Pulmonary embolism (PE) is a process where a clot, usually blood, forms within the body and eventually travels to the pulmonary vasculature. The clinical presentation of PE ranges from lack of symptoms to acute hemodynamic compromise and death. Operations that demonstrate a higher incidence of pulmonary embolism include acute spinal cord injury, trauma, neurosurgery, hip fracture repair, total knee arthroplasty, and total hip arthroplasty. Because of its sometimes vague symptomatology, clinicians should maintain a high level of clinical suspicion for a possible intraoperative PE.
The etiology for the vast majority of pulmonary emboli stem from thromboembolic events, usually a deep vein thrombosis. The basis for all thromboses in the body is described via “Virchow’s triad”: hypercoagulability, hemodynamic changes (e.g., venous stasis), and endothelial dysfunction. Once a deep vein thrombus begins to form in the lower extremity, parts of the newly formed thrombus can break off and travel in the venous system to the heart. Once at the heart, the clot can pass through to the lungs and become lodged within the pulmonary artery or one of its branches, ultimately leading to ischemia within the lungs. Risk factors for developing DVTs include malignancy, surgery, traveling for long distance, and inherited hypercoagulable disorders. Because the venous system depends on muscular contraction to move blood forwardly, prolonged immobilization can lead to blood stasis and clot formation.
Pulmonary fat emboli usually occur after traumatic injury to the musculoskeletal system or after a surgical procedure. Fractures of the pelvis and long bones are especially susceptible to producing fat embolus, often leading to fat embolism syndrome (FES). Fat emboli are usually small and multiple, leading to damage to multiple functional systems including pulmonary, dermatological, and neurological. Diagnosis is difficult, but petechiae are a common feature since the small fatty emboli lead to microhemorrhages in the skin. If fatty emboli reach the pulmonary vasculature, catastrophic consequences may ensue including cor pulmonale and sudden death. The exact pathophysiology of fat emboli origin is still not fully elucidated; however, the general principle includes the idea that after a skeletal injury, intramedullary pressure rises, forcing fat globules into the venous system. Once in the venous system, the fat globules have the potential to advance into pulmonary vasculature, leading to symptoms of pulmonary embolism.
Pulmonary air embolism occurs when air becomes entrapped in the venous or arterial circulation. This occurs most often in the surgical setting when air is introduced into an intra-arterial or intravenous line, or when air gets entrapped directly into the surgical field. Air emboli are not very common due to the high pressure gradient in the venous and arterial system compared to atmospheric pressure. Veins within the head and neck are the exceptions. These veins typically have pressures lower than atmospheric pressure, allowing a favorable gradient for air to enter the circulatory system. In the surgical setting, especially in laparoscopic procedures, the high ...