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Perf Monitoring > test 8 > Flashcards

test 8 Flashcards

1
Q

WHAT CAUSES CHANGES IN CARDIAC OUTPUT

A 
• Decreased contractility
     – Myocardial damage
     – Drug effects
     – Acidosis
     – Hypoxia
• Decreased preload
• Changes in SVR
     – Increased SVR: arteriosclerosis, hypertension
     – Decreased SVR: septic shock
• Decreased ventricular flow (valve disease)
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2
Q

VARIABLES AFFECTING

CARDIAC OUTPUT

A
  • Metabolic rate and oxygen demand
  • Gender
  • Body size
  • Age
  • Posture
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3
Q

Factors increasing metabolism

A 
– Sepsis
– Strong emotion
– Major trauma
– Surgery
– Exercise
– Fever
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4
Q

CI does not account for

A

– personal build (fat vs muscle)
– diseases that alter metabolism, such as thyroid disorders
– fluid that may alter body weight without increasing
metabolism
• Edema
• Ascites
• Diuresis

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5
Q

WHAT IS AN ANATOMIC

SHUNT?

A

Volume and circulatory flow changes that create
differences in saturation, pressure and flow in the
chambers

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6
Q

LEFT→RIGHT SHUNTING

A
  • Overloads the right ventricle
  • Pulmonary blood flow > Systemic blood flow
  • Seen in atrial septal defects (ASD), ventricular septal defects (VSD), patent foramen ovale (PFO) and acyanotic congenital anomalies
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7
Q

RIGHT→LEFT SHUNTING

A
  • Pulmonary blood flow < Systemic blood flow

* Seen in Tetralogy of Fallot (TOF) and cyanotic congenital defects

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8
Q

WHAT IS THE MOST IMPORTANT HEMODYNAMIC MEASUREMENT TO ASSESS A PATIENT’S PERFUSION STATUS

A

Cardiac output

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9
Q

INVASIVE WAYS TO MEASURE CARDIAC

OUTPUT

A 
• Fick oxygen consumption
method
• Dye-dilution method
• Thermodilution method
• FloTrac System
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10
Q

NONINVASIVE WAYS TO MEASURE CARDIAC

OUTPUT

A
  • Doppler Ultrasonography & Echocardiographic Imaging (ECHO)
  • Thoracic electrical bioimpedance
  • Electromagnetic flow probes
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11
Q

FICK OXYGEN CONSUMPTION METHOD

A

-Simultaneous measurement of:
• Arterial oxygen content (CaO2)
• Mixed venous oxygen content (CvO2)
• Oxygen uptake by lungs

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12
Q

FICK METHOD - ADVANTAGES

A

• Most accurate when cardiac output is low

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13
Q

FICK METHOD-DISADVANTAGES

A

• Patient must maintain steady hemodynamic and
metabolic state for the length of the test (3 minutes)
• Requires multiple people
• Time consuming
• Requires meticulous technique
• Not easily repeatable / not continuous
• Results not readily available for immediate clinical intervention
• Not valid in presence of intra-cardiac and intrapulmonary
shunts
• Least accurate with high cardiac output

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14
Q

DYE-DILUTION METHOD

A

• Right side injection (PA) of indocyanine green dye with
a continuous sample drawn simultaneously via a
systemic artery at a constant rate
• Plot the concentrations graphically
-open system- no recirculation
-closed system- recirculation

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15
Q

Indicator characteristics for dye-dilutional method

A 
– mixes well with blood
– easy to determine
concentration
– stable
– not retained by the
body
– not toxic
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16
Q

Indicator used for dye-dilutional method

A

– O2
– indocyanine dye (cardiogreen)
– radio-iodated serum albumin
– temperature

17
Q

DYE DILUTION - ADVANTAGES

A

• Most accurate in high-cardiac output states

18
Q

DYE DILUTION - DISADVANTAGES

A

• Not valid with intra-cardiac shunts, valve
regurgitation or shock
• Dye unstable / photosensitive – must be mixed daily
• Risk of allergic reaction to dye
• Requires calibration using sample of patient’s blood
• Carefully metered blood withdrawal
• One shot estimate
• Patient must be in stable metabolic state for approximately 40 seconds
• Time consuming
• Least accurate if the output is low

19
Q

THERMODILUTION

A
  • deposit cold temp into RA by PA cath and it mixes with the blood and the PA where the tip of the catheter measures temp
  • repeat 3 times with 90 sec in between
20
Q

THERMODILUTION READING

A
  • area under the curve

- the larger the area the smaller the CO

21
Q

PATIENT-GENERATED ERRORS FOR THERMODILUTION

A
  • Alterations in ventricular performance (arrhythmias)
  • Low cardiac output
  • Intracardiac flow abnormalities
22
Q

TECHNIQUE-GENERATED ERRORS FOR THERMODILUTION

A 
• Wrong injectate
• Wrong injectate temperature
• Wrong injectate volume
• Injection speed too slow
• Thrombus formation on the catheter tip
   – delays heating/cooling of the thermister
• Plasma protein deposition on catheter
• Thermister defect
• Incorrect computation factor entered
• Rapid IV infusions during measurement
• CPB rewarming
23
Q

THERMODILUTION - ADVANTAGES

A

• No blood withdrawal
• Easily and quickly performed
• Continuous information can be available
– Venous Pulmonary Artery Catheter
• Results readily available for immediate clinical intervention

24
Q

THERMODILUTION - DISADVANTAGES

A
  • Not accurate in presence of tricuspid regurgitation and intra-cardiac shunts
  • Least accurate if cardiac output is low
  • Results may vary based on location in respiratory cycle
25
Q

FLOTRAC SYSTEM

A

• A sensor attaches to any arterial catheter and uses a
clinically validated algorithm to provide CO measurements updated every 20 seconds
• Calculates stroke volume based on arterial pressure,
age, gender and BSA and multiplies it by the pulse rate
• Allows accurate insight to patient’s volume status

26
Q

FLOTRAC SYSTEM MEASURES

A
  • CO
  • CI
  • SV
  • SVI
  • SVV (stroke volume variation)
  • SVR
27
Q

3 methods to measure preload responsiveness

A

– Stroke volume variation (SVV)
• Highly sensitive and specific indicator for pre-load responsiveness
• Ventilated patients only
• Expressed as a percentage (Normal: ~10%)
– Passive leg raising (PLR)
• Spontaneous ventilation
• Arrhythmias
– SV fluid challenge
• Administration of a small volume of fluid and observing corresponding change in SV

28
Q

FLOTRAC - ADVANTAGES

A
  • Connects to any arterial catheter
  • Clinically validated
  • Automatic
  • No experienced technician required
29
Q

FLOTRAC - DISADVANTAGES

A
  • Arterial tracing must be accurate
  • Not validated in VADs or TAHs
  • Possible inaccurate measurements with IABP
  • Arrhythmias cause inaccuracies
  • Not used in pediatrics
30
Q

DOPPLER ULTRASONOGRAPHY
AND ECHOCARDIOGRAPHY
(ECHO)
(noninvasive)

A 
• Indirect assessment of cardiac output
1. DOPPLER: assesses
blood flow velocity
2. ECHO: assesses aortic
diameter
31
Q

DOPPLER PRINCIPLE

A

• Transducer transmits ultrasonic waves of known

frequency from moving cells

32
Q

DOPPLER AND ECHO DISADVANTAGES Technique Factors

A

– Time consuming
– Bulky equipment
– Experienced operator
necessary

33
Q

DOPPLER AND ECHO DISADVANTAGES patient factors

A 
– Anemia
– Tachycardia
– Thick chest walls
– Large sternal incisions
– Tracheostomy
– Emphysema
34
Q

THORACIC ELECTRICAL

BIOIMPEDENCE

A
  • high Impedence = poor conductors = air and bone
  • low Impedence = good conductors = blood
  • patches on body that measure the systole and diastole blood volume in the thoracic cavity based on impedence
35
Q

TEB - ADVANTAGES

A
  • Non-invasive continuous real-time data
  • Cost effective
  • Quick
  • Can be used in a variety of clinical settings
  • Wide clinical application
36
Q

TEB - DISADVANTAGES

A 
• Accuracy is variable with
– Sepsis
– Arrhythmias
– L to R shunts
– Aortic regurgitation
37
Q

BLOOD FLOW

PROBES

A

• Electromagnetic induction – move electrical conductor through magnetic field get induced voltage proportional to velocity of motion
• Measures the mean velocity of flow (i.e. cm/sec)
• Calculates flow
• Ultrasonic flow meter: measures the velocity
of a fluid with ultrasound to calculate volume
flow

38
Q

Gold standard

A
  • none

- each have advantages and disadvantages

Perf Monitoring (6 decks)

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