The impact of observer and patient factors on the occurrence of digit preference for zero in blood pressure measurement in a hypertension specialty clinic: evidence for the need of continued observation.

BACKGROUND: Many investigators have reported unconscious over-reporting of the terminal digit zero but little literature exists on observer or patient-related factors that may predict the occurrence. This study analyzes the occurrence of zero preference in 52,827 blood pressure (BP) measurements in 8513 patients by 11 hypertension nurse specialists in the Hypertension Division at Mayo Clinic, Rochester, Minnesota. METHODS: Data from the electronic database of the Hypertension Division from April 1997 to September 2001 were analyzed for the occurrence of zero preference. Nurse-specific zero preference was stratified on four variables: number of BPs performed, years as hypertension nurse specialist, time of day BP performed (fatigue), and nursing degree. Three patient-specific factors were analyzed: age at visit (stratified by decade), type of care (continuing versus short-term), and hypertension status. RESULTS: We found significantly increased frequency of zero preference for all BPs with mean frequency of 31% v 20% expected (P < .0001). Individual nurse zero preference varied widely, 22.0% to 53.6% for systolic BP and 22.2% to 40.8% for diastolic BP). Continuing care patients had a higher zero preference than did short-term care patients for both systolic BP (34.5% v 30.2%; P < .0001) and diastolic BP (34.7% v 33.3%; P = .006). Zero preference was also more common at higher categories of hypertension (P < .001). Time of day, nursing degree, patient age, the number of BPs performed, years of service did not affect the occurrence of digit preference. CONCLUSIONS: Digit preference was demonstrated and varied significantly among well-trained hypertension nurse specialists. Further studies in a larger number of observers are required.

Patent foramen ovale: innocent or guilty? Evidence from a prospective population-based study.

OBJECTIVES: We sought to determine the association between patent foramen ovale (PFO), atrial septal aneurysm (ASA), and stroke prospectively in a unselected population sample. BACKGROUND: The disputed relationship between PFO and stroke reflects methodologic weaknesses in studies using invalid controls, unblinded transesophageal echocardiography examinations, and data that are unadjusted for age or comorbidity. METHODS: The use of transesophageal echocardiography to identify PFO was performed by a single echocardiographer using standardized definitions in 585 randomly sampled, Olmsted County (Minnesota) subjects age 45 years or older participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. RESULTS: A PFO was identified in 140 (24.3%) subjects and ASA in 11 (1.9%) subjects. Of the 140 subjects with PFO, 6 (4.3%) had an ASA; of the 437 subjects without PFO, 5 had an ASA (1.1%, two-sided Fisher exact test, p = 0.028). During a median follow-up of 5.1 years, cerebrovascular events (cerebrovascular disease-related death, ischemic stroke, transient ischemic attack) occurred in 41 subjects. After adjustment for age and comorbidity, PFO was not a significant independent predictor of stroke (hazard ratio 1.46, 95% confidence interval 0.74 to 2.88, p = 0.28). The risk of a cerebrovascular event among subjects with ASA was nearly four times higher than that in those without ASA (hazard ratio 3.72, 95% confidence interval 0.88 to 15.71, p = 0.074). CONCLUSIONS: These prospective population-based data suggest that, after correction for age and comorbidity, PFO is not an independent risk factor for future cerebrovascular events in the general population. A larger study is required to test the putative stroke risk associated with ASA.

Limited (6-h) ambulatory blood pressure monitoring is a valid replacement for the office blood pressure by trained nurse clinician in the diagnosis of hypertension.

OBJECTIVE: To assess the ability of limited ambulatory blood pressure monitoring as a valid replacement for office blood pressure measurement done to American Heart Association criteria in diagnosing hypertension. METHODS: In all, 105 adults, who had been referred for limited ambulatory blood pressure monitoring, participated in the study. Limited ambulatory blood pressure monitoring consisted of 6 h of blood pressure measurement while ambulatory at the Mayo Clinic, using a SpaceLabs 90207 (SpaceLabs Medical, Issaquah, Washington, USA) collecting six readings per hour for the period of observation. The study participants gave consent for three additional consecutive office blood pressure measurements, using a validated aneroid device, done to American Heart Association criteria, by a single hypertension nurse specialist. RESULTS: Mean systolic blood pressure by limited ambulatory blood pressure monitoring was 137.9+/-14.2 mmHg and for the nurse, 137.9+/-20.1 mmHg. Mean diastolic blood pressure by limited ambulatory blood pressure monitoring was 81.5+/-9.7 mmHg and for the nurse, 74.3+/-11.9 mmHg. The intermethod difference for systolic blood pressure was 0.03+/-12.5 mmHg and diastolic blood pressure, -7.2+/-8.0 mmHg. Using <140/90 as criteria factor, limited ambulatory blood pressure monitoring and the trained nurse agreed 77% of the time on whether the patient was hypertensive. This agreement increased to 81% if the participant's referral blood pressure was >or=140/90. CONCLUSIONS: Limited ambulatory blood pressure monitoring is an excellent replacement for office blood pressure, done to American Heart Association criteria, in diagnosing hypertension. This avoids issues of variability introduced by the observers, such as digit preference and bias, and increases reproducibility of blood pressure measurements. The appropriate normal value for limited ambulatory blood pressure monitoring is <140/90 mmHg compared with <135/85 mmHg used in 24-h ambulatory blood pressure monitoring.

Recommendations for blood pressure measurement in humans and experimental animals: part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research.

Accurate measurement of blood pressure is essential to classify individuals, to ascertain blood pressure-related risk, and to guide management. The auscultatory technique with a trained observer and mercury sphygmomanometer continues to be the method of choice for measurement in the office, using the first and fifth phases of the Korotkoff sounds, including in pregnant women. The use of mercury is declining, and alternatives are needed. Aneroid devices are suitable, but they require frequent calibration. Hybrid devices that use electronic transducers instead of mercury have promise. The oscillometric method can be used for office measurement, but only devices independently validated according to standard protocols should be used, and individual calibration is recommended. They have the advantage of being able to take multiple measurements. Proper training of observers, positioning of the patient, and selection of cuff size are all essential. It is increasingly recognized that office measurements correlate poorly with blood pressure measured in other settings, and that they can be supplemented by self-measured readings taken with validated devices at home. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. Twenty-four-hour ambulatory monitoring gives a better prediction of risk than office measurements and is useful for diagnosing white-coat hypertension. There is increasing evidence that a failure of blood pressure to fall during the night may be associated with increased risk. In obese patients and children, the use of an appropriate cuff size is of paramount importance.

Recommendations for blood pressure measurement in humans and experimental animals: Part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research.

Accurate measurement of blood pressure is essential to classify individuals, to ascertain blood pressure-related risk, and to guide management. The auscultatory technique with a trained observer and mercury sphygmomanometer continues to be the method of choice for measurement in the office, using the first and fifth phases of the Korotkoff sounds, including in pregnant women. The use of mercury is declining, and alternatives are needed. Aneroid devices are suitable, but they require frequent calibration. Hybrid devices that use electronic transducers instead of mercury have promise. The oscillometric method can be used for office measurement, but only devices independently validated according to standard protocols should be used, and individual calibration is recommended. They have the advantage of being able to take multiple measurements. Proper training of observers, positioning of the patient, and selection of cuff size are all essential. It is increasingly recognized that office measurements correlate poorly with blood pressure measured in other settings, and that they can be supplemented by self-measured readings taken with validated devices at home. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. Twenty-four-hour ambulatory monitoring gives a better prediction of risk than office measurements and is useful for diagnosing white-coat hypertension. There is increasing evidence that a failure of blood pressure to fall during the night may be associated with increased risk. In obese patients and children, the use of an appropriate cuff size is of paramount importance.

Atherosclerosis of the aorta: risk factor, risk marker, or innocent bystander? A prospective population-based transesophageal echocardiography study.

OBJECTIVES: The goal of this study was to investigate whether complex aortic atherosclerosis is associated with increased risk of vascular events in a non-selected population. BACKGROUND: In selected high-risk patients, aortic atherosclerosis is associated with increased risk of vascular events. METHODS: We describe the relationship between simple versus complex (>4-mm thick or mobile debris) aortic atherosclerotic plaques and vascular events during follow-up in a random sample of 585 persons (age > or =45 years) using 1993 to 2000 data from the Stroke Prevention: Assessment of Risk in a Community (SPARC), a prospective population-based longitudinal study. RESULTS: At five-year median follow-up (range, 0.5 to 6.5 years), cardiac events (death, non-fatal myocardial infarction, coronary revascularization, heart failure associated with coronary artery disease) and cerebrovascular events (ischemic fatal and non-fatal strokes, transient ischemic attacks) had occurred in 95 subjects and 41 subjects, respectively. Age, male gender, prior coronary artery disease, higher pulse pressure, and diabetes were significant cardiovascular predictors. Age, prior myocardial infarction, and a history of atrial fibrillation were significant cerebrovascular predictors. Simple aortic plaques (253 persons) were not independently associated with either cardiac or cerebrovascular events. Complex plaques (44 persons) were marginally associated with cardiac events, adjusting for age and gender (hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.11 to 4.68; p = 0.053 for two degrees of freedom [complex and simple plaques vs. no plaques]) but not after adjusting for additional clinical risk factors (HR, 1.22; 95% CI, 0.57 to 2.62; p = 0.64). Complex plaques were associated with cerebrovascular events only univariately. CONCLUSIONS: Aortic atherosclerotic plaques are not associated with future cardiac or cerebrovascular events. Aortic atherosclerosis may not be an independent risk factor for vascular events in the general population.

Does evidence-based medicine suggest that physicians should not be measuring blood pressure in the hypertensive patient?

The most common reason for an outpatient physician visit is for the diagnosis and treatment of hypertension. The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) VII, which is increasingly evidence-based, advises the clinician to use studies of the mean response and benefit derived from reduction in blood pressure (BP) from antihypertensive therapy and to translate this data into recommendations for the individual hypertensive patient. We believe that the increasingly aggressive approach to hypertension mandated by JNC VII calls into question the use of physician-measured BP. Ample evidence has shown that phycisians have not been adequately trained to measure BP and, therefore, rarely measure BP to the standards asked for by JNC VII or the American Heart Association (AHA) guidelines. In addition, the white coat effect dilutes the validity and usefulness of physician-measured BPs. Finally, in the evidenced-based studies used to derive the JNC VII guidelines, BPs were measured by nurses, other "trained observers," or automated devices, not physicians. Accurate BP measurement is critical to diagnosis and management of hypertension. We recommend, therefore, that for this purpose physicians should not measure BP themselves but should rely on BPs from well-trained and monitored observers or validated automated devices to improve the quality of care of the hypertensive patient.

The Accoson Greenlight 300, the first non-automated mercury-free blood pressure measurement device to pass the International Protocol for blood pressure measuring devices in adults.

BACKGROUND: Accurate blood pressure measurement is critical to successful care of the hypertensive patient. The mercury manometer is rapidly being removed from clinical practice due to concerns about environmental contamination. The Accoson Greenlight 300 device is the first non-automated mercury-free device for auscultatory blood pressure measurement to pass the International Protocol for validation of blood pressure measuring devices in adults. METHODS: Fifty-one patients were enrolled to obtain the 33 patients required to fill the three systolic blood pressure (SBP) ranges (low 90-129 mmHg, medium 130-160 mmHg, high 161-180 mmHg) and diastolic blood pressure (DBP) ranges (low 40-79 mmHg, medium 80-100 mmHg, high 101-130 mmHg). Nine sequential blood pressure measurements by two observers with the mercury manometer and the supervisor with the Greenlight 300 were taken. The first two observer blood pressures were used to classify the SBP and DBP range. The readings were then analyzed in two phases to determine whether the device passed the International Protocol. RESULTS: The device passed Phase 1 using 15 subjects. In Phase 2.1 (n=33) for the 99 readings of SBP, 84 of 99 were within 5 mmHg, 95 of 99 were within 10 mmHg, and 98 of 99 were within 15 mmHg. For the 99 readings of DBP, 74 of 99 were within 5 mmHg, 90 of 99 were within 10 mmHg, and 96 of 99 were within 15 mmHg. In Phase 2.2 (n=33) for SBP, 33 of 33 had 2 of 3 SBP within 5 mmHg and none had all three readings >or=5 mmHg. For DBP, 27 of 33 had 2 of 3 of their DBP within 5 mmHg and only three had all three readings > or =5 mmHg. CONCLUSIONS: The Accoson Greenlight 300 is the first electronic non-automated blood pressure measurement device to pass the International Protocol.

The changing distribution of arm circumferences in NHANES III and NHANES 2000 and its impact on the utility of the 'standard adult' blood pressure cuff.

BACKGROUND: Accurate blood pressure measurement is dependent on using a blood pressure cuff that is appropriate to the patient's arm circumference. OBJECTIVE: This study identifies the change in distribution of arm circumferences in the United States and its impact on usage of the 'standard adult' cuff. METHOD: The most current National Health and Nutritional Examination Survey (NHANES) data, available on the website (http://www.cdc.gov/nchswww/nchshome.htm), covers NHANES III (Cycle 1, 1988-1991; 8381 subjects and Cycle 2, 1991-1994; 8566 subjects) and NHANES 2000 (1999-2000; 4,444 subjects). The weighted change in arm circumference between NHANES III as a whole and NHANES 2000 was calculated. Correlates for increased arm circumference were obtained via multivariate analysis. The predicted change in blood pressure cuff usage based on the changing prevalence of arm circumferences was calculated. RESULTS: The mean arm circumference for the whole population increased significantly from NHANES III to NHANES 2000 (31.83 +/- 0.08 cm versus 32.86 +/- 0.15 cm, p < 0.001) and in the hypertension population without reaching statistical significance (33.07 +/- 0.16 to 33.61 +/- 0.30 cm, p = 0.11). When adjusted regressions were performed, the increases in arm circumference were due to increasing weight in both the whole population and the hypertensives. The numbers of Americans predicted to require the 'standard adult' cuff to accurately measure blood pressure decreased from 76.2% to 66.3% while the number of Americans increased from 42.2% to 45%. CONCLUSIONS: The increasing prevalence of overweight and obese Americans found in NHANES III and NHANES 2000 has led to larger mean arm circumferences in hypertensives and the total population. This increased frequency of larger arm circumferences predicts that the 'large adult' cuff will be increasingly required in clinician's offices for accurate blood pressure measurement.

Out of Office Self Measurement of Blood Pressure.

Self measurement of blood pressure is increasingly common among hypertensive patients. These out of office measurements are clinically useful in avoiding misdiagnosis of hypertension, over treatment and under treatment of hypertension, and as a measure to increase compliance and reduce the cost of antihypertensive therapy. This paper will address the clinical relevance of out of office blood pressure measurement related to hypertension management, the instruments available to perform out of office blood pressure measurement, and the current problems of interpretation of these blood pressure values as they relate to subsequent development of hypertension derived cardiovascular disease. (c)1999 by Le Jacq Communications, Inc.