Important Concepts Associated with the Measurement of Blood Pressure

BP is one of the principal vital signs

BP Classification Systolic/Diastolic Values Normal 119/79 or less Prehypertension 120/80 to 139/89 Stage 1 Hypertension 140/90 to 159/99 Stage 2 Hypertension 160/100 or higher Classification of hypertension (elevated blood pressure) in adults Classification of hypertension (elevated blood pressure) in adults

Atrioventricular valves Aortic and pulmonary valves Open Closed Open ESV Electrocardiogram Left heart P 1st2nd QRS P Heart sounds Atrial systole Dicrotic notch Left ventricle Left atrium EDV SV Aorta T Ventricular volume (ml) Pressure (mm Hg) Ventricular SYSTOLE Atrial SYSTOLE Ventricular DIASTOLE “Lup” = closing of L AV valve or Mitral valve (1 st heart sound) “Dup” = closing of Aortic valve (2 nd heart sound) EDV = End Diastolic Volume ESV = End Systolic Volume SV = Stroke Volume Blood Pressure (BP) when measured with a sphygmomanometer mostly closely approximates aortic pressure. Review of aortic pressure:

Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery Posterior tibial artery Dorsalis pedis artery Superficial temporal artery Facial artery More practically, blood pressure (BP) is a measure of pressure in the brachial artery (a vessel located a small distance from the aorta). The dots here represent pressure points located throughout the body.

Blood Pressure (BP) Force exerted by circulating blood on the walls of the brachial artery (if measured traditionally)

Force exerted against walls of a blood vessel when the heart contracts (systole) Systolic Blood Pressure

Force exerted against walls of a blood vessel when the heart relaxes (diastole) Diastolic Blood Pressure

Average blood pressure or mean arterial pressure (MAP) is determined by obtaining both systolic and diastolic values of the blood vessel. (point of this exercise)

Where does your blood pressure fall? And YOU think you have stress!

Atrioventricular valves Aortic and pulmonary valves Open Closed Open ESV Electrocardiogram Left heart P 1st2nd QRS P Heart sounds Atrial systole Dicrotic notch Left ventricle Left atrium EDV SV Aorta T Ventricular volume (ml) Pressure (mm Hg) Ventricular SYSTOLE Ventricular DIASTOLE “Lup” = closing of L AV valve or Mitral valve (1 st heart sound) “Dup” = closing of Aortic valve (2 nd heart sound) EDV = End Diastolic Volume ESV = End Systolic Volume SV = Stroke Volume Cardiac Output can be calculated with a quick and easy mathematical formula (using the above information). Other concepts to review:

Stroke Volume (SV) Volume of blood pumped out by a ventricle with each heart beat

Heart Rate (HR) Number of beats per minute

Graph showing the change in volume (mL) of blood in one “chamber” during a heart beat What is the volume of blood at the end of diastole? diastole systole EDV

Graph showing the change in volume (mL) of blood during one heart beat What is the volume of blood at the end of systole? ESV diastole systole

Graph showing the change in volume (mL) of blood during one heart beat Therefore, what is the stroke volume? SV diastole systole

Cardiac Output (CO) Volume of blood (mL) pumped by each ventricle in one minute (min)

Cardiac Output (CO) is Heart Rate (HR) x Stroke Volume (SV)

Example: What would be the cardiac output of an individual at rest (60 beats/min) and with no obvious heart condition (use the stroke volume already given)? Answer: CO (mL/min) = HR (60 beats/min)  SV (70 mL/beat) = 4,200 mL/min or 4.20 L/min

This means that over the course of one hour, one heart chamber at rest could eject over 240 liters of blood. That’s over 63 gallons! Sixty-three gallons for a little over six and a half days … this could fill a 10,000 gallon (small size) swimming pool. With continuous exercise (120 beats per minute), that time could be cut in half (about 3 days)! * 1 Liter = US Gallons

Measuring Blood Pressure (BP) Interactive Physiology Exercise (In order to make this work, an access code log-in is required.) Steps: Click on Tutorials > Interactive Physiology > Chapter 19 > Cardiovascular System > Measuring Blood Pressure (The plan here will be to complete all steps and the quizzes/worksheets in lab class.) Click below if you have a username & password at MyA&Pplace.com