Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

Table 50 Therapeutic protocols used in intervention and comparison groups in included studies
focusing on the use of HBOT in cluster headaches.*
First Author and
Year of Publication
DiSabato 1997 88
DiSabato 1996 89
* Abbreviations: ATA = atmosphere absolute.
Intervention Group Comparison Group
n=10
Comparison therapy plus treatment in a
multiplace HBO chamber at 2.5 ATA for 30
minutes every 2 days for 15 sessions.
n=7
Treatment in a multiplace HBO chamber at
2.0-2.5 ATA for 30 minutes.
n=4
Indomethacin as rescue medication.
Treatment in a multiplace HBO chamber with
air for 30 minutes every two days for 15
sessions. No pressurisation was used.
n=7
Treatment in a multiplace HBO chamber with
air for 30 minutes. No pressurisation was
used.
Assessment of heterogeneity
The study populations of the two studies are different. Although both groups suffer
from cluster headaches and both are diagnosed using explicit criteria, patients differ in
the chronicity of the condition. A valid argument may be made that the pathophysiology
of these two forms are similar enough to warrant some statement about the global
effectiveness of HBOT on the disease. Unfortunately, as will be noted below, neither
study examined the same end-points.
Review of published clinical experience
In their 1997 study, DiSabato et al88 rely on graphical methods only to present their
clinical data, making derivation of numerical results for further analysis inappropriate.
The mean number of attacks was found to decrease in the intervention group compared
to the comparison group. There was some indication of a carry-over effect, as the mean
number of attacks remained low up to two weeks after treatment was stopped. These
results were reflected in the decrease in the mean number of rescue medications taken
over the week.
The 1996 study 89 measured a surrogate endpoint, the immunoreactivity of substance P,
in patients with episodic cluster headache exposed to either HBOT or normobaric
oxygen. The mean density score was found to be decreased in those exposed to HBOT
(Mean ± SD: 8.57 ± 3.21 versus 15.00 ± 1.63; p = 0.0011). The relationship of this
surrogate endpoint to clinical outcome was unclear.
Summary
These studies provided evidence of a beneficial effect on pain relief and physiochemical
outcomes in patients with some forms of cluster headache exposed to HBOT. Concerns
about the methodology of the studies and their quality strictly limit their usefulness.
These concerns included small sample sizes, inadequate masking, and inability to control
for Hawthorne effects and temporal or measurement bias. Only one of the studies
measured clear, clinically relevant outcomes. More rigorous studies in different settings
and examining more varied outcomes in bigger groups of patients are required to provide
firmer and more generalisable evidence of effect. At this time, the identified evidence is
insufficient to support the use of HBOT in cluster headaches.
Hyperbaric oxygen therapy 53