Adherence to Intervention and Follow-up in a Randomized Clinical Trial of Hyperbaric Oxygen Versus Sham

Publication Type
Conference Paper
Year of Publication
Churchill, Susan; Weaver, Lindell; Wilson, Steffanie; Lindblad, Anne; Deru, Kayla
Undersea and Hyperbaric Medical Society Annual Scientific Meeting 2017
Date Published
Naples, FL
Undersea and Hyperbaric Medical Society
adverse events; HBO2; hyperbaric oxygen; post-concussive symptoms; TBI; traumatic brain injury


We report chamber- and protocol-related AEs for participants enrolled in a randomized, double-blind clinical trial of HBO2 for persistent post-concussive symptoms (BIMA*).


This study randomized 71 military service members at three sites to forty 60-minute sessions of HBO2 (1.5 ATA, oxygen) or sham (1.2 ATA, air) over 12 weeks. AEs were collected at each in-person or phone study visit. A physician determined injury severity and relationship to chamber sessions/study participation. AEs through the 12-month visit are reported.


Participants underwent 2,145 chamber sessions. No serious AEs (death/hospitalization) were associated with chamber sessions. Twenty-seven participants reported 61 chamber-related AEs: middleear barotrauma (pain or TEED>0) (16 HBO2 participants, five sham participants), sinus barotrauma (seven HBO2, three sham), headache (one HBO2, two sham), dizziness/vertigo (one HBO2, two sham), vision change (one HBO2, one sham), somnolence (one HBO2, one sham), dyspnea (one HBO2), neck irritation (one sham), eye pruritis (one sham), hyperventilation (one HBO2), and anxiety (one HBO2). Three additional AEs were associated with the test of pressure before randomization: two middle ear and one sinus barotrauma. One HBO2 participant discontinued intervention at 33 sessions for myopia (Snellen change 20/13 to 20/15, no change by autorefractor). Barotraumas were mild and non-limiting. No participant reported chamber claustrophobia.

Fourteen AEs were associated with the study assessment battery:

· ECG: skin irritation from pad adhesive (5)

· computed tomography: anxiety (3), infusion site extravasation (1)

· vestibular testing: dizziness (1), syncope (1), claustrophobia (1)

· blood collection: dizziness (1)

· overall assessment battery: fatigue (1)

AEs unrelated to study participation/intervention were common: 35 HBO2 participants (97%) and 34 sham participants (97%) reported AEs between enrollment and the 12-month visit, but 353/433 recorded AEs (82%) were unrelated acute illnesses or injuries.


AEs in this study were rare, and chamber exposures were safe in this population. The assessment battery was well tolerated.

* BIMA is the Brain Injury and Mechanisms of Action of Hyperbaric Oxygen