Arterial Catheters for Early Detection and Treatment of Hypotension During Major Noncardiac Surgery: A Randomized Trial.

BACKGROUND: Continuous blood pressure monitoring may facilitate early detection and prompt treatment of hypotension. We tested the hypothesis that area under the curve (AUC) mean arterial pressure (MAP) <65 mm Hg is reduced by continuous invasive arterial pressure monitoring. METHODS: Adults having noncardiac surgery were randomly assigned to continuous invasive arterial pressure or intermittent oscillometric blood pressure monitoring. Arterial catheter pressures were recorded at 1-minute intervals; oscillometric pressures were typically recorded at 5-minute intervals. We estimated the arterial catheter effect on AUC-MAP <65 mm Hg using a multivariable proportional odds model adjusting for imbalanced baseline variables and duration of surgery. Pressures <65 mm Hg were categorized as 0, 1-17, 18-91, and >91 mm Hg × minutes of AUC-MAP <65 mm Hg (ie, no hypotension and 3 equally sized groups of increasing hypotension). RESULTS: One hundred fifty-two patients were randomly assigned to arterial catheter use and 154 to oscillometric monitoring. For various clinical reasons, 143 patients received an arterial catheter, while 163 were monitored oscillometrically. There were a median [Q1, Q3] of 246 [187, 308] pressure measurements in patients with arterial catheters versus 55 (46, 75) measurements in patients monitored oscillometrically. In the primary intent-to-treat analysis, catheter-based monitoring increased detection of AUC-MAP <65 mm Hg, with an estimated proportional odds ratio (ie, odds of being in a worse hypotension category) of 1.78 (95% confidence interval [CI], 1.18-2.70; P = .006). The result was robust over an as-treated analysis and for sensitivity analyses with thresholds of 60 and 70 mm Hg. CONCLUSIONS: Intraoperative blood pressure monitoring with arterial catheters detected nearly twice as much hypotension as oscillometric measurements.

Long-Acting Patient-Controlled Opioids Are Not Associated With More Postoperative Hypoxemia Than Short-Acting Patient-Controlled Opioids After Noncardiac Surgery: A Cohort Analysis.

BACKGROUND: Opioids can contribute to postoperative desaturation. Short-acting opioids, titrated to need, may cause less desaturation than longer-acting opioids. We thus tested the primary hypothesis that long-acting patient-controlled intravenous opioids are associated with more hypoxemia (defined as an integrated area under a postoperative oxyhemoglobin saturation of 95%) than short-acting opioids. METHODS: This analysis was a substudy of VISION, a prospective cohort study focused on perioperative cardiovascular events (NCT00512109). After excluding for predefined criteria, 191 patients were included in our final analysis, with 75 (39%) patients being given fentanyl (short-acting opioid group) and 116 (61%) patients being given morphine and/or hydromorphone (long-acting opioid group). The difference in the median areas under a postoperative oxyhemoglobin saturation of 95% between short-acting and long-acting opioids was compared using multivariable median quantile regression. RESULTS: The short-acting opioid median area under a postoperative oxyhemoglobin saturation of 95% per hour was 1.08 (q1, q3: 0.62, 2.26) %-h, whereas the long-acting opioid median was 1.28 (0.50, 2.23) %-h. No significant association was detected between long-acting and short-acting opioids and median area under a postoperative oxyhemoglobin saturation of 95% per hour (P = .66) with estimated change in the medians of -0.14 (95% CI, -0.75, 0.47) %-h for the patients given long-acting versus short-acting IV patient-controlled analgesia opioids. CONCLUSIONS: Long-acting patient-controlled opioids were not associated with the increased hypoxemia during the first 2 postoperative days.