The ventilatory response to carbon dioxide in high risk infants

Abstract

Purpose: To examine the ventilatory response to inspired carbon dioxide in infants considered to be at risk for sudden infant death syndrome or apnea. Design: Clinical data measurement. Setting: Infant apnea evaluation program of a university division of neonatology. Patients: Fifty nine infants were full term characterized by the following diagnoses; siblings of infants who had died from sudden infant death syndrome (SIDS) ( n = 7), apparent life threatening event (ALTE) ( n = 24), apnea/cyanosis in the newborn nursery ( n = 21), and controls [7]. Sixty-nine infants were preterm and consisted of patients suffering from idiopathic apnea ( n = 61), and bronchopulmonary dysplasia ( n = 8). Measurements: The ventilatory response to carbon dioxide was measured with a computerized waveform analyzer. Main results: Among full term infants no significant differences in the ventilatory slope in response to CO 2 was seen. The range of mean slope was 19.4 ± 7.6 in siblings of SIDS and 36 ± 17 in control infants. Greater number of sibling of SIDS had slopes less than 20 ml/kg/min/mmHg in comparison to control infants. Sibling of SIDS had less increase in minute ventilation and inspiratory flow in response to CO 2 administration in comparison to control infants. Preterm infants had similar slopes with a mean of 33 ml/kg/min/mmHg in infants with idiopathic apnea and 28 ml/kg/min/mmHg in infants with bronchopulmonary dysplasia. Conclusions: The large intragroup variability in the ventilatory response to inspired CO 2, confirming previously reported data, compromises the benefit of this test. Thus, ventilatory response to CO 2 administration is not useful in unselected patients at risk of SIDS or apnea.