Abstracts

Archives of Internal Medicine, 2001 Mar 12; 161(5): 729-31
Are aneroid sphygmomanometers accurate in hospital and clinic settings?
Canzanello VJ, Jensen PL, Schwartz GL.
BACKGROUND: The aneroid sphygmomanometer is commonly used for the indirect measurement of blood pressure despite significant concerns about its accuracy. Although the mercury sphygmomanometer is highly accurate, there are concerns about the environmental toxicity of mercury. In response to various external pressures to become essentially mercury free, the Mayo Medical Center, Rochester, Minn, has replaced many mercury sphygmomanometers with aneroid devices. Since 1993, a maintenance protocol has been in place to ensure proper function and accuracy of these devices. METHODS: We assessed the accuracy of 283 aneroid devices using as the reference standard a digital pressure and vacuum meter that was calibrated using a mercury sphygmomanometer. RESULTS: The mean +/- SD values from the aneroid device in millimeters of mercury at each reference point (at 20-mm Hg intervals from 60 to 240 mm Hg defined by the reference device) were 59.9 +/- 1.9 at 60; 79.9 +/- 1.9 at 80; 100.0 +/- 1.8 at 100; 120.3 +/- 1.8 at 120; 140.7 +/- 1.4 at 140; 160.7 +/- 1.7 at 160; 180.9 +/- 1.3 at 180; 200.7 +/- 5.0 at 200; 221.0 +/- 1.3 at 220; and 240.8 +/- 1.6 at 240 (r = 0.99; P<.001). The values from the aneroid device underestimated those of the reference device by a mean of 0.5 mm Hg (95% confidence interval, 0.3-0.7). Virtually 100% of the values from the aneroid device were within the 4-mm Hg range recommended by the Association for the Advancement of Medical Instrumentation. CONCLUSION: Aneroid sphygmomanometers provide accurate pressure measurements when a proper maintenance protocol is followed

Journal of Human Hypertension, 2000 Jan; 14(1): 31-6
The mercury sphygmomanometer should be abandoned before it is proscribed.
Markandu ND, Whitcher F, Arnold A, Carney C.
Both in clinical practice and medical research, blood pressure is still largely measured by auscultation using a mercury sphygmomanometer. Blood pressure is the most important predictor of life expectancy. Treatment of high blood pressure reduces strokes, heart attack and heart failure. Accurate measurement is therefore essential. At a large London teaching hospital, just under 500 mercury sphygmomanometers and their associated cuffs were examined. More than half had serious problems that would have rendered them inaccurate in measuring blood pressure. At the same time, assessment of the technical knowledge needed to measure blood pressure by the ausculatory technique was also carried out amongst medical and nursing staff. This showed a considerable level of ignorance. These results inevitably lead to inaccurate measurement of blood pressure with serious consequences. In addition mercury is a non-degradable pollutant, eventually accumulating on the sea bed. The use of mercury in sphygmomanometers is already in the process of being eliminated in Scandinavia and Holland and other countries are likely to follow. Our results suggest that mercury sphygmomanometers are not adequately maintained and require expertise that is not available for accurate measurement of blood pressure. Their use should be dispensed with on these grounds before a ban for other and perhaps less justifiable reasons. Validated automatic devices, which are less liable to measurement and observer error should be used instead. At the same time a concerted effort is needed to instruct health care professionals on the importance of more accurate measurement of blood pressure. Journal of Human Hypertension (2000) 14, 31-36.

Journal of Human Hypertension, 1998 Apr; 12(4):245-8
How accurate are sphygmomanometers?
Mion D, Pierin AM.

The objective of this study was to assess the accuracy and reliability of mercury and aneroid sphygmomanometers. Measurement of accuracy of calibration and evaluation of physical conditions were carried out in 524 sphygmomanometers, 351 from a hospital setting, and 173 from private medical offices. Mercury sphygmomanometers were considered inaccurate if the meniscus was not '0' at rest. Aneroid sphygmomanometers were tested against a properly calibrated mercury manometer, and were considered calibrated when the error was < or =3 mm Hg. Both types of sphygmomanometers were evaluated for conditions of cuff/bladder, bulb, pump and valve. Of the mercury sphygmomanometers tested 21% were found to be inaccurate. Of this group, unreliability was noted due to: excessive bouncing (14%), illegibility of the gauge (7%), blockage of the filter (6%), and lack of mercury in the reservoir (3%). Bladder damage was noted in 10% of the hospital devices and in 6% of private medical practices. Rubber aging occurred in 34% and 25%, leaks/holes in 19% and 18%, and leaks in the pump bulb in 16% and 30% of hospital devices and private practice devices, respectively. Of the aneroid sphygmomanometers tested, 44% in the hospital setting and 61% in private medical practices were found to be inaccurate. Of these, the magnitude of inaccuracy was 4-6 mm Hg in 32%, 7-12 mm Hg in 19% and > 13 mm Hg in 7%. In summary, most of the mercury and aneroid sphygmomanometers showed inaccuracy (21% vs 58%) and unreliability (64% vs 70%).

Journal of Human Hypertension, 2001 Oct; 15(10): 681-4
Sphygmomanometers in use in general practice: an overlooked aspect of quality in patient care.
Knight T, Leech F, Jones A, Walker L, Wickramasinghe R, Angris S, Rolfe P.

OBJECTIVES: To assess the condition, accuracy and safety of mercury and aneroid sphygmomanometers in use in general practice and to pilot a scheme for sphygmomanometer maintenance within the district. DESIGN: Instruments were checked on site according to set protocols which related to established guidelines and standards and data were entered into a specially designed database. Mercury sphygmomanometers were removed to the laboratory for servicing. Practices received written feedback on the condition of each instrument checked, repairs undertaken and advice, where necessary, for further work required. Participant views on the scheme were sought. MATERIALS AND METHODS: A total of 472 instruments (75.4% mercury) located in 86 general practices (87.8% of practices participated) in a health district in the West Midlands. Instruments were checked against 28 (mercury) and 25 (aneroid) quality standards and (for mercury instruments) against British Hypertension Society guidelines. RESULTS: 69.1% of mercury and 95.7% of aneroid instruments checked, had no service records. Of the remainder, only 29 mercury (8.1%) and one aneroid (0.9%) had a record of a check or service within the previous 12 months. None of the instruments met all of the relevant quality standards and 14 (3.9%) mercury and seven (6.1%) aneroid instruments met less than half. A large proportion of mercury sphygmomanometers tested had defects likely to affect recommended measurement technique. Only two-thirds were accurate at all pressure levels tested. Only 38.8% of aneroid instruments were accurate at all test pressure levels. CONCLUSIONS: The level of defects noted could have an impact on diagnosis and monitoring of hypertension.

British Journal of General Practice, 1999 Feb; 49(439): 136-9
Pressure for change: unresolved issues in blood pressure measurement.
Aylett M.
The use of mercury is likely to be prohibited within a few years and clinicians have not yet seriously considered what sphygmomanometers they will use, nor is authoritative advice available on alternative instruments. Doubts also surround the thorny question of cuff size. Most blood pressures are taken in assessing cardiovascular health, and serial consulting room measurements may not be the best way of doing this. What is the role of continuous ambulatory monitoring in routine care? What is the place of home monitoring by patients, now that accurate and easy-to-use electronic sphygmomanometers are available?

List of Studies on the Efficacy of Non-Mercury Sphygmomanometers

Aylett M. Pressure for change: unresolved issues in blood pressure measurement. Br J Gen Pract, 49(439):136-9 (1999).

Bailey RH, Knaus VL, Bauer JH. Aneroid sphygmomanometers. An assessment of accuracy at a university hospital and clinics. Arch Intern Med, 151(7):1409-12 (1999)

Bottini PB, Carr AA, Prisant LM, Rhoades RB. Variability and similarity of manual office and automated blood pressures. J Clin Pharmacol, 32(7):614-9 (1992).

Brinton TJ, Walls ED, Yajnik AK, Chio SS. Age-based differences between mercury sphygmomanometer and pulse dynamic blood pressure measurements. Blood Press Monit, 3(2):125-129 (1998).

Burke MJ. An electronic manometer for blood-pressure measurement. J Med Eng Technol. 16(6):197-202 (1999).

Canzanello VJ, Jensen PL, Schwartz GL. Are Aneroid Sphygmomanometers Accurate in Hospital and Clinic Settings? Arch Intern Med. 2001; 161:729-731.

Gonzalez Biosca MD, Fernandez-Cruz A, Mizushima S, Yamori Y. Correlation between objective automatic and auscultatory mercury manometer blood pressure measurements. J Cardiovasc Pharmacol. 16(Suppl 8):S26-7 (1990).

Gourlay SG, McNeil JJ, Marriner T, Farish SJ, Prijatmoko D, McGrath BP. Discordance of mercury sphygmomanometer and ambulatory blood pressure measurements for the detection of untreated hypertension in a population study. J Hum Hypertens, 7(5):467-72 (1993).

Markandu ND, Whitcher F, Arnold A, Carney C. The mercury sphygmomanometer should be abandoned before it is proscribed. J Hum Hypertens, 14(1):31-6 (2000).

Mion D, Pierin AM. How accurate are sphygmomanometers? J Hum Hypertens, 12(4):245-8 (1998).

Padfield PL. The demise of the mercury sphygmomanometer. Scot Med J 43):1185-1189 (1998).

Prisant LM, Alpert BS, Robbins CB, Berson AS, Hayes M, Cohen ML, Sheps SG. American National Standard for non-automated sphygmomanometers. Summary report. Am J Hypertens, 8(2):210-3 (1995).

Rennie AC, McGregor-Schuerman M, Dale IM et al. Mercury poisoning after spillage at home from a sphygmomanometer on loan from hospital. Brit Med J 319(7206):366-377 (1999).

Rogers P, Burke V, Stroud P, Puddey IB. Comparison of oscillometric blood pressure measurements at the wrist with an upper-arm auscultatory mercury sphygmomanometer. Clin Exp Pharmacol Physiol, 26(5-6):477-81 (1999).

Smith GR. Devices for blood pressure measurement. Prof Nurse. 2000 15(5):337-40 (2000).

Stewart MJ, Padfield PL. Blood pressure measurement: an epitaph for the mercury sphygmomanometer? Clin Sci (Colch), 83(1):1-12 (1992).

Stewart MJ, Padfield PL. Measurement of blood pressure in the technological age. Br Med Bull, 50(2):420-42 (1994).

Suzuki K, Matsunago K. Umeuura Y et al. 2 cases of occupational dermatitis due to mercury vapor from a broken sphygmomanometer. Contact Dermatitis 43(3): 175-177 (2000).

van Egmond J, Lenders JW, Weernink E, Thien T. Accuracy and reproducibility of 30 devices for self-measurement of arterial blood pressure. Am J Hypertens. 6(10):873-9 (1993).

White WB. Accuracy and analysis of ambulatory blood pressure monitoring data. Clin Cardiol. 1992 Oct;15(5 Suppl 2):II10-3 (1992).