Session I - Combined Session (International Society for Fracture Repair)
*Near Infra-red Spectroscopy in the Diagnosis of Acute Compartment Syndrome
Matthew J. Hope, MRCSE; Carol Hajducka, RN; Hamish Simpson, MD; Margaret M. McQueen, MD, FRCS; Royal Infirmary of Edinburgh, Edinburgh, United Kingdom (a-Hutchinson Technology)
Purpose: Near-infrared spectroscopy (NIRS), which measures soft tissue oxygenation (StO2) noninvasively, is potentially a new noninvasive technique for the early detection of acute compartment syndrome (ACS). Animal models of ACS have shown that StO2 correlates with perfusion pressure in the compartment. The first part of this study examined intracompartmental pressure and StO2 among patients at risk of ACS. The second part investigated the influence of subcutaneous and intramuscular hematoma on NIRS in an ACS animal model.
Methods:
1) Adult patients with tibial or radial diaphyseal fracture or gross soft tissue swelling were recruited on admission to the orthopaedic trauma unit. Noninvasive and invasive monitoring were carried out from admission until a minimum of 24 hours postoperatively. The differential pressure (DDP) was calculated as the compartment pressure subtracted from the diastolic blood pressure. The threshold for fasciotomy was a 'DDP' <30mmHg. StO2 values were simultaneously recorded from the contralateral (uninjured) limb at the same site. The difference between the StO2 value on the injured and uninjured sides was calculated (StO2 difference).
2) Fifteen adult pigs were divided into three equal groups: plasma infusion alone, plasma infusion with SC hematoma (15 ml of blood) and whole blood infusion (intramuscular hematoma). An ACS was induced under general anesthesia by the above infusion into the anterior compartment of one rear leg of each animal. On both legs noninvasive StO2 and compartment pressure monitoring were carried out. The development of an ACS was confirmed by absence of muscle twitch on electrical stimulation. Fasciotomy was performed 30 minutes later. DDP and 'StO2 difference' (calculated as above) were compared.
Results: 1) Three patients with thigh swelling, 73 with tibial fracture, and 2 with forearm fracture were recruited.
Mean 'StO2 difference' |
(%) |
Mean 'DDP' |
(mmHg) | |
| no fasciotomy (N = 59) | 10.0 |
P = 0.003 |
52.6 |
P < 0.001 |
| fasciotomy (N = 18, all leg) | -2.7 |
24.5 |
2) An acute compartment syndrome was confirmed in all animals.
| Plasma infusion (N = 5) | r = 0.754 |
P = 0.01 |
| Plasma infusion + SC hematoma (N = 5) | r = 0.004 |
P = 0.95 |
| Intramuscular hematoma (N = 4) | r = 0.516 |
P = 0.01 |
Discussion/Conclusion: The StO2 difference (measured noninvasively) was significantly lower among patients with an ACS, suggesting that NIRS can detect decreasing tissue oxygenation in trauma patients who are developing an ACS. The animal study confirms a strong correlation between DDP (mmHg) and StO2 difference (%) in a plasma infusion and an intramuscular hematoma model. This correlation was lost in the presence of a SC hematoma. We are optimistic that NIRS will prove to be a reliable new noninvasive technique for the early detection of an acute compartment syndrome. The localization and avoidance of areas of SC hematoma will improve the diagnostic accuracy of NIRS in acute compartment syndrome.