What is the best next step in management for a patient with significant leg swelling and pain after a motor vehicle collision?

In the context of significant leg swelling and pain following a motor vehicle collision, assessing for compartment syndrome is crucial. This condition can occur when there is increased pressure within a muscle compartment, leading to decreased blood flow, nerve damage, and potential loss of muscle function if not addressed promptly.

Measuring leg compartment pressures is the most appropriate next step, as it allows for the assessment of whether the pressures within the muscle compartments are elevated. If compartment pressures exceed a certain threshold, it may indicate the need for fasciotomy to relieve the pressure and prevent permanent damage.

Applying a compression wrap could potentially worsen the situation by increasing compartment pressures, while obtaining a lower extremity arteriogram or performing a CT angiography of the leg would not provide immediate information regarding the compartment pressures and could delay critical intervention if compartment syndrome is present. Thus, measuring the compartment pressures directly addresses the most urgent concern in this scenario.