Continuous endobronchial insufflation during internal mammary artery harvest

Endobronchial insufflation of oxygen offers possible advantages over conventional ventilation modes in some clinical situations in which nonmovement of the chest may be desirable; however, endobronchial insufflation of oxygen has yet to be used during thoracic surgery in humans. Furthermore, the physiologic mechanisms underlying gas exchange during endobronchial insufflation of oxygen are unclear. This study assessed endobronchial insufflation of oxygen at 45 L/min in 11 patients with an open chest during internal mammary artery harvest. Cardiorespiratory function was measured at baseline during conventional mechanical ventilation and at 5-min intervals during the study period of 20-30 min. In all patients, clinically acceptable gas exchange was achieved, although PaCO2 increased from 32 +/- 3.2 to 44 +/- 7.5 mm Hg (mean +/- SD) at 5 min, but thereafter was unchanged (P greater than 0.1). Cardiac output, vascular pressures, and heart rate were unchanged, although pHa decreased. Surgical access for internal mammary artery harvesting was improved. No mucosal damage or complications occurred. During endobronchial insufflation of oxygen, efficacy of gas exchange and body weight were not correlated, but both subject height and age were correlated with high PaO2 and low PaCO2. We conclude that (a) endobronchial insufflation of oxygen can be used in patients with an open chest; (b) the efficacy of endobronchial insufflation of oxygen is probably improved by increased lung size and by collateral ventilation; and (c) cardiogenic gas mixing contributes little to gas exchange during endobronchial insufflation of oxygen.