The importance of low level QC for high sensitivity troponin assays

BackgroundWith the advent of the new high-sensitivity troponin assays, it is becoming critical to measure troponin accurately to low concentrations. To ensure assay performance is acceptable, appropriate QC must be run.MethodsIn addition to the routine use of commercial QC material, we prepared pools of human QC material with low troponin concentrations close to the limit of quantitation, and ran these regularly on our laboratory analysers.ResultsOver 3 years we found no drift or shift in our hs-cTnI assay. We found that only the very low concentration human QC material gave warning of precision problems with the hs-cTnI assay. At the time of the documented poor assay precision, the higher concentration QC material indicated satisfactory performance.ConclusionsChoice of QC material with an appropriate concentration is important for any assay. For hs-cTn assays, it is of particular importance to use control material with a concentration near to the limit of quantitation.     

Pilot study on the effects of high cutoff hemofiltration on the need for norepinephrine in septic patients with acute renal failure

OBJECTIVE: High cutoff hemofilters are characterized by an increased effective pore size designed to facilitate the elimination of inflammatory mediators in sepsis. Clinical data on this new renal replacement modality are lacking. DESIGN: Prospective, randomized clinical trial. SETTING: University hospital, intensive care units. PATIENTS:: Thirty patients with sepsis-induced acute renal failure. INTERVENTION: Patients were allocated to high cutoff (n = 20) or conventional (n = 10) hemofiltration in a 2:1 ratio. Median renal replacement dose was 31 mL/kg/hr. For high cutoff hemofiltration, a high-flux hemofilter with an in vivo cutoff point of approximately 60 kilodaltons was used. Conventional hemofiltration was performed with a standard high-flux hemofilter (PF11S). The impacts of high cutoff hemofiltration on the need for norepinephrine and on plasma levels and clearance rates for interleukin (IL)-6 and IL-1 receptor antagonist (IL-1ra) were analyzed. Absolute values, but also adjusted values (expressed as proportion of baseline), were analyzed. The observation period was restricted to 48 hrs. MAIN RESULTS: Apart from higher antithrombin III levels at entry into the study, main clinical and laboratory parameters were comparable between both groups. The median norepinephrine dose at entry into the study was 0.30 microg/kg/min in the high cutoff group and 0.21 microg/kg/min in the conventional hemofiltration group (p = .448). Only the high cutoff group showed a significant decline (p = .0002) in "adjusted" norepinephrine dose over time. Clearance rates for IL-6 and IL-1ra were significantly higher in the high cutoff hemofiltration group (p < .0001), which translated into a significant decline of the corresponding plasma levels (p = .0465 for IL-6; p = .0293 for IL-1ra). CONCLUSION: In this pilot study, high cutoff hemofiltration has been shown to exert a beneficial effect on the need for norepinephrine in septic patients with acute renal failure. In addition, we demonstrate that high cutoff hemofiltration is superior to conventional hemofiltration in the elimination of IL-6 and IL-1ra from the circulating blood of septic patients.     

Adrenal dysfunction in patients with renal amyloid

Amyloidosis is a multi-system disease. Renal involvement often leads to end-stage renal failure, which carries a poor prognosis. This paper reports the adrenal status of 22 patients with renal amyloid who were considered for or who had been commenced on renal replacement therapy. Twelve patients were considered or found to have AA amyloid and the remaining 10 had AL amyloid. Of 16 patients tested, seven demonstrated an abnormal response to a synacthen test. Four patients died at Addisonian crisis and hypo-adrenalism probably contributed to the deaths of a further two patients. Amyloid deposition was found in the adrenal glands in seven patients who died of systemic amyloidosis and renal failure. It is recommended that all patients with renal amyloid should have an assessment of adrenal function performed and if abnormal replacement steroid therapy should be commenced.     

How to feed patients with renal dysfunction

Renal dysfunction is common in critically ill patients and its presence has, in the past, posed serious challenges to nutritional support. Such challenges were due to the increased azotemia induced by protein or amino acid administration, the fluid overload caused by the administration of nutrients, and the difficulties associated with the control of these complications by means of conventional dialytic techniques.The development and increasing application of continuous renal replacement therapy has removed such concerns, because control of azotemia and fluid balance can be predictably and reliably achieved in all patients. Accordingly, the presence of renal failure should in no way influence the amount or type of nutritional support administered to a critically ill patient. We recommend that approximately 30-35 kCal/kg/d be administered enterally and begun within the first few hours of admission to the intensive care unit, and that protein intake be kept in the 1.5-2 g/kg/d range.Accumulating evidence also suggest that immune-enhancing enteral preparations decrease the duration of hospital stay, the number of infections, and perhaps mortality. Such preparations should be used in these patients. Finally, adequate vitamin and trace element supplementation is recommended to counterbalance the decrease in antioxidants and the loss of some vitamins during continuous renal replacement therapy. Available evidence suggests that if these steps are applied as part of a protocol-based approach to the nutritional support of patients with renal failure, morbidity and perhaps mortality can be significantly decreased.     

Thrombocytopenia and anemia caused by a persistent high linezolid concentration in patients with renal dysfunction

It has been proposed that it is not necessary to adjust the dose of linezolid (LZD) in patients with reduced renal function. However, significantly lower platelet counts and hemoglobin levels have been reported in such patients compared to those in patients with normal renal function. This suggests that the appropriate dose and administration method for LZD are yet to be established in patients with renal dysfunction. The subjects in this study were patients with renal dysfunction who developed adverse effects of thrombocytopenia and anemia during treatment with LZD. We investigated the association of these adverse effects with the blood LZD concentration and the area under the concentration–time curve from zero to 24 h (AUC_0–24), determined using a one-compartment Bayesian model (n = 20). The measured blood LZD concentration was significantly higher than the predicted concentration in a population pharmacokinetics approach (p < 0.01), and severe thrombocytopenia developed as the blood LZD concentration increased. The platelet count and hemoglobin level decreased as the AUC_0–24 of LZD increased in patients with renal dysfunction, and the correlations were significant: r = 0.593 and r = 0.783, respectively (p < 0.01). These findings suggest that LZD administered to patients with renal dysfunction may reach a high blood level and subsequently increase the AUC_0–24, which may then induce adverse effects of severe thrombocytopenia and anemia.     

Itraconazole pharmacokinetics in patients with renal dysfunction.

The single-dose pharmacokinetics of 200 mg of oral itraconazole were studied in seven uremic patients, seven patients treated by hemodialysis, and five patients treated by continuous ambulatory peritoneal dialysis. Plasma concentration-versus-time profiles showed wide intersubject variation. This study could not demonstrate any significant effect of renal dysfunction and hemodialysis or continuous ambulatory peritoneal dialysis treatment upon the pharmacokinetics of itraconazole, and firm conclusions concerning dosing in such patients should await confirmation of our data in a larger patient population.     

肾功能不全患者心脏手术的围术期管理

目的:总结肾功能不全患者心脏手术围手术期管理的临床经验.方法:对1998年8月至2009年3月中国医科大学第一医院院收治的24例(其中18例为冠心病,4例为风湿性心脏病,1例为主动脉瓣病变合并冠心病, 1例为二尖瓣病变合并冠心病)合并肾功能不全患者心脏手术围术期治疗进行总结.结果:18例冠心病患者中10例在体外循环下完成手术,8例在非体外循环下完成手术.2例风湿性心脏病患者行双瓣置换术,2例行二尖瓣置换术.1例行冠状动脉旁路移植术加主动脉瓣置换术,1例行冠状动脉旁路移植加二尖瓣置换术.术后均进行连续性肾脏替代疗法(CRRT),透析6 h后患者心率、中心静脉压、肌酐和尿素氮较未透析时明显下降(P ＜ 0.05),而平均动脉压、动脉血氧分压较未透析时明显升高(P ＜ 0.05).围术期3例患者死亡, 3例患者放弃治疗, 其余18例患者中有5例改为内科规律透析治疗,10例患者肾功能恢复到术前水平出院后尿量恢复未再透析治疗,术后随访(28.5 ± 25.4)个月,心脏症状均消失,生存质量明显提高. 结论:CRRT是肾功能不全患者心脏术后围术期治疗的重要手段.     

Rapid,high sensitivity,point-of-care test for cardiac troponin based on optomagnetic biosensor

BackgroundWe present a prototype handheld device based on a newly developed optomagnetic technology for the sensitive detection of cardiac troponin I (cTnI) in a finger-prick blood sample with a turnaround time of 5 min.MethodsThe test was completed in a compact plastic disposable with on-board dry reagents and superparamagnetic nanoparticles. In our one-step assay, all reaction processes were precisely controlled using electromagnets positioned above and below the disposable. Nanoparticle labels (500 nm) bound to the sensor surface via a sandwich immunoassay were detected using the optical technique of frustrated total internal reflection.ResultsA calibration function measured in plasma demonstrates a limit of detection (mean of blank plus 3-fold the standard deviation) of 0.03 ng/mL cTnI. A linear regression analysis of the region 0.03–6.5 ng/mL yields a slope of 37 ± 4, and a linear correlation coefficient of R² = 0.98. The measuring range could be extended substantially to 100 ng/mL by simultaneously imaging a second spot with a lower antibody concentration.ConclusionsThe combination of magnetic particles and their fine actuation with electromagnets permits the rapid and sensitive detection of cTnI. Because of the potential high analytical performance and ease-of-use of the test, it is well suited for demanding point-of-care diagnostic applications.     

Using high sensitivity cardiac troponin values in patients with SARS-CoV-2 infection (COVID-19): The Padova experience

BackgroundThe spectrum of Coronavirus Disease 2019 (COVID-19) is broad and thus early appropriate risk stratification can be helpful. Our objectives were to define the frequency of myocardial injury using high-sensitivity cardiac troponin I (hs-cTnI) and to understand how to use its prognostic abilities.MethodsRetrospective study of patients with COVID-19 presenting to an Emergency Department (ED) in Italy in 2020. Hs-cTnI was sampled based on clinical judgment. Myocardial injury was defined as values above the sex-specific 99th percentile upper reference limits (URLs). Most data is from the initial hospital value.Results426 unique patients were included. Hs-cTnI was measured in 313 (73.5%) patients; 85 (27.2%) had myocardial injury at baseline. Patients with myocardial injury had higher mortality during hospitalization (hazard ratio = 9 [95% confidence interval (CI) 4.55–17.79], p < 0.0001). Multivariable analysis including clinical and laboratory variables demonstrated an AUC of 0.942 with modest additional value of hs-cTnI. Myocardial injury was associated with mortality in patients with low APACHE II scores (<13) [OR (95% CI): 4.15 (1.40, 14.22), p = 0.014] but not in those with scores > 13 [OR (95% CI): 0.48 (0.08, 2.65), p = 0.40]. Initial hs-cTnI < 5 ng/L identified 33% of patients that were at low risk with 97.8% sensitivity (95% CI 88.7, 99.6) and 99.2% negative predictive value. Type 1 myocardial infarction (MI) and type 2 MI were infrequent.Conclusionshs-cTnI at baseline is a significant predictor of mortality in COVID-19 patients. A value < 5 ng/L identified patients at low risk.     

血液高凝状态加重糖尿病肾病肾功能障碍

目的 探讨糖尿病肾病患者血液高凝状态与肾功能的关系。方法 46例伴有肾病综合征的糖尿病肾病患者,以24h内生肌酐清除率分为高（H）、中（M）和低（L）三组,并对其中14例实施华法林治疗。系统检测凝血、纤溶及肾功指标。结果 伴随肾病进展,凝血活性进一步亢进;华法林治疗改善高凝状态后,可降低肾病恶化速度。结论 血液高凝状态是糖尿病肾病患者肾功能障碍的原因之一。     

肾功能障碍病人的术前评估与准备

肾功能障碍一般涉及肾小球和肾小管功能异常两个方面，绝大多数肾功能障碍同时有肾小球和肾小管功能异常，但程度不一。肾功能轻度或中度障碍的病人，可能没有明显的临床迹象，但麻醉和手术导致急性功能障碍甚至肾衰的危险性明显增加。因此，术前应根据病史、体检、尿量及一些生化检查了解病人肾功能，对疑有肾脏疾病、肾功能损害的患者应作详细的肾。     

Negotiating renal dysfunction when treating patients with heart failure

Introduction: Chronic kidney disease (CKD) is one of the most prevalent comorbidities in HF, and no specific treatment is still available for the so-called cardiorenal syndrome.

Areas covered: The aim of this review is to describe the interaction of heart and kidney function and the consequences of cardiorenal syndrome, focusing on the use of available therapeutics.

Expert commentary: The presence of CKD has been associated with adverse outcomes in HF regardless of ejection fraction. On the other hand, cardiovascular events are the most common causes of morbidity and mortality among CKD patients, reflecting the close pathophysiological crosstalk between these organs. Multiple mechanisms are involved in the development of cardiorenal syndrome, including hemodynamic, neurohormonal and inflammatory mediators. The management of several HF drugs is a challenge in the presence of CKD mainly due to blunted diuretic response and increased risk of worsening of kidney function. Therefore, finding a balance between the optimization of cardiac and renal outcomes is a real negotiation in the everyday clinical practice.     

伴发肾功能不全的多器官功能障碍综合征患者的临床特征及预后

目的　探讨伴发肾功能不全的多脏器功能障碍综合征 (MODS)患者的临床特征及预后。方法　对一综合性ICU中 6 0例MODS患者的临床特征进行回顾性分析 ,并比较了入院时APACHEⅡ评分、序贯器官衰竭估计 (sequentialorganfailureassessment,SOFA)评分对预后的预测作用。结果　 6 0例MODS患者中发生肾功能不全 4 5例 (75 % ) ,未发生肾功能不全 15例 (2 5 % ) ,二组比较病死率无差异 ,但发生肾功能不全组器官衰竭个数、最大SOFA评分明显高于未发生肾功能不全组 (P <0 0 1)。在发生肾功能不全的患者中存活组与死亡组临床特征比较显示 ,两组在少尿、休克的存在、行机械通气治疗、器官衰竭的个数、入院后肾功能不全出现的时间、入院肾SOFA评分、肾最大SOFA评分及总最大SOFA评分差异有显著意义(P <0 0 5 )。少尿组与非少尿组患者临床特征比较显示少尿组患者病死率、器官衰谒个数、总最大SOAF评分、肾最大SOFA评分明显高于非少尿组 (P <0 0 1)。结论　在MODS中肾脏损害较普遍。伴发肾功能不全的MODS患者中影响预后的因素主要有少尿、休克的存在、行机械通气治疗、器官衰竭的个数、迟发的肾功能衰竭。SOAF评分对估计MODS患者的病情及预测预后具有良好的临床应用价值。     

慢性肾功能衰竭维持性血液透析患者血清心肌肌钙蛋白的变化

目的观察慢性肾功能衰竭(CPF)维持性血液透析患者心肌肌钙蛋白(cTnI)的异常变化。方法应用双抗夹心酶联免疫吸附法(FLISA)检测115例维持性血液透析患者和64例正常人的cTnI。结果 慢性肾功能衰竭组的血清cTnI水平为(0.20±0.52)ng/ml,显著高于健康对照组(0.03±0.05)ng/ml(P<0.05)。115例慢性肾功能衰竭维持性血液透析患者中31(27.0％)例有不同程度的胸闷、心悸等症状;有症状患者血清cTnI为(0.49±0.93)ng/ml,显著高于无症状患者(0.09±0.11)ng/ml,P相似文献