Changes in tissue oxygen saturation reflect changes in targeted oxygen delivery in postoperatively optimised patients

Introduction

Targeting oxygen delivery in the postoperative period has been shown to reduce hospital length of stay and complications [1]. Using a near-infrared spectroscopy device such as the Inspectra™ 325 allows the measurement of tissue oxygen saturation (STO₂) noninvasively as well as a rudimentary measure of blood flow beneath the probe. It is plausible, then, that changes in oxygen delivery (DO₂) during postoperative optimisation may be reflected in changes in STO₂ and provide a noninvasive surrogate of DO₂.

Methods

All adult patients admitted to the ICU after surgery who underwent protocolised haemodynamic optimisation were included. All patients had STO₂ recorded over the thenar eminence using an Inspectra™ 325 for the first 8 hours of their stay.

Results

We found a significant correlation between the changes in STO₂ and oxygen delivery index (DO2I) over the first 8 hours of intensive care stay (n = 40, correlation coefficient of 0.947, P = 0.0001, Figure 1). We classified patients who achieved DO₂I > 600 ml/min/m² as responders. These responders had higher STO₂ values by 3 hours of optimisation, a change that remained significant throughout the duration of the study (Figure 2).

Figure 1

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Figure 2

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Conclusion

Changes in STO₂ during postoperative optimisation appear to mirror changes in DO₂I and may allow more widespread use of noninvasive tissue oxygenation devices in surgical optimisation.