Video-assisted thoracoscopic-guided reduction and external stabilisation of traumatic rib fractures in a cat

Abstract

Case summary

An 11-year-old male neutered domestic longhair cat was presented to an emergency referral hospital after sustaining severe injuries isolated to the thorax after a dog attack. Initial stabilisation included oxygen supplementation, intravenous fluid therapy, point-of-care ultrasound (POCUS), serial blood gas analyses, thoracic and abdominal radiographs, opioid analgesics and broad-spectrum antibiotics. CT revealed multiple internally displaced rib fractures that punctured through the mediastinum and were in intimate proximity to the cranial vena cava and proximal aortic arch. Video-assisted thoracoscopic surgery (VATS) was performed using a 2.7 mm 0° short laparoscope to place a custom-made fibre glass splint via percutaneous suturing to accurately reduce the rib fracture fragments without further damage to the intrathoracic structures. The splint remained in place for 6 weeks. At the 8-week recheck, the cat had no evidence of cardiovascular or respiratory compromise and was able to resume normal activity. A long-term follow-up phone call was conducted at 14 months postoperatively. The owner reported that the patient has continued to do well without any complications.

Relevance and novel information

To the authors’ knowledge, this is the first report using VATS for the reduction of traumatic rib fractures in a cat. This case highlights the feasibility and success of this method and is a viable option in future clinical cases.

Introduction

Thoracic trauma resulting from penetrating injuries, blunt force trauma or attacks from other animals is common in small animals and is a major cause of morbidity and mortality.^1,2 Two studies by Kraje et al ² and Griffon et al ³ note that the risk of intrathoracic injury is high, with 38.7–87% of cats showing radiographic evidence of thoracic trauma. Notably, up to 40% of these cases may remain clinically silent for intrathoracic injury despite significant internal injury.^2,3 Cats with diaphragmatic hernias or rib fractures were more likely to exhibit clinical signs. ³ Because the cat’s thorax has greater compliance and unique anatomy compared with other small animals, it is important to thoroughly assess for concurrent intrathoracic injuries when traumatic rib fractures are identified.^2,4 Concomitant intrathoracic diseases include, but are not limited to, pulmonary contusions, pneumothorax, pneumomediastinum, pleural effusion and diaphragmatic hernia.^{2 –5} Preanaesthetic imaging, such as thoracic radiography or CT, is critical in trauma patients to identify occult injuries that may significantly influence anaesthetic risk and perioperative management.

Traumatic rib fractures in small animals are typically managed conservatively, with stabilisation focusing on pain control, maintaining cardiopulmonary perfusion and ventilation, and supporting circulating blood volume. This includes the administration of supplemental oxygen and fluid therapy (including blood products) and thoracic drainage as required. ¹ In contrast to veterinary medicine – where surgical intervention is scarcely reported – in the human literature, there is growing evidence that surgical stabilisation may reduce the length of hospital stay, time spent in intensive care and the need for extensive pain relief.^{6 –8} Given the scarcity of veterinary reports, careful patient selection is critical when considering surgical stabilisation, especially in the context of concurrent intrathoracic injury or haemodynamic instability. In addition, although video-assisted thoracoscopic surgery (VATS) offers a minimally invasive alternative to open thoracotomy, it may not be appropriate for unstable trauma patients because of the risks associated with insufflation, single-lung ventilation and limited access for vascular control.^8,9 This case report describes video-assisted thoracoscopic fracture reduction and placement of an external splint in a case of traumatic thoracic wall injury to a cat sustained by dog attack.

Case description

An 11-year-old male neutered domestic longhair cat was presented to an emergency referral hospital immediately after being attacked by two dogs. On presentation, the cat had a dull demeanour and signs consistent with haemodynamic shock. Point-of-care ultrasound (POCUS) revealed moderate B-lines bilaterally, and thoracic and abdominal radiographs were obtained revealing sternal subluxation, rib fractures, hydropneumothorax, pneumomediastinum and soft tissue injury. Pulmonary contusions were suspected in the cat, despite the lack of radiographic evidence at the time. Blood gas analysis showed hyperlactataemia (20 mmol/l), hypernatraemia (161 mmol/l), hyperglycaemia (15.3 mmol/l) and metabolic acidosis. Initial resuscitation and stabilisation efforts comprised a combination of flow-by oxygenation, an intravenous bolus of lactated Ringer’s solution (5 ml/kg IV; B Braun) and analgesia with methadone (0.2 mg/kg IV; Troy Laboratories). Electrolyte and lactate parameters subsequently normalised within 9 h. However, respiratory acidosis became evident, as indicated by hypercapnia (47.6 mmHg), a pH of 7.216 and a respiratory rate of 32 breaths/min with mild respiratory effort. One small superficial puncture wound was identified on the left ventral thorax with minimal pocketing. No other external wounds were identified. The cat was oxygen-dependent, showing an SpO₂ of 89% on room air. However, it responded well to supplemental oxygen (FiO₂ 0.35), with SpO₂ improving to 98%. The bite wounds were clipped and cleaned with a 0.05% chlorhexidine solution, to the extent tolerated by the cat without causing decompensation. The cat was treated promptly with amoxicillin-clavulanate (25 mg/kg IV q8h) as a broad-spectrum antibiotic, which was continued for the duration of hospitalisation. After 24 h of supportive care, the cat was deemed fit for anaesthesia and advanced imaging. CT imaging revealed widening of the left fourth intercostal space, dorsal and rightward displacement of the seventh sternabra, fractures of the midbodies of the right fourth and fifth ribs and the ventral aspect of the left fourth rib, along with minimal displacement and luxation of the left fourth and seventh costochondral junctions at the level of the sternabra. There was fracture and luxation of the right third and fourth ribs, causing marked displacement into the cranial mediastinum with the proximal tips adjacent to the right cranial lung lobe and ventral to the cranial vena cava and proximal aortic arch, respectively (Figure 1). There was also evidence of subcutaneous gas pockets around the thoracic wall, pulmonary contusions, atelectasis, thoracic wall swelling and scant pneumothorax. The pleural effusion identified at the time of thoracic radiography had resolved by the time the CT scan was performed.

Figure 1

CT transverse image of the preoperative scan of the proximal thorax. The fourth rib (red arrow) is seen medially displaced and in close proximity to the cranial vena cava (solid white arrow) and the proximal aortic arch (dashed white arrow)

Although early surgical intervention was recommended, the procedure was delayed pending owner consent and was performed 24 h later under a separate anaesthetic. The patient was premedicated with methadone (0.2 mg/kg IV) and induced with propofol IV to effect and maintained on isoflurane. A single dose of methadone (0.2 mg/kg) was given intraoperatively and was sufficient analgesia for the duration of the procedure. The patient’s thorax was clipped and aseptically prepared in dorsal recumbency. After clipping, paradoxical breathing was noted on the left side at the location of the previously noted rib fractures. The patient was placed into pressure control ventilation with a peak inspiratory pressure in the range of 5–10 cm H₂O. The thorax was not insufflated as there was enough exposure with the remaining intact ribs to conduct the procedure. Intraoperative fluids were administered using lactated Ringer’s solution (3 ml/kg/h; B Braun). Two thoracoscopic ports were created on the left and right sides of the ventral thorax between ribs 9 and 10, as previously described.^9,10 During the creation of the ports for cannula placement, significant soft tissue injury was discovered between the muscle layers into the thoracic cavity. Two 5 mm thoracoscopic cannulas were placed and a 2.7 mm 0° short laparoscope was used to visualise internal thoracic structures. The disruption to the normal anatomy of the thoracic cavity was much more extensive than initially expected from the preoperative CT scan. As a result, a third thorascopic port was created via a para-xyphoid approach to allow access to both hemithoraces simultaneously. ⁹ Haemostasis was achieved with a vessel sealing device (Ligasure; Medtronic). The mediastinum was disrupted from the initial trauma, allowing visualisation of the entire thoracic cavity. Extensive pulmonary contusions were observed, which were more severe in the cranial thorax, with associated adhesions between the body wall, aorta, cranial vena cava, rib fracture fragments and pulmonary viscera. Notably, there was a large haematoma on the cranial vena cava associated with one of the rib fracture fragments. The third rib was seen to be intimately associated with the cranial vena cava. Adhesions were gently broken down to release the fracture fragments, which were tractioned into reduction with Allis tissue forceps (Figure 2). The ribs were secured anatomically with circumferential sutures of 2-0 polydiaxonone (PDS; B Braun) incor-porating both rib fragments and soft tissues. Additional circumferential sutures of 0 polyamide (Dafilon; B Braun) were then used to secure the fracture fragments to a custom-made fibreglass external splint (Figure 3). Soft tissues were debrided and repaired with 3-0 polydiaxonone (PDS; B Braun) and closure of the thorascopic ports was routine. A 14 G chest drain (MILA International) was placed in the left hemithorax with thoracoscopic guidance. Radiographs confirmed appropriate drain placement and satisfactory fracture reduction.

Figure 2

(a) Intraoperative image of the fourth rib within the mediastinum in close contact with intrathoracic structures. (b) A suture is placed around the fractured rib fragment and tractioned back towards the thoracic wall. (c) The suture is secured to the external custom-made fibreglass splint and no longer within the mediastinum. (d) Note the bruising on the aorta (indicated by forceps) now visible after reduction of the fracture fragments, with the oesophagus positioned ventral to it

Figure 3

Custom-made fibreglass splint in place on the ventral thorax of the patient: (a) patient is lifted up vertically showing the external splint and (b) close-up of the external splint while the patient is lying in left lateral recumbency

Postoperatively, the cat had a delayed recovery, only regaining responsiveness 8 h after cessation of the gen-eral anaesthetic. Oxygen supplementation was necessary as SpO₂ measured 90% on room air and improved to 98% with supplemental oxygen at FiO₂ 0.35. Hypothermia (32°C) was managed by active warming using a Bair Hugger and blankets until normothermia was achieved. During the acute postoperative period, the cat showed signs consistent with shock. Two intravenous boluses of lactated Ringer’s solution (B Braun) were given at a total dose of 15 ml/kg; however, no significant haemodynamic improvement was observed. POCUS revealed poor cardiac contractility, and Doppler measurements indicated low systolic blood pressure accompanied by thready peripheral pulses. Electrocardiogram findings were within normal limits. A constant rate infusion of dopamine hydrochloride was started at 5–7 µg/kg/min, resulting in improvement in blood pressure and overall circulatory stability. Although additional testing, such as cardiac troponin testing, would have provided a more sensitive assessment for myocardial injury, the authors considered the positive response to dopamine’s ionotropic and vasoconstrictive effects sufficient to support cardiovascular function. Analgesia was provided by way of constant rate infusion of fentanyl hydrochloride (2–10 µg/kg/min) both perioperatively and postoperatively. Bupivicaine (2 mg/kg q6h) was instilled via the thoracic drain. Serosanguinous fluid was drained every 4 h via the thoracic drain, with a total output starting at 10 ml/kg/day. By 24 h postoperatively, drainage had decreased to less than 1 ml/kg/day. The drain was subsequently removed at 48 h postoperatively. Hypoalbuminaemia (19 g/l) was noted on postoperative day 2 and resolved by day 5 with nutritional support, which included a nasogastric tube during hospitalisation. The cat also began spontaneous eating approximately 30 h postoperatively.

The cat continued to respond to supportive care and was discharged 8 days postoperatively with the external splint in place. The splint was assessed weekly by a veterinarian until removal at 6 weeks postoperatively. The owner reported no complications with the splint, and the cat tolerated bandaging and splint management well. A CT scan was performed at 6 weeks postoperatively, demonstrating partial bony healing, with non-union of the third and fourth rib fractures. The ribs lost reduction and became displaced intrathoracically at some point during the postoperative period. However, fibrotic tissue developed around the area, creating sufficient separation between the rib fragments and vital structures. There was no evidence of ongoing trauma, inflammation or risk to major vessels. The splint was removed on the same day, and it was evident that some of the sutures securing the ribs to the splint had failed. Three full-thickness skin ulcers were also discovered under the splint due to rubbing; these were closed with skin staples and healed without complication. A final recheck was performed at 8 weeks postoperatively, at which time the cat had no evidence of cardiorespiratory compromise or ongoing concerns as a result of the dog attack. Long-term follow-up was conducted by tele-phone with the owners at 14 months postoperatively. The owners reported no complications and the patient had returned to normal activity.

Discussion

Traditional fixation methods for traumatic rib fractures include intramedullary pinning, interfragmentary wiring, suture approximation and placement of an external brace with percutaneous suturing performed via an open approach or a blind, percutaneous technique.^1,5 To the authors’ knowledge, this is the first report of VATS for the reduction and stabilisation of rib fractures in a cat using an external splint. The use of VATS for treating rib fractures is becoming increasingly popular in human medicine, with internal fixation specifically designed for rib fractures currently under development.^7,8,11 One study of a canine model compared exterior fixation to VATS interior fixation using custom titanium plates; it showed that although the minimally invasive approach took more time and was technically more challenging, it induced less pain and led to quicker recovery.^6,9 The minimally invasive nature of VATS not only allows magnification of the thoracic structures but also more precise and safer placement of implants. ⁹ It also allows smaller incisions to be made and avoids possible additional morbidity from rib retraction compared with an open approach. ⁹ In this case, VATS allowed for the gentle manipulation of the fracture fragments, preventing the displacement of the fragments into the cranial vena cava or proximal aorta, which could have resulted in acute death. The benefit of minimally invasive surgery was in reducing morbidity associated with large incisions, rib distraction and increased pressure on the surrounding, likely bruised, soft tissues. VATS also provided significant magnification compared with an open approach, allowing precise movements around organs and structures in view. Given the high risk of haemorrhage in this case, precision was vital to avoid lacerating major vessels during dissection and fracture reduction, all while minimising respiratory compromise. Spontaneous eating was also observed within 30 h of surgery, indicating patient comfort. Although prolonged setup time is a recognised disadvantage of thoracoscopic surgery compared with open procedures, thorough preoperative planning and efficient theatre preparation were employed to minimise this limitation.

The authors acknowledge that despite the urgency for surgical intervention due to the proximity of the rib fragments to major vessels, surgery was delayed because of obtaining owner consent. This case highlights the delicate balance between medical urgency and the logistical and ethical requirements of definitive surgical intervention in veterinary trauma cases. Although comprehensive preoperative planning was carried out to assess the location of the fracture fragments relative to the major vessels, the adhesions encountered necessitated extensive yet gentle and precise tissue handling. Haemostasis was achieved with a vessel-sealing device where possible. Although an open approach may provide broader exposure and potentially faster access, it also incurs higher morbidity and increased postoperative pain, which the authors were trying to avoid. Nonetheless, the surgical team was prepared to convert to an open approach rapidly, if required.

In this case, another challenge faced was the breakage of sutures maintaining fragment reduction, and sores from the external splint itself requiring additional intervention. As a result of the novelty of intrathoracically placed implants for rib fractures in small animals, there were none available for placement in the cat at the time of surgery. This would have provided a more stable construct and likely would have avoided the loss in reduction of the rib fragments. Despite the challenges faced in this case, it did not negatively impact on the overall outcome of the patient. A postoperative CT scan would have provided valuable confirmation of rib alignment and intrathoracic status but was not performed because of the cat’s hypothermia and postoperative clinical fragility. Intraoperative thoracoscopic visualisation and postoperative thoracic radiographs (taken during chest drain placement) indicated satisfactory fragment positioning. We acknowledge the omission of postoperative CT as a limitation and note that its inclusion would have strengthened outcome assessment.

Conclusions

This case highlights the feasibility of VATS in the surgical management of traumatic rib fractures in a cat with a percutaneously applied external splint. Further research regarding the use of VATS in cats and the development of specific custom-made splints for the reduction of rib fractures is recommended as this could potentially lead to reduced implant-related complications and recovery times for feline patients.