Respiratory Muscle Strength as an Indicator of the Severity of the Apnea-Hypopnea Index: Stepping Towards the Distinction Between Sleep Apnea and Breath Holding

Vasileios T Stavrou; Kyriaki Astara; Eleni Karetsi; Zoe Daniil; Konstantinos I Gourgoulianis

doi:10.7759/cureus.14015

Respiratory Muscle Strength as an Indicator of the Severity of the Apnea-Hypopnea Index: Stepping Towards the Distinction Between Sleep Apnea and Breath Holding

Cureus. 2021 Mar 21;13(3):e14015. doi: 10.7759/cureus.14015.

Authors

Vasileios T Stavrou¹, Kyriaki Astara¹, Eleni Karetsi¹, Zoe Daniil¹, Konstantinos I Gourgoulianis¹

Affiliation

¹ Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC.

Abstract

Background and objective The aim of this study was to investigate whether the maximum inspiratory and expiratory pressure are correlated with the apnea-hypopnea index (AHI) in patients with obstructive sleep apnea syndrome (OSAS). Methods Fifty-two patients with OSAS were divided into two groups (AHI, events/hours: <30, n=28, versus ≥30, n=24). For each patient, anthropometric characteristics, spirometry parameters, maximum inspiratory (MIP) and expiratory pressure (MEP), and cardiopulmonary function (CPF) parameters (oxygen uptake at rest (VO₂), carbon dioxide output (VCO₂), heart rate (HR), minute ventilation (V_E), tidal volume at inspiratory (TVin) and expiratory (TVex), breath frequency (f _β), end-tidal carbon dioxide pressure (P_ETCO₂), end-tidal oxygen pressure (P_ETO₂), and mean arterial pressure (MAP)) in sitting position for three minutes were recorded. The independent t-test was used to measure the differences between groups (events/hours <30 versus ≥30) and Pearson correlation analysis was used for statistical comparison between parameters. Results Results showed differences between groups (AHI, events/h ≥30 versus <30) in MIP (102.0±18.3 versus 91.1±12.1 % of predicted, p=0.013) and CPF parameters TVin (0.8±0.2 versus 0.7±0.1, L, p=0.047), P_ETCO₂ (34.6±4.2 versus 31.4±3.7, mmHg, p=0.007), and MAP (88.4±6.5 versus 82.9±6.2, mmHg, p=0.003). Pearson correlation analysis between respiratory muscle strength (MIP and MEP) and polysomnography (PSG) parameters, MIP is related to AHI (r=.332, p=0.016) and desaturation index (r=.439, p=0.001), as well as MEP to percent of REM sleep stage (r=-.564, p<0.001). Conclusion The data from the present study support that maximal inspiratory pressure relates to the severity of AHI and intermittent breath-holding during sleep increases the inspiratory muscle strength.

Keywords: cardiopulmonary function; male; respiratory muscle strength; sleep apnea.