Measurement of the international normalized ratio (INR) in hemodialysis patients with heparin-locked central venous catheters: evaluation of a novel blood sampling method.

BACKGROUND: Accurate measurement of the international normalized ratio (INR) may be difficult in hemodialysis (HD) patients with heparin-locked central catheters. Blood contamination with locking solutions may interfere with INR measurement when samples are collected directly from the catheter. METHODS: The aim of our study was to evaluate a novel sampling method for the measurement of INR in HD patients with heparin-locked central catheters. This novel method consists of measuring the INR directly from the dialysis circuit (arterial bloodline sample port) after 1 hr of treatment regardless of heparin administration during dialysis. We compared this method to the gold standard (peripheral venipuncture prior to dialysis) using the paired t-test. We included 30 patients (23 with warfarin therapy and 7 without). RESULTS: INRs obtained using the novel sampling method were only minimally overestimated compared to venipuncture values (mean INR overestimation: 0.2 +/- 0.2). This overestimation was not clinically significant and did not lead to changes in warfarin prescription for any of the patients. Correlation tests confirmed the influence of heparin administration on INR overestimation (R=0.4; p=0.05). This influence was present mostly among patients receiving more than 100 Units/kg of heparin during their treatment. CONCLUSION: This novel sampling technique provides a convenient and simple method of monitoring INR among HD patients.

Pentastarch 10% (250 kDa/0.45) is an independent risk factor of acute kidney injury following cardiac surgery.

UNLABELLED: OBJECTIVE, DESIGN AND PATIENTS: The risk of acute kidney injury (AKI) associated with hydroxyethyl starch may be limited to higher molecular weight agents. We retrospectively evaluated the risk of AKI using pentastarch 10% (250 kDa, 0.45) in a random cohort of 563 patients operated for a cardiac surgery at a university hospital. MEASURES: We assessed previously identified preoperative, perioperative, and postoperative risk factors, and the volume of pentastarch given until the end of the first postoperative day. We defined AKI by a 50% rise in serum creatinine within 4 days after surgery. Different propensity adjustment methods were used to further assess the selection bias. RESULTS: Fifty-four (10%) patients developed AKI. Risk factors of AKI were age, female gender, preoperative creatinine clearance, hypertension, diuretic use, left ventricular ejection fraction, valvular surgery, duration of extracorporeal circulation, duration and dose of postoperative vasopressor support, and the number of red blood cells and fresh frozen plasma transfusions. Patients with AKI received 16 +/- 9 mL/kg of pentastarch as opposed to 10 +/- 7 mL/kg in controls (p < 0.001). Pentastarch remained independently predictive of AKI, with an adjusted odds ratio per mL/kg of 1.08 (95% confidence interval 1.04-1.12, p = 0.001). This risk was dose-dependent, and the optimal cutoff volume predicting AKI was 14 mL/kg. Different propensity adjustment methods were tested, and pentastarch as a risk factor of AKI was identified. CONCLUSIONS: This study identified a dose-dependent risk of AKI with pentastarch following cardiac surgery, given until the end of the first postoperative day.