Twitch Mouth Pressure and Disease Severity in Subjects With COPD

C. Ju, W. Liu, R.-c. Chen
2013 Respiratory care  
Patients with chronic obstructive pulmonary disease (COPD) have impaired respiratory muscle strength. Twitch mouth pressure (TwPM) in response to magnetic stimulation of the cervical nerve has been suggested to clinically reflect inspiratory muscle strength. However, studies on TwPM values and their relationship with disease severity are limited. Thus, we tested the TwPM values of COPD patients and investigated the relationship of these values with disease severity. Methods: We recruited 75
more » ... We recruited 75 COPD patients and 63 age-matched controls. All participants were tested for TwPM, sniff nasal pressure (SNIP), and maximum static inspiratory mouth pressure (PImax); the BODE (body mass index, airflow obstruction, dyspnea, exercise capacity) index was evaluated for overall severity assessment and the six-minute walk distance (6-MWD) was used to determine the exercise capacity of COPD patients. Results : COPD patients had markedly lower TwPM values compared with the controls [(10.00±2.17) vs. (13.66±2.20) cmH 2 O for males, (8.83±0.89) vs. (11.81±1.98) cmH 2 O for female, each with p < 0.001]. The TwPM values decreased with increasing COPD severity, and similar trends were observed in the SNIP and PImax values. Regression correlation analysis showed that TwPM values were significantly correlated inversely with the BODE index (R = 0.65; p < 0.001) but positively correlated with 6-MWD (R = 0.59; p < 0.001) in the COPD group; the SNIP values of COPD patients were also correlated inversely with their BODE index (R = 0.49; p < 0.001) but positively correlated with their 6-MWD (R = 0.33; p < 0.005). Conclusion: TwPM values are 26.8% lower in male COPD patients and 25.3% lower in female COPD patients compared with the controls. The TwPM values of COPD patients decrease with increasing disease severity. TwPM was better correlated with the BODE index and exercise capacity than SNIP and PImax, which suggest that TwPM more accurately reflects the overall severity and burden of COPD.
doi:10.4187/respcare.02553 pmid:24129337 fatcat:4xag7bexobadxemm5u7waayyuu