Heart rate and blood pressure

Cardiac Cycle (heart beat)

• Systole (Ventricles contract - Expel Blood)

• Diastole (Ventricles relax - Filling)

Heart Rate

• Frequency of Cardiac Cycle measured in Beats Per Minute (BPM)

Measuring Heart Rate

Electrocardiogram (ECG)

• “Gold Standard”

Auscultation

• Listening to heart beat (e.g. Stethoscope)

• 3rd intercostal space, left of sternum

Palpation

• Feeling heart beat

• Brachial, Carotid, Radial, and Temporal arteries

Auscultation

1. Insert ear tips in ears so the tips point forward/down

2. Gently tap the diaphragm to test for sound

3. Position the stethoscope just below the left pectoralis major muscle firmly against the skin

   • 3rd intercostal space, left of sternu,

4. Start counting

HR Palpation Technique

• Use tips of index and middle fingers (thumb have a pulse)

• Apply light pressure to find a string pulse

• Don;t be afraid to move around

• Start stopwatch sumultaneously with pulse beat

• Count the number of beats you hear / feel

  • 1st beat is zero

• Heart Rate = # of beats counted in 20 seconds x 3

Resting Heart Rate

• Heart Rate when you are at complete rest

• Not Always, indicative of cardiorespiratory fitness

• Measure for 30 sec x 2

Classification

• Bradycardia (<60 bpm)

• Normal (60-100 bpm)

• Tachycardia (>100 bpm)

Exercising Heart Rate

Steady-state HR – after about 3 min, a difference in HR of no more than 5 bpm during a 1 min. period

Measured via radial pulse palpation, auscultation with a stethoscope, or the use of HR monitors.

• Radial pulse is most typical for palpation; Duration = 10 seconds

Post-Exercise

• Hr can drop rapidly following exercise, begin timing pulse counts as quickly as possible

• Average of 2-3 measures fro greater accuracy

Recovery Heart Rate

May take up to 30 minutes for HR to return to RHR

What is the minimum amount of time needed for a cool down?

◦ Minimum of 3 minutes cool down (~110 BPM)

◦ BEST is 1 minute at 85% intensity, 1 minute at 65% , 1 minute at 45%

The rate of reduction is associated with CVD risk

• Less than 12 BPM reduction (at 1 Minute) = Increased risk for CVD

• More than 50 BPM reduction (at 1 Minute) = Reduced risk for CVD

• Also guides progress and can help identify overheating or dehydration (viscosity)

Maximal Heart Rate

• The highest heart rate value attainable during an all-out effort to the point of exhaustion.

• Age related decline may range from 3 – 7%

• Disease and sedentary behavior increase the speed of decline

Determing Maximal Heart Rate

Direct Measurement

Measuring heart reate during maximal effort (typically during maximal exercise test)

Indirect Measurement

Prediction Equations

• Fox and Haskell (1971): HRmax = 220 - Age

• Inbar (1994): 205.8-[0.685 x Age]

• Tanake et al. (2001): Hrmax =208-[0.7 x Age]

• Nes (2012): 211 - 0.64 x Age

Cardiac Output - CO or Q

• is the total amount of blood pumped by the heart per minute

• CO and blood Pressure are also related

  • An increase in CO will result in an increase in BP

Typical Values

Males: 5.6 L/min

Females: 4.9 L/min

CO =SV x HR

Stroke Volume

The volume of blood pumped out of the left ventricle of the heart in one heart beat.

◦ Typical Value = 70 ml; 55 – 100 ml

Determinants

• Gender (Men > Women)

• Heart Size

• Training Status C

• ontractility of heart

• Duration of Contraction

  • ◦ (normal = 0.8 seconds)

Pulse Pressure

• Tells us about vascular compliance

• Measures stress exerted on small arteries affecting nutrient exchange

• Correlation with Heart Function (see Stroke Volume and Cardiac Output)

PP = Systolic Blood Pressure - Diastolic Blood Pressure

Rate Pressure Product

Refers to the ability of the heart to provide blood (and oxygen) to itself

RPP = HR x Systolic Pressure

• Highly correlated to O₂ consumption by heart

• Improvement > Improved VO2 max

Mean Arterial Pressure

A useful concept because it can be usued to calculate overall blood flow

Average blood pressure or average arterial pressure during a single cardiac cycle

Estimation = DBP + 1/3 (SBP-DBP)

Points of Interest

Normal (77-97 mmHg)

Varies by location

Standing Person: Head = 62; Ankle = 180

Influences occurrence of Edema, Fainting, Athreosclerosis, Kidney Failure, and Aneursym

Measuring Blood Pressure

Sphygmomanometer

Gauge graduated in millimeters of mercury (mm Hg) attached to an inflatable cuff

Cuff is wrapped around the upper arm 1” above antecubital fossa and inflated to a pressure that will shut off the brachial artery.

Stethoscope used to listen to the sounds of blood flow in the brachial artery (1 cm superior and medial of the antecubital fossa)

Blood Pressure Reading

Systolic

Pressure on arterial wall when blood is being pumped from the left Diastolic

Pressure on arterial wall when the heart is at rest

The unit for expressing BP is mm Hg referring to the Mercury (Hg) used to measure BP in a sphygmomanometer

Inflating Cuff

Cuff should be inflated ~20 – 30mmHg over estimated SBP (1st Korotkoff sound)

….200 is always a safe bet with clinical populations

Estimating SBP

Use previous measurement

◦ During exercise, keep in mind that SBP increases

Palpate radial artery while inflating cuff

◦ SBP when pulse disappears

◦ Obtain estimate of SBP by palpating radial artery while inflating cuff.

◦ DBP is estimated by subsequently decreasing pressure by 2-3 mm Hg · s −1 and noting when the pulse reappears

BP Assessment procedures

1. Patients should be seated quietly for at least 5 min in a chair with back support (rather than on an examination table) with their feet on the floor and their arms supported at heart level. Patients should refrain from smoking cigarettes or ingesting caffeine for at least 30 min preceding the measurement.

2. Measuring supine and standing values may be indicated under special circumstances.

3. Wrap cuff firmly around upper arm at heart level; align cuff with brachial artery.

4. The appropriate cuff size must be used to ensure accurate measurement. The bladder within the cuff should encircle at least 80% of the upper arm. Many adults require a large adult cuff.

5. Place stethoscope chest piece below the antecubital space over the brachial artery.

6. Quickly inflate cuff pressure to 20-30 mm Hg above the estimated SBP previously determined via palpation

7. Slowly release pressure at rate equal to 2–3 mm Hg · s −1 .

8. SBP is the point at which the first “thud” or the Korotkoff sound is heard (phase 1), and DBP is the point before the disappearance of Korotkoff sounds (phase 5).

9. At least two measurements should be made (minimum of 1 min apart) and the average should be taken.

10. BP should be measured in both arms during the first examination. Higher pressure should be used when there is consistent interarm differences.

11. Provide to patients, verbally and in writing, their specific BP numbers and BP goals.

Measuring Exercise BP

Client should not grasp handlebars or handrails.

Have tubing protruding from bladder superior instead of inferior.

Stabilize client’s arm between your arm and trunk.

Position manometer at eye level.

Inflate cuff well above anticipated value.

Potential Sources of Error

1. Technician (Inexperience, auditory acuity, reaction time)

2. Faulty Equipment (Inaccurate Sphygmomanometer, Improper Cuff size)

3. Procedural Errors (Rate of inflation/deflation, Sphygmomanometer/Stethoscope placement, Allowing patient to hold something/flex elbow)

4. External Distractions (i.e. Background noise)

5. Certain physiologic abnormalities (e.g. damaged brachial artery, subclavian steal syndrome, arteriovenous fistula)

6. Client not properly positioned or gripping an item