Current knowledge suggests that laryngeal chemoreflexes (LCR) are involved in the occurrence of certain neonatal
apneas/
bradycardias, especially in the preterm newborn. While
caffeine and/or
nasal continuous positive airway pressure (nCPAP) are the most frequent options used for treating
apneas in preterm newborns, their effects on LCR-related
apneas/
bradycardias are virtually unknown. The aim of the present study was to test the hypothesis that
caffeine and/or nCPAP decreases LCR-related cardiorespiratory inhibition in a preterm ovine model. Seven preterm lambs were born vaginally on gestational day 133 (normal gestation: 147 days) after
intramuscular injections of
betamethasone and
mifepristone. Five days after birth, a chronic surgical instrumentation was performed to record states of alertness, electrocardiogram, systemic arterial pressure, and electromyographic activity of a laryngeal constrictor muscle, as well as to insert a transcutaneous supraglottal
catheter. LCR were induced in quiet sleep under four conditions: 1) control (without
caffeine or nCPAP); 2) nCPAP (5 cmH2O, without
caffeine); 3)
caffeine (10 mg/kg infused intravenously for 30 min, without nCPAP); and 4) nCPAP +
caffeine. Our results showed that nCPAP consistently blunted LCR-related cardiorespiratory inhibition vs. control condition, contrary to
caffeine whose overall effect was nonsignificant. In addition, nCPAP condition was characterized by a more consistent and rapid arousal after HCl injection. No significant differences were observed between all tested conditions with regard to swallowing and
cough. It is concluded that nCPAP should be further assessed for its usefulness in treating neonatal
apneas linked to LCR.