Postoperative Hypotension After Noncardiac Surgery and the Association With Myocardial Injury

Victor G. B. Liem, M.D., M.Sc.; Sanne E. Hoeks, Ph.D.; Kristin H. J. M. Mol, M.D., M.Sc.; Jan Willem Potters, M.D., Ph.D.; Frank Grüne, M.D., Ph.D.; Robert Jan Stolker, M.D., Ph.D.; Felix van Lier, M.D., Ph.D.

Disclosures

Anesthesiology. 2020;133(3):510-522. 

In This Article

Abstract and Introduction

Abstract

Background: Intraoperative hypotension has been associated with postoperative morbidity and early mortality. Postoperative hypotension, however, has been less studied. This study examines postoperative hypotension, hypothesizing that both the degree of hypotension severity and longer durations would be associated with myocardial injury.

Methods: This single-center observational cohort was comprised of 1,710 patients aged 60 yr or more undergoing intermediate- to high-risk noncardiac surgery. Frequent sampling of hemodynamic monitoring on a postoperative high-dependency ward during the first 24 h after surgery was recorded. Multiple mean arterial pressure (MAP) absolute thresholds (50 to 75 mmHg) were used to define hypotension characterized by cumulative minutes, duration, area, and time-weighted-average under MAP. Zero time spent under a threshold was used as the reference group. The primary outcome was myocardial injury (a peak high-sensitive troponin T measurement 50 ng/l or greater) during the first 3 postoperative days.

Results: Postoperative hypotension was common, e.g., 2 cumulative hours below a threshold of 60 mmHg occurred in 144 (8%) patients while 4 h less than 75 mmHg occurred in 824 (48%) patients. Patients with myocardial injury had higher prolonged exposures for all characterizations. After adjusting for confounders, postoperative duration below a threshold of 75 mmHg for more than 635 min was associated with myocardial injury (adjusted odds ratio, 2.68; 95% CI, 1.46 to 5.07, P = 0.002). Comparing multiple thresholds, cumulative durations of 2 to 4 h below a MAP threshold of 60 mmHg (adjusted odds ratio, 3.26; 95% CI, 1.57 to 6.48, P = 0.001) and durations of more than 4 h less than 65 mmHg (adjusted odds ratio, 2.98; 95% CI, 1.78 to 4.98, P < 0.001) and 70 mmHg (adjusted odds ratio, 2.18; 95% CI, 1.37 to 3.51, P < 0.001) were also associated with myocardial injury. Associations remained significant after adjusting for intraoperative hypotension, which independently was not associated with myocardial injury.

Conclusions: In this study, postoperative hypotension was common and was independently associated with myocardial injury.

Introduction

Myocardial injury after surgery is common and remains a severe postoperative complication associated with a poor prognosis.[1,2] In the perioperative setting, myocardial injury is usually clinically silent and often unnoticed, yet has identical increased risk in mortality as detected myocardial ischemia.[3] As a potential modifiable factor,[4] intraoperative hypotension has been increasingly investigated and has been suggested as a major contributor to postoperative myocardial injury,[5–7] possibly due to an oxygen supply-demand mismatch from end-organ perfusion disruption. Moreover, intraoperative hypotension has additionally been associated with postoperative acute kidney injury,[5,8] stroke,[9] and mortality.[10,11]

Most studies investigating the effects of intraoperative hypotension and adverse postoperative outcome did not include or account for hypotension during the (early) postoperative period. During surgery, patients are under continuous hemodynamic supervision with adequate blood pressure management opportunities to intervene. On the ward, patients are monitored in 4-to-6-h intervals, where hypotension may be unnoticed, can persist for prolonged episodes, and may potentially be more harmful during this critical phase. Recent studies have confirmed postoperative hypotension to be associated with myocardial injury[12,13] and infarction.[14] Although defining hypotension in the perioperative setting remains challenging with over 140 different definitions[15] and no international consensus to date, postoperative organ injury seems to be a function of both hypotension severity and duration.[16,17] However, papers report limited blood pressure characterizations due to infrequent postoperative blood pressure monitoring and/or a poorly defined measure of postoperative hypotension. Consequently, the current consensus on postoperative hypotension cannot accurately state at which postoperative thresholds harm may occur.[17] It is therefore imperative to explore this potentially modifiable factor in further detail.

The primary aim of this study was to determine whether postoperative hypotension in the first 24 h after noncardiac surgery was associated with myocardial injury. Multiple mean arterial pressure (MAP) thresholds were used to define postoperative hypotension, and different characterizations were investigated. We hypothesized that both the degree of postoperative hypotension severity and longer durations would be associated with myocardial injury.

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