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Outcome of surgical management of thoracic trauma in cats | VETgirl Veterinary Continuing Education Podcasts

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In today’s VETgirl online veterinary CE podcast, we review cats undergoing thoracic trauma. We know that cats truly have 9 lives, but is there evidence to prove this? What’s the prognosis for cats that undergo surgical management of their thoracic trauma? Lux et al wanted to evaluate this in a multi-institutional, retrospective study entitled “Factors associated with survival to hospital discharge for cats treated surgically for thoracic trauma.”

First of all, kudos to the authors, as many of our veterinary studies focus specifically on dogs or on a combination of dogs and cats, but fewer focus solely on the cat. It’s nice to see an all cat study!

This multi-institutional study involved 7 veterinary teaching hospitals. Only cats that presented with thoracic trauma and later underwent surgical intervention for their sustained thoracic trauma were included in this study. Data reviewed included signalment, any pertinent medical history, physical examination findings on admission, bloodwork results, imaging results, details of the surgical procedure, post-operative complications and causes of death or survival to discharge. Twenty-three cats met the inclusion criteria. Most recorded causes of trauma were dog attacks (35%), followed by motor vehicle accidents (26%), and unknown causes (17%). Other known causes included animal attacks (excluding dogs), impalement, projectile penetrating trauma, and trauma of unknown origin. 65% of cats had external signs of open wounds, 39% had SQ emphysema, 17% had flail chest and 9% had pseudoflail chest. (A pseudoflail chest, btw, was described as the typical paradoxical movement of the thoracic wall, but with only 1 rib fracture or no rib fractures present). Rib lesions were grouped into two categories: <3 rib fractures or greater than or equal to 3 rib fractures. The authors further categorized whether surgical intervention was required for the sustained rib fractures. Some cats presented with respiratory distress (57%). Thoracic radiographs were performed in most cats and found pulmonary contusions (37%), pneumothorax (37%), pleural effusion (26%), diaphragmatic hernia (26%), sternal fractures (26%), rib fractures (21%), atelectasis (21%), and pneumomediastinum (11%). Thirty-nine percent of cats had concurrent abdominal abnormalities including diaphragmatic hernia, abdominal body wall hernia, subcutaneous emphysema, or pneumoperitoneum. Concurrent fractures of the long bones were infrequently seen (long bones = 2), manus or pes (1), pelvis (1), and scapula (1).

Medical records were also reviewed for evidence of SIRS before or after surgery. SIRS is described in this article as greater than or equal to 3 of the following criteria identified within the same day: rectal temperature of <100℉ or >103.5℉, heart rate <140 beats/min or >225 beats/min, respiratory rate > 40 breaths/min, WBC count < 5 x 103/µL or > 19.5 x 103/µL, and band neutrophils > 5%. The article defines hypertension as SAP > 150 mmHg and hypotension as < 90 mmHg. Over half of the cats met the SIRS criteria prior to surgery with only 5 cats meeting the SIRS criteria following surgery. No association was found between cats meeting the criteria for SIRS and survival to discharge.

In this study, the cats were assigned an Animal Trauma Triage (ATT) score (from 0 to 18) on admission. The mean ATT score was 6.8. The ATT scoring system is designed to help us assess the severity of illness in animals based on easily obtainable data at the time of triage, in hopes that we can use this information for prognostic purposes and to help identify those animals in need of immediate medical intervention. The information needed for the ATT score includes things taken from our physical examinations such as indicators of perfusion (MM color, CRT, rectal temperatures, pulse quality), indicators of cardiac function (HR, rhythm, but not murmurs), indicators of respiratory function (respiratory rate and effort), visible damage to the musculature, skin, and/or eyes (lacerations, abrasion, corneal stain uptake), skeletal system assessment (mobility, weight-bearing ability, fractures), and indicators of neurologic dysfunction (central and peripheral signs). The score ranges from 0-18 with 0 being healthy and 18 being the most severe. Larger veterinary studies found that each point increase in the ATT score did result in a statistically significant decreased likelihood of survival.1 Be careful interpreting the information out there on feline ATT scores; presently there is no number cut off at which we can say that a cat is likely to die from the presenting condition. However, we can use the ATT score to say that a higher score is bad for the cat’s projected outcome. In this study (with a very limited number of cats), the mean ATT score for survival was 6.4 and the mean ATT score for non survival was 10. This did correlated with survival – in other words, cats with higher ATT scores were statistically less likely to survive.

65% of cats received thoracic surgery and 48% received abdominal surgery. Repair of diaphragmatic hernia was the most common reason for abdominal cavity surgery. Other abdominal surgeries included abdominal body wall hernia repair and exploratory surgery with resection of damaged tissues. The most common findings during thoracic surgery included skin wounds, muscular defects in the thoracic and abdominal walls, diaphragmatic tears, rib fractures, lung lobe pathology, and sternal fractures or sternal avulsions.

Just under half of the cats had recorded intra- or post-operative complications. Four cats had incisional complications, 3 suffered cardiopulmonary arrest, 2 cats experienced gastrointestinal disturbances, 2 experienced cardiac arrhythmias, and one experienced aspiration pneumonia. Other conditions that arose postoperatively included anemia, hepatopathy, coagulopathy and acute kidney injury. This article did not specify whether the cats that suffered cardiopulmonary arrest were anesthetic-related arrests or whether they were attributable to the patient’s morbidities.

All cats survived their surgical procedures, but 2 cats suffered cardiopulmonary arrest and one cat was euthanized due to failure to oxygenate unassisted in the post-operative period. As for non-survivors, this article didn’t divulge what morbidities these non-surviving cats had, but we can conclude that one of them suffered some type of coagulopathy, one suffered from aspiration pneumonia, one of them had a lung lobectomy, 2 of them had body wall injuries, and all three of them met the pre-operative SIRS criteria, but not the post-operative SIRS criteria.

This study is the first look into prognostic indicators for cats that suffer trauma warranting thoracic surgery. Other studies exist for cats requiring thoracic surgery for chronic diseases, but not for acute traumatic causes. The biggest limitation of this study is the small sample size, which makes it difficult to make conclusions regarding prognostics information; larger clinical studies would give more robust data. Another limitation to this study is that underreporting may have occurred owing to cats’ ability to mask their disease. The authors suggest that since cats have a large pulmonary reserve, many cats suffering from thoracic trauma may have gone unnoticed because they are experts at masking clinical signs and may not present to owners or to clinicians with telltale respiratory distress to trigger a thoracic workup. In this study alone, respiratory diseases produced no obvious signs of respiratory distress in over half of these cats! We should all bank this information in our clinician knowledge database and use this information when presenting to pet owners the urgency and importance of taking radiographs on the basis of known trauma rather than only on the basis of seeing respiratory distress. In other words, ideally, any trauma patient should have chest radiographs taken even if they are eupneic.

Due to the retrospective nature of this study, the authors were unable to evaluate another factor in feline trauma that may be of clinical use to us: time from sustaining injury to receiving definitive treatment (surgical intervention in this case). We still do not yet have a clinical guideline for how soon to take animals to surgery for treatment of their trauma; some suggest the sooner the better, others suggest waiting for the body to have more time to stabilize. If we can gather data regarding the time it takes from initial injury to surgical treatment and evaluate the outcomes in those animals, we may be able to finally create a veterinary guideline regarding surgical intervention time in trauma. That said, this was an important study as it allowed us to see what prognostic factors affected survival in this population of cats with trauma.

So what can we take from this VETgirl podcast? Like with most trauma cases, the prognosis is fair to good for surgical management of thoracic trauma in cats with rapid recognition, identification, diagnostic workup and treatment. Unfortunately, the worse the trauma, the higher the initial ATT score, and the worse the prognosis. Also, if your patient undergoes cardiopulmonary arrest, your patient is less likely to survive to hospital discharge (A well known fact in the ECC world).  Again, the only variable this study found to be associated with survival to hospital discharge in cats requiring thoracic surgery to treat their thoracic trauma was their initial ATT score on presentation, but no cut off score for survivors vs. non survivors can be taken from a study with such a small number of subjects. Remember, cats do have nine lives (most of the time), but they are sneaky with their clinical presentations. We shouldn’t be waiting to see overt respiratory distress before making the recommendation for thoracic radiographs to identify underlying thoracic injury. We also want to make sure that we are recognizing the criteria for SIRS and treating it appropriately and immediately. When in doubt, don’t give up on trauma cases!

Abbreviations:
ATT: Animal Trauma Triage

Reference:
Rockar RA, Drobatz KS, Shofer FS. Development of a scoring system for the veterinary trauma patient. J Vet Emerg Crit Care 1994.4(2):77-83.

Lux CN, Culp WTN, Mellema MS, et al. Factors associated with survival to hospital discharge for cats treated surgically for thoracic trauma. J Am Vet Med Assoc 2018;253(5):598-605.

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