BRONCHOALVEOLAR LAVAGE WITH KL4-SURFACTANT IN MODELS OF MECONIUM ASPIRATION SYNDROME

As a model of the meconium aspiration syndrome (MAS) of human infants, adult rabbits and newborn rhesus monkeys received intratracheal insti llation of human meconium to induce pulmonary injury. Injured rabbits were ventilated with 100% O-2 and divided into four treatment groups, receiving: I) bronchoalveolar lavages (BAL) with dilute KL4-Surfactant ; 2) lavages with equal volumes of sterile saline; 3) a single intratr acheal bolus of KL4-Surfactant, 100 mg/kg; and 4) no treatment. The un treated rabbits developed atelectasis, a fall in pressure-volume level s and in partial pressure of O-2 in arterial blood (Pao(3) from approx imately 500 to <100 mmHg, and severe pulmonary inflammation between 3 and 5 h after instillation of meconium. Rabbits treated by BAL with di lute KL4-Surfactant showed rapid and sustained recovery of Pao(2) to a pproximately 300 mm Hg within minutes, a return toward normal pressure -volume levels, and diminished inflammation, Rabbits receiving BAL wit h saline failed to show recovery, and rabbits treated with a bolus of surfactant intratracheally exhibited a transient response by 1-2 h aft er treatment, but then returned to the initial atelectatic state. Newb orn rhesus monkeys, after receiving human meconium intratracheally bef ore the first breath, developed severe loss of pulmonary function. Tre atment of these monkeys 1-5 h after birth with BAL with dilute KL4-Sur factant produced clearing of chest radiographs and a rapid improvement in pulmonary function with ratios of partial pressure of O-2 in arter ial blood to the fraction of O-2 in the inspired air rising into the n ormal range where they remained through the 20-h period of study. The studies indicate that pulmonary function in two models of severe mecon ium injury respond rapidly to BAL with dilute KL4-Surfactant.