Oxygenation within the first 120 h following coronary artery bypass grafting. Influence of systemic hypothermia (32 degrees C) or normothermia (36 degrees C) during the cardiopulmonary bypass: a randomized clinical trial.
BACKGROUND
Lung function is often impaired after cardiac surgery performed under cardiopulmonary bypass (CPB). Normothermic CPB has become more common, but it remains unknown whether it reduces post-operative lung function compared with hypothermic CPB. The aim of this study was to investigate oxygenation within the first 120 h after systemic hypothermia and normothermia under CPB.


METHODS
Thirty patients undergoing coronary artery bypass grafting (CABG) were randomized to either hypothermic (32 degrees C) or normothermic (36 degrees C) CPB. Oxygenation was studied by a simple method for the estimation of intrapulmonary shunt and ventilation-perfusion (V/Q) mismatch pre-operatively and 4, 48 and 120 h post-operatively by changing Fio2 in four to six steps. V/Q mismatch was described with DeltaPo2 (normal values, 0-2.38 kPa).


RESULTS
Shunt and V/Q mismatch (DeltaPo2) increased post-operatively in both groups (P<0.01), with no differences between the groups, and with the nadir values 48 h after surgery, i.e. shunt of 15% (5.8-25%) and DeltaPo2 of 3.0 kPa (0.8-14 kPa) [values given as median (range)].


CONCLUSIONS
Impaired oxygenation is prevalent and prolonged following CABG, with equal intensity after hypothermic and normothermic CPB.
Rasmussen
B S
BS
Department of Anaesthesia, Centre for Cardiovascular Research, Aalborg Hospital, Aarhus University, Denmark. an.bsr@nja.dk
Sollid
J
J
Rees
S E
SE
Kjaergaard
S
S
Murley
D
D
Toft
E
E
D000328:Adult; D000368:Aged; D001831:Body Temperature; D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011659:Pulmonary Gas Exchange
D002245:Carbon Dioxide; D010100:Oxygen