Humidification
of hyperbaric oxygen produced improvement in pulmonary flow after one treatment
but this benefit was not sustained over further treatments.
Clinical Bottom Line:
1.
Some improvement in pulmonary flow characteristics with humidification of
hyperbaric oxygen after the first treatment, but these improvements are not
sustained after subsequent treatments.
2.
Some improvement in FEV1% and FEF25-75% with both dry and humidified oxygen
after the first treatment.
Appraised
by: Mike Bennett, Dept. of Diving and
Hyperbaric Medicine, Prince of Wales Hospital
Sydney; Thursday, 8 April 1999
Clinical
Scenario: A patient for routine
hyperbaric therapy.
Three-part
Question: In patients receiving a course
of hyperbaric oxygen therapy, does the humidification of the inspired oxygen
compared to the administration of dry gases, result in any improvement (or less
deterioration) in respiratory function?
Search
Terms: humidification, breathing
circuits
The
Study:
Non-blinded concealed randomised
controlled trial with intention-to-treat.
Routine patients having
hyperbaric oxygen therapy for the adjunctive treatment of chronic wounds in a
multiplace chamber using a built in breathing apparatus.
Control group (N =13;13 analysed):
Hyperbaric oxygen therapy at 2.5ATA for 95 minutes daily for five days.
Experimental group (N =13;13
analysed): As above but with oxygen on the inspiratory line passing through a
bubble humidifier.
The
Evidence:
Non-Event
Outcomes
Time to outcome
Dry group Humidified
group
P-value
Forced
mid-expiratory
flow
rate after
treatment
(l/min)
Day one
3.43
4.59
0.03
%
change in forced
mid-expiratory
flow
rate
after treatment,
day
1 to day 5 (l/min)
Day five
7.17
-2.87
>0.05
Comments:
1. Cross-over design, but return
to baseline not clearly demonstrated.
2. Hyperbaric oxygen transiently
improved pulmonary flow characteristics, more so if humidified.
3. This study suggests that
there is little advantage in humidification of inspired oxygen during a course
of hyperbaric therapy.
Expiry date: March 2003
References:
1. Shupak A, Abramovich A, Adir Y, Goldenberg I, Ramon Y,
Halpern P, Ariel A. Effects on pulmonary function of daily exposure to dry or
humidified hyperbaric oxygen. Respiratory Physiology 1997; 108:241-246.
