SLEEP - Performance Characteristics of Upper Airway Critical Collapsing Pressure Measurements during Sleep

VOLUME 34, ISSUE 04

UPPER AIRWAY CRITICAL COLLAPSING PRESSURE DURING SLEEP
Performance Characteristics of Upper Airway Critical Collapsing Pressure Measurements during Sleep

Jason P. Kirkness, PhD¹; Leigh A. Peterson, MHS¹; Samuel B. Squier, BS¹; Brian M. McGinley, MD¹; Hartmut Schneider, MD, PhD¹; Adrian Meyer²; Alan R. Schwartz, MD¹; Philip L. Smith, MD¹; Susheel P. Patil, MD, PhD¹

¹Johns Hopkins Sleep Disorders Center, Johns Hopkins School of Medicine, Baltimore, MD; ²Hals-Nasen-Ohrenklinik, Kantonsspital St.Gallen, St Gallen, Switzerland

Table of Contents

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Objective:

The critical pressure (P_CRIT), a measurement of upper airway collapsibility, is a determinant of the severity of upper airway obstruction during sleep. We examined the performance characteristics of the passive and active P_CRIT by examining both within-night and between-night variability in the measurements.

Methods:

We studied 54 sleep apnea patients (39 men, 15 women) and 34 normal subjects (20 men, 14 women) on either 1 or 2 nights during sleep. The P_CRIT was measured during relative hypotonia (“passive” state) or during periods of sustained upper airway obstruction used to recruit upper airway neuromuscular responses (“active” state) within- and between-nights. In a subgroup of 10 normal subjects, we performed repeated measurements during hypnotic-induced sleep. Bland-Altman analyses were used to determine the within-night and between-night reliability of the P_CRIT measurements.

Results:

There were no significant within-night or between-night differences for the mean passive P_CRIT. The active P_CRIT was ∼1 cm H₂O more collapsible on the second night than on the first night. The limits of agreement, which bound the passive and active P_CRIT, was ∼ ± 3 cm H₂O and was reduced to ∼ ± 1 cm H₂O for the passive P_CRIT with hypnotic-induced sleep.

Conclusion:

Passive and active P_CRIT measurements are reasonably reliable within and between nights. An approximately 3 cm H₂O change in passive or active P_CRIT appears to represent the minimally significant change in P_CRIT necessary to assess the effect of an intervention (e.g., positional therapy, surgical interventions, oral appliance effects, and pharmacotherapy) on upper airway mechanical loads or neuromuscular responses.

Citation:

Kirkness JP; Peterson LA; Squier SB; McGinley BM; Schneider H; Meyer A; Schwartz AR; Smith PL; Patil SP. Performance characteristics of upper airway critical collapsing pressure measurements during sleep. SLEEP 2011;34(4):459-467.