Review Question - QID 3282

All of the options listed except for Paco2 >35mmHg are indications of a pulmonary embolism. Most patients are hypoxic (Pao2 < 80 mm Hg), hypocapnic (Paco2 < 35 mm Hg), and have a high A-a gradient (> 20 mm Hg).
Pulse oximetry is not a reliable option to arterial blood gas measurements because patients can hyperventilate to maintain adequate oxygenation. Protein C deficiency is an inherited thrombophilia that increases the risk of venous thromboembolism(VTE). This patient is also at risk for VTE secondary to his sedentary status in the ICU and contraindication to administration of chemical VTE prophylaxis because of his subarachnoid hemorrhage.

The review article by Della Rocca and Crist notes that conversion of the external fixator to an intramedullary implant may be accomplished safely within 2 weeks without an increased rate of infection. In the event, there would be suspcicion of an intraoperative pulmonary embolism, correct treatment includes adhering to the principles of damage-control orthopaedics and changing operative plans to a provisional (e.g. external fixator) from a definitive treatment (e.g. intramedullary nail) and obtaining a helical chest CT scan promptly.

The article by Knudson et al is a prospective study of 113 trauma patients that received either SCD's or low dose heparin for DVT prophylaxis. They found no statistical difference between the 2 groups in preventing thromboembolism. They did find that patients with thromboembolism were older, spent more hospital days immobilized, and received more transfusions. High-resolution (helical or spiral) chest CT angiography has become the first line modality for diagnosing pulmonary embolism and should be performed after the operation.