A Pilot Study Comparing Aortic Valve Area Estimates Derived from Fick Cardiac Output with Estimates Based on Cheetah-NICOM Cardiac Output.

Cardiac output during cardiac catheterization is often estimated using the modified Fick method (COFick). In this proof-of-concept, prospective non-randomized study carried out in a single academic healthcare centre, we examined whether replacing COFick in the Gorlin formula with Cheetah-NICOM monitor cardiac output (COCheetah) could produce an accurate and precise estimate of aortic valve area in patients with severe aortic stenosis. In twenty-six subjects, COFick and COCheetah were obtained concurrently. A spot and 3-minute running average of COCheetah was used. Bland and Altman analysis was used to derive bias, 95% limits of agreement (LOA) and confidence intervals (CI). The mean difference (bias) between AVACheetah (average) and AVAFick was 0.11 cm2 and the 95% LOA were ±0.42 cm2. The 95% CI of the bias was 0.02-0.2 cm2. The bias and 95% LOA of AVACheetah (spot value) were 0.14 ± 0.42cm2, with a 95% CI of 0.06-0.23 cm2. No proportional bias was present. AVACheetah thus appears to be a reasonably accurate measure of AVA in patients with severe aortic stenosis compared to AVAFick measured using a modified Fick CO. However, the limits of agreement were not narrow enough to consider AVACheetah and AVAFick interchangeable.

Elevated Pulse Pressure in Anesthetized Subjects Before Cardiopulmonary Bypass Is Associated Strongly With Postoperative Acute Kidney Injury Stage.

OBJECTIVE: To investigate whether pulse pressure (PP) in anesthetized patients undergoing cardiac surgery before and after cardiopulmonary bypass (CPB) is associated with higher postoperative acute kidney injury (AKI) stage. DESIGN: Retrospective cohort of 597 patients undergoing cardiac surgery. SETTING: Single academic health care center. PARTICIPANTS: Adult patients undergoing cardiac surgery requiring CPB (coronary artery bypass grafting, valve, aortic, or combined surgery). INTERVENTIONS: Pulse pressure was assessed during 3 time periods: pre- and post-CPB, and in the first postoperative hour in the intensive care unit. Pulse pressure, patient characteristics, and intraoperative variables were evaluated using univariable generalized estimating equation analysis for a relationship with AKI stage. Significant risk factors from the univariable analysis then were evaluated in a multivariable generalized estimating equation analysis. Acute kidney injury stage was defined using the Acute Kidney Injury Network criteria. PRIMARY OUTCOME: Stage of postoperative AKI. MEASUREMENTS AND MAIN RESULTS: Intraoperative prebypass PP was associated independently and significantly with postoperative AKI stage (odds ratio 1.0107; 95% Confidence Interval, 1.0046-1.0168; p = 0.0005). For every 1-mmHg increase in PP, the odds of a higher AKI stage increased 1.07%. The 2 other periods were not found to be significant predictors of AKI stage. CONCLUSION: During general anesthesia prior to initiation of CPB, elevated PP is significantly predictive of postoperative AKI stage. This finding merits further research.