Mean Arterial Pressure

How do you calculate mean arterial pressure?

This number is often calculated via complex formulas or invasive monitoring techniques. There are two relatively easy to use formulas that can get a close estimation without monitoring equipment.
The first formula is: Double the diastolic blood pressure and add that to the systolic blood pressure. Divide by 3.
The second formula is: Calculate pulse pressure by subtracting the diastolic blood pressure from the systolic blood pressure. Divide that number by 3, then add the diastolic blood pressure.

What is blood pressure?

Blood pressure, in general, references the pressure at which the blood is propelled throughout the body and vessels by the heart.
It’s broken down into systolic and diastolic blood pressure readings. The systolic blood pressure refers to the amount of pressure against the arterial walls when the heart beats. Diastolic blood pressure is referring to the amount of pressure against the arterial walls between heartbeats.
Things like stress, hardening of the arteries, medications, exercise and lifestyle choices can impact a patient’s blood pressure.
In medical settings, blood pressure is often calculated or notated in mm Hg, or millimeters of mercury. This is because the gauges that were first used for recording blood pressure used to use mercury.

What is Mean Arterial Pressure (MAP)?

This number is referring to the average pressure recorded in a patient’s arteries during one full cardiac cycle. The cardiac cycle includes the heartbeat as well as the rest in between. That’s why systolic and diastolic blood pressures are used in calculating this number.

Why is mean arterial pressure important?

This number is indicative of many things in the circulatory system and body as a whole. It’s a good way to assess possible blood perfusion levels in the body. When a person’s numbers are good, they are in a healthy range and their heart and circulatory system are functioning in a healthy manner.
Medically speaking, this number is important to doctors and nurses because it directly impacts care. They need to know the dosages of medications that effect the blood pressure, such as vasopressors or vasodialators. With head injuries or stroke, this must be monitored to make sure the blood pressure throughout the patient’s body is not too high or low for the recovery.

What is a high MAP?

The medical definition of a high range number is over 100 mmHg. This shows a significant amount of pressure throughout the circulatory system. If a patient has an abnormally elevated blood pressure, especially for a considerable amount of time, there can be medical consequences.
Some consequences patients can experience with high pressure include things like:

  • Heart failure
  • Heart overwork
  • Kidney failure
  • More prone to suffer a heart attack

When the pressure is too high, medical professionals may administer drugs to lower blood pressure, including nitroglycerin. After this, the doctors and nurses can treat the underlying causes, which might be things like blood clots or other arterial blockages. The patient may require a stent or stents to assist in restoring blood flow and lowering the blood pressure.

What is a low MAP?

To receive a medical diagnosis of a low number, the patent’s arterial pressure must be less than 60 mmHg. This means the pressure within the patient’s circulatory system is inadequate to maintain proper blood perfusion to the tissues, among other possible issues. When a patient has a low pressure for a sustained amount of time, they may be experiencing or be at risk of:

  • Internal bleeding
  • Sepsis
  • Stroke
  • Necrotic tissues

There are various courses of treatment that medical professionals can utilize to raise the number. If the patient is suffering internal bleeding, they will require blood product transfusions to stabilize.
If the low number isn’t due to internal bleeding, the patient may be given medications called vasopressors to tighten the blood vessels as another means to bring the number and blood pressure up for the patient. This will ensure all the tissues of the body are getting blood and nutrients to them and keep the patient safe.

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