Minimally invasive thoracic surgery

Minimally invasive thoracic surgery

With the right instruments and approach, you can perform minimally invasive surgery in the thoracic cavity.

Eric Monnet, DVM, MD, PhD, DACVS, DECVS
Imagine exploring the thoracic cavity and performing surgical interventions without using an intercostal or a median sternotomy. This is possible when you perform thoracoscopy—a technique widely used in human thoracic and cardiac surgery. Minimally invasive video-assisted endoscopy and minimally invasive surgical instrumentation allow practitioners to perform diagnostic and advanced therapeutic procedures in the thoracic cavity.1 Thoracoscopy is indicated for exploration of the thoracic cavity, diagnosis of pleural effusion of unknown origin, and pericardial effusion.2-4 Biopsy of the pleural surface, lymph nodes, pericardium, and lungs can be performed during thoracic cavity exploration. Veterinary literature reports the use of thoracoscopy to perform lung lobectomies, ligate thoracic ducts, and correct persistent right aortic arches.5-8

What you will need The basic thoracoscopy equipment includes a surgical telescope (Figure 1), trocar-cannulas, a basic set of thoracoscopic surgical instruments, a light source, a video camera, and a video monitor (Table 1). Thoracoscopy doesn't require CO2 insufflation because the rib cage keeps the thoracic cavity expanded.

Telescopes Telescopes used for thoracoscopy are most commonly 5 mm in diameter and 30 cm long. This scope size works in a wide range of animals. Telescopes are available with different angles, and the forward-view 0-degree and the forward oblique 30-degree telescopes are most commonly used. The 0-degree telescope allows a natural field of view and a normal perspective to organ orientation. The 30- degree telescopes allow better visualization of areas in the thoracic cavity that are difficult to access. However, orientation and manipulation are more difficult with the angled scopes.

Cannulas Cannulas for thoracoscopy are either open or closed. Closed cannulas feature a valve that allows the veterinarian to create a controlled pneumothorax. They can potentially induce a tension pneumothorax during the procedure. Open cannulas create an open chest, as in a thoracotomy. Open cannulas are preferred for long surgical procedures because they reduce the risk for tension pneumothorax. Cannulas come in different diameters. The recommended diameter is 12 mm because most stapling equipment available for thoracoscopy is 10 mm in diameter.

Figure1. A 5-mm forward view telescope. The telescope is 30 cm long.
Instruments Numerous instruments are available for endoscopic exploration and surgery. The basic instrument set consists of grasping forceps, scissors, biopsy forceps, and a palpation probe. Forceps and scissors are insulated for electrocautery. Electrocautery can be used to cauterize small blood vessels during resection of the mediastinum or pericardium. For lung biopsies, pretied ligatures can be used, which eliminate the need for knot tying inside the thoracic cavity. Retractors are required to hold lungs away from the camera and obtain a clearer surgical field. Ligating small blood vessels in the mediastinum requires vascular clip applicators, which come in different sizes, and lung lobe resections necessitate the use of stapling equipment. The Endo GIA stapling device (Tyco Healthcare/Kendall Animal Health) comes in three lengths: 30, 45, and 60 mm. Staples come in lengths of 2.0, 2.5, 3.5, or 4.8 mm. Finally, suction and irrigation devices are available to aspirate blood during the procedure and lavage the surgical field and thoracic cavity.

As for equipment, two types are recommended for advanced surgical procedures using minimally invasive surgery: radiofrequency and ultrasound-based equipment. They provide fast, safe sealing of blood vessels without using suture materials. Radiofrequency equipment can safely seal an artery with a diameter of less than 7 mm. Ultrasound-based equipment allows the practitioner to cut through the tissue and seal the blood vessels. Vessels sealed using ultrasound technology should have a diameter of less than 3 mm.