Nefrología : publicación oficial de la Sociedad Española Nefrologia
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Periodic blood flow (QA) measurement is the preferred way for arteriovenous fistula (AVF) surveillance in chronic hemodialysis (HD) patients. Objectives. 1) Assess the efficacy of the temperature gradient method (TGM) on the QA determinations using the Twister™ device and to compare the functional results with the Delta-H method. 2) Evaluate the effect of blood pressure on the AVF function. Patients and method. We measured the QA non invasively in 30 AVF (24 radial and 6 brachial; mean duration 53.4 +/- 78.5 months) during HD in 30 stable patients (mean age 59.9 +/- 14.1 years, males 60 %, females 40 %; mean time on HD 37.4 +/- 40.6 months, diabetic nephropathy 20 %) by the TGM, described and validated by Wijnen et al (Kidney Int 2007;72:736). The QA was calculated from the temperature values obtained by means of the blood temperature monitor (BTM), integrated into the Fresenius Medical Care 4008-S machine, at normal and reverse configurations of the HD blood lines, with no need for a thermal bolus. The Twister™ device was used for reversing the blood lines without the need to disconnect them from the AVF lines nor to stop the blood pump. The QA was measured within the first hour of two consecutive HD sessions (the values were averaged). The mean arterial pressure MAP (diastolic pressure + 1/3 pulse pressure) was calculated simultaneous with the QA. In addition, the AVF blood flow was also determined during the same week in all patients by the Delta-H method using the Crit-Line III Monitor (ABF-mode, HemaMetrics, USA) during HD (manually switching lines). ⋯ 1) The TGM is a valuable and reproducible indicator of QA during HD. 2) The Twister™ device is useful to reduce the time for QA measurement by the TGM. 3) The AVF blood flow values obtained by the TGM and the Delta-H technique correlated highly with each other. 4) It has been shown the lack of relationship between the AVF function and the patient's blood pressure.
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Gross haematuria is a common manifestation of autosomal dominant polycystic kidney disease (ADPKD). It can be spontaneous or the result of trauma, renal calculi, tumour, or infection. Spontaneous cyst bleeding is important in this particular group of patients, since it can be prolonged by local activation of fibrinolysis by urokinase. The management of haematuria in ADPKD is usually conservative, including bed rest, blood transfusion, correction of blood disorders, and use of vasopressin and erythropoiesis-stimulating agents. In some patients, the management of gross or life-threatening haematuria may require embolisation and/or nephrectomy. Nonetheless, other methods have been tried to avoid prolonged hospitalisation and nephrectomy and preserve kidney function, such as the use of anti-fibrinolytics. Tranexamic acid was recently suggested as a tool to treat gross haematuria in ADPKD in isolated cases. ⋯ In summary, tranexamic acid can be used safely in ADPKD patients with chronic renal impairment or preserved renal function to treat severe haematuria poorly responsive to conventional therapy. Tranexamic acid can be administered orally or IV; and dose adjustment for renal impairment is important. Tranexamic acid therapy may preserve renal function in ADPKD directly, by stopping haematuria episodes, or indirectly, by preventing embolisation and/or nephrectomy. The major limitation of this study is the small sample size and the lack of an untreated control group. We suggest a prospective, randomised controlled study to confirm the efficacy of this treatment, its long-term safety, and the optimal dosage. Further larger and multicentre studies are needed to evaluate the cost-benefit ratio and the limits of this therapy in the clinical setting.
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Metformin is a drug widely used in type 2 diabetic patients. Metformin-associated lactic acidosis (MALA) in diabetic patients is rare but can be serious. However, the relationship between metformin and lactic acidosis is under debate. ⋯ We believe that MALA is a serious condition that requires prompt diagnosis and early treatment. Renal replacement therapy is not the solution for all patients, but can improve prognosis in more severe cases if started early. We should limit the use of metformin in diabetic patients with impaired renal function, although there is still controversy in the medical literature.
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The current definition and classification of acute kidney injury is based on consensus criteria (RIFLE and AKIN systems). Creatinine is the most commonly used of the recommended parameters (creatinine, glomerular filtration rate and diuresis). If the baseline value is not known, it can be calculated based on the simplified MDRD equation, assuming a filtration rate of 75 ml/min/1.73 m2 for the calculation. The aim of this study was to evaluate the diagnostic impact of using estimated baseline creatinine compared to the actual value measured in patients undergoing cardiac surgery. ⋯ The calculation of baseline creatinine using the MDRD equation overestimates the incidence of acute kidney injury after cardiac surgery, and is an inadequate method for detection when the baseline value is unknown.