Sphygmomanometers

6. Will alternative devices affect health care and research?

• 6.1 Clinical use
• 6.2 Research

6.1 Clinical use

There is no evidence of any adverse clinical effects on patients’ health when properly validated alternatives to mercury-containing sphygmomanometers are used in the clinic. The alternatives are generally adequate in a wide range of conditions. For a few conditions and types of patients, only some of the alternatives are suitable. This applies in particular to anyone whose arteries may have different elasticity (more or less) than normal. This can arise for a variety of different reasons, in patients including the elderly, those with heart arrhythmia s such as atrial fibrillation , and in diabetes. In these cases, and in monitoring for pre-eclampsia in pregnant women, and blood pressure measurements in children, oscillometric devices may not be ideally suited for general use. Non-mercury auscultatory devices are thus recommended for use in these patients until further validation of other alternatives. Electronic non-mercury auscultatory devices are suitable for such patients.

There may also be benefits from use of the alternative devices. Oscillometric devices have encouraged use of home surveillance of blood pressure through self-measurement and 24 hour ambulatory monitoring. This has been shown to be more reproducible than measurements taken in the doctor’s office or in the clinic, and to offer better prediction of cardiovascular risks, and reliable when used by non-clinicians.

6.2 Research

In epidemiology , the vast majority of information on population blood pressure, including long-term trends, how high blood pressure develops in individuals and its predictive value, and the benefits of reducing blood pressure, has come from use of mercury sphygmomanometers. Getting reliable data on changes in populations in long-term follow up depends on using consistent measurement methods. Future epidemiological and observational studies are likely to use repeated blood pressure measurements at home using well-calibrated automatic oscillatory equipment. Such devices also have the advantage that they can store data for later analysis. A number of long-term outcome studies are already using automated technology to measure blood pressure instead of the traditional mercury "gold standard”. For the moment, however, mercury sphygmomanometers are essential for validation of newly developed devices. Otherwise, conclusions from the results of long-term studies on changes on population blood pressure may be seriously jeopardised.