Changes in blood gas tensions following administration of amine buffer THAM to infants with respiratory distress syndrome.

Abstract

A number of workers have shown that the prognosis in respiratory distress syndrome (RDS) is more closely related to the arterial oxygen tension than to acid-base disturbance, and depends to a large extent on the degree of shunting of venous blood past the gas-exchanging portions of lung, i.e. on the extent to which the arterial Po2 responds to an increase in the concentration of oxygen breathed (Boston, Geller, and Smith, 1966; Gupta, 1966; Moss, Emmanouilides, Retorri, Higashino, and Adams, 1965). These findings are to some extent in conflict with claims that the prognosis is improved by correction of the secondary acid-base distur- bance by infusion of glucose/bicarbonate solutions (Usher, 1959; Hutchison, Kerr, Douglas, Inall, and Crosbie, 1964). It occurred to us that these two points of view might be reconciled if it could be shown that correction of pH leads to improvement in oxygenation and diminution of shunting, a consequence that might be predicted in the new- born from the dependence of pulmonary perfusion on pH and blood gas tensions (Cassin, Dawes, Mott, Ross, and Strang, 1964) as well as on adequate cardiac function. THAM rather than bicarbonate was used because of its greater alkalinity and its ability to lower the PaCo2 (Nahas, 1959; Holmdahl, Nahas, Hassam, and Verosky, 1961) as well as to raise the pH. It was decided to measure Po2 levels in arterial blood before and after administration of THAM and to see whether any improvement in PaO2 so achieved would be sustained. During the course of the study the work of Chu, Clements, Cotton, Klaus, Sweet, Thomas, and Tooley (1965) in Singapore became known to us, and reinforced our belief that pulmonary hypoperfusion might be a