Weaver2
Blinding of experienced individuals to depth and oxygen breathing was successful.
Clinical Bottom Line:
1. Neither scuba divers or hyperbaric chamber attendants could discriminate actual chamber pressure or breathing gas (air or oxygen). 2. Experienced divers and chamber attendants can be included in blinded hyperbaric trials without compromising blinding.
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.
'Lead author's name:'Lindell Weaver: lindell.weaver@imail.org
'Three-part Clinical Question:'Can individuals with experience as scuba divers or hyperbaric chamber attendants accurately describe chamber pressure and/or breathing air or 100% oxygen, when blinded to both during a dry chamber excursion?
Search Terms:'Randomised trials; blinding
The Study: Single-blinded randomised controlled trial to one of four exposures with ‘intention-to-treat’ analysis.
'The Study Patients:'Adult volunteers with demonstrated ability to ventilate the middle ear.
Experimental group (N = 42; 42 analysed): All participants were exposed to one of four conditions (1.2 breathing air or 1.5ATA breathing 100% oxygen; 1.2atm breathing air or 1.5atm breathing 100% oxygen (altitude adjusted equivalents).Participants answered a questionnaire after exposure.
The Evidence:
Depth estimate:
19/42 (45%) ‘I did not know’ 23/42 (55%) gave a numerical estimate: 3/23 (13%) were within 0.6msw of the true pressure Correlation actual depth to estimate: 0.007 (P=0.98, 95% CI -0.42 to 0.41)
Breathing gas estimate:
40/42 responded (95%): 20/40 (50%) correct. (P=0.94)
Comments:
1. Experienced scuba divers and chamber attendants cannot discriminate between a 1.2 ATA and a 1.5 ATA exposure.
2. Same group cannot discriminate between breathing oxygen and air.
3. These exposures are clinically relevant to trials of HBOT for post-concussive syndromes.
4. It is not clear if higher pressure exposures can be accurately determined by blinded individuals.
Appraised by:'Tobias Cibis and Mike Bennett, HBOEvidence Working Group, Sydney, 17.07.2016
Email: m.bennett@unsw.edu.au
'Kill or Update By:'July 2018
