Gas Mask and Chronic Obstructive Pulmonary Disease (COPD): New Understanding on the Respiratory Index Impact?
Condition: Work of Breathing
MeSH terms: Respiratory Aspiration
Study type: Interventional

Summary: 
      Background: The gas mask is used to protect the aiways against respiratory hazards (CBRN
      agents). Within the CBRNE committee, speculations are that unprotected lungs would look like
      to those of COPD patients in post-exposure of some CBRNE agents. The aim of the study was to
      evaluate the impact of the gas mask on respiratory patterns and indexes of the respiratory
      effort. Methods: We are completing our study with 9 COPD patients to evaluate breathing
      patterns, index of respiratory efforts and blood gases. Three conditions have been tested in
      a randomized order: 1x baseline and 2x different canisters, with and without a mask (C4,
      Airboss Defence, Bromont, Canada). Airway pressure, inspiratory and expiratory flows have
      been measured. An esophageal catheter is introduced at the beginning of the study to measure
      esophageal pressure (Peso) and calculate indexes of respiratory effort (PTPeso, WOB). SpO2 is
      continuously measured and capillary blood bases are drawn at the end of each condition. Each
      condition lasts 10 minutes, data of the last 2 minutes at a steady state are considered for
      analyses. Results. We are compiling data and processing them for analysis.
    

Detailed description: 
      The principal way of penetration of CBRNE agents is the respiratory system. The current
      technology of a gas mask has been used to protect the respiratory system as far back as the
      First World War. That originated from Dr Cluny Macpherson's initiatives whom was a Canadian
      military physician.

      The military gas mask is part of the respirator classification but owes its specific
      features. Conventionally, the military gas mask covers a large spectrum of protection aspects
      and matched with their specific canisters. Consequently, gas masks are usually studied
      separately from other respirators and Self-Contained Breathing Apparatus (SBCA). While few
      studies have been about the gas mask technology, no-study addresses it in regards of the
      impact from a bad airway protection and consequences on the respiratory system.

      The gas mask design and its components may lead to these respiratory load issues. At rest and
      from different resistances, what would be the impacts for the work of breathing and gas
      exchange? In order to avoid hypoxemia and hyperoxia, what would be the optimal means to
      restore proper oxygenation? We hypothesised on a: i. Heightened WOB and the respiratory
      demands related to wear of the gas mask; ii. An occurrence of hypoxemia will be manifesting
      during a continuous period. Our goal is to measure the impact of the work of breathing and
      the gas exchange for a gas mask user and also a COPD patient. We also measure what was the
      optimal means for correcting the hypoxemia with a subject.

      9 COPD patients have been participating in a comparison and single-blind randomized
      experimental study. That was approved by the Ethical Review Committee. A written consent is
      obtained for all the subjects prior their acceptance. No rejection has happened during the
      recruiting so far. The eligibility criteria are: i. COPD diagnosis from mild-to-severe FEV
      30-80%). The exclusion criteria are: i. Refusals relate to wear the oesophageal catheter and
      for capillary punctures; ii. Claustrophobia; iii. Oesophageal wounds backgrounds; iv. No
      coronary background and stroke history; v. No face morphology incompatibility with the mask.
      Spirometry and usual health screening is also done before starting the clinical trial.

      Design comprises three 10-minute testing conditions split in two parts. All has been at rest
      and sitting on a chair: i. Baseline without gas mask; ii. Gas mask and Canister A; iii. Gas
      Mask and Canister B. Between the condition a 5-minute wash-out takes place.

      Three five-minute periods is followed to record blood pressure and pulse during the
      conditions. SpO2 is continuously measured with Free O2. Capillary punctures are done at the
      end of each condition. Comfort was also assessed.

      Our main measurements are the WOB performed with a continuous recording of Peso pressure and
      respiratory volumes. Software Acknowledge, version 3.9 serves as acquisition data system and
      analysis are achieved with a 4.2 version and a free-trial WOB calculus system, named RESPMAT.
      That is obtained from Maynaud and al.(2014). As power source, we use a BIOPAC (MP100, Santa
      Barbara, Californie, USA, 200 Hertz), four differential sensors (Validyne : 1x MP45±100
      cmH2O; 2x MP100±5 cmH2O; 1x MP100±100 cmH2O) and four Carrier D-Modulators (Validyne,
      CT-15,120 Volt, 60 Hertz, 5Watts, Model CD15-A-2-A-1).

      Single esophageal catheter (Type Cooper, French caliber #5) and disposable pneumotachs are
      used. Lidocain spray and K-Y gel are applied during the insertion of the catheter. Its
      placement is done at 37.6±5.7 cm across the subject and a Mueller test is performed for each
      subject. In regard of spontaneous breathing, an Hudson mask is used while a C-4 Gas Mask with
      a canister was employed (Manufacturer: Airboss Defence, Bromont, Canada). Canister A and B
      were respectively a C7A1 and ADB81 trademark. Prototyped Free O2 System is employed for the
      correction of the hypoxemia.
    

Intervention name(s): measurement of the work of breathing; Gas Mask
Intervention type(s): Other; Device
Intervention description(s): We have been evaluating breathing patterns, index of respiratory efforts and blood gases in all randomized conditions. Airway pressure, inspiratory and expiratory flows have been measured. An esophageal catheter has been introduced at the beginning of the study to measure esophageal pressure (Peso) and calculate indexes of respiratory effort (PTPeso, WOB). SpO2 has been continuously measured and capillary blood bases were drawn at the end of each condition. Comfort has also been assessed. FreeO2 System has been used and pre-programmed in accordance with the patient SpO2 target zone for potential correction of the hypoxemia occurrences. Differences among randomized conditions are one without gas mask as for the baseline and two with gas masks but different canisters.; Differences among randomized conditions are one without gas mask as for the baseline and two with gas masks but different canisters.
Other intervention name(s): Canadian Gas Mask (C4, Airboss Defence, Bromont, Canada) and Canisters (C7A1 and ABD81)
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Single (Participant)
Primary purpose: Health Services Research
Keywords: Work of Breathing; Hypoxemia; Respiratory Acidosis; Respiratory effort; COPD