Blood Pressure

Dino MagouNew Jersey Institute of TechnologyMaterials Science and Engineering

Biomedical Engineering

Friday night?

Vital Signs

• Physiological measurements taken to quickly understand a patient’s basic body functions

• There are four basic vital signs– Temperature

– Pulse

– Blood Pressure

– Respiratory rate

Blood Pressure

• Pressure that circulating blood creates against the walls of blood vessels

• Usually taken inside the elbow at the brachial artery

• Blood pressure is reported in mmHg

• Blood pressure readings can be used to diagnose health problems

Stethoscope and Sphygmomanometer

• Used to measure blood pressure

• Operator listens to patient’s pulse while tightening the BP cuff

• When pulse can no longer be heard, pressure is released– Pressure is recorded

Diastolic and Systolic

Pumping

Resting

MAP

• MAP - Mean Arterial Pressure–Mean = Average

• Used to describe the average blood pressure in a person

• Not a simple average– Time the heart rests (diastole) is 2 times longer

than the time the heart pumps (systole)

• Normal MAP is ~ 60 mmHg

How does MAP relate to a person’s physiologic condition?

• Paramedics monitor MAP closely in patients who have suffered from sever blood loss

• Low MAP means not enough blood to vital organs

• Lack of blood affects supply of O2

– Commonly called Ischemia

• Ischemia leads to permanent organ damage/failure

How does caffeine affect your BP?

Before coffee After 3 cups of coffee

Experiment 1: Blood pressure and Temperature

• Take normal blood pressure

• Take blood pressure while having hand in bath of ice for 15 seconds

• Compare both blood pressures

• What do you think will happen?

Why did that happen?

• The cold caused discomfort, maybe even pain

• Symptoms like discomfort activate the sympathetic nervous system– “Fight or flight” response

• Zebra grazing grass

• Heart rate is increased by constraining blood vessels– This increases systolic,

diastolic and MAP

Blood Supply

• Your body needs constant pressure to supply: –Muscles with enough O2 to function

– Effectively remove waste products (eg. CO2)

• Remember: Mean arterial pressure can be used to diagnose how much blood is effectively getting to your organs

• How should exercise affect blood pressure?

Experiment 2: Blood Pressure and Exercise

• Take normal blood pressure

• Take blood pressure after having run in place for 2 minutes

• Compare both blood pressures

• What should we see?

What did your body do?

• During exercise your muscles need more blood to function properly– Blood delivers O2, and removes CO2

• In order to get that extra blood to your muscles, your heart pump faster (higher pulse) and actually increases the amount of blood per pump– This increases systolic pressure

– Diastolic pressure should decrease or remain the same

Me at the gym…

Before run After 1 mile run

Why is BP important to you?

What happens to your heart

• Heart enlarges and weakens

• High pressure can damage delicate organs– eg. Eye

• High risk of heart attack and stroke

• Permanent damage – Loss of limbs and or basic

functions

How to keep it healthy

• Don’t smoke

• Maintain healthy weight

• Exercise REGULARLY

• Keep healthy diet – Avoid excessive sodium, fat

and cholesterol

Age and BP

Recap

• Blood Pressure – how hard your heart works– Systolic (pumping)

– Diastolic (resting)

• Diet and exercise affect your Blood Pressure– Caffeine, fatty and greasy foods

• Temperature and environmental stimulus affects BP– “Fight or flight” response