Comparing near infrared spectroscopy and transcutaneous oxygen measurement in hard-to-heal wounds: a pilot study

Oxygen plays an integral role in all phases of the wound healing process and tissue oxygenation is a key determinant of wound healing. A comprehensive evaluation of patients with hard-to-heal wounds must include measurement of oxygenation in and around the area of skin breakdown. The current gold standard, transcutaneous oxygen measurement (TCOM), has numerous drawbacks and as a result has fallen into disuse.

This study compared measurement of tissue oxygenation of near infrared spectroscopy (NIRS) with TCOM in patients with acute and hard-to-heal wounds. The Shapiro-Wilk test was used to evaluate the normality of the data. The level of agreement between NIRS and TCOM was determined using Bland-Altman analysis. The relationship between TCOM and NIRS was examined using Pearson correlation.

A total of 24 observations were obtained from 10 patients using TCOM and NIRS. The weighted mean partial pressure of oxygen (pO₂) in the study population was 39.54mmHg (8.96 standard deviation). Bland-Altman analysis showed that mean difference was positive (18.75), suggesting an overestimation of oxygen measurements using TCOM compared with NIRS. The oxygen levels measured by TCOM and NIRS showed a strong correlation (r=0.74).

The wound and hyperbaric community would benefit from a simplified procedure for measuring tissue oxygenation. These findings suggest a strong trend toward correlation between NIRS and TCOM. A further study in a larger population is recommended. NIRS offers several advantages over TCOM. Clinicians have immediate point-of-care visualisation of tissue oxygenation using a handheld device. The procedure takes minutes to perform and is less operator-dependent than TCOM. Finally, NIRS allows measurement of oxygenation in the wound bed, while TCOM does not.