RESPIRATORY PATTERNS IN NEWBORN INFANTS AS DETERMINED BY AIRFLOW AND PNEUMOGRAPHIC STUDIES AND THEIR POSSIBLE RELATIONSHIP TO A DEFICIENT VAGAL MECHANISM

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Abstract
Pneumographic tracings of the movements of the upper chest, lower chest and abdomen have been recorded individually and simultaneously with the velocity of air flow by means of electronic equipment in 70 newborn infants. A total of 114 recordings were made on infants from zero to 49 days of age and with birth weights of 1000 gm. or more. Most infants during the first 24 hours after birth had a respiratory pattern in which the inspiratory and expiratory movements of the upper chest, lower chest and abdomen were parallel and tended to be synchronous. In a few infants at birth and in most older infants this respiratory pattern was modified. The modification consisted in the lower chest tending to move in a direction opposite to that of the abdomen and upper chest. The theory has been advanced that diaphragmatic breathing, which is so characterisitc of older infants, is not completely established at birth except in a few infants who perhaps are more mature. In the more mature infant, contraction of the diaphragm probably exerts a pull on the lower chest, causing its indrawing during inspiration. It has been suggested that inability to develop adequate diaphragmatic contractions may be an important factor in the many neonatal deaths that occur in the first few days of life. It has been pointed out that the newborn infant may have a poorly developed vagal mechanism and that this may be one of the factors causing diaphragmatic activity to be inadequate. Observations on three infants who died during the first 48 hours of life are reported which tend to support the theory that vagal deficiency is a possible cause of inadequate diaphragmatic activity, pulmonary hyaline membranes and neonatal death.