TY - JOUR
T1 - The effect of ventilation on aortic blood gases during left ventricular ejection before separation from cardiopulmonary bypass
AU - Kronenfeld, Mark A.
AU - Lubarsky, David
AU - Feiler, Michael
AU - Galloway, Aubrey
AU - Thomas, Stephen J.
PY - 1989/1/1
Y1 - 1989/1/1
N2 - The time to begin ventilating a cardiac surgical patient recovering from hyperkalemic arrest is controversial. Those who advocate ventilating as soon as the left ventricle begins to eject believe that blood ejected from the left ventricle is likely to be hypoxic since it perfuses collapsed, nonventilated alveoli and that this may be the major blood supply perfusing the coronary arteries. The present study attempts to answer this question by sampling blood gases from the aorta in proximity to the coronary ostia in patients both before and after ventilation. Ten patients undergoing coronary artery bypass grafting using the left internal mammary artery were studied. Each patient served as his own control. Distal anastomoses were placed under hyperkalemic, hypothermic cardiac arrest. The aorta was unclamped, and an intrinsic or paced heart rate of 70 beats per minute was achieved. The heart was allowed to eject to a pulse pressure of 20 to 40 mmHg. Rectal temperatures were between 32°C and 34°C. Blood gases were drawn simultaneously from the proximal aortic root, radial artery, pulmonary artery, and the venous circuit of the cardiopulmonary bypass (CPB) machine. The lungs were then twice inflated with a sustained positive pressure of 30 cm H2O, and the patient was ventilated (10 mL/kg tidal volume, F1O2 1.0, 10 breaths per minute) for two minutes. Another set of blood gases was then obtained. Filling pressures, aortic systolic and diastolic pressures, and CPB flows were kept constant for both sets of samples. There was no significant difference in aortic root PaO2 attributable to ventilation. PCO2 was significantly lower, and pH was significantly higher in the ventilated group. Based on these results, the authors believe that it is a safe practice to withhold ventilation under the above-stated conditions.
AB - The time to begin ventilating a cardiac surgical patient recovering from hyperkalemic arrest is controversial. Those who advocate ventilating as soon as the left ventricle begins to eject believe that blood ejected from the left ventricle is likely to be hypoxic since it perfuses collapsed, nonventilated alveoli and that this may be the major blood supply perfusing the coronary arteries. The present study attempts to answer this question by sampling blood gases from the aorta in proximity to the coronary ostia in patients both before and after ventilation. Ten patients undergoing coronary artery bypass grafting using the left internal mammary artery were studied. Each patient served as his own control. Distal anastomoses were placed under hyperkalemic, hypothermic cardiac arrest. The aorta was unclamped, and an intrinsic or paced heart rate of 70 beats per minute was achieved. The heart was allowed to eject to a pulse pressure of 20 to 40 mmHg. Rectal temperatures were between 32°C and 34°C. Blood gases were drawn simultaneously from the proximal aortic root, radial artery, pulmonary artery, and the venous circuit of the cardiopulmonary bypass (CPB) machine. The lungs were then twice inflated with a sustained positive pressure of 30 cm H2O, and the patient was ventilated (10 mL/kg tidal volume, F1O2 1.0, 10 breaths per minute) for two minutes. Another set of blood gases was then obtained. Filling pressures, aortic systolic and diastolic pressures, and CPB flows were kept constant for both sets of samples. There was no significant difference in aortic root PaO2 attributable to ventilation. PCO2 was significantly lower, and pH was significantly higher in the ventilated group. Based on these results, the authors believe that it is a safe practice to withhold ventilation under the above-stated conditions.
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U2 - 10.1016/0888-6296(89)90112-9
DO - 10.1016/0888-6296(89)90112-9
M3 - Article
C2 - 2520654
AN - SCOPUS:0024361899
VL - 3
SP - 301
EP - 304
JO - Journal of Cardiothoracic and Vascular Anesthesia
JF - Journal of Cardiothoracic and Vascular Anesthesia
SN - 1053-0770
IS - 3
ER -