Chapter 7: Vital Signs
Blood Pressure Ranges
Blood pressure is reported in mm Hg (pronounced millimetres of mercury), in which the systolic is the numerator and diastolic is the denominator. In adults (18 years and older), normal blood pressure typically ranges from 90 to less than 130 mm Hg (systolic) and 60 to less than 80 mm Hg (diastolic). Blood pressure typically rises with age because of the stiffening of arteries and plaque build-up.
The focus of this chapter is adult clients, but it is important to note that like BMI, normative blood pressure ranges in children are based on percentile readings as related to age, sex, and height (Dionne et al., 2017). Generally BP readings greater than the 90th percentile are considered elevated and greater than the 95th percentile are considered hypertension. Here is an example of BP percentiles for:
- female children: link (https://papers.ucalgary.ca/paediatrics//assets/bp-levels—2017-aap-table—girls.pdf).
- male children link (https://papers.ucalgary.ca/paediatrics/assets/bp-levels—2017-aap-table—boys.pdf).
However, a simplified rule of thumb is that a BP of greater than 120/80 mm Hg in those six to 11 years of age and a BP of greater than 130/85 mm Hg in those 12 to 17 years of age should be of concern (Rabi et al., 2020). sider
Points to Consider
In evaluating whether a client’s BP is normal, it is also important to consider the client’s baseline blood pressure and the client’s current health state in conjunction with subjective data and other objective data. For example, a blood pressure of 88/50 mm Hg may be normal for a healthy, asymptomatic 20-year-old adult.
Factors that influence blood pressure include age, sex, ethnicity, weight, exercise, emotions/stress, pregnancy, and diurnal rhythm as well as medication use and disease processes.
- The general pattern is that blood pressure rises with age, so normal variations tend to be higher for older adults.
- Blood pressure is similar in childhood for males and females. After puberty, females have lower blood pressure than males, whereas after menopause females have higher blood pressure than males.
- Research has revealed that ethnicity may be a predictor of blood pressure, but this causation is not necessarily biological, but rather sociocultural. When determining risk for high blood pressure, it is important to consider ethnicity as a contributing factor.
- The diurnal cycle influences blood pressure to be lower in the morning and increase throughout the day until early evening. Try it out: take your blood pressure when you wake up in the morning and then again in late afternoon, and note the difference. This is one reason why healthcare providers document the time a client’s blood pressure is taken.
- Blood pressure can be higher in people who are obese because the heart has to work harder to perfuse the body’s tissues.
- The sympathetic nervous system is stimulated by exercise, stress, anxiety, pain, anger, and fear, which increases blood pressure. Blood pressure returns to baseline within five minutes of rest following activity. Try it out. Have a peer take your blood pressure. Then, run on the spot or do some other cardiac activity for five minutes. Have the peer take your blood pressure again, and then lie down and rest for five minutes. Take the blood pressure again. Note the changes.
- Blood pressure varies throughout the duration of pregnancy. It decreases about halfway through the first trimester until mid-pregnancy due to progesterone effects that relax the walls of blood vessels, causing decreased peripheral vascular resistance. It returns to pre-pregnancy values toward the end of pregnancy.
Points to Consider
White coat syndrome refers to elevated blood pressure due to nervousness or anxiety when clients have their blood pressure taken by a healthcare provider. This occurs in approximately 20% of clients. Key message: have the client take their blood pressure at home with an automatic home blood pressure cuff and compare the findings. Alternatively, you can ask the client to sit quietly and leave the room while an automatic cuff takes a client’s blood pressure. The automatic cuff can be programmed to take three measurements and the blood pressure documented is an average of the three readings.
References
Dionne, J., et al., (2017). Hypertension Canada’s 2017 guidelines for the diagnosis, assessment, prevention, and treatment of pediatric hypertension. Canadian Journal of Cardiology, 33(5), 577-585. http://dx.doi.org/10.1016/j.cjca.2017.03.007
Rabi et al. (2020). 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(5).
Test Your Knowledge
