Pulsatility does not change cerebral oxygenation during cardiopulmonary bypass.
BACKGROUND
To determine the effect of pulsatility during cardiopulmonary bypass (CPB) on cerebral oxygenation, we measured oxyhaemoglobin (HbO2), deoxyhaemoglobin (Hb) and oxidised cytochrome aa3 (CtO2) with near-infrared spectroscopy (NIRS) in 14 patients electively scheduled for cardiac surgery.


METHODS
Cerebral oxygenation was measured during steady state CPB at a core temperature of 32 degrees C. Non-pulsatile flow and pulsatile flow were performed for 10 min each.


RESULTS
After 14 min of CPB, HbO2, Hb and CtO2 were significantly below prebypass values. HbO2 and CtO2 did not alter with changing flow patterns. Hb significantly increased both during the period of nonpulsatile (median: -0.7 vs. 0.25 micromol/l; P<0.05) and pulsatile flow (median: 0.25 vs. 0.5 micromol/l; P<0.001). This increase was independent of flow pattern.


CONCLUSIONS
Neither oxygenated haemoglobin, nor intracellular oxygenation, represented by CtO2, indicated a beneficial effect of pulsatile perfusion during hypothermic CPB. These results, however, are only valid for short time effects within 10 min before rewarming from CPB and patients without flow-limiting stenoses of the carotid artery.
Grubhofer
G
G
Department of Cardiothoracic and Vascular Anaesthesia & Intensive Care, University Clinic of Vienna, Austria. Georg.Grubhofer@univie.ac.at
Mares
P
P
Rajek
A
A
Müllner
T
T
Haisjackl
M
M
Dworschak
M
M
Lassnigg
A
A
D001921:Brain / Q000378:metabolism*; D002315:Cardiopulmonary Bypass / Q000379:methods; D002560:Cerebrovascular Circulation; D003576:Electron Transport Complex IV / Q000097:blood; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000032:analysis; D011673:Pulsatile Flow; D019265:Spectroscopy, Near-Infrared
D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D003576:Electron Transport Complex IV; D010100:Oxygen