We compared the validity of the arterial/alveolar oxygen tension ratio (Pao₂/PAO₂), the alveolar-arterial oxygen tension difference [P(A-a)o₂], and the calculated shunt fraction (Qs/Qt) as indices of the severity of respiratory distress syndrome (RDS) in 6 infants up to 3 hours old, in 1 infant to the age of 72 hours, and in I infant to the age of 108 hours. We found that, in infants with acute RDS in whom hypoxemia is related to shunt, the Pao₂/PAO₂ was more useful than the P(A-a)o₂ in following the course of the severity of RDS and in comparing the disease state among infants. In addition, the Pao₂/PAO₂ may be useful in predicting the Pao₂ that would result from a given decrease in the fraction of inspired oxygen (Fro₂) in such infants. (Cohen A, Taeusch HW Jr, Stanton C. Usefulness of the Arterial/Alveolar Oxygen Tension Ratio in the Care of Infants with Respiratory Distress Syndrome. Respir Care 1983:28:169-173
NelsonNM, Prud'homLS, CherryRB, LipsitzPJ, SmithCA. Pulmonary function in the newborn infant: The alveolar/arterial oxygen gradient. J Appl Physiol1963;18:534–538.
2.
BenatarSR, HewlettAM, NunnJF. The use of iso shunt lines for the control of oxygen therapy. Br J Anaesth1973;45:711–718.
3.
GilbertR, AuchinclossJH, KuppingerM, ThomasVM. Stability of the arterial/alveolar oxygen partial pressure ratio. Crit Care Med1979;7:267–272.
4.
GottusoMA, WilliamsML, OskiFA. The role of exchange transfusions in the management of low birthweight infants with and without severe respiratory distress syndrome. J Pediatr1978;89:279–285.
5.
BorosSJ. Variations in inspiratory:expiratory ratio and airway pressure wave form during mechanical ventilation: The significance of mean airway pressure. J Pediatr1979;94:114–117.
6.
ClohertyJP, StarkAR, eds. Manual of neonatal care. Boston: Little, Brown & Co, 1980.
7.
Users manual available from the Center for the Analysis of Health Practices, Harvard School of Public Health, Boston MA 02115.
8.
GlantzS.Primer of biostatistics. New York: McGraw Hill Book Co, 1981.
9.
AveryME, FletcherBD. The lung and its disorders in the newborn. 4th ed. Philadelphia: WB Saunders, 1981:68.
10.
HolmanWL, KraussAN, AuldPAM. Serial determinations of oxygen profiles in infants with respiratory distress syndrome. Arch Dis Child1978;53:136–140.
11.
NelsonNM, Prud'homLS, CherryRB, LipsitzPJ, SmithCA. Pulmonary function in the newborn infant. V: Trapped gas in the normal infant lung. J Clin Invest1963;42:1850–1857.
12.
NelsonNM, Prud'homLS, CherryRB, LipsitzPJ, SmithCA. Pulmonary function in newborn infants. II: Perfusion estimation by analysis of the alveolar/arterial carbon dioxide difference. Pediatrics1962;30:975–977.
13.
GersonyWM, DucGV, DellRB, SinclairJC. Oxygen method for the calculation of right-to-left shunt: A new application in the presence of right-to-left shunting through the ductus arteriosus. Cardiovasc Res1972;6:423–438.
