Association of Respiratory Mechanic Instability and Respiratory Parameters among Adults with Obstructive Sleep Apnea

Abstract

Objectives Respiratory mechanic instability (RMI) is derived from analysis of paradoxical thoracoabdominal movements during airway obstruction. This study aimed to evaluate RMI parameters in obstructive sleep apnea (OSA) and the correlation between RMI parameters and other parameters in polysomnography. Study Design Retrospective review. Setting A university hospital. Methods A retrospective chart review was performed, and data from 189 adult patients who underwent an in-laboratory sleep study and were seen in our clinic during the past 8 months. The RMI parameters were measured from thoracoabdominal bands during polysomnography. Results Subjects were divided into 2 groups: control (n = 67, apnea-hypopnea index [AHI] <5) and OSA (n = 122, AHI ≥5). The OSA group was divided into 3 subgroups according to AHI: mild, 5 ≤ AHI < 15; moderate, 15 ≤ AHI < 30; severe, AHI ≥30. As AHI increased, all RMI parameters showed a significant rising pattern and difference between control and subgroups. Arousal index, lowest oxygen saturation, and oxygen desaturation index ≥3% were significantly correlated with all RMI parameters. Based on cutoff values, areas under the curves of the RMI index for predicting mild, moderate, and severe OSA were >0.85. Conclusion All RMI parameters were well related to respiratory parameters of polysomnography, such as arousal index, lowest oxygen saturation, and oxygen desaturation index ≥3%. The areas under the curves of all RMI parameters for predicting OSA and subgroups showed significant diagnostic performance. These parameters may be useful to identify OSA cases from control.

The Usefulness of Respiratory Mechanic Instability in Evaluating the Effect of Continuous Positive Airway Pressure for Obstructive Sleep Apnea

“…All pre-CPAP titration RMI parameters were close to the levels in the moderate to severe OSA group, and all post-CPAP titration RMI parameters were decreased to those in the normal or mild OSA group in our previous study. 7 These findings support that each RMI parameter decreased in proportion to the decline of AHI. During inspiration, both the thoracic and abdominal cavities concurrently increase both volume and circumference.…”

“…Therefore, we concluded that the degree of paradoxical movements may reflect the severity of apnea and hypopnea effectively. 7 Considering the above findings, RMI parameters could evaluate the effectiveness of OSA treatment such as CPAP sufficiently.…”

“…8,9 In previous study, all RMI parameters are closely related to oxidative stress, similarly with ODI3 among OSA patients. 7 Additionally, using a cutoff values of all RMI parameters, the areas under the curve of these parameters for predicting OSA ranged from 0.68 to 0.7. Our outcomes would be consistent with previous results.…”

“…The results suggested that all RMI parameters during sleep had a relatively good correlation with respiratory parameters of polysomnography. 7 In particular, RMI parameters such as events and index were highly correlated with AHI. Our previous study confirmed the possibility that RMI is useful to estimate obstructive respiratory events in the diagnosis of OSA.…”