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Pressure Sores

A good solid negative for vitamin C and ultrasound

In a previous Bandolier ( #6 , July 1994) we reported on five reviews of pressure sores and an RCT of a pressure relieving bed which showed a very positive effect for that device. Like leg ulcers, a range of different treatments have been used to heal pressure sores, and amongst these vitamin C supplementation and ultrasound have been suggested.

We are delighted to have received a report of two more RCTs on these issues from Dr Gerben ter Riet, of the University of Limburg in Maastricht, working with Dr Paul Knipschild who is well known for his work on systematic reviews in healthcare.

The RCTs are contained in a published thesis which has an excellent review of the literature and extremely detailed trial design and reports on the validity of the models and practical problems faced in the conduct of this sort of study.

Vitamin C

Vitamin C has been thought of as being useful in pressure sore management, and the outline research results on which this was based were reported in Bandolier 6 .

In this RCT, patients with pressure sores graded II, III or IV were recruited from nursing homes and a hospital in southern Holland. Patients with more than one ulcer had the worst chosen for inclusion, mainly those on the trunk. There were a number of exclusion criteria, including patients already taking more than 50 mg of vitamin C supplementation a day and those who were unlikely to survive for the 12-week observation period.

Allocation of patients to active treatment or standard therapy was random, within a block design to ensure between group similarity. Active and placebo tablets were identical in colour, taste, disintegration time and friability, except that active medicine contained 500 mg ascorbic acid, while the placebo tablets contained only 10 mg. Tablets were taken twice daily. Topical wound care was mostly undertaken by the same doctor/nurse team.

Colour slides were taken of the wounds at the start and 1, 2, 4, 6, 8, 10 and 12 weeks, and pressure sore areas and volumes were measured. A number of effect measures were used, and subjective measures were made by independent assessors.

In 1991 and 1992, 88 patients were randomised. In the active treatment group, plasma vitamin C levels rose by 11.3 mg/L in the first two weeks, compared with 0.9 mg/L for the control group over the same period. Mean stable levels in the active group were about 15 mg/L compared with about 5 mg/L in the controls.

While there was comparability between the active and placebo groups, no difference was found in the rate of wound healing by any of the many parameters used to measure it.

While an absolute deficiency of vitamin C may delay wound healing, supplementation beyond 10 to 20 mg per day does not speed up healing.

Ultrasound

Part of Dr ter Riet's thesis concerned the beliefs of healthcare professionals in Holland concerning treatments thought to be effective for pressure sore healing. Ultrasound was thought to be effective by 20% of nursing home physicians and 25% of supervisory nurses; 50% of physicians and 33% of the nurses thought it was ineffective, so a clear disagreement over the place of ultrasound existed. Few RCTs have examined this.

The same criteria were used as for vitamin C above. The ultrasound protocol used was approved by a sample of Dutch education centres for physiotherapy, and patients were treated once daily with ultrasound according to the standard protocol; 75% of the treatments were given by the same operators. The ultrasound device had 20 codes randomly divided over the two treatment options, active or sham, and active and sham use could not be distinguished except by deliberately testing for active ultrasonic production.

Again there was comparability between the groups (88 patients randomised between the two treatments). There was no difference between the groups in any of the ulcer healing parameters studied.

Conclusion

These studies show conclusively that large doses of vitamin C and ultrasound are not effective in promoting ulcer healing. These are good, solid negative results which should not require further investigation. Neither should be purchased for pressure sore management or prevention.

Reference:

G ter Riet, AGH Kessels, P Knipschild. Vitamin C and ultrasound in the treatment of pressure ulcers. Cip-data Koninklijke Bibliotheek, Den Haag. ISBN 90-74130-11-9.
Contact Dr Gerben ter Riet Department of Epidemiology University of Limburg PO Box 616 6200 MD Maastricht The Netherlands



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