Tough question! When measured by a trained professional, following AHA recommendations for blood pressure measurement, a manual instrument will produce very accurate results. Today, home digital BP monitors are VERY accurate, but they do have limitations. Because the algorithms used to calculate blood pressure are based on a limited number of clinical observations, there are people for whom digital units simply will not work.

ADC digital sphygs have a pressure sensor self test that is activated each time you power on the instrument. If the microprocessor detects anything wrong with either the pressure sensor or the chip that analyzes the readings, an error message will be displayed BEFORE measurement. If the unit beeps and displays 0, you can be confident in the instrument's accuracy.

A variety of reasons. First of all, blood pressure itself is a dynamic rather than static vital sign. Both systolic and diastolic pressures can vary from 10mmHg to 20mmHg or more throughout the course of the day. In some people, a lot more than that. BP is generally lower in the morning and increases throughout the day. Eating, drinking, smoking, exercise and even talking all influence blood pressure. Instrument repeatability will also result in measurement variance.

Although unlikely to occur with an ADC DIAGNOSTIX mercury sphyg, it can happen. ADC mercury sphygs hold just 2 oz of 99.9999% pure elemental mercury and can easily be contained with a mercury spill kit available through ADC or most laboratory and safety supply dealers. A mercury spill kit should be kept on the premises WHEREVER mercury instruments are used. Never use vacuums which may disperse mercury vapor. Always wear gloves and dispose of contained mercury in accordance with local regulations.

This condition will generally only occur on older latex style blood pressure devices. The phenomenon, known as frosting, is a chemical reaction caused by the exposure of latex to the ozone. Fluorescent lighting can exacerbate the problem. When properly cured during the manufacturing process latex should not frost. However, it can be difficult to determine optimal curing times which are dependent on ambient temperature, humidity, and the water content of the liquid latex.

Although properly designed mercurial instruments are required to provide a full pressure drop (300 mmHg to 20 mmHg with no back pressure) in 3 seconds, older instruments tend to slow down due to build up of dust or other obstructions within the system. This slow down will produce a lag - the air will release from the cuff FASTER than the mercury can drop in the column. In addition, some manufacturers whose cartridge tubes have a narrow inside bore (generally less than the mandated 3.9 mm dimension) will always suffer from some lag.

The only way to be 100% sure is to connect the manometer in series to an instrument of known accuracy and test during deflation at a variety of pressures (i.e. 300, 260, 180, 120, 60, etc.) When testing your sphygmomanometer, it is important that you check the accuracy in accordance with national or international standards that may be applicable to your device.

Yes and no. Some mercury compounds - mercury chemically bonded to other elements can be quite toxic. On the other hand, 99.9999% pure elemental liquid mercury will not be absorbed within the system. In fact, if accidentally ingested it will pass. However, prolonged exposure to elemental mercury vapor is very dangerous. ADC mercury blood pressure instruments contain less than 2 oz of elemental mercury and pose no measurable health risk.

If new, the unit must be within 3mmHg when tested against a reference instrument in order to meet ANSI/AAMI/ISO 81060 standards. ADC's PROSPHYG series instruments will always meet or exceed these standards. ADC's DIAGNOSTIX series manometers exceed these standards by as much as 66%. ADC DIAGNOSTIX brand mercury manometers are guaranteed to be within 1mmHg over their full range, while the DIAGNOSTIX brand aneroid manometers are guaranteed within 2mmHg when NEW.

It is critical. When the inside bore is too narrow two problems can result; mercury lag and mercury separation. Mercury lag is the phenomenon that occurs when the air deflates from the cuff faster than the mercury column can respond. When the forces of friction (of the mercury against the inner walls of the cartridge tube) that prevent the mercury from dropping exceed the gravitational forces, this causes the mercury to drop and results in mercury lag. That same friction can actually cause the column of liquid mercury to split - forcing an air pocket that will distort readings.