Issue |
J Extra Corpor Technol
Volume 21, 1989
Proceedings of AmSECT’s 27th International Conference
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Page(s) | 96 - 101 | |
DOI | https://doi.org/10.1051/ject/198921S096 | |
Published online | 24 August 2023 |
Original Article
The Use of the Classical Shunt Equation in the Evaluation of Coronary Artery Hypoxemia During Cardiopulmonary Bypass
Providence Medical Center, Portland, OR
* Address correspondence to: Charles F. Jerabek, Department of Surgery, Providence Medical Center, 4805 N. E. Glisan, Portland, OR 97213
With the decreasing usage of left heart venting in routine cardiac surgery, there is a possibility of coronary artery hypoxemia impairing myocardial recovery after the removal of the aortic cross clamp. This study was undertaken to determine whether coronary artery hypoxemia was present in the period following clamp removal and if the degree of hypoxemia could be predicted. Fifteen patients were studied with blood gas samples being drawn from the aortic root (as near to the coronary ostia as possible), oxygenator inflow line, radial artery line and oxygenator venous return line at a rewarming temperature of at least 34°c. Relative coronary artery hypoxemia was present in nine patients. No pre-operative tests predicted the patients at risk for developing this condition. A modification of the classical shunt equation proved to be the most accurate test (R=.86) to predict coronary artery pO2 levels. Proposed solutions to the problem of coronary artery hypoxemia include left heart venting when the shunt is >5% (a value of 10% is projected to be acceptable when oxygenator pO2 exceeds 250), leaving the patient hooked to the anesthesia machine with a sweep gas FIO2 of >80% and the use of PEEP or low frequency ventilation during the rewarming period.
Key words: Oxygenator / ventilation / pulmonary circulation
© 1989 AMSECT
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