10 ECG, CO2 Elimination, & ETCO2 Flashcards

1
Q

Einthoven’s Triangle

A

Discovered ECG mechanism

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2
Q

Electrocardiogram

A

Potential difference across the membrane (voltage)

Each cardiomyocyte can create potential difference across the heart

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3
Q

Vector

A

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

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4
Q

Lead I

A
R arm (-) → L arm (+)
0°
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5
Q

Lead II

A
R arm (-) → L leg (+)
60°
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6
Q

Lead III

A
L arm (-) → L leg (+)
120°
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7
Q

Mean Electrical Axis (MEA)

A

Average all depolarization waves = resultant vector

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8
Q

Normal

A

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

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9
Q

Left Axis Deviation

A

-30° to -90°

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

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10
Q

Right Axis Deviation

A

90° to 180°

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

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11
Q

aVR

A
Augmented voltage right
R arm set to positive
Sum L arm + L leg
(-) starting point at chest center
-150°
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12
Q

aVL

A
Augmented voltage left
L arm set to positive
Sum R arm + L leg
(-) starting point at chest center
-30°
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13
Q

aVF

A
Augmented voltage foot
Foot set to positive
Sum R arm + L arm
(-) starting point at chest center
60°
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14
Q

V Leads

A
Transverse plain
V1 = 120°
V2 = 90°
V3 = 75°
V4 = 60°
V5 = 30°
V6 = 0°
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15
Q

Anteroseptal

A

V1

V2

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16
Q

Anteroapical

A

V3

V4

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17
Q

Anterolateral

A

V5

V6

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18
Q

Lateral

A

I, aVL, V5, V6

Left circumflex artery

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19
Q

Inferior

A

Apical
II, III, aVF
R coronary artery

20
Q

Anterior

A

V1 - V4

L anterior descending

21
Q

Beer-Lambert Law

A

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

22
Q

Beer-Lambert Application

A

↑ path-length
↑ absorbance
↓ transmission

23
Q

Absorbance

A

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

24
Q

CO2 Absorber (Scrubber)

A

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

25
Q

CO2 End Products

A

Carbonates (CaCO3)
H2O
Heat

26
Q

Fresh Gas Flow

A

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 $

27
Q

CO2 Absorbent

A
Soda Lime NaOH 
Sodium hydroxide (base)
Base neutralizes volatile acid (CO2)

Calcium Hydroxide Lime
Ca(OH)2
Skips additional step

28
Q

Scrubber Issues

A

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

29
Q

Soda Lime

A
4% NaOH 
80% CaOH2
15% H2O
Large & small irregular granules mixtures
4-8 mesh
Moisture added to prevent drying
Silica added to increase hardness
30
Q

Mesh

A

1/8 inch
1/4 inch
Resistance

31
Q

Chemical Reactions

A

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

32
Q

Indicator Dye

A
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)
33
Q

Calcium Hydroxide

A

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

Ca(OH)2 + CO2 → CaCO3 + H2O

34
Q

Absorbent Canister

A
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
35
Q

INTER-granular Air Space

A

50% total air space

36
Q

INTRA-granular Air Space

A

8-10% total air space

37
Q

Carbon Monoxide

A

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

Desflurane highest CO accumulation

38
Q

Prevent CO Formation

A

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

39
Q

ETCO2

A

End tidal carbon dioxide

40
Q

Incompetent Inspiratory Valve

A

Expired gas sitting in line re-inspired

41
Q

Incompetent Expiratory Valve

A
Pulls in (entrain) gas from expiratory circuit
Expired gas flows back into inspiratory limb and inspired w/ next breath
Baseline CO2 always elevated
42
Q

Abnormal Slope

A

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

43
Q

Capnometry

A

Process to measure CO2 in respiratory gases

Capnometer - device used to measure

44
Q

Capnograph

A

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

45
Q

PaCO2 PETCO2 Difference

A

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

46
Q

ETCO2 Mainstream vs. Sidestream

A

Mainstream - inline measurement
No gas removed

Sidestream - respiratory gas aspiration (disposal)
Adjust volume sampled for pediatric or neonatal patient