Austin Hagen

Introduction. Patients with trauma to the lower leg may develop Acute Compartment Syndrome (ACS). Prompt diagnosis of ACS is critical to ensuring these patients receive fasciotomy to avoid complications such as paralysis.¹ Clinical Signs of ACS alone have poor sensitivity and specificity, may be unattainable in obtunded patients, and are often late findings.² Currently, diagnosis is confirmed by measuring intracompartmental pressures (ICP) using needles connected to pressure monitors. Conversely, Near-Infrared Spectroscopy determines the current regional tissue oxygenation (rO­₂) non-invasively. NIRS could prove to be a useful tool for physicians to non-invasively and accurately monitor patients with leg trauma for the development of ACS. The aim of this paper is to determine current progress in using NIRS for diagnosis of ACS. Methods. The following five studies were considered. A.) 26 Patients enrolled with unilateral tibia fractures and no ACS. NIRS measurement of rO­₂ performed bilaterally.³ B.) 25 patients with surgically stabilized tibial fractures without ACS had NIRS values taken bilaterally 48 hours post-operatively.⁴ C.) ACS induced through fluid injection into 15 dogs’ legs and direct measurement of O₂ taken.⁵ D.) NIRS measurements taken on 6 swine legs bilaterally with ACS induced by eliminating blood flow for 6 hours.⁶ E.) FDA trial involving 86 patients with leg trauma, 7 of whom developed ACS. NIRS values taken for 48 hours on all patients bilaterally.⁷ Results. A.) Mean hyperemia of 14-17% rO_2­ seen in compartments of traumatic leg when compared to the compartments of the patient’s non-injured leg. Baseline levels of 55-57% rO₂ seen in non-injured legs.³ B.) At 48 hours, mean increase of 14-16% rO­₂ seen in compartments of the injured limb.⁴ C.) A decrease in partial pressure of oxygen in ACS model from about 40mmHg to 2 mmHg observed.⁵ D.) Hypoemia of injured leg seen in pig model of ACS ⁶ E.) All 7 patients with ACS showed a hypoemia of at least 3% in one compartment.⁷ Conclusion. NIRS reliably showed an increase in rO­_2­ in traumatically injured legs up to 48 hours in humans without ACS while a decrease in rO­₂ was seen in a pig model of ACS. A recent FDA trial showed all 7 patients developing ACS had a hypoemia of at least 3% rO­₂ in injured leg. NIRS shows promise for use as a tool for diagnosis of ACS but will require further research to establish recommendations for when to conduct a fasciotomy.

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