Blood Pressure BP

7. Blood Pressure (BP)

  • Blood pressure circulation maintains blood flow throughout the body, regulated by the rhythmic activity of the heart.

  • Valves in the heart and blood vessels direct blood flow, resulting in pulsatile blood pressure that varies between minimum (diastole) and maximum (systole) values.

7.1 Measurement of Blood Pressure

  • Diastolic Blood Pressure (DBP): Minimum pressure during ventricular relaxation ranges from 60-89 Hgmm.

  • Systolic Blood Pressure (SBP): Maximum pressure during ventricular contraction ranges from 100-139 Hgmm.

  • Normal BP measurement units are in millimeters of mercury (Hgmm).

7.2 Blood Pressure Categories

  • Hypotension: SBP < 90, DBP < 60

  • Normal: SBP 90–129, DBP 60-84

  • Prehypertension: SBP 130–139, DBP 85-89

  • Stage 1 Hypertension: SBP 140–159, DBP 90-99

  • Stage 2 Hypertension: SBP 160–179, DBP 100-109

  • Lifestyle changes may be adequate for managing prehypertension, while higher values require medical intervention.

7.3 Variability in Blood Pressure

  • BP can vary as much as 30 Hgmm in a minute.

  • Mean Arterial Pressure (MAP): Calculated as MAP = (SBP + 2*DBP)/3, indicating stable pressure for equivalent blood flow.

  • Pulse Pressure: The difference between SBP and DBP is an important indicator of BP.

  • Averages of multiple measurements provide a more reliable BP assessment than single readings.

7.4 Measurement Techniques

  • Indirect, non-invasive methods are commonly used for BP measurement, offering convenience but reduced accuracy compared to direct methods.

  • White Coat Hypertension: A temporary increase in BP due to stress in medical settings.

  • Sphygmomanometer & Stethoscope: Traditional methods for measuring BP, involving inflation of a cuff to detect the first and second Korotkoff sounds for SBP and DBP, respectively.

  • Automated Devices: Available for everyday use; inflate cuff automatically and provide readings using the auscultatory or oscillometric method.

  • Wrist monitors are available but less reliable than upper arm measurements.

7.5 Advanced Measurement Technology

  • Pulse Plethysmography: Recent introduction in smartwatches, less reliable and requires calibration.

  • Cardiovascular response (HR and BP) shows individual differences during stress; this is known as cardiovascular reactivity, which can be a risk factor for cardiovascular diseases.

  • Individuals often misinterpret their BP, making adherence to treatment challenging, especially for those unaware of their hypertension.