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Anesthesia Equipment Exam 3 > Hemodynamic Monitoring > Flashcards

Hemodynamic Monitoring Flashcards

1
Q

Goals of the CV System

A
  • deliver oxygen and nutrients
  • remove waste
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2
Q

Hemodynamics

A
  • mvmt of blood through the closed circulatory system

influenced by:

  • BP
  • blood flow
  • characteristics of blood (viscosity, hydration, etc)
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3
Q

MAP Formula

A

MAP = CO x SVR

CO = HR x SV

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4
Q

Blood Flow Formula

A
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5
Q

Systolic Pressure

A
  • max pressure
  • pressure exerted when heart beats (systole)
  • reflects volume and speed of ejection and compliance of the aorta
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6
Q

Diastolic Pressure

A
  • minimum pressure
  • pressure exerted in between heart beats
  • reflects vascular resistance and compentence of the aortic valve
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7
Q

Circle of Life Visual

A
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8
Q

MAP

A
  • best indicator of tissue perfusion!
  • average driving pressure of blood during the cardiac cycle
  • MAP used to titrate pressures for induced hypotension or calculation of CPP
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9
Q

Pulse Pressure

A

PP = SBP - DBP

  • reflects difference in volume ejected from LV into arterial vessels and volume that is already there
  • function of SV and SVR
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10
Q

Widened PP

A
  • increased SV and decreased SVR
  • sepsis
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11
Q

Narrow PP

A
  • decreased SV and increased SVR
  • atherosclerosis
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12
Q

Arterial Pressure Monitoring

A

NIBP: auscultation or automatic (oscillometric)

Art Line: continuous pressure transduction

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13
Q

Auscultation

A
  • normal laminar flow in arteries produces little vibration and no sound
  • when artery is constricted, blood flow becomes turbulent causing the artery to vibrate and produce sounds
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14
Q

Karotkoff Sounds

A
  • turbulent flow that occurs when cuff pressure is >diastolic and <systolic></systolic>

<p>- tapping sounds associated w turbulent flow</p>

<p> </p>

</systolic>

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15
Q

Automatic Oscillometric Approach

A
  • even when sounds are barely audible, the oscillometric method can pick up the vibrations
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16
Q

Automatic BP Monitoring

A
  • measures oscillations in machine umbilical cable
  • measures MAP (point of max oscillation amplitude) and calculates SBP and DBP from formulas that examine the rate of change of the pressure pulsations
  • SBP identified as the pressure at which the pulsations are increasing and are at 25% to 50% of max
  • DBP is the most unreliable measurement and is recorded when the pulse amplitude has decreased to a small fraction of its peak value
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17
Q

Comparison of BP Measurements Between Korotkoff Sounds and Oscillometry (Visual)

A
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18
Q

Limitations of Oscillometric Measurement

A
  • Motion artifact
  • Bruising at cuff site
  • Nerve damage
  • Arterial or intravenous occlusion during inflation.
  • If proximal to pulse oximeter, damping of pulse ox waveform and reading
  • If SBP below 80, NIBP often over estimates MAP.
  • Must have correct cuff size
  • Dysrhythmias make values difficult to interpret or increase cycle time.
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19
Q

BP Cuff Sizing

A
  • ensure bladder length is 80% of arm circumference
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20
Q

Troubleshooting Automatic NIBP

A
  • air leaks at cuff, tubing, or connection to unit
  • pt must keep arm still
  • disconnect and reconnect to reset
  • most default to q5 min, increase to q2.5 min for induction
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21
Q

Invasive Arterial BP Monitoring

A

• Most accurate way to monitor beat to beat blood pressure and easy access to blood gas monitoring.

– Hemodynamic instability or predicted instability.

– Surgical procedure with anticipated significant blood loss or fluid shifts

– Monitoring of induced hypotension

– Monitoring response to vasoactive drugs

– NIBP is not feasible (burns, obese, shock)

– Repeated blood sampling

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22
Q

Invasive Art Line Waveform

A
  • shape depends on force generated by ventricle
  • speed of ejection
  • compliance of arterial vessels
  • rate of forward blood runoff (dependent on resistance to forward flow or SVR)
23
Q

Troubleshooting Pressure Monitoring System

A
  • keep it simple: minimize stopcocks, long tubing
  • remove air bubbles
  • zero line to midaxillary or phlebostatic axis (RA)
24
Q

Location of Phlebostatic Axis

A
  • 4th intercostal space midaxillary line
  • location of RA, where the tip of a CVP would lie
  • if below, BP will be erroneously high
  • if above, BP will be erroneously low
25
Q

Pressure Transducers: Normal vs Dampened/Overdampened (Visual)

A
26
Q

Art Line Complications

A
  • Distal ischemia, pseudoaneurysm
  • Hemorrhage, hematoma
  • Aterial embolization
  • Local infection, sepsis
  • Peripheral neuropathy
  • Misinterpretation of data
27
Q

Systolic Pressure Variation

A
  • mechanical ventilation
  • pulsus paradoxus is >10mmHg

- normally doesn’t exceed 10mmHg

28
Q

Pulse Pressure Variation

A
  • normal should not exceed 13%
  • (PPV) = (PPmax – PPmin) / PPmean
29
Q

CVP Monitoring

A
  • indication of RVEDV or Preload (fluid status)

- normal 6-10

• If abnormal, collect venous blood oxygenation samples

– Global tissue perfusion and oxygenation

30
Q

High CVP

A
  • persistant hypotension following fluid bolus and high CVP = myocardial congestion (MI, tamponade, tension pneumo)
31
Q

Low CVP

A

low CVP, tachycardia, and hypotension = hypovolemia

32
Q

CVP Catheter Types

A
  • single lumen: rapid, high volume resuscitation or pressure monitoring
  • multi lumen: drug therapy, nutrition support, pressure monitoring
33
Q

CVP Waveform

A
  • a -­‐ atrial contraction, absent in a fib, larger in tricuspid stenosis, pulmonary stenosis and pulmonary HTN
  • c – due to bulging of tricuspid valve into RA
  • x -­‐ atrial relaxation
  • v -­‐ rise in arterial P before tricuspid valve opens
  • y -­‐ atrial emptying as blood enters ventricle
34
Q

CVP Waveform (Visual #2)

A
35
Q

Pulmonary Artery Pressure Monitoring

A

• Better indicator of left heart pressure than CVP, especially when:

– LV function is impaired

– Significant valvular disease

– Pulmonary HTN

• PCWP – Best estimation of LVEDV (left V preload)

• CO – Thermodilution

• SVO2 (mixed venous oxygen saturation)

– Evaluate oxygen consumption and delivery

36
Q

PA Catheters

A
  • multi-lumen polyvinylchloride catheter w balloon at tip
  • inflation of balloon ensures that blood flow will move balloon/catheter forward in the direction of blood flow
37
Q

Insertion of PA Catheter

A
  • R heart catheterization w large bore introducer sheath
  • typically via subclavian or IJ veins
  • seldinger technique (introducer then guidewire then catheter over wire)
38
Q

Prior to Insertion of PA Catheter

A
  • Flush all lumens with solution
  • Check integrity of balloon

– Always deflate passively

  • Prepare transducer system that has been leveled and zeroed.
  • Connect lines to appropriate lumens

– PA pressure monitor is distal

– CVP pressure monitor is proximal

39
Q

Catheter Insertion

A
  • PA catheter is inserted to a depth of 20cm.
  • A CVP waveform must be idenAfied to confirm that the PAC type is in the R vena cava or atrium.
  • Balloon then fully inflated, blood will carry or float the catheter through the RA, RV and into the PA.
40
Q

Progression of PA Catheter (Visual)

A
41
Q

PA Catheter Measures

A

Systolic: 15-30 mmHg

Diastolic: 5-15

PACWP: 4-14

42
Q

Thermodilution CO

A
  • cold water injected through PA catheter and the change in temp from proximal to distal ends of catheter is measured and analyzed against time
  • thermistor tip
43
Q

Complications of CVP and PA Lines

A
  • Infection
  • Pneumothorax
  • Vessel erosion or perforation
  • Venous air embolism
  • Hemorrhage (rupture of PA)
  • Cardiac dysrhythmias
44
Q

LiDCO

A
  • lithium dilution cardiac output
  • minimally invasive continuous CO monitoring

• Uses the pulse pressure analysis algorithm for continuous measurement of changes in CO

– Derive SV from arterial pressure waveform

– Calculate HR

– CO = SV*HR

– calibration

• Provides info on SV variation and pulse pressure variation

45
Q

EKG

A

• Monitors electrical impulses through the heart

– HR

– Arrhythmias

– Myocardial ischemia

– Pacemaker function

– Electrolyte abnormalities

– NOT contractility or output! (PEA)

46
Q

How does EKG monitoring work?

A
  • Silver chloride electrode with a conductive gel which decreases the electrical resistance of the skin.
  • A very small electrical signal is amplified and then broadcasted over a 0.01 to 250 Hz bandwidth.
  • Prone to electrical interference

– Clean dry skin

47
Q

EKG Lead Placement

A

• Lead II – Rhythm detection

– P waves

– Inferior portion of the heart supplied by the RCA

• Lead V5 – Bulk of the LV supplied by LAD placed 5th intercostal space anterior axillary line

• Lead I – Circumflex artery

48
Q

Respiratory Impedence of EKG

A
  • Impedance pnuemography
  • In short, measures movement of the chest electrodes.
  • Anesthesia monitors do not default to show this, but helpful with sedation cases.
49
Q

Pulse Oximetry

A
  • measurement of arterial Hgb oxygenation
  • oxygenation and deoxygenated blood absorb light differently

oxyHgb: infrared, 940nm wavelength

REDuced Hgb: red, 660 nm

50
Q

Pulse Ox: Beer-Lambert Law

A
  • Measure “pulsatile signals across perfused tissue at two discrete wavelengths”
  • Absorbance of light indicates state of hemoglobin
  • Two Light Emi|ng Diodes (LEDs)

– Infrared (940 nm wave length) – oxyhemoglobin

– Red (660 nm wave length) -­‐ REDuced hemoglobin

• Light detector

51
Q

Light Absorbance Visual

A
52
Q

Carboxyhemoglobin

A
  • CO poison
  • appears like oxyHgb at 660 nm
  • raises appearance of oxygenated Hgb
  • falsely HIGH readings
53
Q

Methemoglobin

A
  • benzocaine, methylene blue
  • gives a sat of 85% no matter what the true oxygenation is
54
Q
A

Anesthesia Equipment Exam 3 (2 decks)

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