Active glottal closure during central apneas limits oxygen desaturation in premature lambs.
Our laboratory previously reported that active glottal closure was present in 90% of spontaneous central apneas in premature lambs while maintaining a high-apneic lung volume (Renolleau S, Letourneau P, Niyonsenga T, and Praud JP. Am J Respir Crit Care Med 159: 1396-1404, 1999.) The present study aimed at testing whether this mechanism limits postapnea oxygen desaturation. Four premature lambs were instrumented for recording states of alertness, thyroarytenoid muscle and diaphragm electromyographic (EMG) activity, nasal airflow, lung volume changes, and pulse oximetry. One thousand four hundred fifty-two spontaneous central apneas (isolated or during periodic breathing) were analyzed in nonsedated lambs. Apneas, with high lung volume maintained by active glottal closure, were compared with apneas, with a tracheostomy opened at apnea onset. Oxygen desaturation slopes were lower when high-apneic lung volume was actively maintained during both wakefulness and quiet sleep. Furthermore, oxygen desaturation slopes were lower after isolated apneas with continuous thyroarytenoid EMG during wakefulness, compared with apneas with noncontinuous thyroarytenoid EMG (= glottis opened shortly after apnea onset). These results highlight the importance of maintaining high-alveolar oxygen stores during central apneas by active glottal closure to limit desaturation in newborns.
Reix
Philippe
P
Departments of Pediatrics, Pulmonary Research Unit, University of Sherbrooke, Québec, Canada J1H 5N4.
Arsenault
Julie
J
Dome
Valerie
V
Fortier
Pierre-Hugues
PH
Lafond
Joelle Rouillard
JR
Moreau-Bussiere
Francois
F
Dorion
Dominique
D
Praud
Jean-Paul
JP
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001049:Apnea / Q000503:physiopathology*; D003964:Diaphragm / Q000503:physiopathology; D004562:Electrocardiography; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D005931:Glottis / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D011247:Pregnancy; D015656:Respiratory Mechanics / Q000502:physiology; D012756:Sheep; D012890:Sleep / Q000502:physiology; D014139:Tracheostomy; D014851:Wakefulness / Q000502:physiology