Lung surgery
Lung surgery is a type of thoracic surgery involving the repair or removal of lung tissue, and can be used to treat a variety of conditions ranging from lung cancer to pulmonary hypertension. Common operations include anatomic and nonanatomic resections, pleurodesis and lung transplants. Though records of lung surgery date back to the Classical Age, new techniques such as VATS continue to be developed.
History
The first written records of lung surgery were provided by Hippocrates, where he described a treatment for thoracic empyema by means of drainage. Thoracic procedures became more viable with the advent of positive pressure ventilation, introduced by Samuel Meltzer in 1909. This technique enables surgeons to conduct open chest procedures without risking hypoxia, significantly decreasing patient mortality and is presently used in conjunction with double-lumen endotracheal intubation to isolate the ventilation of the affected lung during surgery. The 20th century saw further innovation of new procedures, such as the first-ever pneumonectomy performed by Evarts Graham in 1933. A breakthrough in minimally invasive lung surgery was also achieved in the form of thoracoscopy, developed by Hans Christian Jacobaeus in 1910 as a method to diagnose tuberculosis. Thoracoscopy was later used by surgeons to perform chest operations without open thoracotomy. However, the latter remains a widely used method to access the pleural cavity.Obsolete procedures
Before the advent of tuberculosis chemotherapy in the 1940s, the disease was treated via collapse therapy. This involved the creation of an artificial pneumothorax, aimed at resting the infected lung to limit infection spread and accelerate healing. The traumatic nature of collapse therapy and the discovery of antituberculosis drugs has rendered the former obsolete.Types of lung diseases
Lung cancer
Lung cancer can be classified into two main types: non-small cell lung cancer and small cell lung cancer. NSCLC, the most common of the two types, is a group of cancers including squamous cell carcinoma, adenocarcinoma and large cell carcinoma. SCLC is highly aggressive and consists of small ovoid cells. Surgical resection is used curatively in stage I-III NSCLC and palliatively in stage IV.Pneumothorax
A pneumothorax, also known as a collapsed lung, is a collection of air outside the lung in the pleural cavity. Depending on etiology, a pneumothorax is classified as spontaneous, traumatic and iatrogenic. A spontaneous pneumothorax is further classified as primary and secondary, with the former occurring in individuals with no clinical lung disease and the latter occurring as a complication of preexisting lung disease.Chronic obstructive pulmonary disease
is a group of diseases that results in airflow blockage and therefore cause breathing-related issues. COPD includes emphysema as well as chronic bronchitis.Cystic fibrosis
is a genetic disease, caused by a mutation that results in defects in movement of salt and water in and out of cells which can cause sticky mucus in the body's tubes and passageways such as in the lungs.Pulmonary hypertension
occurs as a result of excess pressure in the blood vessels from the heart to the lungs. An increased amount of muscle in the walls of the blood vessels to the lung is prominent in cases with pulmonary hypertension. Although there are treatments such as oxygen therapy and medicine that is given to reduce swelling, lung transplantation may be necessary in some extreme cases.Idiopathic pulmonary fibrosis
causes the lungs to become scarred which results in a difficulty in breathing. The causes are of this disease is still not fully known, however, prevention methods include self-care such as stopping smoking and exercising. Medicines such as pirfenidone and nintedanib are also commonly used in order to reduce the rate of scarring in the lungs. Lung transplantation is effective in certain cases, however this depends on the availability of healthy donor lungs.Anatomic resections
Anatomic resections refer to procedures where a section of the lung is removed with respect to lobar or segmental anatomy. These include pneumonectomies, lobectomies and segmentectomies and are commonly used for the treatment of NSCLC. Preoperative evaluations for resections include cancer staging via a chest CT scan and PET scan, followed by assessments of pulmonary reserve volume and cardiac function to determine the amount of lung tissue that can be safely removed without developing pulmonary insufficiency. Following tissue removal, the resultant bronchial stumps are pressurised under water to check for air leaks before the resection is deemed complete.Pneumonectomy
A pneumonectomy is the surgical removal of an entire lung. Due to the high morbidity and mortality of the procedure, its viability for treating lung cancer is a subject of debate. However, pneumonectomies are still used for lung carcinomas that are large and centrally located or have invaded the interlobar fissures. Another indication for the use this procedure is lung destruction due to chronic infections.During a pneumonectomy, the pleural cavity is accessed through a thoracotomy. With direct access to the tumour, the need for pneumonectomy is reassessed. After surgeons decide to proceed with the procedure, the hilar structures are dissected sequentially. The pulmonary artery, then the pulmonary veins, are divided via stapling. Next, the main bronchus is divided using a scalpel and the lung is removed from the pleural cavity. The bronchial stump is subsequently closed by polyglactin sutures. Finally, mediastinal lymph nodes are dissected.
Lobectomy
A lobectomy is the surgical removal of one of the five lung lobes. Lobectomies are the most common type of lung surgery and the standard operation for most NSCLC patients. Though specific surgical techniques vary for each lobe, the general workflow is identical. The lobe to be resected is first visualized through thoracotomy or thoracoscopy. Next, the surrounding lymph nodes are harvested to check for metastasis. After confirmation that no metastasis has taken place, the vasculature of the lobe is controlled by blood vessel division using a stapler. Stapling is also used to divide the lobar bronchus and subsequently separate the lobe along the lung fissure. After the lobe is removed, lymph node dissection is completed.Specific considerations exist for certain lobes. Right middle lobectomies are not usually carried out alone and are instead part of a bilobectomy alongside a right upper or lower lobectomy. Left upper lobectomies require additional caution to avoid arterial branches from the fissure and proximal pulmonary artery. Another risk is the proximity of the recurrent laryngeal nerve to the upper mediastinal lymph nodes, which increases its risk of injury during lymph node dissection. Thus, a swallowing study is required if nerve damage is suspected postoperatively.
Sleeve lobectomy
A sleeve lobectomy is a lobectomy that is coupled with the removal of a part of the main bronchus. The ends of the bronchus are then rejoined to reattach any remaining lung lobes. This procedure is performed in lieu of pneumonectomy when surgeons determine the removal of the entire lung to be unnecessary for centrally located tumours.Segmentectomy
are the surgical removal of bronchopulmonary segments and often involve the removal of two adjacent segments. The pulmonary arterial branches to the segments are first identified then divided. Next, stapling is used to divide the segmental bronchi and separate the segments from the lung. Compared to lobectomies, this procedure has higher survivability for stage 1A patients with tumours ≤ 2 cm in diameter.Non-anatomic resections
Non-anatomic resections refer to the removal of lung tissue without respect to lobar or segmental anatomy. They can be used to treat a variety of lung diseases such as NSCLC and tuberculosis.Wedge resection
A wedge resection is the non-anatomic removal of a triangular-shaped piece of tissue from the lungs. The utility of wedge resection in NSCLC is disputed. Wedge resection is currently used in NSCLC patients with low pulmonary function, or for pulmonary tuberculosis patients with multiple lesions which do not respect intersegmental boundaries.Bleb resection
A bleb resection is the surgical removal of one or more blebs, small collections of air between the lung and visceral pleura. Blebs may combine to form larger cysts named bullae. The rupture of blebs or bullae results in air leaking into the pleural space, causing a spontaneous pneumothorax. In most cases, patients will be unaware of blebs until they are detected by CT scans or cause noticeable symptoms such as chest pain.Bleb resections may be done via mini-thoracotomy or thoracoscopy. After inspection of the chest cavity, identified blebs are removed via dissection and stapling. To prevent future bleb formation, this procedure is often accompanied by pleurodesis.