Use of vessel sealing system for multiple partial lung lobectomies for spontaneous pneumothorax

Abstract

A wolf hybrid dog was presented for dyspnea and tachypnea. Thoracic radiographs revealed a pneumothorax. A median sternotomy was performed, and multiple pulmonary blebs were identified on several lung lobes. Multiple partial lung lobectomies were performed using a vessel sealing system. The dog was discharged 4 days after surgery free of clinical signs related to surgery or pneumothorax. This case represents a novel utilization of a vessel sealing system to remove the apex of the lung when there are numerous pulmonary lesions present.

Key clinical message:

A vessel sealing system simplified multiple partial lung lobectomies in an open thoracotomy. The system reduced tissue trauma as well as the amount of normal pulmonary tissue removed while efficiently creating a seal.

A vessel sealing system (LigaSure vessel sealing device; Medtronic, Fridley, Minnesota, USA) was used to remove multiple pulmonary lesions. This technique provides successful novel alternatives to more invasive options including complete lung lobectomies and bullae ablation for treatment of multiple pulmonary blebs. This technique is useful in cases of numerous pulmonary lesions to reduce the amount of normal tissue removed and it may be used in minimally invasive approaches. To the authors’ knowledge, there are no previous reports of such a procedure in the veterinary literature.

Case description

A 3.6-year-old 37.9-kg, spayed female, wolf hybrid dog was presented for evaluation of dyspnea, tachypnea, and anorexia. Initial clinical signs were a decreased appetite which progressed over the next 48 h and the dog became lethargic and had increased respiratory effort. There was no history of trauma and the dog was up-to-date on vaccines and on monthly heartworm preventatives.

Due to the progression of clinical signs the dog was presented to the primary care veterinarian. Thoracic radiographs revealed a moderate to severe bilateral pneumothorax. The dog was then referred for additional diagnostic tests and treatment.

An initial physical examination revealed increased respiratory rate, increased effort, and decreased lung sounds in all lung fields. The results of the remainder of the physical examination were within normal limits. A complete blood (cell) count (CBC) revealed hemoconcentration (hematocrit 57%). Serum chemistry profile showed hyperalbuminemia [44 g/L; reference interval (RI): 25 to 40 g/L], hypernatremia (153 mmol/L, RI: 141 to 152 mmol/L). The dog was premedicated for thoracocentesis with butorphanol (Butorphanol; Zoetis, Parsippany, New Jersey, USA), 0.3 mg/kg body weight (BW), IV, and a local block (Lidocaine hydrochloride injection 2%; VetOne, Boise, Idaho, USA), 0.3 mg/kg BW was used in the area of the caudal, ventral thorax at the level of the 8th and 9th ribs. After the dog was prepared for a thoracentesis, a butterfly catheter was used to remove 2.5 L of air from the right hemithorax and 1.2 L from the left hemithorax. Thoracic radiographs taken post-thoracentesis showed a mild persistent pneumothorax that was improved compared to the previous radiographs. The dog was hospitalized overnight for observation. No additional thoracentesis was necessary and the dog was discharged 24 h after admission.

Forty-eight hours later the dog was presented to the emergency hospital because of increased respiratory rate and effort. Physical examination findings were as previously noted. Thoracic radiographs revealed a moderate to severe bilateral pneumothorax and the dog was prepared for thoracentesis. The dog was given butorphanol (Butorphanol), 0.4 mg/kg BW, IV, once and the area was locally blocked with lidocaine (Lidocaine hydrochloride injection 2%; VetOne), 0.3 mg/kg BW, once. A butterfly catheter was used to remove 1.2 L of air from the right hemithorax and 0.9 L of air from the left hemithorax. The dog was monitored over the weekend and transferred to the surgery service for definitive diagnostic tests and treatment.

Five days after the initial presentation the dog was placed under general anesthesia for chest tube placement and computed tomographic imaging. An IV catheter was placed and 1 L of Lactated Ringers Solution (LRS) (Lactated Ringers; Hospira, Lake Forest, Illinois, USA) was given as a bolus, followed by a continuous infusion of 180 mL/h. The dog was given hydromorphone (Hydromorphone; Akron, Lake Forest, Illinois, USA), 0.05 mg/kg BW, IV, dexmedetomidine hydrochloride (Dexdomitor; Zoetis), 2 μg/kg BW, IV as premedication and maropitant citrate (Cerenia, Zoetis), 1 mg/kg BW, IV. Cefazolin sodium (West-Ward, Memphis, Tennessee, USA), 22 mg/kg BW, IV was given as a prophylactic antibiotic before placement of chest tubes and every 90 min while the dog was anesthetized. Anesthesia was induced with propofol (PropoFlo; Zoetis), 3 mg/kg BW, IV, to effect and maintained with isoflurane (Isoflurane, USP; Piramal, Bethlehem, Pennsylvania, USA) in 100% oxygen. Prior to imaging, 24 French chest tubes were placed bilaterally and the pleural space was evacuated.

Thoracic computed tomography (CT) revealed a large amount of free air in the pleural space. The lung lobes were severely atelectatic and retracted into the ventral aspect of the thorax. There were regional areas of coalescing interstitial infiltrate within multiple lung lobes which were most severe in the ventral aspect. A well-defined oval-shaped mass was noted in the ventral most aspect of the right cranial lung lobe with minimally dilated bronchi and mild sternal lymphadenopathy. No abnormalities were observed in the perihilar area. Despite placement of the chest tubes and evacuation of the pleural space, a persistent pneumothorax was seen and complete expansion of the lung field was not achieved. No other abnormalities were seen. The owners were contacted after the CT and they consented to an exploratory thoracotomy.

The dog was placed in dorsal recumbency and prepared in a standard fashion. A standard ventral midline sternotomy was performed leaving the cranial 1/3 of the sternum intact. Hemostasis was achieved using cautery.

Intraoperative observations revealed multiple 1 to 1.5 cm bulla-like structures on the right cranial lung lobe, right middle lung lobe, and cranial portion of the left caudal lung lobe. No masses were seen and the oval-shaped mass seen on the CT was presumed to have been artifact due to atelectasis. The thoracic cavity was filled with warm sterile saline and the lungs were submerged while positive pressure ventilation was held at 20 cmH₂O. The lesion on the right middle lung lobe was actively leaking. The owners were contacted during surgery to discuss the findings, and they elected to proceed with multiple partial lung lobectomies. A dolphin tip vessel sealing device (LigaSure vessel sealing device; Medtronic) was used to perform multiple partial lobectomies (Figure 1). Once the lesion was removed a small defect was present at the apex of the lung lobe with gross changes typical after use of a vessel sealing device (Figure 2). The sites were then checked again for air leakage, none was observed. The sternum was apposed using 0 polydioxanone (Polydioxanone; Ethicon, Somerville. New Jersey, USA) in a cruciate pattern, the pectoral muscles were apposed using 3-0 polydioxanone (Ethicon) in a simple continuous pattern, and the skin was apposed using 3-0 poliglecaprone 25 (Poliglecaprone 25; Ethicon) in an intradermal pattern followed by skin staples.

Figure 1.

Intraoperative image showing the lesion at the apex of the right medial lung lobe. The tissue is held in place with DeBakey forceps (arrowhead) while the vessel sealing device (arrow) is used in a caudal to cranial direction.

Figure 2.

Intraoperative image showing the lung tissue following removal of a bleb using a vessel sealing device. The crushed zone (A), transition zone (B) and normal parenchyma (C) can be seen grossly at the surgery site. Despite these changes no additional leakage was noted from any partial lobectomy site.

A blood gas analysis performed after the partial lung lobectomies revealed respiratory acidosis with minimal metabolic compensation; pH 7.276 (RI: 7.350 to 7.450), PCO₂ 56.3 mmHg (RI: 35.0 to 38.0 mmHg), HCO₃ 26.2 mmol/L (RI: 15 to 23 mmol/L). The dog recovered well from surgery and anesthesia; however, a few hours after surgery the dog began to flail and was able to remove the Christmas tree device from the right chest tube. The Christmas tree device was replaced and a large volume of air (1.3 L) was removed. The dog was given intermittent boluses of dexmedetomidine hydrochloride (Dexdomitor; Zoetis), 1 μg/kg BW, IV, until the following morning when trazodone (Desyrel; Teva, North Wales), 3.9 mg/kg BW, PO, q12h was given. The dog recovered in the ICU and received LRS (Hospira), 120 mL/kg BW per day, hydromorphone (Hydromorphone; Akron), 0.1 mg/kg BW, IV, q6h, bupivacaine (Bupivacaine, Hospira), 1 mg/kg BW, q6h in each chest tube, carprofen (Rimadyl; Zoetis, Kalamazoo, Michigan, USA), 1.9 mg/kg BW, PO, q12h. Her SpO₂ was also monitored every 2 h for the first 12 h and her chest tubes were aspirated and the fluid and air were quantified every 4 to 6 h. Her SpO₂ during this time ranged from 97% to 100%.

Both chest tubes were removed 3 d after surgery when no air production had been noted for 24 h. The dog was then discharged from the hospital 24 h after removal of the chest tube. The dog was discharged with a 2-wk prescription of ampicillin/clavulanic acid (Clavamox, Zoetis, Kalamazoo), 14.8 mg/kg BW, PO, q12h, trazodone (Desyrel), 3.9 mg/kg BW, PO, q8h, carprofen (Rimadyl; Zoetis, Kalamazoo), 1.9 mg/kg BW, PO, q12h and tramadol (Tramadol; Amneal Pharmacy, Glasgow, Kentucky, USA), 3.9 mg/kg BW, PO, q8h. The owner was instructed to provide the dog with cage rest for 2 wk, with leash walks only when outside, and to monitor for signs of incision infection or respiratory distress.

Twenty-one days after surgery the dog was presented for a recheck examination. The owner stated the dog had been doing well at home without any complications. On physical examination her incision was healed, staples were removed, and the dog had normal bronchovesicular sounds in all fields. The dog was discharged with instructions for a slow return to normal activity. At last telephone follow-up, 12 wk after surgery, the dog was reported to be doing well with no evidence of recurring clinical signs.

Discussion

Bullas or blebs, the most common causes of spontaneous pneumothorax in dogs, are often peripheral and can be multifocal (1). They commonly occur at the apex of the lungs (Figure 3) and there is a better prognosis when only a single lesion is present (1,2). However, recent reports show more than one lesion present in as high as 37% of cases with bilateral lesions in 26% of cases (1). Surgical treatment options for multiple bullae and blebs are complete lung lobectomies, partial lung lobectomies, or bullae ablation. In complete lung lobectomies only 50% of lung parenchyma can be removed without compromising the dog’s respiratory function (2,3). Bullae ablation in humans has not been successful, likely due to burning the bulla wall which leads to prolonged air leaks (4,5). Therefore, partial lung lobectomies are recommended for this disease.

Figure 3.

Intraoperative image showing a typical lesion (arrow) seen in cases of spontaneous pneumothorax following a lateral thoracotomy.

There are several techniques for partial lung lobectomies. The most common technique involves stapling systems (laparoscopic stapling system or conventional open stapling system). The advantages of this system are ease of use and reduced surgery time. Potential complications of mechanical stapling systems are stapler failure resulting in life-threatening bleeding or “air leaking,” pulmonary parenchymal contusion, or staple line dehiscence leading to hematoma or bronchopleural fistula (6). Also, the mechanical stapling systems require use of multiple cartridge firings to achieve pulmonary resection thereby increasing costs of surgery (6). A more economical ligation technique uses absorbable suture. A continuous overlapping hemostatic pneumostatic suture is placed proximal to the lesion (7). The lung lobe is incised proximal to the suture, and the edge of the lung incision is oversewn with a simple continuous pattern of absorbable suture (7). If the partial lung lobectomy is performed near the proximal third of the lung lobe, the large bronchi and blood vessels require individual ligation to reduce hemorrhage or leakage of air. If they are damaged during ligation, then a complete lung lobectomy is recommended. Possible complications with the suture technique are small air leaks where the needle punctured the lung, a complication which may require conversion to complete lung lobectomy and use of a larger amount of foreign material (suture).

In the present case we have shown that a vessel sealing device can be used to perform partial lung lobectomies in diseased pulmonary tissue, which has not been previously reported. One study in humans used a vessel sealing system in video-assisted thoracoscopic surgery to address smaller lesions (< 2 cm); larger lesions were resected using staplers. The results from this study showed that operation time, duration of drainage, postoperative hospital stay, and postoperative complications were comparable to those using stapler systems alone (5). The advantages of using the vessel sealing system in these procedures included use of fewer staplers or suture, less foreign material, reduced trauma by not having to repeatedly insert the stapling system, and therefore less chest pain. Lastly, using the vessel sealing system allowed increased amount of normal lung tissue to be left behind after removal of the bulla or bleb (4).

Previously, the same dolphin tip vessel sealing device had been used to seal vessels including pulmonary vasculature, lymphatics, and tissue bundles up to 7 mm in diameter. Activation of the vessel sealing system uses electrosurgical radiofreqency energy that causes the collagen and elastin in the blood vessel walls to reorganize within the tissue thereby forming a permanent seal (5). Often the system is equipped with a blade activated by an operator controlled trigger. This vessel sealing system (LigaSure vessel sealing device, Medtronic) has also been studied for use in pulmonary biopsy sampling with minimal postoperative complications. In a study using 4 healthy dogs, the vessel sealing system was used to perform pulmonary biospies and there was no evidence of acute air leak (8). One dog had a small volume pneumothorax 24 h after the procedure which resolved without intervention. The study also evaluated the damage to the tissue based on histopathology. Vessel sealing systems sense the impedance of the tissue. When impedance is high enough and protein coagulation is complete, the seal terminates, thereby limiting tissue damage (Figure 2) (9). Morphologic examination of the lungs showed similar changes to those reported for peripheral lung specimens collected using sealing devices in dogs (9). There were 3 obvious zones, 1 of crushed tissue which was exposed to the bipolar plate of the vessel sealer, a transition zone of damaged parenchyma between the crush zone, and a zone of normal pulmonary parenchyma (9). The transition zone represents the region of lateral thermal injury that extends beyond the directly crushed tissue.

In conclusion, a vessel sealing system may allow multiple partial lung lobectomies without having to remove a significant amount of normal tissue for treatment of pneumothorax caused by bullae and blebs. The outcome for the dog in this case report suggests the use of a vessel sealing system for partial lung lobectomies is an effective treatment for spontaneous pneumothorax when multiple lesions are present. To our knowledge this is the first report of the use of a vessel sealing system in diseased lung tissue, as previous studies in dogs involved taking biopsy samples of healthy lung tissue. Further studies are warranted to evaluate the efficacy of vessel sealing systems for large airway or other pathologic lesions in the lungs. CVJ