16.1: Introduction to Blood Pressure Measurements
- Page ID
- 125466
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)After completing this lab report, you should be able to:
- Take manual blood pressure measurements.
- Explain why measurements of systolic and diastolic pressure correspond to the first and last sounds of Korotkoff.
- Identify which blood pressure measurements would be considered normal and which are considered hypertension
Blood pressure (measured in mmHg) is generated by the pumping of the heart. Systolic pressure is measured during ventricular systole while the diastolic pressure is measured during ventricular diastole. Blood pressure is measured indirectly with a sphygmomanometer (blood pressure cuff) and a stethoscope. The sphygmomanometer includes an inflatable cuff connected to a pump and a pressure gauge. The cuff is wrapped around the arm at the level of the heart and inflated to a pressure above the systolic pressure to occlude the brachial artery. While the pressure in the cuff is released gradually, the examiner uses a stethoscope to listen to the sounds of Korotkoff created by the noisy blood flow through the narrow blood vessel. The sound of Korotkoff will continue until the pressure in the cuff opens the artery completely and the blood flows quietly. The first sound heard is the systolic pressure while the last sound heard is the diastolic pressure. For example, a typical blood pressure measurement of 120/80 represents a systolic pressure of 120 mmHg and a diastolic pressure of 80 mmHg.
Blood pressure measurements are typically taken with the subject sitting down and their arm at heart level, resting on a table or other support. Not supporting the arm or having the arm below heart level can lead to inaccurate blood pressure measurements. For example, when standing, with the arm hanging by the side, blood pressure in the arm will be higher than when seated with the arm supported at heart level. This is due to the effect of gravity and blood pressure compensating for this effect.
Clinical Relevance
A normal blood pressure measurement for a given individual depends on the person’s age, sex, genetics, and environment. Considering these factors, chronically elevated blood pressure measurements may indicate an unhealthy state called hypertension, a major risk factor in heart disease and stroke. Hypertension may be divided into two general categories. Primary hypertension (95% of all cases) refers to hypertension of unidentified cause. Secondary hypertension refers to hypertension that is due to a known medical condition or disease.
| Blood Pressure Classification | Systolic Blood Pressure | Diastolic Blood Pressure | |
| Normal |
≤120 mmHg |
and | ≤80 mmgHg |
| Pre-hypertension | 130-139 mmHg | or | 81-89 mmHg |
| Stage 1 hypertension | 140-159 mmHg | or | 90-99 mmHg |
| Stage 2 hypertension | 160 mmHg or greater | or | 100 mmHg or greater |