Correlation of near-infrared spectroscopy and direct pressure monitoring in an acute porcine compartmental syndrome model

OBJECTIVE: To correlate near-infrared spectroscopy (NIRS) and the tibial intracompartmental perfusion pressure (TIPP) in an acute limb compartmental syndrome. METHODS: Landrace swine were subdivided into 2 groups: plasma infusion (n = 16) and blunt trauma plus plasma infusion (n = 15). NIRS sensors were placed over the craniolateral muscle compartment of proximal both tibiae. Albumin infusion elevated tibial intracompartmental pressures (TICP). Time-synchronized measures of systolic, diastolic, and mean arterial pressures, TICP, and percent oxygenation from each leg were collected. For the blunt trauma group, trauma was induced by dropping a 2-kg weight 30 times from 100 cm directly on the muscle compartment. For each group, a repeated-measures analysis of variance model was used to test differences in the TICP, TIPP, and oxygenation values. Pearson correlations were calculated between TICP and oxygenation and between TIPP and oxygenation. RESULTS: Both models created reproducible increases in TICP and decreases in TIPP. Trauma did not alter TICP, TIPP, or percent oxygenation in the model. NIRS was able to detect significant changes in tissue oxygenation at all the same time points. NIRS was able to detect decreased oxygenation at every TIPP decrease and subsequent increase after fasciotomies. An increase in percent oxygenation was seen in all cases once fasciotomy was performed and TICP was reduced. CONCLUSIONS: NIRS provided a sensitive measure correlating to both an increase and decrease in TICP and TIPP, respectively, in this infusion model. The addition of blunt trauma to the model did not alter the correlations of NIRS values with TICP and TIPP. Fasciotomy produced a rebound in oxygenation values.