Vascular Occlusion Test to Dynamically Assess Microcirculation During Normothermic Pulsatile Cardiopulmonary Bypass
Abstract
Objective
To evaluate parameters of the vascular occlusion test (VOT) before, during, and after pulsatile cardiopulmonary bypass (CPB).
Design
Prospective, observational study.
Setting
Single-center university hospital.
Participants
Adult patients undergoing elective cardiac surgery with pulsatile CPB.
Interventions
An oximeter sensor and adult-sized pneumatic tourniquet were positioned at the right forearm. A VOT with a predefined ischemic time of 3 minutes was performed before, during, and after CPB. Changes in tissue oxygen saturation were recorded.
Measurements and Main Results
Thirty-four patients who underwent cardiac surgery were enrolled in the study. The lowest tissue oxygen saturation measured during the ischemic challenge differed among all 3 stages of surgery, with median values of 62.9% before, 57.5% during, and 59.3% after perfusion (p<0.05). Both occlusion (p<0.001) and reperfusion (p<0.05) slopes were steeper after bypass compared with before initiating bypass, whereas the reperfusion time remained constant among the different time points.
Conclusions
The microcirculatory function as demonstrated by changes in VOT parameters was enhanced during and after normothermic pulsatile CPB. Clinical relevance, however, needs to be further explored.