Comparison of different techniques of central venous pressure measurement in mechanically ventilated critically ill patients.

BACKGROUND: Several techniques exist for measuring central venous pressure (CVP) but little information is available about the accuracy of each method. The aim of this study was to compare different methods of CVP measurements in mechanically ventilated patients. METHODS: CVP was measured in mechanically ventilated patients without spontaneous breathing using four different techniques: 1) end expiratory CVP measurement at the base of the" c" wave (CVPMEASURED), chosen as the reference method; 2) CVP measurement from the monitor averaging CVP over the cardiac and respiratory cycles (CVPMONITOR); 3) CVP measurement after a transient withdrawing of mechanical ventilation (CVPNADIR); 4) CVP measurement corrected for the transmitted respiratory pressure induced by intrinsic PEEP (calculated CVP: CVPCALCULATED). Bias, precision, limits of agreement, and proportions of outliers (difference > 2 mm Hg) were determined. RESULTS: Among 61 included patients, 103 CVP assessments were performed. CVPMONITOR bias [-0.87 (1.06) mm Hg] was significantly different from those of CVPCALCULATED [1.42 (1.07), P < 0.001 and CVPNADIR (1.04 (1.29), P < 0.001]. The limits of agreement of CVPMONITOR [-2.96 to 1.21 mm Hg] were not significantly different to those of CVPNADIR (-1.49 to 3.57 mm Hg, P = 0.39) and CVPCALCULATED (-0.68 to 3.53 mm Hg, P = 0.31). The proportion of outliers was not significantly different between CVPMONITOR (n = 5, 5%) and CVPNADIR (n = 9, 9%, P = 0.27) but was greater with CVPCALCULATED (n = 16, 15%, P = 0.01). CONCLUSIONS: In mechanically ventilated patients, CVPMONITOR is a reliable method for assessing CVPMEASURED Taking into account transmitted respiratory pressures, CVPCALCULATED had a higher proportion of outliers and precision than CVPNADIR.

Population pharmacokinetics of linezolid in critically ill patients on renal replacement therapy: comparison of equal doses in continuous venovenous haemofiltration and continuous venovenous haemodiafiltration.

OBJECTIVES: Few data are available to guide linezolid dosing during renal replacement therapy. The objective of this study was to compare the population pharmacokinetics of linezolid during continuous venovenous haemofiltration (CVVHF, 30 mL/kg/h) and continuous venovenous haemodiafiltration (CVVHDF, 15 mL/kg/h + 15 mL/kg/h). METHODS: Patients requiring linezolid 600 mg iv every 12 h and CVVHF or CVVHDF were eligible for this prospective study. Seven blood samples were collected over one dosing interval and analysed by a validated chromatographic method. Population pharmacokinetic analysis was undertaken using Pmetrics. Monte Carlo simulations evaluated achievement of a pharmacodynamics target of an AUC from 0-24 h to MIC (AUC0-24/MIC) of 80. RESULTS: Nine CVVHDF and eight CVVHF treatments were performed in 13 patients. Regimens of CVVHDF and CVVHF were similar. A two-compartment linear model best described the data. CVVHDF was associated with a 20.5% higher mean linezolid clearance than CVVHF, without statistical significance (P = 0.39). Increasing patient weight and decreasing SOFA score were associated with increasing linezolid clearance. The mean (SD) parameter estimates were: clearance (CL), 3.8 (2.2) L/h; volume of the central compartment, 26.5 (10.3) L; intercompartmental clearance constants from central to peripheral, 8.1 (12.1) L/h; and peripheral to central compartments, 3.6 (4.0) L/h. Achievement of pharmacodynamic targets was poor for an MIC of 2 mg/L with the studied dose. CONCLUSIONS: During CVVHF and CVVHDF, there is profound pharmacokinetic variability of linezolid. Suboptimal achievement of therapeutic targets occurs at the EUCAST breakpoint MIC of 2 mg/L using 600 mg iv every 12 h.

[Use of indicators of fluid responsiveness in septic shock: a survey in public emergency departments]. / Indices de réponse au remplissage vasculaire lors de la prise en charge d'un choc septique : utilisation par les médecins urgentistes.

INTRODUCTION: Fluid therapy is one of the major elements of severe sepsis and septic shock management. A systematic initial fluid bolus is recommended before evaluation of left ventricular filling pressure by the use of indicators of fluid responsiveness, preferentially dynamic ones. A massive fluid therapy could be damaging for the patient. Dynamic indicators of fluid responsiveness are not often relevant in the emergency department. This study was aimed to evaluate the use of indicators of fluid responsiveness by emergency practitioners during septic shock management. STUDY DESIGN: Cross sectional survey using anonymous self-questionnaire. METHODS: We included all practitioners working in public emergency department of Languedoc-Roussillon (France). Primary-end point was the use of one indicator of fluid responsiveness at least. Uni- and multivariate analysis was conducted to find associated factors. RESULTS: Of 232 practitioners included, we collected 149 questionnaires (response rate=64%). Hundred and eight practitioners (72% [64-79%]) used at least one indicator of fluid responsiveness. Fifty-six practitioners (38% [30-46%]) used echocardiography, 54 practitioners (36% [29-44%]) used blood lactate concentration, 45 practitioners (30% [23-38%]) used passive leg raising. The use of indicators of fluid responsiveness is associated with easy access to echography device (odd ratio=2.94 [1.16-7.62], P=0.03). CONCLUSION: Emergency practitioners use preferentially less invasive and less time-consuming indicators of fluid responsiveness.