Practicals

Question 1

What does the P wave signify?

Answer 1

Atrial depolarization

Question 2

What does the PR interval signifiy?

Answer 2

AV nodal delay

Question 3

What does the QRS complex signify?

Answer 3

Ventricular depolarization

(simultaneous atria repolarization)

Question 4

What does the ST segment signify?

Answer 4

Ventricles contracting and emptying

Question 5

What does the T wave signify?

Answer 5

Ventricular repolarization

Question 6

What does the QT interval signify?

Answer 6

Ventricular depolarization and repolarization

Question 7

What does the TP interval signify?

Answer 7

Ventricle relaxing and filling

Question 8

How to calculate HR from ECG tracing?

Answer 8

100 / number of big squares in an RR interval

Each small square = 0.04sec

60 / (0.04seconds * small squares) = bpm

Question 9

Describe the BIPOLAR limb leads degrees and ECG signals

Answer 9

Lead I = left to right arm (0)
Lead II = left arm to ankle (60)
Lead III = right arm to ankle (120)

All positive deflections
Lead II has the largest positive spike

Question 10

Describe the UNIPOLAR limb leads degrees and ECG signals ***

Answer 10

aVL = BIPHASIC or ISOMETRIC line 30
aVF = Positive 90
aVR = Negative 150

The reference point is the heart
So think about the direction depolarization occurs

Right foot is grounding electrode = doesn’t measure anything

Question 11

What is the normal range of QRS axis?

Answer 11

-30 to +90 degrees

Question 12

What can QRS axis deviation diagnose?

Answer 12

Right Axis Deviation (RAD) occurs when the QRS axis is more than +90° or toward the right side of the heart. This deviation can be seen in conditions where the right side of the heart is working harder, causing it to become enlarged or overactive.

Left Axis Deviation (LAD) happens when the QRS axis shifts to less than -30°. This indicates that the electrical activity is moving more toward the left side of the heart.
LAD suggests that the left ventricle is under strain or there is a blockage in the conduction system, changing the direction of electrical impulses

Question 13

What are causes of right axis deviation?

Answer 13

RV hypertrophy
Chronic lung disease
Pulmonary embolism (blockage)

Question 14

What are causes of left axis deviation?

Answer 14

LV hypertrophy
Conduction abnormalities
Inferior myocardial infarction

Question 15

What two leads express a QRS that is 0 degrees and +90 degrees?

Answer 15

Lead I = 0 degrees (moving RIGHT)

aVF = +90 degrees (moving DOWN)

Question 16

What heart conditions can we see in ECG?

Answer 16

Atrial Premature Beat
Tachycardia
Ventricualr fibrilliaton
Myocardial infarction (STEMI)

Question 17

Where is V1 chest lead placed?

Answer 17

4th intercostal space on the right side of the sternum

Question 18

Where is V2 chest lead placed?

Answer 18

4th intercostal space on the left side of sternum

Question 19

Where is V3 chest lead placed?

Answer 19

Between V2 & V4

Question 20

Where is V4 chest lead placed?

Answer 20

Mid-clavicular 5th intercostal space

Question 21

Where is V5 chest lead placed?

Answer 21

Anterior axillary 5th intercostal space

Question 22

Where is V6 chest lead placed?

Answer 22

Mid-axillary 5th intercostal space

Question 23

To measure blood pressure, what arteries do we look at?

Answer 23

Brachial artery
Radial artery

Question 24

What sounds are we listening for?

Answer 24

Korotkoff sounds

Question 25

When will and won't we hear Korotkoff sounds?

Answer 25

When artery is fully compressed and there is no blood flow = no sound Compressed artery to increase velocity of blood = creates vibrations heard as Korotkoff sounds Flow is uncompressed = no sound

Question 26

So when do we take note of blodo pressure?

Answer 26

When you first hear Korotkoff sounds = systolic bp When Kototkoff sounds stop = diasolic bp

Question 27

How do we estimate systolic pressure?

Answer 27

Inflate cuff until radial pulse disappears

Question 28

How do we measure blood pressure manually?

Answer 28

Place stethoscope over brachial artery Inflate cuff to 10-20 mmHg above ESTIMATED systolic bp Slowly deflate cuff Listen for Krortkoff sound = systolic bp Listen until sound disappears = diastolic bp

Question 29

What happens to bp when we stand from lying down?

Question 30

What is direct calorimetry?

Answer 30

Measuring energy expenditure by capturing heat produced by the body in calories

Question 31

What is heat?

Answer 31

Byproduct of metabolic processes 60% of energy from glucose/fat metabolism

Question 32

What is indirect calorimetry?

Answer 32

Estimates energy expenditure by measuring RER RER = respiratory exchange ratio

Question 33

What does RER stand for?

Answer 33

respiratory exchange ratio

Question 34

How is RER measured?

Answer 34

Volume of O2 consumed (VO2) Volume of CO2 produced (VCO2)

Question 35

What are some application of indirect calorimetry?

Answer 35

Estimate energy expenditure Evaluate substrate utilization Assess aerobic fitness Clinical applications

Question 36

How are VO2 and VCO2 measured? What is the equation?

Answer 36

VO2 = (fraction of inspired O2 x INSPIRED volume) - (fraction of expired oxygen x EXPIRED volume) Same for VCO2

Question 37

How is fraction of INSPIRED O2 measured?

Answer 37

20.93% ~ 21% at sea level

Question 38

How is fraction of EXPIRED O2/CO2 measured?

Answer 38

Measured by gas analyzer

Question 39

How is inspired volume of O2/CO2 measured?

Answer 39

Assumed equal to EXPIRED air

Question 40

How is expired volume of O2/CO2 measured?

Answer 40

Measure by flow meter

Question 41

Describe the different substrates

Answer 41

Fatty acids = almost unlimited but slower source of energy Carbohydrate = relatively limited by more efficient source of energy

Question 42

What happens to substrate utilization as exercise intensity increases and why?

Answer 42

Swaps from using fats more to using carbohydrates more Carbs = more EFFICIENT source of energy 5.05 kcal/L of oxygen

Question 43

How to calculate RER and what it tells us

Answer 43

VCO2 / O2 If RER is nearer 0.7 = fatty acids If RER is nearer 1 = carbohydrates

Question 44

How do we calculate energy expenditure per min?

Answer 44

Energy correlated to RER x VCO2 = how many kcal expended in 1minute

Question 45

Why do we need to calibrate the indirect calorimetry tools?

Answer 45

Because need to correlate it to SEA LEVEL and TEMPERATURE in the room