Chest
Clinical InvestigationsSLEEP AND BREATHINGAbbreviated Method for Assessing Upper Airway Function in Obstructive Sleep Apnea
Section snippets
Patient Selection
Ten patients with OSA were recruited for this study from the Sleep Disorders Unit at the University Hospital Antwerp, Belgium. Theywere considered eligible if the respiratory disturbance index (RDI)during nonrapid eye movement (NREM) sleep was > 10 episodes/h. Patients with any concurrent medical illnesses except hypertension wereexcluded. The Local Review Board of the Antwerp University Hospitalapproved the protocol for which all patients gave informed consent.
Study Design
Each patient underwent baseline
Patient Characteristics
Anthropometric, pulmonary function, and PSG data at baseline are presented in Table 1. Patients included in this study were middle-aged obese men who had PSGevidence of severe OSA (NREM RDI, 61.7 ± 7.0 episodes/h). No patientwas hypoxemic (Pao2 < 65 mm Hg) orhypercapnic (Paco2 > 45 mm Hg)during wakefulness. Moreover, no significant change in BMI or neckcircumference occurred between baseline and experimental PSG. BMI was32.0 ± 5.6 kg/m2 and 32.0 ± 5.8kg/m2, respectively).
Analysis of Vimax Responses to StepDecreases in Pn
Step decreases in Pn
Discussion
In this study, we developed an abbreviated, standardized methodfor characterizing upper airway function during sleep by examiningpressure-flow relationships for the upper airway in patients with OSA. These relationships were constructed from breaths obtained afterlowering Pn abruptly from a relatively high holding pressure level. When several breaths were evaluated after step reductions in Pn, wefound that the level of Vimax fell to a relativelylow level within the first three breaths and
ACKNOWLEDGMENT
The authors thank M. Willemen for his technicalassistance and L. Allan for his help in analyzing the data andpreparing the Figures for this article.
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Supported by HL 503781, HL 37379, and the Fund of Scientific ResearchFlanders (FWO), Belgium.