Vulnerability of the neonatal respiratory control system to sustained hypoxia

Abstract

The developing respiratory neural control system is particularly vulnerable to environmental challenges including changes in oxygenation. In the current study, we investigated how neonatal hypoxia exposure during selected periods of development modifies the ventilatory response to acute hypoxia (hypoxic ventilatory response, HVR). Using whole body plethysmography, the magnitude of the acute HVR was measured in neonatal rats following exposure to sustained hypoxia (SH, 11% O2) during selected periods of development. Neonatal rats were exposed to SH between postnatal (P) age P1–5, P10–15, or P20–25. The magnitude of the acute HVR in rats exposed to SH between P1–5 (40.4±8.7% of baseline) and P20–25 (55.5±9.5%) was similar to age‐matched normoxic rats (35.9±3.6% and 49.6±6.0%, respectively). In contrast, the HVR was absent (4.4±11.1%) in rats exposed to SH between P10–15, revealing a vulnerable period of development in which the respiratory control system mediating the HVR is disturbed by SH. These data may be important to our understanding of the importance of avoiding prolonged periods of reduced O2 saturation in the intensive care of preterm infants during uniquely sensitive periods of development. Funding: Dept. of Pediatrics, Rainbow Babies and Children's Hospital.