Abstract 1806 Historical Perspectives Poster Symposium, Saturday, 5/1

In 1950, Allan P. Bloxsom (1901-1991), A pediatrician at the St. Joseph Hospital in Houston, introduced his positive pressure oxygen-air lock (AL) for the delivery room resuscitation of the asphyxiated newborn. The infant's entire body was placed into a cylindrical steel chamber which was tightly sealed and infused with warmed humidified 60% oxygen. The positive pressure within the AL was cycled between 1 and 3 lbs. per in2 at 1 minute intervals to simulate the intrauterine pressures during the second stage of labor. Bloxsom developed the AL device in response to his hypothesis that the contractions of labor help to "condition" the infant for extrauterine survival. Parmalee said that the AL "certainly locks the infant up, safe from meddlesome and unintelligent treatment". When clear plastic versions of the AL became commercially available, it received widespread use in delivery rooms and newborn nurseries throughout the US. In 1953, Apgar and Kreiselman produced apnea in adult dogs using pentobarbital and a muscle relaxant, and found that the AL device was unsuccessful for the oxygenation and ventilation of the animals. In 1954, Townsend in Rochester NY reported on his experience with the AL in 150 premature infants. He concluded that the AL should be "more accurately referred to as an oxygenator" and that "the truly apneic infant cannot be maintained in an acyanotic state by the AL". The AL was finally subjected to the scrutiny of a randomized controlled clinical trial which was published in 1956. Reichelderfer and Nitowsky at Johns Hopkins randomized 171 infants to receive care in the AL or in an Isolette. Routine resuscitation, including positive pressure ventilation was administered, as needed, to both study groups before placement into the AL or Isolette. They did not find any differences in the outcomes of the two study groups. By the mid-1950's, new information linking oxygen therapy and retrolental fibroplasia led to a rapid decline in the use of the AL, even before the publication of the randomized trial.