Arterial Lines COPY Flashcards

1
Q

arterial line definition

A

like an IV but catheter inside artery

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2
Q

why are arterial lines more dangerous

A

if tubing is disconnected the patient could rapidly bleed to death

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3
Q

2 purposes for arterial lines

A

provide real time blood pressure

provide constant acess to blood samples for labs

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4
Q

catheter size used for adults arterial line

radial/brachial & femoral

A

20ga radial/brachial

18ga femoral

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5
Q

catheter size for pediatrics

A

20-22ga

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6
Q

catheter size for neonates

A

22-24ga

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7
Q

NIBP vs arterial line

A

NIBP tend to underread systolic and overread diastolic in comparison

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8
Q

what is the gold standard for BP?

A

arterial line

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9
Q

5 parts of a transducer system?

A
500mL bag of N/S
arterial line tubing with pressure transducer
pressure transducer cable
pressure bag for the N/S
transducer holder
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10
Q

what does the transducer do?

A

tells us how many mmHg are generated with each pulse

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11
Q

why use N/S vs why use heparinized saline?

A

N/S: less possibility of heparin induced thrombocytopenia

heparinized: less chance for aline to clot off

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12
Q

purpose of the pressure bag

A

prevent blood backup into the tubing bc arterial blood pressures are high
allows us to flush fluid into artery

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13
Q

how to flush arterial line

A

compressing the two doodads (or tail) on the transducer and opening roller clamp

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14
Q

Why should drugs/air bubbles never be given via the arterial route?

A

they can cause intense vasoconstriction and ischemia

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15
Q

what are the 4 reasons that an arterial line will not flush?

A

stopcocks turned off to the line
pressure bag underpressurized
roller clamp could be closed
aline clotted off

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16
Q

what should be done if an aline clots off?

A

try to aspirate the clot

then try to flush

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17
Q

4 steps of setting up an aline

A

1-set up bag and pressurize to 300mmHg
2- flush to remove air
3-connect the cable to the monitor
4-zero the a line

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18
Q

Why do you inflate the pressure bag to 300mmHg?

A

no backflow of blood

3-6mL/hr drip into artery to prevent clot

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19
Q

when we zero an aline what are we eliminating?

A

the effect of atmospheric pressure

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20
Q

4 steps to zeroing an aline

A

1-change monitor to from standard to 8 wave
2-turn stopsock nearest to transducer OFF to the patient and open to air (cap removed)
3- touch the ABP and push zero on monitor
4- after it shows zero turn stopcock off to atmosphere THEN put cap back on

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21
Q

why does caution need to be taken with where the stopcock is turned?

A

if it is off to the transducer then the patient could bleed to death

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22
Q

why do you put the cap on the stopcock after you turn the stopcock?

A

putting it on before could introduce pressure into the system

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23
Q

What are the materials needed for cannulating the artery?

A
chloraprep
4x4
tegaderm
tape
wrist support
lidocaine (if awake)
angiocath
(biopatch??)
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24
Q

2 catheter options for cannulating artery

A

20ga arrow catheter

regular 20ga catheter

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25
Q

2 options for wrist extenders

A

rolled up towel

plastic support

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26
Q

6 steps to aline placement

A
1- set up system and zero
2- position and prep
3- numb the area (if awake)
4-puncture artery and advance catheter
5- remove needle and attach
6- secure with tegaderm and tape
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27
Q

upstroke of a line

A

systole

correlates with cardiac contractility

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28
Q

downstroke of a line

A

diastole

correlates with SVR

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29
Q

how is MAP calculated aline

A

integrating the area under the pressure curve

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30
Q

sloped upstroke vs sharp upstroke

A

SLOPED: poorer contractility
SHARP: good contractility

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31
Q

slow fall downstroke vs sharp fall downstroke

A

SLOW: vasoconstriction (high SVR)
SHARP: vasodilation (low SVR)

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32
Q

dichrotic notch

A

blood slams into the aortic valve and then is projected forward

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33
Q

dampened waveform definition

A

smoother waveform that has lower amplitude and less detail

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34
Q

what does a dampened waveform do to systolic BP, diastolic BP, and MAP?

A

sys: underestimates
dia: overestimates
MAP: unchanged

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35
Q

5 causes of dampened waveform

A
1- compliance in tubing
2- clotted off catheter
3- kinked catheter from flexed wrist
4- low pressure in the system
5- air bubbles (they are a source of compliance)
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36
Q

4 ways to fix dampened aline

A

1-aspirate/flush clot
2- extend wrist
3- make sure pressurized
4- aspirate air bubbles

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37
Q

Before treating a low BP what things should you check?

A

low BP isnt due to damened wave

transducer is at the correct level

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38
Q

underdampened waveform definition

A

RESONANCE
too much waveform detail
“hyperresonant”
“overshoot”

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39
Q

what does a underdamped waveform do to systolic BP, diastolic BP, and MAP?

A

systolic: overestimatino
diastolic: underestimation
MAP: unchanged

40
Q

6 causes of underdamped waveform (or resonance)

A
1-defective transducer
2- tachycardia
3- long tubing
4- movement of catheter
5- catheter thats too large
6- increased vascular resistance
41
Q

what test do you use to test the accuracy of the aline waveform

A
square wave (high pressure) test
flush system
42
Q

optimally damped waveform after square test

A

after flush returns to baseline after one oscillation

43
Q

underdamped waveform after square test

A

wave oscillates multiple times before return to baseline

44
Q

overdamped waveform after square test

A

wave returns to baseline without any oscillations

45
Q

natural (resonant) frequency of aline

A

when pressurized system it oscillates at 20Hz natural frequency

46
Q

fundamental frequency of aline

A

arterial waveform has frequency that is equal to the pulse rate

47
Q

60 bpm = ____ Hz?

A

1Hz

48
Q

120bpm= ____ Hz?

A

2hz

49
Q

how much greater is the resonant frequency supposed to be than the fundamental frequency?

A

10x

50
Q

if the natural frequency <10x fundamental frequency what happens?

A

waveform become distorted/inaccurate

51
Q

constructive interference

A

two or more waves of similar frequency coincide to produce wave with higher peak amplitude

52
Q

resonance waveform

A

similar to constructive interference but

bc of external FORCE with similar frequency applied

53
Q

when can resonance occur with a lines?

A

bc pressurized tubing is external force if the natural frequency and fundamental frequency are similar then resonance possible

54
Q

what could happen if the natural frequency decreases below 20Hz or increases fundamental frequency above 2Hz?

A

resonance more likely

55
Q

where are the largest errors most likely to occur with resonance?

A

systolic pressure

56
Q

how can the amount of damping be measured?

A

damping coefficient

damping ratio

57
Q

what does damping counteract

A

resonance

58
Q

high damping coefficient

A

dampened waveform

59
Q

low damping coefficient

A

underdamping waveform

60
Q

what is the optimally damped coefficient?

A

0.6-0.7

61
Q

what is the most common aline cannulation site?

A

radial artery

superficial location and low complication rate

62
Q

ulnar artery aline placement

A
  • deeper and more difficult

- increased likelihood of nerve damage

63
Q

if you have failed to place an aline in the radial artery should you try to place an ulnar aline on the same arm?

A

no

bc hematoma may disrupt bloodflow to hand

64
Q

allens test (4)

A

1-pt makes fist
2- radial and ulnar arteries compressed
3- pt relaxes hand
4- pressure on ulnar released and observes how long it takes for blood to return

65
Q

<7 sec allen test

A

positive (adequate circulation)

66
Q

8-15 sec allen test

A

uncertain/ questionable

67
Q

> 15sec allen test

A

negative (inadequate circulation)

68
Q

brachial artery aline

A

limited collateral circulation

only use when other sites are not available

69
Q

axillary artery aline

A

has significant collateral flow
high risk of nerve damange
highest risk of cerebral emboli

70
Q

is the right or left axillary artery more likely to cause cerebral emboli?

A

right axillary artery

71
Q

what is the largest arterial line cannulation site?

A

femoral artery

72
Q

when is a femoral artery contraindicated?

A

femoral central line on same side

73
Q

what are the 3 complications unique to femoral aline placement?

A

1-hole in back of femoral artery lead to retroperitoneal bleed
2-femoral nerve damage
3- potentially higher infxn rate

74
Q

femoral aline placement pneumonic

A
NAVEL
lateral>medial
nerve
artery
vein
empty
lymphatic
75
Q

what is the most distal a line site?

A

dorsalis pedis and posterior tibial

76
Q

what two things happen as the cannulation site becomes more distal?

A
loses detail (more dampened)
higher systolic, lower diastolic and lower BP
77
Q

why does the systolic BP read higher the more distal you go?

A

pulse wave from previous pulse reflected from arterioles and added (similar to resonance)

78
Q

what are the 5 aline complications?

A
limb ischemia
neurologic injury
infection
hemorrhage (disconnection)
misinterpretation of data
79
Q

what are the 4 causes of limb ischemia

A

thrombosis from multiple attempts
small vessel compared to catheter
accidental medication injection
vasospasm

80
Q

what are the 4 causes of neurologic injury?

A

needle
hematoma near nerve
prolonged wrist extension
stroke because of thrombus or air emboli when flushing

81
Q

why shouldnt we perform a continuous flush?

A

stroke because of thrombus or air emboli when flushing

82
Q

misinterpretation of data acute hypertension

A

transducer falls to floor

83
Q

misinterpretation of data acute hypotension

A

transducer raised above phlebostatic axis

84
Q

hydrostatic pressure

A

effect of gravity on blood pressure

85
Q

supine BP

A

only force effecting pressure is flow

86
Q

standing pt BP

A

BP at base of foot is 133mmHg higher than artery at top of head (6ft tall)

87
Q

phlebostatic axis

A

4th intercostal space mid axillary line
represents external location of RA
“zero point”

88
Q

what height should the transducer be at?

A

phlebostatic axis

89
Q

if the transducer is below the phlebostatic axis what will be the BP

A

falsely high BP

90
Q

if the transducer is above the phlebostatic axis what will be the BP

A

falsely low BP

91
Q

for every inch the transducer is below the tip of the catheter how much fluid pressure increases?

A

1.87mmHg

92
Q

in sitting patients what will the height of the transducer estimate?

A

height on the body

you want it to be at the head

93
Q

when placing the transducer at the brain where do you want it?

A

external auditory meatus

94
Q

alternative to leveling at phlebostatic axis

A

taping to pt arm (not recommended esp. in sitting pts)

95
Q

arm height effect on BP

A

as long as the transducer is leveled at the phlebostatic axis it has no influence on BP

96
Q

do you have to zero the transducer at the level of the heart?

A

no