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