VIDEO ASSISTED THORACOSCOPIC SURGERY

VIDEO ASSISTED THORACOSCOPIC SURGERY

Principles of thoracoscopic surgery

The minimal requirement for VAT are: rigid telescope, a light source with cable, a camera and an image processor.

The optimal devices are: slave monitor, semiflexible telescope and a video recorder.

• VATS require high light output power as blood is in the operative field absorb 50% of the light.
• The access site must be placed at sufficient distance from the target pathology to allow for adequate room.
• The thoracic is rigid and the access sites are limited to the intercostals space.
• Single lung anesthesia is necessary to deflate the lung’
• All movement should be under direct vision to prevent damage to surrounding tissue.
• The surgeon should be able to handle complication and converting to open procedures.
• Specific instruments include stapling device, laser, dissectors and retractors.

Indications

The common indications are:

1.       Cancer staging

2.       Diagnosis of pleural disease

3.       Management of persistent pneumothorax, retained hemothorax, infected pleural space    including empyema

4.       Pericardial drainage

5.       Thoracic sympathectomy
 with surgical advances other indications have been added to the list:

·         Thoracic duct ligation

·         Removal of thoracic cyst

·         Vagotomy

·         Lobar resection

·         Esophageal surgery

Contraindications

1.       Pleural symphysis caused by previous thoracic surgery or pleurodesis

2.       Bleeding disorders

3.       End stage pulmonary fibrosis

4.       Respiratory insufficiency and hempdynamic instability

Advantages

1.       Shorter length of hospital stay

2.       Less postoperative pain

3.       Preserved pulmonary function

4.       Superior cosmotic result

5.       Shorter recovery time

Anesthetic management of VATS
Preoperative evaluation

A thorough history and physical exam with special attention to the cardiorespiratory status is necessary for all patients. Routine lab investigation include full blood count, electrolyte levels, ECG, chest radiograph and CT scan help to make diagnosis and identify potential problems. Spirometry tests include FVC

                                                                                                FEV₁

                                                                                                FEV₁ // FVC

Preoperative optimization of respiratory function is achieved by bronchodilator, cessation of smoking, incentive spirometry and physiotherapy.

Intraoperative management

The goals of anesthesia include maintaining stable cardiovascular function, optimizing oxygenation and ventilation, minimizing airway reactivity and  preventing respiratory depression in the postoperative period.

Monitoring

In addition to standard monitoring techniques, invasive arterial pressure and central venous pressure monitoring may be needed in patient with limited cardio-respiratory reserve.

Anesthetic techniques

Thoracoscopic surgery has been performed under local, regional or general anesthesia

-          General anesthesia is usually induces with an IV agent such as propofol or thiopentone and maintained with inahalational agent in air/O2 misture

N2O is preferably avoided because of the risk of expansion of air filled spaces.

Advantage of inhalation agents to be mentioned

Narcotic analgesia attenuate stress response, reduce requirement of inhalational agent  and produce analgesia

-          Most VAT require patient to be placed in lateral decubitus position.

-          One lung anesthesia is required

-          Postoperative analgesia strategies include oral opioids, PCA, local anesthetic infiltration, intercostals block, paravertebral block and epidural analgesia.

-          Post op care

-          Carbon dioxide insufflations

It may be used to accelerate lung deflation.

Rapid or excessive insufflations of the gas may cause mediastinal shift resulting in hemodynamic instability, bradycardia, hypertension, hypoxia and surgical emphysema.

Gas flow is restricted to 2L/m with the pressure limited to 10mmHG

Complications

o   hypoxemia  caused by v/p mismatch

o   Chest pain caused by thermal damage to the parietal pleura and the periosteum over the ribs.

o   Respiratory complication: sputum retention, atelectasis

o   bleeding due  to injury to blood vessels or lung perforation.