Randomized controlled study to investigate the role of intraoperative vagal nerve block for preventing the postoperative cough in patients who received the pulmonary resection for lung cancer

The standard treatments for early primary lung cancer are surgical treatments (lobectomy and lymph node resection). The usual mortality rate of lung cancer surgery is 1-2%, and the incidence of complications is reported to be about 20%. In addition to these deaths and complications, there are frequent sequelae such as reduction of pulmonary function reduction and cough. According to a cross section study of 240 patients who underwent lung cancer surgery, about 30% of patients complained of cough after surgery for one year after surgery, and 50% of patients complained of cough after one year. After the pulmonary resection of lung cancer, chronic coughs are the main cause of lowering the quality of life of patients after lung surgery. Several studies have reported the risk factors of cough after lung cancer surgery, and it is known that there is a relationship between mediastinal lymph node resection and accompanying gastric-esophageal gastric acid reflux.

According to anatomy and physiology studies of coughs, coughing occurs due to stimulation of vagus nerves, which is a type of reflex to protect the respiratory tract from harmful stimuli from the outside. Cough cough is known to occur when c-fibers are stimulated, especially at the end of the vagus nerve. Cough reflex-related circuits from c-fiber to brain are generated, and then coughing is reported in smaller stimuli. The end of the vagus nerves in the bronchial area can be damaged by the mediastinal lymph nodes dissection during lung cancer surgery and it can lead to c-fiber stimulation and finally form the nerve circuit which can lead to chronic cough.

Recently, awake pulmonary resection (awakening surgery) has been performed in several countries. Normally, sleep anesthesia gas itself is depleted of vagus nerve function and does not cause cough reflex during surgery, but when operated in a waking state, coughing caused by vagus nerve stimulation may occur and dangerous situations may occur during surgery, so it is reported that vagus nerve block is performed at the start of surgery. These vagus nerve blocks are known to prevent cough reflex during awakening surgery and enable surgery to be performed stably. However, it is not yet known whether these vagus nerve block can reduce acute and chronic cough after surgery. In this study, we investigated whether vagus nerve block during surgery could reduce coughing after surgery in patients who underwent general anesthesia lung cancer surgery.

Inclusion Criteria:

• American Society of Anesthesiologists' physical status class Ⅲ
• Diagnosed with non-small cell lung cancer with clinical stage of I-IIIA
• Planned to undergo segmentectomy or lobectomy with mediastinal lymph node dissection

Exclusion Criteria:

• chronic cough symptoms before surgery; a chronic cough (a cough lasting more than eight weeks)
• chemotherapy or chemoradiotherapy prior to surgery
• current smoker (patient should quit smoking at least 2 weeks before surgery)
• previously diagnosed with airway disease prior to surgery
• previously diagnosed with asthma prior to surgery
• patients with nervous system defects or psychiatric problems
• patients with severe cardiovascular disease, hepatological, or renal failure