Blood Pressure

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Blood pressure is the force that blood exerts on vessel walls, as it circulates throughout the body to deliver nutrients and oxygen to tissues and organs. When measuring your patient’s blood pressure, you will follow the steps of the Clinical Judgment Measurement Model, or CJMM, to make clinical decisions about patient care.

Okay, let’s review the physiological regulation of blood pressure. First, when the heart contracts and pumps blood through the body during systole, the blood pressure rises. On the other hand, when the heart relaxes and refills with blood during diastole, the blood pressure decreases.

In addition to the heart, there are other internal factors that regulate blood pressure. The elastic arteries maintain blood pressure and help propel blood forward through the body by expanding and recoiling with each heartbeat. In addition, the autonomic nervous system can increase the blood pressure by increasing the heart rate and by causing vasoconstriction, where the arteries constrict, or it can decrease blood pressure by lowering the heart rate and by causing vasodilation, where the arteries relax.

Blood pressure is also influenced by hormones, like the renin-angiotensin-aldosterone system, which increases blood pressure by causing vasoconstriction and increasing the circulating blood volume; and through antidiuretic hormone, which also increases blood volume.

There are also some external factors that can increase blood pressure, too, like aging, which causes arteries to become stiffer and less compliant; and emotions, like anger and pain, which can stimulate the autonomic nervous system.

Now, blood pressure is measured in millimeters of mercury, or mm Hg for short; and is written as a fraction, like 118 over 72. In this example, 118 represents the systolic, or peak pressure in the arteries during systole; whereas 72 represents the diastolic, or lowest pressure in the arteries during diastole. Blood pressure can be measured manually, electronically, or even palpated from the brachial artery in the upper arm.

Alright, when assessing your patient’s blood pressure, you will use the Clinical Judgment Measurement Model to gather and recognize important cues, including the blood pressure reading, measurement site, equipment used, as well as the patient’s age, health conditions, and baseline blood pressure.

Sources

  1. "Fundamentals of Nursing" Elsevier (2020)
  2. "Fundamentals of Nursing" Elsevier (2022)