Effect of methylene blue on the hemodynamic instability resulting from liver ischemia and reperfusion in rabbits.

The experimental investigation was performed to study the effects of methylene blue (MB) on hemodynamic, biochemical, and tissue changes among rabbits undergoing liver ischemia and reperfusion (IR). Twenty-four rabbits were randomized into 5 groups: 1, SHAM, control; 2, MB infusion bolus (3 mg/kg); 3, IR, hepatic ischemia for 60 minutes followed by 120 minutes of reperfusion; 4, MB-R, undergoing ischemia that had received an MB bolus infusion (3 mg/kg) prior to reperfusion; 5, R-MB, undergoing ischemia and MB bolus infusion after hemodynamic instability caused by reperfusion. The analysis included continuous recording of vital signs. Blood samples were collected at 0, 60, and 180 minutes of IR to determine blood gases as well as biochemical markers of liver function, nitric oxide, lipid peroxidation, and neutrophil activity. At the end of each experiment, liver tissue samples were collected for histological evaluation of parenchymae markers. Statistical analysis used two-way analysis of variance (ANOVA) tests with significance set at P<.05. Vital signs significantly improved with MB infusion, irrespective of whether it was applied before or after reperfusion. Blood gas data revealed different patterns among the SHAM, MB, IR, MB-R, and R-MB groups, without statistical significance, except for favorable lactate results in the R-MB group (P<.01), which displayed greater survival. Biochemical tests did not show significant differences among the groups, whereas histological analysis revealed favorable appearances for the MB-R and R-MB groups. The MB effect lasted long after reperfusion, suggesting that improvement in the hemodynamic parameters was not based on liver integrity, but rather was possibly related to endothelial function.

The use and usefulness of information for patients undergoing anaesthesia.

Informed consent is a process rather than just simply the signing of a form. It should provide the patient with the information and understanding needed to authorize a procedure. The aim of the present study was to try to understand the patient's attitude to, and understanding of, the pre-anaesthesia informed consent (IC) document. A prospective descriptive study was made of 159 adults who attended a pre-operative consultation prior to programmed surgery at a teaching hospital. The patients were given a questionnaire on different aspects of the pre-anaesthesia IC document they had signed (ease of understanding and other aspects of the information received and expected) and five questions on how well they remembered the information given in the IC form they had read previously. A series of epidemiological variables, anaesthesia and surgery-associated risks (ASA) and whether the patients had undergone anaesthesia previously, were evaluated. The mean age of the study population was 55 (SD:19.63), with 36% over the age of 65, while 77% had not received secondary education. 21% of the patients who signed did not read the document and 14% found it difficult to understand. 89% found the information sufficient and 46% said they preferred to receive such information in written form. 64% had no or very little recall of the information they had been given, the proportion of those making this claim being in direct relation with age over 50 years and low level of studies. The findings suggest that improvements are needed in the pre-anaesthesia informed consent document so that, rather than serving as a mere legal prerequisite, it fulfils its purpose of providing the patient with the information necessary and in a clearly understood way so that he/she can authorize the proposed surgery.