Introduction
Current markers of occult hypoperfusion following major trauma have serious limitations. Our aim was to evaluate oxygen extraction as a resuscitation endpoint, and predictor of organ failure and mortality following trauma.
Methods
A prospective, noninterventional study of 39 consecutive patients admitted to a Level 1 trauma unit ICU. Blood gas analysis was performed on samples from three locations: central venous line, peripheral venous line, and arterial line. Blood was drawn 6-hourly in the first 24 hours, and oxygen extraction calculated using the Fick equation. Organ failure was assessed using MODS and SOFA scores.
Results
See Table 1. Peripheral, but not central, oxygen extraction with a threshold of 150 ml oxygen extracted per litre of blood distinguished survivors from nonsurvivors on admission to the trauma ICU. Low peripheral oxygen extraction (<150 ml) had an odds ratio for risk of death of 5.3 (P = 0.016, Fisher's exact test) and was associated with higher organ failure scores (P = 0.044, Mann–Whitney U test). A trend of increasing peripheral oxygen extraction was also a strong predictor of mortality (P = 0.019, Mann–Whitney U test) and organ failure (P = 0.003, Mann–Whitney U test).
Table 1.
| Survived | Died | Total | |
|---|---|---|---|
| Extract < 150 ml | 8 | 6 | 14 |
| Extract > 150 ml | 23 | 2 | 25 |
| Total | 31 | 8 | 39 |
Conclusion
With an arterial and venous blood sample, and a simple equation, we have for the first time demonstrated that absolute and serial peripheral oxygen extraction are powerful predictors of organ failure and mortality following major injury.