Cardiovascular: Blood pressure (for nursing assistant training)

As a nursing assistant, you will need to measure your client’s blood pressure.

Blood pressure refers to the force that the blood exerts on the walls of the arteries.

Now, a blood pressure measurement has two values.

The first and the highest is the systolic blood pressure, which is the force that the blood exerts on the walls of the arteries during systole, or when the heart contracts to pump blood through the body.

The second one is the diastolic blood pressure, which is the pressure on the walls of the arteries during diastole, or when the heart relaxes and refills with blood between heartbeats.

Now, maintaining normal blood pressure is essential to ensure that tissues around the body are receiving an adequate amount of oxygen and nutrients from the blood.

If blood pressure gets too low, the brain, heart, and other vital organs might stop functioning normally because they’re not getting enough blood.

In contrast, blood pressure that is too high, can create a serious problem for the blood vessels and the organs they supply.

Just like a garden hose that’s always under high pressure, in the long term, blood vessels may develop tiny cracks and tears that can lead to serious problems, like myocardial infarctions, or heart attacks; strokes, or brain attacks; and aneurysms, or bulges of a weakened blood vessel wall. Increased blood pressure can damage small blood vessels, like those seen in the kidney and eyes, leading to kidney failure and vision loss.

Chronic increased blood pressure also makes it hard for the heart to pump blood out against the increased pressure.

Over time, the heart gets overworked and this can lead to heart failure.

There are several factors that can increase or decrease blood pressure.

The first factor is the cardiac output, which is the total volume of blood the heart ejects in one minute.

The more blood the heart pumps out, the higher the blood pressure.

The cardiac output depends mainly on the heart rate, or the number of times the heart beats per minute; the contractility, or how forcefully the heart contracts with each beat; as well as the total volume of blood circulating throughout the entire body at that time.

Another factor influencing the blood pressure is resistance, which refers to the physical and mechanical pushback the blood gets from things like vasoconstriction, or narrowing of the blood vessel.

The more narrow the blood vessel, the higher the blood pressure.

Now, blood pressure may also vary depending on the biological sex, where biological males typically have a higher blood pressure than biological females; ethnicity, where people of African descent are likely to develop higher blood pressure; as well as different age groups, where blood pressure typically goes up with age.

Other factors include obesity, stress, pain, smoking, and alcohol. It is also important to recognize that blood pressure in any client is highly variable.

This means blood pressure readings often differ by the time of day, so they’re typically lowest in the morning and following a meal, especially if it’s high in salt.

Also, the readings may vary by the season and by other factors; for example, they may increase with physical activity, fear, or pain and decrease when the person is lying down.

So, for those 13 years and older, they normally have a systolic blood pressure of less than 120 millimeters of mercury, or mmHg, and a diastolic blood pressure of less than 80 mmHg.

For school-aged children between 5 and 12 years old, systolic blood pressure is 84 to 120 mmHg, and diastolic blood pressure is 54 to 80 mmHg.

Preschoolers from 3 to 5 normally have a systolic blood pressure of 82 to 110 mmHg and a diastolic blood pressure of 50 to 78 mmHg.

Toddlers from 1 to 3 have a normal systolic blood pressure of 80 to 112 mmHg and a diastolic pressure of 50 to 80 mmHg.

Finally, infants under 1 year of age normally have the lowest blood pressure, which ranges from 74 to 100 mmHg systolic and 50 to 70 mmHg diastolic.

So, hypertension is defined as persistently higher than normal values of blood pressure, which, in adults, means 130 mmHg or more for the systolic blood pressure and 80 mmHg or more for the diastolic blood pressure.

On the other hand, hypotension for adults is when blood pressure falls below 90 mmHg for the systolic and 60 mmHg for the diastolic.

A variant of that is orthostatic hypotension, which is when blood pressure falls when a person goes from a lying down position to a standing position.

This is more common in the eldely, and these clients could experience lightheadedness and fainting when they stand or sit up due to decreased blood flow to the brain.

Now, when you’re asked to measure a client’s blood pressure, there are some common tips you need to remember.

Do not take the blood pressure on an arm that’s injured, in a cast, or has an IV or dialysis access site.

Even if we measure blood pressure under the same conditions, a client’s blood pressure may vary.

Now, for an accurate measurement, ensure that the client is in a comfortable position and not talking, remains calm, and hasn’t recently smoked or consumed caffeine.

It is also important to choose the proper cuff size for the client.

An overly small cuff causes the blood pressure to read too high, while an overly large cuff causes the blood pressure to read too low.

The width of the cuff’s bladder should amount to about 40% of the circumference of the upper arm, and the length of the cuff’s bladder should amount to no less than 80% of the circumference of the upper arm.

The arm should also be held at the heart level. If it’s held too low, the blood pressure might read higher than it really is.

If it’s held too high, the blood pressure might read lower than it really is.

If the cuff is wrapped too loosely, it’s the same story: The reading might come out too high.

If the cuff is deflated too slowly, then the diastolic blood pressure might read higher than it really is.

If the cuff is deflated too quickly, the diastolic blood pressure might read too high and the systolic blood pressure too low.

Finally, if the cuff isn’t inflated enough, the systolic blood pressure might again read too low.

Before taking a client's blood pressure, check with the care plan and the nurse to find out when and how often the blood pressure should be measured.