Test of Chamber Pressure to Divers and Chamber Attendants

Traumatic Brain Injury Clinical Trial

— TOP-DIVER  

Official title:

Test of Chamber Pressure to Divers and Chamber Attendants: A Blinded Trial to Investigate if "Pressure-familiar" Individuals Can Determine Pressure

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01430325
• Other study ID #: 1023955
• Status: Completed
• Phase: N/A
• First received: September 2, 2011
• Last updated: February 12, 2013
• Start date: July 2011
• Est. completion date: October 2011

Study information

• Verified date: December 2012
• Source: Intermountain Health Care, Inc.
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Institutional Review Board
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 42
• Est. completion date: October 2011
• Est. primary completion date: October 2011
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 65 Years

Eligibility

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

Study Design

Allocation: Randomized, Intervention Model: Single Group Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor)

Related Conditions & MeSH terms

• Traumatic Brain Injury

Intervention

Drug:
• Hyperbaric Oxygen (1.5 atm abs)
Hyperbaric oxygen (100% oxygen) delivered at a chamber pressure of 1.5 atm abs.
• Sham Chamber Session
Sham control chamber session: regular air delivered at a chamber pressure of 1.2 atm abs

Locations

Country	Name	City	State
United States	Intermountain Medical Center	Murray	Utah
United States	LDS Hospital	Salt Lake City	Utah

Sponsors (1)

Lead Sponsor	Collaborator
Intermountain Health Care, Inc.

Country where clinical trial is conducted

United States, 

References & Publications (4)

Clarke D. Effective patient blinding during hyperbaric trials. Undersea Hyperb Med. 2009 Jan-Feb;36(1):13-7. — View Citation

Jansen T, Mortensen CR, Tvede MF. It is possible to perform a double-blind hyperbaric session: a double-blinded randomized trial performed on healthy volunteers. Undersea Hyperb Med. 2009 Sep-Oct;36(5):347-51. — View Citation

Weaver LK, Churchill SK, Bell J, Deru K, Snow GL. A blinded trial to investigate whether 'pressure-familiar' individuals can determine chamber pressure. Undersea Hyperb Med. 2012 Jul-Aug;39(4):801-5. — View Citation

Weaver LK, Hopkins RO, Churchill S, Haberstock D. Double-Blinding is Possible in Hyperbaric Oxygen (HBO2) Randomized Clinical Trials (RCT) Using a Minimal Chamber Pressurization as Control. Undersea Hyperb Med 1997;24(Suppl):36.

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Participants Indicating "I do Not Know" on Depth Questionnaire.	Participants indicating "I do not know" on depth questionnaire instead of providing a free response guess.	Within 15 minutes of chamber excursion	No
Primary	Participant Perception of Depth	Mean depth perception for participants providing a free response.	Within 15 minutes of chamber excursion	No
Primary	Participant Perception of Breathing Gas	Percent of participants in each arm guessing that their breathing gas was 100% oxygen.	Within 15 minutes of chamber excursion	No