Associations of Intraoperative Radial Arterial Systolic, Diastolic, Mean, and Pulse Pressures with Myocardial and Acute Kidney Injury after Noncardiac Surgery

Abstract

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Arterial pressure is a complex signal that can be characterized by systolic, mean, and diastolic components, along with pulse pressure (difference between systolic and diastolic pressures). The authors separately evaluated the strength of associations among intraoperative pressure components with myocardial and kidney injury after noncardiac surgery. Methods The authors included 23,140 noncardiac surgery patients at Cleveland Clinic who had blood pressure recorded at 1-min intervals from radial arterial catheters. The authors used univariable smoothing and multivariable logistic regression to estimate probabilities of each outcome as function of patients’ lowest pressure for a cumulative 5 min for each component, comparing discriminative ability using C-statistics. The authors further assessed the association between outcomes and both area and minutes under derived thresholds corresponding to the beginning of increased risk for the average patient. Results Out of 23,140 patients analyzed, myocardial injury occurred in 6.1% and acute kidney injury in 8.2%. Based on the lowest patient blood pressure experienced for greater than or equal to 5 min, estimated thresholds below which the odds of myocardial or kidney injury progressively increased (slope P < 0.001) were 90 mmHg for systolic, 65 mmHg for mean, 50 mmHg for diastolic, and 35 mmHg for pulse pressure. Weak discriminative ability was noted between the pressure components, with univariable C-statistics ranging from 0.55 to 0.59. Area under the curve in the highest (deepest) quartile of exposure below the respective thresholds had significantly higher odds of myocardial injury after noncardiac surgery and acute kidney injury compared to no exposure for systolic, mean, and pulse pressure (all P < 0.001), but not diastolic, after adjusting for confounding. Conclusions Systolic, mean, and pulse pressure hypotension were comparable in their strength of association with myocardial and renal injury. In contrast, the relationship with diastolic pressure was poor. Baseline factors were much more strongly associated with myocardial and renal injury than intraoperative blood pressure, but pressure differs in being modifiable.

Blood Pressure Components and Organ Injury: Reply

“…First, compared with previously published studies, this study had an important difference in the definition of myocardial injury after noncardiac surgery. 2 The outcome definition of myocardial injury in this study (i.e., elevation of troponin or creatinine kinase-myocardial bound during the first 7 postoperative days) 1 was different from that approved by the consensus diagnostic criteria in 2014, which defined myocardial injury after noncardiac surgery as "elevated post-operative troponin measurement judged as resulting from myocardial ischemia during or within 30 days after non-cardiac surgery." 3,4 In addition, this study did not exclude nonischemic etiologies (sepsis, arrythmias, pulmonary embolism, etc.).…”

“…A previous study showed that elevation of troponin levels in 11 to 14% cases after noncardiac surgery was due to nonischemic etiologies. 3 Therefore, without an adequate outcome assessor, the results of Ahuja et al 1 tend to overestimate the actual incidence of myocardial injury by including nonischemic etiologies. Although this exclusion was not possible because of the retrospective study design using electronic medical records, the authors should discuss this aspect in the study limitations.…”

“…5 As stated by the authors, the postoperative troponin concentration was measured in only 25% of the samples, and the authors assumed that myocardial injury was absent in patients without troponin surveillance. 1 This assumption can induce serious outcome detection bias. In clinical practice, postoperative cardiac biomarkers (troponin or creatinine kinase-myocardial bound) are not measured routinely.…”

“…D r. Yonekura notes that we failed to exclude patients with potential nonischemic causes of troponin elevation, thus possibly including some patients who did not actually have myocardial injury after noncardiac surgery. 1 It is likely that most patients who have troponin elevations and conditions that might falsely elevate troponin concentrations actually do have myocardial injury. Nonetheless, nonischemic causes should have been excluded from our analyses.…”

Prediction of hypotension events with physiologic vital sign signatures in the intensive care unit

“…Hypotension is known to be the most consistent manifestation of decompensated shock leading to major organ failure and death [1]. Hypotension, along with other chronic risk factors, is associated with an increased chance of acute kidney injury, myocardial ischemia, and mortality [2,3]. However, the underlying signatures from hemodynamic monitoring variables that portend impending hypotension are not clearly identified [4].…”