Test of Chamber Pressure to Divers and Chamber Attendants: A Blinded Trial to Investigate if "Pressure-familiar" Individuals Can Determine Pressure
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Enrollment
- 42
- Locations
- 2
- Primary Endpoint
- Participants Indicating "I do Not Know" on Depth Questionnaire.
Study Overview
Brief Summary
SCUBA divers and chamber inside attendants will undergo a brief hyperbaric chamber excursion and will be asked to what chamber pressure they were compressed and what gas they breathed.
Detailed Description
In clinical trials evaluating hyperbaric oxygen, blinding can be challenging. Options for participant blinding include offering regular air at a lower pressure than the hyperbaric oxygen intervention, or compressing all participants to the same pressure but providing different gas mixes to the active and sham arms.
In some trials of hyperbaric oxygen for brain injury, investigators offer a sham chamber session (regular air at 1.2 atmospheres absolute [atm abs]) compared to the active intervention, hyperbaric oxygen (100% oxygen at 1.5 atm abs). It is unknown whether individuals familiar with pressure changes, such as divers and hyperbaric chamber inside attendants, could discern the difference between these pressures and thereby become unblinded to study allocation.
In this study, 80 experienced divers and chamber inside attendants will be enrolled and randomly assigned to one of four possible chamber pressures and one of two breathing gases. After a brief hyperbaric chamber excursion, they will be asked to what chamber pressure they were compressed and what gas they breathed. If participants can accurately report chamber pressure or breathing gas, pressure-familiar individuals should be excluded from blinded clinical trials of hyperbaric oxygen.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Single Group
- Masking
- Triple (Participant, Investigator, Outcomes Assessor)
Eligibility Criteria
- Ages
- 18 Years to 65 Years (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Adult, age 18 - 65 years
- •Completion of medical history questionnaire without concerns identified for exposure to increased pressure
- •Familiarity with atmospheric pressure change:
- •Experienced and active hyperbaric chamber inside attendant: more than 50 hyperbaric compressions, with more than 4 have been in the last 4 months; or
- •Experienced and active SCUBA diver: more than 20 lifetime compressed gas open water (not swimming pool) dives, with more than 10 in the last 12 months
- •Able to equalize middle ear pressure easily
Exclusion Criteria
- •Pregnancy
- •Known risk for barotrauma, as identified on the medical history questionnaire, such as:
- •Recent (within 12 months) inner ear or sinus surgery
- •Spontaneous pneumothorax
- •Pulmonary cysts
- •Emphysema
- •Bullous lung disease
- •Chronic obstructive pulmonary disease needing chronic active therapy
- •Inability to tolerate chamber confinement or pressure
- •Presence of heart failure
- •Presence of any implanted electrical device, except hyperbaric-approved pacemakers
- •Presence of middle-ear tympanostomy tubes
Arms & Interventions
Sea Level Equivalent 1.2 atm abs (air)
Sham Chamber Session
Sea Level Equivalent 1.2 atm abs (2.6 psig) breathing regular air 20-chamber excursion
Intervention: Sham Chamber Session (Drug)
Sea Level Equivalent 1.5 atm abs (O2)
Hyperbaric Oxygen (1.5 atm abs)
Sea Level Equivalent 1.5 atm abs (6.2 psig) breathing 100% oxygen 20-minute chamber excursion
Intervention: Hyperbaric Oxygen (1.5 atm abs) (Drug)
Altitude Equivalent 1.2 atm abs (air)
Sham Chamber Session
Altitude Equivalent 1.2 atm abs (5.1 psig) breathing regular air 20-minute chamber excursion
Intervention: Sham Chamber Session (Drug)
Altitude Equivalent 1.5 atm abs (O2)
Hyperbaric Oxygen (1.5 atm abs)
Altitude Equivalent 1.5 atm abs (9.6 psig) breathing 100% oxygen 20-minute chamber excursion
Intervention: Hyperbaric Oxygen (1.5 atm abs) (Drug)
Outcomes
Primary Outcomes
Participants Indicating "I do Not Know" on Depth Questionnaire.
Time Frame: Within 15 minutes of chamber excursion
Participants indicating "I do not know" on depth questionnaire instead of providing a free response guess.
Participant Perception of Depth
Time Frame: Within 15 minutes of chamber excursion
Mean depth perception for participants providing a free response.
Participant Perception of Breathing Gas
Time Frame: Within 15 minutes of chamber excursion
Percent of participants in each arm guessing that their breathing gas was 100% oxygen.
Secondary Outcomes
No secondary outcomes reported