Comparison of microsphere and intraoperative quantitation of bronchial blood flow

Although significant variation in bronchial blood flow (BBF) has been reported, precise quantitation is difficult because of the small sized vessels and variable anatomy. Ventricular balance is critical to the function of the total artificial heart (TAH), and variation in BBF can alter this balance in the bovine model. Bronchial blood flow was measured in 12 calves by two methods: six by the radioactive labeled microsphere technique (MBBF), and six intraoperatively (IBBF) during cardiopulmonary bypass (CPB). In the MBBF group, BBF ranged from 1.9 ml/kg to 16.0 ml/kg, whereas IBBF varied from 2.6 ml/kg to 10 ml/kg (NS). Cardiac output (CO) was significantly higher (p less than 0.0005) in the MBBF group. Bronchial blood flow in both groups was highly variable. The higher flow in the MBBF group may be attributed to the arteriovenous shunting of microspheres, whereas lower flow in the IBBF group may be secondary to physiologic changes during CPB. This technique, described to measure IBBF, can estimate large variations in the natural right to left shunt that contributes to imbalance in the TAH.