Chapter 5: Blood Pressure
Hypertension
Chronically elevated blood pressure (BP) is known clinically as hypertension. It is typically defined as chronic and persistent blood pressure measurements of 140/90 mm Hg or above (OER #2) in the adult. However, the specific measurement in which hypertension is diagnosed depends on many factors. As per Hypertension Canada (Rabi et al., 2020), some of these factors include whether it is the first or second visit to have blood pressure assessed and whether the blood pressure is assessed using automatic or manual measurement devices. As per Hypertension Canada (Rabi et al., 2020), blood pressure is considered high when the mean is greater than or equal to 135/85 when measured with automated office BP and greater than or equal to 140/90 with manual measurement in office.
It is always important to look at the most current guidelines related to hypertension. See Table 5.3 for the guidelines related to management, including monitoring and treatment, recommended by Hypertension Canada (Nerenberg, et al., 2018).
Hypertension is typically a silent disorder, so hypertensive clients may not recognize the seriousness of their condition and not adhere to their treatment plan. The result is often a heart attack or stroke. Hypertension may also lead to an aneurysm (ballooning of a blood vessel caused by a weakening of the wall), peripheral arterial disease (obstruction of vessels in peripheral regions of the body), chronic kidney disease, or heart failure. (OER#2)
Common errors in measurement and natural fluctuations in blood pressure can result in readings that erroneously suggest hypertension. Some of the errors are due to the operator (i.e., the healthcare provider) and others are due to client anxiety and situational determinants. As a healthcare provider, it is important to review your technique to assess possible measurement errors and assess the client for factors that could elevate blood pressure. If the client’s blood pressure is elevated, repeat the measurement for accuracy and take the blood pressure in the opposite arm.
Because hypertension is a silent disorder, healthcare providers measure blood pressure at regular intervals. The intervals depend on the client’s health status and risk factors. Before a diagnosis of hypertension is made, blood pressure is monitored over days, weeks, or months either in the office using an automatic blood pressure machine, or at home using an ambulatory blood pressure machine.
Clients demonstrating features of a hypertensive urgency or emergency (e.g., hypertensive encephalopathy, acute coronary syndrome, acute ischemic stroke, intracranial hemorrhage) are diagnosed as hypertensive and treated immediately.
Points to Consider
It is important to note the distinction between elevated blood pressure and a diagnosis of hypertension. Elevated blood pressure refers to an isolated reading, whereby the client has an elevated finding. Hypertension refers to a clinical diagnosis whereby the client has met the criteria for chronic elevated blood pressure. Hypertension will precipitate a treatment protocol, whereas an elevated finding may just require monitoring. See Table 5.3 below for more information on making a determination of hypertension.
Guidelines to Determine Hypertension
Hypertension Canada (Leung, et al., for Hypertension Canada, 2017) states that when assessing chronic high blood pressure, readings must be done under the following conditions:
- No acute anxiety, stress, or pain
- No caffeine, smoking, or nicotine in the preceding 30 minutes
- No use of substances containing adrenergic stimulants such as phenylephrine or pseudoephedrine (may be present in nasal decongestants or ophthalmic drops)
- Bladder and bowel comfortable
- No tight clothing on arm or forearm
- Quiet room with comfortable temperature
- Rest for at least five minutes before measurement
- Ask the client to stay silent prior and during the procedure
Technique Tips
If one of the above conditions is not met, the blood pressure is still taken, but the healthcare provider must take it into consideration. If the blood pressure is elevated, it needs to be repeated to assess the possibility of hypertension.
See Table 5.3 for the guidelines related to management, including monitoring and treatment, in the adult, recommended by Hypertension Canada (Rabi et al., 2020). These recommendations are based on in-office visit one. If manual, the first reading is discarded and the latter two readings are averaged (Rabi et al., 2020). Additionally, multiple readings may be needed when the client has an arrhythmia. As per Hypertension Canada (Rabi et al., 2020), these recommendations are based on:
- High BP as manifest with greater than or equal to manual BP of 140/90 mm Hg or automatic BP of greater than or equal to 135/85 mm Hg (in office).
- High-normal BP as manifest with greater than or equal to manual BP of 130-139/85-89 mm Hg (in office).
Table 5.3: Hypertension Canada Guidelines
| Finding | Management |
|
Visit 1 Office BP Measurements Manual BP averaged reading ≥130–139/85–89 mm Hg (high-normal)
|
Annual follow-up appointments are recommended so that trends and/or increases in blood pressure are assessed. |
|
Visit 1 Office BP Measurements Manual BP averaged reading ≥140/90 mm Hg (high) Automatic BP reading ≥135/85 mm Hg (high) |
A health history and physical examination are performed. Visit two is scheduled within one month of visit one. If clinically indicated, diagnostic tests are scheduled prior to visit two to assess cardiovascular risk factors (see Table 5.4 for modifiable and non-modifiable risk factors) and search for target organ damage (e.g., cerebral vascular, eyes, kidneys, coronary arteries). External, modifiable factors that can increase blood pressure are assessed and removed if possible (certain prescription drugs and other substances like sodium, alcohol, cocaine). Out of office blood pressure measurements (e.g., ambulatory or home blood pressure measurements) are performed before visit two when the automatic BP is 135-179/85-109 mm Hg or the manual BP is 140-179 mm Hg. |
|
Visit 1 Office BP Measurements Automatic or manual BP averaged reading ≥180/110 mm Hg
|
Hypertension is diagnosed and immediate intervention is required. |
The healthcare provider assesses a client’s cardiovascular risk factors for atherosclerosis and hypertension. These risk factors are categorized as modifiable and non-modifiable. See Table 5.4 for an overview of risk factors adapted based on Hypertension Canada guidelines (Leung, et al., for Hypertension Canada, 2017)
Table 5.4: Modifiable and Non-modifiable Risk Factors
| Non-modifiable | Modifiable |
|---|---|
|
|
Test Your Knowledge
Please answer the three questions in the following question set.
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Part of this content was adapted from OER #2 (as noted in brackets above):
© Apr 10, 2017 OpenStax Anatomy and Physiology. Textbook content produced by OpenStax Anatomy and Physiology is licensed under a Creative Commons Attribution License 4.0 license. Download for free at http://cnx.org/contents/7c42370b-c3ad-48ac-9620-d15367b882c6@12
Rabi et al., (2020). Guidelines: Hypertension Canada’s 2020 comprehensive guidelines for the prevention, diagnosis, risk assessment, and treatment of hypertension in adults and children. Canadian Journal of Cardiology, 36, 596-624.
