• View in gallery

    Photograph of a cat cadaver positioned in right lateral recumbency with a minithoracotomy incision at ICS 4 on the left side. A wound retractor device is placed in the minithoracotomy incision, and a thoracoscopic port is placed at ICS 9. The left cranial lung lobe is exteriorized through the wound retractor device, and a thoracoabdominal stapling device is placed extracorporeally.

  • View in gallery

    Median (interquartile [25th to 75th percentile] range) distance from the stapler anvil to the hilus of a lung lobe of 8 cat cadavers during simulated lobectomy of the left cranial and left caudal lung lobes performed at ICS 4 (gray bars), 5 (black bars), 6 (horizontal-striped bars), and 7 (diagonal-striped bars) on the left side and of the right cranial, right middle, right caudal, and accessory lung lobes performed at ICS 4, 5, 6, 7, and 8 (vertical-striped bars) on the right side. *Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 4 on the same side. †Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 7 on the same side. ‡Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 6 on the same side. §Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 8 on the same side.

  • 1. Wormser C, Singhal S, Holt DE, et al. Thoracoscopic-assisted pulmonary surgery for partial and complete lung lobectomy. J Am Vet Med Assoc 2014;245:10361041.

    • Search Google Scholar
    • Export Citation
  • 2. Haimel G, Liehmann L, Dupré G. Thoracoscopic en bloc thoracic duct sealing and partial pericardectomy for the treatment of chylothorax in two cats. J Feline Med Surg 2012;14:928931.

    • Search Google Scholar
    • Export Citation
  • 3. Plesman R, Johnson M, Rurak S, et al. Thoracoscopic correction of a congenital persistent right aortic arch in a young cat. Can Vet J 2011;52:11231128.

    • Search Google Scholar
    • Export Citation
  • 4. Kovak JR, Ludwig LL, Bergman PJ, et al. Use of thoracoscopy to determine the etiology of pleural effusion in dogs and cats: 18 cases (1998–2001). J Am Vet Med Assoc 2002;221:990994.

    • Search Google Scholar
    • Export Citation
  • 5. Walsh PJ, Remedios AM, Ferguson JF, et al. Thoracoscopic versus open partial pericardectomy in dogs: comparison of postoperative pain and morbidity. Vet Surg 1999;28:472479.

    • Search Google Scholar
    • Export Citation
  • 6. Bleakley S, Duncan C, Monnet E. Thoracoscopic lung lobectomy for primary lung tumors in 13 dogs. Vet Surg 2015;44:10291035.

  • 7. Peláez MJ, Jolliffe C. Thoracoscopic foreign body removal and right middle lung lobectomy to treat pyothorax in a dog. J Small Anim Pract 2012;53:240244.

    • Search Google Scholar
    • Export Citation
  • 8. Dupre G. Thoracoscopic pericardial window and subtotal pericardectomy in dogs and cats. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;294301.

    • Search Google Scholar
    • Export Citation
  • 9. Monnet E. Thoracoscopic lung biopsy and lung lobectomy. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;287293.

    • Search Google Scholar
    • Export Citation
  • 10. Pascoe PJ, Mayhew PD. Anesthesia for thoracoscopy. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;255270.

    • Search Google Scholar
    • Export Citation
  • 11. Radlinsky M. Thoracoscopy in the cat: an up-and-coming diagnostic and therapeutic procedure. J Feline Med Surg 2014;16:2733.

  • 12. Nylund AM, Höglund OV, Fransson BA. Thoracoscopic-assisted lung lobectomy in cat cadavers using a resorbable self-locking ligation device. Vet Surg 2019;48:563569.

    • Search Google Scholar
    • Export Citation
  • 13. Monnet E. Lungs. In: Johnston SA, Tobias KM, eds. Veterinary surgery: small animal. 2nd ed. St Louis: Elsevier Inc, 2018:19832002.

  • 14. Singh A, Scott J, Case JB, et al. Optimization of surgical approach for thoracoscopic-assisted pulmonary surgery in dogs. Vet Surg 2019;48:O99O104.

    • Search Google Scholar
    • Export Citation
  • 15. Shamir S, Mayhew PD, Zwingenberger A, et al. Treatment of intrathoracic grass awn migration with video-assisted thoracic surgery in two dogs. J Am Vet Med Assoc 2016;249:214220.

    • Search Google Scholar
    • Export Citation
  • 16. Raveglia F, Cioffi U, De Simone M, et al. Advantages of wound retractor device versus rigid trocar at camera port in video-assisted thoracic surgery—a single institution experience. J Vis Surg 2018;4:66.

    • Search Google Scholar
    • Export Citation
  • 17. Hoddinott K, Singh A, Crawford EC, et al. Laparoscopic-assisted extirpation of falciform ligament hemangiosarcoma in a dog. Can Vet J 2015;56:355358.

    • Search Google Scholar
    • Export Citation
  • 18. Ogilvie GK, Weigel RM, Haschek WM. Prognostic factors for tumor remission and survival in dogs after surgery for primary lung tumor: 76 cases (1975–1985). J Am Vet Med Assoc 1989;195:109112.

    • Search Google Scholar
    • Export Citation

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Determination of optimal location for thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats

Jacqueline E. Scott DVM, DVSc1, Ameet Singh DVM, DVSc1, J. Brad Case DVM, MS2, Philipp D. Mayhew BVM&S3, and Jeffrey J. Runge DVM4
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  • 1 1Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
  • | 2 2Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610
  • | 3 3Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616
  • | 4 4Department of Surgery, Guardian Veterinary Specialists, 4 Hardscrabble Hts, Brewster, NY 10509

Abstract

OBJECTIVE

To determine the optimal intercostal space (ICS) for thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats.

SAMPLE

8 cat cadavers.

PROCEDURES

Cadavers were placed in lateral recumbency. A 5-cm minithoracotomy incision was made in the middle third of ICS 4 through 7 on the left side and 4 through 8 on the right side, and a wound retractor device was placed. A camera port was made in the middle third of ICS 9. Each lung lobe was sequentially exteriorized at each respective ICS. A thoracoabdominal stapler was placed to simulate a lung lobectomy, and distance from the stapler anvil to the hilus was measured.

RESULTS

For the left cranial lung lobe, there was no significant difference in median distance from the stapler anvil to the pulmonary hilus for ICS 4 through 6. Simulated lobectomy of the left caudal lung lobe performed at ICS 5 and 6 resulted in a significantly shorter distance, compared with lobectomy performed at ICS 4 and 7. Simulated lobectomy of the right cranial and right middle lung lobes performed at ICS 4 and 5 resulted in a significantly shorter distance, compared with lobectomy performed at ICS 7. Simulated lobectomy of the accessory and right caudal lung lobes at ICS 5 and 6 resulted in a significantly shorter distance than for lobectomy performed at ICS 8.

CONCLUSIONS AND CLINICAL RELEVANCE

An optimal ICS for a minithoracotomy incision was determined for thoracoscopic-assisted lung lobectomy in cats.

Abstract

OBJECTIVE

To determine the optimal intercostal space (ICS) for thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats.

SAMPLE

8 cat cadavers.

PROCEDURES

Cadavers were placed in lateral recumbency. A 5-cm minithoracotomy incision was made in the middle third of ICS 4 through 7 on the left side and 4 through 8 on the right side, and a wound retractor device was placed. A camera port was made in the middle third of ICS 9. Each lung lobe was sequentially exteriorized at each respective ICS. A thoracoabdominal stapler was placed to simulate a lung lobectomy, and distance from the stapler anvil to the hilus was measured.

RESULTS

For the left cranial lung lobe, there was no significant difference in median distance from the stapler anvil to the pulmonary hilus for ICS 4 through 6. Simulated lobectomy of the left caudal lung lobe performed at ICS 5 and 6 resulted in a significantly shorter distance, compared with lobectomy performed at ICS 4 and 7. Simulated lobectomy of the right cranial and right middle lung lobes performed at ICS 4 and 5 resulted in a significantly shorter distance, compared with lobectomy performed at ICS 7. Simulated lobectomy of the accessory and right caudal lung lobes at ICS 5 and 6 resulted in a significantly shorter distance than for lobectomy performed at ICS 8.

CONCLUSIONS AND CLINICAL RELEVANCE

An optimal ICS for a minithoracotomy incision was determined for thoracoscopic-assisted lung lobectomy in cats.

Thoracoscopy is a therapeutic and diagnostic tool used in cats1–4 that offers several advantages over open thoracotomy, including a reduction in signs of postoperative pain, more rapid return to function, and fewer wound complications.5–8 Thoracoscopy has been used for pulmonary biopsy, transection of the ligamentum arteriosum with a persistent right aortic arch, thoracic duct ligation, and pericardiectomy in cats.2–4,8 The minimally invasive nature of thoracoscopy makes it particularly appealing for use in lung lobectomy in cats.9 However, thoracoscopy in cats has some limitations, including the need for specialized anesthetic procedures (one lung ventilation [OLV]) and equipment.10,11 Furthermore, endoscopic stapling devices commonly used for total thoracoscopic lung lobectomy in dogs are too large to be safely placed into the thoracic cavity of cats without risk of iatrogenic damage to the surrounding anatomic structures.12

A technique for thoracoscopic-assisted pulmonary surgery for lung lobectomy in dogs and cats has been described.1 In that report,1 thoracoscopic-assisted pulmonary surgery was performed by creating an intercostal minithoracotomy followed by insertion of a wound retractor device, which allowed for exteriorization of the lung lobe of interest. After the lung lobe was exteriorized through the wound retractor device, a stapling device was applied to the exteriorized portion of the lung to perform the lobectomy. The technique for thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats may provide many benefits of a total thoracoscopic procedure while eliminating the need for 1 lung ventilation and a specialized endoscopic stapling device. The importance of identifying the optimal ICS and of achieving hilar resections when performing thoracoscopic-assisted lung lobectomy is emphasized because of the need to maintain oncological principles when removing pulmonary neoplasms and reduce the risk of air leaks. Investigators of a recent cadaveric study12 in which thoracoscopic-assisted pulmonary surgery was used for feline lung lobectomies reported that cadavers with a hilar cuff of pulmonary tissue > 5 mm were more likely to leak air from the cut surface.

The purpose of the cadaveric study reported here was to determine the optimal ICS for thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats. We hypothesized that an optimal ICS for thoracoscopic-assisted lung lobectomy in cats could be identified for each lung lobe.

Materials and Methods

Sample

Cadavers of 8 mature cats were obtained from a humane society for use in the study. Cats had been euthanized for reasons unrelated to disease of the thoracic cavity. All procedures were performed at the Comparative Clinical Research Facility of the University of Guelph.

Thoracoscopic-assisted pulmonary surgery for simulated lung lobectomy

All procedures were performed by 1 investigator (JES). Cadavers were placed in right lateral recumbency, and the thorax was classified into 3 regions (dorsal, middle, and ventral; one-third of the thorax for each region). A 6-mm thoracoscopic cannulaa was inserted in the middle third of ICS 9, and a 5-mm × 29-cm, 30°, rigid telescopeb was inserted into the thorax for initial evaluation of the thoracic cavity. After the initial evaluation was completed, the telescope was removed, a 5-cm minithoracotomy incision was made in the middle third of ICS 4 on the left side, and a wound retractor devicec was inserted.

The left cranial lung lobe (both the cranial and caudal subsegments) was carefully digitally exteriorized through the wound retractor device, and a 30 −mm thoracoabdominal staplerd was applied at the hilus of the exteriorized portion of the lung to simulate a lobectomy (Figure 1). Distance from the stapler anvil to the hilus was measured, and the stapler then was removed (no staples were placed for any of the simulated lobectomies).

Figure 1—
Figure 1—

Photograph of a cat cadaver positioned in right lateral recumbency with a minithoracotomy incision at ICS 4 on the left side. A wound retractor device is placed in the minithoracotomy incision, and a thoracoscopic port is placed at ICS 9. The left cranial lung lobe is exteriorized through the wound retractor device, and a thoracoabdominal stapling device is placed extracorporeally.

Citation: American Journal of Veterinary Research 80, 11; 10.2460/ajvr.80.11.1050

The left caudal lung lobe was partially exteriorized through the wound retractor device, the telescope was reinserted through the cannula in ICS 9, and the pulmonary ligament was sectioned by use of a combined intracorporeal and extracorporeal technique. Standard Metzenbaum scissors were inserted through the wound retractor device and used to section the left aspect of the pulmonary ligament via thoracoscopic visual assistance. This enabled complete exteriorization of the left caudal lung lobe. The thoracoabdominal stapler was applied, and the distance from the stapler anvil to the hilus was measured for the left cranial lung lobe. Procedures were repeated at ICS 5 through 7 on the left side for both the left cranial and left caudal lung lobes.

Cadavers were then placed in left lateral recumbency. Procedures were repeated at ICS 4 through 8 on the right side for the right cranial, right middle, right caudal, and accessory lung lobes. The right aspect of the pulmonary ligament was sectioned through ICS 5 to assist with exteriorization of the accessory and right caudal lung lobes.

Thus, each of the 8 cat cadavers underwent minithoracotomy on ICS 4 through 7 on the left side and ICS 4 through 8 on the right side. All lung lobectomies were simulated; an actual lobectomy was not performed on any of the cadavers.

Statistical analysis

Continuous data were assessed for normality by use of the Shapiro-Wilk test. Nonparametric data sets were summarized as median and interquartile (25th to 75th percentile) range. Effect of ICS on distance from the stapler anvil to the hilus of each lung lobe was assessed by use of a Kruskal-Wallis rank sum test. When a significant overall difference was detected, comparisons between spaces (eg, ICS 4 vs ICS 5) were performed by use of a Wilcoxon test. Values were considered significant at P < 0.05.

Results

Median weight of cats was 3.5 kg (interquartile [25th to 75th percentile] range, 3 to 4 kg). For thoracoscopic-assisted lobectomy of the left cranial lung lobe, median distance from the stapler anvil to the pulmonary hilus did not differ significantly (P = 0.163) at ICS 4, 5, or 6 on the left side (Figure 2). For thoracoscopic-assisted lobectomy of the left caudal lung lobe, median distance from the stapler anvil to the pulmonary hilus was significantly (P = 0.009) less when performed at ICS 5 and 6 on the left side, compared with the distance when performed at ICS 4 and 7 on the left side. For both the left cranial and caudal lung lobes, distance from the stapler to the hilus was less, but not significantly so, when thoracoscopic-assisted pulmonary surgery for lung lobectomy was performed at ICS 5.

Figure 2—
Figure 2—

Median (interquartile [25th to 75th percentile] range) distance from the stapler anvil to the hilus of a lung lobe of 8 cat cadavers during simulated lobectomy of the left cranial and left caudal lung lobes performed at ICS 4 (gray bars), 5 (black bars), 6 (horizontal-striped bars), and 7 (diagonal-striped bars) on the left side and of the right cranial, right middle, right caudal, and accessory lung lobes performed at ICS 4, 5, 6, 7, and 8 (vertical-striped bars) on the right side. *Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 4 on the same side. †Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 7 on the same side. ‡Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 6 on the same side. §Within a lung lobe, the median value differs significantly (P < 0.05) from the median value for ICS 8 on the same side.

Citation: American Journal of Veterinary Research 80, 11; 10.2460/ajvr.80.11.1050

Median distance from the stapler anvil to the pulmonary hilus was significantly less for thoracoscopic-assisted lobectomy of the right cranial lung lobe performed at ICS 4 (P = 0.015) and 5 (P = 0.015) on the right side than when it was performed at ICS 7 on the right side. No significant difference was detected when thoracoscopic-assisted lobectomy of the right cranial lung lobe was performed at ICS 6 on the right side, compared with results for ICS 4, 5, and 7 on the right side (Figure 2).

Median distance from the stapler anvil to the pulmonary hilus was significantly less for thoracoscopic-assisted lobectomy of the right middle lung lobe performed at ICS 4 (P = 0.036) and 5 (P = 0.031) on the right side than for lobectomy performed at ICS 7 on the right side. Distance from the stapler anvil to the pulmonary hilus was significantly (P = 0.039) less for thoracoscopic-assisted lobectomy of the right middle lung lobe performed at ICS 5 on the right side than for lobectomy performed at ICS 6 on the right side. However, there was no significant (P = 0.859) difference in the distance from the stapler anvil to the pulmonary hilus for thoracoscopic-assisted lobectomy of the right middle lung lobe performed at ICS 6 and 7 on the right side (Figure 2).

Median distance from the stapler anvil to the pulmonary hilus was significantly less for thoracoscopic-assisted lobectomy of the right caudal lung lobe performed at ICS 5 (P = 0.001) and 6 (P = 0.003) on the right side than for lobectomy performed at ICS 8 on the right side. Distance from the stapler anvil to the pulmonary hilus was significantly (P = 0.005) less for thoracoscopic-assisted lobectomy of the right caudal lung lobe performed at ICS 5 on the right side than for lobectomy performed at ICS 7 on the right side. Distance from the stapler anvil to the pulmonary hilus was significantly (P = 0.045) less for thoracoscopic-assisted lobectomy of the right caudal lung lobe performed at ICS 7 on the right side than for lobectomy performed at ICS 8 on the right side (Figure 2). Statistical analysis for ICS 4 was not performed because it was not possible to exteriorize the right caudal lung lobe to allow a simulated lobectomy at this location in any of the cadavers.

Median distance from the stapler anvil to the pulmonary hilus was significantly less for thoracoscopic-assisted lobectomy of the accessory lung lobe performed at ICS 5 (P = 0.002) and 6 (P = 0.005) on the right side than for lobectomy performed at ICS 8 on the right side. No significant difference in the distance from the stapler anvil to the pulmonary hilus was detected for thoracoscopic-assisted lobectomy of the accessory lung lobe performed at ICS 7 on the right side, compared with the distance for lobectomy performed at ICS 5, 6, and 8 on the right side (Figure 2). Statistical analysis for ICS 4 was not performed because it was not possible to exteriorize the accessory lung lobe to allow a simulated lobectomy at this location in any of the cadavers.

Discussion

Results for the study reported here may provide surgeons with information on the optimal ICS to use when performing thoracoscopic-assisted pulmonary surgery for lung lobectomy in cats. Based on these data, it is recommended that a thoracoscopic-assisted pulmonary surgery approach be performed at ICS 4 or 5 in cats undergoing thoracoscopic-assisted pulmonary surgery for lobectomy of the right or left cranial and right middle lung lobes and at ICS 5 or 6 in cats undergoing thoracoscopic-assisted pulmonary surgery for lobectomy of the left caudal, right caudal, and accessory lung lobes.

No significant difference in the distance from the stapler anvil to the pulmonary hilus was detected when thoracoscopic-assisted pulmonary surgery was used to perform a simulated lung lobectomy of the left cranial lung lobe at ICS 4, 5, or 6 on the left side; the lack of a significant difference was likely attributable to a type 2 error. A thoracoscopic-assisted lung lobectomy performed in cats typically resulted in a shorter median distance from the stapler anvil to the pulmonary hilus for the left caudal, right caudal, and accessory lung lobes when performed at ICS 5 and 6, compared with lobectomies performed at ICS 4, 7, and 8. These results were not surprising because ICS 5 and 6 are the recommended location for lobectomy of the caudal lung lobes via open thoracotomy in cats.13 To our knowledge, the ideal ICS for lobectomy of the accessory lung lobe in cats has not been described in the veterinary literature. However, a recent study14 of canine cadavers revealed that ICS 5 and 6 on the right side may be optimal locations for thoracoscopic-assisted lobectomy of the accessory lung lobe in dogs. Before the accessory lung lobe can be removed, it must be manipulated medially and dorsally over the vena cava,15 and the pulmonary ligament must be transected; based on the results of this study, it is suggested that both of these procedures were best achieved at ICS 5 or 6 in the cat cadavers in the present study.

Thoracoscopic-assisted lung lobectomy performed at ICS 4 or 5 on the right side resulted in a significantly shorter median distance from the stapler anvil to the pulmonary hilus for the right cranial and right middle lung lobes. These results were not surprising because ICS 4 and 5 are recommended for use in open thoracotomies to access the right cranial and right middle lung lobes.13

Similar to the technique described in the aforementioned canine cadaver study,14 a combined intracorporeal and extracorporeal technique was used for resection of the pulmonary ligament to facilitate lobectomy of the left caudal, right caudal, and accessory lung lobes in the cat cadavers of the present study. Once each lung lobe was partially exteriorized through the wound retractor device, the telescope was reinserted into the thorax and the pulmonary ligament visually identified. By use of endoscopic guidance, standard Metzenbaum scissors were carefully inserted into the thorax through the wound retractor device and used to resect the pulmonary ligament. This technique was subjectively easy to perform, avoided iatrogenic damage to vessels and pulmonary parenchyma, and did not require specialized equipment. The present study was performed on cat cadavers; thus, there was no pulmonary ventilation that could have obscured visual identification of the pulmonary ligament. The authors believe that because the left and right and accessory lung lobes will be partially exteriorized through the wound retractor device, visual identification of the pulmonary ligament will be adequate; however, further evaluation in clinical cases is warranted.

A wound retractor device was inserted into the minithoracotomy incision. Such devices offer multiple benefits, including a reduction in the signs of pain attributable to spreading of the ribs, less pressure on intercostal nerves, and potential protection against neoplastic spread.16,17 An extra small wound retractor device that opened to 2 to 4 cm was used in the cat cadavers of the study reported here. Mild to moderate tearing of the intercostal muscle fibers could be seen in smaller cadavers as the wound retractor device was tightened. It is unknown whether this tearing was attributable to the fact the tissues had been frozen or to opening of the wound retractor device. Caution should be exercised when placing a wound retractor device in clinically affected animals to prevent muscle tearing, and tightening the wound retractor device to less-than-full tension should be considered. Investigators of another study12 made a smaller thoracotomy incision (3 cm) but used a similar-sized wound retractor devicee that also opened to 2 to 4 cm; however, intercostal muscle tearing was not reported in that study.12 This suggested that the muscle tearing observed in the cat cadavers of the present study may have been attributable to postmortem artifact.

A 30-mm stapling device was used for simulated thoracoscopic-assisted lobectomy in the study reported here. This device has been commonly used by veterinary surgeons for several open thoracic and abdominal surgical procedures, including lung lobectomy.13,14 The stapler anvil was placed at an angle into the 5-cm-long minithoracotomy incision to allow application of the stapler as near as possible to the pulmonary hilus. In a recent study12 on thoracoscopic-assisted lung lobectomy in cat cadavers, investigators described the use of a 55-mm thoracoabdominal stapler.f Mean distance of the stapler anvil to the pulmonary hilus of the cranial lung lobe when approached via ICS 4 in that study12 was greater (4 to 5 mm greater) than the distance in the cat cadavers of the present study. The greater distance from the stapler anvil to the pulmonary hilus in that study12 may have been a result of the use of the 55-mm thoracoabdominal stapler for lung lobectomy. The length of the stapler anvil in that study12 (55 mm) was greater than the length of the minithoracotomy incision (3 cm), which may have limited the ability of those investigators to position the stapler anvil into the thoracic cavity through the wound retractor device. We chose to use a slightly longer minithoracotomy incision (5 cm) than has been described for other studies1,12 to mimic clinical situations whereby pulmonary tumors of < 5 cm could be removed. Minithoracotomy incisions of 3 cm have been used in cats and dogs with pulmonary neoplasia1; however, these incisions had to be extended to facilitate removal of masses that had a median size of 4.7 cm.1 Even with the use of a 30-mm thoracoabdominal stapler and longer minithoracotomy incision (5 cm), it was subjectively more difficult to position the stapler anvil into the thoracic cavity in the smaller cat cadavers of the present study. This emphasized the importance of finding the optimal ICS for lung lobectomy.

When lung lobectomy is performed because of pulmonary neoplasia, samples of the tracheobronchial lymph nodes are commonly collected because evaluation of those lymph nodes can be used as a prognostic indicator for survival time.18 Assessment and removal of tracheobronchial lymph nodes by use of a thoracoscopic-assisted pulmonary surgery technique was not assessed in the study reported here. Further evaluation of a thoracoscopic-assisted pulmonary surgery technique for collection of tracheobronchial lymph nodes is required.

Limitations of the present study included the use of cadavers, which may not mimic clinical situations. Mild tearing of the intercostal muscles was noted in the cat cadavers when the wound retractor device was completely opened. This may have artificially increased the width of the intercostal incision and allowed improved access to the pulmonary hilus. Each cadaver was subjected to multiple thoracotomies, and the effect of previous thoracotomy incisions on access to the hilus is unknown; however, such previous incisions may have contributed to increased mobility of the lung tissues. Additionally, the impact of ventilation was not evaluated. Another limitation included the use of cat cadavers that did not have pulmonary pathological conditions, which would preclude direct translation of the information to patients with pulmonary neoplasia. Tumors between 2.9 and 11.4 cm have been successfully removed from dogs and cats by use of a thoracoscopic-assisted pulmonary surgery technique, with the minithoracotomy incision extended to > 3 cm to allow for removal of large masses.1 Data in that study1 were not differentiated between species, and objective comparison to lung lobectomy via thoracotomy was not made. However, the authors of that study1 believed that thoracoscopic-assisted pulmonary surgery resulted in good cosmesis and that postoperative comfort was improved, compared with results for traditional open surgery techniques. Ideal oncological candidates and the impact of mass size are unknown; thus, further research is warranted.

Data provided in the study reported here suggested that ICS 5 may be the optimal location for thoracotomy during open and minimally invasive approaches for hilar lung lobectomy in cats. Additional research is required in cats with primary pulmonary neoplasia that undergo thoracoscopic-assisted lung lobectomy.

Acknowledgments

The authors declare there were no conflicts of interest.

ABBREVIATIONS

ICS

Intercostal space

Footnotes

a.

Thoracoport, Medtronic, Mansfield, Mass.

b.

Laparoscope, Karl Storz Endoscopy, Goleta, Calif.

c.

SurgiSleeve extra small, Medtronic, Mansfield, Mass.

d.

TA30V3, Medtronic, Mansfield, Mass.

e.

Alexis wound retractor extra small, Applied Medical Resources, Rancho Santa Margarita, Calif.

f.

TA55, Medtronic, Mansfield, Mass.

References

  • 1. Wormser C, Singhal S, Holt DE, et al. Thoracoscopic-assisted pulmonary surgery for partial and complete lung lobectomy. J Am Vet Med Assoc 2014;245:10361041.

    • Search Google Scholar
    • Export Citation
  • 2. Haimel G, Liehmann L, Dupré G. Thoracoscopic en bloc thoracic duct sealing and partial pericardectomy for the treatment of chylothorax in two cats. J Feline Med Surg 2012;14:928931.

    • Search Google Scholar
    • Export Citation
  • 3. Plesman R, Johnson M, Rurak S, et al. Thoracoscopic correction of a congenital persistent right aortic arch in a young cat. Can Vet J 2011;52:11231128.

    • Search Google Scholar
    • Export Citation
  • 4. Kovak JR, Ludwig LL, Bergman PJ, et al. Use of thoracoscopy to determine the etiology of pleural effusion in dogs and cats: 18 cases (1998–2001). J Am Vet Med Assoc 2002;221:990994.

    • Search Google Scholar
    • Export Citation
  • 5. Walsh PJ, Remedios AM, Ferguson JF, et al. Thoracoscopic versus open partial pericardectomy in dogs: comparison of postoperative pain and morbidity. Vet Surg 1999;28:472479.

    • Search Google Scholar
    • Export Citation
  • 6. Bleakley S, Duncan C, Monnet E. Thoracoscopic lung lobectomy for primary lung tumors in 13 dogs. Vet Surg 2015;44:10291035.

  • 7. Peláez MJ, Jolliffe C. Thoracoscopic foreign body removal and right middle lung lobectomy to treat pyothorax in a dog. J Small Anim Pract 2012;53:240244.

    • Search Google Scholar
    • Export Citation
  • 8. Dupre G. Thoracoscopic pericardial window and subtotal pericardectomy in dogs and cats. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;294301.

    • Search Google Scholar
    • Export Citation
  • 9. Monnet E. Thoracoscopic lung biopsy and lung lobectomy. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;287293.

    • Search Google Scholar
    • Export Citation
  • 10. Pascoe PJ, Mayhew PD. Anesthesia for thoracoscopy. In: Fransson BA, Mayhew PD, eds. Small animal laparoscopy and thoracoscopy. Ames, Iowa: Wiley Blackwell, 2015;255270.

    • Search Google Scholar
    • Export Citation
  • 11. Radlinsky M. Thoracoscopy in the cat: an up-and-coming diagnostic and therapeutic procedure. J Feline Med Surg 2014;16:2733.

  • 12. Nylund AM, Höglund OV, Fransson BA. Thoracoscopic-assisted lung lobectomy in cat cadavers using a resorbable self-locking ligation device. Vet Surg 2019;48:563569.

    • Search Google Scholar
    • Export Citation
  • 13. Monnet E. Lungs. In: Johnston SA, Tobias KM, eds. Veterinary surgery: small animal. 2nd ed. St Louis: Elsevier Inc, 2018:19832002.

  • 14. Singh A, Scott J, Case JB, et al. Optimization of surgical approach for thoracoscopic-assisted pulmonary surgery in dogs. Vet Surg 2019;48:O99O104.

    • Search Google Scholar
    • Export Citation
  • 15. Shamir S, Mayhew PD, Zwingenberger A, et al. Treatment of intrathoracic grass awn migration with video-assisted thoracic surgery in two dogs. J Am Vet Med Assoc 2016;249:214220.

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    • Export Citation
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Contributor Notes

Address correspondence to Dr. Singh (amsingh@uoguelph.ca).