J Korean Med Sci.  2001 Feb;16(1):51-56. 10.3346/jkms.2001.16.1.51.

Changes in dead space/tidal volume ratio and pulmonary mechanics after surfactant replacement therapy in respiratory distress syndrome of the newborn infants

• Chung EH
• Ko SY
• Kim IY
• Chang YS
• Park WS

• KMID: 1066494
• DOI: http://doi.org/10.3346/jkms.2001.16.1.51

Abstract

This study was performed to elucidate the mechanism of improved oxygenation after surfactant replacement therapy in respiratory distress syndrome (RDS) of the newborn infants. In 26 newborns with RDS, end tidal-CO2 tension (PetCO2), arterial blood gas analysis and pulmonary function tests were measured at baseline, 30 min, 2 hr and 6 hr after surfactant administration. The changes in dead space/tidal volume ratio (VD/VT ratio=(PaCO2-PetCO2)/PaCO2), oxygenation index and arterial-alveolar partial pressure difference for oxygen ((A-a)DO2) were elucidated and correlated with pulmonary mechanics. Oxygenation index and (A-a)DO2 improved, and VD/VT ratio decreased progressively after surfactant administration, becoming significantly different from the baseline at 30 min and thereafter with administration of surfactant. Pulmonary mechanics did not change significantly during the observation period. VD/VT ratio showed close correlation with OI and (A-a)DO2, but not with pulmonary mechanics. These results suggest that decreased physiologic dead space resulting from the recruitment of atelectatic alveoli rather than improvement in pulmonary mechanics is primarily responsible for the improved oxygenation after surfactant therapy in the RDS of newborn.

Keyword

Respiratory Distress Syndrome; Respiratory Dead Space; Tidal Volume; Pulmonary Surfactants; Respiratory Mechanics

MeSH Terms

Airway Resistance
Human
Infant, Newborn
Lung/physiopathology*
Lung Compliance
Pulmonary Gas Exchange
Pulmonary Surfactants/therapeutic use*
Respiratory Dead Space*
Respiratory Distress Syndrome/physiopathology
Respiratory Distress Syndrome/drug therapy*
Tidal Volume*