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

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.

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.

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.

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.