BACKGROUND: Evaluation of cough strength is clinically important, especially for patients with neuromuscular disorders and before extubation of mechanically ventilated patients. The pressure gradient between the airway and thoracoabdominal cavities during the cough expiratory phase generates cough flow and passive cephalic movement of the diaphragm. We hypothesized that passive diaphragmatic cephalic excursion, peak velocity, or both during cough expiration might predict cough peak flow (CPF). This physiologic study investigated associations of CPF with simultaneously measured ultrasonographic indices in healthy adults during the cough expiratory phase. METHODS: 56 healthy adults participated in this study. Right hemidiaphragm excursion and peak velocity were measured with ultrasonography during voluntary cough expiration with maximum effort. CPF was simultaneously measured for all coughs along with the ultrasonographic measurements. A linear regression model was used to determine whether ultrasonographic indices predicted CPF. RESULTS: Simple regression analysis showed significant associations between excursion and CPF in men and women (P < .001, beta coefficient 37.8, 95% CI 10.9-64.7, adjusted R 2 ‫؍‬ 0.195 for men; P < .001, beta coefficient 46.1, 95% CI 22.3-69.9, adjusted R 2 ‫؍‬ 0.386 for women). A multiple regression model adjusted for age, height, and sex showed a significant association between CPF and excursion (P < .001, adjusted beta coefficient 38.32, 95% CI 21.20-55.44, adjusted R 2 ‫؍‬ 0.643). Simple regression analysis showed a significant association between diaphragmatic peak velocity and CPF only in women (P ‫؍‬ .004, beta coefficient 5.07, 95% CI 1.81-8.33, adjusted R 2 ‫؍‬ 0.280 for women). CONCLUSIONS: Passive cephalic excursion of the diaphragm during the cough expiratory phase significantly predicted CPF with maximum cough effort in healthy adults. Future studies should investigate the relationship between CPF and excursion in persons with respiratory and neuromuscular disorders.

BACKGROUND: A cough peak flow (CPF) of < 60 L/min was associated with increased risk of extubation failure after a successful spontaneous breathing trial (SBT). Passive cephalic excursion of the diaphragm (PCED), measured by ultrasonography during cough expiration, was reported to predict CPF in healthy adults. We hypothesized that PCED, diaphragm peak velocity, or both during cough, as measured by ultrasonography, might predict CPF and extubation outcomes in mechanically ventilated patients. This study attempted to identify associations of diaphragm movement during cough, as assessed by ultrasonography with simultaneously measured CPF, and to determine predictive values of ultrasonographic indices for extubation outcomes after a successful SBT. METHODS: In the study, 252 mechanically ventilated subjects with a successful SBT were enrolled in a prospective cohort study. Right hemidiaphragm passive cephalic excursion and peak velocity were measured by ultrasonography during voluntary cough expiration with maximum effort. CPF was measured simultaneously by ultrasonography. RESULTS: A multiple regression model adjusted for age and sex showed a significant association between PCED and CPF (P < .001, adjusted b coefficient 11.4, 95% CI 8.88-14.0, adjusted R 2 5 0.287) and between diaphragm peak velocity and CPF (P < .001, adjusted b coefficient 1.71, 95% CI 1.91-2.24, adjusted R 2 5 0.235). The areas under the curves of PCED, diaphragm peak velocity, and CPF for extubation failure were 0.791 (95% Cl 0.668-0.914), 0.587 (95% Cl 0.426-0.748), and 0.765 (95% Cl 0.609-0.922), respectively. CONCLUSIONS: PCED on ultrasonography was significantly associated with CPF and extubation failure after a successful SBT. Future studies should investigate if this method is applicable for determination of tracheostomy decannulation in stable patients in general wards.

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Background: A cough peak flow (CPF) of <60 L/min was significantly associated with increased risk of extubation failure after a successful spontaneous breathing trial (SBT). Passive cephalic excursion of the diaphragm (PCED), measured by ultrasonography during cough expiration, was reported to predict CPF in healthy adults. We hypothesized that PCED, diaphragm peak velocity, or both, during cough, as measured by ultrasonography, might predict CPF and extubation outcome in mechanically ventilated patients. This study attempted to identify associations of ultrasonographic indices of the diaphragm with simultaneously measured CPF and to investigate the predictive values of ultrasonographic indices for extubation outcomes after a successful SBT.Methods: Two hundred fifty-two (252) mechanically ventilated patients with a successful SBT were enrolled in the prospective cohort study. Right hemidiaphragm passive cephalic excursion and peak velocity were measured by ultrasonography during voluntary cough expiration with maximum effort. CPF was measured simultaneously with ultrasonographic measurements.Results: A multiple regression model adjusted for age and sex showed a significant association between PCED and CPF (P < 0.001, adjusted beta coefficient 11.4, 95% CI 8.88–14.0, adjusted R2 = 0.287) and between diaphragm peak velocity and CPF (P < 0.001, adjusted beta coefficient 1.71, 95% CI 1.91–2.24, adjusted R2 = 0.235). The areas under the curves of PCED, diaphragm peak velocity, and CPF for extubation failure were 0.791 (95% Cl 0.668–0.914), 0.587 (95% Cl 0.426–0.748), and 0.765 (95% Cl 0.609–0.922), respectively.Conclusions: PCED measured by ultrasonography significantly predicted CPF and extubation failure after a successful SBT.

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