Two clinically relevant pressures of carbon dioxide pneumoperitoneum cause hepatic injury in a rabbit model.

AIM: To observe the hepatic injury induced by carbon dioxide pneumoperitoneum (CDP) in rabbits, compare the effects of low- and high-pressure pneumoperitoneum, and to determine the degree of hepatic injury induced by these two clinically relevant CDP pressures. METHODS: Thirty healthy male New Zealand rabbits weighing 3.0 to 3.5 kg were randomly divided into three groups (n = 10 for each group) and subjected to the following to CDP pressures: no gas control, 10 mmHg, or 15 mmHg. Histological changes in liver tissues were observed with hematoxylin and eosin staining and transmission electron microscopy. Liver function was evaluated using an automatic biochemical analyzer. Adenine nucleotide translocator (ANT) activity in liver tissue was detected with the atractyloside-inhibitor stop technique. Bax and Bcl-2 expression levels were detected by western blotting. RESULTS: Liver functions in the 10 mmHg and 15 mmHg experimental groups were significantly disturbed compared with the control group. After CDP, the levels of alanine transaminase and aspartate transaminase were 77.3 ± 14.5 IU/L and 60.1 ± 11.4 IU/L, respectively, in the 10 mmHg experimental group and 165.1 ± 19.4 IU/L and 103.8 ± 12.3 IU/L, respectively, in the 15 mmHg experimental group, which were all higher than those of the control group (P < 0.05). There was no difference in pre-albumin concentration between the 10 mmHg experimental group and the control group, but the pre-albumin level of the 15 mmHg experimental group was significantly lower than that of the control group (P < 0.05). No significant differences were observed in the levels of total bilirubin or albumin among the three groups. After 30 and 60 min of CDP, pH was reduced (P < 0.05) and PaCO2 was elevated (P < 0.05) in the 10 mmHg group compared with controls, and these changes were more pronounced in the 15 mmHg group. Hematoxylin and eosin staining showed no significant change in liver morphology, except for mild hyperemia in the two experimental groups. Transmission electron microscopy showed mild mitochondrial swelling in hepatocytes of the 10 mmHg group, and this was more pronounced in the 15 mmHg group. No significant difference in ANT levels was found between the control and 10 mmHg groups. However, ANT concentration was significantly lower in the 15 mmHg group compared with the control group. The expression of hepatic Bax was significantly increased in the two experimental groups compared with the controls, but there were no differences in Bcl-2 levels among the three groups. Twelve hours after CDP induction, the expression of hepatic Bax was more significant in the 15 mmHg group than in the 10 mmHg group. CONCLUSION: A CDP pressure of 15 mmHg caused more substantial hepatic injury, such as increased levels of acidosis, mitochondrial damage, and apoptosis; therefore, 10 mmHg CDP is preferable for laparoscopic operations.

[Effects of different intraabdominal pressure of carbon dioxide pneumoperitoneum on hemorrheology and microcirculation in rabbits].

OBJECTIVE: To study effects of different intraabdominal pressure of carbon dioxide (Cq2) pneumoperitoneum on hemorrheology and microcirculation in rabbits. METHODS: Eighteen female healthy rabbits weighing 2.2 kg to 3.5 kg were randomly divided into three groups equally based on pneumoperitoneum pressure: 0 mmHg group (group I),10 mmHg group (group II) and 15 mmHg (group III). Each group received 1 h pneumoperitoneum under different pressure. Blood samples were taken at 5 min before CO2 pneumoperitoneum, at 30 and 60 min after pneumoperitoneum for the measurements of indexes of hemorrheology. Hemodynamics including heart rate (HR), mean arterial pressure (MAP) and the volume and velocity of the microcirculation of auricle were continuously monitored, such indexes were recorded at the related time. RESULTS: Afer pneumoperitoneum at 30 and 60 min, compared with group I, HR, MAP, the whole blood viscosity, the aggregation and rigid indexes of RBC were significantly raised in group II (P < 0.05), the deformability indexes of RBC, the volume and velocity of the microcirculation were markedly decreased (P < 0.05). Even more significant changes were observed in group III (P < 0.01). The plasma viscosity and the hematocrit changed little. CONCLUSION: After CO2 pneumoperitoneum, hemorrheology is decreased; Although HR, MAP are raised, the volume and velocity of the microcirculation are decreased.

Hepatic injury induced by carbon dioxide pneumoperitoneum in experimental rats.

AIM: To observe the hepatic injury induced by carbon dioxide pneumoperitoneum in rats and to explore its potential mechanism. METHODS: Thirty healthy male SD rats were randomly divided into control group (n = 10), 0 h experimental group (n = 10) and 1 h experimental group (n = 10) after sham operation with carbon dioxide pneumoperitoneum. Histological changes in liver tissue were observed with hematoxylin-eosin staining. Liver function was assayed with an automatic biochemical analyzer. Concentration of malonyldialdehyde (MDA) and activity of superoxide dismutase (SOD) were assayed by colorimetry. Activity of adenine nucleotide translocator in liver tissue was detected with the atractyloside-inhibitor stop technique. Expression of hypoxia inducible factor-1 (HIF-1) mRNA in liver tissue was detected with in situ hybridization. RESULTS: Carbon dioxide pneumoperitoneum for 60 min could induce liver injury in rats. Alanine aminotransferase and aspartate aminotransferase were 95.7 +/- 7.8 U/L and 86.8 +/- 6.9 U/L in 0 h experimental group, and 101.4 +/- 9.3 U/L and 106.6 +/- 8.7 U/L in 1 h experimental group. However, no significant difference was found in total billirubin, albumin, and pre-albumin in the three groups. In 0 h experimental group, the concentration of MDA was 9.83 +/- 2.53 micromol/g in liver homogenate and 7.64 +/- 2.19 micromol/g in serum respectively, the activity of SOD was 67.58 +/- 9.75 nu/mg in liver and 64.47 +/- 10.23 nu/mg in serum respectively. In 1 h experimental group, the concentration of MDA was 16.57 +/- 3.45 micromol/g in liver tissue and 12.49 +/- 4.21 micromol/g in serum respectively, the activity of SOD was 54.29 +/- 7.96 nu/mg in liver tissue and 56.31 +/- 9.85 nu/mg in serum, respectively. The activity of ANT in liver tissue was 9.52 +/- 1.56 in control group, 6.37 +/- 1.33 in 0 h experimental group and 7.28 +/- 1.45 (10(-9) mol/min per gram protein) in 1 h experimental group, respectively. The expression of HIF-1 mRNA in liver tissue was not detected in control group, and its optical density difference value was 6.14 +/- 1.03 in 0 h experimental group and 9.51 +/- 1.74 in 1 h experimental group, respectively. CONCLUSION: Carbon dioxide pneumoperitoneum during the sham operation can induce hepatic injury in rats. The probable mechanisms of liver injury include anoxia, ischemia reperfusion and oxidative stress. Liver injury should be avoided during clinical laparoscopic operation with carbon dioxide pneumoperitoneum.

[Changes of rabbit IL-1 and TNF-alpha, etc cytokines in response to acute normovolemic hemodilution with HAES-balanced solution as diluting agent].

AIM: To observe effect of acute normovolemic hemodilution(ANH) with HAES-balanced solution as diluting agent on levels of cytokines including IL-1, IL-2, IL-6 and TNF-alpha in rabbit serum so as to provide theoretical basis for clinical application. METHODS: A total of 20 healthy adult rabbits were enrolled in the study and randomly divided into two groups (10 rabbits per group), i.e., control group (Group C) and HAES group (Group H). Under anesthesia of the rabbits, we performed incision of trachea, high-frequency jet ventilation and liberation of femoral artery and femoral veins. Group C was free from hemodilution. Group H was injected with dilution (2-fold of blood letting volume) via femoral veins during blood letting of the femoral artery. 6% HAES-steril plus compound solution of sodium lactate, with crystal/gel ratio of 2:1, blood letting volume = TBV x (Ho-Hf)/Hav. All blood was transfused back 60-120 min after blood letting. Venous blood was collected before blood letting (T0) and 30 min (T1), 60 min (T2), 120 min (T3) and 24 h(T4) after blood letting to detect Hb and Hct and measure level of IL-1, IL-2, IL-6 and TNF-alpha in serum. RESULTS: In Group H, levels of IL-1, IL-2, IL-6 and TNF-alpha in serum were increased from T1 after ANH, reached peak at T3 but showed decrease at T4, with significant difference compared with Group C at T1, T2, T3 and T4 (P < 0.01) and significant difference compared with those before ANH (P <0.01). In Group C, there was no significant difference upon IL-1, IL-2, IL-6 and TNF-alpha in serum at different time points. CONCLUSION: ANH with HAES-balanced solution as diluting agent can up-regulate the levels of cytokines IL-1, IL-2, IL-6 and TNF-alpha in rabbit serum. In the meantime, ANH may arouse eustress with low intensity and short action time, which exerts effect of enhancing immune function of the organisms.