The Effect Of Intra-abdominal Volume Increment On Lungs And Heart For The Treatment Of Intra-abdominal Hypertension Occurring After Hemorrhagic Shock Resuscitation In Minipigs

According to the current guidelines of the World Society of the AbdominalCompartment Syndrome (WSACS), intra-abdominal hypertension (IAH) is defined as IAP≥12mmHg. Generally speaking, change of abdominal volume could lead to an increase inIAP. In the treatment of hemorrhagic shock, a large amount of resuscitation fluid is used tostabilize the effective circulation. The shock often results in capillary leakage, with muchliquid penetrating the third space and also lead to the occurrence of intestinal edema andascites, thus revoking an increase in IAP and even leading to IAH and ACS.The effect of increased IAP on lungs had been recognized for many years. IAP istransmitted to the chest directly or indirectly through the diaphragm, which can cause adecrease in total lung volume and the oxygenation，increase intrathoracic pressure, decreasereturned blood volume, increase the compression to the heart resulting in the decrease of EFand increase of HR.Abdominal decompression or volume increment is an important method for thetreatment of IAH or ACS, few reports are focused on their effects on lung function,particularly in large animals with similar physiological functions as humans.We established an IAH model of minipigs, which simulated the situation of perihepaticpacking after clinical hemorrhagic shock resulting from serious hepatic injury, fluidresuscitation and IAH. Then IAVI assisted by a vacuum sealing drainage was used to treatthe IAH and its effect on lung and heart function was our research focus.Twelve healthy adult minipigs underwent femoral artery cannulation and bloodlettingto establish a model of hemorrhagic shock (the mean arterial pressure was50mmHg,1h).The portal vein of the minipigs was incompletely blocked, and the established8IAHmodels were then randomly divided into two groups: the IAVI treatment group (n=4) and the sham-operated control group (n=4). Arterial blood was extracted for blood gas analysisbefore shock,1h after shock,2h after IAH,8h after surgery and12h after surgery.Diaphragm height and value of pulmonary computed tomography were measured beforeshock,2h after IAH and22h after surgery, HR and MAP was observed before shock,1hafter shock,2h after IAH,8h after surgery and12h after surgery. FS and EF weremeasured before shock,2h after IAH and22h after surgery. Twenty-six hours after surgery,the minipigs were sacrificed, and lung and heart samples were collected to measure thewet-to-dry weight ratio and to perform hematoxylin-eosin staining.Due to incomplete occlusion of the portal vein during hemorrhagic shock recovery,resuscitation can result in IAH, which is accompanied by pulmonary dysfunction becauseof diaphragm elevation and pulmonary interstitial edema, which is accompanied by heartdysfunction，decreased returned blood volume, decreased preload, compressed heart andaorta, increased afterload, increase the compensation of heart rate. Shortly after IAVIsurgery, by reducing intra-abdominal pressure (IAP) to lower the diaphragm, we observedsome improvements in the pathological conditions such as interstitial pulmonary edema.Intra-abdominal volume increment can decrease intrathoracic pressure, increase returnedblood volume, reduce the compression to the heart, and increase the complaisance of heart,resulting in the notable improvement of HR and EF.