Does changing from mercury to electronic blood pressure measurement influence recorded blood pressure? An observational study.
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Mercury sphygmomanometers have been commonly used in primary care to measure blood pressure but are associated with bias. Electronic blood pressure machines are being introduced in many practices and have anecdotally been associated with higher recorded blood pressure. This study examined recorded blood pressure in four practices before and after electronic blood pressure machine introduction. No consistent change in mean blood pressure was apparent following their introduction, but there was a large and significant fall in terminal digit preference suggesting improved precision of recording. (+info)
Age and gender affect ventricular-vascular coupling during aerobic exercise.
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OBJECTIVES: The goal of this study was to examine the age-associated differences in ventricular-vascular coupling, defined by the ratio of arterial elastance (EaI) to left ventricular systolic elastance (E(LV)I), and its components, at rest and during exercise. BACKGROUND: Ejection fraction (EF) increases during exercise, but the EF reserve decreases with aging. Ejection fraction is inversely related to EaI/E(LV)I, an index of the interaction between arterial and ventricular properties, which is an important determinant of cardiac performance. Thus, age differences in EaI/E(LV)I during exercise, due to age differences in EaI, E(LV)I, or both, may help to explain the age deficit in EF reserve. METHODS: We noninvasively characterized EaI/E(LV)I = end-systolic volume index (ESVI)/stroke volume index (SVI) and its two determinants EaI = end-systolic pressure/SVI, and E(LV)I = end-systolic pressure/ESVI, at rest and during exercise in 239 healthy men and women (age range, 21 to 87 years). Blood pressures were assessed with cuff sphygomanometry, and cardiac volumes with gated blood pool scintingraphy. RESULTS: Resting EaI/E(LV)I was not age related in men or women. In both sexes, EaI/E(LV)I decreased during exercise and declined to a lesser extent in older subjects. There were gender differences in the components of EaI/E(LV)I during exercise: EaI was greater in older versus young women (p = 0.01) but was unaffected by age in men. Left ventricular systolic elastance increased to a greater extent in young versus older subjects (p = 0.0001 for men, p = 0.07 for women). CONCLUSIONS: Age-associated differences in EaI/E(LV)I occur in both genders during exercise. Sub-optimal ventricular-vascular coupling helps to explain the age-associated blunting of maximal exercise EF, and its underlying mechanisms appear to differ between men and women. (+info)
Sphygmomanometers--an audit in general practice.
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BACKGROUND: The accuracy of sphygmomanometers used in Australian general practice is unknown but potentially important. METHOD: We measured the accuracy of sphygmomanometers in general practice in the Hunter region of New South Wales using a gold standard. Practices were recruited by an advertisement in the division newsletter. RESULTS: Sixty practices (35%) volunteered. A total of 404 instruments were checked. Over 95% of sphygmomanometers were within 4 mmHg of gold standard sphygmomanometer across the clinical pressure range. Mercury sphygmomanometers were more accurate than aneroid (p<0.01). There was no significant association between accuracy and age, calibration, or visual inspection of the instruments. DISCUSSION: This study demonstrated a high accuracy rate of the sphygmomanometers checked, especially those sphygmomanometers that were mercury. (+info)
Reliability of automated blood pressure devices used by hypertensive patients.
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Automated blood pressure (BP) devices are used by many hypertensive patients in Hong Kong, with or without medical advice. At two community clinics, we invited hypertensive patients aged between 40 and 70 years who used such a device to fill in a questionnaire and to have four sets of BP measurements, automated and mercury, at two visits. Of 290 hypertensive patients 120 fulfilled the criteria, and 73 of these agreed to participate. 53 devices measured arm BP, 21 measured forearm BP. The agreement between the mercury sphygmomanometer and the automated devices was poor, with average differences of 9.5 mmHg for systolic and 9.4 mmHg for diastolic and no clear advantage for either site of measurement. As a means of screening for BP >140/90 mmHg the sensitivity of the automated devices was 81% and the specificity was 80%. There were large variations in how often and under what circumstances the devices had been used. One-fifth of the devices had been acquired on medical advice but only 11% of the participants were aware of the three important conditions for operating such devices. Discussion of automated devices, their role and proper use, should now be part of routine hypertensive care. (+info)
How well do clinic-based blood pressure measurements agree with the mercury standard?
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BACKGROUND: Obtaining accurate blood pressure (BP) readings is a challenge faced by health professionals. Clinical trials implement strict protocols, whereas clinical practices and studies that assess quality of care utilize a less rigorous protocol for BP measurement. OBJECTIVE: To examine agreement between real-time clinic-based assessment of BP and the standard mercury assessment of BP. DESIGN: Prospective reliability study. PATIENTS: One hundred patients with an International Classification of Diseases-9th edition code for hypertension were enrolled. MEASURES: Two BP measurements were obtained with the Hawksley random-zero mercury sphygmomanometer and averaged. The clinic-based BP was extracted from the computerized medical records. RESULTS: Agreement between the mercury and clinic-based systolic blood pressure (SBP) was good, intraclass correlation coefficient (ICC)=0.91 (95% confidence interval (CI): 0.83 to 0.94); the agreement for the mercury and clinic-based diastolic blood pressure (DBP) was satisfactory, ICC=0.77 (95% CI: 0.62 to 0.86). Overall, clinic-based readings overestimated the mercury readings, with a mean overestimation of 8.3 mmHg for SBP and 7.1 mmHg for DBP. Based on the clinic-based measure, 21% of patients were misdiagnosed with uncontrolled hypertension. CONCLUSIONS: Health professionals should be aware of this potential difference when utilizing clinic-based BP values for making treatment decisions and/or assessing quality of care. (+info)
The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis.
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OBJECTIVE: It has been previously shown that the SCD Response Compression System, by sensing the postcompression refill time of the lower limbs, delivers more compression cycles over time, resulting in as much as a 76% increase in the total volume of blood expelled per hour. Extended indications for pneumatic compression have necessitated the introduction of portable devices. The aim of our study was to test the hemodynamic effectiveness of a new portable sequential compression system (the SCD Express), which has the ability to detect the individual refill time of the two lower limbs separately. METHODS: This was an open, controlled trial with 30 normal volunteers. The new SCD Express was compared with the SCD Response Compression System in the supine and semirecumbent positions. The refilling time sensed by the device was compared with that determined from velocity recordings of the superficial femoral vein using duplex ultrasonography. Baseline and augmented flow velocity and volume flow, including the total volume of blood expelled per hour during compression with the SCD Express, were compared with those produced by the SCD Response compression system in the same volunteers and positions. RESULTS: Both devices significantly increased venous flow velocity as much as 2.26 times baseline in supine position and 2.67 times baseline in semirecumbent position (all P < .001). There was a linear relationship between duplex ultrasonography-derived refill time and the SCD Express-derived refill time in both the supine (r = 0.39, P = .03) and semirecumbent (r = 0.71, P < .001) positions but not with the SCD Response. Refill time measured by the SCD Express device was significantly shorter and the cycle rate higher in comparison with the SCD Response in both positions. The single-cycle flow velocity and volume flow parameters generated by the two devices were similar in both positions. However, median (interquartile range) total volume of blood expelled per hour was slightly higher with the SCD Express device in the supine position (7206 mL/h [range, 5042-8437] vs 6712 mL/h [4941-10,676]; P = .85) and semirecumbent position (4588 mL/h [range, 3721-6252] vs 4262 mL/h [3520-5831]; P = .22). Peak volume of blood expelled per hour by the SCD Express device in the semirecumbent position was significantly increased by 10% in comparison with the SCD Response (P = .03). CONCLUSIONS: Flow velocity and volume flow enhancement by the SCD Response and SCD Express were essentially similar. The latter, a portable device with optional battery power that detects the individual refill time of the lower limbs separately, is anticipated to be associated with improved overall compliance and therefore optimized thromboprophylaxis. Studies testing its potential for improved efficacy in preventing deep vein thrombosis are justified. (+info)
Validity of measures is no simple matter.
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PURPOSE AND METHOD: This article aims to promote a better understanding of the nature of measurement, the special problems posed by measurement in the social sciences, and the inevitable limitations on inferences in science (so that results are not overinterpreted), by using the measurement of blood pressure as an example. As it is necessary to raise questions about the meaning and extent of the validity of something as common as measured blood pressure, even more serious questions are unavoidable in relation to other commonly used measures in social science. The central issue is the validity of the inferences about the construct rather than the validity of the measure per se. CONCLUSION: It is important to consider the definition and validity of the construct at issue as well as the adequacy of its representation in the measurement instrument. By considering a particular construct within the context of a conceptual model, researchers and clinicians will improve their understanding of the construct's validity as measured. (+info)
Initial injection pressure for dental local anesthesia: effects on pain and anxiety.
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This study quantitatively assessed injection pressure, pain, and anxiety at the start of injection of a local anesthetic into the oral mucosa, and confirmed the relationship between injection pressure and pain, as well as between injection pressure and anxiety. Twenty-eight healthy men were selected as subjects and a 0.5-inch (12 mm) 30-gauge disposable needle attached to a computer-controlled local anesthetic delivery system (the Wand) was used. A 0.5 mL volume of local anesthetic solution was injected submucosally at a speed of either 30 or 160 s/mL. Three seconds after the start of local anesthetic injection, injection pressure was measured and pain and anxiety were assessed. Injection pressure was measured continuously in real time by using an invasive sphygmomanometer and analytical software, and pain was assessed on the Visual Analogue Scale and anxiety on the Faces Anxiety Scale. A significant correlation was evident between injection pressure and pain (rs = .579, P = .00124) and between intensity of injection pressure and state anxiety (rs = .479, P = .00979). It is therefore recommended that local anesthetic be injected under low pressure (less than 306 mm Hg) to minimize pain and anxiety among dental patients. (+info)