10 ECG, CO2 Elimination, & ETCO2

Question 1

Einthoven’s Triangle

Answer 1

Discovered ECG mechanism

Question 2

Electrocardiogram

Answer 2

Potential difference across the membrane (voltage)

Each cardiomyocyte can create potential difference across the heart

Question 3

Vector

Answer 3

Mean potential difference
Direction & magnitude
Length correlates to magnitude
(-) → (+)

Question 4

Lead I

Answer 4

R arm (-) → L arm (+)
0°

Question 5

Lead II

Answer 5

R arm (-) → L leg (+)
60°

Question 6

Lead III

Answer 6

L arm (-) → L leg (+)
120°

Question 7

Mean Electrical Axis (MEA)

Answer 7

Average all depolarization waves = resultant vector

Question 8

Normal

Answer 8

-30° to 60° MEA
Lead I positive (upward deflection)
Lead II positive
aVF positive

Question 9

Left Axis Deviation

Answer 9

-30° to -90°

Causes: L ventricular enlargement, R side MI, R side tension pneumo, normal variant (diaphragm elevation

Question 10

Right Axis Deviation

Answer 10

90° to 180°

Causes: R ventricular enlargement, L side MI, L side tension pneumo, pediatrics variant

Question 11

aVR

Answer 11

Augmented voltage right
R arm set to positive
Sum L arm + L leg
(-) starting point at chest center
-150°

Question 12

aVL

Answer 12

Augmented voltage left
L arm set to positive
Sum R arm + L leg
(-) starting point at chest center
-30°

Question 13

aVF

Answer 13

Augmented voltage foot
Foot set to positive
Sum R arm + L arm
(-) starting point at chest center
60°

Question 14

V Leads

Answer 14

Transverse plain
V1 = 120°
V2 = 90°
V3 = 75°
V4 = 60°
V5 = 30°
V6 = 0°

Question 15

Anteroseptal

Answer 15

V1

V2

Question 16

Anteroapical

Answer 16

V3

V4

Question 17

Anterolateral

Answer 17

V5

V6

Question 18

Lateral

Answer 18

I, aVL, V5, V6

Left circumflex artery

Question 19

Inferior

Answer 19

Apical
II, III, aVF
R coronary artery

Question 20

Anterior

Answer 20

V1 - V4

L anterior descending

Question 21

Beer-Lambert Law

Answer 21

Amount energy absorbed or transmitted by solution directly proportional to solution molar absorption and solute concentration
More concentrated solution absorbs more light than more dilute solution

Question 22

Beer-Lambert Application

Answer 22

↑ path-length
↑ absorbance
↓ transmission

Question 23

Absorbance

Answer 23

Measure quantity of light absorbed by sample
Light passes through sample and none absorbed = 0
100% transmission
Therefore solution would be pure solvent

Question 24

CO2 Absorber (Scrubber)

Answer 24

Chemical reaction
Function to remove CO2 from circle system
Neutralization reaction (acid/base)
Able to rebreathe exhaled gas possible

Question 25

CO2 End Products

Answer 25

Carbonates (CaCO3) H2O Heat

Question 26

Fresh Gas Flow

Answer 26

Normal 4.2L/min 0.3-0.5L/min near total rebreathing Complete reliance on absorbent to prevent CO2 rebreathing 4-5/min little to no reliance on absorbent No rebreathing Costly $

Question 27

CO2 Absorbent

Answer 27

``` Soda Lime NaOH Sodium hydroxide (base) Base neutralizes volatile acid (CO2) ``` Calcium Hydroxide Lime Ca(OH)2 Skips additional step

Question 28

Scrubber Issues

Answer 28

Tunneling porous granules line up inside (unable to see) Channeling visible from outside Not enough surface area to scrub the gas to remove CO2 Gas takes the path of least resistance

Question 29

Soda Lime

Answer 29

``` 4% NaOH 80% CaOH2 15% H2O Large & small irregular granules mixtures 4-8 mesh Moisture added to prevent drying Silica added to increase hardness ```

Question 30

Mesh

Answer 30

1/8 inch 1/4 inch Resistance

Question 31

Chemical Reactions

Answer 31

CO2 + H2O → H2CO3 H2CO3 + NaOH → Na2CO3 + H2O + Heat Na2CO3 + Ca(OH)2 → CaCO3 + NaOH

Question 32

Indicator Dye

Answer 32

``` Indicates absorbent function White = ready to go Ethyl violet - purple pH <10.3 used Reverts back to white when not in use (H2O moisture removed) ```

Question 33

Calcium Hydroxide

Answer 33

3rd step in soda lime process 80% Ca(OH)2 1.2% CaSO4 15% H2O Ca(OH)2 + CO2 → CaCO3 + H2O

Question 34

Absorbent Canister

Answer 34

``` 1500ml 1-1.3kg granules Each 100g granules absorbs 15 CO2 Lasts about 8-10hrs assuming total rebreathing and no channeling Air 48-55% total canister volume ```

Question 35

INTER-granular Air Space

Answer 35

50% total air space

Question 36

INTRA-granular Air Space

Answer 36

8-10% total air space

Question 37

Carbon Monoxide

Answer 37

CO can accumulate in absorber Reaction w/ volatile anesthetic and absorbent Carbon monoxide monitors in OR Desflurane highest CO accumulation

Question 38

Prevent CO Formation

Answer 38

Use low gas flow Change absorbent at least weekly Shut off all flow meters when not in use

Question 39

ETCO2

Answer 39

End tidal carbon dioxide

Question 40

Incompetent Inspiratory Valve

Answer 40

Expired gas sitting in line re-inspired

Question 41

Incompetent Expiratory Valve

Answer 41

``` Pulls in (entrain) gas from expiratory circuit Expired gas flows back into inspiratory limb and inspired w/ next breath Baseline CO2 always elevated ```

Question 42

Abnormal Slope

Answer 42

Longer to reach plateau ↑ resistance Problem - obstructive disease or bronchoconstriction

Question 43

Capnometry

Answer 43

Process to measure CO2 in respiratory gases | Capnometer - device used to measure

Question 44

Capnograph

Answer 44

Graph or tracing Anatomical dead space no CO2 or gas exchange Upslope - mixing anatomical & alveolar gas Plateau = max alveolar CO2 (excellent perfusion)

Question 45

PaCO2 PETCO2 Difference

Answer 45

Normal 3-5mmHg d/t mixing & poor perfusion areas Lung disease up to 10mmHg PaCO2 > exhaled CO2 = diffusion & Va problem

Question 46

ETCO2 Mainstream vs. Sidestream

Answer 46

Mainstream - inline measurement No gas removed Sidestream - respiratory gas aspiration (disposal) Adjust volume sampled for pediatric or neonatal patient