A noninvasive strategy for screening prospective blood donors for anemia

BACKGROUND: The reliability of capillary hemoglobin (Hb) as an indicator for eligibility to donate blood is discussed controversially. Therefore, a noninvasive alternative with acceptable predictive values was established and evaluated. STUDY DESIGN AND METHODS: Donor candidates were selected according to their Hb level. The first donation was performed 6 weeks after this selection step. A venous blood sample was collected from all donors at the end of their donation and a postdonation Hb determination was performed. Donors with acceptable postdonation Hb values were permitted to donate next time without any predonation Hb measurement. Donors with low postdonation Hb values were permitted to donate only after a venous Hb measurement had shown an acceptable value. Sensitivity and specificity were determined by comparing the gold standard (i.e., venous Hb measurement) with the presented method of Hb estimation for 19,534 donors. RESULTS: Taking the postdonation Hb as an indicator for eligibility saved 97 percent of donors from being tested unnecessarily by capillary Hb measurement. This procedure resulted in a specificity of 92.6 percent and a sensitivity of 37.9 percent for Hb cutoff levels of 135 and 125 g per L for men and women, respectively. The sensitivity increased rapidly to 100 percent for Hb levels below 105 g per L. The average deviation from true Hb level was 6 g per L. CONCLUSION: The presented noninvasive method distinctly saves time and expenditure without endangering blood donors.     

Evaluation of a new flow cytometric HPA 1a screening method. A rapid and reliable tool for HPA 1a screening of blood donors and pregnant women.

We have evaluated a flow cytometric screening method for identification of HPA la negative individuals, using a commercially available monoclonal anti-CD61 antibody specific for the HPA 1a allotype, and compared the method with an ELISA based method for HPA la phenotyping and two methods for PCR genotyping. HPA 1a phenotyping by fluorochrome conjugated monoclonal anti-HPA la and analysis by flow cytometry is a rapid, reliable and inexpensive technique, suitable for screening purposes.     

Iron and erythropoietin measurement in autologous blood donors with anemia: implications for management

Background : The importance of autologous blood donation for elective surgery is recognized, and the method is being used at many hospitals. Not all patients are able to deposit a sufficient amount of blood before surgery because they cannot recover rapidly enough from phlebotomy-induced anemia. The ability to donate sufficient blood for autologous use was studied in patients who are particularly susceptible to phlebotomy-induced anemia. Study Design and Methods : Of 840 patients who donated blood for autologous use in elective surgery from November 1987 through May 1993, 20 with rheumatoid arthritis, 24 with iron deficiency anemia, and 37 aged 65 years and above with normocytic anemia were compared with 24 nonanemic elderly patients who donated a total of 1000 mL of blood for autologous use. Patients received iron sulfate orally and donated blood once a week until operation. Results : The amount of blood collected before surgery per control patient was more than that in others. Consequently, there was a tendency to allogeneic blood transfusion in patients with rheumatoid arthritis or elderly patients. The ferritin levels in controls and in patients with iron deficiency anemia during the donation period were almost within the normal range in spite of iron supplementation, which implied a good utilization of iron sulfate for erythropoiesis. On the other hand, the rise in ferritin levels in the elderly and in patients with rheumatoid arthritis suggested inappropriate iron availability for erythropoiesis and resulted in an increase in iron storage. Since an adequate endogenous erythropoietin response to phlebotomy-induced anemia was not observed in these patients, impaired erythropoietin production was considered one of the reasons for anemia. Conclusion : Patients with iron deficiency anemia are able to continue donating blood for autologous use so long as they have sufficient iron supplementation. However, the elderly or those with rheumatoid arthritis occasionally fail to donate a sufficient volume of blood before surgery as a result of phlebotomy-induced anemia, which is caused in turn by impaired erythropoietin production.     

The spot test is not a reliable screening procedure for mucopolysaccharidoses

To check the reliability of the Ames MPS paper spot test, which is based on the Azure A dye, we sent a series of urine samples to three laboratories where the spot test is part of the metabolic screening for mucopolysaccharidoses. In these laboratories false-negative results ranged between 19% and 35% and false-positive results ranged between 12% and 29% of all samples submitted. In contrast, the quantitative dimethylmethylene blue test (Clin Chem 1989;35:1472-7) detected an increased glycosaminoglycan content in all urine samples from mucopolysaccharidosis patients and gave no false-positive results. In the latter procedure, glycosaminoglycan content is expressed per millimole of creatinine, and age-dependent reference values are used. We conclude that the Ames spot test and other spot tests are unreliable as a screening procedure for mucopolysaccharidoses and should not be used to screen for these diseases.     

Evaluation of hemoglobin of blood donors deferred by the copper sulphate method for hemoglobin estimation.

INTRODUCTION: The copper sulphate (CuSO4) specific gravity test for Hb screening tends to give inappropriate failures. This prompted us to compare it with alternate screening methods. AIM: To study the impact of inaccuracy of CuSO4 method on donor deferral. METHODS: Capillary and venous blood samples of 400 potential blood donors failing the primary Hb screening using appropriately standardized CuSO4 test (specific gravity 1.053) were tested by Hemocue photometer, the Hb colour scale, Cyanmethemoglobin method as well as the automated hematology analyser, which was considered as the standard reference method. RESULTS: One hundred and sixteen donors (29%) who failed the CuSO4 test had true Hb levels >12.5 g/dl. The Hb levels of 131 (32.8%) deferred donors were between 12 and 12.5 g/dl. The sensitivity of Hemocue, Hb colour scale and Cyanmethemoglobin was 99%, 97% and 96% and their specificity was 45%, 93% and 46%, respectively. The positive predictive values (PPV) of Hemocue and Cyanmethemoglobin methods were low (43% and 44%, respectively) but their negative predictive values (NPV) were high (99%, and 97%, respectively). The Hb colour scale had an overall best performance with a PPV of 96% and NPV of 95%. CONCLUSION: The Hemoglobin colour scale which is inexpensive, convenient for field testing and has the overall best performance, is the most suitable for donor Hb screening. Since its readability is 12 g/dl, lowering the donor Hb threshold to 12 g/dl should be actively considered.     

Accuracy of noninvasive and invasive point-of-care total blood hemoglobin measurement in an outpatient setting

Objective: The purpose of this study was to determine the accuracy of noninvasive hemoglobin measurement using pulse CO-oximetry (Pronto? SpHb?, Masimo Corp.) and a commonly used, invasive, point-of-care, automated spectrophotometer (HemoCue 201+?, HemoCue, Inc.), in comparison with hemoglobin measurements obtained from a laboratory hematology analyzer (measuring total blood hemoglobin) in the outpatient setting. Methods: Adult patients presenting to an outpatient research clinic were tested for total blood hemoglobin measurement by 3 methods: noninvasive pulse CO-oximetry (SpHb?), finger-stick blood sample on a point-of-care device, and venous sample on a laboratory hematology analyzer (reference device). Bias and standard deviation (SD) of SpHb? and HemoCue 201+? compared with the values obtained with the laboratory hematology analyzer were calculated and Bland-Altman graphs were generated. Results: Samples from 152 subjects were assessed (average age, 46 years; 69% female). The bias ± SD compared with the reference method was -0.5 ± 1.0 g/dL for SpHb? and 0.3 ±1.0 g/dL for HemoCue 201+?. The Bland-Altman plots assessing agreement of the test methods to the reference method had limits of agreement of -2.5 to 1.5 g/dL for SpHb? and -1.7 to 2.3 g/dL for HemoCue 201+?. A noninvasive measurement could not be obtained in 4 subjects after 2 attempts (2.5% failure rate), whereas the HemoCue 201+? measurements were obtained for all subjects. Conclusion: Noninvasive SpHb? testing had bias and SD similar to those of HemoCue 201+?. Because SpHb? measurement is noninvasive, it may offer additional patient and provider benefits.     

Oscillometric blood pressure measurement: a simple method in screening for peripheral arterial disease

Blood pressure at the ankle level is a reliable indicator of peripheral arterial disease (PAD) and the ankle brachial index (ABI) is a useful non-invasive screening tool for the early detection of atherosclerosis. In the first part of the study, systolic blood pressures obtained by oscillometry and plethysmography were compared in 80 subjects referred for possible vascular disease. In the second part of the study, 31 general practitioners enrolled 1258 consecutive patients aged more than 60 years. ABI was estimated by oscillometry. Patients with an ABI lower than 0.9 were referred to the local hospital for standardized measurements. In the first part, oscillometry showed a sensitivity of 97% and a specificity of 62% with a positive and negative predictive value of 71% and 96%, respectively. In the second part, significant PAD was found in 111 cases corresponding to a prevalence of 12.2%. In this population, the oscillometry showed a positive predictive value of 47%. The presence of PAD was significantly correlated to exercise related leg pain, a diagnosis of hypertension and smoking, whereas no correlation could be found with a diagnosis of heart disease, stroke, or with the presence of diabetes. The prevalence of PAD was sufficiently high in subjects over the age of 60 years to warrant screening. The ankle brachial index based on measurements with an oscillometric device was shown reliable in the exclusion of PAD, thereby fulfilling an important criterion for the use in screening.     

Evaluation of measurement sites for noninvasive blood glucose sensing with near-infrared transmission spectroscopy.

Six putative measurement sites were evaluated for noninvasive sensing of blood glucose by first-overtone near-infrared spectroscopy. The cheek, lower lip, upper lip, nasal septum, tongue, and webbing tissue between the thumb and forefinger were examined. These sites were evaluated on the basis of their chemical and physical properties as they pertain to the noninvasive measurement of glucose. Critical features included the effective optical pathlength of aqueous material within the tissue and the percentage of body fat within the optical path. Aqueous optical paths of 5 mm are required to measure clinically relevant concentrations of glucose in the first-overtone region. All of the tested sites met this requirement. The percentage of body fat affects the signal-to-noise ratio of the measurement and must be minimized for reliable glucose sensing. The webbing tissue contains a considerable amount of fat tissue and is clearly the worse measurement site. All other sites possess substantially less fat, with the least amount of fat in tongue tissue. For this reason, the tongue provides spectra with the highest signal-to-noise ratio and is, therefore, the site of choice on the basis of spectral quality.     

血红蛋白测试仪在献血者初筛中的应用及效果评价

目的 探讨采供血机构所使用的血红蛋白微片法测定血红蛋白含量(Hbg/L)的实际意义和效果评价.方法 分别采用氰化高铁血红蛋白(HiCN)法、硫酸铜比重法、血红蛋白微片法、血球计数仪检测法,测定血红蛋白含量为高、中、低三种浓度的样本,各50～60次;并对500份随机献血者血样用硫酸铜比重法、血球计数仪及血红蛋白微片法同时进行检测,使用SPSS统计软件对测定结果 进行统计分析.结果 除硫酸铜比重法外,其他三种方法 的检测结果 均存在统计学差异,但对仪器进行校验后的再次检测结果 表明,微片法和血球计数仪的检测结果 不存在统计学差异.结论 当计量局无法对采供血机构所使用的计量仪器进行强检时,我们可以通过其他方法 对仪器进行对比,以达到对仪器进行校验的目的 .血红蛋白微片法测试血红蛋白含量(Hb)可代替硫酸铜法用于流动采血车上献血者的血红蛋白初筛实验.     

Food antibodies, intestinal permeability and HLA status in IgA deficient blood donors identified by a new rapid screening test

Circulating food antibodies, intestinal permeability and HLA status were studied in twelve blood donors previously identified as being selectively IgA deficient from screening 10,000 donations by means of a latex agglutination inhibition test, and confirmed by laser nephelometry. Assessment of intestinal function also included clinical history and standard laboratory tests. The donors proved to be healthy with no evidence of autoimmune disease or allergy. Nine donors (75%) had precipitins to food antigens. None had increased intestinal permeability as measured by the cellobiose/mannitol absorption test. HLA-A, B and DR antigen distribution was normal. IgG sub-class distribution was normal with the exception of an IgG2 level slightly below normal in one donor (0.9 g/l). An unexpected finding was a return of IgA levels to normal in four donors (33%) within 6 months.     

献血者HCV RNA实时荧光定量PCR方法的建立

目的建立快速检测献血者中丙型肝炎病毒(hepatitis C virus,HCV)感染的方法。方法利用体外转录制备的HCV RNA转录体进行病毒RNA抽提方法及抽提效率的比较;将RNA转录体与正常血清进行不同数目的混合,对最佳混合标本数进行了摸索;建立HCV荧光定量PCR方法(fluorescence quantitative PCR,FQ-PCR),并对献血者进行混合标本HCV核酸检测。结果确定了比较理想的病毒RNA抽提方法;用于HCV核酸检测的混合标本数为24例;建立的荧光定量PCR方法能最低检测出10个copies/ml;采取24例混合血标本方法,FQ-PCR检测HCV RNA,576例ELISA检测HCV阴性的献血者未检测出HCV RNA。结论初步建立了献血者HCV感染的混合标本荧光定量PCR检测方法。     

Aberrant coronary arteries: a reliable echocardiographic screening method.

BACKGROUND: Aberrant origin (ABO) of a coronary artery (CA) from the contralateral aortic sinus with a subsequent interarterial course is a life-threatening condition. It carries a 28% to 55% risk for a sudden coronary event or death, but there are no reliable screening methods. OBJECTIVE: We sought to determine whether imaging a cross section of a coronary segment in the anterior aortic wall on the long-axis view may be used as an echocardiographic screening sign for ABO CA. METHODS: The echocardiograms of all patients with ABO CA were evaluated for the screening sign and compared with those of age-matched control patients. RESULTS: Between January 1989 and October 2002, we identified 8 patients with ABO CA (median age: 15 years). Of these patients, 4 were symptomatic and 4 were discovered incidentally. The electrocardiogram produced normal findings in 5 of 8 patients, maximal stress test produced normal findings in 5 of 6 patients, and thallium perfusion test produced negative results in 2 of 3 patients. There were 4 patients with ABO in the main left CA, 3 with ABO in the right CA, and 1 with ABO in the circumflex CA branch. The screening sign was readily visible in 7 of the 8 patients (88%), and all 7 of these patients had ABO in a main CA. Only in the ABO in the circumflex CA branch was the screening sign not detected. The 1743 control patients (median age: 14 years) showed normal anterior aortic wall, which was void of any CA segment. In 5 control patients (0.3%, P <.001) the normal right CA was visible on the long-axis view, but was not confused for a false-positive screening sign. CONCLUSION: We concluded that the proposed screening sign for ABO CA is reliable and easily recognizable, and should prompt a comprehensive assessment of the CA.