gms | German Medical Science

Background: Water-filtered infrared-A (wIRA) is a special form of heat radiation with high tissue penetration and a low thermal load to the skin surface. wIRA corresponds to the major part of the sun’s heat radiation in moderate climatic zones being filtered by water vapour, see Figure 1 [Fig. 1] (http://commons.wikimedia.org/wiki/File:WIRA-Wiki-GH-017E-en-Spectra-wIRA-sun-halogen-radiators.png). wIRA promotes the healing of acute and chronic wounds both by thermal and thermic as well as by non-thermal and non-thermic cellular effects. wIRA increases tissue temperature (+2.7°C at a tissue depth of 2 cm), tissue oxygen partial pressure (+32% at a tissue depth of 2 cm) and tissue perfusion. These three factors are decisive for a sufficient supply of tissue with energy and oxygen and consequently also for wound healing and infection defense.

Materials and methods: The following effects have been proven in a total of seven prospective studies (of these six randomized controlled studies RCT, the largest study with n=400 patients) with most of the effects having an evidence level of Ia or Ib.

Results: Water-filtered infrared-A promotes normal as well as disturbed wound healing by diminishing inflammation and exudation, by promotion of infection defense and regeneration, and by alleviation of pain (without any exception during 230 irradiations, 18.5 vs. 0.0 on a visual analogue scale VAS 0–100, p<0.000001) with substantially less need for analgesics (52–69% less in the groups with wIRA compared to the control groups in visceral surgery, p=0.000020 and 0.00037 and 0.0045, respectively; 6 vs. 14.5 tablets in venous stasis ulcers of the lower legs, p=0.000002).

Further effects are:

• faster reduction of wound area (in severe burns 90% reduction of wound size after 9 vs. 13 days, p=0.000011; complete wound closure of venous stasis ulcers of the lower legs after 14 vs. 42 days, p=0.000005),
• better overall evaluation of wound healing (surgical wounds: 88.6 vs. 78.5 on a VAS 0–100, p<0.000001; venous stasis ulcers of the lower legs: 85 vs. 67.5 on a VAS 0–100, p=0.012),
• better overall evaluation of the effect of irradiation (79.0 vs. 46.8 on a VAS 0–100 with 50 as neutral point, p<0.000001),
• higher subcutaneous oxygen partial pressure during irradiation with wIRA (at a tissue depth of 2 cm 41.6 vs. 30.2 mmHg, p<0.000001),
• higher subcutaneous temperature during irradiation with wIRA (at a tissue depth of 2 cm 38.9 vs. 36.4°C, p<0.000001),
• better cosmetic result (84.5 vs. 76.5 on a VAS 0–100, p=0.00027),
• lower wound infection rate (single preoperative irradiation: 5.1% (9 of 178) vs. 12.1% (22 of 182) wound infections in total, p=0.017, late wound infections (on postoperative days 9 till 30): 1.7% (3 of 178) vs. 7.7% (14 of 182), p=0.007; postoperative irradiations: 7% (3 of 46) vs. 15% (7 of 48), p=0.21, trend; late wound infections: 0% (0 of 46) vs. 8% (4 of 48), p=0.12, trend),
• faster granulation (90 vs. 80 on a VAS 0–100, p=0.036),
• decreased exudation (30 vs. 55 on a VAS 0–100, p=0.075, trend),
• less coatings/crusts (20 vs. 40 on a VAS 0–100, p=0.070, trend),
• shorter hospital stay (9 vs. 11 days, p=0.022, trend).

Conclusion: wIRA represents a valuable therapy option and can generally be recommended for use in the treatment of acute and chronic wounds.