Nanette M. Schwann

Lack of Effectiveness of the Pulmonary Artery Catheter in Cardiac Surgery

BACKGROUND: The pulmonary artery catheter (PAC) continues to be used for monitoring of hemodynamics in patients undergoing coronary artery bypass graft (CABG) surgery despite concerns raised in other settings regarding both effectiveness and safety. Given the relative paucity of data regarding its use in CABG patients, and given entrenched practice patterns, we assessed the impact of PAC use on fatal and nonfatal CABG outcomes as practiced at a diverse set of medical centers. METHODS: Using a formal prospective observational study design, 5065 CABG patients from 70 centers were enrolled between November 1996 and June 2000 using a systemic sampling protocol. Propensity score matched-pair analysis was used to adjust for differences in likelihood of PAC insertion. The predefined composite endpoint was the occurrence of any of the following: death (any cause), cardiac dysfunction (myocardial infarction or congestive heart failure), cerebral dysfunction (stroke or encephalopathy), renal dysfunction (dysfunction or failure), or pulmonary dysfunction (acute respiratory distress syndrome). Secondary variables included treatment indices (inotrope use, fluid administration), duration of postoperative intubation, and intensive care unit length of stay. After categorization based on PAC and transesophageal echocardiography use (both, neither, PAC only, transesophageal echocardiography only), we performed the primary analysis contrasting PAC only and neither (total, 3321 patients), from which propensity paring yielded 1273 matched pairs. RESULTS: The primary endpoint occurred in 271 PAC patients versus 196 without PAC (21.3% vs.15.4%; adjusted odds ratio [AOR], 1.68; 95% confidence interval [CI], 1.24 to 2.26; P < 0.001). The PAC group had an increased risk of all-cause mortality, 3.5% vs 1.7% (AOR, 2.08; 95% CI, 1.11 to 3.88; P = 0.02) and an increased risk of cardiac (AOR, 1.58; 95% CI, 1.14 to 2.20; P = 0.007), cerebral (AOR, 2.02; 95% CI, 1.08 to 3.77; P = 0.03) and renal (AOR, 2.47; 95% CI, 1.68 to 3.62; P < 0.001) morbid outcomes. PAC patients received inotropic drugs more frequently (57.8% vs 50.0%; P < 0.001), had a larger positive IV fluid balance after surgery (3220 mL vs 3022 mL; P = 0.003), and experienced longer time to tracheal extubation (15.40 hours [11.28/20.80] versus 13.18 hours [9.58/19.33], median plus Q1/Q3 interquartile range; P < 0.0001). Use of PAC was also associated with prolonged intensive care unit stay (14.5% vs 10.1%; AOR, 1.55; 95% CI, 1.06 to 2.27; P = 0.02). CONCLUSIONS: Use of a PAC during CABG surgery was associated with increased mortality and a higher risk of severe end-organ complications in this propensity-matched observational study. A randomized controlled trial with defined hemodynamic goals would be ideal to either confirm or refute our findings.

Predictive value of the National Institutes of Health Stroke Scale and the Mini-Mental State Examination for neurologic outcome after coronary artery bypass graft surgery

OBJECTIVE We intended to define the role of the National Institutes of Health Stroke Scale and the Mini-Mental State Examination in identifying adverse neurologic outcomes in a large international sample of patients undergoing cardiac surgery. METHODS We evaluated 4707 patients undergoing cardiac surgery with cardiopulmonary bypass at 72 centers in 17 countries between November 1996 and June 2000. Prespecified overt neurologic outcomes were categorized as type I (clinically diagnosed stroke, transient ischemic attack, encephalopathy, or coma) or type II (deterioration of intellectual function). The National Institutes of Health Stroke Scale and Mini-Mental State Examination were administered preoperatively and on postoperative day 3, 4, or 5. Receiver operating characteristic curves were plotted to determine the predictive value of worsening in National Institutes of Health Stroke Scale and Mini-Mental State Examination scores with respect to type I and II outcomes. RESULTS The receiver operating characteristic area under the curve for changes in National Institutes of Health Stroke Scale score (n = 4620) was 0.89 for type I outcomes and 0.66 for type II outcomes. A 1-point worsening in National Institutes of Health Stroke Scale score provided excellent discrimination (86% specificity; 84% sensitivity) of type I outcomes. The receiver operating characteristic area under the curve for changes in Mini-Mental State Examination score (n = 4707) was 0.75 for type I outcomes and 0.71 for type II outcomes. A 2-point worsening in Mini-Mental State Examination score provided only fair discrimination (73% specificity; 62% sensitivity) of type II outcomes. CONCLUSION We used baseline controls and postoperative worsening in National Institutes of Health Stroke Scale and Mini-Mental State Examination scores to predict both serious adverse neurologic outcome and deterioration of intellectual function. Our findings provide the only reference for evaluating these tests that are used in cardiac surgical clinical trials.

The Effect of Beta-Blocker Dosing Strategy on Regulation of Perioperative Heart Rate and Clinical Outcomes in Patients Undergoing Vascular Surgery: A Randomized Comparison

The optimal dosing strategy for perioperative beta-blockers to safely achieve recommended target heart rates (HRs) by current guidelines is not well defined. An HR-titrated perioperative beta-blocker dosing regimen versus a fixed-dose regimen was assessed by clinical outcomes, postoperative heart rate, and beta-blocker-related complications. Patients (n = 64) scheduled to undergo moderate- to high-risk vascular surgery and without contraindications to beta-blockade were randomized to either a fixed-dose or HR-titrated beta-blocker dosing schedule. Clinical outcomes and HRs were followed immediately preoperatively to 24 hr postoperatively. A difference in mean HR between the two dosing arms was significant immediately postoperatively (70.1 vs. 58.2 bpm for fixed dose and HR-titrated arms, respectively; p = 0.012) but at no other time points. However, the HR-titrated strategy led to a significant reduction in the percentage of HR measurements >80 bpm (34.5% vs. 16.1%, p < 0.001) and to a significant reduction in absolute HR change (17.5 vs. 22.5 bpm, p = 0.034). There were no significant differences in the occurrence of asymptomatic hypotension between the two study arms, and no beta-blocker-related adverse events occurred in either study arm. An aggressive, HR-titrated perioperative beta-blocker dosing strategy was associated with more consistent maintenance of postoperative HRs within the range recommended by current guidelines and did not result in increased drug-related adverse events. The question of what is the best perioperative beta-blocker dosing regimen warrants further evaluation in a large-scale clinical trial.