Metabolic activity of the lung during cardiopulmonary bypass

Metabolic functions of the lung were examined in sixty patients undergoing coronary artery bypass surgery employing a method to separate right and left heart flow during surgery. Six study groups were employed to investigate the activity of normal serum electrolytes, minerals, enzymes and vasoactive prostanoids as they pass through the pulmonary vasculature. Various sample sites were employed to represent isolated segments of the vascular tree: pump (systemic) and right atrium (myocardium), aortic (bronchial flow). LDH, Ca++, phosphate and SGOT were documented to vary with passage through the pulmonary circulation while alkaline phosphatase, bilirubin, creatinine, urate, cholesterol, albumin and BUN remained essentially unchanged. Bronchial flow was calculated and directly related to temperature and pump flow with an average range of 15 ml/min +/- 6 ml/min. The stress of surgery produced elevated PGE2 in bronchial flow and urine that caused reproducible hypotension when rapidly reinfused into the patient. PGE2 production, though decreased with Indomethacin block, could be rapidly reversed with the stress of surgery.