Original Article

Acid-base status of the blood contained in the cardiotomy reservoir during deep hypothermic circulatory arrest at 18 °C

¹ Department of Anesthesiology, Marie Lannelongue Hospital, Paris Saint Joseph Hospital, 133 Avenue de la Résistance, 92350 Le Plessis Robinson, France
² Cardiothoracic Intensive Care Unit, Marie Lannelongue Hospital, Paris Saint Joseph Hospital, 133 Avenue de la Résistance, 92350 Le Plessis Robinson, France
³ Department of Vascular and Thoracic Surgery, Marie Lannelongue Hospital, Paris Saint Joseph Hospital, 133 Avenue de la Résistance, 92350 Le Plessis Robinson, France
⁴ Perfusionist Team, Department of Anesthesiology, Marie Lannelongue Hospital, Paris Saint Joseph Hospital, 133 Avenue de la Résistance, 92350 Le Plessis Robinson, France

^* Corresponding author: menes.diop@gmail.com

Received: 10 February 2025
Accepted: 27 April 2025

Abstract

Background: During deep hypothermic circulatory arrest (DHCA) for pulmonary artery endarterectomy (PAE), the blood volume stored in the cardiotomy reservoir circulates through the oxygenator via the arterial shunt line, where it remains oxygenated and decarboxylated. The aim of the study was to investigate the change in the acid-base balance of the blood contained in the cardiotomy reservoir during DHCA. Methods: A four-month retrospective analysis was conducted on patients undergoing PAE. The sweep gas inflow and the inspired fraction of O₂ were kept constant throughout the duration of DHCA. Arterial blood gases were sampled at the beginning and at the end of the DHCA and were analyzed according to the alpha-stat and pH-stat strategies. Results: Twenty-four patients were included with a mean age of 59.2 (±15.7) years. The mean duration of DHCA was 15.2 (±4.1) min and the mean sweep gas inflow was 1.4 (±0.8) L/min. Initial pH and PaCO₂ were 7.31 (±0.09) and 43.2 (±9.9) mmHg, respectively, and final pH and PaCO₂ were 7.51 (± 0.14), p < 0.001 and 23.4 (±11.9) mmHg, p < 0.001. There was a significant correlation between the sweep gas inflow and the post-DHCA pH (r = 0.797). Conclusion: The pH increases significantly during the DHCA according to the sweep gas inflow. Decreasing the sweep gas inflow between 0.5 and 1.0 L/min allows for limiting the pH variation during the DHCA period.