Guest Blog: Pulmonary Contusions in the Small Animal Trauma Patient

Trauma in dogs and cats can cause a range of potentially serious conditions and our friends at Vet Education have developed a 4-week course addressing emergency management of trauma patients. More details about the Vet Education course are available below.

We are proud to support our friends at Vet Education and this guest blog has been kindly provided by Dr. Philip R Judge BVSc MVS PG Cert Vet Stud MACVSc (VECC; Medicine of Dogs).

 


 

 

Trauma in dogs and cats can cause a range of potentially serious conditions, from obvious injuries, such as fractures, open wounds, and external haemorrhage, to serious head trauma, internal haemorrhage, and life-threatening injuries of the chest cavity.

Despite advances in the management of trauma patients over recent decades, the morbidity and mortality that occur secondary to trauma remain remarkably high1. In fact, in a study evaluating causes of death in more than 74,000 dogs, trauma was the second-most common cause of death in juvenile and adult dogs2.

Thoracic injuries are one of the most common causes of mortality in the trauma patient3. Among thoracic injuries, pulmonary contusions remain one of the more challenging conditions to manage.

Pulmonary contusion occurs following non-penetrative, compression-decompression injury to the chest wall. The disruption of alveolar-endothelial integrity results in haemorrhage and oedema4. Interestingly, 80% of humans with pulmonary contusions also suffer non-thoracic injuries5 necessitating the clinician conduct a thorough patient evaluation and consideration of pulmonary contusions in patients presenting with injuries following trauma.

 

Lung ultrasound image showing evidence of pulmonary fluid in a patient suspected of having pulmonary contusions following chest trauma.

 

The pulmonary injury suffered in contusions, results in a secondary inflammatory reaction that leads to massive extravasation of fluid and inflammatory cells into pulmonary interstitial and alveolar spaces that results in progressive impairment in gas exchange for up to 12-18 hours following trauma. Concurrent myocardial contusion, rib fracture, or diaphragmatic hernia may also be present, further complicating patient management.

 

Radiograph of a cat that was attacked by a dog, showing a diaphragmatic hernia. Pulmonary contusions are common with this type of injury and are one of the major contributing factors to mortality.

 

Treatment of pulmonary contusions can be challenging. Oxygen therapy should be provided – ideally by intranasal cannula. Pleural space disorders, such as haemothorax or pneumothorax, should be managed to provide for maximal lung expansion during inhalation. Additionally, local anaesthesia and/or stabilisation of rib fractures, along with appropriate and timely management of diaphragmatic hernia are also indicated.

Some patients with pulmonary contusions require ventilation assistance, and careful patient monitoring is essential to identify such patients.

 

ECG tracing showing paroxysmal ventricular tachycardia, in a dog with pulmonary and myocardial contusions following trauma.

 

Administration of appropriate intravenous fluid therapy to patients with pulmonary contusions has long been an area of controversy, owing to concerns about excessive fluid administration contributing to pulmonary oedema. Scientific studies offer conflicting evidence regarding appropriate fluid administration. As a result, clinicians must therefore achieve a balance between limiting pulmonary pressures and providing adequate fluid resuscitation to avoid hypoperfusion complications of other organ systems.

Administration of large volumes of isotonic crystalloids, e.g., lactated Ringer’s solution should be avoided, as they are associated with excessive lung water accumulation and a deterioration of respiratory function and gas exchange.

A study6 in 2009 explored the concept of biphasic (early and late) fluid management of patients suffering septic shock complicated by acute lung injury – which has many facets similar to those observed in pulmonary contusions – including the presence of high pulmonary capillary permeability and inflammation. The study evaluated the relationship between adequate initial fluid resuscitation (AIFR), where patients received an initial fluid bolus corresponding to a positive fluid balance, and conservative late fluid management (CLFM), defined as an even-to-negative fluid balance measurement during the 7 days after lung injury. Mortality rates were lowest if used in combination, suggesting an additive effect of both fluid strategies (Murphy el al., 2009).

Given many patients with pulmonary contusions have traumatic injury to other organ systems (such as head trauma, fractures, open wounds, etc.) – all of which require positive initial fluid balance to ensure adequate tissue oxygen delivery, a strategy of fluid resuscitation to restore cardiac output and tissue oxygen delivery in acute resuscitation, followed by a more conservative fluid administration protocol seems appropriate for most patients with pulmonary contusions.

Frequent patient monitoring is essential and should be coupled with adequate analgesia and other supportive care in order to achieve optimal outcome.

 

Vet Education offers a comprehensive, RACE-approved 4-week online course on acute trauma management in the dog and cat, covering in detail, many aspects of the treatment of trauma, including respiratory complications. For more information, visit the Vet Education website, or email info@veteducation.com.au.

 

References:

  1. Hall, KE; Sharp, CR; Adams, CR; Beilman, G. A Novel Trauma Model: Naturally Occurring Canine Trauma. Shock 41 (1) 2014
  2. Fleming JM, Creevy KE, Promislow DE: Mortality in north American dogs from 1984 to 2004: an investigation into age-, size-, and breed-related causes of death. J Vet Intern Med 25 (2): 187–198, 2011.
  3. Simpson SA, Syring R, Otto CM: Severe blunt trauma in dogs: 235 cases (1997–2003). J Vet Emerg Crit Care 19 (6): 588–602, 2009.
  4. Roch A., Guervilly C. and Papazian L. (2011). Fluid management in acute lung injury and ARDS. Annals of intensive care, 19(16).
  5. Fulton R., Peter E. and Wilson J. (1970). The pathophysiology and treatment of pulmonary contusions. J Trauma. 10, 719-730.
  6. Murphy C., Schramm G., Doherty J., Reichley R., Gajic O., Afessa B., Micek S. and Kollef M. (2009). The importance of fluid management in acute lung injury secondary to septic shock. Chest. 136(1), 102-109.