By: Melissa Java, VMD, DACVECC
Board-Certified Critical Care Specialist
Veterinary Specialty & Emergency Center
Thoracic trauma can occur secondary to vehicular accidents, high rise falls, bite wounds, and human trauma (stepped on, etc.). Thoracic trauma can vary from mild to life threatening and may affect only a single organ or multiple organs. Therefore, it is important to evaluate the patient carefully for multiple systemic involvement first, including other potentially life threatening systems including brain injury and abdominal trauma. Thus, the initial exam performed by the clinician often makes a difference in outcome.
When first evaluating a trauma patient it is important to first assess the ABCs, (airway, breathing and circulation) paying close attention to the respiratory system. It is important to recognize that these patients are very dynamic and can decline rapidly over time. Multiple mechanisms are involved in causing poor oxygen delivery including hypovolemia from blood loss, pulmonary contusions, and increased vasoactive hormones and circulating catecholamines causing maldistributive blood flow.
Therefore, the initial goal of treatment is to optimize tissue perfusion and oxygen delivery.
Measuring the patient’s oxygen saturation of hemoglobin via pulse oximetry (or the patient’s PaO2 via arterial blood gas if stable) should be performed, if possible. If the patient’s oxygenation status is inadequate supplemental oxygen should be provided. With thoracic trauma, myocardial injury is always a risk; therefore, an ECG should be evaluated for arrhythmias (remembering that these can develop over time).
INITIAL DIAGNOSTICS AND TREATMENT:
If the trauma patient is unstable at presentation, the largest bore IV catheter should be placed. If possible, blood should be drawn to evaluate minimally the packed cell volume (PCV), total solids (TS), and blood glucose. Full blood work including a venous blood gas, electrolytes, lactate, CBC and chemistry panel should also be performed. If the patient presents with signs of poor cardiac output/tissue perfusion (pale or muddy mucous membranes, prolonged capillary refill time, tachycardia, poor peripheral pulses) then the patient should be adequately fluid resuscitated.
The most common cause of poor perfusion is active hemorrhage. A low TS may be indicative of blood loss. Often, the PCV may be normal or even high at presentation with acute blood loss due to splenic contraction; however, the TS may be low. After fluid resuscitation, the PCV and TS may even be lower if there is substantial blood loss. There is no specific PCV that dictates whether a packed red blood cell transfusion should be given. Instead, it depends on the clinical status of the patient. Signs indicative of the need for a blood transfusion include ongoing tachycardia, tachypnea, poor peripheral pulses (bounding or snappy), pale mucous membranes, prolonged CRT and dull mentation. In patients where there is substantial blood loss or the PCV is rapidly dropping, it is recommended to give a blood transfusion early on prior to the PCV dropping to a life-threatening level. It is important to provide adequate analgesia to trauma patients, keeping in mind that it may be challenging to determine the level of pain (if the patient is neurologically impaired).
If pleural space disease is suspected in an unstable patient, a thoracocentesis should be performed prior to taking thoracic radiographs. If a tension pneumothorax is suspected, a small incision in the intercostal space should immediately be performed to rapidly release air. Typically, these patients present in severe respiratory distress and may have a “barrel chest” appearance. If there are open chest wounds these should be covered and sealed as soon as possible and the pneumothorax should be relieved via thoracocentesis.
Thoracic trauma occurs as a result of both blunt and penetrating thoracic injury. Penetrating chest wounds can result in severe respiratory distress depending on the location. Injury to large vessels can result in a hemothorax while injury to the lungs can result in a pneumothorax. Penetrating thoracic foreign bodies should not be removed until the patient is prepped and ready for surgery. Premature removal of the foreign body can result in a pneumothorax, hemothorax and rapid cardiovascular decline. Treatment includes oxygen therapy, adequate fluid therapy, analgesia, early broad spectrum antibiotics, and surgical exploration and repair.
Blunt trauma is relatively common in patients who have been hit by cars. Blunt thoracic trauma includes pulmonary contusions, pneumothorax, hemothorax, diaphragmatic hernia, rib fracture and tracheal trauma.
Cervical wounds to the neck can result in laceration or crushing injury of the trachea. These patients will present with loud upper airway sounds to no upper airway sounds if complete airway obstruction is present.
Sometimes the sounds will vary depending on the position of the neck.
The upper airway sounds may develop secondary to edema, bleeding/blood clot formation or rarely tracheal rupture or avulsion. Some animals may not show any upper airway signs initially but may develop signs days later when airway stenosis occurs. Tracheal laceration can result in subcutaneous emphysema, pneumomediastinum and pneumothorax. A pneumomediastinum is diagnosed radiographically. A pneumomediastinum is generally a benign condition unless a tension pneumomediastinum occurs resulting in severe cardiovascular and respiratory compromise. A pneumomediastinum can lead to a pneumothorax which may require treatment. A thoracocentesis should be performed in patients who are clinically compromised from a pneumothorax. Some patients with a pneumothorax may require multiple taps, and if so, a chest tube should be placed followed by surgery if air leakage does not stop.
Pulmonary contusions are the most common injury that develops following blunt trauma. They can range from mild to severe and life-threatening. Contusions can occur immediately and worsen over the first 24-48 hrs. Contusions are diagnosed radiographically as diffuse or patchy interstitial to alveolar areas of the lungs. The contusions may not be evident initially as they can radiographically lag behind. Treatment of contusions is generally supportive including oxygen therapy, mechanical ventilation if needed, analgesia, and adequate fluid therapy.
Rib fractures rarely occur by themselves; therefore, they should prompt the clinician to evaluate for other injuries. Rib fractures may cause hypoxemia due to pulmonary trauma and/or hypoventilation from pain. Flail chest is relatively uncommon. Treatment for rib fractures/flail chest is supportive including oxygen therapy and adequate analgesia and fluid therapy. Surgery is not indicated unless there are penetrating wounds.
Diaphragmatic hernia occurs when the intra-abdominal pressure acutely increases leading to rupture of the diaphragm. The diagnosis is frequently obtained via radiographs, ultrasound, and positive contrast peritoneogram. Surgical repair of the diaphragmatic hernia is warranted. There is debate over the timing of surgery whether it should be immediate or delayed. Surgery is commonly recommended immediately if the stomach is present within the thorax or if the patients respiratory status cannot be stabilized.
Hemothorax can sometimes occur but rarely causes significant respiratory distress. However, with any significant blood loss signs of hypovolemia can occur. Treatment is supportive in nature with oxygen therapy, adequate fluid resuscitation and blood transfusions as needed.
High rise syndrome is the term given to patients who sustain injuries from a fall or jump usually from at least 2 stories or more. High rise syndrome often results in thoracic trauma including pneumothorax and pulmonary contusions as well as head, abdominal, musculoskeletal and spinal injury. Pancreatic rupture and pancreatitis have also been reported in cats.
Thoracic trauma is common in the emergency setting. Early recognition of life-threatening thoracic injuries is crucial for survival of the patient. A global approach to look for other co-morbidities is key to successful management.
Dr. Melissa Java is a board-certified critical care specialist at the Veterinary Specialty & Emergency Center. The Veterinary Specialty & Emergency Center operates state-of the-art emergency and specialty veterinary hospitals that are open 24/7/365 in both Levittown PA and Philadelphia PA. For more information about our world-class emergency and specialty care, please visit VSEC on the web at www.VSECVET.com.