Combining low inspired oxygen and carbon dioxide during mechanical ventilation for the Norwood procedure.
BACKGROUND
Staged reconstruction has become the preferred approach for treating neonates with hypoplastic left heart syndrome (HLHS). The haemodynamic instability of a single ventricle providing blood flow in parallel to the systemic and the pulmonary circulation, combined with the effects of cardiopulmonary bypass (CPB), results in precarious perioperative conditions. The two ventilatory manoeuvres commonly used for increasing pulmonary vascular resistance are (i) decreasing the fraction of inspired oxygen to < 0.21 and (ii) adding carbon dioxide (CO2) to the ventilatory circuit. Whether molecular nitrogen (N2) or CO2 is used in these situations is a matter of physician and institutional preference. The effect of the two modalities in combination has not been studied in depth.


METHODS
This prospective observational study was designed to look at the effects of adding inhaled CO2 to children with HLHS who were already on a hypoxic mixture during the immediate perioperative period.


RESULTS
Twelve suitable neonates were enrolled in the study. Combining the two ventilatory modalities had an additive effect. The effect was more significant in the prebypass (83% of patients) compared with the postbypass period (25% of patients).


CONCLUSIONS
Low inspired oxygen and CO2 have an additive vasoconstrictive effect on the pulmonary vessels. The use of both of these ventilatory manoeuveres is less effective postoperatively compared with the prebypass period.
Keidan
Ilan
I
Department of Anesthesiology, Chaim Sheba Medical Center, Sackler School of Medicine, Tel-Aviv University, Tel-Hashomer, Israel. keidan@012.net.il
Mishaly
David
D
Berkenstadt
Haim
H
Perel
Azriel
A
D002245:Carbon Dioxide / Q000627:therapeutic use*; D006348:Cardiac Surgical Procedures; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000601:surgery*; D007231:Infant, Newborn; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods
D002245:Carbon Dioxide