconsistencies in how IOH was reported. Further, definitions differed across different surgical specialities. Our findings further suggest that IOH should be defined using the absolute values stated in the POQI statement i.e., MAP < 60–70 mmHg or SBP < 100 mmHg. Finally, the number of hypotensive epochs or time-weighted duration of IOH should also be reported.

Provisional Decision-Making for Perioperative Blood Pressure Management: A Narrative Review

“…Bijker et al [ 49 ] identified 140 definitions of IOH after a review of 130 articles. The most used definition of IOH was as follows: a decrease in the systolic BP of more than 20% from the baseline BP or a MAP < 65 mmHg [ 50 , 51 ]. The latter, also known as absolute thresholds, is used more frequently for the following reasons: (1) baseline BP measurements are often unknown, and approximately one-third of patients do not have a baseline BP value preoperatively, as described by Monk et al [ 28 ]; (2) relative thresholds are not superior to absolute thresholds in predicting unfavorable outcomes as reported by Salmasi et al [ 52 ] in a large-sample retrospective cohort analysis; (3) absolute thresholds are concrete and easier to use in decision-making; and (4) preoperative BP measurements are often elevated due to tension and anxiety.…”

“…Several studies [ 16 , 28 , 52 – 76 ] found that IOH was associated with postoperative detrimental outcomes (such as AKI, myocardial injury, and neurocognitive disorders), which is related to the duration and magnitude of hypotension [ 77 ], suggesting that IOH should be avoided perioperatively ( Table 1 ). Based on existing evidence [ 51 , 56 , 58 , 74 , 75 ], intraoperative MAP should be maintained above 65 mmHg in normal adult patients, and in patients with other comorbidities (for example, coronary artery disease and carotid stenosis), the intraoperative MAP must be individualized based on the patient's pathophysiology and clinical situation. For example, the MAP of patients with chronic hypertension should be maintained above 70 mmHg.…”

Ultrasound-guided anterior iliopsoas muscle space block effectively reduces intraoperative hypotension in elderly adults undergoing hip surgery: A randomised controlled trial

“…Evidence has demonstrated that longer periods of SBP < 100 mmHg following non-cardiac surgery are related with an increased risk of organ damage and death ( Sessler et al, 2019 ). Based on Weinberg et al (2022) , 153 studies (48.1%) did not include any duration variable in the definition of hypotension; however, IOH should be defined using the absolute values indicated in the POQI statement ( Sessler et al, 2019 ); that is, MAP < 60–70 mmHg or SBP < 100 mmHg. Accordingly, we defined IOH as SBP < 100 mmHg in the current study.…”

“…The definition of IOH remains controversial ( Filiberto et al, 2021 ). Based on the Perioperative Quality Initiative (POQI) statement ( Sessler et al, 2019 ) and related studies, we defined IOH as a SBP < 100 mmHg ( Weinberg et al, 2022 ). As primary endpoints, a composite measure of IOH incidence, including frequency, absolute duration, and relative duration (percentage of total anaesthesia time), was established for this investigation, as stated by Schneck et al (2020) , while secondary endpoints included the pain score recorded 60 min after surgery and perioperative sufentanil dose.…”

Incidence of Intraoperative Hypotension during Non-cardiac Surgery in Community Anesthesia Practice: A retrospective observational analysis

“…IOH has been reported in 5-99% of surgical cases. 3,24,25 Limiting to studies that use a similar MAP threshold of 65 mmHg, the incidence of IOH ranges from 19-88% for MAP < 65 mmHg for at least 1 minute, 3,8,26 45-49% for at least 5 minutes, 3,26 and 31% for at least 10 minutes. 3,26 Most previous studies are from major academic institutions.…”