Please see Bibliography of References for a list of abstracts, manuscripts and posters.
Keller BP, Schuurman JP, van der Werken C. J Wound Care. 2006;15(5):213-217.
Objective: To test whether near infrared spectroscopy (NIRS) is applicable for the examination of the influence of external pressure on oxygenation of the soft tissues in the sacral area.
Method: Tissue oxygenation was measured in 33 healthy volunteers in the prone position. A NIRS probe was positioned over the sacrum and external pressure was applied in I0mmHg increments, from 20mmHg to 200mmHg and then decreased. At each level, tissue oxygen saturation (StO2 was measured. To test reproducibility, the protocol was repeated in six volunteers, in whom the thickness of the soft-tissue envelope at different levels of external pressure was assessed using ultrasound.
Results: There was wide variability in StO2 courses between the 33 subjects, with a non-linear relationship between pressure and StO2. The only consistent finding was that the StO2 was significantly higher after decreasing pressure than at the initial pressure of 20mmHg, which is indicative of reactive hyperaemia. Despite the application of high external pressures, reasonable tissue oxygenation was maintained in 19 of 33 subjects. Reproducibility of the measurements was poor. Comparison of soft-tissue thickness with corresponding StO2 values showed that, with increasing pressure, the percentage decrease in tissue thickness was higher than the decrease in tissue oxygenation.
Conclusion: This study confirms that NIRS is not useful for assessing tissue oxygenation in pressure ulcer research due to unacceptable inter-individual variability and poor reproducibility of measurements.
Declaration of interest: The InSpectra Tissue Spectrometer was provided free charge by Hutchinson Technology (Arnhem, the Netherlands). None of the authors had a financial interest in or link with the company.