Studies of Respiratory Physiology in the Newborn Infant. I. Observations on Normal Premature and Full-Term Infants 1

Abstract

This report describes an investigation of the respiratory physiology of normal premature and full-term newborn infants. As in previous studies on normals (1-3), minute volumes, rates and tidal volumes have been measured. Additional measurements of CO2 production, plasma CO2 partial pressure, and intraesophageal pressure differences have allowed calculations of effective alveolar ventilation, functional dead space and estimates of the work of respiration. Since certain adaptations were necessary for the study of this age group, the techniques are reported in detail. The data from normal infants are the subject of this report; comparable data for newborns with respiratory distress are reported in a second paper (4). MATERIALThe 63 infants studied by one or more techniques were delivered at the Boston Lying-in Hospital and were considered normal in all respects except that 17 were premature by weight. They ranged from 36 to 42 weeks gestational age and from 1.82 to 4.25 Kg. birth weight. Delivery was spontaneous vertex or low forceps except in five infants delivered by Caesarian section (three because of previous section, one for marginal placental separation, and one for postmaturity), and four by breech extraction. Their ages at the time of observation ranged from three hours to seven days (Tables I-III). Most of those under two days had not been fed prior to the studies. METHODSThe minute volume (V),4 rate (f), and tidal volume (VT), were measured in 35 infants by means of a 65-liter

Ventilatory Studies in Healthy Infants

“…In newborn infants, COOK et al [8] found a mean intraesophageal pressure difference of 5 cm H,O, a value substantially less than that found in the present study. In adults, MEAD [25] found a range of 3 to 8 cm H,O, which was also lower than that in the present series.…”

Lung Function and Acid‐base Balance in the Newborn Infant

“…The small size and the lack of cooperation of the subject to be studied make pulmonary function investigation in the newborn period difficult and limit its possibilities. The present series of studies as well as those of others [Cook et al, 1955;Stahlman, 1957;Nelson et al, 1962;Strang and McGrath, 1962;Prod'hom et al, 1964;and others), however, have demonstrated that suitable methods can be developed or adapted permitting inves tigation of the main mechanisms in respira tory function even in the youngest age group.…”

Pulmonary Ventilation and Diffusion in the Human Newborn Infant1

“…Because of the marked differences in the size of the subjects, the volumes of gases to be measured, and the problems of resistance to expiration and dead space which arise when such equipment is used in small infants, these techniques have not previously been applied to the study of infants. Indirect methods, using a body plethysmograph (1)(2)(3)(4)(5)(6)(7)(8)(9), have allowed the estimation of some of the elements of ventilation, but cannot be applied to measurements of diffusion or distribution of inspired air.…”