Abstract
OBJECTIVES: Optimal blood pressure goals during cardiopulmonary bypass (CPB) remain uncertain and new metrics to individualize perfusion targets are needed. Critical closing pressure (Pcrit) is a fundamental property of the arterial circulation related to vascular tone and represents the outflow pressure impacting flow across the systemic circulation. We examined Pcrit as a prognostic marker of acute kidney injury (AKI). DESIGN: Retrospective cohort study. SETTING: Single tertiary care hospital PARTICIPANTS: We included 1,038 adult cardiac surgery patients who underwent CPB. INTERVENTIONS: Pcrit was calculated using arterial waveform data before initiation of CPB. Pcrit was examined in relation to incidence of stage 2 or higher postoperative AKI according to standard Kidney Disease Improving Global Outcomes definitions. MEASUREMENTS AND MAIN RESULTS: Of the 1,038 patients included in the study, 50 (5%) experienced AKI. Patients who suffered AKI had significantly higher preoperative risk factors, including higher incidence of severe chronic kidney disease and higher Society of Thoracic Surgeons risk score (p < 0.01). They also had longer operative times and longer cross-clamp times (p < 0.01). All patients were maintained at similar mean arterial pressure while on CPB. Patients who suffered AKI had a significantly higher prebypass Pcrit than those who did not (49.0 mmHg vs 44.1 mmHg; p = 0.018). In a multivariate regression, Pcrit remained a significant predictor, representing a 16% increased risk of AKI for each 5 mmHg increase in prebypass Pcrit (p = 0.011). CONCLUSIONS: A higher prebypass Pcrit is associated with a significantly higher incidence of postoperative AKI. Future study is warranted to investigate using intraoperative Pcrit to determine a personalized blood pressure goal during CPB.