Cerebral Oximetry Monitoring to Maintain Normal Cerebral Oxygen Saturation during High-risk Cardiac Surgery: A Randomized Controlled Feasibility Trial.

BACKGROUND: Cerebral oxygen desaturation during cardiac surgery has been associated with adverse perioperative outcomes. Before a large multicenter randomized controlled trial (RCT) on the impact of preventing desaturations on perioperative outcomes, the authors undertook a randomized prospective, parallel-arm, multicenter feasibility RCT to determine whether an intervention algorithm could prevent desaturations. METHODS: Eight Canadian sites randomized 201 patients between April 2012 and October 2013. The primary outcome was the success rate of reversing cerebral desaturations below 10% relative to baseline in the intervention group. Anesthesiologists were blinded to the cerebral saturation values in the control group. Intensive care unit personnel were blinded to cerebral saturation values for both groups. Secondary outcomes included the area under the curve of cerebral desaturation load, enrolment rates, and a 30-day follow-up for adverse events. RESULTS: Cerebral desaturations occurred in 71 (70%) of the 102 intervention group patients and 56 (57%) of the 99 control group patients (P = 0.04). Reversal was successful in 69 (97%) of the intervention group patients. The mean cerebral desaturation load (SD) in the operating room was smaller for intervention group patients compared with control group patients (104 [217] %.min vs. 398 [869] %.min, mean difference, -294; 95% CI, -562 to -26; P = 0.03). This was also true in the intensive care unit (P = 0.02). There were no differences in adverse events between the groups. CONCLUSIONS: Study sites were successful in reversal of desaturation, patient recruitment, randomization, and follow-up in cardiac surgery, supporting the feasibility of conducting a large multicenter RCT.

Risk of intraoperative hypotension with loop diuretics: a randomized controlled trial.

BACKGROUND: There is growing concern regarding the safety of blood pressure-lowering medications administered during the perioperative period. Whether loop diuretics also induce intraoperative hypotension is uncertain. Our objective was to compare the effects of continuing or withholding furosemide on the day of noncardiac elective surgery on intraoperative hypotension among chronic users of furosemide. METHODS: A double blind, randomized, placebo controlled trial was conducted at 3 North American university centers between September 2000 and December 2006. Participants were randomly assigned in a 1:1 ratio to receive either furosemide or placebo on the day of surgery. The primary outcome was risk of developing intraoperative hypotension. A priori secondary outcomes included risk of heart failure; composite cardiovascular event (myocardial infarction, arrhythmia, stroke or transient ischemic attack, or death); and change in renal function and electrolytes. RESULTS: Of the 212 patients enrolled, 193 patients underwent surgery. There was no significant difference in risk of developing intraoperative hypotension between the furosemide (49%) and placebo (51.9%) groups (relative risk [RR], 0.95; 95% confidence interval [CI], 0.72-1.24; P = .78). The intraoperative administration of vasopressors and fluids were similar between both groups. The risk of developing postoperative cardiovascular events was not significantly different between those randomized to furosemide (4.8%) or placebo (2.8%) (RR, 1.73; 95% CI, 0.42-7.06; P = .49). There was no significant difference in renal function or electrolytes between the 2 groups. CONCLUSION: Among elective, noncardiac surgeries in patients chronically treated with furosemide, the administration of furosemide on the day of surgery did not significantly increase the risk for intraoperative hypotension.