Increased inspiratory effort has been demonstrated during obstructive sleep apnea events.^1,2 We have previously demonstrated that transcutaneous diaphragmatic EMG(tcEMG), a measure of inspiratory effort, was increased during inspiratory muscle loading in awake OSA patients who had not used NCPAP.³ This study compares inspiratory effort during inspiratory loading of non-OSA patients to OSA patients treated with CPAP for an average of 25 months.

METHOD

Transcutaneous diaphragmatic EMG electrodes were applied to each patient and the tcEMG signal was monitored while each patient was awake and at rest breathing through a Threshold muscle loading device set at pressures of -7, -14, and -21 cm H2O. The changes in in tcDEMG signals of five non-OSA patients (RDI’S <5) were compared to five OSA patient (RDI’S >30) and ten OSA patients who had used CPAP. (average 25 months).

RESULTS

TcDEMG signals showed a greater increase with inspiratory muscle loading in the OSA patient and the OSA patient treated with CPAP, than in non-OSA patients. (p < 0.05)

CONCLUSION

The inspiratory effort, as measured by tcDEMG, during inspiratory loads is significantly greater in OSA patients and OSA treated patients treated with CPAP than in non-OSA patients. T-tests showed that tcDEMG signals at each of the inspiratory loaded pressures were different for non-OSA vs. OSA and non-OSA vs. CPAP patients at the P<.05 level. Our findings suggest that the propensity for airway closer in OSA subjects persists despite NCPAP.

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1 Votteri et al, Sleep Research, Transcutaneous Diaphragm Moitoring to Assess the Efficacy of Nasal CPAP, 19:383, 1990

2 Gothe, Bruce, Goldman; Sleep and Breathing; Respiratory Muscle Function, New York; Marcel Dekker, Inc., 1984 p250

3 Votteri et al, Sleep Research; A Diagnostic Method for Detecting Sleep Apnea in the Awake Subject, 21:272, 1992