Intra-arterial Readings Research Articles

Comparison of auscultatory and oscillometric automated blood pressure monitors in the setting of preeclampsia

Objective: The aim of this study was to compare the accuracy of 2 automated blood pressure monitors against mercury sphygmomanometry and intra-arterial blood pressure determination in women with preeclampsia. Study Design: The auscultatory and oscillometric monitors were compared with mercury sphygmomanometry according to the British Hypertension Society protocol and criteria of the Association for the Advancement of Medical Instrumentation in a group of 30 women with proteinuric preeclampsia. In addition both monitors were compared with intra-arterial blood pressure measurements in a group of 6 women with severe preeclampsia. The mean (± SD) of the differences was calculated and a paired t test was used to compare values obtained with each monitor with intra-arterial measurements. Results: Compared with mercury sphygmomanometry the auscultatory QuietTrak monitor markedly underestimated systolic and diastolic blood pressure by 13 ± 15 mm Hg. The oscillometric SpaceLabs 90207 monitor also underestimated systolic pressure by 10 ± 10 mm Hg and diastolic pressure by 8 ± 7 mm Hg. According to the British Hypertension Society grading criteria both monitors achieved the lowest grade (D) for recording systolic and diastolic pressure. The 2 monitors also did not meet the accuracy criteria stipulated by the Association for the Advancement of Medical Instrumentation. Compared with intra-arterial readings the SpaceLabs monitor significantly underestimated systolic and mean arterial pressures (by 19 and 7 mm Hg, respectively, P < .01). The QuietTrak monitor significantly underestimated systolic, diastolic, and mean arterial pressures (by 25 mm Hg, P < .05, 18 mm Hg, P < .01, and 20 mm Hg, P < .01, respectively). Conclusion: Neither monitor can be recommended for clinical use in women with proteinuric preeclampsia. (Am J Obstet Gynecol 1999;181:1203-10.)

Pseudohypertension and the Osier Maneuver

To the Editor. —The article from the Cardiovascular Health Study 1 confirms the risks associated with systolic hypertension. The screening methods described, however, do not appear to take into consideration the possibility of pseudohypertension. In this not uncommon entity, the rigid, sclerotic vessels cannot be adequately compressed by the sphygmomanometer cuff, yielding a spuriously elevated blood pressure. 2 The criterion standard of accuracy in a study of hypertension in the elderly would be intra-arterial readings, a method perhaps not regarded as practical in a study of this scope. Infrasonic recorder measurements have also been advocated for accurate, noninvasive screening of diastolic blood pressure. 3 A simpler method of screening is the Osler maneuver, as described by Messerli et al 4 (based on the original observation by Sir William Osler), in which the palpability of the artery distal to the point of occlusion by the cuff indicates the state of the

Pseudohypertension and the Osier Maneuver-Reply

In Reply. —The letter by Dr Golden raises the question of pseudohypertension. Intra-arterial readings are not practicable in large epidemiologic studies. In the design of the Cardiovascular Health Study, we considered but chose not to include Osler's maneuver, in part because the reproducibility or reliability of the measure is so poor. 1 Tsapatsaris and colleagues 1 call it an inadequate test. In our analysis, we excluded subjects with clinical cardiovascular disease, and fewer than 30 were 85 years of age or older. The prevalence of pseudohypertension was therefore likely to be small. The Cardiovascular Health Study methods for measuring blood pressure were the same as those used in many of the major epidemiologic studies and the randomized clinical trials, including the Systolic Hypertension in the Elderly Project. 2 In the Systolic Hypertension in the Elderly Project, the use of diuretics to treat isolated systolic hypertension reduced the incidence of fatal

A comparative study of measurement of arterial blood pressure using HEM-802F and arterial cannulation.

Finger arterial blood pressures determined by a newly developed sphygmomanometer, HEM-802F, were compared with arterial pressure obtained from direct measurement of the radial artery. An excellent correlation was found between the two methods (systolic: r = 0.93, diastolic: r = 0.91), although there was a large variability among individual subjects. The range of differences between them are from +32 to -13 mmHg for systolic and +15 to -25 mmHg for diastolic blood pressure measurement. HEM-802F underestimated systolic pressure (-4.0 mmHg) and overestimated diastolic pressure (+6.7 mmHg), compared with intra-arterial readings. The HEM-802F was useful for the non-invasive arterial pressure monitoring during general anesthesia.

Direct Arterial Blood Pressure Measurements

<h3>To the Editor.—</h3> This is in response to the letter of Elemer K. Zsigmond, MD (1981;245:703), in which he compares direct intra-arterial blood pressure (BP) measurements unfavorably with those obtained by a computerized oscillometric device. Blind reliance on intra-arterial readings can result in serious iatrogenic complications. However, the same can be said about any diagnostic modality. Constant vigilance is always in order. In the operating room, the direct arterial line has distinct advantages: One receives beat-by-beat information rather than historical evidence of the situation a minute or so ago; there are no artifacts such as those produced when an assistant inadvertently leans against the cuff; and last, one can readily obtain samples for arterial blood gas determinations and other laboratory analyses. As to the hazards of arterial cannulation, they are few with careful management and are far outweighed by the advantages cited here.

Arterial pressure and arm circumference.

The relation between sphygmomanometer reading and arm circumference is of more than academic interest. It has obvious implications in the field of population studies in that arm circumference varies with sex, age, weight, and physical demands of occupation, while, at the clinical level, whether or not a man is accepted for life insurance or for an occupation such as crane or lorry driving may turn on an estimate of his arterial pressure made with a sphygmomanometer. Yet evidence about the relation ship remains inconclusive and confusing. Ragan and Bordley (1941) compared, for 51 subjects, the direct measurement of arterial pressure taken in one arm by the intra-arterial method of Hamilton with the indirect measurement of pressure taken simultaneously in the other arm by a standard mercury sphygmomanometer. They found that there was a tendency for indirect readings to be lower than intra-arterial readings for subjects with thin arms and higher for subjects with thick arms. But their data which did not include body weight, were derived from a small, mixed (male and female), and very unrepresentative sample. (Some of the subjects were suffering from hypertension, others had syphilitic aortitis, and their ages ranged from 19 to 60 years). Excluding thirteen subjects with aortic regurgitation or aortitis, Pickering, Roberts, and So wry (1954) used the same data to draw up a Table of Corrections for arm circumference to be applied to sphygmomanometer readings. They admitted that the corrections might be misleading when used on individual readings, but claimed that they were well worth making for the comparison of large groups and then proceeded to apply them to their own data. Others have since followed their example (Miall and Oldham, 1955). More recently, however, Holland and Humerfelt (1964) have failed to demonstrate any relationship between arm circumference and the difference between simultaneously taken direct and indirect measurements of arterial pressure, although they did find a positive correlation between arm circum ference and the direct intra-arterial readings. But their report is incomplete, in view of the fact that it do s not take body weight into account; for arm circumference is highly correlated with weight, and weight itself is known to be related to indirect readings of arterial pressure (Bee, Humerfelt, and W dervang, 1957; Society of Actuaries, 1959). In an analysis of data on physique, occupation, and indirect readings of arterial pressure in a population of more than 5,000 employed men between the ages of 15 and 69 years, Lowe (1964) has confirm d that, for a given age, sphygmomanometer re dings increase with body weight and that weight and arm circumference are highly correlated. When he corrected for weight, he found that the effect of arm circumference upon pressure reading was negligible and he concluded that the greater part, perhaps all, of the observed relationship between rm circumference and sphygmomanometer read ing was attributable to the close association between arm circumference and weight. His con clusion can be criticized, however, on the ground that it is based on the combined readings of twelve different observers, for he had already shown (Lowe and McKeown, 1962) that the observers differed widely in the level at which they recorded systolic and diastolic pressure measurements in comparable populations. In what follows some of the same data are subjected to a more rigorous analysis to meet this objection.