RESUSCITATION OF THE NEWBORN INFANT

Abstract

IN ORDER to initiate respiration, the newborn infant must be able to overcome a resistance to expansion of the lungs which is often as high as 30 cm. H2O. The lungs will remain atelectatic until an adequate respiratory effort is made. The infant may make one or two feeble attempts at respiration but then cease breathing, perhaps because these efforts are of insufficient magnitude to overcome the atelectasis. In such instances the force of the respiratory movements may be increased by external stimuli while intubation and removal of secretions from the tracheo-bronchial tree may reduce the resistance to expansion so that the infant's efforts are adequate. However, certain infants appear to require additional assistance in order to overcome this resistance. If the presence of initial atelectasis is a significant factor in preventing the onset of respiration, it would seem reasonable to make a strong effort to alleviate this condition. Since the lungs offer a resistance to expansion of about 30 cm. H2O, any resuscitating device should exert pressures great enough to overcome this resistance. However, Wilson, Torrey and Johnson found that while a pressure of 24.4 cm. H2O did not cause expansion of the lung of the stillborn infant, it was great enough to cause gross pulmonary damage. Others have warned of alveolar rupture at even lower pressures and for this reason present-day resuscitators operate at low pressures. Day et al. have recently pointed out the importance of time-pressure relationships in overcoming atelectasis and demonstrated that a pressure of 40 cm. H2O effectively overcame atelectasis of animal foetal lungs without producing lung damage if the pressure was applied for less than 0.25 seconds. It was therefore of interest to develop a resuscitator operating on a "timed-pressure" principle and to study the results obtained when it was used in the resuscitation of newborn infants with markedly depressed respiration.