Monitoring Microcirculatory Blood Flow during Cardiopulmonary Bypass in Paediatric Cardiac Surgery Patients as a Predictor for Anaerobic Metabolism.

Introduction: Improving tissue oxygenation is one of most important tasks in management of low cardiac output. Central venous oxygen saturation (ScvO) and lactate are established criteria for monitoring the adequacy of tissue oxygenation. The venous-to-arterial carbon dioxide difference [P(v-a)CO] is inversely associated with cardiac output.

Aim: To study the use of P(v-a)CO/C(a-v)O ratio as a marker of low cardiac output during Cardiopulmonary Bypass (CPB) in paediatric cardiac surgical patients.

Materials And Methods: The present study was a prospective observational study conducted over a period of nine months from 1 August 2015 to 30 April 2016. A total of 110 children were enrolled, who underwent CPB during cardiac surgery. The CPB time, Mean Arterial Pressure (MAP), flow rate, cross clamp time, were recorded for all the patients as well as Arterial Blood Gas (ABG) and Venous Blood Gas (VBG) were checked at four different points of time: 1) Before CPB, 2) 10 minutes after initiation of CPB, 3) 30 minutes on CPB and 4) off CPB.

Results: The results indicated that Receiver Operating Characteristic curve (ROC curve) at 30 minute of CPB time P(v-a)CO/C(a-v)O was more specific and sensitive than lactate to detect anaerobic metabolism. Decrease platelet count was significant on second postoperative day.

Conclusion: The present study suggests the use of P(v-a)CO/C(a-v)O ratio as a marker to detect low flow on CPB. Our study was single centric and with a small size, studies involving large population and multiple centers are required to support the recent findings.