what's new at amvs thoracic injury following blunt

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November 2010, Issue 25

What's New at AMVS

This holiday season the

AMVS staff will be gift

giving to the animals in

need at the Longmont

Humane Society (LHS) by

hosting a food drive! We

have made a list of the

most needed items on the

LHS list and plan to collect

donations over the next

month.

We are opening this

donation drive to anyone in the community who

would like to help us reach our goal of 200 pounds of

donated goods.

For more information on how

to participate and what is

needed please contact Sarah

Benson at 303-678-8844.

'Tis the season for giving!

In This Issue

What's New at AMVS

Thoracic InjuryFollowing Blunt

Trauma

In addition to our regular ER hours,

AMVS is providing emergency and

critical care services

to your patients:

Fridays, all day

303-678-8844

AMVS is:

of 6News from Aspen Meadow Veterinary Specialists

2/15/2011https://ui.constantcontact.com/visualeditor/visual_editor_preview.jsp?agent.uid=11039574...

Thoracic Injury Following BluntTraumaBy Denise Crumbaker, Emergency Veterinarian

1. Blunt trauma is a common cause of injury in bothdogs and cats. This includes vehicular trauma, falling from height, crush/compression wounds, and human-animal interactions.

2. Major trauma to the thoracic cavity often results in injuries that can be life-threatening and must be immediately identified and addressed.

3. Pulmonary contusion is the most commonlyidentified thoracic injury after blunt trauma andtreatment is largely supportive, consisting of oxygen supplementation and judicious use of IV fluids.

4. Pneumothorax is the second most commonlyidentified thoracic injury after blunt trauma.Thoracocentesis is both diagnostic and therapeutic for pneumothorax.

5. Thoracic radiographs are an important part of thepatient's diagnostic plan, but should not be takenuntil the patient is deemed stable. This can be done after thoracocentesis. Pulmonary contusions may not initially be noted on films and may worsen over 24-48 hours.

Traumatic injury is a common presenting complaint among pets presented to veterinary hospitals. A large study performed over 30 years ago documented thatapproximately 13% of animals admitted to thehospital were for treatment of traumatic injuries.Physical trauma can be caused by either penetrating injury (i.e. projectile injury, impalement, bite wounds) or blunt trauma (i.e. vehicular trauma, falling from height, bite wounds causing crush/compression of tissues, human-animalinteractions). A study of severe blunt trauma in dogs documented that the chest was the most commonly affected individual location and that in patients with polytrauma, the chest and abdomen were the most common regions affected. In the same study, the most common thoracic injuries were pulmonary contusions and pneumothorax, with a smaller population of patients noted to have evidence of hemothorax, rib fractures, pneumomediastinum, and

PACE certified,LEED certified,

anda zero-waste

facility.



diaphragmatichernia. The purpose of this article is to discuss the most common types of thoracic injury following blunt trauma, their treatment, and overallprognosis.

Pulmonarycontusions are due to a compression-

decompression injury to the thoracic wall. This causes rapid changes in intrathoracic pressure which leads torupture of the alveoli and alveolar capillaries and subsequent filling of the alveolar air spaces with blood. The structural disruption also leads to the formation of edema within the alveoli. The presence of hemorrhage and edema within the lung leads to consolidation and hypoxemia. Multiple veterinary studies have documented pulmonary contusions to be the most frequently noted thoracic injury following blunt trauma.

Clinical signs of pulmonary contusion include bothtachypnea and dyspnea; however it is important torealize that while these signs may be present whenthe patient first presents, it is also possible that they may not develop for several hours after the trauma. Thoracic auscultation may reveal changes in lung sounds ranging from mild increases in bronchovesicular sounds to overt crackles. These changes may not be symmetrical across eachhemithorax. A study evaluating post-traumaticthoracic radiographs noted that while respiratory rate was not useful in predicting thoracic injury, abnormal chest auscultation was.



Diagnosis of pulmonary contusions is generally done through thoracic radiographs, although there is interest in using ultrasound in patients when they first present to screen for injuries or for when theymay be too unstable for radiographs. It may take up to 48 hours for contusions to become visible onradiographs. Because of this delay, it is important to still be suspicious of the presence of contusion in patients with either abnormal respiratory parameters (continued tachypnea, dyspnea, poor oxygen responsiveness despite treatment) or in patients with noted polytrauma even if initial radiographs do not indicate contusion. The presence of rib fractures should act as a red flag for underlying pulmonarycontusion. Treatment of patients with known orsuspected pulmonary contusion is largely supportive. Oxygen should be supplemented to achieve a minimal oxygen saturation of 90% measured via pulse oximetry or PaO2 of 60 mmHg as measured via arterial blood gas. Fluid support should be directed at achieving or maintaining a normal heart rate, systolic blood pressure of 100 mmHg, and adequate urine output (minimum 1 ml/kg/hr).

There have been multiple studies of fluid resuscitation in patients with pulmonary contusion, but no firm conclusions as to an ideal choice. In manypatients presenting with moderate to severe blunttrauma injuries a combination of colloids andcrystalloids can be used to achieve adequateendpoints. The goal of fluid resuscitation in patients with pulmonary contusion is to avoid excessive fluid therapy and secondary volume overload as this can worsen the formation of contusions. At this time there is no conclusive evidence to support the use of furosemide, corticosteroids, or antibiotics in the routine treatment of pulmonary contusion. For patients that cannot maintain adequate oxygenation despite oxygen supplementation, ventilatory support should be considered. Overall prognosis for dogs withpulmonary contusions is good, with one study noting an 82% survival rate. If ventilator support is required, overall survival rate drops to 30%. Specific numbers were not documented for cats.

Pneumothorax was the second most commonly documented injury in two retrospective studies of blunt trauma. It has been documented as a very common finding in cats after blunt trauma from a fall. Pneumothorax is by definition the accumulation of air within the pleural space. It can be broken down into



open pneumothorax in which air enters the pleural space via a penetrating wound and closed pneumothorax, where air enters the pleural space from pulmonary or mediastinal injury. A tension pneumothorax occurs when air can accumulate within the pleural space but cannot exit.

Diagnosis of pneumothorax can largely be made during the physical exam via observation of patientrespiration (signs of dyspnea or rapid, shallowbreathing) and thoracic auscultation. When patients are in sternal recumbency they may be noted to have decreased lung sounds dorsally or possibly diffusely with large accumulation of air. Pneumothorax can be unilateral or bilateral, so asymmetrical findings on auscultation are possible. Many patients with clinically significant pneumothorax are not stable enough for radiographs. In this case, thoracocentesis can be performed. This enables both diagnosis of thepneumothorax, but also allows for treatment to beperformed.

Equipment needed for thoracocentesis includes a 35 ml or 60 ml syringe, three way stopcock, IV fluid extension set, and needle, IV catheter, or butterflycatheter. Landmarks for thoracocentesis are the 8th

through 10th rib spaces. The needle can be slowly advanced perpendicular to the chest wall while an assistant intermittently aspirates the syringe. Once air is retrieved the chest should be completely evacuated until negative pressure is achieved. Once the patient is stabilized, or if the patient is deemed stable at the time of presentation, thoracic radiographs should be obtained to determine the degree of pneumothorax (even post-thoracocentesis) and to allow for discovery of other thoracic injuries.Further treatment of pneumothorax may includerepeated thoracocentesis, placement of thoracostomy tubes in severe cases, and exploration and repair of any open thoracic wounds. Pneumothoraces rarely require surgical intervention.

Multiple other thoracic injuries can occur with blunttrauma, including rib fractures, flail chest,hemothorax, and diaphragmatic hernias. While theseinjuries are also important to both properly diagnose and treat, the purpose of the above article was to discuss diagnosis and treatment of the two most common thoracic injuries. While radiographs are the main route of diagnosing both pulmonary contusions and pneumothorax in veterinary medicine, the astute



clinician can anticipate what injuries may be present with a combination of patient observation and physical exam findings and allow that to help guide their initial stabilization of patients presenting due to blunt trauma. Once these patients are deemedstable, radiographs can then be taken to determineoverall severity of thoracic injury and help guidefurther treatment.

Thank you for your continued support!And Happy Holidays from all of us to all of you,-Aspen Meadow Veterinary Specialists

104 S. Main StreetLongmont, CO 80501303-678-8844 (p)303-678-8855 (f)

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