Partial pressure of carbon dioxide in extremely low birth weight infants supported by nasal prongs continuous positive airway pressure.

Objective: Traditionally, delivery room management of extremely low birth weight (ELBW) infants consisted of immediate intubation and mechanical ventilation. There have been recent reports of success using nasal prongs continuous positive airway pressure (NCPAP) in this population. Data on the partial pressure of carbon dioxide (PCO(2)) in spontaneously breathing ELBW infants is very limited. The objective of this study was to determine the trend of the average PCO(2) in the spontaneously breathing ELBW infants, while on NCPAP, during the first week of life and to determine whether a brief period of mechanical ventilation affects the PCO(2) levels after extubation.

Methods: This is a retrospective cohort study of infants who had birth weights <1000 g and were admitted to the neonatal intensive care unit at our institution. These ELBW infants were divided into groups on the basis of whether they were never intubated (group 1) or were intubated for <48 hours (group 2). Average daily PCO(2) levels while on NCPAP were compared between the 2 groups. Minimum and maximum PCO(2) levels were also compared with a third group of infants (group 3), who were intubated for >48 hours and treated mainly with mechanical ventilation during the first week of life.

Results: Sixty-two ELBW infants were included in this study: 24 infants in group 1, 19 infants in group 2, and 19 infants in group 3. There was no significant difference between the average PCO(2) levels of group 1 and group 2 during the first week of life. The daily PCO(2) level during the first week of life for infants who were breathing spontaneously on NCPAP had a mean value of 39.73 +/- 1.78 mm Hg. There was no difference between the daily average minimum PCO(2) levels among the 3 groups. Group 3, however, had significantly higher maximum PCO(2) levels compared with the first 2 groups during days 2 through 7 of life.

Conclusions: Daily average PCO(2) levels in the spontaneously breathing ELBW infants during the first week of life remains at approximately 40 mm Hg. These levels seem to be unaffected by an initial brief period of mechanical ventilation. Infants who are treated with longer periods of mechanical ventilation have higher daily maximum PCO(2) levels during the first week of life. Additional studies are required to detect neurodevelopmental outcomes of these 3 groups.