Compact apparatus for measurement of ventilatory response to carbon dioxide in newborns and infants.

We developed a rebreathing system for measuring response to carbon dioxide (CO2) of newborns and infants for use at the bedside. The system based on Read's method is small, easy to operate, and includes a computer-controlled gas switching sequence, computerized calculation, and display functions. We measured the CO2 response in 11 infants with or without apnea, who were born at 26-33 weeks gestation and were 12 to 215 days old at the time of the study. Our results suggest that the presence of apnea in premature infants may correspond to a low CO2 response. The method was convenient for clinical use because it allowed an investigator to carry out bedside tests in only a few minutes. With our system we were able to assess respiratory center function in newborns and infants.