Chronic Obstructive Pulmonary Disease
Conditions
Keywords
COPD, CPAP, Diaphragm EMG
Brief summary
Both intrinsic positive end expiratory pressure (PEEPi) and dynamic hyperinflation are considered as inspiratory loads which increase work of breathing in patients with COPD. The application of extrinsic positive end expiratory pressure (PEEPe) supplied by CPAP has been claimed to reduce inspiratory load based on change in esophageal pressure which could be significantly affected by change in lung volume and airflow. The investigator hypothesized that CPAP could increase respiratory load because it increases lung volume.
Detailed description
Objective: To assess the effect of CPAP on respiratory load and lung volume in stable COPD. Methods: Patients with COPD were recruited to breath under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O). Diaphragm EMG, esophageal pressure (Pes) and transdiaphragmatic pressure (Pdi) were recorded using balloon esophageal electrode catheter (Yinghui, Guangzhou, China). End inspiratory lung volume (EILV) was measured directly from a pneumotachograph combined with a three way valve under the different CPAP levels. Sensation of breathing difficulty was also assessed. In an additional study, the effect of airflow on pressure was investigated by a physical mode.
Interventions
DEVICEContinuous Positive Airway Pressure
Patients with COPD were recruited to breath under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O).
Sponsors
State Key Laboratory of Respiratory Disease
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Intervention model description
CPAP treatment
Eligibility
Sex/Gender
ALL
Age
40 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
1. Willing to participate after informed consent 2. Males and females, any race and aged 40-80 years 3. GOLD II-IV COPD (post-bronchodilator FEV1 \< 80 % of the predicted normal, and a post-bronchodilator FEV1/FVC \< 0.70)
Exclusion criteria
1. Patients recovering from acute exacerbation less than 4 weeks. 2. Patients with concomitant pulmonary disease (e.g. lung fibrosis, interstitial lung disorder).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Sensation of breathing effort | 5 minutes after each CPAP level (0, 4, 6, 8 and 10 cm H2O) | Using questionnaire to assess the sensation of breathing effort. Sensation of breath effort of CPAP use was divided into three types corresponding to -1, 0, 1 score respectively, 0 refers to the same sensation as the feeling of breathing at the atmosphere without CPAP; 1 refers to the more difficult sensation to breath at the CPAP condition than at the atmosphere.; -1 refers to the easier sensation to breath at the CPAP condition than at the atmosphere. |
| Diaphragm EMG | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of the electrical activity of the diaphragm (EMG-di) |
| Lung volume | 1-3 minutes after each CPAP level (0, 4, 6, 8 and 10 cm H2O) | measurement of end inspiratory lung volume (EILV) |
| Intrinsic positive end expiratory pressure (PEEPi) | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | PEEPi was calculated from the negative deflection in Pes from the onset of inspiratory effort to the point of zero flow during spontaneous breathing. |
| Inspiratory pressure | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of esophageal pressure and transdiaphragmatic pressure by caculating tidal variations in Pes (∆Pes) and Pdi (∆Pdi) relatived to initiation of effort. |
| Inspiratory work | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | the pressure-time product of the respiratory muscles (PTPes/min) and of the diaphragm (PTPdi/min) were calculated under the Pes and Pdi versus time curve and expressed per minute. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Minute ventilation (VE) | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of minute ventilation |
| Peak inspiratory flow rate | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of peak inspiratory flow rate |
| Respiratory rate (RR) | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of respiratory rate (RR) |
| Tidal volume (Vt) | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of tidal volume |
| Expiratory muscle EMG | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | assessment of the electrical activity of the internal oblique muscle (EMG-obl) and the rectus muscle (EMG-rec) |
| Expiratory pressure | Around 5 minutes signals under the atmosphere pressure and different levels of CPAP (4, 6, 8 and 10 cm H2O) were recorded. | The change in Pga resulting from the contraction of the abdominal muscles during expiration was analyzed |
Countries
China
Outcome results
None listed