Effects Of CO₂ Pneumoperitoneum On The Hemodynamics In Atherosclerosis Rabbits

Objective To investigate the effects of CO2 pneumoperitoneum on hemodynamics of atherosclerosis rabbits.Methods Fifty Japan white rabbits were randomizedly divided into two experimental and two control groups.Rabbits were subjected to CO2 pneumoperitoneum with an intraabdominal pressure of 10 and 15 mmHg for 2 hour as designed for experimental groups. Rabbit model of atherosclerosis was created.We assessed the changes in hemodynamic parameters caused by CO2 pneumoperitoneum.The neck of the rabbits were exposed. Invasive monitoring methods were used to monitor hemodynamic changes of the rabbits using polygraph system after left carotid artery and right external jugular vein were cannulated successsfully.CO2 pneumoperitoneum of different pressures were established by closed method.Artery blood samples were collected for measuring plasma concentrations of angiotension I ,angiotension II and aldosterone by radioimmunoassay Which were repeated before the onset of CO2 pneumoperitoneum,at 30 minute intervals during pneumoperitoneum, 30 minute after deflation.All of the animals were killed 1 day after abdonmal deflation, The hearts and arteries were removed and fixed in a 10% buffered formalin solution.and then observed by conventional light microscropy.Results (l)After establishment of pneumoperitoneum, the level of LVEDP was increased in comparison with that of preinsufflation.However,there were significant decrease in CVP +DP/DTand -DP/DT,which did not return to normal level even 30 min after deflation in group 1 and 3. There were statistically significant differences both within and between groups in +DP/DT ,-DP/DT,LVEDP and CVP. (2)The changes in +DP/DT were correlated negatively to those in angiotension II (r=0.87,P<0.05). In the pneumoperitoneum groups,there was a significant increase inHR at 30 min after insufflation and a significant decrease at 30 min after exsufflation. The LVESP,however, had no significant differences in any of the of the groups. (3)Histological view of the arteries showed atherosclerosis models of rabbits had been established.Cellular swelling occurred in myocardium cells 1 day after abdominal deflation in the 10 and 15 mmHg pneumoperitoneum groups.Conclusions Under atherosclerosis conditions, CO2 pneumoperitoneum has an short-term adverse influence on the hemodynamics of the rabbits.The mechanism behind the hemodynamic changes induced by CO2 pneumoperitoneum may be multifactorial. Longer-duration, increased intraabdominal pressure and activated renin-angiotension- aldosterone system may contribute to the changes.