Cardiovascular events in the postanesthesia care unit: contribution of risk factors

Background — The purpose of this study was to determine the relationship of four postanesthesia care unit (PACU) cardiovascular events to long-term outcomes (unplanned critical care admission or mortality) and to evaluate the contribution of anesthetic management compared with other perioperative factors in predicting these events.

Methods — For patients admitted to the PACU after receiving general anesthesia (n = 18,380), the risk of long-term outcomes was examined for patients in the PACU with hypertension, tachycardia, bradycardia, or hypotension. Using logistic regression (P < 0.05), risk factors (grouped as patients, surgical, anesthetic, operating room observations, and other PACU observations) for each cardiovascular event were determined. For each factor grouping, the relative contributions to each cardiovascular event were compared using maximum likelihood chi-square analysis.

Results — Patients in the PACU with hypertension or tachycardia had more unplanned critical care admissions (2.6% and 4.0% vs. 0.2% for patients with no events) and greater mortality (1.9% and 2.3% vs. 0.3% and 0.4%) (P < 0.01). For PACU hypertension (rate 2.0%), age, smoking, renal disease, female gender, and angina were significant risk factors. For PACU tachycardia (0.9%), intraoperative tachycardia and dysrhythmia were the major contributors. Patient factors also increased the risk of bradycardia (2.5%); namely age, ASA physical status 1 or 2, and preoperative beta blocker therapy. For hypotension (2.2%), duration of surgery > 2 h, completion after 6 PM, and gynecologic intraabdominal procedures were significant risk factors. Compared to patient, surgical, intraoperative, or PACU observations, anesthetic factors studied (premedication, induction agent, ventilation, use of opioids) provided only a small contribution in predicting these events.

Conclusions — Hypertension and tachycardia in the PACU, although infrequent, are associated with increased risk of unplanned critical care admission and mortality. Patient, surgical, intraoperative, or PACU observations contribute more to cardiovascular events in the PACU than do differences in anesthetic management identified in this study.