Determination of acetaminophen and its main metabolites in urine by capillary electrophoresis hyphenated to mass spectrometry.

In this study, a capillary electrophoresis-tandem mass spectrometry method combining efficient separation and sensitive detection has been developed and validated, for the first time, to quantify acetaminophen and five of its metabolites in urine samples. Optimization of the method has led us to perform detection in positive ESI mode using MeOH-ammonium hydroxide (0.1%) (50:50, v/v) as sheath liquid. Moreover, optimal separation has been obtained in less than 9 min after anodic injection, using an ammonium acetate solution (40 mM, pH 10) as BGE. It was shown that the dilution solvent and the dilution factor to use for sample preparation are critical parameters to avoid peak splitting, to gain in sensitivity and then to obtain an effective analysis method. While a 200-fold factor dilution was shown to be suitable for quantitation of acetaminophen, acetaminophen mercapturate, acetaminophen sulfate and acetaminophen glucuronide, a 20-fold dilution was finally selected for methoxy-acetaminophen and 3-methylthioacetaminophen analysis, thus requiring two successive analyses to be carried out in order to quantify all metabolites. Hyphenation of CE with MS/MS versus UV permits to improve LOQ (10-20-fold factor with respect to previous works for acetaminophen, acetaminophen sulfate and acetaminophen glucuronide). Moreover, use of CE versus HPLC, permits to quantify two additional metabolites, i.e. 3-methylthio-acetaminophen and methoxy-acetaminophen. The method has been validated using the accuracy profile approach with a total error (accuracy) included in the ± 20% range. Thereby, the method allows the quantitation of acetaminophen and acetaminophen mercapturate in the range (0.1-1 mg mL-1), and of acetaminophen sulfate, methoxy-acetaminophen, acetaminophen glutathione and 3-methylthio-acetaminophen in the ranges (0.5-5 mg mL-1), (0.025-0.4 mg mL-1), (9.22-30 mg mL-1) and (0.073-0.4 mg mL-1), respectively. The method was finally applied to the analysis of urine samples of eighteen patients belonging to three different inclusion groups of the ongoing clinical trial, demonstrating that the method is suitable to highlight different metabolic profiles. This work will be subsequently extended to the analysis two hundred and seventy urine samples from patients included in a clinical trial dedicated to the study of acetaminophen metabolism changes after hepatic resection.

Effect of pharmacological preconditioning with sevoflurane during hepatectomy with intermittent portal triad clamping.

BACKGROUND: During hepatectomy, intermittent portal triad clamping (IPC) reduces ischemia-reperfusion injuries. Pharmacological preconditioning with sevoflurane revealed similar properties. The aim of the study was to evaluate the combination of a sevoflurane preconditioning regimen with IPC on ischemia-reperfusion injuries. METHODS: Three regimens of anesthesia were applied: group SEV with continuous application of sevoflurane, group PRO with continuous propofol infusion and group PC where continuous propofol was substituted by sevoflurane (adjusted to reach MAC∗1.5) for 15 min before IPC. Endpoints were the values of AST and ALT, factor V, prothrombin time, bilirubinemia over the 5-postoperative days (POD), morbidity and mortality at POD30 and POD90. RESULTS: The ALT values at POD5 were lower in the PC group (n = 27) 74 (48 -98) IU/L compared to PRO (n = 26) and SEV (n = 67) respectively 110 (75 -152) and 100 (64 -168) IU/L (p = 0.038). The variation of factor V compared to preoperative values was less important in the PC and SEV groups respectively -14% and -16% vs -30% (PRO) (p = 0.047). CONCLUSION: Our study suggests that sevoflurane attenuates ischemia-reperfusion injuries on liver function, compared to propofol, without benefit for a specific regimen of pharmacological preconditioning when IPC is applied.

Effect of insulin infusion line on glycaemic variability in a perioperative high dependency unit (HDU): a prospective randomised controlled trial.

BACKGROUND: Glucose control is an important issue in post-operative patients. The objective here was to compare two insulin infusion lines by syringe pumps to assess the impact of medical devices on glycaemic variability in surgical patients under intensive insulin therapy. This open, prospective, single-centre randomised study was conducted in a fifteen-bed perioperative high dependency unit (HDU) in a university hospital. In total, 172 eligible patients receiving insulin therapy agreed to participate in the study. Subcutaneous continuous glucose monitoring was set up for all patients and an optimised system with a dedicated insulin infusion line for half of the patients. RESULTS: Eighty-six patients were infused via the optimised infusion line and 86 patients via the standard infusion line. No significant difference was found according to the glycaemic lability index score [mean difference between groups (95% CI): -0.09 (-0.34; 0.16), p = 0.49 after multiple imputation]. A glucose control monitoring system indicated a trend towards differences in the duration of hypoglycaemia (blood glucose level below 70 mg dl-1 (3.9 mmol l-1) over 1000 h of insulin infusion (9.7 ± 25.0 h in the standard group versus 4.4 ± 14.8 h in the optimised group, p = 0.059) and in the number of patients experiencing at least one hypoglycaemia incident (25.7 vs. 12.9%, p = 0.052). Time in the target range was similar for both groups. CONCLUSIONS: The use of optimised infusion line with a dedicated insulin infusion line did not reduce glycaemic variability but minimised the incidence of hypoglycaemia events. The choice of the medical devices used to infuse insulin seems important for improving the safety of insulin infusion in perioperative HDU.