Both body and arm position significantly influence blood pressure measurement

The position of both the body and the arm during indirect blood pressure (BP) measurement is often neglected. The aim of the present study was to test the influence of the position of the patient on BP readings: (1) sitting with the arms supported precisely at the right atrium level and (2) supine: (a) with the arms precisely at the right atrium level and (b) with the arms on the examination bed. In a first group of 57 hypertensive patients, two sessions of BP and heart rate (HR) measurements were performed in two positions: sitting and supine with the arms supported precisely at right atrium level in both positions. BP was measured simultaneously at both arms, with a Hawksley Random Zero sphygmomanometer at the right arm, and with an automated oscillometric device (Bosomat) at the left arm. BP and HR readings obtained in the two positions were then compared. In a second group of 25 normo- and hypertensive persons, two sessions of BP and HR readings were performed in supine with the arms in two different arm positions: (a) the arm placed precisely at right atrium level and (b) the other arm on the examination bed. The measurements were performed at both arms with two automated devices (Bosomat). The readings taken in the two positions were compared. Both systolic BP (SBP; by 9.5 +/- 9.0 (standard deviation, s.d.); right arm) and diastolic BP (DBP; by 4.8 +/- 6.0 mmHg; right arm) were significantly higher in the supine than in the sitting position. When the two different arm positions (body continously supine) were compared in the second part of the study, significantly higher SBP (by 4.6 +/- 6.1 mmHg) and DBP (by 3.9 +/- 2.8 mmHg) were obtained when the arm of the patient was placed on the bed (below the right atrium level), than when the arm was placed at the level of the right atrium. BP readings in sitting and supine positions are not the same. When according to guidelines the arm of the patient is meticulously placed at the right atrium level in both positions, the difference is even greater than when the arm rests on the desk or on the arm support of the chair. Moreover, in the supine position small but significant differences in BP are measured between arm on a 5 cm-high pillow and arm on the bed. In every study reporting BP values, the position of both the body and especially the arm should be precisely mentioned.     

Arm position is important for blood pressure measurement

AIM: To test the effect of positioning the arm on the arm-rest of a common chair, below the officially recommended right atrial level, on the blood pressure (BP) readings in a group of out-patients. PATIENTS AND METHODS: A group of 69 patients (58 hypertensives; 39 males; mean +/- s.d. age 54.1 +/- 16.0 years) participated in the present study. BP and heart rate values obtained in each of the following two positions were compared: (1) sitting with the arms supported on the arm-rests of the chair and (2) sitting with the arms supported at the level of the mid-sternum (the approximation of the right atrial level). BP was measured simultaneously at both arms, with a mercury sphygmomanometer at the right arm and with an automatic oscillometric device at the left arm. RESULTS: Both the systolic and diastolic BPs were significantly higher (P < 0.0001) when the arm was placed on the arm-rest of the chair than at the right atrial level. The same differences +/- s.d. in BP between the two positions were obtained with both measurement techniques: 9.7 +/- 9.4 mm Hg (systolic) and 10.8 +/- 5.8 mm Hg (diastolic) with the mercury sphygmomanometer and respectively 7.3 +/- 8.9 mm Hg and 8.3 +/- 6.0 mm Hg with the oscillometric device. No difference in the heart rate was found between the two positions. CONCLUSIONS: Placing the patient's arms on the arm-rest of the chair instead of at the reference right atrial level, BP measurement will result in spuriously elevated BP values. This may be of great importance for the diagnosis and the subsequent treatment decisions for patients with hypertension.     

Body position and blood pressure measurement in patients with diabetes mellitus

AIMS: World Health Organization (WHO) guidelines recommend that the blood pressure (BP) should be routinely measured in sitting or supine followed by standing position, providing that the arm of the patient is placed at the level of the right atrium in each position. The aim of our study was to test the influence of body and arm position on BP measurement in diabetic patients. METHODS: In 142 patients with diabetes mellitus the BP was measured using a semiautomatic oscillometric device (Bosomat-R): (i) after 5 min of rest sitting on a chair with one arm supported at the right atrial level and with the other arm placed on the arm support of the chair, (ii) after 5 min of rest lying on a bed with both arms placed on a bed, and (iii) after 30 s and after 2 min of standing with one arm (the same as in sitting position) supported at the right atrial level and with the other arm vertical, parallel to the body. RESULTS: Both systolic (SBP) and diastolic (DBP) blood pressures were significantly lower in sitting position with the arm at the right atrial level than in supine position (by 7.4 and 6.6 mmHg, respectively, P < 0.01). In sitting and standing positions, SBP and DBP were higher when the arm was placed either on the arm support of the chair or vertical, parallel to the body, than when the arm was supported at the level of the right atrium (by 6-10 mmHg, P < 0.001). Duration of standing did not influence the estimation of orthostatic hypotension. CONCLUSIONS: The data of this study indicate that the WHO recommendation with regard to the equivalence of sitting and supine BP readings is incorrect at least in diabetic patients, as the sitting BP is lower than the supine BP when the arm was positioned at the right atrial level. In addition, incorrect positioning of the arm in standing position results in an underestimation of prevalence of orthostatic hypotension. We conclude that during BP measurement the arm should be placed at the right atrial level regardless of the body position.     

Influence of different supine body positions on blood pressure: consequences for night blood pressure/dipper-status

OBJECTIVES: To investigate the influence of different supine body positions on blood pressure measured by an ambulatory device. DESIGN AND METHODS: Twenty hypertensive and 20 normotensive subjects of a tertiary hospital outpatient clinic participated. Blood pressure was measured with an ambulatory blood pressure device while lying in the back, left side, right side and abdominal positions. The distance between the antecubital fossa and sternum was measured in all four body positions. An expected blood pressure difference between the arm of measurement and the right atrium (i.e. the midsternum) was calculated for the different body positions. RESULTS: When blood pressure was measured in side position at the left arm in hypertensive subjects, the mean systolic and diastolic blood pressure differences (+/- SD) between the left arm in the lower position and in back position at the same arm were +5/+4 (8/6) mmHg. These differences were -14/-17 (6/4) mmHg for the left arm lying above heart level in side position. Values of the right arm in hypertensives and the measurement at both arms in normotensive subjects yielded similar differences. CONCLUSIONS: Body and arm position can both significantly influence the ambulatory blood pressure and therefore the day-night difference. This comprises one of the main reasons for the moderate individual reproducibility of the blood pressure fall at night.     

The normal range for inter-arm differences in blood pressure

OBJECTIVE: to establish the mean and normal range for the difference in simultaneous systolic and diastolic blood pressure measurements between the right and left arm. SUBJECTS: 462 subjects, age range 20-89 years, in sinus rhythm and with no history of stroke, 98 of whom had a history of cardiovascular disease or were taking vasoactive medication. METHODS: four simultaneous recordings of blood pressure in both arms were made using two automated sphygmomanometers with the subject supine after resting for 10 min. RESULTS: inter-arm systolic and diastolic blood pressure differences show a near normal distribution of values. Some individuals had clinically important differences in systolic and diastolic blood pressure between their arms. The magnitude of these differences was not related to the mean baseline blood pressure. Linear regression analysis did not demonstrate any significant relationship between inter-arm systolic or diastolic blood pressure difference and age in patients of either sex. For systolic blood pressure the mean difference between the right and left arm was 1.1 mmHg and the normal range was -9 mmHg to 11 mmHg. For diastolic blood pressure the mean difference was 0 mmHg and the normal range -10 mmHg to 10 mmHg. CONCLUSION: the frequency of significant inter-arm systolic and diastolic blood pressure differences suggests that the blood pressure should be taken in both arms at the initial consultation. At subsequent visits, the arm in which measurements are taken should be recorded in the case notes. The higher of the two readings should be used to guide further management decisions.     

Assessment of body position to quantify its effect on nocturnal blood pressure under ambulatory conditions

BACKGROUND: Nocturnal blood pressure readings may be influenced by body position because of variation in the vertical distance between heart and cuff level. OBJECTIVES: To quantify the effect of body position on nocturnal blood pressure and to assess whether this effect influences the reproducibility of nocturnal blood pressure. PATIENTS AND METHODS: In 16 individuals (three normotensive and 13 hypertensive) 24 h ambulatory measurement of blood pressure and body position was performed twice, separated by an interval of 2-6 weeks. Body position was measured with five acceleration sensors, which were mounted on the trunk and legs. RESULTS: During the first night, 43 +/- 31% of blood pressure values were measured while participants were in the supine position, 29 +/- 28% when they were lying on their side with the cuffed arm down and 28 +/- 29% when they were lying on their side with the cuffed arm up. During the second night these percentages were 40 +/- 29%, 32 +/- 29% and 28 +/- 25% respectively. Blood pressure readings obtained while individuals were lying with the cuffed arm up were about 10 mmHg lower than those obtained with the individual in either the supine position or lying with the cuffed arm down. After correction for the underestimation attributable to 'cuff-up' readings, nocturnal blood pressure increased by 3 mmHg and the number of non-dippers increased from two to four. Correction did not affect the reproducibility of nocturnal blood pressure measurements (standard deviation of the differences 8.3 mmHg for systolic and 6.0 mmHg for diastolic blood pressure after correction). Dipping status was reproduced in 88% of individuals before correction, and in 87% after correction. CONCLUSIONS: Under ambulatory conditions, a highly variable but sometimes substantial number of blood pressure readings are taken with the cuffed arm above heart level. These readings result in underestimation of nocturnal blood pressure and hence influence dipper-non-dipper classification. However, body position does not seem to have an important influence on the reproducibility of nocturnal blood pressure or dipping status.     

Arm position as a source of error in blood pressure measurement

The present study was designed to assess the value of correct positioning of a patient's arm when measuring blood pressure (BP). A total of 181 subjects were examined, 141 hypertensives on treatment, 25 untreated hypertensives, 15 normotensives. All the subjects underwent three BP measurements after a 5-min resting period in supine position. Then two BP readings were recorded in standing position with the arm either positioned by the patient's side or supported passively at patient's heart level. Average systolic BP (SBP) in standing position were 144.6 +/- 20.2 mmHg with the arm at the side and 136.4 +/- 21.1 mmHg with the arm at the heart level (p less than 0.001); average diastolic pressures were 99.0 +/- 12.0 mmHg and 90.2 +/- 12.3 mmHg (p less than 0.001), respectively. A fall in SBP greater than or equal to 20 mmHg from the supine to the upright position was detected in 18.2% of cases when measurement was performed at heart level; such a reduction was inapparent in two-thirds of cases when the arm was placed at the patient's body side. Incorrect positioning of a patient's arm during BP measurements in standing position leads to overestimation of BP values and masks the presence of postural hypotension.     

Automated device that complies with current guidelines for office blood pressure measurement: design and pilot application study of the Microlife WatchBP Office device

OBJECTIVE: Current guidelines for office blood pressure (BP) measurement recommend mercury devices, both arms measurement in the initial assessment and at least duplicate measurements at follow-up visits. This study presents the design and a pilot application study of an automated device that fulfils American, European, and International guidelines for office BP measurement. DESIGN AND FUNCTIONS: The Microlife WatchBP Office is a professional electronic mercury-free device with three function modes designed for: (a) initial assessment: triplicate automated simultaneous oscillometric both arms measurement at 60-s intervals and when there is a consistent interarm difference more than 20 mmHg systolic and/or more than 10 mmHg diastolic, the arm with the higher BP is indicated. (b) Follow-up assessment: triplicate automated oscillometric single arm measurements at 60-s intervals and their average is displayed. (c) Auscultatory measurement: by an observer using a stethoscope and a digital countdown BP display for patients with arrhythmias and other individuals in whom the oscillometric measurement is not accurate. PILOT APPLICATION STUDY: The 'initial assessment' mode was applied by three physicians in 63 patients (189 readings). Average interarm systolic BP difference was 0.04+/-5.1 mmHg and diastolic 0.4+/-3.2 mmHg. A value more than 10 mmHg interarm difference in nine systolic BP readings (5%) and three (2%) diastolic. No patient had a consistent interarm difference more than 10 mmHg in all three or two of the three readings. CONCLUSION: The Microlife WatchBP Office professional device fulfils current international requirements for office BP measurement and seems to overcome several limitations of this method when applied in clinical practice.     

Effect of standard cuff on blood pressure readings in patients with obese arms. How frequent are arms of a 'large circumference'?

OBJECTIVE: To measure the effect on blood pressure readings when a standard cuff is used on patients with arms of a large circumference, and to determine the frequency of arms of a large circumference. SUBJECTS: Blood pressures were taken in 120 subjects with an arm circumference greater than 33 cm. Also, the arm circumference was determined in 244 patients from a family health unit, and in 216 patients from a hypertension clinic. METHOD: A mercury sphygmomanometer and two different cuff sizes were used in a random sequence; therefore, 60 patients' blood pressure were first measured with a large cuff, followed by a standard cuff; the opposite sequence was then applied for another 60 patients. With the obtained values and using a regression analysis, the difference in blood pressure overestimation was calculated. Arm circumference measurement percentages were used to determine the frequency of arms of a large circumference. RESULTS: Both systolic and diastolic blood pressures were significantly greater when the standard cuff was used. For every 5 cm increase in arm circumference, starting at 35 cm, a 2-5 mmHg increase in systolic blood pressure, and a 1-3 mmHg increase in diastolic blood pressure was observed. The prevalence of arms with a large circumference in the family medicine unit and hypertension clinic was 42% and 41.8%, respectively. CONCLUSIONS: There is an overestimation of blood pressure when a standard cuff is used in obese subjects. The high prevalence of these individuals in our environment, both in the hypertensive and normotensive population, makes it necessary to have on hand different sizes of cuffs for taking blood pressure in order to avoid incorrect decisions.     

Systematic error in the determination of nocturnal blood pressure dipping status by ambulatory blood pressure monitoring

BACKGROUND: Vertical displacement of the arm relative to the heart causes inverse changes in blood pressure of approximately 0.8 mmHg for every centimetre change in arm position. Therefore a potential confounding issue in assessing diurnal variation in blood pressure during ambulatory blood pressure monitoring (ABPM) is arm position during sleep. An increase in the number of patients with 'excessive' nocturnal dipping (> 20% decrease in night/day blood pressure) was observed following the creation of an instructional videotape in which patients were advised to muffle the noise of the monitor with a pillow at night. This raised the possibility that patients were placing their arm on top of the pillow reducing nocturnal blood pressure readings. DESIGN: Ambulatory blood pressure monitoring data from 184 patients prior to and from 193 patients following specific instructions not to put their arm on top of the pillow was examined. RESULTS: Following the instructions, the percentage of patients with 'excessive' nocturnal dipping in blood pressure decreased (excessive systolic dipping 17.4 versus 8.8%, P = 0.014; excessive diastolic dipping 37 versus 24.4%, P = 0.01). Consistent with an increase in the ratio of nocturnal/day pressures, there was an increase in the percentage of patients with inadequate nocturnal dipping (< 10% decrease in night/day blood pressure; systolic dipping 33.7 versus 45.6%, P = 0.02; diastolic dipping 13.0 versus 31.6%, P < 0.001) CONCLUSION: Instructing patients to avoid resting their arm on a pillow at night has a substantial effect on the classification of nocturnal dipping status. Patients need clear instructions not to place their arm on a pillow at night during blood pressure monitoring.     

Clinical evaluation of the QuietTrak blood pressure recorder according to the protocol of the British Hypertension Society

METHODS: The QuietTrak ambulatory blood pressure recorder (Tycos-Welch-Allyn, Arden, North Carolina, USA) was evaluated according to the protocol of the British Hypertension Society (BHS). QuietTrak, a lightweight (355 g), automatic, programmable device, uses an auscultatory measuring system. The protocol of the BHS was composed of subsequent phases with QuietTrak and two observers taking simultaneous measurements on the same arm. RESULTS: No interdevice differences were observed at analysis of variance test either before or after a 1-month period of routine clinical use. The average difference between mercury sphygmomanometer and QuietTrak for systolic and diastolic blood pressures was -0.6+/-3.6 and -0.4+/- 3.6 mmHg before and -0.7+/- 3.3 mmHg and 0.6+/- 3.8 mmHg after the 1-month use. At the main static device validation procedure, performed in 85 subjects, the average difference between observers and QuietTrak was -0.3+/- 3.4 and 0.1+/- 3.5 mmHg for systolic and diastolic blood pressures. Eighty-nine per cent and 99% of systolic and 88% and 98% of diastolic QuietTrak readings were within 5 and 10 mmHg of obsevers, determinations (Class A). In children (n = 33) 87% of systolic and 90% of diastolic QuietTrak readings differed by less than 5 mmHg from the observers' readings (average difference -1.1+/-3.9 and 0.1+/- 3.6 mmHg, respectively). In the elderly (n = 30), 95% and 92% of systolic and diastolic readings were within 5 mmHg of mercury column determinations (average difference -0.8+/-3.2 and -0.2+/-4.5 mmHg). In pregnancy (n = 30), 93% of systolic and 100% of diastolic readings were within 5 mmHg of mercury column determination (average difference -0.3+/-3.4 and 0.1+/- 2.9 mmHg). Device reliability was not affected by posture. Ninety-six per cent and 89% of systolic and diastolic readings differed by less than 5 mmHg from the mercury column determinations in the supine position, 90% and 90% in the standing position, and 88% and 90% in the sitting position. During the treadmill exercise (Bruce protocol), 69% and 88% of systolic and 56% and 83% of diastolic QuietTrak readings differed by less than 5 and 10 mmHg from the observers' measurements. CONCLUSION: The QuietTrak achieved A rating for systolic blood pressure and A rating for diastolic blood pressure according to the criteria of the BHS protocol. The device was acceptable to patients because of its small size, light weight and noiseless performance.     

Reliability of a noninvasive device to measure systemic hemodynamics in hemodialysis patients

OBJECTIVE: To evaluate the reliability of a noninvasive hemodynamic monitor in hemodialysis patients. METHODS: We enrolled 15 male patients (mean age 63+/-12 years) on stable chronic hemodialysis. Blood pressure and hemodynamic readings were obtained with the Dynapulse 500 Guardian device (Pulsemetric Inc., San Diego, California, USA), which measures systemic hemodynamics on the basis of oscillometric waveforms obtained through a cuff placed over the brachial artery. Measurements were taken sequentially, in duplicate, before, during and after hemodialysis, in the supine, seated and standing positions on four separate midweek dialysis sessions over a 2-week period. RESULTS: The repeatability of the method was tested using 200 pairs of valid measurements. The average values (+/-SD) were 137+/-22 mmHg for systolic blood pressure, 80+/-13 mmHg for diastolic blood pressure, 76+/-15 bpm for heart rate, 1320+/-268 mmHg/s for dP/dtmax, 2.8+/-0.5 l/min/m for cardiac index, and 1455+/-359 dyn/s/cm for systemic vascular resistance. The mean differences (+/-SD of the difference) between readings were 0.1+/-10.4 mmHg for systolic blood pressure, 0.3+/-6.0 mmHg for diastolic blood pressure, -0.2+/-8.0 bpm for heart rate, 0.2+/-234 mmHg/s for dP/dtmax, 0.03+/-0.26 l/min/m for cardiac index and -10+/-177 for systemic vascular resistance, yielding limits of agreement (95%) of -20 to 20 mmHg for systolic blood pressure, -11 to 12 mmHg for diastolic blood pressure, -16 to 17 bpm for heart rate, -458 to 458 mmHg/s for dP/dtmax, -0.5 to 0.5 l/min/m for cardiac index and -338 to 357 dyn/s/cm for systemic vascular resistance. Other hemodynamic parameters fared similarly, and coefficients of variation were all between 7 and 18%. CONCLUSION: We conclude that the Dynapulse 500 Guardian has adequate reliability indices in hemodialysis patients.     

The effect of change of position of the arm upon blood pressure

Position of the arm has a definite and uniform effect on blood pressure readings. The systolic pressure is lowest when the arm is hyperabducted, that is, when it is made to lie along the long axis of the body. The systolic pressure becomes higher as the arm is adducted and brought toward the side of the body in the horizontal plane. A neutral position of the arm, 45 to 90 degrees from the side of the body, is probably the optimum position for the estimation of blood pressure. Other positions may cause a marked discrepancy in blood pressure readings.     

Accuracy of the Microlife large-extra large-sized cuff (32-52 cm) coupled to an automatic oscillometric device

To determine the accuracy of the large-extra large-sized (L-XL) cuff (32-52 cm) coupled to a Microlife WatchBP Office ABI blood pressure measuring device tested according to the requirements of the International Protocol of the European Society of Hypertension. The L-XL cuff tested in this study is designed to provide accurate blood pressure measurements in patients with large arms (arm circumference≥32 cm) over a wide range of arm circumferences using a single 145±1×320±1 mm bladder. The evaluation was made in 33 patients with a mean±standard deviation age of 53±17 years (range: 30-96 years). Their systolic blood pressure (SBP) was 142±21 mmHg (range: 110-180 mmHg), diastolic blood pressure (DBP) was 87±14 mmHg (range: 62-106 mmHg) and arm circumference was 36±5 cm (range: 32-50 cm). Blood pressure measurements were made in the sitting position. The L-XL cuff coupled to the WatchBP Office ABI passed all three phases of the European Society of Hypertension protocol for SBP and DBP. Mean blood pressure differences between device and observer were -1.3±5.1 mmHg for SBP and -1.8±5.8 mmHg for DBP. Similar device-observer differences were observed in patients divided into two subgroups according to whether their arm circumference was above or below the median in the group. These results indicate that the L-XL cuff coupled to the WatchBP Office ABI monitor provides accurate blood pressure readings in patients with large arms over a wide range of arm circumferences.     

Inter-arm differences in blood pressure: when are they clinically significant?

OBJECTIVE : To determine whether there is significant disparity in blood pressure between the two arms. DESIGN : Prospective, observational study. SETTING : One general hospital in Birmingham, England. PARTICIPANTS : Four hundred participants [age 56.3 +/- 19.7 years (mean +/- SD), 50% male] were recruited from staff and patients. Simultaneous bilateral blood pressure measurements were obtained using Omron HEM-705CP automated oscillatory devices; with two measurements taken in each arm. MAIN OUTCOME MEASURES : Mean inter-arm blood pressure differences and frequency of clinically important disparities. RESULTS : Mean +/- SD inter-arm differences in systolic and diastolic blood pressure were 1.81 +/- 8.6 mmHg and -0.23 +/- 8.3 mmHg, respectively. The analogous figures for mean +/- SD absolute differences were 6.32 +/- 6.12 mmHg and 5.06 +/- 6.57 mmHg, respectively. Significant differences were present between the mean right and left arm systolic blood pressure [t(399) = 4.20, P < 0.0001], and the mean absolute difference for both systolic [t(399) = 20.65; P < 0.0001] and diastolic [t(399) = 15.39; P < 0.0001] blood pressure. The variation in mean inter-arm blood pressure was unrelated to age, sex, ethnicity, arm circumference, handedness, being hypertensive, diabetic, or previous history of cardiovascular disease. Clinically significant inter-arm differences in systolic blood pressure of > 10 and > 20 mmHg were found in 20 and 3.5%, respectively; diastolic differences of > 10 and > 20 mmHg were present in 11 and 3.5%, respectively. Age was the only significant predictor of clinically significant variations in inter-arm blood pressures and mean absolute blood pressure differences. CONCLUSIONS : Significant differences in mean inter-arm systolic blood pressure, and mean absolute inter-arm systolic and diastolic blood pressure are present. This emphasizes the importance of measuring blood pressure in both arms initially to prevent this misdiagnosis of hypertension, due to normal differences in blood pressure between the arms.     

Comparison of wrist blood pressure measurement with conventional sphygmomanometry at a cardiology outpatient clinic

OBJECTIVE: Oscillometric measurement of blood pressure at the wrist is becoming a widely used method for detection of hypertension and its control by treatment. The objective of the present study was to evaluate accuracy and suitability of wrist measurement in a clinical routine setting. PATIENTS AND METHODS: A series of 333 consecutive patients admitted to our cardiology outpatient clinic were included. Blood pressure was measured at both upper arms according to World Health Organization-International Society of Hypertension guidelines. Oscillometric measurement was performed at the contralateral wrist simultaneously. Blood pressure readings were taken by an oscillometric device applied at the wrist ('Klock'; Industrielle Entwicklung Medizintechnik, Stolberg, Germany) and a conventional mercury sphygmomanometer applied at the upper arm. RESULTS: Seventy-eight patients were excluded due to differences in blood pressure > 5 mmHg between both upper arms or due to 'error' messages of the wrist device. The data of the remaining 255 patients (149 males; mean age, 65 +/- 13 years; range, 18-95 years) are presented. Mean conventional blood pressure was significantly lower compared with the wrist device (137 +/- 20/80 +/- 11 mmHg versus 153 +/- 28/87 +/- 18 mmHg; P < 0.001 and P < 0.001). The mean difference was 16 +/- 25/6 +/- 17 mmHg. In clinical terms, differences in blood pressure exceeding +/-20/+/-10 mmHg reflecting classification of hypertension are considered important. Measurements of 101 (40%) patients were within these limits. Systolic readings of 110 (43%) and diastolic readings of 117 patients (46%) were beyond this scope. CONCLUSION: Due to low reliability of wrist blood pressure measurement, it cannot compete with the upper arm standard procedure. If ever, it should only be used if test readings in an individual comparing wrist and upper arm measurement show differences within a range of +/-20/+/-10 mmHg.     

White-coat effect in normotension and hypertension

OBJECTIVES: The difference between clinic and daytime ambulatory blood pressure is referred to as the white-coat effect. In this study, we investigated (i) the magnitude of the white-coat effect in subjects with different daytime ambulatory blood pressure levels, and (ii) the association of the white-coat effect with left ventricular mass. METHODS: A total of 1581 subjects underwent clinic blood pressure readings, 24-h ambulatory blood pressure monitoring and left ventricular echocardiographic assessment. Their mean daytime systolic blood pressure varied from 88.0 to 208.9 mmHg and their mean daytime diastolic blood pressure from 40.3 to 133.0 mmHg. RESULTS: A negative correlation was found between the systolic or diastolic white-coat effect and the systolic or diastolic daytime ambulatory blood pressure (r = -0.22, P < 0.000 and r = -0.50, P < 0.000, respectively). Left ventricular mass significantly correlated with ambulatory blood pressure (P < 0.001), but there was no association between left ventricular mass and clinic blood pressure or white-coat effect. Furthermore, the white-coat effect was reversed at the highest level of systolic or diastolic daytime ambulatory blood pressure (systolic over 170 mmHg or diastolic over 100 mmHg) when systolic or diastolic daytime ambulatory blood pressure was higher than systolic or diastolic clinic blood pressure (ambulatory blood pressure hypertension). CONCLUSIONS: The white-coat effect shows an inverse association with daytime ambulatory blood pressure level (systolic or diastolic), being significantly more prominent for levels below 140/80 mmHg for systolic/diastolic daytime ambulatory blood pressure and reversed with daytime ambulatory blood pressure levels above 170/100 mmHg.     

Ambulatory blood pressure variations relative to sitting or standing position in renal transplant patients

OBJECTIVE: High blood pressure is almost constant in renal transplant patients for whom dysautonomia is frequently described. The main objective of this study was to analyse the variations in blood pressure and heart rate recorded by ambulatory measurement during changes in position in renal transplant patients. METHODS: Thirty-nine non-diabetic renal transplant patients with a renal transplant functioning for more than a year, were selected at random. Blood pressure was measured using the validated monitor Diasys Integra with a position sensor to discriminate between standing and sitting/lying. RESULTS: Systolic blood pressure and heart rate were significantly higher when the patient was standing than when sitting/lying (+2.9 mmHg, P<0.05 and +9 beats/min, P<0.001 respectively) and diastolic blood pressure tends to be higher (+1.7 mmHg, NS) when standing. One minute after standing up, the heart rate rises by about 9 beats/min (P<0.001) while systolic and diastolic blood pressures do not vary significantly. Variations in systolic blood pressure and heart rate on changing position are therefore in the same direction as those recorded in elderly normotensive or hypertensive untreated subjects, but with a lower amplitude. CONCLUSIONS: In most of non-diabetic functional renal transplant patients, there is an absence of an orthostatic decline in blood pressure. Thus, it could be considered that there is no real dysautonomia in this specific population.     

Validation of the A&D wrist-cuff UB-511 (UB-512) device for self-measurement of blood pressure

OBJECTIVES: To determine the accuracy of the A&D UB-511 (UB-512) oscillometric wrist-cuff device for self-measurement of blood pressure, the only difference between the two devices being the size of storage memory. METHODS: Device evaluation was performed according to the modified British Hypertension Society protocol released in 1993. Eighty-five study participants with characteristics outlined in the British Hypertension Society protocol were recruited among those attending our out-patient clinic. The device was evaluated according to the various steps of the protocol. The non-dominant arm was used for blood pressure measurement. To maintain the wrist at cardiac level during validation, the arm was kept horizontal at the mid-sternum level and supported by a soft table. The wrist was kept extended. Sequential readings were taken for the main validation test. Outcome was classified according to the criteria of the British Hypertension Society recommendations, which are based on four strata of accuracy differing from the mercury standard by 5, 10 and 15 mmHg, or more. RESULTS: The device achieved a British Hypertension Society grade B for systolic and a grade B for diastolic blood pressure. The device tended to overestimate arm blood pressure, the mean difference (+/-1 SD) between device and observers being 4.3+/-8.7 mmHg for systolic blood pressure and 3.7+/-8.1 mmHg for diastolic blood pressure for observer 2, and 4.4+/-8.6 mmHg for systolic blood pressure and 3.8+/-7.9 mmHg for diastolic blood pressure for observer 1. In a logistic regression analysis, age was the sole predictor of an achieved difference between device and mercury column by 5 mmHg or less (hazard ratio 1.020; 95% confidence interval 1.003-1.04; P=0.024). CONCLUSIONS: These data show that the A&D UB-511 (UB-512) device satisfies the British Hypertension Society recommendations with a grade B/B. The device tends to overestimate cuff blood pressure and its accuracy increases with age.     

Arm position and blood pressure: a risk factor for hypertension?

The objective of this study was to re-evaluate the effect of arm position on blood pressure (BP) measurement with auscultatory and oscillometric methods including ambulatory blood pressure monitoring (ABPM). The setting was the hospital outpatient department and the subjects chosen were normotensive and hypertensive. The effect of lowering the arm from heart level on indirect systolic BP (SBP) and diastolic BP (DBP) measurement as well as the importance of supporting the horizontal arm were measured. In the sitting position, lowering the supported horizontal arm to the dependent position increased BP measured by a mercury device from 103+/-10/60+/-7 to 111+/-14/67+/-10 mmHg in normotensive subjects, a mean increase of 8/7 mmHg (P<0.01). In hypertensive subjects, a similar manoeuvre increased BP from 143+/-21/78+/-17 to 166+/-29/88+/-20 mmHg, an increase of 23/10 mmHg (P<0.01). Combined results from normotensive and hypertensive subjects demonstrate a direct and proportional association between BP (SBP and DBP) and the increase produced by arm dependency. Similar changes and associations were noted with oscillometric devices in the clinic situation. However, supporting the horizontal arm did not alter BP. Of particular interest, analysis of 13 hypertensive subjects who underwent ABPM on two occasions, once with the arm in the 'usual' position and once with the arm held horizontally for BP measurement during waking hours, demonstrated changes comparable to the other devices. The mean 12-hour BP was 154+/-19/82+/-10 mmHg during the former period and significantly decreased to 141+/-18/74+/-9 mmHg during the latter period (P<0.01). Regression analysis of the change in SBP and DBP with arm position change again demonstrated a close correlation (r(2)=0.8113 and 0.7273; P<0.001) with the artefact being larger with higher systolic and diastolic pressures. In conclusion, arm movements lead to significant artefacts in BP measurement, which are greater, the higher the systolic or diastolic pressure. These systematic errors occur when using both auscultatory and oscillometric (clinic and ABPM) devices and might lead to an erroneous diagnosis of hypertension and unnecessary medication, particularly in individuals with high normal BP levels. Since clinical interpretations of heart level vary, the horizontal arm position should be the unambiguous standard for all sitting and standing BP auscultatory and oscillometric measurements.