[Animal Experiment]-Evaluation of the application of a new piezoelectric driven pulsed water jet system in pig model liver resection

动物实验

z-bo

2020-09-04

380

Background: In order to reduce intraoperative blood loss during liver surgery, many interventions have been introduced because excessive blood loss increases the risk of postoperative complications. Vascular occlusion techniques and low central venous pressure anesthesia are widely used to reduce bleeding during parenchymal resection. The introduction of hemostatic equipment, such as argon knife, ultrasonic coagulation scissors, saline and radiofrequency technology, and vascular stapler, helps reduce blood loss during liver resection. The finger fracture technique was developed in the 1960s to dissect liver parenchyma while preserving liver blood vessels. This is followed by the introduction of the forceps method of ultrasonic aspirator (UA), and the dissector with continuous water jet. However, while preserving hepatic blood vessels, reducing blood loss and reducing operation time, the best method for liver parenchymal resection remains to be determined. At present, the substantive anatomy method used in surgery depends to a large extent on the surgeon's choice. The continuous water jet dissector allows the surgeon to dissect organs while preserving the diameter of blood vessels exceeding 100-200 μm. However, these tools have some limitations, especially the formation of bubbles, which obscures the surgical field, and splashes of blood can increase the risk of cross-infection between surgeons and nurses. Pulsed water jet stripping technology is a new technology that can significantly reduce the consumption of tissue stripping. Therefore, this technique can reduce bubble formation and splashing. In a recent neurosurgery study using a laser-induced pulsed water jet device, researchers significantly reduced intraoperative blood loss and the number of operations, while increasing the tumor volume in patients with complex pituitary tumors and skull base lesions. The piezoelectric actuator drive (ADPJ) of the pulsed water jet system is a new technology that emits a small amount of stable pulsed water, allowing fine control of the anatomy of the soft tissue prosthesis. Using pig liver in vitro, this system allows the operator to dissect the liver parenchyma while preserving the hepatic vein and Glisson sheath. The peak pressure of the pulsed water jet is controlled by changing the input voltage. The purpose of this study was to evaluate the feasibility, effectiveness and safety of the adpj hepatectomy method in a pig model and compare it with a widely used device (ie UA).

　　Method: ADPJ Overview: ADPJ consists of a machine head, a supply pump, and a controller. The piezoelectric actuator has a displacement of 20 μm and has no effective load when the input voltage is 150 V. It is glued to an aluminum disk as a piston. The piston is glued to a stainless steel diaphragm (0.02 mm thick) and fixed to the edge of the metal wall, but at its center, it is separated from the metal wall by 0.1 mm in order to inject water into the room. A stainless steel connecting pipe with a diameter of 1.1 mm is directly connected to the actuator. A nozzle (0.15 mm diameter) is connected to the connecting pipe. A supply pump continuously injects physiological saline into the room at a controllable flow rate through a capillary inlet (0.3 mm in diameter). To drive the piston, pressure is applied to the piezoelectric actuator at a specific frequency. Therefore, pulsed water jets are injected at a pulse rate based on frequency.

　　 Animals: Ten pigs (2 males, 8 females), with an average weight of 36 kg.

　　 ADPJ settings: pulsed water jet frequency is 400 Hz, driving voltage is 80 V, flow rate is 7 ml/min normal saline. Various parameters were measured in preliminary experiments, and different driving voltages and flow rates were tested during the dissection of pig liver.

　　 Anesthesia: Animals use 0.04–0.06 mg/kg dexmedetomidine, 0.2–0.4 mg/kg midazolam, and 0.2 mg buprenorphine hydrochloride. During surgery, isoflurane gas is used to maintain anesthesia. The heart rate, blood oxygen saturation, two-lead electrocardiogram and arterial blood pressure were continuously monitored throughout the process. The central venous pressure was measured at the beginning and end of liver resection, which was approximately 5 mm Hg. Postoperative analgesia uses rectal buprenorphine and acetaminophen.

　　 Surgical operations: The same surgeon performed all liver resections. The liver was examined by a midline laparotomy. After cholecystectomy, remove the right lower edge of the right middle lobe. This section of Glissonean pedicle is surrounded and ligated to the hepatic hilum, without liver dissection. Confirm the liver parenchyma at the junction of the ischemic area and the residual area after the operation. All resections were performed with temporary vascular occlusion. When the arterial systolic pressure drops to 80 mmHg or the blood oxygen saturation drops below 90%, stop vascular occlusion and hepatectomy. After the arterial systolic pressure and blood oxygen saturation were restored, vascular occlusion and hepatectomy were performed again.

　　Experimental design: 10 animals were randomly divided into two groups. Each animal dissected the liver sac with a scalpel. Use ADPJ (group A, n=5) or ultrasonic aspirator (group U, n=5) for parenchymal transection and vascular skeletalization. Electric knife cuts and cauterizes small blood vessels (usually less than 1 mm in diameter), before cutting Ligation of large blood vessels. The blood loss is calculated by adding the volume of the inhaled gauze swab to the container of the suction device. The amount of blood lost by ADPJ or UA is subtracted from this volume by the volume of saline injected with adpj or UA. The duration of the hepatic parenchymal resection is measured from the beginning to the end, excluding the waiting time of the Pringle method. Therefore, the transection time corresponds to the hepatic portal block time. On the 7th day after the operation, the abdominal cavity was checked for short-term intra-abdominal complications, and then the animals were sacrificed with excessive potassium chloride.

　　 Determination of serum electrolytes: Blood samples were collected from each animal before surgery and after hepatectomy. Serum was prepared by centrifugation at 1750×G for 15 minutes at 4°C, and then filtered. After filtration, the serum electrolyte concentration (sodium and chloride) is determined.

　　 Histopathological evaluation: After liver resection, it was fixed with formaldehyde and embedded in paraffin. Hematoxylin-eosin staining sections were used to evaluate the histopathological characteristics of excised tissue specimens.

　　Result: Surgical result: Resection of liver parenchyma, the use of ADPJ has little blood vessel loss, and there is no significant difference in central venous pressure between group A and group U. Both groups of animals tolerated the operation, and there were no complications such as hemorrhage during the operation. However, one pig in group U died a few hours after the operation. The pig tolerated the surgery. The blood loss of this pig was 362.4 ml, which was not much loss compared with the average blood loss of the other 9 pigs. However, at the end of the operation, the pig’s blood oxygen saturation and arterial blood pressure dropped. After waking up from anesthesia, blood pressure and blood oxygen saturation recovered. Transfer to the rescue room after successful extubation. The pig died in the recovery room a few hours after the operation. There was no postoperative bleeding or bile leakage. The remaining four pigs in group U and all pigs in group A survived for 7 days without postoperative bleeding or bile leakage.

　　 Serum sodium and chloride ion concentration: All animals had a slight decrease in serum sodium and chloride ion concentration after hepatectomy, except for group A. The serum sodium concentration after hepatic parenchyma transection in group A was significantly higher than that in group U. There was no significant difference in serum sodium concentration and serum chloride ion concentration before and after surgery between group A and U.

　　 Histopathological findings: Histological analysis showed that ADPJ was used to transcribe the liver parenchyma while retaining the Glisson sheath, including the portal vein, artery and bile duct. The cross-section of liver tissue with UA is more blunt than with ADPJ, and more liver cells are lost.

　　 Conclusion: We successfully performed hepatectomy using ADPJ on the pig model. The results of the study show that, like UA, ADPJ is a safe and feasible tool for liver parenchymal resection. The various settings of adpj have great potential, and future research should explore the use of this system in translucent endoscopic hepatectomy and robotic surgery.