Long bone fractures predispose patients to the embolization of contents of the medullary region of bones. Fat emboli are nearly universal after pelvic or femur fractures but the incidence of fat emboli syndrome (FES) is 3%–4% with 10%–20% mortality. The embolic load increases as the space the medulla is drilled or around the time of the application of cement into the medullary canal. Earlier repair of fractures lowers the risk for FES. FES is manifested by hypoxia, mental status changes, and petechiae. The petechiae are present on the conjunctiva, oral mucosa, and/or in the cervical and axillary regions. Transesophageal echocardiography can detect echogenic material which may be fat emboli but the clinical presentation of FES is delayed and thought to be the result of an inflammatory response. FES presents between several hours to 72 hours after the initial fracture. The symptoms can last up to a week and the treatment is supportive care and monitoring for progression to disseminated intravascular coagulation and multiple organ dysfunction.
Methylmethacrylate (bone cement) is sometime used to secure hardware to bones. The use of methylmethacrylate causes intramedullary hypertension and causes the embolization of the contents of the marrow including entrained air. Methylmethacrylate can directly cause hypotension while the embolized medullary contents can cause an inflammatory response which leads to pulmonary hypertension with resulting ventilation to perfusion mismatches and right heart strain. This phenomenon is sometimes referred to an implantation syndrome.
Tourniquet usage is common during orthopedic surgeries to decrease blood loss and provide a bloodless surgical field. Tourniquets cause localized pain and distal ischemia. Tourniquet pain increases over time and becomes clinically significant between 45 and 90 minutes after application. Frequently double tourniquets are used. Initially one tourniquet is inflated but when tourniquet pain becomes clinically evident the second is inflated and the first deflated to try to mitigate the pain. Tourniquet pain causes a sympathetic surge and may be confused with other causes of tachycardia and hypertension. When a tourniquet is released the blood in the affected extremity returns to the central circulation. Returning blood may be acidotic, hypothermic, and hyperkalemic. The bolus of blood from the affected extremity to the heart can cause an acute dysrhythmia that may necessitate the use of intravenous calcium and/or sodium bicarbonate, hyperventilation, and electrical cardioversion or defibrillation. The release of a tourniquet may also cause hypotension through either a rapid decrease in systemic vascular resistance or as a result of direct myocardial depression or both. Patients with sickle cell disease are at risk for vaso-occlusive crises with the use of tourniquets.
Rheumatoid arthritis (RA) is a disease found frequently among patients undergoing orthopedic surgery. Serum rheumatoid factor, erythrocyte sedimentation rate, and c-reactive protein are elevated in most cases of RA. Patients with RA may have decrease jaw ...