ObjectiveTo study the concepts and pathophysiology of intraabdominal hypertension (IAH) and abdominal compartment syndrome (ACS). MethodsRelevant information was gathered from previous original articals,and by checking the latest issues of appropriate journals. Meantime computerised MEDLINE search from 1998 to August 2001 was conducted using the Medical Subject Heading and textwords “abdominal”, “compartment syndromes”, “intraabdominal” and “hypertention” and “pressure”.Then the literature in the recent two years about the advances of IAH and ACS were reviewed. Especially the concepts, pathophysiology and clinical application of IAH and ACS were mainly summarized.ResultsAkin to compartment syndrome, the pathophysiological effects of increased intraabdominal pressure developed well before any clinical evidence of compartment syndrome. These changes included ①reduction of gastrointestinal blood flow，②increase of respiratory airway pressure whereas decrease of pulmonary compliance，③decline in cardiac output but rise in peripheral vascular pressure，④oliguria even anuria，⑤increase of intracranial pressure，⑥decrease of hepatic blood flow，⑦decrease of abdominal wall compliance.ACS can be defined as dysfunction of various organs caused by a progressive unphysiologic increase of the intraabdominal pressure. Clinically the syndrome is characterised by inadequate ventilation, tensely distended abdomen and oliguria or anuria.Early decompression by simple laparotomy and delayed closure is the treatment of choice. ConclusionThe concepts of IAH and ACS have been increasingly accepted. They mainly affects the respiratory,cardiovascular and renal systems; secondarily affect gastrointestinal, central nervous systems,liver and abdominal wall. The reduction of cardiac output and pulmonary compliance are probably promoting factors inducing organ dysfunction.
Objective To investigate the effect of intra-abdominal hypertension(IAH) on respiratory function in pigs.Methods Twelve pigs were randomly divided into two groups (n=6 in each group),ie.IAH20 group(intra-abdominal pressure=20 mm Hg) and IAH30 group(intra-abdominal pressure=30 mm Hg).Pig model of IAH was established by intraperitoneally injection of carbon dioxide.The changes in respiratory function parameters including pulmonary dynamic compliance（Cdyn），peak inspiratory pressure(PIP) ,SpO2 and PaCO2 were recorded at different time points.Results Cdyn was significantly decreased at different time points compared with baseline in group IAH30 and group IAH20.PIP significantly increased at different time points compared with baseline in both IAH groups，but group IAH30 was more severe than group IAH20. No significant changes of SpO2 and PaCO2 were found in two IAH groups.Conclusion IAH can impair respiratory function by decreasing lung compliance and increasing inspiratory pressure.
ObjectiveTo evaluate the effect of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in acute lung injury (ALI) with intra-abdominal hypertension (IAH). MethodsSix pigs were anesthetized and received mechanical ventilation (MV). Volume controlled ventilation was set with tidal volumn(VT) of 8 mL/kg,respiratory rate(RR) of 16 bpm,inspired oxygen concentration (FiO2) of 0.40,and PEEP of 5 cm H2O. ALI was induced by repeated lung lavage with diluted hydrochloric acid (pH<2.5) until PaO2/FiO2 declined to 150 mm Hg or less to established ALI model. Intra-abdominal hypertension was induced by an nitrogen inflator to reach intra-abdominal pressure of 20 mm Hg. Respiratory parameters and hemodynamics were continuously recorded at different PEEP levels(5,10,15,and 20 cm H2O). Every level was maintained for one hour. ResultsPaO2/FiO2 in PEEP5,10,15 and 20 were 90±11,102±10,172±23 and 200±34 mm Hg respectively. PaO2/FiO2 in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). Chest wall compliance (Ccw) in PEEP5,15 and 20 were 26±3,76±15 and 85±14 mL/cm H2O respectively. Ccw in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in lung compliance (CL) in different PEEP levels (P>0.05). Plateau pressure(Pplat) in PEEP5,10,15 and 20 were 30±3,31±2,36±2 and 38±4 cm H2O respectively. Pplat in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). There was no significant difference in Pplat between PEEP15 and 20 (P>0.05). Heart rate (HR) in PEEP5,15 and 20 were 113±17,147±30,and 160±30 beat/min respectively. HR in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in HR between PEEP15 and 20 (P>0.05).Cardiac index (CI) in PEEP5 and 20 were 4.5±0.6 and 3.5±0.6 L·min-1·m-2 respectively. CI in PEEP20 was significantly lower than that in PEEP5 (P<0.05). There was no significant difference in CI in PEEP5,10 or 15(P>0.05). Central venous pressure(CVP) in PEEP5,15 and 20 were 12±2,17±2,and 18±3 mm Hg respectively. CVP in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in CVP between PEEP15 and 20 (P>0.05). There were no significant differences in MAP,SVRI,ITBVI,GEDI,PVPI,or EVLWI between different PEEP levels. ConclusionConcomitant ALI and IAH can induce great impairments in respiratory physiology. When PEEP is gradually increased,oxygenation and the respiratory function are improved without significant secondary hemodynamic disturbances.