Pulmonary function in the newborn infant: the alveolar-arterial oxygen gradient

Nelson, Nicholas M.; Prod’hom, L. S.; Cherry, Ruth B.; Lipsitz, Philip J.; Smith, Clement A.

doi:10.1152/jappl.1963.18.3.534

Cited by 89 publications

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“…This study confirms the observations of others [13,15] in demonstrating gas trapping in the lungs of premature infants. Trapped gas is present from birth and persists for a variable period of time, in some cases as long as 40 days.…”

Section: Discussionsupporting

confidence: 93%

“…Other considerations suggesting that mixing occurred in the time period covered by the test are: (1) Nitrogen washout analysis indicates that in most cases the lungs are washed out in 30 sec. (2) FRC values in this study are in close agreement with the results of others [5,13] one of whom used a rebreathing method [5]. (3) Another indication of the validity of the method was the constancy of the helium FRC with time as it was approached by the TGV.…”

Section: Evaluation Of the Helium Rebreathing Methodssupporting

confidence: 91%

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Pulmonary Gas Trapping in Premature Infants

Krauss

Auld

1971

Pediatr Res

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ExtractMeasurements of thoracic gas volume and functional residual capacity were performed serially from birth on 26 premature infants to determine the presence and time course of gas trapping. Nitrogen washouts were carried out on 16 of these infants and urinary-alveolar nitrogen gradients (uAD Nj ) were measured in 7. The infants were divided into two groups, those above and those below 1750 g birth weight.Trapped gas was documented in both groups, but in the smaller infants the condition persisted for a longer time. The mean thoracic gas volume (TGV) in infants over 1750 g birth weight was 2.0 ±0.7 ml/cm at birth, with a mean functional residual capacity (FRC) of 1.3 ± 0.4 ml/cm; by day 9, the TGV and FRC were 1.5 ± 0.3 and 1.2 ± 0.2 ml/cm, respectively. Infants under 1750 g birth weight had a mean TGV of 1.7 ± 0.2 ml/cm at birth with an FRC of 0.9 ± 0.2 ml/cm; by week 2 of life, mean TGV and FRC were 0.9 ± 0.2 and 0.8 ± 0.2 ml/cm, respectively. When gas trapping was present, nitrogen washouts and uAD N2 indicated that the lung was a single well ventilated space with no evidence of an abnormal distribution of ventilation. This indicated that ventilation of the trapped areas was so small that it could not be measured. The possibility that gas trapping is related to the presence of lung fluid and very compliant airways is considered. Speculation

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Section: Discussionsupporting

confidence: 93%

Section: Evaluation Of the Helium Rebreathing Methodssupporting

confidence: 91%

Pulmonary Gas Trapping in Premature Infants

Krauss

Auld

1971

Pediatr Res

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“…There is good qualitative evidence that bidirectional shunts occur in all these sites [12,17,251. During the first 24-48 hours of life, the pulmonary artery pressure is close to systemic levels and falls steadily during this time [5]; nevertheless, R + L shunting through the ductus has been demonstrated in normal newborn babies at this age [4,16,191.…”

Section: Introductionmentioning

confidence: 99%

Ductus Arteriosus Shunts in the Respiratory Distress Syndrome

Roberton

Dahlenburg

1969

Pediatr Res

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ExtractThe arterial blood gas tensions in the right radial artery and the lower abdominal aorta were compared in 2 1 infants suffering from respiratory distress syndrome. Simultaneous sampling was carried out using a radial artery catheter inserted by a cut-down technique and an umbilical arterial catheter inserted into the abdominal aorta. One hundred thirty-nine simultaneous blood samples were analysed for paO,, pH, and pCO,. In no case was there any significant difference in p H and pCO, values in samples of blood drawn from the two sites. Differences in paO, were observed but owing to inherent errors in measurement, only differences of greater than 10 mm Hg were regarded as significant. In 27 out of the 139 determinations, paO, from the right radial artery exceeded that from the abdominal aorta by more than 10 mm Hg. The babies studied were divided into the following groups : Group 1, 6 babies with no significant paO, difference between the two sampling sites. Group 2(a), 6 babies with significantly higher oxygen tensions in blood drawn from the radial artery but only at aortic paO, levels of more than 140 mm Hg. I n this group there were no significant differences when the abdominal aorta paO, was less than 140 mm Hg. Group 2(b), 3 babies with slightly higher radial artery oxygen tensions only when they were being ventilated with a positive pressure respirator. Group 2(c), 6 babies with significantly higher paO, levels in the radial artery at arterial oxygen tensions of less than 100 mm Hg. I n two of these babies, the right radial paO, (and therefore presumably the retinal artery paO,) would have exceeded 160 mm Hg had the ambient oxygen concentration been raised sufficiently to produce an aorta paO, of 100 mm Hg and had the total shunt and the proportion passing through the ductus arteriosus remained constant. I n two of these babies, however, increasing ambient oxygen concentration decreased the total shunt and the proportion of the shunt passing through the ductus. In the remaining four babies in Group 2(c), the severity of the disease was such that it was impossible to raise the aorta paO, to 100 mm Hg.From these data it seems that most of the R -L shunt in respiratory distress syndrome must pass through the foramen ovale or the lungs. Only rarely does more than 15 % of the R -L shunt pass through the ductus arteriosus.The final quantitative differentiation between shunting in the lungs and through the foramen ovale is most likely to be made by dye dilution studies from peripheral vein or right atrial injections.

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“…Severe pulmonary hypertension can cause right-to-left shunting of blood across the foramen ovale and the ductus arteriosus. This shunting can exacerbate hypoxemia in premature infants (23,28). Walther et al.…”

mentioning

confidence: 99%

The Effects of Nitric Oxide Inhalation on the Pulmonary Circulation of Preterm Lambs

1995

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This study was designed to test the hypothesis that inhalation of nitric oxide by lambs delivered prematurely would result in increased systemic arterial blood oxygen tension and decreased pulmonary vascular resistance. Eleven premature fetal lambs were delivered by cesarean section at 126-127 d gestation. One hundred min after the onset of ventilation, nitric oxide gas was added to the lambs' breathing mixture. The animals were exposed in random order to 5 pprn for 10 min, 20 pprn for 10 min, and 20 pprn for 20 min. Each treatment period was preceded by and followed by a 10-min washout period. When compared with the washout (control) periods, all three treatment periods resulted in an improvement in both the systemic arterial blood oxygen tension and the physiologic intrapulmonary shunt. Inhalation of nitric oxide also resulted in a selective decrease in pulmonary arterial blood pressure. Comparisons between the different treatment groups revealed a further improvement in blood oxygenation and pulmonary hemodynamics when using the higher concentration of nitric oxide. Interestingly, the rise in arterial blood oxygenation continued after inhaling 20 pprn nitric oxide for more than 10 min. (Pediatr Res 37: [35][36][37][38][39][40] 1995) Abbreviations QsIQt, physiologic intrapulmonary shunt PAP, mean pulmonary arterial pressure ppm, parts per million RDS, respiratory distress syndrome SAP, mean systemic arterial pressure LAP, left atrial pressure RAP, right atrial pressure Qp, pulmonary blood flow PVR, pulmonary vascular resistance Pao,, arterial oxygen partial pressure Nitric oxide, an inorganic gas formed by combustion processes, has been recognized for many years as an industrial pollutant. In fact, cigarette smoke contains nitric oxide gas in concentrations up to 1000 pprn (1). In both dogs (2, 3) and humans (4-6), inhalation of concentrations of more than 15 000 pprn rapidly causes a fatal condition involving severe alveolar edema, methemoglobinemia, and hypoxemia. Ironically, inhalation of concentrations less than 100 pprn has been used in an attempt to facilitate the management of several cardiopulmonary diseases such as persistent pulmonary hypertension of the newborn (7,8), primary pulmonary hypertension (9, lo), and adult RDS (11).Treatment of pulmonary hypertension with i.v. administered vasodilator agents has been limited because of the inability to localize the effects of these drugs to the pulmonary circulation. Nitric oxide gas seems to be an ideal drug to obviate this problem. Experience in animals (12-16) and humans (9,17) Received March 18, 1994; accepted June 5, 1994. Supported by grants from the American Heart Association, Florida Affiliate (AHA Awards 93CRFl6, 92Fl2, and 91GIAn16), and the National Institute of Health Grant HL10834.suggests that inhaled nitric oxide can cause a decrease in PVR without causing significant systemic hypotension. The mechanisms of this selective pulmonary vasodilation are not entirely understood; however, the short half-life of nitric oxide (18,19) and its rapi...

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Pulmonary function in the newborn infant: the alveolar-arterial oxygen gradient

Cited by 89 publications

References 0 publications

Pulmonary Gas Trapping in Premature Infants

Pulmonary Gas Trapping in Premature Infants

Ductus Arteriosus Shunts in the Respiratory Distress Syndrome

The Effects of Nitric Oxide Inhalation on the Pulmonary Circulation of Preterm Lambs

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