I. Kianicka et Jp. Praud, INFLUENCE OF SLEEP STATES ON LARYNGEAL AND ABDOMINAL MUSCLE RESPONSE TO UPPER AIRWAY OCCLUSION IN LAMBS, Pediatric research, 41(6), 1997, pp. 862-871
This study was aimed at describing abdominal and laryngeal muscle resp
onses to upper airway occlusion (UAO) in early life and the effect of
sleep states on these responses. Twelve nonsedated, 9-26-d-old lambs w
ere studied. We simultaneously recorded 1) airflow (pneumotachograph face mask); 2) sleep states (electrocorticogram and electrooculogram)
; 3) abdominal muscle (external obliquus) electromyogram (EMG); and 4)
glottic constrictor (thyroarytenoid) and dilator (posterior cricoaryt
enoid and cricothyroid) muscle EMGs. The pneumotachograph was repeated
ly occluded for 15-30 s in wakefulness and natural sleep. We analyzed
90 occlusions during wakefulness (11 lambs), 28 during non-rapid eye m
ovement (nREM) sleep (six lambs), and 23 during rapid eye movement (RE
M) sleep (five lambs). A phasic expiratory external obliquus EMG was p
resent during baseline and progressively increased throughout UAO in w
akefulness and nREM sleep, but not in REM sleep. Phasic thyroarytenoid
EMG progressively increased during inspiratory efforts throughout UAO
in wakefulness and nREM sleep, paralleling the increase in glottic di
lator (posterior cricoarytenoid and cricothyroid) EMG. In contrast, gl
ottic muscle response to UAO in REM sleep was severely blunted or diso
rganized by frequent swallowing movements. We conclude that UAO trigge
rs complex and coordinated laryngeal and abdominal muscle responses du
ring wakefulness and nREM sleep in lambs; these responses are largely
absent, however, in REM sleep. These unique results, together with the
defective arousal response in REM sleep, suggest that vulnerability t
o airway occlusion could be increased during REM sleep in early life.
Possible implications for understanding severe postnatal apneas are di
scussed.