Peliai P

N-acetylcysteine administration prevented a rise in thiobarbituric acid reactive substance (TBARS) following hyperbaric oxygen therapy.

Clinical Bottom Line:

1. Evidence that the plasma concentration of a marker of oxygen free radical stress is not raised in patients who are given N-acetylcysteine during their course of hyperbaric oxygen.

Appraised by: Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital

Sydney; Thursday, 22 July 1999

Clinical Scenario: A patient receiving hyperbaric oxygen therapy.

Three-part Question: When patients are undergoing hyperbaric oxygen therapy, does the administration of N-acetylcysteine reduce the extent of lipid peroxidation of the tissues that results from oxygen radical damage?

Search Terms: Hyperbaric oxygenation, oxygen free radicals, N-acetylcysteine.

The Study:

Non-blinded randomised controlled trial with intention-to-treat.

Patients having hyperbaric oxygen therapy for a range of conditions (non-acute and non-infective).

Control group (N = 10; 10 analysed): HBO at 2.2 ATA for 90 minutes daily, five days each week to a total of twenty treatments.

Experimental group (N = 7; 7 analysed): As above, but patients also received 1800mg N-acetylcysteine daily.

The Evidence:

Non-Event Outcome Time to outcome HBO group HBO and NAC group P-value

Thio-barbituric acid

reactive substance

(microm/l) 4 weeks 2.18 1.38 <0.01

TBARS change over

treatment period

(microm/l) 4 weeks 1.02 -0.16 not given

Comments:

1. Apparently no attempt to blind patients, although it is difficult to see how this might affect the result.

2. The clinical significance of this finding is unknown, but the authors remark that there was no clinical evidence of harm.

3. No mention of side-effects of the N-acetylcysteine administration in the abstract. (Full text available only in Italian).

Expiry date: March 2003

References:

1. Peliai P, Rocco M, De Blasi R, Spadetta G, Alampi D, Araimo F, Nicolucci S. Assessment of lipid peroxidation in hyperbaric oxygen therapy: protective role of N-acetylcysteine. Minerva Anestesiologia 1995; 61:133-139.