Anesthesia for adult trauma patients

INTRODUCTION — Although the most critically injured patients are ideally transported to a designated trauma center, anesthesiologists in other hospitals may provide care for a patient who requires immediate surgical or other interventions after traumatic injury [1]. This topic reviews anesthetic management of adult patients with severe or multitrauma injuries. Anesthetic management for other types of trauma (eg, isolated orthopedic upper or lower extremity trauma, burn injuries) is addressed in separate topics. (See "Anesthesia for orthopedic trauma" and "Anesthesia for patients with acute burn injuries".)

Other topics address immediate management of trauma patients upon arrival to the emergency department (ED) and initial decisions regarding diagnostic, surgical, and other interventions:

●(See "Initial management of trauma in adults".)

●(See "Approach to shock in the adult trauma patient".)

●(See "Overview of damage control surgery and resuscitation in patients sustaining severe injury".)

Topics that specifically address bleeding and coagulopathy in trauma patients include:

●(See "Initial management of moderate to severe hemorrhage in the adult trauma patient".)

●(See "Massive blood transfusion".)

●(See "Etiology and diagnosis of coagulopathy in trauma patients".)

PATIENT STABILIZATION AND GOALS — A clear, simple, and organized approach to the trauma patient is used in both the emergency department (ED) and operating room (OR), including assessment of airway, breathing, circulation, disability (eg, neurologic evaluation and cervical spine stabilization), and exposure (eg, hypothermia, smoke inhalation, intoxicants) [2]. Participation of the anesthesiologist at an early stage (eg, at the time of trauma response activation or patient arrival in the ED) provides continuity of care before and after transition to the OR [3]. (See "Initial management of trauma in adults", section on 'Primary evaluation and management'.)

Primary goals in both the ED and the OR include:

●Airway management and lung-protective ventilation. (See 'Airway management' below and 'Lung-protective ventilation' below.)

●Maintenance of hemodynamic stability. This includes management of etiologies of shock after trauma, including; hemorrhagic hypovolemic shock and its sequelae (eg, coagulopathy, hemodilution, hypothermia, and electrolyte and acid-base derangements), obstructive shock due to tamponade, and neurogenic shock due to spinal cord injury.

●Management of bleeding and coagulopathy – (See "Massive blood transfusion" and "Etiology and diagnosis of coagulopathy in trauma patients".)

●Maintenance of normothermia – (See "Perioperative temperature management".)

●Maintenance of adequate cerebral blood flow (CBF), oxygenation, and ventilation to avoid secondary brain injury. Even in the absence of overt evidence of traumatic brain injury (TBI), concussion is common in trauma patients and may be associated with significant changes in cerebral hemodynamics and metabolism [4,5]. (See "Anesthesia for patients with acute traumatic brain injury", section on 'Goals for anesthetic management'.)

●Appropriate treatment during painful interventions – (See 'Management of general anesthesia' below.)

Checklists are often used as cognitive aids to ensure optimal preparation and intraoperative resuscitation of trauma patients (table 1) [6,7].

AIRWAY MANAGEMENT

●Challenges in trauma patients – Urgent airway management in trauma patients may be challenging due to maxillofacial injury or burns, blunt or penetrating neck injury, laryngeal or major bronchial disruption, cervical spine instability, compression of the airway, bleeding due to the initial traumatic injury or multiple subsequent intubation attempts that impair direct visualization of the upper airway, or oropharyngeal and/or laryngeal edema due to burn injury. These acute injuries may create a "difficult airway" or may worsen a pre-existing anatomical predisposition to a difficult airway.

●Approach to airway management – A clearly defined, sequential approach to a patient with airway injury or abnormality is critical, since preoxygenation may be difficult, and any delay in securing the airway may lead to rapidly progressing hypoxemia [8]. Also, prolonged efforts to secure the airway may delay definitive treatment of other life-threatening injuries [9]. Airway management should be performed in tandem with other resuscitative interventions by other team members to reduce untoward outcomes (ie, chest tubes for hemopneumothorax, transfusions for hemorrhagic shock, etc) [10].

General concepts for managing a difficult airway are discussed in a separate topic (see "Management of the difficult airway for general anesthesia in adults"). Specific guidance for difficult airway management has been developed by professional societies including the American Society of Anesthesiologists (ASA) Committee on Trauma and Emergency Preparedness (algorithm 1) [11,12], and the Western Trauma Association (WTA) [10]:

•Functional airway in place – If a patient arrives to the trauma resuscitation area with a functioning rescue airway, definitive airway management may be delayed till after the primary and secondary surveys [10].

•Rapid sequence induction and intubation (RSII) – In some patients, RSII may be appropriate if no difficulty with airway management is anticipated. (See "Rapid sequence induction and intubation (RSII) for anesthesia" and "Induction agents for rapid sequence intubation in adults for emergency medicine and critical care".)

•Conservative airway management – In stable patients without airway compromise, conservative airway management may be suitable. In one review, immediate establishment of a definitive airway was necessary in approximately 50 percent of patients with penetrating trauma and in 80 percent of those with blunt trauma [13]. In another review, approximately one-third of traumatized patients did not require immediate endotracheal intubation in the emergency department (ED), but were instead intubated after transport to the operating room (OR) [14].

Delayed sequence intubation (as opposed to RSII) is a conservative strategy that may be employed for agitated patients in the ED or the OR [15]. First, a dissociative dose of intravenous (IV) ketamine 1.5 mg/kg is administered to facilitate preoxygenation for a minimum of three minutes, then IV succinylcholine 1.5 mg/kg is administered, followed by endotracheal intubation. In a randomized trial of 200 critically injured patients who required definitive airway management, those assigned to delayed sequence intubation were less likely to experience peri-intubation hypoxia compared with those assigned to standard RSII (8 versus 35 percent) [15]. (See "Rapid sequence induction and intubation (RSII) for anesthesia".)

•Indications for a surgical airway – In a patient with life-threatening injuries or hypoxemia, inability to obtain a definitive airway is an absolute indication for emergency cricothyroidotomy or surgical tracheostomy, particularly if a "cannot ventilate, cannot oxygenate" scenario develops [13]. If airway injury is extensive, a joint decision to place a surgical airway distal to the site of injury may be made by the anesthesiologist and the ED clinician and/or trauma surgeon. Factors influencing this decision include the specific airway injury, presence of other traumatic injuries, the patient's overall condition, clinician expertise, and types of immediately available airway equipment. (See "Emergency cricothyrotomy (cricothyroidotomy) in adults".)

We agree with ASA and WTA recommendations to limit intubation attempts in the setting of a failed airway [10,12]. Guidance from the WTA recommends proceeding with a surgical airway if the clinician cannot oxygenate or ventilate either by bag mask ventilation or a rescue airway such as a supraglottic airway, or after three failed attempts to achieve endotracheal intubation [10]. (See "Management of the difficult airway for general anesthesia in adults", section on 'The failed airway'.)

Management of a difficult airway in patients with specific trauma conditions (eg, airway disruption, oral and maxillofacial trauma, airway compression, closed head injury) is described in each of these tables (table 2 and table 3 and table 4 and table 5) [11,16]. Further details regarding airway management for specific traumatic injuries are discussed in separate topics:

•Cervical spine injury (figure 1) – (See "Anesthesia for adults with acute spinal cord injury", section on 'Airway management'.)

•Head trauma – (See "Anesthesia for patients with acute traumatic brain injury", section on 'Airway management'.)

•Burn injury – (See "Anesthesia for patients with acute burn injuries", section on 'Airway management'.)

INTRAVASCULAR ACCESS AND MONITORING — Depending on the clinical presentation, an intra-arterial catheter and a central venous catheter (CVC) are typically inserted in hemodynamically unstable trauma patients undergoing general anesthesia, if not previously inserted in the emergency department (ED). However, central access should not delay control of ongoing hemorrhage. Two large-bore peripheral intravenous (IV) catheters (eg, 16 G or larger) can be rapidly inserted instead of or in addition to a CVC for initial administration of fluid, blood transfusions, and IV vasoactive and anesthetic agents.

If obtaining reliable IV access is difficult, intraosseous access can be rapidly and reliably achieved, and can be used for (blood and fluid) resuscitation and to administer medications (see "Intraosseous infusion") [17-19]. Additional considerations for intraoperative monitoring are discussed separately. (See "Intraoperative management of shock in adults", section on 'Intraoperative monitoring'.)

INTRAOPERATIVE MANAGEMENT OF HEMORRHAGIC SHOCK

Blood and fluid administration — Our approach to hemorrhagic shock focuses on limiting crystalloids, administering blood products to maintain adequate hemoglobin and hematocrit targets, and managing coagulopathy. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Resuscitation and transfusion'.)

For patients with severe or ongoing hemorrhage, red blood cells (RBCs) and other appropriate blood products are transfused as soon as they are available, rather than continuing administration of crystalloid or colloid [20]. Ideally, no more than 1 L of warm crystalloid solution is administered prior to availability of blood components [2]. For patients requiring massive transfusion, RBCs and other appropriate blood products are transfused in a ratio of 1:1:1 (RBCs:plasma:platelet packs). It is critically important to warm all IV fluids and blood to maintain normothermia and avoid hypothermia-induced exacerbation of coagulopathy. (See "Massive blood transfusion", section on 'Approach to volume and blood replacement'.)

Although transfusion is based on the rate of bleeding and laboratory assessments as these become available, we also employ dynamic parameters during the intraoperative period to assess intravascular volume status, guide fluid administration, and avoid fluid overload [21,22]. These include transesophageal echocardiography (TEE) to assess changes in left ventricular cavity size (movie 1) or respirophasic variation in the intra-arterial pressure waveform during positive pressure ventilation (table 6 and figure 2 and figure 3) [23-25]. Thus, fluid overload can be avoided. Although vasopressors may be useful to counteract vasodilation in hemorrhagic and other types of shock, it is essential to achieve an appropriate balance between intravascular volume and vascular tone [26].

Additional details regarding management of hemorrhagic shock are available in other topics:

●(See "Initial management of moderate to severe hemorrhage in the adult trauma patient".)

●(See "Approach to shock in the adult trauma patient".)

●(See "Massive blood transfusion".)

●(See "Etiology and diagnosis of coagulopathy in trauma patients".)

Red blood cells, whole blood, or salvaged blood — Although the transfusion target is a hemoglobin value of 7 to 8 g/dL, immediate life-saving transfusion may be necessary before laboratory assessment of hemoglobin is available when blood loss is rapid and significant. Also, intraoperative blood salvage is often employed [27]. In one trial of patients undergoing emergency abdominal or thoracic trauma surgery, the reduction in the use of allogeneic RBCs in the cell salvage group was 4.7 units (95% CI 1.31-8.09 units), compared with controls [28]. (See "Surgical blood conservation: Intraoperative blood salvage".)

Although the ratio of 1:1:1 (RBCs:plasma:platelet packs) mirrors the content of whole blood, whole blood is a reasonable alternative if available [29-35]. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Moderate to severe ongoing hemorrhage'.)

In this setting, availability of RBCs or whole blood should not rely on a full crossmatch in patients with hemorrhagic shock since uncrossmatched (ie, emergency release) blood can be administered until the crossmatch is complete. It is better to transfuse than allow the hemoglobin to fall below 7 g/dL. The incidence of a hemolytic transfusion reaction in a patient receiving type-specific blood is <1 in 50,000 transfusions and is approximately 1 percent in uncrossmatched O-type blood. However, these risks must be counter-balanced with the known risk of mortality that increases two and a half fold for every g/dL drop below 8 g/dL [36-38]. (See "Indications and hemoglobin thresholds for RBC transfusion in adults", section on 'Impact of anemia on morbidity and mortality'.)

Other blood products and clotting factors — After severe traumatic injury, acute coagulopathy may develop due to multiple factors. These include hemorrhagic hypovolemic shock, rapid depletion of fibrinogen due to hyperfibrinolysis and hemodilution as crystalloid and blood products are administered, platelet dysfunction following platelet activation, hypothermia due to exposure and fluid administration, acidosis, tissue injury causing endothelial disruption, disseminated intravascular coagulation (DIC), and other pathophysiologic processes that generate imbalanced activation of procoagulant and anticoagulant factors [39,40]. (See "Etiology and diagnosis of coagulopathy in trauma patients", section on 'Etiologies'.)

In addition to administration of plasma and platelet packs as noted above, other treatment considerations include:

●Use of antifibrinolytics – Tranexamic acid (TXA) is often administered to trauma patients in the perioperative setting. Data regarding safety and efficacy is presented in other topics:

•(See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Antifibrinolytic agents'.)

•(See "Ongoing assessment, monitoring, and resuscitation of the severely injured patient", section on 'Management of acute traumatic coagulopathy'.)

●Administration of cryoprecipitate or fibrinogen concentrate – If low fibrinogen levels are documented or strongly suspected, fibrinogen supplementation may improve outcomes [41-46]. We treat low fibrinogen concentration <100 mg/dL or fibrinolysis evident on point-of-care (POC) laboratory tests with cryoprecipitate or fibrinogen concentrate [47,48]. (See "Etiology and diagnosis of coagulopathy in trauma patients", section on 'Fibrinogen levels' and "Cryoprecipitate and fibrinogen concentrate".)

●Prothrombin complex concentrates – Due to risk for thromboembolic events, we do not empirically administer a prothrombin complex concentrate as part of the massive blood transfusion protocol, unless the patient was receiving chronic anticoagulant medications [49]. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Moderate to severe ongoing hemorrhage'.)

Point-of-care and standard laboratory testing — In addition to intraoperative hemoglobin (or hematocrit) monitoring, standard coagulation tests and POC viscoelastic tests of hemostatic function are typically employed to allow rapid assessment of causes of coagulopathy and responses to interventions, including transfusion of blood products [43,44,50-58]. The most commonly used POC tests for overall hemostatic function are thromboelastography (TEG) (figure 4 and figure 5 and table 7) or rotational thromboelastometry (ROTEM). (See "Etiology and diagnosis of coagulopathy in trauma patients", section on 'Coagulation studies' and "Ongoing assessment, monitoring, and resuscitation of the severely injured patient", section on 'VHA-based dosing'.)

Intraoperative assessment and treatment of low hemoglobin and or hematocrit values, electrolyte abnormalities, elevated serum lactate level, and acid-base derangements is also helpful to maintain hemodynamic stability [59-62]. Correction of metabolic acidosis is initially accomplished with adequate fluid resuscitation rather than with administration of sodium bicarbonate [63,64]. (See "Intraoperative management of shock in adults", section on 'Target values for resuscitation'.)

Hemodynamic management — In addition to early surgical control of hemorrhage, initial strategies to limit ongoing blood loss include maintenance of a low to normal systolic blood pressure (BP) at approximately 90 mmHg (or ≤110 mmHg in older adults) and/or mean arterial pressure (MAP) at 50 to 65 mmHg [65,66]. Once hemostasis has been achieved, higher BP values are targeted (eg, systolic BP ≥90 mmHg and/or MAP ≥65 mmHg). Notably, although increasing BP indicates increasing macro-circulatory pressure, microcirculatory flow may still be abnormal. (See 'Administration of high-dose opioids' below.)

Vasopressor use in hemorrhagic shock is not a first-line treatment due to concerns regarding worsening vasoconstriction and organ failure in the absence of adequate volume resuscitation [26,67]. However, in patients with vasoplegia or insufficient vasoconstrictive response (eg, patients with neurogenic shock due to spinal cord injury), continuous infusion of low doses of a vasopressor (typically norepinephrine) may be necessary to maintain BP and restore adequate tissue perfusion (table 8). One large retrospective study in trauma patients suggests that norepinephrine use is not associated with an increase in mortality [68]. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Vasopressors' and "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Spinal cord injury in the setting of hemorrhagic shock'.)

In addition to treating hemorrhage, ongoing assessment for other causes of shock is necessary during the intraoperative period if hemodynamic instability persists. Examples include spinal cord injury causing neurogenic (ie, vasoplegic) shock, tension pneumothorax, pericardial tamponade, increased intra-abdominal pressure causing obstructive shock, and severe ischemic myocardial dysfunction causing cardiogenic shock. Management of these additional causes of shock is discussed in detail in separate topics. (See "Approach to shock in the adult trauma patient" and "Intraoperative management of shock in adults".)

MANAGEMENT OF GENERAL ANESTHESIA

General principles — Operating rooms (ORs) in trauma centers should have full monitoring capabilities and be stocked for routine and advanced airway capabilities, as well as with equipment for rapid transfusion, and a variety of catheters for intravascular and intra-arterial access.

General anesthesia is nearly always employed during the intraoperative period in severely injured trauma patients, rather than regional anesthetic techniques (neuraxial anesthesia or peripheral nerve blocks). However, a multimodal approach to analgesia that includes regional anesthetic techniques when feasible is used to decrease postoperative opioid dosing requirements . (See "Anesthesia for thoracic trauma in adults", section on 'Regional analgesic techniques' and "Overview of peripheral nerve blocks".)

Anesthetic agents with minimal hemodynamic effects are selected, and doses are reduced and carefully titrated to avoid exacerbation of hypotension [69,70]. Patients with marginally compensated or overtly decompensated hemorrhagic shock have a smaller volume of distribution for all anesthetic agents. Even after hemodynamic stability has been achieved, careful titration is necessary since the patient's clinical condition may rapidly change. For example, a trauma patient may have unrecognized bleeding into the retroperitoneum after a severe pelvic injury, or into muscle and fascial compartments after bilateral femur fractures.

Induction — The goal of induction of general anesthesia is to produce an unconscious state while maintaining adequate organ perfusion. However, induction may result in profound hypotension and/or cardiac arrest in a patient with poorly compensated hemorrhagic shock. Before beginning induction, many practitioners will connect a vasopressor infusion "in line" in the intravenous (IV) tubing so that it is ready for immediate administration (table 8). In a hemodynamically unstable patient, many administer a bolus dose of a vasopressor concurrently with the induction agents to prevent exacerbation of hypotension. (See "Intraoperative management of shock in adults", section on 'Induction'.)

If no difficulty with airway management is anticipated, a rapid sequence induction and intubation (RSII) is indicated. (See 'Airway management' above and "Rapid sequence induction and intubation (RSII) for anesthesia".)

Either etomidate or ketamine is typically selected as the primary induction agent for a hemodynamically unstable patient. A 2019 systematic review noted no differences in outcomes (mortality, length of hospital stay, or number of blood transfusions) when ketamine (n = 634) rather than etomidate (n = 699) was selected to induce anesthesia in trauma patients (one randomized trial and two nonrandomized trials) [71]. Doses of induction agents are reduced if decreased blood pressure (BP) and/or increased heart rate (HR) indicate shock. The shock index (HR/systolic BP)is another composite measure that can be used to guide induction drug dosing; the higher the shock index the greater the recommended dosing reduction. A rising shock index (>0.9) has been consistently associated with blood loss when compared to use of systolic BP or HR alone and is also predictive of the need for massive transfusion [72,73]. (See "General anesthesia: Intravenous induction agents", section on 'Etomidate' and "General anesthesia: Intravenous induction agents", section on 'Ketamine'.)

Propofol is generally avoided since administration of an IV bolus may further reduce BP by causing dose-dependent venous and arterial dilation and decreased contractility [70]. However, in a hemodynamically stable trauma patient, a reduced dose of propofol (eg, 0.5 mg/kg) may be administered. Adjuvant induction agents (eg, opioids, lidocaine, midazolam) are eliminated in hemodynamically unstable patients, or doses reduced if hemodynamic stability has been achieved (table 9). (See "Intraoperative management of shock in adults", section on 'Induction'.)

The optimal dose of succinylcholine as the neuromuscular blocking agent (NMBA) for RSII is from 1 to 2 mg/kg IV [74]. Succinylcholine may be administered intramuscularly at 3 to 4 mg/kg if IV access is not available (table 10). Rocuronium 1.2 mg/kg IV was found to be noninferior to succinylcholine [75]. Dosing for RSII is discussed separately. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Neuromuscular blocking agents (NMBAs)'.)

Maintenance

Inhalation anesthetic agents

●Volatile inhalation agents – A volatile inhalation anesthetic agent is typically selected to maintain general anesthesia. Agents with a low blood-gas partition coefficient (eg, sevoflurane or desflurane) are preferred to permit rapid titration. Initially, the agent is administered at a lower concentration than in nontrauma patients due to dose-dependent cardiovascular effects of the volatile anesthetic agents. Subsequently, the agent is carefully titrated to maintain adequate anesthetic depth while avoiding hypotension that may further decrease end-organ perfusion. If systolic BP improves to ≥90 mmHg, the selected volatile agent may be increased to ≥0.5 minimum alveolar concentration (MAC) (table 11). Maintenance of anesthesia at 0.7 MAC is associated with a very low risk of explicit recall [76-78]. Brain monitoring such as processed EEG monitors (eg, BIS) may improve clinical ability to ensure unconsciousness. (See "Accidental awareness during general anesthesia", section on 'Brain monitoring'.)

In patients with multiple traumatic injuries that may include brain injury, the volatile agent is maintained ≤1 MAC to avoid dose-dependent increases in cerebral blood flow (CBF) and intracranial pressure (ICP). (See "Anesthesia for patients with acute traumatic brain injury", section on 'Our strategy'.)

Although volatile inhalation anesthetics are effective modulators of the inflammatory response after tissue injury and may have beneficial effects on organ function in humans and animal models, their clinical impact is uncertain as most studies have focused on ischemia-reperfusion injury and biomarkers of organ dysfunction rather than on meaningful clinical outcomes [79-86].

●Nitrous oxide (N₂O) gas – We generally avoid N₂O in trauma patients for several reasons [87-89] (see "Inhalation anesthetic agents: Clinical effects and uses", section on 'Nitrous oxide'):

•N₂O expands all gas spaces and can worsen a traumatic pneumothorax or pneumocephalus.

•In patients with traumatic brain injury (TBI), N₂O may increase the regional cerebral metabolic rate of O₂ (CMRO₂) consumption, and may also increase ICP [90,91].

•N₂O increases pulmonary vascular resistance and may worsen pulmonary hypertension [92].

•N₂O may cause apoptosis and altered immunologic responses to infection [89,93-95].

Administration of high-dose opioids — When systolic BP can be consistently maintained ≥90 mmHg and surgical hemostasis has been assured, many centers introduce gradually increasing doses of fentanyl during the maintenance phase of anesthesia, particularly if the patient will remain intubated and sedated with controlled ventilation in the immediate postoperative period. When systolic BP can be consistently maintained ≥90 mmHg and surgical hemostasis has been assured, we titrate opioids for analgesia, to blunt additional sympathomimetic surge, and to potentially dilate the microcirculation. Typically, we administer fentanyl in 50 to 150 mcg increments to a total dose of 10 to 30 mcg/kg. Fentanyl may cause beneficial dilation of the microcirculation and has minimal myocardial depressant effects [96-98]. In one post hoc analysis of 526 severely injured trauma patients, those who received intraoperative opioids in various doses had a lower incidence of mortality at 6 hours (odds ratios 0.02-0.04, 95% CI 0.003-0.1), at 24 hours (odds ratios 0.01-0.03, 95% CI 0.003-0.09), and at 30 days (odds ratios 0.04-0.08, 95% CI 0.01-0.18) compared with those who received no opioids [99].

Strategies to minimize risk of awareness — Some hemodynamically unstable trauma patients are at risk for intraoperative awareness since it may be unsafe to administer sufficient anesthesia to ensure lack of awareness during all phases of damage control surgery and other interventions. (See "Accidental awareness during general anesthesia", section on 'Surgery-related risk factors'.)

For this reason, during periods of suspected light anesthetic depth, we administer incremental doses of one or more adjuvant agents to potentially limit the traumatic effect of intraoperative awareness with postoperative recall, particularly if hemodynamic instability limits use of a volatile anesthetic agent [100]. Typically, we select a benzodiazepine (eg, midazolam 1 to 4 mg or diazepam 2 to 10 mg) to facilitate amnesia [101]. Brain monitoring such as processed EEG monitors (eg, BIS) may improve clinical ability to ensure unconsciousness [102]. (See "Accidental awareness during general anesthesia", section on 'Administration of adjuvant medications' and "Accidental awareness during general anesthesia", section on 'Brain monitoring'.)

If high-dose opioids have not been previously administered, we also give an opioid to decrease pain. (See 'Administration of high-dose opioids' above.)

Lung-protective ventilation — An intraoperative lung-protective strategy is used during controlled ventilation for patients with trauma and shock, with tidal volumes of 6 to 8 mL/kg. Mild permissive hypercapnia with partial pressure of carbon dioxide (PaCO₂) of 40 to 45 mmHg is allowed, unless the patient has metabolic acidosis or known or suspected TBI. In such cases, a faster respiratory rate may be temporarily employed to achieve an increased minute ventilation with a PaCO₂ of 30 to 35 mmHg. (See "Mechanical ventilation during anesthesia in adults", section on 'Lung protective ventilation during anesthesia' and "Anesthesia for patients with acute traumatic brain injury", section on 'Intraoperative ventilation and oxygenation'.)

Initial positive end-expiratory pressure (PEEP) is set at 0 cm H₂O until hemodynamic stability and control of hemorrhage and adequate resuscitation has been achieved. Subsequently, PEEP may be slowly and incrementally increased to 5 to 10 cm H₂O if tolerated without provoking hypotension, and fraction of inspired oxygen (FiO₂) is concurrently weaned to maintain arterial saturation >92 percent. The goal is to provide an optimal balance between minimizing lung injury while preventing hemodynamic instability. In patients with hemorrhagic shock, it is particularly important to avoid high levels of PEEP and dynamic hyperinflation with development of auto-PEEP [103]. PEEP and auto-PEEP increase intrathoracic pressure, and decrease venous return, cardiac output, and systemic BP. (See "Clinical and physiologic complications of mechanical ventilation: Overview", section on 'Hypotension'.)

We recommend peripheral arterial oxygen saturation (SpO₂) in the range of >92 percent but <98 percent [104-107]. We avoid hyperoxemia by continuously monitoring pulse oximetry and intermittently obtaining arterial blood gases to check the partial pressure of arterial oxygen (PaO₂) [108,109]. Our target values are an arterial oxygen saturation SpO₂ >92 percent or a PaO₂ >65 mmHg. Systematic reviews have found that liberal oxygen therapy resulting in hyperoxemia is associated with increased mortality in acutely ill patients with TBI, recent cardiac arrest, or stroke [104,105,108,110,111]. There is limited evidence suggesting benefits of a high FiO₂ in trauma patients, and no evidence for those with spontaneous respirations [112], Nevertheless, many trauma patients treated with supplemental oxygen will develop hyperoxemia [113].

Temperature management — Ongoing intraoperative resuscitation includes reestablishing and maintaining normothermia (temperature ≥36°C). Equipment to warm blood and IV fluids and devices to warm the patient should be used. The OR itself is kept warm to reduce the development or exacerbation of hypothermia. Details are discussed separately. (See "Perioperative temperature management".)

POSTOPERATIVE CONSIDERATIONS — After emergency trauma surgery, most patients remain intubated and sedated with controlled ventilation (see 'Administration of high-dose opioids' above). The anesthesiologist should continuously monitor the ECG, pulse oximetry (SpO₂), and intra-arterial blood pressure (BP) during transport to the intensive care unit (ICU) [114]. (See "Transport of surgical patients", section on 'Considerations for critically ill patients'.)

Upon arrival in the ICU, a clear, simple, and organized handoff is critically important (table 12). (See "Handoffs of surgical patients", section on 'Operating room to intensive care unit'.)

Reassessment of the extent of unresolved shock is necessary shortly after arrival in the ICU. In addition to providing controlled ventilation and hemodynamic support, many severely injured trauma patients require correction of critical acid-base and electrolyte abnormalities, restoration of normothermia, and/or efforts to minimize secondary central nervous system injury. Frequent postoperative reassessments for the possibility of missed injuries or inadequately treated pain are important after surgery in the traumatically injured patient. (See "Overview of inpatient management of the adult trauma patient", section on 'Consider other potential injuries'.)

SPECIAL POPULATIONS — Unique anesthetic considerations exist for certain injury-specific or patient–specific situations.

Resuscitative endovascular balloon occlusion of the aorta — In selected patients (eg, those with noncompressible torso hemorrhage following traumatic injury), resuscitative endovascular balloon occlusion of the aorta (REBOA) is a temporizing measure to support vital organ perfusion, decrease the amount of bleeding distal to the occluded site, and provide a window of opportunity for resuscitation and definitive hemorrhage control (figure 6) [115-118]. However, REBOA does not provide definitive hemorrhage control. REBOA indications and techniques are discussed separately. (See "Endovascular methods for aortic control in trauma".)

Anesthetic management during REBOA includes insertion of an separate intra-arterial catheter and a central venous catheter (CVC) for monitoring [119] (see 'Intravascular access and monitoring' above). The intra-arterial catheter must be placed in an upper extremity since perfusion to the lower extremity arteries will be temporarily interrupted during balloon occlusion of the aorta. Similar to intraoperative monitoring during endovascular aortic repair, transesophageal echocardiography (TEE) is particularly useful to assess changes in regional and global ventricular function, as well as intravascular volume status before, during, and after balloon occlusion [116,120]. TEE can also be used to guide positioning of the endovascular balloon [115,117].

During REBOA, critical hemodynamic changes occur with balloon inflation and deflation [115,116,120]:

●Inflation – Similar to application of an aortic crossclamp during abdominal aortic aneurysm (AAA) repair, proximal aortic occlusion during REBOA increases systemic vascular resistance (SVR), blood pressure (BP), and cardiac afterload, thereby increasing cerebral and myocardial perfusion (figure 6) [116,117,120]. Physiologically, the increased afterload, while supporting coronary perfusion, may also increase myocardial transmural wall tension and cardiac pressure work (figure 7) [117,121,122]. If systolic BP is higher than desired during proximal aortic occlusion, a reasonable strategy is to carefully increase volatile inhalation anesthetic concentration to produce some degree of vasodilation. (See "Anesthesia for open abdominal aortic surgery", section on 'Management of aortic cross-clamping' and "Endovascular methods for aortic control in trauma", section on 'Inflate the balloon catheter'.)

●Deflation – REBOA balloon deflation is attempted when hemostasis has been achieved or to check for sources of ongoing hemorrhage [115,117,120]. Similar to aortic unclamping during open AAA repair, deflation of the intra-aortic balloon catheter may result in severe hypotension due to sudden decreases in SVR, preload (due to venodilation and hypoxia-mediated reactive hyperemia), and myocardial contractility (due to metabolic [lactic] acidosis) (figure 8) [115,120,122,123]. Release of metabolites from ischemic muscle and other organ tissue and concomitant metabolic acidosis may also result in hyperkalemia, malignant arrhythmias, and cardiac arrest. (See "Anesthesia for open abdominal aortic surgery", section on 'Management of aortic unclamping'.)

Clear team communication is required in preparation for deflation [115,116,120]. In some cases, the surgeon must transiently, partially, or gradually deflate the balloon to prevent precipitous cardiovascular collapse that can occur after full balloon deflation. These maneuvers permit reperfusion between balloon occlusion periods, and allow the anesthesiologist to increase intravascular volume and add vasopressor and/or inotropic agents if necessary. (See "Endovascular methods for aortic control in trauma", section on 'Duration of inflation and balloon deflation'.)

Following balloon deflation, metabolic derangements (eg, hypercarbia, acidosis, hyperkalemia, anemia, disorders of hemostasis) may persist, similar to reperfusion after aortic surgery [115,116,120,123]. In addition to obtaining standard point-of-care (POC) laboratory tests, serum lactate levels are monitored to assess reversal of shock as intraoperative resuscitation is completed [60,124]. (See "Anesthesia for open abdominal aortic surgery", section on 'Point-of-care testing'.)

Acute traumatic brain injury — Anesthesia for patients with acute traumatic brain injury (TBI) is discussed separately (table 13). (See "Anesthesia for patients with acute traumatic brain injury".)

Acute traumatic spinal cord injury — Anesthesia for acute spinal cord is discussed separately. (See "Anesthesia for adults with acute spinal cord injury" and "Acute traumatic spinal cord injury".)

Orthopedic trauma — Anesthesia for orthopedic trauma is discussed in a separate topic. (See "Anesthesia for orthopedic trauma".)

Thoracic trauma — Injuries to the heart and lungs, along with their connecting structures, have many nuances in anesthetic management, as discussed in a separate topic. (See "Anesthesia for thoracic trauma in adults".)

Burn injury — Anesthesia for burn-injured patients is discussed elsewhere. (See "Overview of the management of the severely burned patient" and "Anesthesia for patients with acute burn injuries".)

Traumatic injury in pregnant patients — Specific considerations for airway management, uterine displacement , volume replacement and transfusion, use of vasopressors, and decisions regarding cesarean delivery are discussed in a separate topic [125]. (See "Initial evaluation and management of major trauma in pregnancy".)

Other considerations for anesthetic management of pregnant patients undergoing nonobstetric surgery are discussed separately. (See "Anesthesia for nonobstetric surgery during pregnancy".)

Geriatric trauma — Management of older adult trauma victims is discussed elsewhere. (See "Geriatric trauma: Initial evaluation and management" and "Anesthesia for the older adult".)

Substance use disorder or acute intoxication — Acute intoxication is frequently associated with trauma; some patients may be impaired with multiple intoxicants. Anesthetic management is discussed in a separate topic. (See "Anesthesia for patients with substance use disorder or acute intoxication".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Transfusion and patient blood management" and "Society guideline links: Thoracic trauma" and "Society guideline links: Airway management in adults" and "Society guideline links: Traumatic abdominal and non-genitourinary retroperitoneal injury" and "Society guideline links: Use of point-of-care echocardiography and ultrasonography as a monitor for therapeutic intervention in critically ill patients".)

SUMMARY AND RECOMMENDATIONS

●Patient stabilization and goals – Specific goals during stabilization of trauma patients in the emergency department (ED) and the operating room (OR) include (see 'Patient stabilization and goals' above):

•Airway management – A clearly defined, sequential approach to a patient with airway injury or abnormality is critical, since delay in securing the airway may lead to rapidly progressing hypoxemia (algorithm 1). The tables address management of specific injuries such as airway disruption (table 2), oral or maxillofacial trauma (table 3), neck compression (table 4), closed head injury (table 5), or possible spinal cord injury (figure 1). (See 'Airway management' above.)

•Intravascular access and monitoring – An intra-arterial catheter and a central venous catheter (CVC) are usually inserted in hemodynamically unstable patients. Large-bore peripheral intravenous catheters may be used instead of or in addition to a CVC. (See 'Intravascular access and monitoring' above.)

•Intraoperative management of hemorrhagic shock – Our approach to managing hemorrhagic shock focuses on limiting crystalloids, administering blood products to maintain adequate hemoglobin targets, and managing coagulopathy. Although the transfusion target is a hemoglobin of 7 to 8 g/dL, immediate life-saving transfusion may be necessary before laboratory assessment of hemoglobin is available when blood loss is rapid and significant. Also, intraoperative blood salvage is often employed. Details are presented in separate topics. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient" and "Approach to shock in the adult trauma patient".)

•Point-of-care (POC) and standard laboratory testing – In addition to monitoring hemoglobin, standard laboratory coagulation tests and POC viscoelastic tests (eg, thromboelastography [TEG], thromboelastometry) are typically employed to allow rapid assessment of causes of coagulopathy and responses to transfusion. Assessment and treatment of electrolyte abnormalities, elevated serum lactate level, and acid-base derangements are also necessary. (See 'Point-of-care and standard laboratory testing' above.)

•Hemodynamic management – Strategies to limit ongoing blood loss include maintenance of a low to normal systolic blood pressure (BP) at approximately 90 mmHg (or ≤110 mmHg in older adults) and/or mean arterial pressure (MAP) at 50 to 65 mmHg. Once hemostasis has been achieved, higher BP values are targeted (eg, systolic BP ≥90 mmHg and/or MAP ≥65 mmHg). Vasopressor use in hemorrhagic shock is not a first-line treatment. (See "Intraoperative management of shock in adults".)

●Management of general anesthesia

•Induction – If no difficulty with airway management is anticipated, a rapid sequence induction and intubation (RSII) with either etomidate or ketamine is typically employed; propofol is avoided in hypotensive patients (table 14). (See 'Induction' above.)

•Maintenance

-Inhalation anesthetic agents – We typically employ a volatile inhalation anesthetic agent (eg, sevoflurane) for maintenance of anesthesia, initially administered at a lower concentration than in nontrauma patients and carefully titrated to clinical effect. We generally avoid nitrous oxide. (See 'Inhalation anesthetic agents' above.)

-High-dose opioids – When systolic BP can be consistently maintained ≥90 mmHg and surgical hemostasis has been assured, we titrate opioids for analgesia, to blunt additional sympathomimetic surge, and to potentially dilate the microcirculation (typically, fentanyl in 50 to 150 mcg increments to a total dose of 10 to 30 mcg/kg). (See 'Administration of high-dose opioids' above.)

-Prevention of awareness – During periods of light anesthetic depth, we also administer incremental doses of one or more adjuvant agents to minimize risk of awareness. (See 'Strategies to minimize risk of awareness' above.)

•Lung-protective ventilation – An intraoperative lung-protective strategy is used during controlled ventilation, but initial positive end-expiratory pressure (PEEP) are set at 0 cm H₂O with incremental increases to 5 to 10 cm H₂O. We avoid hyperoxemia. (See 'Lung-protective ventilation' above.)

•Maintenance of normothermia – We maintain temperature ≥36°C. (See 'Temperature management' above.)

●Postoperative considerations – Most severely injured patients remain intubated and sedated with controlled ventilation. Upon arrival in the intensive care unit, a clear, simple, and organized handoff is ensured (table 12). (See 'Postoperative considerations' above.)

●Special populations – Injury-specific or patient–specific situations with additional considerations are discussed in separate topics:

•(See 'Resuscitative endovascular balloon occlusion of the aorta' above.) and (figure 6 and figure 7 and figure 8)

•(See "Anesthesia for patients with acute traumatic brain injury".)

•(See "Anesthesia for adults with acute spinal cord injury" and "Acute traumatic spinal cord injury".)

•(See "Anesthesia for orthopedic trauma".)

•(See "Anesthesia for thoracic trauma in adults".)

•(See "Anesthesia for patients with acute burn injuries".)

•(See 'Traumatic injury in pregnant patients' above.)

•(See "Geriatric trauma: Initial evaluation and management" and "Anesthesia for the older adult".)

•(See "Anesthesia for patients with substance use disorder or acute intoxication".)