Il. Mortimore et Nj. Douglas, PALATAL MUSCLE EMG RESPONSE TO NEGATIVE-PRESSURE IN AWAKE SLEEP APNEIC AND CONTROL SUBJECTS, American journal of respiratory and critical care medicine, 156(3), 1997, pp. 867-873
Citations number
35
Categorie Soggetti
Emergency Medicine & Critical Care","Respiratory System
The sleep apnea/hypopnea syndrome (SAHS) affects 1-4% of the middle-ag
ed population and is caused by repeated occlusion of the upper airway
mainly at the retropalatal level. It is unclear why SAHS patients obst
ruct their upper airways during sleep while others do not. We hypothes
ized that upper airway dilator muscle function may be impaired in SAHS
patients and that chronic CPAP therapy may enhance upper airway funct
ion. We, therefore, examined the effects of upper airway negative pres
sure on reflex palatal muscle activity in 16 normal nonsnoring awake m
ale subjects and 16 awake SAHS patients using electromyography. The ap
plication of negative upper airway pressure (0 to -12.5 cm H2O) caused
increases in levator palatini (LP, p < 0.001) and palatoglossus (PG,
p < 0.001) activity, 100 msec after pressure stimulus in normal subjec
ts. Application of upper airway negative pressure in SAHS patients cau
sed an increase in LP activity (p < 0.05) but not in PG activity. Refl
ex electromyographic response to negative pressure was reduced in SAHS
patients compared to normal subjects for both muscles (p < 0.001). Wh
en the seven thinnest SAHS patients were compared with seven normal su
bjects matched for BMI and age, the SAHS patients still demonstrated i
mpaired responses to negative pressure for both muscles (p < 0.001). A
further eight SAHS patients were studied either while concurrently ta
king nightly CPAP therapy and also off CPAP (at least 3 nights). Chron
ic nightly CPAP therapy improved the reflex response of both LP (p < 0
.001) and PG (p = 0.003) to nasal negative pressure application. Thus,
untreated SAHS patients have impaired electromyographic responses to
negative upper airway pressure suggesting impaired defence of the uppe
r airway, which is improved by nightly CPAP therapy.