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Effects of mechanical trauma of blood cells on dynamic viscoelasticity of blood during clotting.

Effects of mechanical trauma of platelets and red blood cells on dynamic viscoelasticity of blood during clotting were examined. Two different methods were attempted to give the mechanical damage to blood cells. In one method, a flow apparatus consisting of a thin teflon tube and two sample reservoirs connecting to both ends of the tube was employed. After a blood sample repeated the shuttle flow many times through the tube, the dynamic rigidity modulus (G') and loss modulus (G") of the blood sample during clotting were measured. The mechanical trauma of platelets brought about the increase of G' and G" for clots of PRP and whole blood, in addition to shorter clotting time. Slight hemolysis of red blood cells (less than 0.5% of total hemolysis) only yielded shorter clotting time for whole blood. In other method, packed red blood cells were hemolyzed by exposing the ultrasonic wave (the amount of hemolysis was about 5% of total hemolysis). Addition of supernatant of hemolyzed red blood cells to PRP caused the platelet aggregation. Furthermore, a marked hemolysis brought about higher values of G' and G" for blood clot, in addition to shorter clotting time. These results suggest that the release of constituents from damaged red blood cells and alteration of cell surface due to mechanical damage would accelerate the coagulation sequence.

Blood Coagulation↗

Effect of 24-h blood pressure levels and circadian blood pressure rhythm on left ventricular structure and function in isolated systolic hypertension.

Forty-one participants (mean age 69 +/- 5.6 years) were examined by fully automatic blood pressure monitor and Doppler echocardiography to gain information on the ambulatory blood pressure and the left ventricular structure and function in isolated systolic hypertension. Cumulative sum (cusum)-derived statistics was used to quantify circadian blood pressure rhythm and 24-h blood pressure levels were defined as mean blood pressure values during 24 h, waking (06:00-22:00 h) and sleeping (22:00-06:00 h) periods, respectively. Most of the derivatives of ambulatory blood pressure, including cusum-derived statistics and 24-h blood pressure levels, were significantly related with the left ventricular structural (left ventricular posterior wall and interventricular septum thickness) and functional (acceleration time in the left ventricular outflow tract and early diastolic deceleration time) indexes. Among the left ventricular structural and functional indexes, interventricular septum thickness at end diastole had the strongest correlation with sleeping diastolic mean blood pressure (r = 0.41, P < 0.01), left ventricular posterior wall at end diastole, the best with 24-h systolic mean blood pressure (r = 0.41, P < 0.01), acceleration time the strongest with systolic cusum-derived circadian alteration magnitude (r = 0.49, P < 0.01) and early diastolic deceleration time the greatest with diastolic cusum-derived trough blood pressure (r = 0.45, P < 0.01). We conclude that left ventricular structural changes rely on 24-h systolic and diastolic blood pressure levels, whereas left ventricular functional variations may be more dependent upon circadian blood pressure rhythm in elderly patients with isolated systolic hypertension.

Aged↗

Relationships of glucose concentrations in capillary whole blood, venous whole blood and venous plasma.

We studied the difference in glucose levels between capillary and venous whole blood during 75-g oral glucose tolerance test (OGTT) in 75 healthy subjects. Capillary and venous whole blood glucose values were measured by HK-G6PD method after deproteinization. The post-loaded glucose levels in capillary blood were significantly higher than those in venous blood, and the mean values of capillary and venous difference at 30, 60, 90, 120 and 180 min were 1.37, 1.40, 1.07, 0.95 and 0.52 mmol/l, respectively, with the maximum difference at 60 min. No correlation was found in the magnitude of the differences in glucose between capillary and venous blood specimens. We determined the inaccuracy of six self-monitoring blood glucose devices relative to the reference method using venous plasma, venous whole blood and capillary whole blood from 31 diabetic patients. The differences of mean values of venous whole blood and capillary whole blood, and venous whole blood and venous plasma, and capillary whole blood and venous plasma were 9.6%, 11.3% and -3.2%, respectively. The range of bias and Sy/x were 0.31-1.06 mmol/l and 0.71-1.07 mmol/l, respectively, compared to the reference method using venous plasma.

Blood↗

Improving the safety of the blood supply in Ecuador through external performance evaluation of serological screening of blood donors.

BACKGROUND: The Ecuadorian National Blood System collects approximately 100 000 units of blood per year. Screening for infectious agents is conducted by 23 autonomous blood services using different methodologies and reagents. OBJECTIVES: To evaluate the performance of serology testing by laboratories of the Ecuadorian National Blood Bank System. STUDY DESIGN: Four proficiency panels were distributed between April 2003 and December 2004 containing samples that were characterized as either reactive or non-reactive for hepatitis B surface antigen (HBsAg), antibodies against hepatitis C virus (HCV), and antibodies against human immunodeficiency virus (HIV). Laboratories were classified according to the volume of blood units processed per year, as small (<5000), medium (5000-12000) and large (>12000). RESULTS: Large and medium blood services consistently obtained better results than small ones. All of the 37 anti-HIV antibody false negative results and all of the 20 HBsAg false negative results were reported by small laboratories. False negative results were associated with the use of rapid tests. Laboratories using rapid tests and certain lots of an enzyme-linked immunosorbent assay (ELISA) failed to detect HCV reactive sera in December 2004. CONCLUSION: The high number of incorrect results in most small blood services indicates serious weaknesses in blood screening that require urgent corrective action. The National Blood System has implemented on-site audits, training, technical assistance, and increased oversight. The long-term proposal is to centralize blood testing in two large blood centers. The results presented here underline the importance of strengthening the regulatory framework and oversight in Ecuador and highlight the role of external performance evaluation programs for blood safety improvement.

Blood Banks↗

Blood viscosity, hemodynamics and vascular hindrance in a rat model of acute controlled bleeding and volume restitution with blood or Haemaccel.

BACKGROUND: Hemorrhage and volume restitution with commercially available solutions is followed by reduced blood viscosity. Consequent hemodynamic changes may arise not only from the reduced viscosity itself but also from changes in vascular geometry induced by autoregulation processes. Vascular hindrance reflects the contribution of vascular geometry to flow. Our aim was to explore the possible effects of blood volume restitution with Haemaccel or blood, on regional blood flow and vascular geometry. METHODS: Under ketamine anesthesia, blood was withdrawn at a rate of 0.3 ml/min for 15 min followed by 15 min of stabilization. The shed blood or Haemaccel was infused at the same rate and volume as used for withdrawal. Hemodynamic measurements were performed using radioactive microspheres. Blood viscosity was measured with an Ostwald viscometer. Vascular hindrance was calculated as the resistance/viscosity ratio. RESULTS: Volume replacement with Haemaccel (n=10), compared to blood (n=10), was followed by increased cardiac output and portal venous inflow (37.1 +/- 9.0 and 3.1 +/- 0.5 vs 25.9 +/- 6.8 and 2.2 +/- 0.9 ml x min(-1) x 100 g bw(-1), respectively; P<0.05), decreased viscosity (2.8 +/- 1.3 vs 3.7 +/- 1.3, respectively; P<0.01) and decreased peripheral and splanchnic arteriolar resistance (3.8 +/- 1.1 and 40.9 +/- 7.6 vs 5.2 +/- 1.7 and 61.1 +/- 29.5 mmHg x ml(-1) x min x 100 g bw, respectively; P<0.05). No significant differences between the groups were observed in vascular hindrance and cardiac output distribution. CONCLUSION: Volume replacement with Haemaccel, compared to blood, induced increase in systemic and splanchnic blood flows, reflecting mainly changes in viscosity and not in blood vessel geometry. These results suggest no significant difference in overall activation of autoregulation process between volume restitution with blood or Haemaccel.

Animals↗

Choroidal blood flow and arterial blood pressure.

PURPOSE: Untreated hypertension is associated with ocular complications and is a risk factor for the development and progression of vascular ocular pathologies. We set out to investigate the association between systemic blood pressure and choroidal blood flow. METHODS: All subjects were male non-smokers, who did not receive any medication and had normal or slightly elevated blood pressure (systolic blood pressure < or = 160 mmHg; diastolic blood pressure < or = 100 mmHg). The association between systemic blood pressure and fundus pulsation amplitude, a measure of pulsatile choroidal blood flow, was investigated in 318 volunteers. In addition, the association between systemic blood pressure and blood flow velocities in the posterior ciliary arteries supplying the choroid was investigated in these subjects. RESULTS: Ocular fundus pulsation amplitude (r = 0.252; P < 0.001) and mean flow velocity in the posterior ciliary arteries (r = 0.346, P < 0.001) were significantly associated with mean arterial pressure. The correlation of ocular haemodynamic variables with systolic and diastolic blood pressure was in the same range. CONCLUSIONS: Our data indicate a small, but significant increase in choroidal blood flow with increasing blood pressure.

Adult↗

Benefit and risk perceptions in transfusion medicine: blood and blood substitutes.

Blood transfusion is a remarkably safe, routine procedure in clinical medicine. However, little attention has focused on the perceptions of risk associated with the receipt of blood, blood products or 'blood substitutes'. It is pertinent to ask (i) what key stakeholder groups know about transfusion, (ii) how safe they perceive blood/blood products to be, (iii) how the latter information might influence their own and others' perceptions of risk linked to transfusion, and (iv) the extent to which approved blood substitutes might be preferred over autologous or donor blood. An appreciation of what stakeholders perceive to be the benefits and risks of the receipt of blood and blood substitutes will inform future transfusion strategies. To obtain such information, a programme of research has been initiated at Nottingham. Surveys have targeted key stakeholder groups, namely, UK adult blood donors and nondonors, anaesthetists, general practitioners and health care journalists. Experimental studies examining message framing and cueing have also been conducted with undergraduate students. Such research will improve misunderstandings about current issues associated with blood donation and transfusion against the backdrop of changing public trust of health care professionals and attitudes and expectations on blood safety and benefits of blood substitutes.

Attitude↗

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.

Adult↗

Comparison between casual blood pressure and ambulatory blood pressure monitoring parameters in healthy and hypertensive adolescents.

Casual blood pressure measurements were compared with mean ambulatory blood pressure values during wakefulness and sleep in 45 normotensive and 30 hypertensive adolescents of both sexes aged 10-18 years. Two sets of auscultatory casual blood pressure were obtained, one in a pediatric office setting (office blood pressure), performed by the physician, and one in the ambulatory blood pressure monitoring (ABPM) unit, performed by a trained nurse, prior to the initiation of ABPM (pre-ABPM blood pressure). In normotensive and hypertensive subjects of both sexes, the mean office systolic blood pressure (SBP) was lower than the mean pre-ABPM SBP, and the mean office diastolic blood pressure (DBP) was lower than the mean pre-ABPM DBP. In normotensive participants, the mean pre-ABPM SBP/DBP was lower than the mean ABPM SBP/DBP while awake, the mean ABPM SBP/DBP during sleep being lower than the mean ABPM SBP/DBP values while awake and the mean pre-ABPM SBP/DBP. No statistical difference was demonstrated between the mean office SBP and the mean ABPM SBP during sleep, the mean ABPM DBP during sleep being lower than the mean office DBP. The hypertensive adolescents presented a blood pressure profile similar to that of the normotensive group, albeit shifted upwards, with no significant difference between the mean pre-ABPM SBP and the mean ABPM SBP while awake but a higher mean pre-ABPM DBP than mean ABPM DBP while awake. This study suggests that, by evaluating the casual blood pressure in different environment/observer situations, the power of casual blood pressure to predict inadequate blood pressure control, manifested as abnormal ABPM parameters, can be enhanced. Our data indicate ABPM to be the method of choice for the early diagnosis and adequate follow-up of adolescent hypertension.

Adolescent↗

Increasing hemoglobin oxygen saturation levels in sickle trait donor whole blood prevents hemoglobin S polymerization and allows effective white blood cell reduction by filtration.

UNLABELLED: BACKGROUND Red blood cell (RBC) components from donors with sickle cell trait (Hb AS) often occlude white blood cell (WBC) reduction filters. Techniques were investigated to successfully filter Hb AS donor blood by increasing the Hb oxygen saturation with storage bags and conditions suitable for transfusion products. STUDY DESIGN AND METHODS: Oxygenation kinetics were measured over 3 days in whole-blood units stored in standard-sized 600-mL polyvinylchloride (PVC) bags and whole-blood units divided into three equal parts and stored in standard-sized blood bags made from PVC, tri-2-(ethylhexyl)trimellitate (CLX) plastic, or Teflon. The filterability of Hb AS blood stored for 3 days was tested with whole-blood filters. RESULTS: Oxygen saturation levels did not increase in full whole-blood units from donors without sickle cell trait during 3 days of storage in 600-mL PVC bags. In divided Hb AS whole-blood units stored for 3 days, oxygen saturation levels increased from baseline levels of 45 to 56, 66, and 94 percent after storage in 600-mL PVC, CLX, and Teflon bags, respectively (n = 5, p < 0.02), and all components filtered completely. When full Hb AS whole-blood units from eight donors were stored for 3 days in 1.5-L CLX bags, all units filtered completely, but one had a high residual WBC count. CONCLUSION: Storage of Hb AS whole blood in large-capacity oxygen-permeable bags increases oxygen tension and allows more effective WBC reduction by filtration.

Benzoates↗

Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans.

Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease in mean arterial blood pressure (P less than 0.001) were observed. The duration of this hyperemic phase was 116 min. A highly significant reduction of the subcutaneous vascular resistance (50%) was demonstrated during the hyperemic blood flow rate phase compared with the surrounding phases (P less than 0.0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.

Adult↗

Retinal blood flow in the normal human eye using the canon laser blood flowmeter.

PURPOSE: To establish a retinal blood flow database in normal human eyes using the Canon Laser Blood Flowmeter (CLBF). METHOD: Fourteen healthy subjects (7 males, 7 females) between the ages of 24 and 33 underwent birectional laser Doppler velocimetry (BLDV) in one eye using the CLBF. Measurements consisting of blood vessel diameter (D) in micrometers, velocity (V) in millimeters per second, and flow (F) in microliters per minute were recorded at sites along the major retinal veins. Four to six veins were measured in each eye. Total volumetric blood flow was calculated as the sum of the venous flow rates in the major veins. RESULTS: Total retinal blood flow could be reliably determined on 5 of the subjects (1 male, 4 females). Venous blood vessel diameter ranged from 84 to 177 microm. The correlations between D and F, as well as D and V were found to be significant. Specifically, the correlation coefficient between D and F was 0.885 (p < or = 0.001), while the log-log regression coefficient was 3.35 +/- 0.23 (p < or = 0.001). The correlation coefficient between D and V was 0.694 (p < or = 0.001), while the log-log regression coefficient was 1.43 +/- 0.27 (p < or = 0.001). Total venous blood flow showed a mean of 64.9 +/- (SD) 12.8 microl/min (range: 50.9-80.6 microl/min). Venous blood flow averaged 44.1 +/- 4.5 microl/min temporally and 20.8 +/- 9.2 microl/min nasally, showing a temporal retinal blood flow approximately twice that of the nasal retina (p < 0.001). On the other hand, venous blood flow averaged 30.6 +/- 9.8 microl/min superiorly and 34.3 +/- 8.0 microl/min inferiorly. These values showed no statistical difference. CONCLUSION: The average total retinal blood flow in 5 healthy subjects using the CLBF was 64.9 +/- 12.8 microl/min. Venous blood flow at the temporal retina was about twice that of the nasal retina, whereas flow at the superior and inferior retina showed no statistical difference. Our findings are comparable with studies done using a different BLDV system.

Adult↗

The association between heart rate and blood pressure, blood lipids and other cardiovascular risk factors.

BACKGROUND: Several studies have shown that an elevated heart rate is associated with an increased risk of ischaemic heart disease. The aim of this study was to examine the relationship between heart rate, blood pressure, blood lipids and other cardiovascular risk factors in middle-aged men. METHODS: A total of 7735 men, aged 40-59 years at screening, were selected at random from one of the general practices in each of the 24 towns participating in the cross-sectional (screening) phase of the British Regional Heart Study. Blood pressure and levels of blood lipids (serum total cholesterol, high-density-lipoprotein (HDL) cholesterol and triglycerides) and blood glucose were measured. RESULTS: All men with pre-existing evidence of ischaemic heart disease and those on regular antihypertensive treatment were excluded from the analysis. In the remaining 5597 men, heart rate showed a strong positive correlation with cigarette smoking and body-mass index and decreased significantly at higher levels of physical activity and FEV1 (forced expiratory volume in 1 s). These associations remained significant after adjustment for each other. Age, alcohol intake and social class were not independently associated with heart rate. There was a significant positive association between heart rate and systolic and diastolic blood pressures, levels of blood cholesterol, triglycerides and blood glucose and a significant inverse association between heart rate and HDL-cholesterol levels, even after adjusting for the above confounding factors. After further adjustment for each of the other physiological variables, heart rate remained independently associated with diastolic and systolic blood pressures and levels of triglycerides and blood glucose. The relationship between heart rate and levels of total cholesterol and HDL cholesterol appeared to be secondary to its association with triglyceride levels. The association between body-mass index and heart rate diminished after further adjustments for systolic blood pressure, suggesting that the primary effect of body weight is on blood pressure rather than on heart rate. CONCLUSION: Our findings indicate that elevated heart rate is associated with hypertension and with an atherogenic lipoprotein profile and support the suggestion that disturbance of the autonomic nervous system may underlie these associations.

Adult↗

Blood pressure control assessed by home, ambulatory and conventional blood pressure measurements in the Japanese general population: the Ohasama study.

To assess blood pressure control in the Japanese population, we analyzed previously obtained measurements of conventional, home and ambulatory blood pressures in 1,174 subjects aged > or =40 in a Japanese community. On the basis of conventional blood pressure values and the use of antihypertensive medication, participants were classified as normotensive, untreated hypertensive and treated hypertensive subjects. When 140/90, 135/85 and 135/85 mmHg were used as the hypertension criteria for conventional, home and ambulatory blood pressure measurements, respectively, all three blood pressure values were higher in untreated and treated hypertensive subjects than in normotensive subjects. Among the treated hypertensive subjects, approximately half were classified as hypertensive not only by conventional blood pressure, but also by home or ambulatory measurements. Approximately 10% of the subjects defined as normotensive by conventional blood pressure measurement were classified as hypertensive by home or ambulatory measurements, whereas 60% of the untreated hypertensive subjects as defined by conventional blood pressure measurement had normal home or ambulatory blood pressure values. Therefore, we concluded that 1) the poor blood pressure control in treated hypertensive subjects was attributable not only to the white coat effect but also to inadequate control of blood pressure; and 2) a certain percentage of subjects were misclassified as hypertensive or normotensive by conventional blood pressure measurement.

Adult↗

Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply.

Blood flow to each uterine horn of cows during the oestrous cycle and early pregnancy was determined daily by use of electromagnetic blood flow probes placed around both middle uterine arteries. The pattern of blood flow to uteri of pregnant and non-pregnant cows was similar until Day 14 after mating or oestrus. Between Days 14 and 18 of pregnancy blood flow to the uterine horn containing the conceptus increased (P less than 0.01) 2- to 3-fold, whereas blood flow to the non-gravid uterine horn in these cows remained constant. No corresponding increase in blood flow to the uterine horn ipsilateral to the ovary bearing the CL was observed in non-pregnant cows during this 4-day period. By Day 19 of pregnancy, blood flow to the gravid uterine horn had returned to a level similar to that observed on Day 13. Blood flow to both uterine horns of pregnant cows remained constant from Days 19 to 25 and then increased to the gravid horn (P less than 0.01) markedly until Day 30 whereas blood flow to the non-gravid horn remained low. Uterine blood flow during the oestrous cycle of non-pregnant cows was positively correlated (P less than 0.01) with systemic concentrations of oestradiol and the ratio of oestradiol (pg/ml) to progesterone (ng/ml). There was no association between oestradiol concentrations and blood flow to the gravid uterine horn. These data indicate local control of uterine blood flow by the bovine conceptus which may function to create optimal conditions for the continuation of pregnancy.

Animals↗

Comparison of various blood-typing methods for the feline AB blood group system.

OBJECTIVE: To compare feline blood-typing results determined by use of the card (CARD), gel (GEL), tube (TUBE), University of Pennsylvania (Penn) tube, and Penn slide tests. SAMPLE POPULATION: Blood samples from 38 healthy cats. PROCEDURES: Blood samples, anticoagulated with EDTA, were screened by use of each blood-typing method according to manufacturers' protocols. RESULTS: On the basis of the standard Penn tube and slide test results, 20, 11, and 7 cats were classified as type A positive, type B positive, and type AB positive, respectively. The same results were obtained with the anti-B and anti-B reagents of the TUBE test. Use of anti-A antibodies of original polyclonal and current monoclonal CARD tests resulted in mostly 2+ to 3+ (scale, 0 to 4+) agglutination reactions with blood samples from type A-positive cats; agglutination reactions with blood samples from type AB-positive cats were weak (1+). The anti-B lectin of the CARD test induced a 2+ to 4+ reaction with blood from all type B- and type AB-positive cats. Use of the GEL test allowed recognition of type A and type B blood samples; following addition of anti-A serum to control columns, type B blood was differentiated from type AB blood. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the in-practice CARD test allows identification of type A- and type B-positive cats, but weak reactions of type AB blood with the anti-A monoclonal antibody raise concerns. The modified GEL and TUBE tests appear to be reliable clinical laboratory methods for feline blood typing.

Animals↗

Ambulatory blood pressure: a predictor of left ventricular mass and future blood pressure in subjects predisposed for hypertension.

Twenty-four-hour ambulatory blood pressure (SpaceLab 5200) and a single laboratory blood pressure were measured in a population-derived sample of normotensive men (mean age 36 years) with (n = 13) or without (n = 16) a positive family history of hypertension. The aim was to determine whether ambulatory monitoring was a better predictor than clinical measurements for echocardiographic derived indices of left ventricular mass and for future blood pressure. At the initial examination ambulatory blood pressure could discriminate between the groups, showing significant differences that were not evident from the clinical blood pressure measurement. After 5 years the blood pressure had increased in the group with a family predisposition for hypertension but only one subject had overt hypertension. The correlation between the average day-time blood pressure and the clinical blood pressure at follow-up was only marginally better than the correlation for the initial clinical blood pressure. In contrast to the clinical blood pressure, both day-time and night-time blood pressure averages were significantly correlated to left ventricular mass at the initial examination. It is concluded that in still normotensive subjects, ambulatory monitoring is a better predictor than clinical measurements for left ventricular mass but not for future blood pressure.

Adult↗

[How reproducible is blood pressure measurement? Intra- and interindividual blood pressure variability in routine practice].

Considering the reproducibility of blood pressure readings the epidemiologist and the physician in his clinical work take two different points of view. Studying drug effects the epidemiologist is interested in significant differences of blood pressures in a study population. The physician however, who estimates the effect of his prescription given to an individual patient has to compare single blood pressure readings in single individuals. In a pharmacological study we accept without any doubt the need of certain numbers of investigations to define a difference of 10 mm Hg as significant. In clinical routine however we behave quite differently and judge single readings intuitively as equal or different, independent of any statistical considerations. Not only the doctor but also the scientific societies with the highest reputation share the same point of view. In their recommendations they accept an arithmetic mean of two blood pressure readings as sufficient to judge blood pressures in individuals. In order to discuss this topic primarily from the doctors point, we analysed repeated blood pressure readings of 21 volunteers who tested 20 different blood pressure devices. We conclude, that the ongoing practice of judging the blood pressures of the patients meets only the needs of the epidemiologist. Reproducibility of single readings or mean values of two readings however are insufficient to draw satisfactory conclusions from the distributions of blood pressure in single individuals. Due to the short and long term blood pressure variability increasing the numbers of readings within a single day does not improve reproducibility sufficiently. It seems that the amount of blood pressure readings which are necessary to improve reproducibility of "the patients blood pressures" should be increased and taken over several days. If this is true, daily self-recordings should be the most promising approach.

Adult↗