title: Effects of caffeine and/or nasal CPAP treatment on laryngeal chemoreflexes in preterm lambs.
abstract: 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.
authors.affiliation: Neonatal Respiratory Research Unit, Departments of Pediatrics and Physiology, Université de Sherbrooke, Quebec, Canada J1H 5N4.
authors.forename: Nadia
authors.initials: N
authors.lastname: Boudaa
authors.forename: Nathalie
authors.initials: N
authors.lastname: Samson
authors.forename: Vincent
authors.initials: V
authors.lastname: Carrière
authors.forename: Pamela Samanta
authors.initials: PS
authors.lastname: Germim
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Pasquier
authors.forename: Aida
authors.initials: A
authors.lastname: Bairam
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Praud
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001049:Apnea / Q000503:physiopathology; D062186:Arterial Pressure / Q000187:drug effects / Q000502:physiology; D001919:Bradycardia / Q000503:physiopathology; D002110:Caffeine / Q000494:pharmacology*; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D007830:Larynx / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D012018:Reflex / Q000187:drug effects* / Q000502:physiology*; D012756:Sheep / Q000196:embryology / Q000502:physiology*
chemical_list: D002110:Caffeine