Effect of Sleep State on the Laryngeal Chemoreflex in Neonatal Piglets

The laryngeal chemoreflex (LCR) is a brain stem-mediated response that is a potential mechanism for sudden infant death syndrome. The vast majority of sudden infant death occurs during sleep, yet it remains to be established whether there is a particular sleep state that makes an infant animal more susceptible to apneic events via the LCR. The purpose of this study was to investigate the LCR during different sleep states in the neonatal piglet. In this study, continuous physiologic monitoring and electroencephalographic, electro-oculographic, and electromyographic techniques were utilized to study neonatal piglets during a hypnotic induced sleep model. Propofol drip anesthetic was utilized to provide an anesthetic state and was titrated for dose-dependent sedation. The LCR was initiated in 11 animals during quiet sleep, rapid eye movement sleep, and the anesthetic state. Baseline respiratory and cardiovascular responses were measured. Durations of apnea were recorded and compared. This study found that despite known physiologic differences in respiratory control during different sleep states as compared to the anesthetic state, there appears to be no increased risk of profound apnea in one state versus another in piglets 19 to 28 days old.