Background: Term and preterm infants are at risk of developing apnea after receiving general anesthesia. The risk of apnea after sedation with chloral hydrate (CH) in this population is unknown. In this study, we aimed to describe the clinical course of infants younger than 1 year who received CH for magnetic resonance imaging (MRI), with regard to the efficacy of CH sedation, the need for additional sedative drugs, and the incidence of oxyhemoglobin desaturation or need for oxygen supplementation. We aimed to determine the relationship between these factors to chronological age in term infants and gestational and postconceptional age (PCA) in preterm infants (<37 weeks' gestation).
Methods: This was a retrospective cohort study of 1394 infants undergoing MRI examination with CH sedation. Infants with an endotracheal tube, tracheostomy tube, or congenital heart disease were excluded. Patient charts were examined in detail to determine independent risk factors and dependent outcome variables up to 24 hours after MRI. Univariate and multivariate analyses were performed to determine risk factors for outcome variables.
Results: Postprocedure oxyhemoglobin desaturation was more likely in inpatients (P < 0.001) and was associated with a lower body weight (3.9 +/- 2.1 kg vs 6.6 +/- 3.0 kg; P < 0.001), history of apnea (33.3% vs 9.9%; P = 0.001), higher ASA physical status (P = 0.002), and younger chronological age (58.7 +/- 82.8 days vs 152 +/- 105.9 days; P < 0.0001). When the preterm group was analyzed separately, the risk of postprocedure oxyhemoglobin desaturation was directly correlated with younger chronological age (56.0 +/- 41.5 days vs 150.6 +/- 107.1 days; P = 0.012) and younger PCA (39.5 +/- 4.1 weeks vs 54.4 +/- 15.2 weeks; P = 0.005), but not gestational age. Preterm infants had more postprocedure bradycardia than term infants (P = 0.005). Postprocedural oxyhemoglobin desaturation was not seen in preterm infants older than 48 weeks' PCA. Because of the relatively small percentage of cases (8 of 262) of postprocedural oxyhemoglobin desaturation in preterm infants, we were not able to definitively determine the difference in incidence between preterm and term infants. Additional doses of CH or supplementation with midazolam did not increase the incidence of complications.
Conclusions: The occurrence of postprocedural oxyhemoglobin desaturation was directly correlated with younger chronological age in term infants and younger PCA in preterm infants. Term infants who required extended oxygen supplementation were inpatients and had significant comorbidities.