Full thickness mesh graft in a cat with degloving wound – case presentation

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Delureanu FlorinCristian

Dr Delureanu FlorinCristian

Veterinary Center Otopeni

Bucharest, Romania

 

 

Introduction

An ample loss of skin with underlying tissue and exposure of deep components (eg. tendons, ligaments, bones) define a degloving injury. This kind of wounds are most frequent seen on the distal limbs, medial tarsus/ metatarsus. The main cause of deglowing wounds is car accident, special when the animal is dragged or pushed by a moving car. In all of the cases bacteria and debris are present in the wound.

Free grafts are described as a piece of skin detached from an area of the body and placed over the wound. There are two tipes of free grafts when we talk about graft thickness: full thickness (epidermis and entire dermis); partial/split thickness (epidermis and a variable portion of dermis). Skin grafts are using when exist a defect that cannot be closed by skin flaps or direct apposition. Two factors influence skin graft survival: revascularization and absorbtion of the tissue fluid.

Case report

A 4 years old female shorthair cat, weighting 3,25kg was presented to our clinic. Before that, the owner was at another clinic for consult and he was disappointed because they recommended euthanasia or amputation of the limb. Besides, the first vet treated the cat with Amoxi+Clavulanic Acid and Nekro Veyxym. The owner said that she went missing for about 10 days.

Clinical examination

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Picture 1. Dorsal aspect of the metatarsal wound Deep tissue is affected; low to moderate discharge is present.

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Picture 2. Ventral aspect of the wound; Note the big swelling and the holes at the base of the fingers (red arrows)

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Picture 3. Deep wound with circular aspect, approximate 1,5cm diameter located near saphenous vein

After a thorough clinical exam we found that all was normal excepting the degloving injury. The back right leg was affected. There was a massive inflammation with infection and a lot of debris on the dorsal surface of metatarsal area and ventral, above metatarsal pad. On the dorsal surface of metatarsal area (Picture 1). Besides, also in the ventral area, another wond proximal to the metatarsal pad and 3 deep holes was identified at the base of second, third and fourth finger (Picture 2). It could be distinguished the chronic aspect. A third lesion was registrated on the same leg, in the medial aspect of the thigh. This wound was deep with a circular shape (Picture 3). We estimated that the lesion occurred about two weeks ago. We register pain and high local temperature after palpation. The cat was stable, normothermic, with normal color on mucous membrane, CRT 3seconds and normal superficial lymph nodes.

 

 

 

 

 

 

 

Radiograph of the affected back limb

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Picture 4a

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Picture 4b

Two x-ray views was made to eliminate bone changes or foreign bodies (Picture 4a, Picture 4b).

Picture 4a, 4b- Specialist describe: Suspected slight thickening of phalanges cortical 1 fingers 3-4 and gently bending them. Soft tissue swelling of the tibio-tarso-metatarsian region.

 

 

 

 

 

 

 

Approach 

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Picture 5a

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Picture 5b

After evaluation, the initial recommendation include a good wound management under anesthesia. Before surgical debridment (Picture 5a, 5b), culture was done.

Picture 5a and Picture 5b – Dorsal and ventral aspect of the lesions after surgical debridment

 

Next, wound lavage was initiated with one bag of 500 ml of worm saline (the most easy way to deliver fluids on the wound is to connect the saline bag with a administration set to the syringe and needle with a 3-way stop cock a large amount of liquid is needed to be effective).

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Picture 6. Wound closure by simple interrupted suture.

Finally, this first stage ends with a wet to dry bandage. A primary wound closure was performed for the lesion placed on the medial aspect of the thigh (Picture 6), after intensive cleaning, removal of foreign bodies and dead skin .

Empirically the cat receive Cefquinome until the result arrive and for pain management we administered Tramadol 3mg/kg and Meloxicam 0,1-0,2mg/kg. The cat recover well after anesthesia.

 

 

 

Culture result

One day before performing surgery, we recived the culture result. Streptococcus canis (++++) was identified and was sensible to many antibiotics. Amoxicilin+Clavulanic Acid (Synulox) was initiate for general therapy and chloramphenicol ointment (Opticlor-Pasteur) for local therapy.

Next, a full thickness mesh graft was used on the dorsal aspect of the limb due to the length and depth of the wound and the other wound was left for healing by second intention, both being protected by bandages. In the next 10 day the limb wounds was treated in the same manner. Removal of bacteria, granulation tissue formation and the beginning of epithelization were supported by next bandages as follows: ·

Day 1 – wet-to-dry bandage was used after surgical debridment. (this kind of bandages adhere to the wound and remove the little layer of dead tissue when we take off). Soaked in warm saline 1-2 minutes before removing, they were changed after 24hours one to the other. Cotton gauze was the primary contact-layer of the bandage.

  • Day 2 and day 3
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    Picture 7a Fresh Sorbalgon is applied on both wounds. This dressing can absorb 20-30 times its weight in fluid, stimulate fibroblast and macrophage activity.

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    Picture 7b Calcium alginate dressing must be changed when the fibres transforms in gel.

– moisture retentive dressing (MDR) – calcium alginate (Sorbalgon-Hartmann) was the primary contact-layer. It is good to use when it exist high exudate like in our patient (Picture 7a, 7b).

 

 

 

  • Day 4,6 and day 9
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Picture 8. Hydrocolloid is indicated because he stimulate granulation and epitelisation and have a good autolytic debridment

– moisture retentive dressing (MDR) – hydrocolloid (Hydrocoll-Hartmann) was the primary contact-layer because the discharge decreased (Picture 8).

 

 

 

 

 

Describing surgical procedure:

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Picture 9. The wound is refreshed by removing the new epithelium formed around the whole wound

Preoperative surgical site preparation: The cat was placed in left lateral recumbency, with the wound exposed. The limb was clipped entirely and povidone iodine and alcohol was used for aseptic surgery. Sterile warm saline 0.9% was use for wound lavage. Meanwhile a colleague prepare the donor site in the same manner- lower cranio-lateral thorax (right side). Almost 1mm of epithelium that has started to grow from the wound edges over the granulation tissue was removed using a thumb forceps and a no. 10 scalpel blade (Picture 9). A perpendicular incision was made right at the edge of haired skin with epithelium. The wound was incised all around and after that the epithelium was removed by advancing the scalpel blade under the epithelium around

the wound. Then, undermining was performed around the wound edges. A fragment of sterile surgical drape was used over the wound to get the exact shape. The drape “pattern” was placed to the donor area.

 

 

To maintain the wound moist, i placed over it a cotton gauze moistened in warm sterile saline 0.9% while the graft is transferred.

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Picture 10. The donor site-removing the skin; black arrow show the direction of the hair groth.

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Picture 11a. Skin from dorsal thorax is advanced

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Picture 11b. Simple interrupted suture is used for skin closure.

The direction of hair groth was marked with a black arrow above the donor site so that the direction of the hair groth on the graft will be the same as the hair groth direction on the skin surrounding the wound. After that, the margins of the drape “pattern” was traced on the skin. The skin of the donor bed was incised with No.10 scalpel balde and removed using thumb forceps and Metzenbaum scissors (Picture 10). The defect left after removing the graft was primary closed by undermining and advancing the skin edges with walking sutures using 3-0 monofilament absorbable suture material and finally the skin was sutured in a simple interrupted suture manner using 2-0 monofilament absorbable suture (Picture 11a, 11b).

 

 

 

 

 

 

 

 

 

 

Preparing the graft

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Picture 12. Final aspect of the skin graft after removal

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Picture 13. The skin is stretched on the receiving bed so the incisions made in it expand.

The dermal side of the graft was placed on a polystyrene board with a thickness of 10cm covered with a sterile drape and after that we fixed and stretched with 21G needles. The subcutaneous tissue was removed from the graft. Next, made parallel incisions was made in the graft, 0.5-0.7cm long and apart (Picture 12). At the end, the graft was placed on the granulation bed and sutured with 4-0 monofilament nonabsorbable suture in a simple interrupted suture manner. Additional tacking suture was placed to ensure the expansion of the mesh incision and allow the fluid drainage (Picture 13).

 

 

Choosing the right bandage after grafting and aftercare

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Picture 14. Grassolind is ointment free of medication, broad mesh, air permeable and exudate; impregnated with neutral ointment. Ointment contain petroleum jelly, fatty acid esters, carbonate and bicarbonate diglycerol, synthetic wax.

It is important to use a nonadherent primary dressing. My initial choise was Grassolind (Hartmann), is sufficiently porous to allow easy passage of exudate from the wound surface, preventing maceration of surrounding tissue (Picture 14). The ventral metatarsal wound maintain hydrocolloid dressing (Hydrocoll-Hartmann) as primary layer. After that, a thin layer of chloramphenicol oinment (Opticlor-Pasteur) was used all around both wounds and over the graft.

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Picture 15. Note that the “half clamshell” is extended with approximately 1cm toward fingers (red arrow) so the leg does not touch the ground

Over the first dressings was applied 5cmx5cm compress (Medicomp-Hartmann) and a roll gauze was the second layer. After a few laps of gauze stirrups was placed to secure the bandage in place. Extemporaneous half “clamshell” splint (Picture 15) was made from plastic material wich was curved in such a way that the limb was fixed in semi flexion. The splint is a little bit longer than the extremity of the pelvic limb (“toe-dancing” position), thus provide a maximum relief pressure. In the proximal area, under the splint, I put cotton to prevent pressure injuries on the caudal aspect of the thigh. Applied from proximal to distal and with moderate tension, elastic warp was the final protective layer of the bandage and it was secured at the proximal end with tape.

 

 

 

 

Changing bandages

The bandage was changed in day 1, 3, 5, 7 and 10 post op. In day 10 the suture material was removed from the graft and from the donor site. From day 17 to day 29 hydrogel (Hydrosorb-Hartmann) was used as primary bandage layer and the bandage was changed from 4 to 4 days. In day 29 no discharge was present in the bandage; the wound was completely healed and 0,2-0,4 mm of hair was present in the center of the graft.

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Picture 16. Delayed healing on day 45 – epitelization stopped at this level.

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Picture 17b. Honey improve wound nutrition, promotes the granulation tissue and epithelization, reduce inflammation and edema. Also it has a wide antibacterial effect.

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Picture 17a. DTL laser type is alaser light emitting diode in the red field (wavelength 650 nm) and infrared (wavelength 808 nm) of the light spectrum with next clinical effect: anesthetic effect; decreases edema and inflammation; activates microcirculation; stimulates wound healing; improves tissue trophicity; reflexogenic effect.

A delayed healing occurred at the wound in the ventral region (Picture 16). From day 29 to day 59 epithelization has advanced very hard and granulation tissue has captured an appearance of ulcer (in this time the wound was asepseptic prepared and hydrocolloid and hydrogel was used as primary layer bandage and without the splint). In day 59 the wound was refreshed on the surface with a scalpel blade and laser therapy (Picture 17a) and medical Manuka honey (Picture 17b) was used daily for 14 days. After that, a complete healing was reached.

 

 

 

 

 

 

 

Illustrating wounds evolution after surgery

 

Day 1

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Day 11

 

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Day 28

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Day 35

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Day 49

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Day 11 after honey and laser therapy

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 Day 16 after honey and laser therapy

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Comparing day 1 and after 3 Months

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Resection of a chest wall mass- surgical technique and peri-operative analgesia

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Dr Vladislav Zlatinov

Corresponding authors :

Dr. Vladislav Zlatinov, Dr. Aglika Yordanova (Clinical pathologist), Dr. Nadejda Petrova (Anaesthetist)

 

Central Veterinary Clinic

Chavdar Mutafov str, 25 B, Sofia, Bulgaria

 

Introduction

 

Rib tumors are uncommon in small animals. Osteosarcoma (OSA) is the most common (73%). Other types include chondrosarcoma (CSA), fibrosarcoma (FSA), hemangiosarcoma (HSA).

Rib tumors tend to occur in large breed dogs and the usual location is in the costo-chondral junction. Radiographic changes include lysis, sclerosis, or a mixture of lytic and blastic patterns. Intra-thoracic invasion of adjacent pericardium and lung lobes is relatively common, so CT scans are recommended to determine the location and extent of the tumor, planning of the surgical resection, and clinical staging for pulmonary metastasis1.

 

Chest wall resection is recommended treatment for the rib tumors 2. The surgical approach is the identical to intercostal thoracotomy, but caudal and cranial margins include a minimum of one intercostal space and rib, while ventral and dorsal margins should be a minimum of 2 cm from the tumor.  Because of the large defect present, a need for autogenous and/or prosthetic reconstruction techniques is often necessary. Autogenous reconstruction techniques include the latissimus dorsi and external abdominal oblique muscles, and diaphragmatic advancement following resection of caudal rib tumors 3. Prosthetic reconstruction with non-absorbable polypropylene mesh, alone or in combination with autogenous techniques, is recommended for large defects. Autogenous reconstruction is preferred in humans because of a high complication rate associated with prosthetic mesh, such as infection and herniation. These complications are rarely reported in dogs following chest wall reconstruction with prosthetic mesh. Up to six ribs can be resected without affecting respiratory function in dogs 4.

Thoracic surgery in small animals is considered a painful procedure, resulting in alterations in pulmonary function and respiratory mechanics. Appropriate analgesic protocol may improve outcomes. Systemic administration of opioids and NSAIDs, intercostal and intrapleural blocks, and epidural analgesia are among the most common options for pain management after thoracic surgery in small animals 5.

 

 

Case report

 

A 10 years old male pitbull dog, weighting 24 kg was presented to us. The owners had been to three veterinary consultations before, the chief complaint being lameness at the right front limb. The cause was suggested to be a “lump” on the right thoracic wall. Based on an X- rays study and clinical examination, so far the owners were discouraged to pursue the further surgical treatment, because the procedure was supposed to be too aggressive and painful. The dog was prescribed palliative NSAIDs therapy.

 

 

Clinical examination

 

Fig1

Fig.1

We did a thorough clinical exam, revealing normal behaviour, good over-all body condition; signs of multiple joint arthritic diseases were found- elbows and stifles decreased ROM and capsules thickening. On the right cranio- ventral thoracic wall we found protruding, egg- size oval mass, widely and firmly connected to the rib cage (Fig.1).

 

 

 

Diagnostics

 

Radiograph of the right elbow revealed advanced elbow arthritic changes.

Fig 2

Fig.2

Additionally, orthogonal thoracic radiographs (+ oblique one) were done, demonstrating large infiltrating mass, with heterogenous lytic and proliferative mineralised pattern, originating at the costo-chondral junction of the 4-th rib (Fig.2).

 

 

 

 

 

unnamed

Fig.3

A fine needle aspiration was done and evaluated (Fig.3).

The pathologist remarks:

“Clusters of  fusiform mesenchymal cells, with obvious signs of malignancy- pleomorphism, increased anisokaryosis and anisocytsosis, basophilia, multinucleated cells . Occasional osteoclasts, macrophages and neutrophils were noted. No osteoid/chondroid was found in the examined material. The tumor was classified as malignant mesenchymal– fibrosarcoma, chondrosarcoma or osteosarcoma.”

 

 

Fig4

Fig.4

A computer tomographic study was accomplished and the mass’s margins investigated carefully. A mineralised tumor centre (from the distal third of the 4-th rib) was found; also soft tissue aggressive expansion in the neighbour intercostal spaces -3-th and 5-th. Typically for the chest wall masses, there was an eccentric growth- the 2/3 of the mass volume protruding into the throracic cavity, extruding the pulmonary parenchyma and contacting the heart on the right side. No lung metastases were noticed on the scans (Fig.4, video 1).

 

Complete blood work was done and found normal. Including normal Alkaline Phosphatase level, considered favorable prognostic factor.

 

After a discussion with the owner, a decision for surgical resection was made.

 

 

Anesthetic protocol

 

Premedication with Medetomidine and Butorphanol was used, followed by Propofol induction. The maintenance was sustained by Isoflurane and Ketamin drop in the fluid sack.

 

Peri-operative analgesia, Anesthetists remarks

 

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Fig.5

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Fig.6

The thoracic wall resection is considered very painful procedure, so a corresponding analgesic strategy was built and applied. A continuous post operative segmental epidural analgesia application was provided. T13—L1 epidural puncture (by Tuohy needle), was done and an epidural set catheter (B. Braun) was inserted till the 5-th thoracic vertebra(Fig.5-6). The catheter was safely attached and maintained for 48 h post op, during the patient’s stay in the clinic. The agent delivered through, was Levobupivacain (0,5 %), one 1ml every 4 hours, including pre op.

 

 

After the mass removal, a soaker catheter was sutured at the ribs resection edges; another one was applied between the skin and muscle flap, covering the defect. Both catheters were connected to an elastomeric pump (B. Braun), delivering locally 5 ml/h of 1% Lidocain for 96h (including outpatient period) post operatively.

 

The rationale behind additional soaker catheters was to suppress maximally the nociception transfer, including the sensation through the non- blocked cervical spinal nerves. Also we contemplated- removal of epidural catheter at the time of discharge, but leaving the delivery pump, providing residual local analgesia.

 

Cimicoxib (Cimalgex) was prescribed for 10 days post op. No opioids were used in the recovery period.

 

 

 

Surgical protocol (surgeon remarks)

 

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Fig.7

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Fig 9

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Fig10

After macroscopic mapping and drawing, a rectangular shaped, full thickness (skin, muscle, ribs and pleura) en bloc excision was done (Fig.7).  This included partial ostectomy of 3-th, 4-th and 5-th ribs. Caudal intercostal thoracotomy was performed first, permitting evaluation of the intrathoracic extent of the tumor. Special attention was applied at the proximal approach to ligate safely the three intercostal arteries and veins. No visceral lung pleural or pericardium adhesion were noticed. Careful electrocautery haemostasis was done at the muscles’ cut edges.  The removed mass was macroscopically evaluated for “clean” margins, and a reconstruction of the large defect was preceded (Fig.8). A double (folded) polypropylene mesh (SURGIPRO®TYCO) was sutured to the wound edges, using simple interrupted pattern (3-0 PDS material). A latissimus dorsi muscle flap was advanced to cover and “seal” the defect (Fig.9). The air content was evacuated with aspirator on the final closure; no chest drain was left in the thorax. Two soaker catheters were applied in the wound; the skin was closed by double pedicle advanced flap technique and simple interrupted pattern (Fig.10).

 

 

 

 

Post operative care and follow up

 

 

 

Fig 11

Fig. 11

The dog’s chest was loosely bandaged; the elastomeric pump and epidural catheter were securely fixed to the body(Fig.11). I.v. antibiotics and fluid support was continued for 24 hours post op.

Provided very effective local analgesia- the dog revealed excellent comfort immediately after the surgery (video 2,3,4). We paid special attention to any pain signs- excessive vocalization, hyper-excitement, panting, tachycardia, behavior abnormalities, etc. No such were present and the patient started eating the next day after surgery; it was discharged 48 after the procedure. No ambulation deficits were seen with the Levobupivacain application. The elastomeric pump was removed on the 4-th day. Mild to moderate serosanguineous discharges from the wound were present for 10 days after the surgery.

On the 14 days recheck the wound was healed and the sutures were removed; the patient showed excellent clinical recovery (Fig.12).

 

 

 

 

Discussion

 

 

The surgical excision is considered the first treatment of choice for malignant rib tumors, but a question about the long term prognosis and rationale behind an aggressive surgery could be raised. As mentioned above, the most common rib tumors are osteosarcomas (OS)  and chondrosarcomas(CS). They have quite different prognosis- OS is rarely cured, whereas CS could be cured with surgery alone. Dogs with osteosarcoma that have elevation of the Alkaline phosphatase level have a much lower median survival times 6. Chemotherapy significantly increases the survival of dogs with rib OS- from a few months to about 9.5 months. Roughly survival time is increased 4 times with chemotherapy + radical resection, compared to surgery alone. Chondrosarcomas have a very good chance to be cured with surgery alone with median survival times exceeding 3 years. The other common type -fibrosarcoma and hemangiosarcoma have intermediate metastatic potential between the other two. Survival times ranging from 120-450 days with chest wall resection alone 7.

 

Dealing with motivated owners, a patient in good general health, with normal AP, and need for moderately large rib case resection size, we found good indications for tumor removal without preliminary histological verification. We suggested acceptable life expectancy in the worst tumor type scenario (the option for chemotherapy was available). While respecting previous vets’ opinions, we took into consideration the stated in the literature fact that dogs tolerate removal of a large portion of the rib cage very well.

 

Despite all this encouraging decision making facts, we would have fought ethical issues in a scenario we weren’t able to provide sufficient peri-operative analgesia of the patient. Except the ethical side, the pain associated with thoracoectomies may have potentially lethal consequence for the patient cardiopulmonary status after surgery. A thoracoectomy requires a very painful excision, involving multiple muscle layers, rib resection, and continuous motion as the patient breathes. Sub-optimal management of pain has major respiratory consequences. Inspiration is limited by pain, which leads to reflex contraction of expiratory muscles, and consecutively to diaphragmatic dysfunction (decreased functional residual capacity and atelectasis, hypoxemia).Treatment of acute post-thoracotomy pain is particularly important not only to keep the patient comfortable but also to minimize pulmonary complications 8.

 

In the veterinary literature there are suggestion for various types of analgesia provided after thoracotomies-  intercostal blocks, intrapleural lidocaine, incisional pain soaker catheters9; systemic agents as NSAIDs, opioids, NMDA antagonists (ketamine),etc. There is plenty of space for objective evidence based studies, proving the best analgesic protocol, yet.

In the presented case we applied sophisticated but uncommon noxious stimulus blockage strategy. The thoracic epidural catheter insertion is technically demanding procedure but it is very powerful tool for both intra and post operative pain control 10. Even more, it allows even preemptive pain blockage. So-called preemptive analgesia is intended to prevent the establishment of central sensitization caused by surgery induced injuries. Evidence from basic research has indicated that analgesic drugs are more effective if administered before, rather than after, a noxious stimulus.  Human studies report that the area of post-thoracotomy pain is more discrete and largely restricted to the site of surgery. Hence, any benefit of preemptive epidural analgesia is, theoretically, more apparent in thoracic surgery than in abdominal surgery.

 

It is interesting if the present tumor or the arthritic elbow lesions caused the primary clinical sign- front right leg lameness. Lameness of the forelimb had been described with costal tumors, located within the first four ribs 11. Possible mechanism is pain translation to the nerves to the limb, mechanical interference with movement or invasion into the muscles of the forelimb. After the surgical excision the owners reported lameness disappearance, supporting the tumor as the real cause.

 

 

CONCLUSIONS

 

Excision of malignant chest wall masses could be very successful. It is feasible to achieve clean cut margins; large residual wall defects could be managed with combined reconstruction techniques. Never mind the aggressive character of the procedure, an excellent patient comfort should be achieved with a combination of thoracic epidural and local wound nerve nociception blockage, as in this case.

 

 

Comments:

 

Just before the submission of this case report the histopathology result was received. It concluded:

 

Mass, originating from spindeloid to pleomorphic cells, highly cellular. The cells were round, organized in bundles and solid formations. There was moderate to marked anisokaryosis and anisocytsosis; mitotic figures frequently present, multifocally there is osetoid production.

 

Diagnosis: Malignant pleomorphic neoplasia, suspicious for osteosarcoma.

 

Long term prognosis:

 

In the case, no local recurrence is expected because of the wide margins excision. Generally the median survival time (MST) for dogs with rib OSA is 90-120 days with surgery alone and 240-290 days with surgery and adjunctive chemotherapy, and death is caused by distant metastases.  Age, weight, sex, number of ribs resected, tumor volume, and total medication dose do not influence survival disease-free interval 12.

 

A chemotherapy protocol is already being contemplated:

Carboplatin 300mg/sq.m.; 4 treatments q 21 days (Withrow and MacEwen Small Animal Clinical Oncology,2007)

 

 

If available, the long term result and the survival time of the patient will be followed and shared through the journal.

Alveolar-pleural fistula, causing spontaneous pneumothorax in a dog- surgical management

vladi prAuthor:

Dr. Vladislav Zlatinov

Central Veterinary Clinic

Chavdar Mutafov str, 25 B, Sofia, Bulgaria

E-mail: zlatinov_vet@yahoo.com

 

Referring vet: Dr. Jordan Jordanov

Introduction

 

Most commonly the pneumothorax in small animals is caused by trauma 1. It could be open or closed; closed traumatic pneumothorax is often the result of blunt trauma (HRS, automobile accidents, etc.). The mechanism includes a chest compressed against the closed glottis, the airway or lung parenchyma can rupture with resultant air leakage.

When there is no evidence of trauma,  air leakage from the lung parenchyma is termed spontaneous pneumothorax. This is relatively rare but potentially lethal condition in small animals. The most common underlying causes are pulmonary bulla, subpleural blebs/emphysema (68% of dogs); neoplasia (11% of dogs); migrating plant seeds; pulmonary abscesses; feline chronic allergic bronchitis; chronic pneumonia; heartworm disease. Siberian Huskies and large chested breeds are overrepresented for the condition2.

In internal pneumothorax, the trachea, bronchi, alveolar ducts could be the source of leakage. The alveolar-pleural fistula (APF) is a communication between the pulmonary parenchyma distal to a segmental bronchus and the pleural space, while a broncho- pleural fistula (BPF) is a communication between a main stem, lobar, or segmental bronchus and the pleural space3.This distinction is important because the treatment for the two types could vary. Indeed in the veterinary literature there are not too many publications, regarding incidence, therapy, etc. of APF.

 

 

Case report

 

Six years old, large (40kg) mix breed dog was presented to us with clinical signs of respiratory distress. The difficult breathing had started suddenly 48 hours ago. The referring veterinarian had done primary diagnostics- chest X -rays and blood work. The radiographs had revealed bilateral pneumothorax; thoracocentesis has been accomplished several times, every time evacuating more than one liter of air. The owner didn’t report any primary trauma. The day before the onset, the dog was treated with parasite prevention drug-Ivermectin 300 ug/kg , s.c.

 

Our clinical examination revealed anxiety, tachypnea- frequent (120/min) shallow breathing, distant breath sounds bilaterally, mild fever- 39.5. The patient was over- all hemodynamically stable- normal mucous membranes, strong femoral pulse.

Emergency care

 

After sedation with Butorphanol + Midazolam (i.v.), thoracocentesis was done at the right 10-th intercostal space. Almost two liters of air were removed.

 

Diagnostics

 

Orthogonal chest radiographs (just after the centesis), revealed residual pneumothorax, left lung lobe collapse (atelectasis), right shifted cardiac silhouette (Fig.1). Pleural fissures were detectable, but no significant pleural effusion was visible; the lung pattern showed mild signs of diffuse alveolo-interstitial pattern, more pronounced in the right hilus area.unnamed

 

A serological Diroffilaria test (Anigen, Bionote, Seul, Korea), done by the referral veterinarian went out positive. Nevertheless, the disease was not confirmed by us- the SNAP 4Dx Test (Idexx comp.) and microfilaria blood smear tests came out negative. Larvo/ovoscopic test (done 6 days later) was negative.

Working algorithm

 

Working algorithm Within the next 8 hours, several thoracocentesis and air evacuations were accomplished, demonstrating the significant air leakage present. The underlying cause was not evident- a spontaneous rupture of a lung lesion (bulla) was supposed. A bronchoscopic or thoracoscopic diagnostic options were not available. A CT study could be used but needed transport to another facility, which was evaluated as too risky. Because of the lack of any signs of lung sealing within 56 hours, an open chest surgical exploration was planned and accomplished.

 

Anesthetic protocol

 

The patient was pre medicated with Acepromazine/ Butorphanol combination- i.m., low range doses. After 10 minutes of hyper oxygenation the patient was induced in anesthesia rapidly (Diazepam/ Propofol) and intubated as fast as possible. The maintenance was achieved by Isoflurane gas (2-3%) and Ketamine drop. Positive end-expiratory pressure (PEEP) of 15 cm H20 ventilation was applied to the patient, using anesthetic ventilator (Midmark Matrix). The hemodynamic parameters- saturation, pulse rate, blood pressure was closely monitored during the whole surgery; no anesthesiological incident was met. The PEEP was adjusted ( up to 25 cm H20), accordingly to the desired lung hyperinflation after chest opening.

 

Surgical protocol

 

A standard ventral median sternotomy approach was used. The sternum was osteotomised (with oscillating saw) in the mid line – from the 3-th to 7-th sternebra; later the approach was extended further caudally , leaving intact the end part of the xiphoid process. Two automatic wound retractors were placed cranially and caudally, achieving excellent approach to all chest structures.

A thorough cavity inspection was accomplished. No free fluid or obvious air leakage was found. Chest walls and heart had a normal surface and structure. The lungs had a normal surface, structure and inflation except one collapsed lobe area.  The pathology was found in the caudal part of the left cranial lung lobe-  atelectasis , with lack of parenchyma inflation. On the dorsal surface there were three small (1 mm) confined lesions areas with serosal  surface defects,filled with granulation tissue (Video 1)

 

A bubble test was accomplished- flooding the chest with warm sterile saline and searching for bubbles during positive-pressure ventilation (up to 40 cm H20). Surprisingly no source of air leakage, including the lesion area, was found.

A second careful  and thorough lung exploration was done, but did not reveal any other areas in question. Finding the visible pathology , we proceeded towards partial lobectomy of the distal collapsed caudal part of the cranial left lobe. One relatively big bronchus and blood vessel were encountered proximally and ligated individually. The resected area was first sutured with  continuous overlapping suture (3-0 PDS). The edge of the incision is over sewn in continuous pattern (4-0 PDS). The sutured sites were tested for leakage again. The lung tissue was separated for histology examination.

Single chest tube was placed before thoracic cavity closure. The thoracotomy was closed routinely, using several full cerclage wires, compressing tightly the osteotomised stenebrae

(Fig.2).vl 5

 

 

Postoperative care and follow up

 

Peri operative analgesia was provided using multimodal approach:

 

NSAID (Meloxicam s.c.) – pre and post op

Transdermal Fentanyl patch 100 μg (applied 4 h pre op),

MLK (Morphine, Lidocaine, Ketamin)  i.v. infusion for 10 hours post op

Local pleural infiltration- 20 ml Levobupivacaine (2,5 mg/ml) in the chest tube every 6 hours.

 

Continuous air suction was not applied but the chest tube was tested and air evacuated every 2 hours.

 

The patient showed fast anesthetic recovery with good pain control after the procedure (comfortable laying in sternal recumbence).

 

The air presence was monitored carefully. After 2 hours of negative finding, an abundant air accumulation started, just as the preoperative status. With the frequent air evacuation, the next 24 h the patient was respiratory stable with occasion onsets of tachypnea. The chest tube was closely examined, and found adequately airtight.

 

Additional diagnostics

 

Significant air leakage (>500 ml/h) was appreciated in the next 24h after the surgery, with no tendency of rate deceleration.  This let us look for a major broncho-pleural fistula with hidden /complex localization. We used an uncommon diagnostic technique- contrast bronchography. After induction in short light anesthesia, the dog was intubated and 3,5 ml Omnipaque (Iohexol 350 mg/ml) were injected through the endotracheal tube, with the head in elevated position. The procedure went uneventfully; the X rays, following 2 minutes of Ambu bag hyperventilation revealed normal bronchial tree, without noticeable pathology(Fig.3).vl 8

Second explorative surgery

 

Considering, that we didn’t adequately addressed the air leakage, and after a fair discussion with the owner we reluctantly decided to go for a second explorative surgery.

 

The same anesthetic protocol was used; we approached the cavity through the recent thoracotomy wound. The lobectomy site was explored, showing perfect sealing and early signs of fibrin formation on the edge. The chest tube intercostal passage looked smooth and nice without soft tissue laceration.

This time, all the lung lobes showed normal inflation and again a frustrating lack of any leakage signs. Special attention was payed on to explore the obscure hilus lung areas. Two saline/bubble test were accomplished without result. At the end (after 30 minutes exploration) an air leakage was demonstrated by an accidental left lung lobe maneuvering, while the chest still filled with saline. We found a single, small (0,5 mm) , barely visible, smooth margins (obviously epithelised) opening on the dorsal surface of the cranial left lung lobe (Fig.4 ). Based on the macroscopic findings we diagnosed alveolar-pleural fistula, having stealthy dynamic characteristics- emissive only in specific lung lobe positions, and dorsal body recumbence not facilitating it (look at the discussion section)

 

A single purse- string  suture (4-0 PDS) was laced around the fistula opening. After the sealing confirmed and final chest lavage the thoracotomy was closed routinely, leaving a chest tube (Fig.5 ).vl 4

 

Follow up and result

 

Immediate cease of the air accumulation was evident after the second surgery (Fig.6). Despite the fast recovery, the dog was closely monitored in clinic for 3 days, afterward the chest tube was removed and the dog discharged for home care.vl 6

The histological report that came later was suggesting not specific granulomatous lung parenchyma changes, with no causative agent (parasites/larva) present in the tested tissue.

 

The dog made full clinical recovery. Its condition was followed 4 years after the thoracotomy surgeries (Fig.7 ).vl 3

 

Discussion:

 

In the presented case report multiple discussions could be initiated. They may regard the possible underlying cause of the pneumothorax, the best diagnostic tools for APF, and the best treatment – conservative vs. surgical, sternal vs. intercostal approach.

In our case we were able to confirm the mechanism of air leakage but we couldn’t reveal the exact primary cause of the lesions. Considering the anamnesis (deteriorating after ivermectin treatment) and the morphology of the lesions- small localized, discreet , we supposed parasitic) migration that had caused alveolar-visceral pleural fistulation. The adult or larva forms of some nematodes may have caused this.

There are numerous evidences that  confirm that D. immitis could cause spontaneous pneumothorax (sometimes lethal) 4,5. There are case reports of a Angiostrongylus vasorum causing massive lung lesion and spontaneous pneumothorax6. Ascaris larvae invasion was reported as a cause of spontaneous pneumothorax in humans7.

Despite we suggest parasitic etiology, it is beyond our knowledge and the scope of the report  to evaluate the morbidity potential of the mentioned or other (Capillaria, Oslerus) parasites. Nevertheless the cause, our retrospective interpretation of the lesions showed these: the fistula canals in the caudal part of the cranial lobe (found at first surgery) had collapsed, causing no serious  air leakage, whereas the cranial fistula (found at the second surgery) was covered with epithelium, preventing it’s successful sealing and creating an air valve. It was interesting that despite its small size the APF was capable of causing serious leakage, with no tendency for healing. Indeed, the small size and the normal local serosal surface around made it difficult to distinguish during both surgeries. Another misleading factor was it’s dorsal localization. With the patient laying in dorsal recumbence, a leakage intermittently blocked by compression of the fistula against the thoracic wall was suggested by us (Fig.8-9 ). This could have been the reason for negative bubble tests- no air leakage, unless lobe manipulation and lifting it from the thoracic wall.Untitled-1

In the presented case, we didn’t had the chance to use advanced imaging diagnostics, so we relied on surgical exploration as diagnostic and vl 9therapeutic option, as recommended in many veterinary sources. We were able to manage the case successfully, but met some difficulties and a revision surgery was needed. It is interesting to suggest how useful could be the advanced imaging tools in the diagnose of APF. Increased accuracy (compared to chest radiography) in finding pathologic lung bullas/ blebs have been proven by studies8.9. One study comparing the accuracy of radiography and CT for bulla and bleb identification in dogs with spontaneous pneumothorax found: radiography to be accurate in 16% of cases and CT to be accurate in 80% of cases. In our case, such circumscribed , air filled structure was missing, so it is questionable if the small air leakage source (APF) could be precisely identified. Possibly, just suggestive signs of gross hypoventilation of the cranial left lung could have been found.

Our suggestion is that a bronchoscopy could also be inconclusive, dealing with a fistulation of small alveolar duct, not accessible for examination from the segmental bronchi. It is interesting if a thoracoscopy study could find such small APF. In a 2003 study,10,11 spontaneous pneumothorax, caused by bullas was successfully diagnosed and treated in three dogs using thoracoscopy,

An argument for a more consistent conservative approach- constant air evacuation system for longer period (>4 days), may be raised. Knowledge  about potential causes of spontaneous pneumotorax is important factor when considering surgical versus nonsurgical management. We based our clinical decision on several reports that show the advantages of the more aggressive surgical  management in canine patients . In one study, recurrence rates and mortality rates for dogs with spontaneous pneumothorax treated surgically (3% and 12%, respectively) were lower than for dogs treated conservatively (50% and 53%, respectively) 1,12.

The feline patients look more prone to conservative management (first choice treatment) of spontaneous pneumothorax, because of prevailing inflammatory ethnologies 13.

It is interesting to mention that in human patients there are publications14,15 for successfully treatment of APF by use of blood patch, synthetic hydrogel and valves, delivered endobronchialy. Watanabe spigots (IBV® valves -Olympus Corp., Japan) are specifically designed for reducing air leaks by means of total occlusion of the affected bronchus. For now, no such interventional option has been reported in the veterinary sources.

The surgical approach that we used -a median sternotomy, may be considered as more aggressive and painful than the alternative- intercostal thoracotomy. The median sternotomy is our preferred choice in such cases because it gives a vast access to all lung lobes and other thoracic structures. There are evidences that in dogs, pain, the degree of cardiopulmonary impairment, and complication rates with between two approaches do not differ 16,17, 18. In humans, median sternotomy causes less postoperative discomfort than intercostal thoracotomy19.

We recognize  that a good pain control is a critical factor , when dealing with thoracotomy patients. Post operatively pain may prevent full thoracic wall excursion, reducing the ventilation and causing hypoxemia20. Pain results in catecholamine release, which contributes to vasoconstriction, decreased tissue perfusion and arrhythmias. A multimodal medical approach was used in the case providing haemodynamic stability of the patient within two open chest surgeries.

Conclusion

 

We would like to stress out the importance of following the medical algorithms in managing such spontaneous pneumothorax cases. In rare cases, the “culprit” / the underlying cause, could not be easily identified even if we know it is there. Still a persistence and systematic approach could be rewarded even in perplexed, frustrating  scenarios

 

References:

 

  1. Puerto DA, Brockman DJ, Lindquist C, et al: Surgical and nonsurgical management of and selected risk factors for spontaneous pneumothorax in dogs: 64 cases (1986– 1999). J Am Vet Med Assoc 220:1670, 2002.