【Animal Experiment】-Comparison of acute postoperative response and postoperative stress between video-assisted thoracoscopy and thoracotomy for small pig

  Background: Video-assisted thoracoscopic surgery (VATS) has been used as a diagnostic and treatment platform for performing various thoracic surgery operations. Including surgical lung biopsy, tumor staging, pneumothorax, pericardium and pericardial fenestration treatment. It has been recognized clinically that VATS is less painful and stress-free than traditional thoracotomy. Recent reports have also confirmed the safety and benefits of VATS. Animal models are usually similar to human models during surgical procedures. Experimental lung resection was performed on pigs. In dogs, the short-term effects of thoracoscopic lobectomy on primary lung tumors have been reported. Multiple studies of the VATS procedure on animals evaluated pressure parameters and postoperative outcomes. In order to further explore the impact of minimally invasive surgery on the acute phase response, stress response and postoperative pain, we designed a porcine clinical trial to compare the feasibility and safety of VATS and thoracotomy. Methods: Animals: 14 Bama miniature pigs with an average weight of 22.57±1.5 kg. The pigs are placed in a cage with a constant temperature (approximately 20°C), good light conditions (12 hours light/dark cycle), and they can eat freely. All animals undergo health assessment, physical examination and complete blood count before surgery. The animals were randomly divided into two groups. The first group underwent thoracoscopic pneumonectomy, and the second group underwent thoracoscopic pneumonectomy. Operation preparation: Determine the preoperative baseline physiological parameters, such as blood routine, heart rate (HR), rectal temperature, serum C-reactive protein (CRP), serum amyloid A (SAA), interleukin (T = 0)-6 (IL- 6) Cortisol concentration. After a 24-hour fast and a 2-hour fast, all pigs were subjected to the same general anesthesia and monitoring. Before surgery, each pig was injected with atropine sulfate (0.04mg/kg) and intramuscularly with cefazolin (20mg/kg). Xylazine (1 mg/kg) and ketamine hydrochloride (10 mg/kg) were injected intramuscularly to induce general anesthesia, and anesthesia was maintained through a 1.5-3% isoflurane oxygen tube. Use a ventilator and anesthesia machine to continue breathing (respiratory rate 12 breaths/minute, tidal volume 15-20 ml/kg, inhalation: expiration ratio = 1:2). All procedures use sterile instruments. The monitor monitors physiological parameters. The animal is placed on its back. The surgical site (from the collarbone to the last rib of the left chest, from the breastbone to the spine) is shaved and aseptically prepared for surgery. Place a heated blanket between the animal and the operating table. In the same environment, all operations are performed by the same trained veterinarian.

  Video-assisted chest surgery: Create two portals: Endoscopy portal (Portal 1) and Surgery portal (Portal 2). Door 1 (1 cm in diameter) is located inside the metal tube, formed by a sleeve between the 8th and 9th ribs. Door 2 (2-3 cm in diameter) is formed by a scalpel and high-frequency electrocautery, located between the 5th and 6th ribs. Insert the 10/11 mm trocar cannula through the chest wall into the portal vein 1. Connect the endoscope (0°, diameter 10 mm, length 330 mm, Olympus) to the video endoscope camera and light source (Olympus) Linbas) and enter the chest cavity through the cannula. Use an electrocoagulation hemostatic knife to stop the end of the hemostatic door 2. Lung grasping forceps are used to lift the lung lobes to expose the lung hilum. Use hemostats and homemade tools to carefully separate the pulmonary artery, pulmonary vein and bronchi. Electrocautery is used to separate excess tissue. Clamp the pulmonary artery and vein and make it transect, then the bronchus is transected and then ligated. Bronchial ligation requires additional penetrating sutures. All lung lobes were removed from the left chest in the following order: middle lobe, upper lobe, and adjacent lower lobe. Use a syringe to check the bronchial ligation with normal saline (about 200 ml, about 40°C) in the chest cavity, and use a vacuum cleaner to suck the liquid.

  Chest surgery: Use a scalpel and an electrocoagulation knife to make an 8-10 cm incision between the 7th and 8th ribs. Cut off the 8th rib to improve working space and vision. Use a high-frequency electrosurgical knife for coagulation. Use a wound dilator to enlarge the surgical area. The operation steps are the same as those of the thoracoscopy group.

  Surveillance and post-operative care: All animals are raised and monitored in the same environment. The pig’s clinical symptoms were evaluated every day for 15 consecutive days, including mental state, exercise, appetite, stool appearance and wound healing, including the presence of bleeding and inflammation. After anesthesia, the animals were placed in a warm room and transferred to a pig pen after 6 hours. There was no drinking water 6 hours after the operation, and the pigs were fed 18 hours after the operation.

  After the operation, 5 mg fentanyl patch was given every 3 days for 6 consecutive days. Antibiotic prophylaxis, intramuscular injection of cefazolin sodium (50 mg/kg) twice a day for 2 consecutive days. Record the following parameters: HR, rectal temperature, operation time, incision size, postoperative complications, standing time. Blood tests before surgery and 1, 2, 3, 5, 7 and 14 days after surgery, including white blood cell (WBC), red blood cell count (EC), lymphocyte (LY) and granulocyte (Gran) count Blood samples were collected from veins (1, 3, 5, 7 and 14 days before surgery, 4 hours before and after surgery) and centrifuged at 1000g for 15 minutes. The biomarkers in the serum stored at -80°C were analyzed, and a commercial ELISA kit was used. Specific monoclonals were given before the operation and 1, 4, 3, 5, 7 and 14 days after the operation. antibody. CRP, SAA, IL-6, and cortisol measured in the eyes. Fifteen days after the operation, the pigs were anesthetized with xylazine and ketamine hydrochloride, and then euthanized by intravenous injection of 300 mg lidocaine. An autopsy is performed to check the chest cavity and postoperative compliance. Results: All animals survived 14 days after surgery. Thoracoscopy and thoracotomy successfully completed the full thoracotomy and completely removed all 14 left lobes. The time of thoracoscopic surgery was significantly longer than thoracotomy (VATS 160.6±16.2 VS thoracotomy 123.7±13.2, P \u003c0.05). There were no perioperative or perioperative complications in the two groups of animals. There are no surgical instruments that can cause bleeding or iatrogenic trauma. The length of the skin incision in the VATS group was 4.5 to 5.5 cm, and the length of the skin incision in the thoracotomy group was 8 to 10 cm. No other abnormalities were observed in both groups. All pigs returned to normal activity levels 24 hours after the operation. Before the operation (baseline), the rectal temperature was measured during and after the operation. The rectal temperature of all animals decreased. Two pigs in the VATS group and four pigs in the thoracotomy group were 1 and 2 days after the operation. After developing a high fever, he returned to his baseline 5 days after the operation. The white blood cell counts of the two groups increased significantly at 1, 2, and 3 days after the operation (P \u003cu\→ c\→), and returned to normal after the operation. There was no significant change in the red blood cell count after the operation. Both lymphocytes and granulocytes increased significantly on the first day after surgery. The lymphocyte count returned to normal level 5 days after operation, and the granulocyte count returned to normal level 7 day after operation. The serum CRP levels of the two groups of animals increased significantly at 4 hours, 1 day and 3 days after surgery. After 7 days, it gradually decreased to baseline. On the first day after surgery, the CRP of the thoracoscopy group was significantly lower than that of the thoracotomy group. On the 1st and 3rd day after the operation, the serum SAA level of the second group increased significantly. After 7 days, it gradually decreased to baseline. The SAA of the thoracotomy group was usually higher than that of the VATS group, but the difference was not significant. There was no statistically significant difference between the two groups at any time. The serum IL-6 levels of the two groups of animals at 4 hours, 1 day and 3 days after surgery were significantly higher than the preoperative levels. After 5 days, it gradually decreased to baseline. On the first day after surgery, the level of IL-6 in the thoracoscopy group was significantly lower than that in the thoracotomy group, and there was no significant difference between the two groups. Serum cortisol levels in the two groups were significantly higher than before surgery, and gradually decreased to baseline 5 days after surgery. Four hours after surgery and the first day after surgery, cortisol was significantly higher than the preoperative level. At 4 hours and the first day after surgery, the cortisol level of the VATS group was significantly lower than that of the thoracotomy group. At other time points, there were no significant differences in cortisol levels between the two groups.

  Conclusion: The use of minimally invasive surgical techniques (VATS) can reduce acute phase reactions, surgical pressure and postoperative pain in pigs. Thoracoscopic surgery is the ideal choice for swine breast surgery.