Near-infrared spectroscopy to assess tissue oxygenation in patients with polytrauma: relationship with outcome

Introduction

We evaluated tissue oxygenation by means of near-infrared spectroscopy (NIRS) and explored its relationship with outcome in polytrauma patients.

Methods

A prospective observational study; 37 polytrauma patients underwent NIRS monitoring (thenar eminence) every day during their stay in the ICU. A VOT was performed with a 40% tissue oxygen saturation (StO₂) target. Healthy volunteers (n = 27) were studied as controls.

Results

StO₂ increased over the first 7 days only in hospital survivors (n = 29), who showed higher values as compared with healthy volunteers at days 5 and 7 (Figure 1). StO₂ downslope and upslope tended to be lower in H-nonsurvivors (n = 8) (P < 0.05 at days 2 and 4) as compared with H-survivors. Tissue hemoglobin index was lower in H-no survivors over the first 7 days and tended to normalize only in H-survivors (P >0.05 vs. healthy at day 7). Five patients were discharged from the ICU but did not survive until H-discharge. At discharge from the ICU, these patients were similar to H-survivors in SOFA score, heart rate, mean arterial pressure and lactate, but showed lower StO₂ downslope (-13 (-16.5, -11.7)%/minute vs. -8.6 (-11.7, -6.5)%/minute, P = 0.01).

Figure 1

Conclusion

An increase in StO₂ and lower tissue oxygen extraction rates were associated with H-survival in polytrauma patients.