Anesthesia for Trauma Patients

Our understanding of the pathophysiology of combat trauma has greatly improved over the past few years and has helped to guide the anesthetic care of trauma patients in need of surgical intervention. Appropriate blood product transfusion ratios, use of pharmacologic adjuncts (e.g., tranexamic acid, and calcium) and other modalities have all improved the survival rates of wounded combatants (1). In the operating room, this resuscitation occurs in the context of providing an anesthetic that minimizes hemodynamic instability in the severely injured patient. It is very important, then, that the anesthesiologist understands their role in the management of this resuscitation continuum.

Trauma anesthesia begins before patient arrival with the warming of the operating room, preparation of anesthetic medications, and routine anesthetic machine checks. As hypothermia is part of a lethal triad that includes coagulopathy and acidosis, it is important to make sure that the operating room (OR) is at a temperature greater than 30˚C. It is also important to have a warmed intravenous (IV) line, forced air warmer, and rapid infuser with warming capability immediately available (2). Standard checks of anesthesia machines and airway equipment must be performed to make sure that vital equipment is ready for immediate use. Establishment of a massive transfusion protocol and effective communication with the blood bank are essential and can improve survival. In addition, awareness of the individual medical treatment facility’s on-hand resources (including walking blood bank) and applicable protocols are key considerations (1).

After a patient is identified for surgery, verification of functioning vascular access and placement of monitoring devices (e.g., oxygen saturation, blood pressure, and electrocardiogram) must occur quickly. There are a variety of sedatives that may be used for the induction of anesthesia. Ketamine (at a concentration of 1 mg/kg) is often the preferred sedative, as it does not decrease systemic vascular resistance to the same extent as other sedative hypnotics (1). Succinylcholine (also at 1 mg/kg) should be sufficient to achieve the neuromuscular relaxation needed to facilitate endotracheal intubation. Rocuronium is a non-depolarizing neuromuscular relaxant that is useful in cases where succinylcholine may be contraindicated (e.g., burns, spinal cord injury, and hyperkalemia) (1). Prompt endotracheal intubation of the trachea following induction mitigates the risk of aspiration. Rapid sequence induction (RSI) with direct laryngoscopy is a safe and effective method to secure the airway of the trauma patient (8). After endotracheal intubation of the trachea and verification of end tidal carbon dioxide, communication with the surgeon ensures that the operation proceeds in a timely fashion. Placement of an orogastric tube at this point may potentially decrease the risk of aspiration (1).

Maintenance of anesthesia can be accomplished via an inhalational volatile agent or via a total IV anesthetic (TIVA). Awareness during anesthesia and the acute pain response can be mitigated during TIVA by assuring that both a sedative hypnotic (e.g., propofol and benzodiazepine) and an analgesic (e.g., narcotic) are being administered. Adequate IV access must be assured immediately (e.g., large bore peripheral IV). If needed, placement of additional IV access or an arterial line can be undertaken without delaying the start of the operation (1). Additionally, sending a baseline set of labs, to include coagulation studies and base excess, at the start of the case can set a reference point for the remainder of the resuscitation. The maintenance of anesthesia and resuscitation can be guided by following the trend in mean arterial pressure (MAP). It is important to maintain a MAP of over 55 mmHG, as lower levels have been associated with acute kidney injury and myocardial injury during anesthetics for non-cardiac surgery (4). It is also advisable to maintain a systolic blood pressure greater than 90mmHg in patients with documented or suspected brain injury, as the presence of such a condition can worsen mortality (1).

Early administration of plasma and platelets is one of the first steps of the resuscitation of the trauma patient. Administration of TXA (an anti-fibrinolytic) over 10 min within 3 hours of injury has been demonstrated to improve survival in a highly powered, randomized trial of international trauma patients (5). Administration of hydrocortisone (100 mg) can improve responsiveness in critically ill trauma patients. It must be noted that massive blood transfusion can result in hypocalcemia due to chelation of calcium by the citrate preservative in packed red blood cells. Administration of 1 gm calcium chloride can correct this potentially life-threatening hypocalcemia, as well as the hypotension associated with it (1). Lastly, timely administration of antibiotics can decrease the incidence of post-operative infections and is part of the anesthetic resuscitation. Agents that are effective against skin flora (gram-positive organisms) or, in the event of bowel injury, gastrointestinal flora (anaerobes and gram-negative organisms) should be considered (1).

During the post-operative stage of the procedure, it may be a good decision to initiate low lung volume ventilation (6 mL/kg) to improve outcomes (1). Communication with the next role of care is vital to maintaining continuity of care. This may involve a face-to-face conversation with the intensive care unit team, or a report transmitted to a critical care air transport team. It is imperative to create a detailed written report/anesthetic record to facilitate transition to the next role of care. Being immediately available in the post-operative period to answer any questions can clarify any issues that may arise.

References

1. Joshua M Tobin, William P Barras, Stephen Bree, Necia Williams, Craig McFarland, Claire Park, David Steinhiser, R Craig Stone, Zsolt Stockinger, Anesthesia for Trauma Patients, Military Medicine, Volume 183, Issue suppl_2, September-October 2018, Pages 32–35, https://doi.org/10.1093/milmed/usy062
2. Rotondo MF , Zonies DH: The damage control sequence and underlying logic. Surg Clin North Am 1997; 77(4): 761–77. Epub 1997/08/01.
3. Sollid SJ , Lossius HM, Soreide E: Pre-hospital intubation by anaesthesiologists in patients with severe trauma: an audit of a Norwegian helicopter emergency medical service. Scand J Trauma Resusc Emerg Med 2010; 18: 30. Epub 2010/06/16.
4. Walsh M , Devereaux PJ, Garg AX, et al. : Relationship between intraoperative mean arterial pressure and clinical outcomes after noncardiac surgery: toward an empirical definition of hypotension. Anesthesiology 2013; 119(3): 507–15. Epub 2013/10/19.
5. Shakur H , Roberts I, Bautista R, et al. : Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage (CRASH-2): a randomised, placebo-controlled trial. Lancet 2010; 376(9734): 23–32. Epub 2010/06/18.