Anesthesia for Definitive Trauma Interventions

DEFINITIVE TRAUMA INTERVENTIONS

The physical examination, emergency procedures, and evaluations used to determine the extent of injury, need for an MTP, and surgical intervention all occur outside the operating room. The decision to proceed to the operating room may be the first point in the trauma resuscitation process at which an anesthesiologist is involved. Key issues in the anes-thetic management of trauma patients include the need to avoid vasopressors and minimize crystalloid infusions until bleeding is controlled. Blood prod-ucts are the fluids of choice for trauma resuscitation.

Anesthetic Induction & Maintenance

Conscious and oriented trauma patients arriving for emergent surgery should have an abbreviated interview and examination, including emphasis on consent for blood transfusions and advice that intra-operative awareness may occur during emergency surgery. This discussion should be documented in the patient’s record.

The operating room should be as warm as is practical. Intravenous fluid warmers and rapid infu-sion devices should be used. All patients arriving for trauma surgery should be presumed to have full stomachs and thus to be at increased risk for aspira-tion. As noted earlier, the presence of a C-collar may increase the difficulty of intubation. Accordingly, robust suction equipment and alternative airway devices (eg, fiberoptic bronchoscopes, videolaryn-goscopes) should be immediately available for use.

Intravenous access is usually established in the prehospital setting or in the emergency department. If the existing peripheral intravenous lines are of suf-ficient caliber and quality for infusing blood under pressure (ie, a 16-gauge or 14-gauge catheter), a cen-tral line is usually not necessary for the initial surgi-cal intervention. Patients may arrive in the operating room so profoundly hypotensive and hypovolemic that peripheral intravenous access is impossible. In this circumstance, a subclavian or an intraosse-ous catheter should be inserted and blood-based resuscitation initiated. The subclavian vein is often preferred for central venous access in profoundly hypotensive patients owing to its position between the first rib and the clavicle, which tends to stent the vein open. An intraosseous catheter is usually seated into the bone marrow of the proximal tibia or humerus, a process that is facilitated by use of a bone drilling device. Use of intraosseous access requires that the bone distal to the intraosseous catheter to be intact; otherwise; extravasation of infused fluid through the fracture site, the path of least resistance, will occur. A pressure bag must be used for infus-ing any fluid through the intraosseous catheter due to resistance to passive flow from the bone marrow, although the intraosseous space is intimately con-nected with the venous system and transfused blood readily enters the central circulation via this route.

Major blood loss and hemodynamic instabil-ity create a dangerous situation for the conscious trauma patient and a challenging decision for the anesthesiologist planning the induction of general anesthesia. Trauma patients with severe injuries are poor candidates for induction with propofol, given the likelihood of profound hypotension following even modest doses (0.25–0.5 mg/kg intravenously). Etomidate preserves sympathetic tone, which makes it a modestly safer choice than propofol. Ketamine is also a reasonable choice, particularly if given in 10-mg intravenous boluses until the patient becomes unresponsive. Scopolamine, 0.4 mg intravenously, should be considered as an amnestic agent for the hemodynamically unstable but conscious patient at high risk for hemodynamic collapse on induction of anesthesia who arrives in the operating room for emergency surgery. What is most important is not the particular intravenous anesthetic induction agent chosen, but recognition that the hemody-namically unstable trauma patient will require sig-nificantly less anesthetic medication than in normal circumstances.

An arterial line will be helpful but insertion may prove difficult in the hypotensive, hypoper-fused trauma patient. Attempts at placing invasive monitors can continue as the patient is prepped for surgery and the surgeon begins the operation. If halted, attention should focus on transfusion-related efforts.

Damage Control Surgery

If the trauma patient requires emergent laparotomy for intraabdominal hemorrhage, the trauma surgeon will perform an abbreviated procedure termed dam-age control surgery (DCS), which is intended to stophemorrhage and limit gastrointestinal contamina-tion of the abdominal compartment. After making a midline incision, the surgeon quickly searches for sources of bleeding through a quadrant-by-quadrant examination. Communication between the surgeon and the anesthesiologist is essential in DCS; the sur-geon must know if the patient is becoming unstable, hypothermic, or coagulopathic in spite of ongoing resuscitation during the operative procedure. The surgeon will usually compress or pack the area of bleeding if the patient is hypotensive, an interven-tion that usually improves hemodynamics by slow-ing hemorrhage and allowing more rapid restoration of circulating blood volume. If direct compression of the hemorrhaging intraabdominal tissue fails to improve hemodynamic stability, the surgeon can also slow the rate of hemorrhage by compressing the aorta. Compression of the aorta also provides tac-tile information to the surgeon. Particularly in cir-cumstances where invasive arterial monitoring was not accomplished, the surgeon’s fingers on the aor-tic pulse can provide useful information regarding volume status: a soft, compressible aorta represents profound hypovolemia, whereas a firm, pulsatile aorta suggests more normal volume status.

Definitive repair of complex injuries is not part of DCS. Identification and control of injured blood vessels and solid organs, as well as inspection of injuries in areas relatively inaccessible to midline approaches (eg, deep liver lacerations, retroperito-neal hemorrhage) but potentially amenable to inter-ventional radiology techniques, occurs during DCS laparotomy. Hollow viscus injuries are addressed with resection or stapling, or both, to prevent abdominal contamination, often leaving the intes-tines disconnected until the patient is more stable. At that later time, bowel continuity can be restored or colostomy can be performed. At any time during DCS, if the patient becomes unstable or profoundly hypothermic, or if transfusions are insufficient in maintaining perfusion, the operation should be interrupted, the bleeding areas packed, and a deci-sion should be made as to whether the patient can be transferred to the interventional radiology suite to treat bleeding from surgically inaccessible sites or transferred to the intensive care unit to allow warming, treatment of hemodynamic or hemostatic abnormalities, and continuation of resuscitation.

The interventional radiology suite is increas-ingly utilized as part of the DCS sequence, because interventionalradiology techniques can reach essentially any bleeding vessel and deposit coils or foam to control hemorrhage. Most notably, liver, kidney, and retroperitoneal injuries, pelvic ring fractures, and major thoracic and abdominal vas-cular injuries are potentially controlled by inter-ventional radiology procedures. Following DCS, trauma patients will frequently be transferred to the interventional radiology suite to assess blood flow and hemostasis of organs either injured by the ini-tial trauma or potentially compromised as part of the DCS.