mmHg For Systolic Pressure Research Articles

The influence of blood volume‐controlled ultrafiltration on hemodynamic stability and quality of life

Dialysis hypotension occurs frequently and is associated with increased morbidity, mortality, and may influence quality of life. We investigated the influence of blood volume (BV)-controlled ultrafiltration on hemodynamic stability and quality of life in a prospective multiple crossover study. Nineteen patients were consecutively treated with standard hemodialysis (HD), BV-controlled ultrafiltration, and again with standard ultrafiltration during 3-week phases, during which different hemodynamic parameters, ultrafiltrate quantities, dry weight, and quality of life were measured. Blood volume-controlled ultrafiltration resulted in increased hemodynamic stability: systolic blood pressure was significantly higher after treatment with BV-controlled HD compared with both standard treatments (p=0.018 and 0.043, respectively). Also, systolic blood pressure reduction, as a measure of blood pressure stability, was significantly smaller during the BV-controlled phase (-3.9 mmHg) compared with both standard phases (-13.7 and -11.0 mmHg): p=0.003 and 0.035, respectively. No difference was found in the occurrence of large decreases of blood pressure (>30 mmHg), decreases below 90 mmHg systolic pressure, or subjective complaints during treatment or after treatment between both treatment modalities. During the course of the study, the dry weight decreased significantly from mean 73.3 to mean 70.9 kg, and the amount of ultrafiltrate was significantly larger using BV-controlled HD compared with standard treatment (mean 2407 vs. mean 2266 mL; p=0.035). Quality of life, measured by visual analog scales (VAS), showed discrete but no consistent differences between study phases. We conclude that BV-controlled HD increases hemodynamic stability and ultrafiltrate amount compared with a standard treatment. No consistent change in quality of life is found between both treatment modalities.

World Hypertension Day 2007

The World Hypertension League is encouraging all of us to focus our attention on hypertension through designation of May 17, 2007, as “World Hypertension Day.”1 Most of the readers of Hypertension will pay more attention to this encouragement than the average person. But, even many of us who focus much of our life on patient care or research related to hypertension need to pause and consider the importance of this often underappreciated risk factor for cardiovascular disease and kidney disease. The recent results of a study of a drug used for treatment of lipid disorders have refocused our thoughts on the importance of hypertension as a risk factor for cardiovascular disease (CVD). Torcetrapib, a potent inhibitor of cholesteryl ester transfer protein that raises high-density lipoprotein cholesterol and lowers low-density lipoprotein cholesterol has been in development for several years. Early studies were quite promising. They demonstrated substantial increases in high-density lipoprotein cholesterol and modest decreases in low-density lipoprotein cholesterol. There was great optimism in the cardiovascular medicine community for this new tool. Early findings of mild increases in both systolic and diastolic blood pressure with the drug were not considered by most to be a major problem, because the increase was only 3 to 4 mm Hg in systolic pressure.2 But in December 2006, a major study of the drug was stopped by the data safety monitoring board because of an increased rate of death from cardiovascular events in patients treated with this drug. Within hours, the company developing the drug stopped all studies with torcetrapib and announced that it would not pursue further efforts for approval of the drug by the US Food and Drug Administration. The US Food …

Cardiovascular Systemic Regulation by Plantar Surface Stimulation

The decreased blood pressure and flow rates associated with orthostasis have been implicated in the etiology of numerous clinical conditions, including deep vein thrombosis, chronic fatigue syndrome, and more recently osteoporosis. Here, we investigate the potential of low-magnitude vibration, applied at the plantar surface, to inhibit the cardiovascular responses of adult women to the orthostatic stress associated with quiet sitting. Thirty healthy women, aged 22-82 years, were exposed to a plantar-based vibration immediately after taking a seated position. Seven stimulus frequencies (0, 15, 22, 44, 60, 90, and 120 Hz, all at 0.2g) were tested on each subject, and cardiovascular responses were followed for 20 minutes. Each subject experienced only a single test frequency on any day. Pre- and poststimulus blood pressures and continuous electrocardiogram results were obtained, from which mean arterial pressure (MAP) and heart rate variability (HRV) were calculated. In the per-protocol study population (n = 25), 20 minutes of quiet sitting was associated with an average depression of 8.95 mm Hg in systolic pressure and of 1.9 mm Hg in diastolic blood pressure, corresponding to an average decrease in MAP of 5.15 mm Hg. These orthostasis-based changes in blood pressure were significantly reduced by exposure to plantar vibration, in a frequency-dependent manner, with essentially complete suppression of the drop in MAP achieved with plantar stimulation at 44 Hz (P < or = . 01). In the orthostatically hypotensive subpopulation (n = 15), both the 9.3-mm Hg depression in MAP and the decline in HRV were eliminated by exposure to plantar vibrations in the 40- to 60-Hz range (P = .01 and P = .03, respectively). These results are consistent with the hypothesis that the plantar vibration may be stimulating type IIA muscle fiber activity in the leg, which is critical for effective skeletal muscle pumping in the absence of locomotion. Our findings lead us to suggest that noninvasive, low-level, plantar-based vibration in the regime of 30-60 Hz can significantly inhibit the effects of the orthostatic stress of quiet sitting on the cardiovascular system.

Assessment of orthostatic hypotension in the emergency room

The study sought to determine the duration of standing needed to detect most cases of orthostatic hypotension (OH) in the emergency room (ER) and to correlate OH with symptoms, hospitalization and survival. Patients attending a tertiary‐center ER within a 2‐month period underwent orthostatic tests after 1, 3 and 5 min of standing. OH was defined as a drop of ⩾20 mmHg in systolic pressure or ⩾10 mmHg in diastolic pressure on assuming an upright posture. Of the 814 patients tested (402 men, mean age 56.6±19.9 years), 206 (25.3%) had OH, detected in most cases (83.5%) after 3 min of standing. OH was associated with significantly higher supine systolic (p = 0.013) and diastolic (p = 0.004) blood pressure, symptoms of syncope (r = 0.11, p<0.001) or dizziness (r = 0.14, p<0.0001) and risk of hospitalization (50.9% vs 22.9%, p<0.0001). Crude mortality was similar between patients with and without OH (13.8% vs 8.7%, p = 0.06). However, on age‐adjusted analysis, patients older than 75 years with OH had significantly increased mortality (p = 0.04). In conclusion, 3 min of standing is apparently sufficient for the diagnosis of most cases of OH. Considering the high rate of OH and its predictive value for hospitalization, it should be routinely assessed in all ER patients.

Effect of Plantar Micromechanical Stimulation on Cardiovascular Responses to Immobility

We investigated the cardiovascular responses of adult women to the influence of extended quiet sitting and the extent to which these responses may be reversed by micromechanical stimulation of the plantar surface. The cardiovascular responses of 20 healthy adult women (mean age, 55.9 +/- 4.45 yrs) were observed during quiet sitting with and without exposure to a plantar-based micromechanical stimulation. Beat-to-beat heart rate via electrocardiogram was acquired along with preexposure and postexposure blood pressures, from which heart rate variability and mean arterial pressure were determined. Seven stimulus frequencies (0, 15, 22, 44, 60, 90, and 120 Hz, all at 0.2 x g, peak to peak) were tested on each subject. Over one-half of the women tested (11/20) exhibited a significant resting tachycardia (mean, 8.3 +/- 0.5 beats/min) with a corresponding decline in their systolic blood pressure (9.45 +/- 1.8 mm Hg) after 20 mins of quiet sitting. Plantar stimulation at 44 Hz (25 mum, peak to peak) was able to completely reverse the effect of immobility in this group, resulting in a heart rate decline of 2.5 beats/min (P < 0.0001) and a decrease of only 1 mm Hg in systolic pressure (P = 0.006). We interpret these results to suggest that the immobility of quiet sitting has a profound effect on the cardiovascular systems in a large fraction of otherwise healthy women, perhaps due to inadequate muscle tone leading to venous insufficiency. Simple external stimulation of the plantar surface seems to be capable of preventing these cardiovascular stress-based responses.

Effects of systematic errors in blood pressure measurements on the diagnosis of hypertension.

To estimate the effects of systematic errors in measurements of blood pressure on the diagnosis of hypertension. We fitted regression curves to distributions of diastolic and systolic BP from recent Canadian and UK surveys and calculated the effect of systematic measurement errors on changes in the numbers of patients who would be classified hypertensive at thresholds of 85, 90 and 95 mmHg diastolic and 140 and 160 mmHg systolic pressure respectively. Overestimation of diastolic BP by 5 mmHg increases the number of patients whose diastolic BP exceeds 85, 90 and 95 mmHg by 102, 132 and 166% respectively. Equivalent underestimation causes 57, 62 and 67% respectively of hypertensive patients to be missed. If systematic error in diastolic pressure is limited to +/-1 mmHg the diagnosis errors are between -15 and +23%. Overestimation of systolic BP by 3 and 5 mmHg increases the number classified as hypertensive by 24 and 43% respectively. Equivalent underestimation causes 19 and 30% of patients with systolic hypertension to be missed. Small systematic errors in BP measurements may cause large variations in the proportion of patients diagnosed as hypertensive. To limit over- or under-diagnosis of diastolic hypertension to approximately 20%, systematic errors in diastolic BP measurements should be limited to 1 mmHg. An uncertainty of 3 mmHg may be adequate for detecting systolic hypertension.

FIRST PROTOTYPE DEVELOPMENT OF AORTIC VALVO-PUMP

Purpose: To develop a prototype of axial flow, micro Aortic Valvo-Pump(AVP) in position of aortic valve in compliance with anatomy and physiology of native heart for long term LVAD. Description of Prototype: Current prototype of AVP is a bearing-less, nonpulsatile pump with dove egg size (24.7 mm in diameter and 12.4 mm in length at its largest point) and total weight of 40 g (rotor 11 g). The rotor has driven magnets and an impeller, and the stator consists of a motor coil and outflow guide vanes. Neither struts nor inflow and outflow tubes are necessary so that minimize the blood flow disturbance and blood resistance across the AVP. The attractive force between rotor magnet and stator coil iron core was minimized to enhance the durability without compromise of motor torque and efficiency. In vitro test: The prototype was tested in a close circuit with a pulsatile centrifugal pump to mimic native heart. Pulsatile pumping flow was generated by constantly rotating AVP, because of pulsatile inflow by mimic native heart. At 15,000 RPM, mean pulsatile pumping flow achieved more than 10 1/min and generate 100 mmHg systolic pressure. During diastole, 15,000 RPM prevents backward flow (zero blood flow cross AVP) from 80 mmHg diastolic pressure. The electricity consumption power is about 7 watts. The endurance test with saline has lasted 4 months (on going) and no mechanical wear can be detected.Figure

Performance of the UA-787 oscillometric blood pressure monitor according to the European Society of Hypertension protocol

To determine the accuracy of the UA-787 oscillometric blood pressure monitor developed by the A&D Company. Evaluation of the UA-787 was performed using the new protocol of the European Society of Hypertension. The performance of the monitor was assessed in relation to the subjects' gender, age, skinfold thickness, arm circumference, body mass index and elasticity index of large (C1) and small (C2) arteries. The UA-787 monitor was assessed according to European Society of Hypertension requirements, which are based on four zones of accuracy differing from the mercury standard by 5, 10, 15 mmHg, or more. In all subjects (n=33), indices of large-artery elasticity (C1) and small-artery elasticity (C2) were measured with the HDI/Pulsewave CR-2000 Research Cardiovascular Profiling System. The UA-787 passed all three phases of the protocol for both systolic and diastolic blood pressure. The mean blood pressure difference between device and the observers was 1.0+/-5.3 mmHg for systolic pressure, and 0.7+/-5.3 mmHg for diastolic pressure. In univariate analysis, the discrepancy between device and the observers was related to forearm circumference (P=0.02) for systolic pressure. For diastolic blood pressure, a significant relationship was found only for heart rate (P<0.01). However, in a multivariable regression analysis no clinical variable was an independent predictor of device-observer discrepancy. In particular, the performance of the UA-787 appeared to be uniform across the whole range of C1 and C2. These data show that the A&D UA-787 device satisfies the new recommended European Society of Hypertension accuracy levels for both systolic and diastolic pressure. Its performance is uniform across sub-groups of subjects with different clinical characteristics.

Assessment of the DIXTAL DX-2710 Automated Oscillometric Device for Blood Pressure Measurement with the Validation Protocols of the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI)

To assess the Dixtal DX2710 automated oscillometric device used for blood pressure measurement according to the protocols of the BHS and the AAMI. Three blood pressure measurements were taken in 94 patients (53 females 15 to 80 years). The measurements were taken randomly by 2 observers trained to measure blood pressure with a mercury column device connected with an automated device. The device was classified according to the protocols of the BHS and AAMI. The mean of blood pressure levels obtained by the observers was 148+/-38/93+/-25 mmHg and that obtained with the device was 148+/-37/89+/-26 mmHg. Considering the differences between the measurements obtained by the observer and those obtained with the automated device according to the criteria of the BHS, the following classification was adopted: "A" for systolic pressure (69% of the differences < 5; 90% < 10; and 97% < 15 mmHg); and "B" for diastolic pressure (63% of the differences < 5; 83% < 10; and 93% < 15 mmHg). The mean and standard deviation of the differences were 0+/-6.27 mmHg for systolic pressure and 3.82+/-6.21 mmHg for diastolic pressure. The Dixtal DX2710 device was approved according to the international recommendations.

Blood pressure and dementia in persons 75+ years old: 3-year follow-up results from the Kungsholmen Project.

A community cohort of 1270 non-demented 75+ years old persons was followed to evaluate the influence of blood pressure on incidence of dementia. Two hundred and eighteen dementia cases were detected during an average of three years of follow-up. Subjects with baseline systolic pressure >/= 180 mm Hg had an age- and gender-adjusted relative risk (RR) of 1.6 (95% to persons with systolic pressure of 141-160 mm Hg. This association persisted, although not statistically significant, when education, vascular diseases, and antihypertensive drug use were entered in the model (RR = 1.4; 95% systolic pressure were not related to dementia incidence. However, individuals with a decrease of 5--19 mm Hg and >/= 20 mm Hg in systolic pressure from baseline to follow-up had a RR of 1.8 (95% 2.6) and 2.5 (95% also found in subjects with diastolic pressure reduction. In conclusion, our findings support an association between high systolic pressure and increased risk of dementia, whereas blood pressure reduction may be secondary to the dementia process itself.

Evaluation of plasma levels of renin-aldosterone and blood pressure in women over 35 years treated with new oral contraceptives

Increases in blood pressure and weight are consequences of increased fluid retention following oral contraceptives administration. Hypertension and weight increase are particularly frequent in women over 35 years of age. The aim of the present study was to evaluate the clinical and hormonal effects of a new extra-low dose oral contraceptive [15 μg ethinyl estradiol (EE) and 60 μg gestodene (GSD)] on the renin-aldosterone system in a group of women aged 35–39 years treated for 3 months compared with a formulation containing the same hormones at a higher dose. Eighteen healthy women, age 35–39 years, were divided into two groups. The first group (10 women) used Arianna®, Schering, 15 μg EE/60 μg GSD (EE15/GSD60); the second group (8 women) used Fedra®, Schering, 20 μg EE/75 μg GSD (EE20/GSD75). Blood samples were obtained before the study and after 3 months of contraceptive use for assay of renin and aldosterone. Blood pressure was also measured on both occasions. No significant changes in plasma renin activity (PRA) or plasma concentrations of aldosterone were observed between the two groups after 3 months of contraceptive use. The mean increase in body weight after 3 months of contraceptive use was 350 ± 100 g for EE20/GSD75 and 300 ± 50 g for EE15/GSD60. There was a mean increase of 4 mm Hg for systolic pressure and 2 mm Hg for diastolic pressure in women on EE20/GSD75 and corresponding increases of 3 and 2 mm Hg in women on EE15/GSD60. The changes were not significant in any case. The results of the present study show that the formulations were well tolerated and provided good control of the menstrual cycle in all 18 women. The contraceptive formulations EE20/GSD75 and EE15/GSD60 have no clinical impact on blood pressure, PRA, or aldosterone in this age group.

Effects of stress and behavioral interventions in hypertension--the effects of smoking and nicotine replacement therapy on blood pressure.

Effects of stress and behavioral interventions in hypertension--the effects of smoking and nicotine replacement therapy on blood pressure.

Oxidative Stress in a Rat Model of Obesity-Induced Hypertension

45 The mechanisms underlying the development of hypertension in obesity are not yet fully understood. We recently reported the development of hypertension in a rat model of diet-induced obesity (Dobrian AD et al Hypertension 2000;35: in press). When Sprague-Dawley rats (n=60) are fed a moderately high fat diet(32kcal% fat) for 10-16 weeks, about half of them develop obesity (obesity-prone (OP) and mild hypertension (153±3.4 mmHg systolic pressure), whereas the other half (obesity-resistant, OR) maintains body weight equivalent to low fat control (C) and are normotensive. We examined the potential role of oxidative stress in the development of hypertension in this model. Lipid peroxides measured as thiobarbituric acid reactive substances (TBARS) are showing a significant increase in the LDL fraction of OP rats (2.8±0.32 nmol MDA/mg protein) compared to OR and C (0.9±0.3 nmol MDA/mg protein). Also, aortic and kidney TBARS showed a significant 3- and 5- fold increase in OP rats after 16 weeks of diet (3.3±0.44 aorta and 6.7±0.52 nmol MDA/mg protein kidney) vs OR. In addition, superoxide generation by aortic rings, measured by lucigenin (25μM) luminescence showed a 2-fold increase in the OP group (4325.6±174 RLU/15 min/mg DNA X10 5 ) compared to both OR and C. Plasma renin activity was 2-fold increased in OP vs both OR and control groups.The urine nitrate/nitrite measured by LDH colorimetric method showed a 1.8-fold decrease in OP rats (2.4±0.17 μmoles) compared to OR. A similar 1.6-fold decrease was found for plasma nitrate/nitrite in OP rats vs OR and C. However, eNOS expression assessed by semiquantitative RT-PCR showed a strong increase in the OP rats vs OR and controls in both kidney cortex(eNOS/β-actin ratio of 0.78±0.21 in OP vs 0.32±0.16 in OR)and medulla(0.86±0.18 in OP vs 0.36±0.14 in OR), suggesting a possible shift toward superoxide vs NO production by the eNOS enzyme.Also, eNOS expression was increased ∼4.8-fold in the thoracic aorta of OP compared to OR rats. Collectively, data show a decreased NO production in OP animals, due in part to the increased oxidative stress, possibly generated by the activation of renin-angiotensin system and increased eNOS expression.

Prepubertal stature and blood pressure in early old age

AIMSTo test the hypothesis that childhood growth rate is a marker for formation of control mechanisms that influence blood pressure in early old age.METHODSData are from a sample of 149...

Prognostic Value of 24-Hour Blood Pressure in Pregnancy

So-called “white coat hypertension” (WCH), elevated blood pressure (BP) in the physician’s office but not outside the medical setting, is a common observation in young, nonobese women. Its prognostic significance, if any, remains unclear. In this prospective study, 24-hour monitoring was performed in 148 clinically hypertensive pregnant women in the third trimester and in 106 normotensive women. The criterion pressure values were 140 mm Hg for systolic pressure and 90 mm Hg for diastolic pressure. WCH was considered present when a woman with office hypertension had an average 24-hour pressure of 125/74 mm Hg or less. Those with higher 24-hour pressures were viewed as having true hypertension. Pressures were recorded noninvasively using a pressurometer; diastolic readings were obtained at Korotkoff phase 5. BP monitoring was generally well tolerated. WCH was diagnosed in 29 percent of women with clinical hypertension. Pregnancy-induced hypertension, a combination of transient late gestational hypertension and preeclampsia, was diagnosed in 19 percent of the WCH group, 13 percent of normotensive women, and 95 percent of those with true hypertension. Preeclampsia was comparably frequent in the WCH and normotensive groups (7 and 6 percent, respectively) but occurred in 62 percent of women with true hypertension. Women with true hypertension had shorter pregnancies than the others. Forty-five to 50 percent of women with WCH or true hypertension had cesarean deliveries, compared with only 12 percent of normotensive women. Birth weights were lower in the true hypertension group, but not when women had only WCH. One month after delivery, three women with WCH again had elevated office BP. Nearly 30 percent of women in this study with high office BP in the third trimester proved to have WCH. Monitoring BP over 24 hours is more informative than relying on office pressures. It may be that an appreciable number of women thought to have transient gestational hypertension actually have WCH. J Am Med Assoc 1999;282:1447–1452

Significant Role of the Increase in Renin-Angiotensin System in Cardiac Hypertrophy and Renal Glomerular Sclerosis in Double Transgenic Tsukuba Hypertensive Mice Carrying Both Human Renin and Angiotensinogen Genes

Tsukuba hypertensive mice (THM) are a hypertensive model prepared by mating a transgenic mice with human renin gene and a transgenic mice with human angiotensinogen gene. In the present study, we examined effects of renin-angiotensin system (RAS) on cardiac hypertrophy and renal disorders using Tsukuba hypertensive mice. While THM showed an increase of about 30 mmHg in systolic pressure compared to C57BL/6 mice employed as normal control animals, the increase in blood pressure was not observed in the mice to which either gene was transferred. Urinary volume, water intake volume, urinary albumin excretion, heart to body weight ratio and renal glomerular sclerosis index increased significantly in THM, but none of these parameters showed a significant difference from the C57 mice when they were examined in mice to which either of the genes was transferred. In contrast, when lisinopril was administered to THM, all the parameters decreased significantly without lowering the systolic pressure. From these findings, it was demonstrated that RAS was playing a significant role in cardiac hypertrophy and renal disorders of THM and that lisinopril had inhibitory effects on cardiac hypertrophy and renal glomedar sclerosis by inhibiting RAS

Comparison of an Auscultatory Versus an Oscillometric Ambulatory Blood Pressure Monitor in Normotensive, Hypertensive, and Preeclamptic Pregnancy

Objective: To compare the accuracy of the auscultatory Profilomat ambulatory blood pressure monitor and the oscillometric SpaceLabs 90207 in pregnant women.Methods: Evaluation of study devices was performed according to the device validation protocol of the British Hypertension Society. Both study devices were compared with standard mercury sphygmomanometry in one single group of 55 pregnant women, of whom 21 were normotensive, 22 had mild hypertension, and 12 mild preeclampsia.Results: The mean differences (SD) between observers and SpaceLabs 90207 were -3(6) mmHg for systolic pressure, 13(7) mmHg for Korotkoff phase 4 diastolic pressure and 4(7) mmHg for Korotkoff phase 5 diastolic pressure. The mean differences (SD) between observers and Profilomat were 3(4) mmHg for systolic pressure, 10(6) mmHg for phase 4 diastolic pressure, and 4(7) mmHg for phase 5 diastolic pressure. Both devices achieved BHS grades B, D, and C for systolic, phase 4 diastolic, and phase 5 diastolic pressures, respectively. However, 95% limits of agreement between observers and study device were wide for both SpaceLabs 90207 and Profilomat. Phase 5 diastolic pressure differences between observers and both study devices were significantly greater in hypertensive women compared to normotensive women.Conclusions: The auscultatory Profilomat monitor is as accurate as the oscillometric SpaceLabs 90207 in normotensive pregnant women, and in pregnant women with mild hypertension or mild preeclampsia. Our results do not allow conclusions on accuracy in women with severe hypertension or severe preeclampsia. For both devices, differences from mercury sphygmomanometry can be large in individual pregnant women, and increase with level of blood pressure.

The relationship between the intrauterine environment and blood pressure in 3-year-old Japanese children.

In 195 Japanese children the systolic pressure at 3 years of age was inversely correlated to the body weight at birth and positively correlated to the mothers' systolic pressure during pregnancy: the average systolic pressure in children whose body weight at birth exceeded 3510 g was 3.0 mmHg, which was lower than that of children whose body weight at birth was 2990 g or less. There was an increase of 0.12 mmHg in the children's systolic pressure with each increment of 1 mmHg in the systolic pressure of their mothers. The systolic pressure at 3 years in children of mothers who had had pretibial oedema during pregnancy (101.0 +/- 8.8 mmHg) was significantly higher compared with children whose mothers did not have oedema (96.6 +/- 9.6 mmHg).

Factors contributing to hypotension during hemodialysis

Background The characteristics of patients receiving chronic hemodialysis in the United States has continuously changed over the past three decades. Today the patients are older, and the incidence of diabetic nephropathy has markedly increased. Hypotension during hemodialysis is the most common and bothersome complication of chronic hemodialysis. The demographics of those patients who experience hypotension during dialysis has not been previously identified. Methods The change in systolic pressure during hemodialysis was reviewed for ten consecutive hemodialysis treatments in 134 patients in a single hospital-based unit. For the past four years, those patients who have had symptoms during their hypotensive episodes associated with hemodialysis have been under continuous therapy with midodrine. Results In the present study, the overall incidence of patients experiencing decreases of, at least, 40 mmHg systolic pressure, in over 50% of their treatments, is 63%. The incidence of patients having symptoms from hypotension during hemodialysis is 25%. Analysis of the dialysis population shows that the age of the patients is a primary factor leading to hypotension. Diabetic nephropathy is identified as a second risk factor for hypotension. However, the incidence in the asymptomatic group versus the symptomatic group was not statistically significant. In the group of patients (25%) who have hypotension during hemodialysis with clinical symptoms, all had hypertension requiring therapy prior to initiating hemodialysis. Hypertension may be a predisposing factor to the development of hypotension. Females tended to have more hypotension during dialysis than males. Conclusions As a result of the increasing age of patients receiving hemodialysis and the increasing incidence of diabetic nephropathy, hypotension will become an even greater problem in the future.

Noninvasive blood pressure monitoring from the supraorbital artery using an artificial neural network oscillometric algorithm.

Our objective was to overcome the limitations of linear models of oscillometric blood pressure determination by using a nonlinear technique to model the relationship between the oscillometric envelope and systolic and diastolic blood pressures, and then to use that technique for near-continuous arterial pressure monitoring at the supraorbital artery. An adhesive pressure pad and transducer were used to collect oscillometric data from the supraorbital artery of 85 subjects. These data were then used to train an artificial neural network (ANN) to report diastolic or systolic pressure. Arterial pressure measurements defined by brachial artery auscultation were used as a reference. ANN results were compared with those obtained using a standard oscillometric algorithm that determined pressures based on fixed percentages of the maximum oscillometric amplitude. The ANN produced better estimates of reference blood pressures than the standard oscillometric algorithm. Mean difference between target and actual output for the ANN was 0.50 +/- 5.73 mm Hg for systolic pressures, compared to the mean difference of the standard algorithm of 2.78 +/- 19.38 mm Hg. For diastolic pressures, the ANN had a mean difference of 0.04 +/- 4.70 mm Hg, while the mean difference of the standard algorithm was -0.34 +/- 9.75 mm Hg. The ANN produced a better model of the relationship between the oscillometric envelope and reference systolic and diastolic pressures than did the standard oscillometric algorithm. Noninvasive blood pressure measured from the supraorbital artery agreed with pressure measured by auscultation in the brachial artery, and may sometimes be more clinically useful than an arm cuff device.