LIQUID ASSISTED VENTILATION - AN ALTERNATIVE VENTILATORY STRATEGY FORACUTE MECONIUM ASPIRATION INJURY

Evidence of surfactant inactivation by meconium has led to the use of exogenous surfactant therapy in the management of meconium aspiration syndrome (MAS). Liquid assisted ventilation has been shown to improve the cardiopulmonary function in lungs with high surface tension. We co mpared exogenous surfactant therapy with liquid assisted ventilation i n the management of experimental acute meconium aspiration injury. Thi rty-two newborn lambs were ventilated at peak inspiratory pressures of 13-16 cm H2O, positive end expiratory pressure of 3-4 cm H2O, fractio nal inspired oxygen concentration (F1O2) of 1.0, and a respiratory fre quency range between 30 and 35 breaths/min. Baseline arterial blood ga ses, pulmonary function, and arterial blood pressure measurements were taken. All lambs were given 2-3 ml/kg of an unfiltered 25% meconium s olution. Lambs were then randomized into either gas-ventilated meconiu m control, or one of three treatment groups: 1) surfactant; 2) partial liquid ventilation (PLV); or 3) total liquid ventilation (TLV) for 4 hours after meconium injury. All treated groups demonstrated a signifi cant increase in arterial oxygenation (P < 0.05); surfactant and PLV-t reated lambs demonstrated significantly decreased arterial PCO2 (P < 0 .05). Compliance in all groups increased compared with injury values; compliance of the TLV group increased more than in all other treatment groups (P < 0.05). In addition, lung histology of the TLV group demon strated clear, intact alveolar epithelium and homogeneously expanded a lveoli, while no such improvement was evident in the other groups. The se data suggest roles for both exogenous surfactant therapy and liquid assisted ventilation techniques in the management of MAS. (C) 1996 Wi ley-Liss, Inc.