动物实验,腹膜内压力（IAP） z-bo 2020-09-02 434

　　Background: Intraperitoneal pressure (IAP) higher than 12 mmHg is considered a pathological increase, called intra-abdominal hypertension (IAH). Pancreatitis, trauma, capillary leakage, transient tamponade and increased intra-abdominal pressure caused by visceral edema can lead to abdominal syndrome (ACS). Early studies have shown that IAH can increase renal vein pressure, increase renal parenchymal pressure, reduce renal blood flow and glomerular filtration rate, and cause oliguria or anuria. Renal ischemia and renal parenchymal compression can activate the renin-angiotensin steroid system, which in turn causes retention of body fluids and sodium. This effect further increases vascular resistance and may lead to a vicious circle. Previous studies have shown that increased intra-abdominal pressure can lead to obstructive and non-obstructive renal pelvic excretion disorders. The treatment of IAH includes surgical and non-surgical methods, but the optimal surgical plan has not been determined. Airtight negative pressure seal drainage (VSD) is currently the most commonly used temporary abdominal sealing strategy. Intraperitoneal dilatation (IAVI) is a modified IAH technique; other tests are needed for the impact of abdominal surgery on renal function, including imaging studies that compare tissue changes before and after surgery. In this study, the portal vein was not completely blocked and IAH was induced to improve the effect of IAH on the kidney after hemorrhagic shock and resuscitation, and established the clinical success rate of IAV, and established a large animal IAH model. The therapeutic effect was studied.

　　Method: Animals: 12 healthy small groups with an average weight of 22.9±1.7 kg. set up

　　IAH model of hemorrhagic shock and resuscitation: animals were fasted for 12 hours before surgery, water was released before surgery, and animals were anesthetized with ketamine (7.2 mg/h/kg) and 3% pentobarbital sodium (6 mg). Place the experimental animal on the bench and disinfect the skin. Insert the trachea and maintain anesthesia through a breathing anesthesia machine connected to pure oxygen. Separate the right femoral artery and vein, and insert a single lumen catheter. The multifunctional sensor and the monitor are connected through the tea water pipe. The right femoral artery cannula causes bleeding, and the venous cannula is used for inferior vena cava injection and pressure sensing. After opening the abdomen, proceed to bladder fistula. Separate the portal vein and ligate the blood vessel with a strong plastic tube (outer diameter 5 mm) and silk thread. Remove the rigid plastic tube and create a model of complete portal vein occlusion to simulate the perihepatic accumulation process in severe liver injury. The aorta bleeds until the mean arterial pressure (MAP) reaches 50 mmHg, and the blood is stored in the blood bag. The abdominal incision was closed with layered sutures. One hour after shock, all the blood lost is returned to the body with Ringer's solution (twice the blood). Give Ringer's solution continuously until recovery. If IAP≥12 mmHg IAP is maintained for 1 hour, it is considered that the IAH model has been successfully established. The model was successfully established, but four people died of hemorrhagic shock. Animal grouping and stage observation: 4 dead animals were excluded from the study. By throwing coins, the remaining eight were divided into IAVI group (n = 4) and sham operation group (n = 4). The procedure of IAVI treatment is as follows: remove the abdominal incision and sutures, extend the incision from the xiphoid process to the pubic symphysis, loosen and remove the portal vein ligation, and remove the upper intestinal net. Place the polyvinyl alcohol gelatin sponge on a net about 30 x 20 cm and suture it to the abdominal wall. Pull out the drainage tube from one side of the incision and insert it into the sponge. Use a biopermeable membrane with good air permeability and good air permeability to cover the incision and sponge until the incision is closed. By using the flow tube to continuously suck the animal until the animal is killed, a negative pressure of 60 mm Hg to 80 mm Hg can be maintained. In the sham operation group, an abdominal incision was made and sutured, which extended from the xiphoid process to the symphysis pubis. Loosen and remove the door ligature and layered sutures, and directly close the incision. Before impact, measurements were started 2 hours after IAH and 22 hours after surgery. The animals were sacrificed by intravenous injection of 0.2 g of ketamine and 10 ml of 10% potassium chloride.

　　Renal function index measurement: Obtain hourly urine volume (UV) readings. Before shock, 2 hours after IAH and 22 hours after surgery, blood samples obtained from the inferior vena cava catheter were used to measure creatinine and urea nitrogen levels.

　　Measure the indicators affecting kidney function: before shock, 2 hours after IAH, 22 hours and 26 hours after surgery, measure the following indicators: (1) Bladder perfusion pressure (IVP): Empty the bladder and inject 50 ml into the bladder and silicone tube brine. upright. When it drops to a stable level, the vertical height of the water column above the pubic symphysis is the bladder perfusion pressure. (2) Inferior vena cava pressure (CVP): Use a multifunctional monitor to measure the inferior vena cava pressure through an inferior vena cava catheter. (3) Color Doppler: Based on the data obtained from the right kidney, measure the thickness of the renal cortex to observe whether the renal pelvis and the cup are separated. (4) Enlarged CT scan: measure the ratio of the front and back diameter of the abdomen (at the level of the left renal vein, subcutaneous fat is removed). Based on the data obtained from the right kidney, the thickness of the widest part of the kidney and the length of the renal pelvis are measured. (5) Dry/wet ratio of kidney tissue: Collect the upper 1/8 of the left kidney tissue, collect and weigh the kidney sample, and then place it in a dry box at 60°C for 3 days. A wet/dry ratio of 4 to 4.5 and above indicates severe organ edema. 6) Kidney histopathology: Take the upper 1/8 of the right kidney, fix it with 10% formalin, embed it in paraffin, section, HE stain and observe with an optical microscope.

　　Result: IAH model: the average weight is 22.90±1.70 kg, and the MAP baseline value is 118±14.30 mmHg. Bleeding until MAP reached 50 mmHg; bleeding volume was 648±98 ml. The baseline of IVP was 6.65±0.50 mmHg. When IVP is 3.20±0.60h, 21.16±? If it reaches 4.63 mmHg, the required amount of ranger fluid is 76±3 ml/kg/hour. Two pigs developed rectal prolapse and stress urinary incontinence.

　　8 out of 12 pigs established an IAH model (66%). In the IAVI group, 4 pigs survived the observation period. In the sham operation group, 2 out of 4 pigs died of respiratory failure 18 and 20 hours after the onset of IAH. The ultraviolet radiation 2 hours after the onset of IAH was significantly lower than before the electric shock (55±11 ml/h vs. 156±35 ml/h, P\u003c0.01). In the IAVI group, urine output returned to normal (120±23 ml/h and 55±11 ml/h, p\u003c0.01), but did not reach normal levels. The urine output of the sham operation group was significantly lower than that of the IAVI group. Two hours after the beginning of IAH, the levels of Cr and UR in the blood increased, but there was no significant difference. After IAVI treatment, CR and UR continued to increase slowly. The CR and Ur of the sham operation group were significantly higher than those of other groups. The dry weight ratio of kidney tissue in sham operation group was significantly higher than that in IAVI group.

　　Related factors affecting renal function: 2 hours after IAH, intravenous pyelography and inferior vena cava pressure were significantly higher than before shock. 22 After IAVI treatment, IVP and inferior vena cava pressures were significantly reduced, and both were slightly higher than before shock, but there was no significant difference. The inferior vena cava pressure and IVP in the sham operation group were significantly higher than those in the IAVI group.

　　Image change: When calculating the ratio of the front and back diameter to the horizontal diameter, the ratio 2 hours after the start of IAH was significantly higher than the baseline value. The CT examination of the kidney height of the right kidney showed no significant difference between the IAVI group and the sham operation group. The thickness of the right renal cortex was measured by B-ultrasound, and there was no significant difference between the IAVI treatment group and the sham operation group. The diameter of the right renal sinus was measured by CT. There are no major changes in IAH. All animals had no hydronephrosis or separation of renal pelvis and urinary tract in any aspect. Pathological results: obvious hyperemia and inflammatory cell infiltration in the kidney tissue of the sham operation group. The IAVI group had mild or no hyperemia and mild inflammatory cell infiltration.

　　Conclusion: Abdominal cavity syndrome usually occurs in critically ill patients and may affect various organ systems. The kidney is the most common organ. Observe the correlation between the reduction of IAP caused by IAVI and the improvement of renal function. IAVI can help control renal insufficiency after IAH and reduce intra-abdominal pressure, thereby reducing renal edema and congestion.