Warm humidified CO2 insufflation improves pericardial integrity for cardiac surgery: a randomized control study

BACKGROUND: Flooding the surgical field with dry cold CO2 during open-chamber cardiac surgery has been used to mitigate air entrainment into the systemic circulation. However, exposing epithelial surfaces to cold, dry gas causes tissue desiccation. This randomized controlled study was designed to investigate whether the use of humidified warm CO2 insufflation into the cardiac cavity could reduce pericardial tissue damage and the incidence of micro-emboli when compared to dry cold CO2 insufflation. METHODS: Forty adult patients requiring elective open-chamber cardiac surgery were randomized to have either dry cold CO2 insufflation via a standard catheter or humidified warm CO2 insufflation via the HumiGard device (Fisher & Paykel Healthcare, Panmure, Auckland, New Zealand). The primary endpoint was biopsied pericardial tissue damage, assessed using electron microscopy. We assessed the percentage of microvilli and mesothelial damage, using a damage severity score (DSS) system. We compared the proportion of patients who had less damage, defined as DSS<2. Secondary endpoints included the severity of micro-emboli, by visual assessment of bubble load on trnnsesophageal echocardiogram; lowest near infrared spectroscopy; total de-airing time; highest cardio-pulmonary bypass sweep speed; hospital length of stay and complications. RESULTS: A higher proportion of patients in the humidified warm CO2 group displayed conserved microvilli (47% its. 11%, P=1.03) and preserved mesothelium (42% vs. 5%, P=0.02) compared to the control group. There were no differences in the secondary outcomes. CONCLUSIONS: Humidified warm CO2 installation significantly reduced pericardial epithelial damage when compared to dry cold CO2 insufflation in open-chamber cardiac surgery. Further studies are warranted to investigate its potential clinical benefits.