Abstract
BackgroundPatients undergo cardiac preoperative evaluation to identify those at risk of adverse perioperative cardiac events. The Revised Cardiac Risk index is commonly used for this task, although it is unable to accurately risk stratify in all patients. This may be partly a result of intraoperative events which significantly modify preoperative risk.MethodsWe conducted a systematic review to identify independent intraoperative predictors of adverse cardiac events in patients undergoing non-cardiac surgery. Four databases (Ovid Healthstar 1966 to Jan 2012, Ovid Medline 1946 to 6 March 2012, EMBASE 1974 to March 05 2012 and The Cochrane Library to March 06 2012) were searched.ResultsFourteen eligible studies were identified. The need for intraoperative blood transfusion (odds ratio (OR), 2.3; 95% confidence interval (CI), 1.4-3.3), vascular surgery (OR, 2.3; 95% CI, 1.2-3.4) and emergent/urgent surgery (OR, 2.3; 95% CI, 1.1-3.5) were the only independent intraoperative risk predictors identified in more than study. Other independent intraoperative factors identified included a >20 mmHg fall in mean arterial blood pressure for > 60 min (OR, 3.0; 95% CI, 1.8-4.9), >30% increase in baseline systolic pressure (OR, 8.0; 95% CI, 1.3-50), tachycardia in the recovery room (>30 beats per min (bpm) from baseline for >5 min) (OR, 7; 95% CI, 1.9-26), new onset atrial fibrillation (OR, 6.6; 95% CI, 2.5-20), hypothermia (OR, 2.2; 95% CI, 1.1-5) and remote ischemic preconditioning (OR, 0.22; 95% CI, 0.07-0.67). Other markers of surgical complexity were not independently associated with postoperative adverse cardiac outcomes. None of these studies controlled for blood transfusion.ConclusionsIntraoperative events significantly increase the risk for postoperative cardiac complications, although only intraoperative blood transfusion has strong evidence supporting this finding. It is possible that modification of these intraoperative risk factors by anesthetists and surgeons may reduce postoperative cardiac events and improve outcome. The Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) Study will add important information to understanding intraoperative risk factors for adverse cardiac events.
Highlights
Patients undergo cardiac preoperative evaluation to identify those at risk of adverse perioperative cardiac events
Most of these factors play a dominant role during the intraoperative period. This is evident in the National Surgical Quality Improvement Program (NSQIP) where traditional preoperative cardiac risk factors, lost their significance once intraoperative risk factors were considered [7]. We tested this hypothesis in a recent meta-analysis [8] where we aimed to determine which preoperative cardiac risk factors remained predictive of adverse cardiac events when taking into account independent intraoperative risk factors
Using the PICOT question structure [9] we framed the research question as: ‘Which intraoperative risk factors during non-cardiac surgery have been independently associated with adverse cardiac complications during the perioperative time period?’ The Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines were followed for this review [10]
Summary
Patients undergo cardiac preoperative evaluation to identify those at risk of adverse perioperative cardiac events. It is useful at excluding patients at risk of MACE (through an absence of known cardiac risk factors) [4], but it does not perform adequately in identifying patients at risk of MACE [4,5] This may be partly explained by the complexity of the pathophysiology of perioperative cardiac events [6] (that is, sympathetic activation, hypoxia, procoagulation, the stress response). Most of these factors play a dominant role during the intraoperative period (and after risk stratification with the RCRI). This is evident in the National Surgical Quality Improvement Program (NSQIP) where traditional preoperative cardiac risk factors, lost their significance once intraoperative risk factors were considered [7]
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