Vehicular trauma is a common presentation in the veterinary emergency clinic and the most common type of blunt force trauma in dogs and cats.1,2 Management of vehicular trauma cases can be complex and require advanced resources and care. In humans, trauma-related deaths typically occur in the hospital within 48 hours due to exsanguination or CNS injuries.3 In dogs, risk factors for nonsurvival following blunt trauma include uncontrolled hemorrhage, severe neurologic injury, recumbency on initial evaluation, development of multiple organ dysfunction syndrome or acute respiratory distress syndrome, need for mechanical ventilation, and hematochezia.4 This article reviews initial stabilization measures that can be performed in a general practice clinic before referral to a tertiary facility.
Traumatic injuries can result in a variety of abnormalities, with clinical signs ranging from apparent pain, fractures, hemorrhage, and superficial lacerations to systemic inflammatory response syndrome, multiple organ dysfunction syndrome, and death. Although many of these signs can be sequelae of vehicular trauma, immediate resuscitation efforts should focus on minimizing ongoing inflammation, hemorrhage, and tissue hypoperfusion (and, subsequently, morbidity and mortality) through an approach known as damage control resuscitation.1 Damage control resuscitation incorporates early and balanced administration of blood products (1:1 ratio of fresh frozen plasma [FFP] and packed RBCs [pRBCs]), hemorrhage control, and judicious use of balanced crystalloids.1
Initial evaluation should be rapid and systematic to allow timely initiation of stabilization treatments. Complications that are most likely to be life threatening should be assessed first in order of body systems, which can be remembered with help of the mnemonic XABCD (see Initial Evaluation of Patients With Blunt Trauma).
Initial Evaluation of Patients With Blunt Trauma
Complications should be addressed simultaneously, starting with external bleeding.
X - Exposure: external bleeding
Life-threatening external bleeding should be addressed immediately.
AB - Respiratory (airway and breathing): decreased or increased lung sounds, dyspnea, tachypnea, stridor, upper airway sounds, cyanosis, or apnea
Abnormal breathing patterns should be assumed to have primary respiratory causes (eg, pleural space or pulmonary parenchymal disease) unless proven otherwise.
C - Cardiovascular: perfusion abnormalities resulting in pale pink mucous membranes, prolonged capillary refill time, weak pulses, hypothermia, altered mentation, tachycardia, or bradycardia
Poor perfusion should be an assumed result of hemorrhage (vs other types of shock) unless proven otherwise.
D - CNS (disability): level of consciousness, pupil size and reactivity, paresis/paralysis, seizure activity, or cranial nerve deficits
Rapid assessment and resuscitation are essential for maximizing the likelihood of survival. Early death, predominantly from hemorrhage, may be preventable.
Step-by-Step: Stabilization Following Vehicular Trauma Prior to Tertiary Referral
What You Will Need
Oxygen therapy (eg, flow-by)
IV catheter
IV fluids (isotonic crystalloids or hypertonic saline preferred)
Blood products (FFP, pRBCs), if available
Analgesics
ECG and blood pressure monitoring equipment
Step 1: Provide Oxygen
At presentation, provide supplemental oxygen, especially to patients with signs of respiratory distress, thoracic injury, or traumatic brain injury.
Author Insight
Oxygen can be provided via flow-by, oxygen cage, or intubation if necessary. Minimizing stress is essential. The decision of whether to place a nasal cannula should thus be based on the needs of the patient.
Step 2: Place an IV Catheter
Place the widest bore, shortest length IV catheter possible to maximize efficiency while delivering fluid boluses.
Author Insight
The catheter can be placed while oxygen is supplemented via flow-by.
If peripheral venous access is not obtainable, jugular venous access may be attempted, but caution is needed in patients with suspected traumatic brain injury, as jugular access may impede venous return from the brain, exacerbating intracranial hypertension. A cutdown or intraosseous catheter may be considered in patients with periarrest or cardiopulmonary arrest.
Step 3: Administer Fluids
Administer appropriate fluid therapy for resuscitation.
Author Insight
Low-volume fluid resuscitation is optimal for administering crystalloid fluid therapy in trauma care. Low-volume crystalloid therapy, a component of damage control resuscitation, can restore tissue hypoperfusion while minimizing dilution of coagulation factors and RBCs (thus minimizing increases in blood pressure that can dislodge formed clots) and reduce hypothermia, which can improve clotting mechanisms. Conservative balanced crystalloid fluid (isotonic crystalloids, 10-15 mL/kg over 10-15 minutes) administration may therefore be considered first-line therapy in patients presented with shock.
Hypertonic saline (7.5% hypertonic saline, 3-7 mL/kg over 10-15 minutes5,6) administration for low-volume fluid resuscitation may also be considered first-line therapy in patients with shock, as it can improve blood flow and cardiovascular function, reduce edema and endothelial swelling, exert positive immunomodulatory effects, and help treat traumatic brain injury; however, it can increase mean arterial pressure, resulting in further hemorrhage in patients with noncompressible bleeding.7,8 Hypertonic saline is indicated in trauma patients that are not severely dehydrated or hypernatremic (both of which are uncommon in trauma patients) and are receiving fluid resuscitation without blood products.
Blood Pressure in Patients With Trauma
Systolic blood pressure of 80 to 90 mm Hg or mean arterial pressure of 50 to 60 mm Hg should be targeted in trauma patients with hemorrhage to achieve oxygen delivery to tissues while avoiding further hemorrhage by allowing thrombus formation (permissive hypotension). Increasing blood pressure through resuscitation is generally easier than reducing blood pressure in a normotensive or hypertensive trauma patient. Reducing blood pressure to a systolic pressure of 80 to 90 mm Hg (mean arterial pressure, 50-60 mm Hg) in a hypertensive or normotensive patient is not always possible, although permissive hypotension can often be accomplished via administration of analgesics. Brief periods (60-90 minutes) of permissive hypotension do not significantly increase the risk for mortality but can progress to end-organ damage and death if left untreated.17 Patients with traumatic brain injury, however, must be resuscitated to a systolic blood pressure of >90 to 100 mm Hg to support perfusion to the brain, as hypotension is an independent risk factor for mortality in humans with traumatic brain injury.18,19
Step 4: Administer Blood Products
If available, administer blood products as appropriate.
Author Insight
Early intervention with blood products should be considered for treatment of hemorrhagic shock; however, this may not be possible in a general practice clinic and is not necessary for initial stabilization prior to referral. Hemostatic resuscitation involves administration of a 1:1 ratio of pRBCs and FFP.9 FFP and pRBC dosages range from 10 to 20 mL/kg over 2 to 4 hours in stable patients but can be administered as a bolus in patients decompensating due to hemorrhagic shock.
Step 5: Administer Antifibrinolytic Therapy
If available, administer antifibrinolytics as needed to improve clot strength.
Author Insight
Acute traumatic coagulopathy as a result of severe inflammation, bleeding, and/or iatrogenic causes (eg, dilutional coagulopathy, hypothermia) is an established principle in human trauma patients. Hyperfibrinolysis is a characteristic sign of acute traumatic coagulopathy, and antifibrinolytics can increase likelihood of survival in humans.10 Acute traumatic coagulopathy has been reported in veterinary patients, and antifibrinolytics can improve clot strength.11-13 Dogs can be given tranexamic acid (TXA; 20 mg/kg IV every 6 to 8 hours) or aminocaproic acid (ACA; 33 mg/kg IV every 6 hours) until bleeding is controlled.14 In cats, doses for TXA (10 mg/kg) and ACA (50 mg/kg) have been reported but are not established.15,16 Antifibrinolytic therapy may not be possibile in a general practice clinic and is not essential for initial stabilization.
Step 6: Administer Analgesics
Administer medication for treatment of acute pain.
Author Insight
Full mu-receptor agonists (eg, methadone, fentanyl, hydromorphone; see Table) are ideal for treatment of acute pain associated with trauma because of their efficacy and safety. Buprenorphine can be used for mild to moderate pain, but butorphanol should be avoided due to its minimal analgesic effects.
Table: Mu-Receptor Agonist Dosages for Acute Pain
Conclusion
The interventions (eg, oxygen, fluids, pain medication) outlined in this article are available in most clinics. Emergency stabilization and resuscitation of patients with vehicular trauma require rapid and thorough evaluation, as well as careful treatment of tissue hypoperfusion without exacerbation of ongoing hemorrhage and shock. Swift optimization of tissue perfusion with close monitoring is crucial for maximizing good outcomes prior to tertiary referral.
Listen to the Podcast
Dr. Blutinger gives a thorough review of the approach to trauma cases—emphasizing management of hemorrhages—and the steps we can take to stabilize these patients.