TY - JOUR
T1 - Nasal and oral flow-volume loops in normal subjects and patients with obstructive sleep apnea
AU - Shepard, J. W.
AU - Burger, C. D.
PY - 1990
Y1 - 1990
N2 - Because flow-volume loops (FVLs) are clinically useful in evaluating upper airway (UA) obstruction and the fact that patency of the nasopharyngeal ventilatory pathway is important to the prevention of obstructive sleep apnea (OSA), the present study examined the role of nasal compared with oral FVLs in evaluating patients with OSA. Fourteen obese male patients 56 ± 3 yr of age with a mean apnea plus hypopnea index (AHI) of 51 ± 9/h were studied along with 14 nonobese, healthy, age- and sex-matched control subjects whose mean AHI was 6 ± 1/h. Nasal and oral FVLs obtained in the normal subjects indicated the nose behaved like a variable resistor, with flow limitation during inspiration but not during expiration. In the patient group, flow limitation was observed during expiration as well as inspiration indicating nondistensibility of the nasopharyngeal ventilatory pathway in the patients compared to the control subjects. A change in body position from upright to supine in the OSA group was associated with small reductions in expiratory but not inspiratory flow rates. The area under the nasal supine flow-volume loop (FVLA(NaSup)) was found to be highly correlated with awake resting Pa(O2) (r = 0.80) and Pa(CO2) (r = -0.83) in the patient group. In addition, multiple linear regression analysis revealed that Pa(O2) and the area under the nasal FVLs independently contributed to the prediction of AHI with a multiple R of 0.89. These results suggests that limitations to ventilation via the nasopharynx may significantly influence both gas exchange and the frequency of sleep-disordered breathing in patients with OSA. Because obese control subjects were not studied, the role of obesity independent of OSA in the development of abnormal nasal FVLs could not be determined.
AB - Because flow-volume loops (FVLs) are clinically useful in evaluating upper airway (UA) obstruction and the fact that patency of the nasopharyngeal ventilatory pathway is important to the prevention of obstructive sleep apnea (OSA), the present study examined the role of nasal compared with oral FVLs in evaluating patients with OSA. Fourteen obese male patients 56 ± 3 yr of age with a mean apnea plus hypopnea index (AHI) of 51 ± 9/h were studied along with 14 nonobese, healthy, age- and sex-matched control subjects whose mean AHI was 6 ± 1/h. Nasal and oral FVLs obtained in the normal subjects indicated the nose behaved like a variable resistor, with flow limitation during inspiration but not during expiration. In the patient group, flow limitation was observed during expiration as well as inspiration indicating nondistensibility of the nasopharyngeal ventilatory pathway in the patients compared to the control subjects. A change in body position from upright to supine in the OSA group was associated with small reductions in expiratory but not inspiratory flow rates. The area under the nasal supine flow-volume loop (FVLA(NaSup)) was found to be highly correlated with awake resting Pa(O2) (r = 0.80) and Pa(CO2) (r = -0.83) in the patient group. In addition, multiple linear regression analysis revealed that Pa(O2) and the area under the nasal FVLs independently contributed to the prediction of AHI with a multiple R of 0.89. These results suggests that limitations to ventilation via the nasopharynx may significantly influence both gas exchange and the frequency of sleep-disordered breathing in patients with OSA. Because obese control subjects were not studied, the role of obesity independent of OSA in the development of abnormal nasal FVLs could not be determined.
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U2 - 10.1164/ajrccm/142.6_Pt_1.1288
DO - 10.1164/ajrccm/142.6_Pt_1.1288
M3 - Article
C2 - 2252246
AN - SCOPUS:0025605474
SN - 0003-0805
VL - 142
SP - 1288
EP - 1293
JO - American Review of Respiratory Disease
JF - American Review of Respiratory Disease
IS - 6
ER -