Vital signs - Blood pressure (BP): Nursing skills

As a nurse, 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 between sexes since sex hormones like estrogen can have a protective effect on blood pressure; 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.