Physics- Monitors

Front 1

Who invented the EKG, and when?

Back 1

William Einthoven, 1924

Front 2

Einthoven's contribution to ECG-recording technology was the development and application of the ______ which recorded very small elctrical currents produced by the human heart.

Back 2

string galvanometer

Front 3

The string galvanometer produced a very long filament of _________ that conducted the electrical currents from the heart. This filament was acted upon by powerful _________, which caused the sideways displacement of the filament in proportion to the current carried.

Back 3

negligible mass,
electromagnets

Front 4

In the string galvanometer, the movement of the filament was measured using sensitive ______.

Back 4

optical devices

Front 5

Filaments were coated in ____ to provide the conductive pathway for the current.

Back 5

silver

Front 6

The original string galvanometer machine required _____ for the powerful electromagnets, required ___ operators, and weighed ____ lbs.

Back 6

water cooling, 5 operators, 600 lbs

Front 7

The ECG recording is obtained by making the string opaque with a coat of ____, placing it in a beam of light which throws a vertical _____, magnified by a microscope, onto a metal plate in which there is a horizontal slot. This slow allows only a point of shadow to pass through a moving _______ plate or film, on which the point of shadow writes in a continuous curve.

Back 7

silver, shadow, photographic

Front 8

The first string galvanometer required the patient to submerge their ____ and ____ in a tub of ______.

Back 8

arm and leg, salt solution

Front 9

The 3 lead EKG gives a _____ degree orientation of the heart.

Back 9

120

Front 10

The electrode placement made it possible to achieve a low contact _______ and maximize the EKG signal and the electrode location is unmistakably defined.

Back 10

impedence

Front 11

The lead vectors associated with Einthoven's lead system are conventionally found based on the assumption that the heart is located in or at the center of a _______ representing the torso.

Back 11

homogenous sphere

Front 12

If the positon of the right arm, left arm, and left leg are the vertices of an equilateral triangle, having the heart located at its center, then the lead vectors also form a ______.

Back 12

equilateral triangle

Front 13

A simple model results from assuming that the cardiac sources are represented by a _____ located at the center of the sphere representing the torso, hence at the center of the equilateral triangle.

Back 13

dipole

Front 14

With these assumptions, the _____ measured by the 3 limb leads are proportional to the projections of the ______ on the sides of the lead vector triangle.

Back 14

electric heart vector

Front 15

Lead I goes from ____ to ___.
Lead II goes from ___ to ___.
Lead III goes from ____ to ___.

Back 15

I: RA to LA
II: RA to LL
III: LA to LL

Front 16

Lead I is at the angle of ____, Lead II is at the angle of ____, Lead III is at the angle of ____.

Back 16

I: 0 degrees
II: 60 degrees
III: 120 degrees

Front 17

AVL

Back 17

lateral left view of LV, points from center to L shoulder

Front 18

AvF

Back 18

inferior view, points from center to groin

Front 19

AvR

Back 19

right view, points from center to R shoulder, abnormal in CHF

Front 20

What are the angles associated with V1 through V6?

Back 20

V1 120 degrees
V2 90
V3 75
V4 60
V5 30
V6 0

Front 21

The precordial views make up a cross sectional view of the heart in a _______ plane projecting a view across the _____.

Back 21

transverse horizontal, AV node

Front 22

Which are the lateral leads?

Back 22

I, aVL, V5, V6

Front 23

Which are the inferior leads?

Back 23

II, III, and aVF

Front 24

Which are the anterior leads?

Back 24

V1, V2, V3, V4

Front 25

What coronary artery is supplied by the inferior leads (II, III, aVF)?

Back 25

RCA

Front 26

What coronary artery is supplied by the anterior leads (V2-V5)?

Back 26

LAD

Front 27

What coronary artery is supplied by the lateral leads (I, aVL, V4-V6)?

Back 27

Left circumflex

Front 28

Axis deviations are commonly caused by...

Back 28

obesity

Front 29

What are the normal EKG changes with axis deviation?

Back 29

Positive in Leads I, avF/II

Front 30

What are left axis deviation changes and what does it suggest?

Back 30

Positive in lead I and
Negative in Lead aVF/II

normal variant for diaphragm elevation
LV enlargement, Inferior MI, R sided tension pneumothorax

Front 31

What are the right axis deviation changes and what does it suggest?

Back 31

Negative in lead I and
Positive in Lead aVF/II

normal variant in children
RV enlargement, Lateral MI, left sided tension pneumothorax

Front 32

What is the function of the CO2 absorber?

Back 32

removal of CO2 from the circle system, makes rebreathing of exhaled gas possible

Front 33

What is the principle of the CO2 absorber?

Back 33

neutralization reaction between an acid and base

Front 34

What are the endproducts of CO2 absorbers?

Back 34

carbonates, H20, heat

Front 35

What determines the amount of rebreathing in the circle system?

Back 35

gas flow through flowmeters

Front 36

How much rebreathing is going on when FGF is 0.3-0.5 lpm?

Back 36

near total rebreathing, complete reliance on absorbent to prevent rebreath

Front 37

How much rebreathing is going on when FGF >/= volume exhaled (> 4-5 lpm)?

Back 37

little to no reliance on absorbent

Front 38

At what gas flows does absorbent last longer?

Back 38

low flows- does not last long
high flows- blowing off all the CO2, absorbent lasts longer

Front 39

What are some things to consider/assess for if ETCO2 is rising?

Back 39

- check to se if absorbent is exhausted and has color change
- assess for hypoventilation
- MH (first symptom, CO2 rises from 30s to 60s rapidly)

Front 40

CO2 absorbent is a mixture of _____ that is (acidic/basic) in nature.

Back 40

porous irregular granules (smaller and larger), basic

Front 41

What are the 2 types of CO2 absorbent?

Back 41

NaOH (soda lime)
BaOH (baralyme)

Front 42

What is the mesh size in CO2 absorbent?

Back 42

4:8 mesh (1/8 to 1/4 inch)

Front 43

What are the components of soda lime?

Back 43

- 4% NaOH
- 1% KOH
- 76-81% CaOH
- 14-19% H20

Front 44

Why are moisture and silica added to soda lime?

Back 44

- moisture: water to prevent drying
- silica: added to incr hardness

Front 45

Baralyme does not require _____, and is much ______, used in third world countries.

Back 45

silica, cheaper

Front 46

What are the components of bara lyme?

Back 46

- 20% BaOH
- 80% CaOH
- H20 is chemically bound to the BaOH with crystallization

Front 47

Bara Lyme is less likely to _____ and is slightly ______ than soda lime.

Back 47

dry out, harder

Front 48

In soda lime, CO2 + H2O -->

Back 48

H2CO3

Front 49

In soda lime, H2CO3 + NaOH -->

Back 49

Na2CO3 + H2O + Heat

Front 50

In soda lime, H2CO3 + KOH -->

Back 50

K2CO3 + H20 + heat

Front 51

In soda lime, Na2CO3 + Ca(OH)2 -->

Back 51

CaCO3 + NaOH

Front 52

In soda lime, K2CO3 + Ca(OH)2 -->

Back 52

CaCO3 + KOH

Front 53

H2CO3

Back 53

carbonic acid

Front 54

Na2CO3

Back 54

sodium carbonate

Front 55

K2CO3

Back 55

Potassium carbonate

Front 56

Ca(OH)2

Back 56

calcium hydroxide

Front 57

Describe the indicator dye in CO2 absorbent

Back 57

- organic dye
- physical indicator of absorbent function
- ethyl violet (turns purple when pH < 10.3, reverts to white when not in use)

Front 58

Each CO2 absorbent cannister contains _____mL with ____ kg of granules.

Back 58

1500 mL, 1-1.3 kg

Front 59

Each 100 g of granules absorbs ____ liters CO2

Back 59

15

Front 60

What is the mean adult anesthetized CO2 production?

Back 60

12-18 L/hr (avg 15 L/hr)

Front 61

Each CO2 absorbent cannister lasts about _____ hours, assuming total rebreathing and no channeling.

Back 61

8-10

Front 62

Cannister air space consumes ____% of total cannister volume.

Back 62

48-55%

Front 63

What are the 2 types of CO2 absorbent air space?

Back 63

- INTERgranular: 50% of total air space
- INTRAgranular: 8-10% of total air space

Front 64

Soda and Bara lyme degrade ______.

Back 64

volatile anesthetics

Front 65

4 times as much ____ breaks down in baralyme, forming ______ Which causes renal toxicity. Therefore, you must use at least ____ FGF.

Back 65

sevoflurane, Compound A, 2 lpm

Front 66

What can accumulate in teh absorbent as a byproduct of the reaction between volatile anesthetic and absorbent?

Back 66

CO

Front 67

Which IA has the highest accumulation of CO in the absorbent?

Back 67

desflurane

Front 68

Beer Lambert Law

Back 68

- measurement of light absorbence to determine the concentration of a solute in a solution, used to measure ETCO2 and SPO2
- intensity of light falls exponentially as it passes through a liquid

Front 69

With increasing frequency, energy waves become _____, and visible light disappears between ____ and ____ Rays.

Back 69

shorter, infrared and UV

Front 70

What are the highest and lowest frequence energy waves?

Back 70

highest- gamma
lowest- radio

Front 71

What is the difference between a capnometer and a capnograph?

Back 71

capnometer is the color changer on the ambu bag, capnograph is the picture on the monitor of the CO2 waveform

Front 72

capnometry

Back 72

measurement of CO2 in respiratory gases

Front 73

What is the difference between mainstream vs sidestream?

Back 73

mainstream: in-line measurement/ no gas removed
sidestream: aspiration of resp gas/ disposal

Front 74

What are the 3 measurement techniques for ETCO2 measurement?

Back 74

1. infrared light absorption (CO2 strongly absorbs infrared light)
2. mass spectrometry
3. raman spectroscopy

Front 75

During what phase in the ETCO2 waveform do inspiration and expiration occur?

Back 75

inspiration: phase I
expiration: phase III, alveolar plateau

Front 76

At what part in the ETCO2 waveform is ETCO2 measured?

Back 76

at the end of alveolar plateau in phase III - ETCO2max is highest level achieved during expiratory phase

Front 77

What does it indicate if the baseline phase I of your ETCO2 waveform is higher than 0?

Back 77

may indicate MH, CO2 is so high that you're never getting to a zero baseline, very hypercarbic

Front 78

What is the difference between PaCO2 and PetCO2max in patients with and without significant lung disease?

Back 78

without lung disease: PaCO2-PetCO2max differ by 3-5 mmHg
with lung disease: PaCO2-PetCO2max can be as large as 10 mmHg

Front 79

What is the relationship betwen PetCO2max and PaCO2?

Back 79

etCO2 high = paCO2 high
etCO2 normal = paCO2 normal or high
etCO2 low= PaCO2 low/normal/high

Front 80

What is the #1 reason for an elevated baseline etCO2 reading?

Back 80

failure to calibrate the machine

Front 81

Pulse oximetry is a noninvasive estimate of _____, directly related to ____ content of arterial blood.

Back 81

SaO2, O2

Front 82

What does a pulse ox actually measure?

Back 82

- estimate arterial O2 saturation using the ratio of O2Hgb of TOTAL Hgb (O2Hgb + RHgb)
- determines the ratio using variations in light absorption in 2 different wavelengths

Front 83

Describe the difference between light absorption between O2Hgb and RHgb?

Back 83

- O2Hgb absorbs light at 940 nm (invisible/infrared)
- RHgb absorbs light at 660 nm (visible/red)

Front 84

What is methemoglobin?

Back 84

normally, <1% of the total Hgb, an oxidation product of Hgb that forms a reversible complex w oxygen and impairs the unloading of O2 into tissue

Front 85

How do SPO2 monitors read MetHgb, and why is this a problem?

Back 85

- metHb absorbs light equally at the red and infrared wavelengths -- most pulse ox's will give a false LOW reading for spo2 > 85% and a false HIGH value for Spo2 < 85% -- must use ABG for definitive diagnosis, just reads 85% all the time!

Front 86

What drugs can cause MetHgb?

Back 86

- nitrobenzene (hurricane spray)
- benzocaine
- prilocaine
- dapsone

Front 87

How is functional SPO2 calculated?

Back 87

SpO2 = ( O2Hgb /
[O2Hgb + Hgb] ) x 100

Front 88

How is fractional Spo2 calculated?

Back 88

Spo2 = [(O2Hgb) /
( O2Hgb + Hgb + metHgb + COHgb)] x 100

Front 89

What 2 unoxygenated variants of Hgb can cause false spo2 readings?

Back 89

COHgb and MetHgb

Front 90

In Spo2 measurement, light absorbance occurs due to the _____ of arterial blood.

Back 90

pulse added volume

pulsations caused by systolic expansion of the vascular bed produces an incr in the optical path length and therefore an increase in absorbance (decr in transmittance)

Front 91

Pulse oximetry is based on the assumption that..

Back 91

arterial blood is the only pulsatile absorber

Front 92

The Pulse ox can detect the cyclical changes in the signal due to..

Back 92

arterial blood flow during systole