The Hemostatic Effect Of Non-pneumatic Intra-abdominal Compression On Liver Injury In Rats And It's Related Studies

BACKGROUND: With the advanced development of laparoscopic techniques, the studies about the various changes induced by pneumoperitoneum have been invesgated. Surgeons find that intra-abdominal insufflation has a role of hemostatic effect in their practice.It was reported that the pneumoperitoneum itself had the hemostastic effect on inferior vena cava injury and bleeding below the spleen capasule,However further study addresses the effectiveness on solid organ injuries, such as liver, has not been reported. On the other hand, liver trauma accompanying other multiple organs is frenquently occurred in wars.Emergent therapeutic measures should be adopted with in the golden hours so as to reduce the mortality and morbidity. So it is extremely important to develop a novel, but simple effective hemostatic method or device which is suitable for urgent employment.Given that CO₂ pneumoperitoneum has the potential adverse effects of hypercapnia and gas embolism as well as wounds of abdominal cavity in wars are open abdominal wounds, so the non-pneumatic intra-abdomial compression is attempted to build, which could cause intra-abdominal hypertension equally in a similar way like pneumoperitoneum, So the feasibility and its hemostatic mechanism as a prehospital method or as an adjuvant device to damage control surgery should be evaluated and discussed.PURPOSE: In the experimental part: To observe the hemostatic role of the various non-pneumatic intra-abdomial compression on liver injury and its related studies, including : 1, the hemostatic effects of intra-abdominal compression on liver injury in rats;2, the hemodynamic changes of the multiple organs under different magnitude of intra-abdominal pressures;3, the systemic hemodynamic and metabolic changes, including blood gas which may refect the status of tissue oxidation, such as levels of serum lactate and so on. In the clinical part: To observe the hemodynamic changes of the femoral vein in patients undergoing CO₂ pneumoperitoneum. METHODS: 1,The liver injury model was established in rats and then the differentIAPs (0,5,10,15mmHg) were induced through an inflatable gasbag, which could be insufflated by air. Ringer's solution was infused to maintaining a mean arterial pressure (MAP) of lOOmmHg.At the end of 30min,MAP,HR,the death rate, the volume of infusion liquid and total blood losses were also recorded;2,Various IAPs were built in different rats repectively or in one rat repeatedly. The parameters, such as ICG-clearance,non-radiated colored microspheres method, were applied to assess the blood flow of liver and others organs. Ink-perfusion was also used to delineate the morphologic changes of the viscera microvessels;3, The impact of the different IAPs on systemic hamodynamics and other parameters,such as the blood gas, serum lactate and liver and renal function were also measured in different intervals;4,The flows of femoral vein on 28 LC patients (ASA I - II )undergoing CO2 pneumoperitoneum were measured directly by the investigator with duplex ultrasonograph. RESULTS:1,The total blood loss of group IAPIO was significantly less than that of groupIAPO and the blood loss was least in group LAP 15, however, animals could not withsdand the intra-abdominal pressure of 15mmHg, A high mortality of 80% was only found in group IAP15;2, The blood flow of organs, such as liver and kidney was decreased significantly with the increased increments of intra-abdominal pressure, which was correlated with reduced cardiac output, however, the blood flows of vital organs, such as heart and brain, could be maintained when IAP between 5-10mmHg, the blood perfusion of those organs were also reduced with further elevated IAPs. The morphologic changes of Ink perfusion on microvasculars was depended on the organs blood flow, the microvessles was showed clearly as blood flow increased, on the other hand, Ink perfusion to the microvessles was reduced or no stained if the blood flow reduced. 3,Various IAPs had no effects on HR,but MAP decreased significantly as the IAP increased to 15mmHg and returned to normal level after desulfflation;The changes of blood gas and lactate was also apparent in group IAP 15 and the metabolic acidosis was existed in this group due to the increased level of lactate. 4,CC>2 pneumoperitoneum(14mmHg) could lead to the reduced blood flow and reverse flow occasionally was found in the femoral vein in patients performing for LC. The reverse Trendenburg position had an additive role on venous flow stasis.CONCLUSIONS: l,The use of an inflatable gasbag for the intra-abdominal compression test the effectiveness of non-pneumatic hemostastic role in liver injury for early resuscitation. 2,The reduction of blood perfusion in abdominal viscera, which is caused by elevated intra-abdominal pressure, is one of the hemostatic mechanisms. In addition, the elevated intra-abdominal pressure has the potential role on blood redistribution, blood perfusion to heart and brain were maintained relatively well;3,The safty level and duration of intra-abdomianl hypertention was investigated, for higher or longer IAP could lead to systematic hemodynamic changes and metabolic acidosis. For rats, the safety levels of IAP should be less than 15mmHg. 4, In human beings, 14mmHg of intra-abdominal pressure will lead to the reduce of the femoral venous flow, the head-up position has the additive role on the venous stasis. In conclusion, non-pneumatic intra-abdominal compression, which is used in a certain degree, can be adopted as one of prehospital hemostatic method of injury control at an early stage of liver injury and the adverse effects of IAH, such as abdominal compartment syndrome, should be avoided. Nevertheless, further works is required to define the usefulness,safety and feasibility of using non-pneumatic intra-abdominal compression as one of prehospital treatment to the field wound resuscitation in wars, including the optimum intra-abdominal pressure, the delayed effects of abdominal viscera after a long-term compression and the relationship between the various degree of intra-abdominal compression and the impacted organs function under the corresponding IAH.