Blood pressure

Definition and Measurement of Blood Pressure

  • Blood pressure is the pressure of circulating blood against the walls of blood vessels.
  • It is measured in terms of systolic pressure over diastolic pressure.
  • Blood pressure is usually measured in a brachial artery using a sphygmomanometer.
  • It is expressed in millimeters of mercury or kilopascals.
  • Pulse pressure refers to the difference between systolic and diastolic pressures, while mean arterial pressure is the average pressure during a cardiac cycle.

Importance of Blood Pressure as a Vital Sign

  • Blood pressure is one of the vital signs used by healthcare professionals to evaluate a patient's health.
  • Normal resting blood pressure in adults is approximately 120/80 mmHg.
  • Globally, the average blood pressure has remained relatively stable since 1975.
  • High blood pressure is a risk factor for various diseases, including stroke, heart disease, and kidney failure.
  • Low blood pressure can also have adverse effects on health.

Methods of Blood Pressure Measurement

  • Traditional method: auscultation through a stethoscope using an aneroid gauge or a mercury-tube sphygmomanometer.
  • Semi-automated methods have become common due to concerns about mercury toxicity.
  • Modern devices validated to international standards achieve accurate readings.
  • Most semi-automated methods use oscillometry to measure blood pressure.
  • Ambulatory blood pressure measurement is advocated by some authorities for diagnosing hypertension.

Factors Influencing Blood Pressure

  • Blood pressure is influenced by cardiac output, systemic vascular resistance, blood volume, and arterial stiffness.
  • It varies depending on a person's situation, emotional state, activity, and relative health.
  • Baroreceptors regulate blood pressure in the short term by influencing the nervous and endocrine systems.
  • Hypertension and hypotension can have various causes and may be of sudden or long-term onset.
  • People maintaining lower arterial pressures have better long-term cardiovascular health.

Blood Pressure and Age

  • Fetal blood pressure is primarily regulated by the fetal heart during pregnancy.
  • Blood pressure ranges in children are lower than in adults and depend on height.
  • In aging adults, systolic blood pressure tends to rise from early adulthood onward.
  • Diastolic pressure also rises but starts to fall earlier in mid-life.
  • Pulse pressure increases significantly after the age of 40, attributed to increased arterial stiffness.

Blood pressure Data Sources

Reference URL
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