Video-Assisted Thoracoscopic Resection of a Noninvasive Thymoma in a Cat with Myasthenia Gravis Using Low-Pressure Carbon Dioxide Insufflation

Outcome of video-assisted thoracoscopic treatment of idiopathic chylothorax in 15 cats

OBJECTIVE

To evaluate the outcomes and complications of video-assisted thoracoscopic (VATS) treatment of chylothorax in cats.

STUDY DESIGN

Multi-institutional retrospective study.

ANIMALS

Fifteen client-owned cats.

METHODS

The medical records of cats undergoing thoracoscopic thoracic duct ligation (TDL) for treatment of idiopathic chylothorax were reviewed. Cats undergoing additional procedures including thoracoscopic pericardectomy and/or laparoscopic cisterna chyli ablation (CCA)_were included. Follow up was obtained through communication with the referring veterinarian or owner.

RESULTS

All cats underwent thoracoscopic TDL. Thirteen cats underwent simultaneous pericardectomy and two cats underwent laparoscopic CCA without pericardectomy. Conversion from a thoracoscopic to open approach was necessary in 2/15 (13%) of thoracic duct ligations and 1/11 (9%) of pericardectomies. The most common postoperative complication was persistent pleural effusion in five cats (33%). Four of 15 cats (27%) died or were euthanized prior to hospital discharge following surgery. Recurrence of effusion occurred in 1/7 (14%) of cats that sustained resolution of the effusion at the time of surgery with a median follow up of 8 months. The overall mortality attributed to chylothorax was 47%.

CONCLUSION

Thoracoscopic treatment of idiopathic chylothorax resulted in a low incidence of intraoperative complications or conversion in the study population; however, mortality related to feline idiopathic chylothorax remained high.

CLINICAL SIGNIFICANCE

While VATS treatment of idiopathic chylothorax is technically feasible, further consideration of the underlying pathology and current treatment algorithm is needed to improve outcomes as this remains a frustrating disease to treat in the feline population.

CT imaging features of canine thymomas

Canine thymomas have been evaluated based on clinical features, treatment options, surgical excision, and outcomes with limited information on specific CT features. The objective of this retrospective, descriptive, cross-sectional study was to describe the CT characteristics of confirmed thymomas and to compare these imaging features to outcome. A total of 22 dogs met the inclusion criteria of histologically confirmed thymomas with concurrent CT imaging. Tumor size varied widely ranging from small and well-circumscribed to large and invasive. Delayed-phase, contrast-enhanced CT studies were best for determining the degree of contrast enhancement in tumors. Of these, 19 of 22 masses had heterogeneous enhancement and three of 22 masses had homogeneous enhancement. Vascular invasion was present in seven of 22 cases. Larger tumors were associated with vascular invasion (height: P = .04; width and volume: P = .02). On precontrast CT, larger tumors (16/21) were heterogeneous and cystic, with smaller tumors (5/21) being more homogeneous (all values P < .05). A larger size was associated with recurrence in fully resected masses (height: P = .03), but not a shorter outcome (P > .3 for all size dimensions). Postoperative complications and incomplete tumor resection were associated with shorter outcome (both values P < .01). Metastasis was confirmed in four cases. There were six cases with lymphadenopathy noted on CT; five of the six cases did not have evidence of metastasis. Larger tumors were more likely to be cystic and associated with vascular invasion.

Cardiorespiratory effects of variable pressure thoracic insufflation in cats undergoing video-assisted thoracic surgery

OBJECTIVE

To evaluate the effects of intrathoracic insufflation on cardiorespiratory variables and working space in cats undergoing video-assisted thoracic surgery.

STUDY DESIGN

Prospective randomized study.

ANIMALS

Six healthy cats.

METHODS

Cats were anesthetized using a standardized protocol. A Swan-Ganz catheter was positioned in the pulmonary artery under fluoroscopic guidance for measurement of cardiac output. Intrathoracic pressures (ITP) of 0 (baseline), 3, and 5 mm Hg were induced with CO₂ and maintained for 30 minutes. Statistical comparison of cardiorespiratory variables was performed. After the procedures, all cats were recovered from anesthesia. Videos of thoracic working space at each ITP level were scored in a blinded fashion by 3 board-certified surgeons using a numerical scale from 0-10.

RESULTS

All cats tolerated insufflation with 3 and 5 mm Hg for 30 minutes without oxygen desaturation, although ventilatory levels had to be increased substantially to maintain eucapnia and oxygenation. Cardiac index was not significantly different from baseline after 30 minutes at 3 mm Hg but was significantly lower after 30 minutes at 5 mm Hg compared with 3 mm Hg. Oxygen delivery was unaffected by 3 or 5 mm Hg compared with baseline. Scores for working space increased between baseline and 3 and 5 mm Hg but were not different between 3 and 5 mm Hg.

CONCLUSION

CO₂ insufflation to 5 mm Hg seems well tolerated in healthy cats, provided ventilatory settings are substantially increased as ITP increases.

CLINICAL SIGNIFICANCE

Thoracic CO₂ insufflation of 3 mm Hg in cats during video-assisted thoracic surgery is associated with less hemodynamic perturbation than 5 mm Hg insufflation and may provide the benefit of improved working space compared with baseline.