CLINICAL EFFICACY OF PULSATILE PERFUSION IN ELDERLY PATIENTS UNDERGOING CARDIAC SURGERY: hemodynamic energy, vascular reactivity, endothelial integrity and renal function

Objective(s): the superiority of pulsatile perfusion over non-pulsatile during short-term cardiopulmonary bypass (CPB) is still controversial. Elderly patients are the most sensible to the perfusion quality and could benefit from pulsatile CPB. The objective of the study was to analyze hemodynamic effects, vascular reactivity, endothelial integrity and renal function in elderly patients undergoing aortic valve replacement (AVR) with either pulsatile (PP) or non-pulsatile (NP) CPB. Methods: forty elderly patients (age 80±3 years old, EuroScore 5.9±1.5) with aortic valve stenosis were prospectively randomized for surgery with either PP or NP perfusion performed by centrifugal pump. Pulsatility was evaluated in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). Flow and pressure curves were recorded at 6 time-points during CPB with external flow-meters and collected in computer-based system. Systemic (SVRi), pulmonary (PVRi) vascular resistance, plasma markers of endothelial integrity (inter-cellular adhesive molecule–1 (ICAM-I), endothelin–1 (ET-1), von Willebrand factor (vWF)), erythrocyte e-NOS and urinary acute kidney injury makers (N-acetyl-β-D-glucosaminidase (NAG), kidney injury molecule–1 (KIM-1) and neutrophil gelatinase associated lipocalin (NGAL)) were collected during 24 hours of perioperative period together with pre- and postoperative creatinine clearance assessment. Results: In PP group, EEP calculated in patient’s radial artery was at average 7.3% higher than mean arterial pressure (MAP), which corresponded to an increase of 5150±2291 ergs/cm3 of SHE. In NP group EEP and MAP were equal. Mean perfusion pressure (55±9 mmHg in PP group vs 60±13 mm Hg in NP group) and flow (4.4±0.5 vs 4.3±0.4) showed no difference between the groups. SVRi was significantly lower during cross-clamp period in PP group until rewarming phase and just after removing of cross-clamp (ANOVA Group-time interaction p=0.06). PVRi was significantly lower in PP group after protamine administration and up to 2 hours in ICU (ANOVA Group-time interaction p=0.02). Lower vascular resistance induced by PP required higher perioperative dosages of vasopressor drugs infusion (p=0.01). ICAM, vWF, ET-I and eNOS showed marked variations at early post-CPB period without important difference between the groups. No significant difference between pre- and post-operative creatinine clearance was found in PP group (71 ± 26 vs 61 ± 35 mL/min p=0.951) while statistically significant decrement was observed in NP group (70 ± 28 vs 47 ± 16 mL/min p=0.001). PP group showed lowed mean urinary NAG level at 18 hours postoperatively (p=0.003) and lower NGAL levels at sternum closure (p=0.01) and 2 hours postoperatively (p=0.02). PP and NP patients were comparable in perioperative lactate levels, drainage blood loss, transfusion rates, ICU and hospital stay periods and early complications. Conclusions: In elderly patients undergoing aortic valve surgery, pulsatile flow provided a good organ perfusion with better preserved renal function. However, pulsatile perfusion induced lower systemic and pulmonary vascular resistance results in augmented postoperative vasopressor requirements.