Effects of ventilation and nonventilation on pulmonary venous blood gases and markers of lung hypoxia in humans undergoing total cardiopulmonary bypass.
OBJECTIVE
To assess the effects of lung oxygenation and ventilation vs. lung collapse on pulmonary markers of lung hypoxia.


METHODS
A prospective, nonrandomized, nonblinded comparative study.


METHODS
University department of anesthesiology and cardiothoracic surgery.


METHODS
Twelve adult patients undergoing coronary bypass grafting requiring total cardiopulmonary bypass.


METHODS
Single lung ventilation during total cardiopulmonary bypass (tidal volume, 150 mL; respiratory rate, 6 breaths/min; inspiratory oxygen fraction, 0.5) while the contralateral lung was allowed to collapse completely without oxygenation.


RESULTS
At the beginning and at the end of total cardiopulmonary bypass (duration, 59-65 mins), blood was aspirated from the right and left pulmonary veins and the radial artery for measurement of blood gases and concentrations of endothelin-1, big-endothelin, thromboxane B2, lactate, and lactate dehydrogenase. Nonventilation during total cardiopulmonary bypass compared with ventilation resulted in lower pulmonary venous P(O2) values (57+/-15 torr [7.6+/-2.0 kPa] vs. 103+/-23 torr [13.7+/-3.1 kPa]) and higher thromboxane B2 concentrations (488+/-95 pg/mL vs. 434+/-92 pg/mL). The concentrations of endothelin-1, big-endothelin, lactate, and lactate dehydrogenase in the pulmonary veins did not differ significantly between nonventilated and ventilated lungs.


CONCLUSIONS
Development of pulmonary tissue hypoxia during 1 hr of nonventilation and cardiopulmonary bypass with completely inhibited pulmonary arterial blood flow is unlikely, suggesting that enough oxygen is stored in or is provided to the collapsed lung. Thus, nonventilation during total cardiopulmonary bypass does not appear to contribute to postoperative respiratory dysfunction by causing pulmonary tissue hypoxia. These results, however, do not exclude that mechanical factors of ventilation might benefit the lung during cardiopulmonary bypass.
Loer
S A
SA
Department of Anesthesiology, Heinrich-Heine-University, Düsseldorf, Germany.
Kalweit
G
G
Tarnow
J
J
D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000097:blood*; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003422:Critical Care; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000628:therapy*; D008168:Lung / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011667:Pulmonary Veins; D012121:Respiration, Artificial
D002245:Carbon Dioxide; D010100:Oxygen