Objective: To compare respiratory nocturnal
polysomnography (NPSG) characteristics between matched cohorts of upper
airway resistance syndrome (UARS) and obstructive sleep apnea syndrome
Methods: All patients received
13-channel NPSG, including esophageal pressure (Pes) manometry. By
definition, OSAS patients had an apnea-hypopnea index (AHI, number of
apneas/hypopneas per hour total sleep time) ≥ 15, and UARS patients
had an AHI < 5. Respiratory effort-related arousal (RERA) was defined
as the absence of apnea/hypopnea with ≥ 10 s duration of progressive
negative Pes, culminating in an arousal or microarousal. UARS patients,
by definition, had ≥ 15 RERAs per hour. Fifteen consecutively
diagnosed UARS patients were matched with OSAS patients on the basis of
body mass index (BMI) and gender.
disturbance index (sum of the AHI and RERA per hour) was the same for
both cohorts: UARS, 36 ± 4; OSAS, 42 ± 6 (p = 0.34). There were
no differences between cohorts for mean inspiratory Pes nadirs for each
30-s epoch of sleep compared for each sleep stage over an entire night.
For randomly selected breaths from supine stage 2 sleep, the mean
inspiratory Pes nadir was the same for the cohorts: UARS, −16.6 ± 2
cm H2O; OSAS, −16.1 ± 3 cm H2O
(p = 0.30). Differences between cohorts for each parameter fell
within respective 95% confidence intervals.
Conclusion: With the exception of AHI, respiratory NPSG
parameters were the same for UARS and OSAS patients when BMI and gender
were controlled for.
Abbreviations: AHI = apnea/hypopnea index;
BMI = body mass index; CI = confidence interval; NPSG = nocturnal
polysomnography; OSAS = obstructive sleep apnea syndrome;
Pes = esophageal pressure; RDI = respiratory disturbance index;
RERA = respiratory effort-related arousal; UARS = upper airway