Ambulatory blood pressure monitoring in the elderly

The incidence of hypertension is high in the elderly and is present in 2/3 of the patients older than 65 years. Prevalence can reach 90% in patients older than 80 years. The presence of isolated systolic hypertension (ISH) is characteristic of this population. However, the prevalence of hypertension by ambulatory blood pressure monitoring (ABPM) is not well known. In this study, we analyzed the special characteristics of hypertension in this population, giving special emphasis on ABPM readings

Accuracy profile validation of a new method for carbon monoxide measurement in the human blood using headspace-gas chromatography-mass spectrometry (HS-GC-MS).

The aim of our study was to provide an innovative headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable for the routine determination of blood CO concentration in forensic toxicology laboratories. The main drawback of the GC/MS methods discussed in literature for CO measurement is the absence of a specific CO internal standard necessary for performing quantification. Even if stable isotope of CO is commercially available in the gaseous state, it is essential to develop a safer method to limit the manipulation of gaseous CO and to precisely control the injected amount of CO for spiking and calibration. To avoid the manipulation of a stable isotope-labeled gas, we have chosen to generate in a vial in situ, an internal labeled standard gas ((13)CO) formed by the reaction of labeled formic acid formic acid (H(13)COOH) with sulfuric acid. As sulfuric acid can also be employed to liberate the CO reagent from whole blood, the procedure allows for the liberation of CO simultaneously with the generation of (13)CO. This method allows for precise measurement of blood CO concentrations from a small amount of blood (10 μL). Finally, this method was applied to measure the CO concentration of intoxicated human blood samples from autopsies.

Prevalence and genotyping of hepatitis C virus in blood donors in the state of Pará, Northern Brazil

Given the scarcity of epidemiological information on hepatitis C virus (HCV) infection in Northern Brazil, we determined the prevalence and genotypic frequency in blood donors in the state of Pará (PA). Blood samples from all of the blood donors at the Fundação HEMOPA (blood bank of PA) from 2004-2006 were screened for the presence of antibodies to anti-HCV and samples seroreactive to anti-HCV were further tested for HCV RNA using real-time PCR. In total, 116 HCV-RNA samples were genotyped, based on maximum likelihood phylogenetic analyses, using BioEdit, Modelgenerator, PHYML and FigTree software. The population consisted of 242,726 volunteers who donated blood from 2004-2006; the most common subgroup was males between the ages of 18-29 years old (37.30%). Within the whole group, 1,112 blood donors (0.46%) had indeterminate or positive serology; among these, 28.78% were males whose ages ranged from 18-29 years. A diagnosis of chronic HCV infection was confirmed for 304 donors (60.20% males; 66.45% were 30-49 years old), resulting in a prevalence of HCV RNA in 0.13% of the samples (304 of 242,726). HCV genotyping revealed a high frequency of genotype 1 (108/116) followed by genotype 3 (8/116). This study found HCV infection to be relatively infrequent in PA; genotype 1 was most commonly isolated. This information can help guide prevention and control policies aimed at efficient diagnosis and control measures.

Evaluation of buffy coat 16S rRNA PCR, buffy coat culture and whole blood PCR for detection of bacteraemia

The use of Gram type-specific PCR on buffy coat from clinical specimens for the detection of bacteraemia was evaluated for the first time using whole blood culture as the gold standard. In addition, the established buffy coat culture and whole blood PCR were also compared. Gram-positive bacteria belonging to six species and Gram-negative bacteria from 10 species were isolated and identified by culture and detected using broad-range 16S rDNA primers and Gram-specific primers. Data from the three methods all conferred very high sensitivity, specificity, positive and negative predictive values when compared to whole blood culture. The Kappa coefficients of agreement were 0.9819 (buffy coat PCR), 0.9458 (whole blood PCR) and 1.0 (buffy coat culture), which establishes their validity as alternative methods to routine blood culture in detecting bacteraemia. In addition, results showed that there was a direct correlation of WBC counts greater than 12,000 cells per mm³ to the occurrence of bacteraemia as detected by the four methods (p < 0.05).

The return of increased blood pressure after discontinuation of antihypertensive treatment is associated with an impaired post-ischemic skin blood flow response.

OBJECTIVE: To assess the post-ischemic skin blood flow response after withdrawal of antihypertensive therapy in hypertensive patients with normal blood pressure during treatment. DESIGN AND METHODS: Twenty hypertensive patients (group A) with a normal clinic blood pressure (<140/ 90 mmHg) receiving antihypertensive treatment (any monotherapy; one pill per day for at least 6 months) had their treatment discontinued. Before medication withdrawal and 2, 4, 12 and 24 weeks thereafter, the following measurements were made: clinic blood pressure, home blood pressure (three times per week, morning and evening) and skin blood flow response to a 5 min forearm arterial occlusion (using laser Doppler flowmetry). The patients were asked to perform an ambulatory blood pressure recording at any time if home blood pressure was > or =160/95 mmHg on two consecutive days, and treatment was initiated again, after determination of the skin hyperemic response, if daytime ambulatory blood pressure was > or =140/90 mmHg. The same studies were performed in 20 additional hypertensive individuals in whom antihypertensive treatment was not withdrawn (group B). The allocation of patients to groups A and B was random. RESULTS: The data fom 18 patients in group A who adhered strictly to the procedure were available for analysis. Seven of them had to start treatment again within the first 4 weeks of follow-up; four additional patients started treatment again during the next 8 weeks (group A1). The seven other patients remained untreated (group A2). The skin hyperemic response decreased significantly in patients in group A1 and returned to baseline values at the end of the study, when there were again receiving antihypertensive treatment. In patients in group A2 a significant attenuation of the hyperemic response was also observed. This impaired response was present even at the end of the 6 month follow-up, at which time the patients were still untreated but exhibited a significantly greater blood pressure than before drug discontinuation. The hyperemic response of patients who did not stop treatment (group B) did not change during the course of the study. CONCLUSIONS: Our findings show a decrease in the postischemic skin blood flow response after withdrawal of antihypertensive treatment in hypertensive patients. This impaired response may be due to the development of endothelial dysfunction, vascular remodeling, or both, and might contribute to the return of blood pressure to hypertensive values after withdrawal of antihypertensive therapy.

Polymerase chain reaction of peripheral blood as a tool for the diagnosis of visceral leishmaniasis in children

The diagnosis of visceral leishmaniasis (VL) generally requires the use of invasive tests for the collection of infected tissue (aspirates of bone marrow, spleen, liver or lymph nodes). This difficulty has led to the search for safer and less painful techniques to confirm the occurrence of the disease in children. Polymerase chain reaction (PCR) is a method that is advantageous in that it allows the use of peripheral blood samples for diagnosis. This paper reports the utilisation of PCR on peripheral blood samples to diagnose VL in 45 children in Mato Grosso do Sul, Brazil. This technique is compared with methods carried out using tissue collected by invasive procedures, including direct microscopy, culture and detection of Leishmania DNA by PCR in bone marrow aspirates. The results show that PCR of peripheral blood provides great sensitivity (95.6%) that is similar to that from the PCR of bone marrow aspirates (91.1%) and higher than that achieved with microscopy (80%) or culture (26.7%) methods. PCR of peripheral blood proved to be a suitable tool for the diagnosis of VL in children because it is highly sensitive and safe, with tissue collection being less invasive than in traditional tests.

Body mass index, abdominal adiposity and blood pressure: consistency of their association across developing and developed countries.

BACKGROUND: Obesity is increasing worldwide because developing countries are adopting Western high-fat foods and sedentary lifestyles. In parallel, in many of them, hypertension is rising more rapidly, particularly with age, than in Western countries. OBJECTIVE: To assess the relationship between adiposity and blood pressure (BP) in a developing country with high average BP (The Seychelles, Indian Ocean, population mainly of African origin) in comparison to a developed country with low average BP (Switzerland, population mainly of Caucasian origin). DESIGN: Cross-sectional health examination surveys based on population random samples. SETTING: The main Seychelles island (Mahé) and two Swiss regions (Vaud-Fribourg and Ticino). SUBJECTS: Three thousand one hundred and sixteen adults (age range 35-64) untreated for hypertension. MEASUREMENTS: Body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), systolic and diastolic blood pressure (SBP and DBP, mean of two measures). METHODS: Scatterplot smoothing techniques and gender-specific linear regression models. RESULTS: On average, SBP and DBP were found to increase linearly over the whole variation range of BMI, WHR and WC. A modest, but statistically significant linear association was found between each indicator of adiposity and BP levels in separate regression models controlling for age. The regression coefficients were not significantly different between the Seychelles and the two Swiss regions, but were generally higher in women than in men. For the latter, a gain of 1.7 kg/m(2) in BMI, of 4.5 cm in WC or of 3.4% in WHR corresponded to an elevation of 1 mmHg in SBP. For women, corresponding figures were 1.25 kg/m(2), 2.5 cm and 1.8% respectively. Regression coefficients for age reflected a higher effect of this variable on both SBP and DBP in the Seychelles than in Switzerland. CONCLUSION: These findings suggest a stable linear relation of adiposity with BP, independent of age and body fat distribution, across developed and developing countries. The more rapid increase of BP with age observed in the latter countries are likely to reflect higher genetic susceptibility and/or higher cumulative exposure to another risk factor than adiposity.

Reactive rise in blood pressure upon cuff inflation : cuff inflation at the arm causes a greater rise in pressure than at the wrist in hypertensive patients

Résumé en français: Il est admis que l'inflation d'une manchette à pression au niveau du bras engendre une augmentation réactionnelle de la tension artérielle qui peut être le résultat d'une gêne lors de l'inflation et peut diminuer la précision de la mesure. Dans cette étude, nous comparons séquentiellement l'augmentation de la tension artérielle lorsque la manchette à pression est positionnée au niveau du bras et au niveau du poignet. Nous avons étudié un collectif de 34 participants normotendus et 34 patients hypertendus. Chacun d'eux était équipé de deux manchettes à pression, l'une au niveau du bras et l'autre au niveau du poignet. Nous avons randomisé l'ordre d'inflation des manchettes ainsi que la pression d'inflation maximale (180mmHg versus 240mmHg). Trois mesures étaient effectuées pour chaque pression d'inflation maximale, ceci au bras comme poignet, et leur séquence était également randomisée. En parallèle, un enregistrement continu de la tension artérielle avait lieu au niveau du majeur de la main opposée à l'aide d'un photoplethysmographe. Cette valeur était considérée comme la valeur de tension artérielle au repos. Pour les participants normotendus, aucune différence statistiquement significative n'a pu être mise en évidence en lien avec la position de la manchette à pression, ceci indépendamment de la pression d'inflation maximale. Variation de la pression systolique à 180 mmHg: 4.3+/-3.0 mmHg au bras et 3.7+/-2.9 mmHg au poignet (p=ns), à 240 mmHg: 5.5+/-3.9 au bras et 4.2+/-2.7 mmHg au poignet (p=0.052). En revanche, concernant les patients hypertendus, une augmentation significative de la tension artérielle a été mise en évidence entre le bras et le poignet. Ceci pour les valeurs de tension artérielle systolique et diastolique et quelle que soit la pression d'inflation maximale utilisée. Augmentation de la pression artérielle systolique 6.513.5 mmHg au bras et 3.812.1mmHg au poignet pour une pression d'inflation maximale de 180 mmHg (p<0.01) et respectivement 6.413.5 mmHg et 4.713.0 mmHg pour 240 mmHg (p=0.01). L'augmentation des valeurs de tension artérielle était indépendante de la valeur tensionnelle de base. Ces résultats montrent que les patients hypertendus réagissent significativement moins à l'inflation d'une manchette ä pression lorsque celle-ci est positionnée au niveau du poignet par rapport au bras, ceci indépendamment des valeurs de tension artérielle de base des patients. Nous pouvons donc suggérer que l'inflation d'une manchette à pression cause moins de désagrément lorsqu'elle est placée au niveau du poignet, notamment chez les patients hypertendus et qu'elle peut être une alternative à la mesure standard au niveau du bras.

Surgical menopause increases salt sensitivity of blood pressure

Salt sensitivity of blood pressure is associated with an elevated risk of developing hypertension (HTN) and is an independent risk factor for cardiovascular disease. The prevalence of HTN increases after menopause. The aim of this study was to investigate prospectively whether the loss of ovarian hormones increases the occurrence of salt sensitivity among healthy premenopausal women. We enrolled 40 normotensive, nondiabetic women (age 47.2+/-3.5), undergoing hysterectomy-oophorectomy for nonneoplastic processes and not on hormone replacement, to determine the effect of changes in sodium intake on blood pressure the day before and subsequently 4 months after surgical menopause. Salt loading was achieved using a 2-L normal saline infusion and salt depletion produced by 40 mg of intravenous furosemide. A decrease >10 mm Hg in systolic blood pressure between salt loading and salt depletion was used to define salt sensitivity. Before and after menopause, salt-sensitive women exhibited higher waist/hip and waist/thigh ratios (P<0.01). Although all of the women remained normotensive, the prevalence of salt sensitivity was significantly higher after surgical menopause (21 women; 52.5%) than before (9 women; 22.5%; P=0.01), because 12 (38.7%) salt-resistant women developed salt sensitivity after menopause. In summary, we demonstrated that the prevalence of salt sensitivity doubled as early as 4 months after surgical menopause, without an associated increase in blood pressure. Epidemiological studies indicate that development of HTN may not occur until 5 to 10 years after menopause. The loss of ovarian hormones may unmask a population of women prone to salt sensitivity who, with aging, would be at higher risk for the subsequent development of HTN and cardiovascular disease.

Socioepidemiological screening of serologically ineligible blood donors due to Chagas disease for the definition of inconclusive cases

Epidemiological screening combined with serological tests has become an important tool at blood banks for the characterization of donors with or without Trypanosoma cruzi infection. Thus, the objective of the present study was to describe the sociodemographic and epidemiological characteristics of blood donors with non-negative serology for T. cruzito determine possible risk factors associated with serological ineligibility. Sociodemographic and epidemiological data were collected by analysis of patient histories and interviews. The data were analyzed descriptively using absolute and relative frequencies and odds ratio (OR) evaluation. The frequency of serological ineligibility was 0.28%, with a predominance of inconclusive reactions (52%) and seropositivity among first-time donors (OR = 607), donors older than 30 years (OR = 3.7), females (OR = 1.9), donors from risk areas (OR = 4) and subjects living in rural areas (OR = 1.7). The risk of seropositivity was higher among donors who had contact with the triatomine vector (OR = 11.7) and those with a family history of Chagas disease (OR = 4.8). The results demonstrate the value of detailed clinical-epidemiological screening as an auxiliary tool for serological definition that, together with more specific and more sensitive laboratory methods, will guarantee a higher efficacy in the selection of donors at blood centres.

Total hemoglobin mass--a new parameter to detect blood doping?

PURPOSE: All kinds of blood manipulations aim to increase the total hemoglobin mass (tHb-mass). To establish tHb-mass as an effective screening parameter for detecting blood doping, the knowledge of its normal variation over time is necessary. The aim of the present study, therefore, was to determine the intraindividual variance of tHb-mass in elite athletes during a training year emphasizing off, training, and race seasons at sea level. METHODS: tHb-mass and hemoglobin concentration ([Hb]) were determined in 24 endurance athletes five times during a year and were compared with a control group (n = 6). An analysis of covariance was used to test the effects of training phases, age, gender, competition level, body mass, and training volume. Three error models, based on 1) a total percentage error of measurement, 2) the combination of a typical percentage error (TE) of analytical origin with an absolute SD of biological origin, and 3) between-subject and within-subject variance components as obtained by an analysis of variance, were tested. RESULTS: In addition to the expected influence of performance status, the main results were that the effects of training volume (P = 0.20) and training phases (P = 0.81) on tHb-mass were not significant. We found that within-subject variations mainly have an analytical origin (TE approximately 1.4%) and a very small SD (7.5 g) of biological origin. CONCLUSION: tHb-mass shows very low individual oscillations during a training year (<6%), and these oscillations are below the expected changes in tHb-mass due to Herythropoetin (EPO) application or blood infusion (approximately 10%). The high stability of tHb-mass over a period of 1 year suggests that it should be included in an athlete's biological passport and analyzed by recently developed probabilistic inference techniques that define subject-based reference ranges.