Blood Pressure Units

Blood Pressure Units

A blood pressure unit is used to determine the pressure inside the blood vessels of a patient.  There are two numbers that are important when taking a patient’s blood pressure, they are the systolic and diastolic pressures.  The systolic pressure is higher than the diastolic in a healthy adult and it corresponds to when the heart contracts.  While the diastolic number corresponds to when the heart is relaxed between beats.  Blood pressure readings are read as a fraction in a way for example 120/80 or 120 over 80 and readings can be classified as either low, normal, or high.  A person with low blood pressure has a blood pressure lower than 90/60 and the only real risk associated with this being that the patient may feel light headed or faint if it gets too low.  Normal blood pressure is any reading that is higher than 90/60 and lower than 140/90.  High blood pressure is any reading higher than 140/90 there are many health risks associated with high blood pressure and any patient with a blood pressure on the high side should consider changing their lifestyle.
How it works

There are two different types of blood pressure units either an automatic or a manual but they both work on the same principle.  First, the cuff is wrapped around the patients arm then the cuff is inflated to a point where it cuts off flow.  Next, the pressure in the cuff is slowly deflated until vibrations or Korotkoff sounds are heard.  When the sounds are first heard this is the systolic pressure of the patient and when the sounds stop this is the diastolic pressure.

Preventative Maintenance

The preventative maintenance of a blood pressure unit consists of, if applicable, an electrical safety inspection followed by a physical inspection of the unit and all accessories.  Next the blood pressure unit is tested for accuracy at different blood pressures and the system is tested for leaks.  Finally, the battery is checked to ensure that it has been changed within the past 2 years.  This is done for 2 reasons the first being so the battery does not corrode and damage the inside electronics.  The second reason being, so there is a functional battery in case of an emergency.

Common Errors

Electrical safety – Electrical safety failures are failures found during electrical safety testing and can potentially pose a risk to the patient.  This may be a high leakage current, ground wire resistance or too high of an operating current.

Damaged cuff or air hose – A damaged blood pressure cuff or air hose is common especially in a device that is highly used and this is because the Velcro gets worn to a point where it will not hold properly. Blood pressure units also develop leaks over time in the cuff itself or in any of the connectors used to interface the cuff with the air hose.  These failures can result in an error or false readings.

Internal Malfunctions – An internal malfunction of a blood pressure unit typically is one of 3 things.  First, the motor on the unit may fail; this will cause the cuff to not inflate fast enough or at all.  Second, is the pressure transducer which is responsible for reading the pressure inside the circuitry and detecting the vibrations of the patient’s blood pressure. The final internal error that can occur is an internal leak which may give the same errors and false readings as a leaky cuff.

Calibration failure – If a unit will not calibrate when attempted it can be caused by a main board failure, pressure transducer failure or because of a leak in the system.  When any of these typically the unit will need to be further assessed to determine exactly what is the cause.

How to get an accurate measurement

• Allow the patient to rest for 5 minutes or more with their arm at heart level and their feet flat on the floor.
• Find the right cuff for the patient as there are multiple sizes for patients with different size arms (If the patient fits in 2 cuff sizes pick the smaller of the 2).
• Wrap the cuff around the arm with the artery marker in line with the patient’s brachial artery so you can comfortably fit one finger under the cuff.
• Inflate the cuff and instruct the patient to no talk or make any sudden movements as this can mimic Korotkoff sounds and give false reading.
• If more even more accurate readings are desired repeat the process on both arms and average the total.

The TRH Value

The added valve of choosing TRH Services to complete your maintenance and repairs on your blood pressure units is that we will ensure that your device will be in great working condition for you and your patients for the next year and it will be fully certified.  At TRH Services our expertise can help educate you on your blood pressure systems and make sure that your unit is in top performance. We can provide onsite service to your facility if you are located in South-Western Ontario (London, Toronto, Kitchener, Waterloo, Cambridge, Guelph, Hamilton, etc.).

Common Blood Pressure Units

Listed below is a short list of some common blood pressure units that we work on, a regular basses:

Written By: Greg Kishimoto

Edited By: Tyler Hasenpflug CET