Abstract
The American Academy of Pediatrics and until recently the Canadian Paediatric Society recommend preterm infants undergo an Infant Car Seat Challenge test prior to discharge to rule out systemic oxygen desaturation when placed at a 45-degree angle in a car seat. Near-infrared spectroscopy (NIRS) provides objective measurements of the impact of systemic oxygen (SO(2)) desaturation, bradycardia, or both on cerebral regional oxygen saturation (rSO(2)). OBJECTIVE: To characterize baseline cerebral rSO(2) during a car seat trial in preterm infants ready for discharge. DESIGN/METHODS: A prospective observational study was performed in 20 infants (32 ± 5 weeks [mean] at a postmenstrual age 37 ± 6 weeks [mean]). Cerebral rSO(2) was continuously monitored by placing a NIRS transducer on head during Infant Car Seat Challenge (ICSC). Failure of an ICSC was defined as two SO(2) desaturation events below 85% for more than 20 seconds or one event below 80% for 10 seconds. RESULTS: The lowest SO(2) was 70% with a lowest NIRS recording of 68%. Three infants failed their ICSC, with the lowest rSO(2) in these three infants being 68%, above the lowest acceptable limit of 55%. Heart rate but not SO(2) appears to influence rSO(2) over the range of cerebral oxygenation seen. CONCLUSIONS: Baseline cerebral rSO(2) during ICSC oscillates between 68 and 90%. There were no episodes of significant cerebral oxygen desaturation in studied infants regardless of whether they passed or failed the ICSC. We postulate that former preterm infants are capable through cerebral autoregulation, of maintaining adequate cerebral blood flow in the presence of either systemic oxygen desaturation or bradycardia when they are otherwise ready for discharge.