Pulmonary artery catheters, transesophageal echocardiography and mortality in coronary artery bypass grafting in Ontario
Problem: There is controversy in the literature as to the extent and type of invasive monitoring that is appropriate for patients undergoing coronary artery bypass grafting (CABG). The use of pulmonary artery catheterization (PAC) has been associated with increased postoperative mortality compared to central venous pressure monitoring (CVP), and the association between transesophageal echocardiography (TEE) and mortality has not been examined. There is limited Canadian data examining these relationships. Methods: A retrospective cohort study was undertaken using administrative database holdings at the Institute for Clinical Evaluative Sciences to identify patients undergoing CABG over a ten-year period (October 1, 2001 to September 30, 2011) and describe their comorbidities and exposure to invasive monitoring on the day of surgery. Logistic regression was used to assess predictors of monitor use and to examine the association between monitoring type on the day of surgery and 30-day mortality. Results: There were 52,202 patients in the cohort. PAC use was the most common (67.2%), followed by PAC and TEE combined (26.5%), CVP alone (3.7%) and TEE alone (2.6%). Patient comorbidities and institution were important predictors of monitor use in any given patient. Over the study period, 638 patients died within 30 days of CABG (1.22%). Overall, no monitor was statistically associated with increased risk of 30-day mortality compared to CVP. In subgroup analysis, exposure to PAC/TEE was associated with increased mortality compared to PAC alone (OR 1.48, 95% CI [1.22, 1.80]. Conclusion: Clinicians did not respond to the existing PAC literature by decreasing this monitor’s use. Despite this, there was no harmful association found in patients exposed to PAC compared to CVP. Since the addition of TEE to PAC was associated with increased mortality in this cohort, it is recommended that clinicians and institutions critically evaluate the routine need for this monitor in patients undergoing CABG.