Trauma Anesthesia

Objectives

• The objectives are to describe trauma epidemiology.
• Objectives involve outlining the elements of the initial trauma assessment and secondary survey.
• Objectives include prioritizing unique considerations for airway management, cervical spine precautions, circulatory collapse, fluid resuscitation, and blood product administration.
• Objectives involve formulating a peri-operative anesthetic plan for various types of trauma patients.
• Objectives include recognizing post-operative complications including acute renal failure, abdominal compartment syndrome, and thromboembolism.

Background

• Trauma accounts for 9% of total annual mortality worldwide.
• There are 1.24 million traffic accident fatalities, the largest proportion being pedestrians, cyclists, and motorcyclists.
• 1.5 million deaths are related to violence including homicide, suicide, and war-related incidents.
• There are disproportionate trauma fatalities in low and middle income countries.
• High-energy mechanisms of injury have the highest proportion of deaths in the first 48 hours; 1/3 of these patients die in the first 4 hours.
• Low-energy impact death rates are higher after 7 days.
• Head trauma is the leading cause of mortality (40%); the second leading cause is hemorrhagic shock.
• 2-4% of blunt traumas have concurrent C-spine injuries.

Pathophysiology Hemorrhagic Shock

• An imbalance occurs between systemic O2 delivery and consumption.
• Hemorrhagic shock causes hemodynamic instability, coagulopathy, decreased O2 delivery, decreased tissue perfusion, and cellular hypoxia.
• The initial response is macrocirculatory and mediated by the neuroendocrine system.
• Renin, angiotensin, vasopressin, antidiuretic hormone, growth hormone, glucagon, cortisol, epinephrine, and norepinephrine are released.
• The initial response sets the stage for the microcirculatory response.

Organ Response to Hemorrhagic Shock

• The CNS is the prime trigger of the neuroendocrine response and controls selective perfusion to the heart, kidney, and brain.
• Reflexes and cortical electrical activity are both depressed, but reversible with mild hypoperfusion.
• The heart is preserved from ischemia.
• Lactate, free radicals, and other humoral factors released by ischemic cells all act as negative inotropes.
• Cardiac dysfunction is a LATE SIGN and often a terminal event.
• The pulmonary system filters the inflammatory byproducts of ischemia.
• The renal/adrenal system is part of the neuroendocrine response; GFR is maintained with selective vasoconstriction.
• The gut is one of the earliest organs affected by hypoperfusion and may be the prime trigger of MSOF.
• Liver failure of synthetic function after shock can be lethal.
• Skeletal muscles release lactic acid and free radicals while tolerating ischemia better than other organs.

Assessment

• Assessment begins with an initial rapid assessment: stable vs. unstable.
• Primary Survey: ABCDE (airway, breathing, circulation, disability, exposure) are assessed.
• First, is ABCs of airway patency, breathing, and circulation.
• Second, is a brief neurologic examination (D).
• Undress and inspect (ventrally and dorsally) for external injuries that were overlooked (E).
• A decision will be made to proceed immediately to surgery or continue on to secondary survey.
• Secondary survey: a detailed multi-system exam and history and further diagnostic evaluation.

Airway Management

• Anesthesia is responsible for initial airway assessment and management on arrival.
• Evaluate the need for mask ventilation, intubation, or surgical airway.
• Assess the needs for imminently preparing the OR and planning anesthetic management, like obtaining a rapid infuser, special drugs, lines, and blood products.
• Stabilize the C-spine before airway management.
• Provide oxygen (100% until ABG).
• Start with initial steps for obstruction: chin lift, jaw thrust, suction, place OPA or NPA (+/-).
• If still inadequate, consider BMV to assist spontaneous breathing.
• Consider SGA (short term).
• Proceed to intubation: consider awake vs. RSI vs. cricothyroidotomy.

Cervical Spine Precautions

• Cervical spine injuries can be missed on initial trauma assessment.
• CT or MDCT (<3mm cuts) is a typical diagnostic tool, but soft tissue/ligamentous injuries cannot be seen.
• MRI is gold-standard to reliably rule out C-spine injury.
• Airway management related cervical cord injury is exceptionally rare, but precautions are mandatory.
• All airway maneuvers cause c-spine movement.
• A rigid collar is not enough.
• Manual inline stabilization (MILS) is preferred.
• Exercise caution: unopposed vagal tone during airway manipulation.
• Preoxygenate and premedicate to avoid complications.
• Optimally, two people are needed in addition to anesthesia provider for MILS.
• The first assistant stabilizes and aligns the head in a neutral position without applying cephalad traction.
• The second person stabilizes both shoulders by holding them against the table or stretcher.
• The anterior portion of the hard collar may be removed after immobilization to improve mouth opening.
• MILS can obstruct the glottic view.

Blunt & Penetrating Airway Injuries

• Blunt symptoms include hoarseness, muffled voice, dyspnea, stridor, dysphagia, odynophagia, cervical pain and tenderness, ecchymosis, subcutaneous emphysema, and flattening of the Adam's apple.
• DL can worsen and may enter a false passage.
• A CT scan is needed before airway intervention if the patient is stable.
• Preferred airway management is FOB or surgical airway.
• 70% of blunt airway injuries also have C-spine injuries.
• Blunt airway injuries can be missed.
• Penetrating airway injury symptoms include air bubbling through the wound, hemoptysis, and coughing.
• Management varies: ETT is inserted in the wound, tracheostomy distal to the wound, or oral intubation.

Pulmonary Complications

• Tension pneumothorax can occur.
• There is no time for X-ray/ CT to confirm a tension pneumothorax.
• Treatment involves needle decompression vs. chest tube.
• Flail chest involves two or more sites on at least three adjacent ribs.
• Rib fractures may be associated with costochondral separation or sternal fracture.
• Open pneumothorax requires caution due to vascular air entrainment.

Shock

• Definitive treatment: operative control of bleeding at source.
• Expect major bleeding: from Falls >6 feet, high energy deceleration injury, and high velocity GSW.
• Free fluid on X-ray, FAST, or CT warrants immediate intervention.
• The ideal SBP is 100-110mmHg.
• Follow lactate and base deficit values.
• Intraop endpoints of resuscitation should be monitored.
• Goal hgb 7-9g/dL.

Damage Control Principles

• 1st phase (arrival): recognition of severity of injury, control of bleeding, and rapid transport to the OR.
• Limit crystalloids, permissive hypotension, activating rewarming, and early administration of FFP and platelets at high ratios with PRBCs.
• 2nd phase (in OR): surgeons rapidly control bleeding and leave abdominal cavity open.
• Maintain intravascular volume, temperature, acid-base status, and coagulation.
• 3rd phase: ICU management with the same goals as in the OR.
• 4th phase: multiple returns to the OR at 24- to 48-hour intervals for organ repair, abdominal washout, and debridement.

Fluid Resuscitation

• Damage control: includes brief permissive hypotension and rapid control of any bleeding source- abbreviated surgery.
• AVOID large volume crystalloid infusion.
• Early administration of plasma and other blood products in a balanced ratio, preferably 1:1:1 of packed red blood cells (PRBCs), plasma, and platelets
• Tranexamic acid can be considered (+/-).
• New PRBC's are preferred (<14 days old).
• No crossmatch and severe hemorrhage: use O Rh-positive PRBCs and AB-negative FFP.

Traumatic Brain Injury; Open Globe

• The primary goal is to prevent secondary injury.
• Avoid: hypotension, hypoxemia, anemia, raised ICP, acidosis, & glucose >200 mg/dL.
• Normalize bp (mean >80 mmHg), PaO2 >95, ICP <20 to 25 mmHg, & CPP at 50-70 mmHg.
• General management: HOB 30 degrees, sedation & paralysis PRN, NS preferred over LR; mannitol & hypertonic Na+ PRN.
• Smooth/ rapid intubation is needed; avoid desaturation.
• Hyperventilation: wait 24 hours after injury; only for short periods; only as emergency intervention when osmotic agents ineffective; guided by ICP monitoring.
• Avoid hypoxia, hypercarbia, and hyperthermia.

Spinal Cord Trauma

• Incomplete vs. complete injuries exist.
• The actual level of injury can be several segments below the area of symptoms.
• Injury level cannot be differentiated at admission.
• Spinal shock: flaccidity and loss of reflexes.
• Spinal shock subsides days to weeks.
• C4 & above injuries require a ventilator.
• Partial cord transection is known as Brown-Séquard syndrome.

Blunt Cardiac Injury

• Monitor with ECG, and if abnormal, consider ICU monitoring.

Pericardial Tamponade

• Symptoms include tachycardia, hypotension, distant heart sounds, distended neck veins, pulsus paradoxus, or pulsus alternans; these symptoms may be absent in a hypovolemic patient.
• Must maintain preload & contractility.
• Preferred to evacuate pericardial blood under local anesthesia.
• Induce with small doses of ketamine if necessary.
• Wait until prepped and draped to induce.

Abdominal Trauma

• Laparoscopy or laparotomy is required in most patients after a gunshot wound to the abdomen.
• FAST ultrasound vs. СТ can be performed for diagnosis.
• Occult bleeding can be massive before abdominal distention is appreciated.
• Unrecognized hypoperfusion can lead to splanchnic ischemia causing acidosis in the intestinal wall.
• Translocation of microorganisms & inflammatory mediators from intestines may occur.
• Abdominal trauma leads to sepsis and multi-organ failure.

Pelvic Injuries

• 25% of pelvic fractures lead to major hemorrhage.
• Arterial bleeding is treated with embolization.
• Bladder and urethral injuries may occur concurrently.

Orthopedic/ Soft Tissue Trauma

• Early repair reduces complications.
• Vascular injuries manifest as the P's: pain, pulselessness, pallor, paresthesias, and paresis.
• Compartment syndrome requires emergency fasciotomy.
• A pressure >30 cm of H2O needs immediate surgery.
• Caution with regional anesthesia as it can mask pain of compartment syndrome.

Vascular Access/ Hemodynamic Monitoring

• Minimum of two large bore IV's are needed and CVL may be indicated.
• A-line: Right radial artery is preferred.
• Consider PPV and SVV to guide fluid responsiveness.

• 12% likely a responder to fluid.

• Note the limitations of PPV and SVV.
• PA catheter is less common but may be indicated in some populations.
• TEE/ TTE yields qualitative & quantitative information.

Coagulopathy in Trauma

• Hemodilutional coagulopathies occur from fluid resuscitation.
• There is rapid consumption of clotting factors.
• Activation of Protein C inhibits clotting factors V and VIII and decreases the inhibition of TPA.
• Monitor INR, aPTT, platelets, fibrinogen, and fibrin degradation products (FDPs).
• TEG/ROTEM monitors clot formation & dissolution.
• FDP >40 mg/mL, is suggestive of DIC.

Blood Product Administration

• PRBC's that are "new blood" are preferred (<14 days old).
• Citrate is present in all blood products and chelates calcium.
• Hypocalcemia: defective coagulation plus hypotension, decreased pulse pressure, arrhythmias, change in mental status, and tetany.
• FFP contains all coagulation components.
• The PRBC: FFP ratio currently preferred is at 1:1 or 2:1.
• Platelets: infuse to goal >50k.
• Cryoprecipitate contains factor VIII, fibrinogen, von Willebrand factor, fibronectin, and factor XIII.
• It is used primarily to replace fibrinogen.

Anesthetic Pharmacology in Trauma

• Most anesthetics are direct CV depressants and inhibit compensatory reflexes.
• Hypovolemia leads to higher plasma concentrations and increased sensitivity to anesthetics.
• Dilutional hypoproteinemia leads to increased free fraction of drugs.
• Hypovolemia may be masked by catecholamine surge & revealed with administration of anesthetic.
• OVERALL: reduce administered doses of induction agents and opioids.
• Ketamine and Etomidate are frequent drugs of choice @ induction.
• Use caution with Ketamine in catecholamine depleted patients.
• MAC is reduced by ~25% in hemorrhagic shock.

Hypothermia

• Core temperature is < 35°C.
• Main effects: acidosis, hypotension, and coagulopathy.
• Cardiac depression & ischemia, arrhythmias, peripheral vasoconstriction, impaired tissue oxygen delivery, elevated oxygen consumption during rewarming, blunted response to catecholamines, increased blood viscosity, metabolic acidosis, electrolyte imbalance, reduced drug clearance, & infection.
• Coagulation factor function decreases ~10% for each 1°C drop in temperature.
• Aggressive rewarming is critical.

Ventilator Management

• Follow lung protective strategies.
• Ventilation should include: VT no more than 6 mL/kg, appropriate level of PEEP, the titration of FiO2 to lowest possible level, plateau airway pressures below 35 cm H2O, and the avoidance of auto-PEEP.

Miscellaneous Management

• Trauma has the highest rate of intraoperative death.
• Overlooked injuries can be revealed during anesthesia.
• Overlooked injuries can include c-spine injury, unrecognized thoracoabdominal injury during an extremity surgery, unrecognized pneumothorax.
• Monitor serial serum K+'s & treat hyperkalemia PRN.
• Correct the cause of metabolic acidosis rather than using liberal bicarbonate.
• Use bicarbonate only short term to prevent dysrhythmias when pH<7.2.
• Thromboembolism precautions are critical.
• Use SCD's and LMWH (if Benefit>Risk), and place IVC filter if unable to use prophylaxis

Late Resuscitation

• Begins once bleeding is definitively controlled.
• Driven by end-point targets.
• Traditional vital signs and markers include ABP, HR, and urine output, but there are no single definitive markers of adequate resuscitation.
• Maintain volume status, blood composition, and cardiac output.
• Look at all available data as a whole to determine need for continued resuscitation to prevent MSOF.

Late Resuscitation Goals

• Maintain systolic blood pressure higher than 100 mm Hg.
• Maintain hematocrit above individual transfusion threshold.
• Normalize coagulation status.
• Normalize electrolyte balance.
• Normalize body temperature.
• Restore normal urine output.
• Maximize cardiac output by invasive or noninvasive measurement.
• Reverse systemic acidosis.
• Document a decrease in lactate to the normal range.

Trauma in Pregnancy

• Can cause spontaneous abortion, preterm labor, or premature delivery.
• The best treatment is resuscitation of the mother.
• In 2nd/3rd trimester: get usg to determine fetal age, size, and viability; have fetal heart rate monitored continuously if fetus is at age of viability.
• Immediate cesarean section is needed if the mother is in extremis, uterus is hemorrhaging, or gravid uterus is impairing surgical control of abdominal or pelvic hemorrhage.
• Placental abruption is secondary to substance abuse or abdominal trauma, which can lead to uterine hemorrhage requiring an emergency cesarean section.
• Perform a Kleihauer-Betke blood test: has fetal blood entered mom's circulation?
• If yes, anti-Rh0 immune globulin is administered if Rh(-) mom is carrying Rh (+) fetus.
• In the 3rd trimester: aortocaval compression requires left uterine displacement.

Trauma in Elderly

• Elderly patients are more prone to morbidity.
• Decreased cardiopulmonary reserves are present, leading to a higher incidence of postoperative mechanical ventilation and a greater risk for multi-system organ failure after hemorrhagic shock.
• A higher hct is desired to optimize tissue oxygenation.
• High risk of post-traumatic cardiac dysfunction leads to monitoring of cardiac status (a-line, TEE, non-invasive hemodynamic monitors) to guide fluids/inotropes.
• Decreased requirement for postop opioids.
• Potential agitation/ delirium with sedatives.
• High risk DVT is possible due to immobilization.

Trauma in Jehovah's Witness

• Deliberate hypotension is an option.
• Early surgical control of bleeding is important.
• Patient may consent to cell salvaging if one continuous system is used.
• Use colloids (ask first), pressors, and inotropes to keep tissue O2 delivery optimized.
• Post-acute: consider erythropoietin to promote RBC regrowth.