Introduction: Cardiopulmonary bypass (CPB) is often associated with post-operative vascular disturbance leading to organ dysfunction. Conventional monitoring metrics (i.e. blood pressure, heart rate) focus on the macrocirculation without insight to the microcirculation, and inadequate oxygen delivery at the cellular level still occurs. Prior studies have evaluated the microcirculation by imaging the sublingual and buccal mucosa, but these techniques are limited by the need for deep sedation. This study assesses the feasibility of nailfold capillaroscopy to evaluate microvascular changes in pediatric patients undergoing CPB and explores the association between perfused vessel density (PVD) and branchpoint density (BP) with post-operative organ dysfunction, defined by pediatric sequential organ failure assessment (pSOFA) score and serum lactate. Methods: A prospective, single center, observational study of patients < 18 years requiring CPB. Nailfold capillary images were obtained for each patient at three time points: pre-operatively (T0) and twice post-operatively (T1, T2). The PVD and BP of each image was quantified. Data were analyzed to investigate the association between PVD and BP with two outcome variables: pSOFA score and lactate. Results: 31 patients were enrolled and 25 patients (80.6%) consisting of 75 clinical encounters were analyzed. Median patient age was 6 months. There was a significant association between PVD and pSOFA score at the population level estimate coefficient 0.15, 95% CI (0.01, 0.03), p = 0.04. There was also a significant association between BP and pSOFA at the population level estimate coefficient 0.01, 95% CI (0, 0.02), p = 0.03. There was not a significant association between PVD nor BP with the outcome of lactate. Conclusions: Nailfold capillaroscopy is a feasible, non-invasive method of evaluating the microcirculation in pediatric patients who undergo CPB. Higher indices of vascular complexity (BP and PVD) were associated with worse post-operative organ dysfunction, perhaps suggesting more capillary recruitment as compensation in a state of critical illness. Larger studies with inclusion of a healthy control group may provide a better understanding of how microcirculatory monitoring may aid in peri-operative clinical care.
Pritchett et al. (Sun,) studied this question.