Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

Table 60 Therapeutic protocols used in intervention and comparison groups in included studies
focusing on the use of HBOT in sudden deafness and acoustic trauma.*
First Author and Year
of Publication
Cavallazi 1996 95
Vavrina 1995 96
Hoffmann 1993 97 (acute)
Hoffmann 1993 98
(chronic)
Intervention Group Comparison Group
n=32
Comparison therapy plus treatment in an
unstated chamber HBO device at 2.5 ATA for
60 minutes, 15 sessions over 3 weeks.
n=36
Comparison therapy plus treatment in a
multiplace HBO chamber at 1.4 - 2.2 ATA for
60 minutes for 5-10 sessions.
n=10
Treatment in a multiplace HBO chamber at 1.5
ATA for 45 minutes, five times a week for 10-
20 treatments.
n=22
Treatment in a multiplace HBO chamber with
oxygen at 1.5 ATA for 45 minutes, 5 days a
week, for 15 treatments
* Abbreviations: ATA = atmosphere absolute, n = sample size
n=30
Heparin, betamethasone, nicotinic acid,
flunarizine, dextran, vitamins,
neurotropic, and antiviral drugs.
n=42
Initially, 150 mg cortisone intravenously
followed by ginkgo extracts in saline or
dextran. 80 mg oral cortisone after the
first day.
n=10
No treatment.
n=22
Treatment in a multiplace HBO chamber
with air at 1.5 ATA for 45 minutes, 5
days a week, for 15 treatments
Comparison therapies used were very dissimilar. One of the papers by Hoffmann et al, 97
for instance, stated that the comparison group received no therapy for their condition,
while another paper 98 by the same authors made use of a sham procedure as a
comparison. The two remaining studies studied HBOT as an adjunct to
pharmacotherapy. The choice of drugs was interesting given that no particular agent,
apart from corticosteroids and fluid therapy, has been shown to be effective in the
treatment of the condition. In Vavrina et al, 96 cortisone, ginkgo extracts and dextran were
used. Cavallazzi et al 95 identifies up to nine agents including vitamins and antiviral drugs.
Assessment of heterogeneity
Several difficulties prevented the performance of a statistical pooling of results. Firstly,
there were differences in the study designs of the collected studies. The poorly described
methodology raised the possibility of systematic differences affecting one group or
another. Secondly, one of the studies made use of entry criteria that produced a study
population known to have a chronic form of the disorder. Lastly, the comparison
therapies used were very dissimilar – ranging from no treatment, to placebo therapy, to
the use of multiple pharmacologic agents.
Any combination of pairs of articles exhibited at least one of the difficulties mentioned
above. The results of each article are described below.
Review of published clinical experience
Hoffmann et al examined changes in objective hearing ability at four frequencies (500,
1000, 2000, and 4000 Hz) and subjective tinnitus between intervention and comparison
groups. In their study enrolling patients with acute conditions, 97 the authors reported
that 3 of 10 subjects in the intervention group experienced hearing improvements of
more than 20 decibels compared to none in those not receiving any therapy. A similar 30
percent more subjects in the intervention group reported improvement in subjective
60 Hyperbaric oxygen therapy