Objective: To determine the sensitivity and specificity
of quantitative respiratory inductive plethysmography (RIP) compared
with the “gold standard,” nocturnal esophageal pressure (Pes)
measurement, in the diagnosis of upper airway resistance syndrome
(UARS) in adults.
Methods: Fourteen consecutive
patients without obstructive sleep apnea and suspected of having UARS
underwent simultaneous measurement of Pes with a catheter and standard
nocturnal polysomnography along with RIP. UARS events (RERAs,
respiratory effort-related arousals) were identified by observing
crescendo changes in Pes with a Pes nadir ≤ −12 cm H2O,
followed by an arousal or microarousal. UARS was defined as ≥ 10
RERAs per hour. For each patient, the ratio of peak inspiratory flow to
mean inspiratory flow (PIFMF) measured by RIP was performed during
quiet wakefulness and with 40 randomly selected breaths in the supine
position for two conditions: stage 2 sleep, immediately prior to
arousals in any sleep stage. The mean PIFMF (wake-sleep) was calculated
for each condition.
Results: The sensitivities and
specificities, respectively, of RIP to distinguish UARS patients from
non-UARS patients are from stage 2 sleep (67%, 80%), immediately
prior to arousals (100%, 100%). For breaths occurring immediately
prior to arousals, the mean PIFMF (wake-sleep) is ≥ 0.13 for UARS
patients and < 0.13 for non-UARS patients.
Conclusion: The PIFMF measured by RIP allows for the most
accurate identification of UARS patients when breaths are selected for
analysis immediately prior to arousals.
Abbreviations: AHI = apnea-hypopnea index;
BMI = body mass index; NPSG = nocturnal polysomnography;
OSA = obstructive sleep apnea; Pes = esophageal pressure;
PIFMF = peak inspiratory flow to mean flow ratio;
RERA = respiratory effort-related arousal; RIP = respiratory
inductive plethysmography; UARS = upper airway resistance syndrome