Elimination of CO2 insufflation-induced hypercapnia in open heart surgery using an additional venous reservoir

Abstract

Abstract   OBJECTIVES Carbon dioxide (CO2) gas insufflation is used for continuous de-airing during open heart surgery. The aim was to evaluate if an additional separate venous reservoir eliminates CO2 insufflation-induced hypercapnia and keeps sweep gas flow of the oxygenator constant. METHODS A separate reservoir was used during cardiopulmonary bypass in addition to a standard venous reservoir. The additional reservoir received drained blood and CO2 gas continuously via a suction drain (1 l/min) and handheld suction devices from the surgical wound. CO2 gas was insufflated via a gas diffuser in the open wound at 10 l/min. In a cross-over design for each patient, gas and blood were either continuously drained from the additional to the standard venous reservoir or not. CO2 pressure in arterial blood (PaCO2) was measured after adjustment of sweep gas flow as necessary and after steady state of PaCO2 was observed. Mean values for each setup (median 4 times) for each patient were analysed with Wilcoxon rank-sum test. RESULTS Ten adult patients undergoing open aortic valve replacement were included. Median PaCO2 did not differ between setups (5.41; 5.29–5.57, interquartile range vs 5.41; 5.24–5.58, P = 0.92), whereas sweep gas flow (l/min) was lower (2.58; 2.50–3.16 vs 4.42; 4.0–5.40, P = 0.002) when CO2 gas was not drained from the additional to the standard reservoir. CONCLUSIONS An additional venous reservoir for the evacuation of blood from the open surgical wound eliminates CO2 insufflation-induced hypercapnia in open heart surgery keeping PaCO2 and sweep gas flow constant. This prevents possible CO2-induced hyperperfusion of the brain and decreases the risk of cerebral particulate embolization during CO2 insufflation for de-airing in open heart surgery. Clinical trial registration NCT04202575. IRB approval dat and number 2018-07-13 and 2018/1091-31.