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Trauma in Emergency Medicine in Animals

By

Andrew Linklater

, DVM, DACVECC, Lakeshore Veterinary Specialists, Glendale, Wisconsin;


Annie Chih

, DVM, DACVECC, Animal Medical Center of Seattle, Shoreline, WA

Last full review/revision Nov 2020 | Content last modified Nov 2020
Topic Resources

Diagnostic and therapeutic efforts in emergency situations are directed by the nature and severity of the trauma. Blunt trauma is commonly associated with thoracic and abdominal bleeding, organ rupture, fractures, and neurologic injuries. Penetrating trauma is typically localized to the path of the penetrating object, which is rarely a straight line. Falling from a height causes long bone and facial bone fractures as well as thoracic and abdominal injuries. A dog bitten by a larger dog can have deep-penetrating bite wounds, spinal injuries, major cervical, abdominal, and thoracic trauma (even without penetrating wounds), and tracheal rupture from the shearing forces sustained during thrashing motions. Resuscitation of the airway, breathing, and circulation; control of hemorrhage; and pain relief are followed by a careful evaluation of the nervous system, thorax, abdomen, integument, ocular, and musculoskeletal systems.

The traumatized animal should be approached as if multiple injuries are present. The neck and spine should be immobilized until a thorough examination for spinal fractures or luxations is made. Thoracic auscultation for cardiac arrhythmias and the presence and quality of lung sounds should be done to identify thoracic injuries. The abdomen and inguinal and rectal regions should be palpated for pain, fluid, or hernias. Extremity fractures should be supported by bandages or splinted to prevent further injury. Significant swelling may indicate ongoing hemorrhage. Because many internal injuries are not apparent for a significant amount of time after the initial trauma occurs (12–48 hours), close monitoring is essential to allow early detection of potentially life-threatening problems. An animal that appears normal and stable on initial examination may have substantial underlying injury, making monitoring of at least physical examination parameters in the hospital (eg, respiratory and heart rates, mucous membrane color, and mentation) appropriate.

Initial diagnostic evaluation should include the minimum database before fluids are administered, if possible. Point-of-care tests should minimally include a PCV, total solids, BUN test strip, and blood glucose.

When hemorrhage first occurs, the peripheral blood PCV may be normal or even increased, with a relative normal or decreased total protein level; this is a clinical indication of hemorrhagic shock in dogs; splenic contraction releases RBCs into circulation, maintaining PCV temporarily. Serial PCV and total solid measurements should be monitored after trauma; PCV and total solids both will decrease as hemorrhage and fluid resuscitation continues.

An extended initial database includes arterial or venous blood gases, electrolyte panel, blood lactate, and assessment of coagulation. This baseline information is used to create the initial treatment plan and to provide the baseline for subsequent monitoring. Radiographs of the thorax and abdomen at presentation can demonstrate the initial changes resulting from thoracic and abdominal trauma or may be useful to provide a baseline if normal. Orthogonal views should be performed as the animal's condition dictates. In addition to ultrasound, examination of the abdominal and thoracic cavities may provide more information about internal injuries and can often be performed while resuscitation is initiated.

Some scoring systems have been developed for trauma, such as the animal trauma triage score; this system assigns a number from 0 (slight or no injury) to 3 (severe injury) in the following categories: perfusion, cardiac, respiratory, eye-muscle-integument, skeletal, and neurologic. In one study assessing >200 dogs evaluated after vehicular trauma, dogs that died or were euthanized had significantly higher scores (median 6) than those that survived (median 2); higher scores were also associated with higher cost of care. The modified Glasgow coma score and the composite Glasgow pain scale are useful tools to monitor trauma patients. These scoring systems will help to objectively assess patients over time as well.

Several factors have been associated with a poorer outcome in trauma, including:

  • ionized hypercalcemia

  • hyperlactatemia

  • elevated BUN

  • increased animal trauma triage score

  • lower modified Glasgow coma score

  • low SpO2

  • serum pH

  • head trauma

  • development of a variety of organ disorders (pneumonia, need for pressors, DIC)

Hospitalizing a patient for observation provides a method of continual evaluation of vital signs (temperature, pulse, respiration, blood pressure), clinical pathology data (PCV, total solids, lactate, etc), neurologic injury, as well as observation of ability to ambulate, urinate, defecate, eat, and drink.

Thoracic Trauma

Some potentially life-threatening complications considered in thoracic trauma include:

  • pulmonary contusions

  • pneumothorax

  • cardiac arrhythmias

  • pleural hemorrhage

  • pericardial hemorrhage

  • rib fractures

  • flail chest

  • diaphragmatic hernia

Oxygen supplementation and analgesics allow for careful physical examination. An ECG, thoracic radiographs, or bedside ultrasound examination, arterial blood gas analysis, and diagnostic or therapeutic centesis can help to determine the extent and severity of the trauma.

Severe pulmonary contusions cause hypoxemia, labored breathing, and crackles or rales on pulmonary auscultation. If the animal does not improve with supplemental oxygen, pain medications, and fluid therapy, then tracheal intubation and positive-pressure ventilation with 100% oxygen are indicated. The airway should be suctioned to evacuate any obstructing blood or debris.

Labored breathing with asynchronous movement of the chest and abdomen and dull or quiet lung sounds is consistent with pleural air or fluid and warrants immediate thoracocentesis. Thoracocentesis should be performed before obtaining radiographs because animals with respiratory distress may decompensate quickly; assessment with ultrasound may be less stressful but also should not delay therapy.

When a negative pressure cannot be achieved during thoracocentesis, repeated centesis or continuous drainage of the pleural space by thoracostomy tube is required. Large quantities of whole blood removed on thoracocentesis or ongoing leakage of air after 72 hours of pleural drainage are indications for surgical exploration of the thorax. Large volumes of blood aspirated during a centesis may be collected in an aseptic fashion into an IV bag or blood transfusion bag because they may be used for autologous blood transfusion. An open chest will require placement of an occlusive bandage to limit airflow and may require intubation with positive pressure ventilation or urgent surgical correction.

The thoracic focused assessment with sonography for trauma technique can help diagnose pneumothorax, pleural effusion, or thoracic wall trauma and provides an alternative to radiographs when performed by a skilled sonographer. The thoracic cavity should be palpated for rib fractures, flail segments, avulsion of ribs, torn intercostal muscles, and herniations. When flail segments impair ventilation, the segment is stabilized by securing it to an external frame or cast, formed to the shape of the thorax. Penetrating wounds over the chest should be explored under anesthesia for debridement and repaired after the patient is stabilized; the thorax may need to be surgically entered to inspect damage to underlying tissues, repair or debride tissue as necessary, lavage the thoracic cavity, and place a thoracostomy tube. Samples for bacterial culture should be collected and antibiotics initiated.

As the animal's condition allows, thoracic radiographs (two or three views) should be obtained to assess for injury to the lungs, diaphragm, thoracic wall, and extrathoracic tissues. In many cases, a dorsoventral view will help to reduce undue stress to a patient with thoracic trauma. Many of the above-listed injuries may show up on routine radiographs; however, radiographic evidence of pulmonary contusions may not appear until 12–24 hours after the initial injury. A CT scans provide additional information and may be used as an alternative to radiographs.

The heart should be ausculted and an ECG evaluated for arrhythmias. Arrhythmias may not be present at the time of injury but develop 12–48 hours after the event as myocardial contusions and hypoxemia affect the cardiac conduction system. Common arrhythmias seen after thoracic trauma include sinus tachycardia, ventricular premature contractions, and ventricular tachycardia.

Treatment with lidocaine or other antiarrhythmic medications is warranted if:

  • arrhythmias impair perfusion

  • rate is rapid and sustained (>180 bpm in dogs)

  • ventricular contractions are multiform

  • prefibrillatory rhythms are present:

    • R on T phenomenon

    • torsades des pointes

    • ventricular flutter

Abdominal Trauma

The extent and severity of abdominal injuries may not be apparent on initial examination, unless there is visceral herniation outside the body cavity. The abdominal surface should be examined closely for evidence of bruising, abrasions, lacerations, protrusions, localized swelling, herniations, distention, and pain. Animals with evidence of abdominal pain that are in shock are considered to have intra-abdominal hemorrhage until proven otherwise. Rupture (crush) or laceration of the spleen or liver are the most common sources of intra-abdominal hemorrhage. However, all abdominal organs are susceptible to the shearing and crushing forces from blunt trauma. Other common sources of abdominal bleeding include avulsed mesenteric vessels, damaged muscle, or avulsion of the kidneys in the retroperitoneal space.

Approximately 40 mL/kg (just less than half of the circulating blood volume) is necessary before free blood in the abdominal cavity will be evident by palpation or external visual inspection; this volume is associated with signs of poor perfusion (shock). Smaller volumes of abdominal fluid may be identified with radiographs, centesis, or ultrasound of the abdomen. Abdominal distention from hemorrhage may become apparent if aggressive fluid resuscitation increases blood pressure and disrupts blood clots that provided hemostasis. Small volume fluid resuscitation to achieve a low-normal blood pressure endpoint (90 mmHg systolic, 60–80 mmHg mean) is indicated to avoid sudden increases in arterial or venous pressures. When ongoing abdominal hemorrhage is confirmed, hindlimb and abdominal binding is indicated early to reduce the amount of hemorrhage until hemostasis is accomplished.

After injury of any abdominal organ, clinical signs of organ dysfunction or hollow viscus rupture typically develop over a period of hours but may be longer or shorter depending on the nature and severity of the injury. Acute abdominal pain is a key physical finding. Survey abdominal radiographs can demonstrate organ displacement, distention, rotation, or free abdominal gas or fluid. Fluid can be recovered by four-quadrant abdominocentesis. Using the abdominal focused assessment with sonography for trauma (AFAST) technique, even small amounts of free fluid in the abdomen can be identified and aspirated using ultrasound guidance.

When free fluid is not readily identified, a diagnostic peritoneal lavage can be done. A fenestrated catheter is placed into the peritoneal space, and warm isotonic saline (20 mL/kg) is infused into the abdomen. The fluid is allowed to dwell for several minutes and distribute throughout the abdomen; it is then drained and evaluated. Clear fluid indicates that the possibility of significant abdominal hemorrhage is minimal. Fluid with a 1% PCV indicates mild abdominal hemorrhage, whereas fluid with a PCV >5% indicates significant abdominal hemorrhage that warrants careful monitoring.

Fluid obtained from the abdomen should be examined cytologically for evidence of WBCs, plant or meat fibers, and extracellular or intracellular microorganisms. Biochemical evaluation for creatinine and potassium, bilirubin, amylase, and phosphorus may help to identify urinary system rupture, gallbladder rupture, pancreatic injury, or ischemic bowel, respectively. Abdominal fluid glucose that is 20 mg/dL ( ~1.1 mmol/L) or more below peripheral blood glucose is characteristic of a septic peritonitis and warrants exploratory surgery. The abdominocentesis, peritoneal lavage, or AFAST scan can be repeated in several hours if fluid from the first assessment did not indicate a significant problem but the clinical signs continue or progress. Retroperitoneal, fascial, or intramuscular (body wall) hemorrhage or hemorrhage into the GI system can be more challenging to identify.

Criteria for emergency exploratory laparotomy include:

  • ongoing hemorrhage

  • inability to stabilize shock

  • organ rotation, entrapment or ischemia

  • diaphragmatic hernia

  • evidence of organ rupture or peritonitis

Some simple bladder ruptures may be amenable to medical management and placement of an indwelling urinary catheter connected to a closed urinary collection system. Surgery to repair a diaphragmatic hernia should not be delayed, particularly with gastric displacement into the thoracic cavity, respiratory compromise, or ongoing hemorrhage.

Retroperitoneal, severe fascial compartment hemorrhage (associated with pelvic fractures), or hemorrhage into a hollow viscus is suspected in acutely traumatized animals that have a declining PCV/total solids, nonresponsive hemorrhagic shock, and no significant findings on abdominocentesis, peritoneal lavage, or AFAST scan. Radiographs typically show expansion of soft tissue and loss of detail in the retroperitoneal space. An IV pyelogram should be done to help delineate disruption in the renal vascular supply or in the retroperitoneal portion of the ureter before proceeding with exploratory surgery in this situation; alternatively urine production can be identified intraoperatively with a cystotomy and observation of the urethral papilla.

Damage control resuscitation paired with damage control surgery may help optimize patients with severe trauma. Damage control resuscitation includes early use of blood products to hypotensive endpoints to avoid the development of a lethal triad of acidosis, coagulopathy, and hypothermia that is common in severely traumatized patients. Damage control surgery is a limited laparotomy designed to only control hemorrhage and/or minimize contamination but not perform definitive surgical repair to avoid similar clinical complications. Definitive care is delayed until the patient is able to tolerate an extended anesthesia and surgery.

Acute traumatic coagulopathy can occur in patients with severe trauma. This syndrome, which develops due to tissue injury, hypoperfusion, hypothermia, hemodilution, metabolic acidosis, and systemic inflammation, results in increased bleeding. It may be diagnosed with a thromboelastogram and is treated with a combination of a blood product to address hypocoagulation along with antifibrinolytic agents (eg, tranexamic acid, aminocaproic acid) to address hyperfibrinolysis.

Key Points

  • Analgesia is necessary and oxygen will commonly be as well.

  • Hypothermia, hypocoagulation, hypotension, and acidosis should be minimized.

  • Definitive care may need to be delayed in order to stabilize the patient through damage control resuscitation or surgery.

  • Regular patient scoring and assessment of perfusion, respiration, and neurologic status is needed.

  • Kirby's Rule of 20 is useful for any critically ill patient.

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