Vol. 94, Issue 1, 31-37, January 2003
Discriminative power of phrenic twitch-induced dynamic
response for diagnosis of sleep apnea during wakefulness
Eric
Verin1,2,3,
Thomas
Similowski2,4,
Antonio
Teixeira2,4,5, and
Frédéric
Sériès1,2
1 Centre de recherche, Hôpital Laval, Institut
universitaire de cardiologie et de pneumologie de
l'Université Laval, Québec, Canada G1V 4G5;
2 UPRES EA 2397, Université Paris VI Pierre et
Marie Curie, Paris; 3 Service de Physiologie, Centre
Hospitalier Universitaire de Rouen, Rouen 76051; and
4 Laboratoire de Physiopathologie Respiratoire,
Service de Pneumologie and 5 Service de Médecine
Interne, Groupe Hospitalier Pitié-Salpêtrière,
Assistance Publique 
Hôpitaux de Paris, Paris 75651, France
The diagnosis
of the obstructive sleep apnea syndrome relies on polysomnography.
Bilateral anterior magnetic phrenic stimulation (BAMPS) mimics the
dissociation between upper airway (UA) muscles and diaphragm commands
that leads to UA closure during sleep. We evaluated BAMPS as a mean to
identify obstructive sleep apnea syndrome patients through the
characterization of the UA dynamics in 28 consecutive awake patients
(18 apneic and 10 nonapneic). Driving pressure (Pd) and instantaneous
flow (
) were recorded in response to BAMPS to determine
the point of flow limitation (Imax) and of minimal
flow (Imin) and the flow-pressure
relationship [I = (k1 × Pd) + (k2 × Pd2)]. Imax,
Imin, UA resistance at
Imin, and the coefficient of the
flow-pressure relationship (k1) were
correlated with apnea-hypopnea index (respectively, R = 
0.735, P < 0.0001; R = 0.584,
P = 0.001; R = 0.474, P = 0.01; and R = 0.567, P < 0.01).
Body mass index was also correlated with apnea-hypopnea index
(R = 0.500, P < 0.01). Apneic patients
had a lower Imax (Imax = 678 ± 386 vs. 1,247 ± 271 ml/s; P < 0.001), a lower Imin (Imin = 460 ± 313 vs. 822 ± 393 ml/s; P < 0.05)
and a lower k1 (k1 = 162 ± 67 vs. 272 ± 112 ml · cmH2O · s
1;
P < 0.01) than nonapneic ones. Using a
classification and regression tree approach, we found that a
Imax of <803 ml/s (n = 12) selected only apneic patients. When Imax of >803
ml/s (n = 16), a k1 of >266.7
ml · cmH2O · s1
identified only nonapneic patients (n = 5). In 11 cases, Imax > 803 ml/s and
k1 < 266.7 ml · cmH2O · s1.
These included five nonapneic and six apneic patients. We conclude that
UA dynamic properties studied with BAMPS during wakefulness significantly differ between nonapneic and apneic patients.
sleep apnea syndrome; phrenic nerve; stimulation; magnetic; upper
airway
