Clinical trial NCT03554460: Evaluation of CO2 Rebreathing During Exercise With the Increasing Ventilation Assisted by NIV With a Dual-limb Circuit
Official title: Evaluation of Carbon-dioxide Rebreathing During Exercise With the Increasing Ventilation Assisted by Noninvasive Ventilation With a Dual-limb Circuit
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Chronic Obstructive Pulmonary Disease
Lead sponsor: Guangzhou Institute of Respiratory Disease
Sponsor class: OTHER
First posted: 2018-06-13
Enrollment: 8
Sex: ALL
Minimum age (years): 40
Maximum age (years): 80
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: Ventilated by a single-limb tubing with PEV caused CO2 rebreathing to COPD patients during exercise with the increasing ventilation. The aim of this study was to evaluate whether CO2 rebreathing could be avoided with the use of the dual-limb circuit, to provide a theoretical basis of more rational clinical application of NIV in the setting of increasing ventilation(eg, after exercise).

Detailed description: Exercise training is a key component of pulmonary rehabilitation. It has shown signifcant improvements in both exercise tolerance and quality of life in patients with COPD. The intensity of exercise training is of great importance to yield a true physiologic effect. However, in patients with severe COPD, exertional dyspnea and leg fatigue make it impossible for the patient to maintain intensity of training for enough time to achieve a physiologic training effect. NIV has been reported to be used as support for exercise to improve exercise tolerance and respiratory performances in patients with mild-to-severe COPD with inconsistent results. Evidence from previous studies have suggested that NIV with a single-limb circuit with Whisper Swivel II expiratory valve or Plateau exhalation valve assisted during exercise in patients with COPD caused CO2 rebreathing. CO2 rebreathing may have a negative impact on efficacy. Previous studies have proved that exercise tolerance was improved ventilated by NIV with a dual-limb circuit. In theory, NIV with a dual-limb circuit consists of one inhalation limb that introduces air into the patient's airways and one exhalation limb that leads exhaled gas outside of the airways, there is no risk of rebreathing. However, there was no report on whether there's no risk of rebreathing in COPD patients ventilated during exercise by a dual-limb circuit. Therefore, the aim of the study was to determine whether there was no CO2 rebreathing occurred assisted with NIV with dual-limb circuit in patients with stable severe COPD after exercise with exertional dyspnea.

Eligibility criteria: Inclusion Criteria:

* presented clinically stable (no exacerbation in the 4 weeks prior to study
* participation or with no change in medications);
* physician diagnosed COPD, forced expiratory volume in 1s (FEV1) \< 50% predicted; dyspnea as a main symptom that limited daily activities.

Exclusion Criteria:

* subjects with obvious pulmonary bullae demonstrated by chest CT scan or X-ray; examination or facial trauma/malformation, recent facial, upper airway or upper gastrointestinal tract surgery, that would preclude receiving NIV therapy;
* a history of coronary artery disease or cardiac arrhythmias or potential electrocardiographic alterations;
* a history of uncontrolled hypertension, or other respiratory diseases;
* patients with musculoskeletal or neurological disorders;
* failure to comply with the research protocol.

Primary outcomes:
measure: fractional concentration of inspired CO2
timeFrame: Measurements were collected continuously throughout a symptom-limited cycle exercise test （test lasts for about 8-12 min） while subjects breathed through the full face mask. Analyses were made breath by breath during the whole test process.
Secondary outcomes:
measure: inspiratory flow of the inhalation limb
timeFrame: Measurements were collected continuously throughout a symptom-limited cycle exercise test （test lasts for about 8-12 min） while subjects breathed through the full face mask. Analyses were made breath by breath during the whole test process.
measure: expiratory flow of the exhalation limb
timeFrame: Measurements were collected continuously throughout a symptom-limited cycle exercise test （test lasts for about 8-12 min） while subjects breathed through the full face mask. Analyses were made breath by breath during the whole test process.
measure: breathing pattern
timeFrame: Measurements were collected continuously throughout a symptom-limited cycle exercise test （test lasts for about 8-12 min） while subjects breathed through the full face mask. Analyses were made breath by breath during the whole test process.
Other outcomes:
Locations:
city: Guangzhou
country: China
facility: The First Affiliated Hospital of Guangzhou Medical University
state: Guangdong
Study officials:
affiliation: The First Affiliated Hospital of Guangzhou Medical University
name: Rongchang Chen
role: STUDY_DIRECTOR
References: