Flooding the Surgical Field With Carbon Dioxide During Open Heart Surgery Improves Segmental Wall Motion

Air embolization to the coronary arteries is a common cause of myocardial ischemia during open heart surgery. Carbon dioxide emboli may be absorbed faster than air emboli. In this randomized, double blind, placebo-controlled trial, we determined that flooding the surgical field with carbon dioxide is associated with improved myocardial function assessed by transesophageal echocardiography. Forty-three valve surgeries were randomized to insufflation of 6 L/min of carbon dioxide or placebo through a Jackson Pratt drain into the pericardium during cardiopulmonary bypass. During rewarming, as pulse pressure rose above 10 mmHg, two observers graded severity of bubbles in the left heart. Two other observers evaluated wall motion in the transgastric midpapillary short axis view of the left ventricle using transesophageal echocardiography. Compared with baseline average scores among all walls (carbon dioxide, 1.42 +/- 0.46; placebo, 1.39 +/- 0.45), worsening of wall motion was less at 1 minute in the carbon dioxide (1.60 +/- 0.62) than in the placebo group (1.95 +/- 0.54; p = 0.0266). Better wall motion tended to persist in the carbon dioxide group at 10 (1.58 +/- 0.59 vs. 1.77 +/- 0.6) and 60 minutes (1.61 +/- 0.45 vs. 1.66 +/- 0.58). Particularly, the inferior wall tended toward transiently better function in the carbon dioxide group (at baseline and 1, 10, and 60 minutes: placebo, 1.62 +/- 0.72, 2.68 +/- 0.79, 2.48 +/- 0.95, 2.10 +/- 0.9 vs. 1.88 +/- 0.97, 2.33 +/- 1.1, 2.18 +/- 0.96, 2.20 +/- 0.94). Preoperative characteristics, length of bypass, anesthesia time, hospitalization, and intensive care unit stay were not different. We recommend administration of carbon dioxide because it may improve myocardial function. We describe how to avoid adverse effects of giving carbon dioxide by filtering the supply, continuously managing its level during bypass, increasing sweep speeds, continuously analyzing the in-line blood gas, and avoiding suctioning gases in the field into the cardiotomy reservoir.