Respiratory effort during obstructive sleep apnea: role of age and sleep state.
OBJECTIVE
To evaluate the patients' individual characteristics predictive of the degree of respiratory effort developed during obstructive sleep apneas (OSAs).


METHODS
Prospective consecutive sample, collection of clinical and polysomnographic data.


METHODS
University teaching hospital.


METHODS
One hundred sixteen consecutive OSA patients with clinical symptoms of OSA and more than 20 apneas per hour of sleep.


METHODS
Anthropomorphic data, daytime blood gas values, and polysomnographic data. From esophageal pressure measurements during sleep, three indexes of respiratory effort during OSAs were derived: the maximal end-apneic esophageal pressure swing (PesMax), the increase in esophageal pressure swing (deltaPes) during the apnea, and its ratio to apnea duration (RPes).


RESULTS
The indexes of respiratory effort were significantly lower in rapid eye movement (REM) than in non-REM sleep (PesMax: 50.9+/-2.5 vs 39.6+/-1.9 cm H2O, p<0.001; deltaPes: 30.9+/-1.7 vs 23.4+/-1.4 cm H2O, p<0.001; RPes: 1.05+/-0.05 vs 0.53+/-0.03 cm H2O/s, p<0.001); therefore, a separate analysis was conducted in non-REM and in REM sleep. Indexes were also significantly lower in subgroups of older as compared to younger patients (PesMax: 55.6+/-3.5 vs 40.0+/-2.2 cm H2O, p<0.001; deltaPes: 34.2+/-2.3 vs 24.1+/-1.6 cm H2O, p=0.001; RPes: 1.21+/-0.08 vs 0.8+/-0.05 cm H2O/s, p<0.001). The three indexes were closely correlated with each other and only PesMax correlation data are reported. In non-REM sleep, age was the most important single independent correlate of PesMax (r=-0.37, p=0.000). In REM sleep, the apnea-related hypoxemia, apnea duration, and age were the main contributors to the variance of PesMax.


CONCLUSIONS
Respiratory effort in response to upper airway occlusion in OSA patients is lower in REM than in non-REM sleep and decreases with increasing age.
Krieger
J
J
Sleep Disorders Unit, University Hospital, Strasbourg, France. jean.krieger@neuro-ulp.u-strasbg.fr
Sforza
E
E
Boudewijns
A
A
Zamagni
M
M
Petiau
C
C
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000097:blood; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005544:Forecasting; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D011312:Pressure; D011446:Prospective Studies; D012044:Regression Analysis; D012119:Respiration / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology; D013997:Time Factors
D002245:Carbon Dioxide; D010100:Oxygen