Evaluation of vascular compromise in the injured extremity: a photoplethysmographic technique

A monitoring technique in which an infrared photoplethysmograph (PPG) is used to assess the vascular status of injured extremities is described. PPG has been correlated with blood flow in the forearm muscle and direct measurements of compartment pressure. These studies show a significant decrease in amplitude of the PPG signal with diminished blood flow in muscle and with compartment pressures greater than 40 mm Hg. We used PPG clinically on 55 extremities injured by direct vascular trauma, crushing forces, or severe burns. Although clinical signs suggested use of escharotomy in six of 29 burned extremities, normal PPG signals were present and conservative management resulted in no long-term morbidity. Three limbs had moderate pulsatile flow shown by PPG that significantly diminished over a period of 12 to 24 hours even though Doppler flow signals remained strong. Good pulsatile flow was restored in all cases after early escharotomy . PPG monitoring of vascular status is simple and reproducible and accurately reflects levels of ischemia in injured extremities.