Classification and Triage
Musculoskeletal trauma patient can be roughly classified into three types: 1) isolated, closed injuries that require surgical intervention can be done on an elective basis, and trauma team involvement is optional; 2) multiple fractures of major long bones and/or joints, which requires trauma team resuscitation / exclusion of life-threatening injuries, followed by early fracture stabilization when appropriate; 3) multiple fractures of the spine, major long bones and/or joints associated with multisystem injuries, which also requires trauma team management.
Hip injuries are common after high-energy impact. Fracture treatment can be delayed, however dislocation injuries require expeditious treatment in order to avoid avascular necrosis of the femoral head and maximize chances for a good functional outcome – these often require either deep sedation or brief periods of general anesthesia, and often paralysis.
Pelvic fractures can be lethal, thus they should be identified as soon as possible and, if necessary, treated immediately. Pelvic bleeding is usually venous in nature and surgically inaccessible, thus the definitive treatment is angiography (after volume resuscitation and external stabilization).
Closed injuries, which are often missed in the initial exam, should be further examined when discovered. In particular, the orthopedist is interested in the vascular and neurologic condition of the limb. 2/3 of combined orthopedic/vascular injuries in the lower extremity are salvageable.
Open injuries are at increased risk of infection and are usually pulse lavaged and debrided as soon as possible. This does not have to occur in the operating room, however, and often can be done at the bedside while awaiting triage for more significant injuries.
Anesthesia for Orthopedic Trauma
Most of these patients will arrive intubated and their orthopedic operations will be part of a series of major operations. While elective orthopedic surgery is often amenable to regional anesthesia, emergent surgery is usually not, for several reasons: 1) urgent orthopedic surgery is often done in conjunction with other operations 2) length of operation is not known and 3) post-operative neurovascular exams are not possible in a blocked extremity. Sometimes a combined approach may be beneficial.
As in other patients, the index for suspicion for hypovolemia should be high – in this case it will manifest as intolerance to volatile anesthetics. In patients who can tolerate it (no cardiovascular pathology or neurologic injuries), controlled hypotension should be considered in order to minimize blood loss (reductions of 20 mm Hg below baseline have been shown to be successful [An HS et al. J Arthroplasty 6: 245, 1991]. Keep in mind that the majority of these patients will experience microbemboli of fat and marrow (detectable on TEE), most of which are clinically insignificant but occasionally lead to a massive acute inflammatory response in the lungs and brain (triad of dyspnea, confusion, petechiae, ultimately leading to ALI/ARDS, as well as possibly cerebral edema, confusion, agitation, and coma) – unfortunately there is no specific treatment for fat embolism syndrome, but when symptomatic, supportive treatment (fluids, epinephrine) may be required.
Compartment syndrome is defined as ischemia in an osseofascial muscle compartment induced by increased pressure and unrelieved by analgesia (also may present with edema, paresthesia, loss of sensation). Leg and forearm fractures, crush injuries, and prolonged pressure increase the risk of compartment syndrome. Theoretically, epidural analgesia can increase the risk (or delay the diagnosis) but some authors have shown that compartment syndromes, which are intensely painful, can still manifest under epidural analgesia. [Montgomery CJ and Ready LB. Anesthesiology 75: 541, 1991]
When suspected clinically, compartment syndromes are confirmed by measuring pressures > 35 mm Hg, and if positive an emergent fasciotomy is indicated (and may be limb-saving).
Prolonged muscle pressure / crush injury leads to myoglobinuria, acute renal failure, and consequent electrolyte abnormalities. Recommended treatment is IVF to maintain UOP @ 1-2 cc/kg/hr, and some authors recommend mannitol and/or sodium bicarbonate (to prevent myoglobin precipitation). The major cause of morbidity and mortality in patients with crush injury is infection, however, not renal failure.
Soft Tissue Trauma
The cornerstone of soft tissue trauma management is debridement of all dead or devitalized tissue, oftentimes with the assistance of a vacuum dressing. Sometimes this can be accomplished with sedation but often, for deep dressings, this may require general anesthesia.