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Monitoring of CV Patient I > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Pulse Pressure

A

determined by the interaction of the stroke volume of the heart, compliance of the aorta, and the resistance to flow in the arterial tree

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2
Q

Mean Arterial Pressure

A

Actual mean is determined by the area under the arterial pressure curve divided by the beat period

Calculus: integration of the area under the curve

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3
Q

Why is MAP a good assessment tool?

A
  • mean pressure the same in all parts of the arterial tree
  • mean pressure not significantly affected by overshoot, artifact and the frequency response characteristics of the system
  • pulmonary and SVR values are calculated using the mean pressure
  • mean pressure represents the inlet pressure to the systemic and cerebral capillary networks
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4
Q

Causes of False-High Reading

A 
Cuff too small
cuff not centered over the brachial artery
cuff not applied snugly
arm below heart level
Very obese arm
cone-shaped arm
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5
Q

Causes of False-Low Reading

A

Cuff too large
arm located above heart level
Failure to correctly determine the onset of the first Korotkoff sound

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6
Q

Auscultation

A

May be up to 20 mmHg lower than direct
Proper cuff size: obese or patients with cone-shaped arms
Deflate cuff at at approx. 3mmHg/sec
Diastolic reading muffled (hyperdynamic)
Problems with damping of sounds in pt w. reduced stroke volume and severe vasoconstriction
concerns with frequency of pressure determination

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7
Q

Complications of deflating cuff too fast or slow?

A

Too fast- underestimate values

Too slow creates venous congestions which distorts Korotkoff sounds

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8
Q

Indirect BP Manual Techniques

A 
Auscultation 
Palpation- determine systolic only
Auscultation assisted by Doppler- determine systolic only; easier to determine pressure in "shocky" patients
Manometer oscillation observation
Photoelectric devices
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9
Q

Photoelectric Devices

A 
Indirect manual technique
pulse ox is an example
determines sytolic only
patient motion is a problem
problems when arterioles of extremities are constricted
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10
Q

Manometer oscillation observation

A

Indirect Manual Techniques
Determine systolic and mean/first oscillation
systolic/maximal oscillation
mean/minimal oscillation in hypotensive patients

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11
Q

Indirect Automated Technique Examples

A

oscillometery- detection of pulsatile arterial wall vibrations/most commonly used
Infrasound- detect pulsatile vibrations via microphone
Ultrasonic determination of axial flow- use doppler to detect sound of flowing blood (TEE)
Arterial tonometry-pressure sensor over radial artery detects pusatile forces

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12
Q

Indirect Automated Technique Characteristics

A

Depend on adequate pulsatile blood flow to extremities
Many determine mean pressure
Good for following trends in stable patients
Poor results in hypotension or pts receiving potent vasoactive drug titration

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13
Q

Indirect vs. Direct: Patient Factors

A

Regional arterial pressure gradients due to: atherosclerosis, peripheral vascular disease, aortic dissection, arterial embolism, surgical retraction, patient position

Generalized arterial pressure gradients due to: severe vasoconstriction and shock, peripheral vasodilation with rewarming during and after CPB, normal widening of the peripheral pressure pulse

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14
Q

Indirect vs. Direct: Technical Factors

A 
Cuff problems: too small, arm shape, extrinsic cuff compression, limb position relative to heart
Rapid deflation (underestimation)
Physiologic problems and method limitations- rapid P changes, dysrhythmias, severe vasoconstriction and shock, shiver and pt movement, BTBV
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15
Q

Vasoconstricted patients with low stroke volume

A

Obtained pressures with indirect method underestimate true systolic pressure

oscillometry, palpation, and auscultation: indirectly measure blood pressures tend to underestimate systolic BP and overestimate diastolic pressure (dampened)

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16
Q

Adequacy of tissue perfusion in direct method

A

difficult to determine by direct method based on pressure readings

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17
Q

Direct Continuous Intra-Arterial Pressure Monitoring

A

Most reliable method of determining real-time systemic arterial systolic, diastolic and mean pressures
Relatively pain-free
Simple
Relatively low-risk access for arterial blood sampling

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18
Q

Indications for Arterial Cannulation

A

Need continuous arterial pressure monitoring

Patient has a need for serial blood gases

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19
Q

Who needs continuous arterial pressure monitoring?

A

critically ill, injured, undergoing major surgery

Provides ability to detect sudden changes, evaluate changes in the trend, immediately assess effects of therapy

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20
Q

Who needs serial blood gases?

A

Respiratory failure
Management of ventilator support
Treatment of severe acid-base disturbances
Need more than three or four arterial blood samples on a daily basis

21
Q

Contraindications for Arterial Cannulation

A

Peripheral Vascular Disease
Hemorrhagic disorders
On anticoagulants or receiving thrombotic agents

22
Q

Where should you not insert a catheter?

A

area of infection
site previous vascular surgery (cutdown)
through synthetic vascular graft material

23
Q

Pressure Wave Generation

A

Ventricular ejection creates blood flow and a pressure wave
Pressure wave precedes the actual blood flow of blood
Creation of pressure wave-form is affected by this relationship

24
Q

Speeds of Pressure Wave & Blood flow

A

pressure wave: 10 m/s
blood flow: 0.5 m/s
Almost sound like a phase shift-out of sync

25
Q

True Pressure Wave Phases

A

Phase 1: Inotropic component
Phase 2: Volume Displacement Curve
Phase 3: Late Systole and Diastole

26
Q

Phase 1: Inotropic Component

A

Aortic Valve Opens
Energy created by contracting LV transferred to the aorta
Pressure wave created- starts moving down arterial tree
Simultaneously- first part of stroke volume pumped into aortic root
Anacrotic rise (dP/dT)- steepness, rate of rise & heigh of rise related to rate of acceleration of blood (indication LV contractility)

27
Q

What dose Anacrotic rise indicate?

A

LV contractility

28
Q

Phase 2: Volume Displacement

A

Movement of blood into aorta fills out and sustains the pressure pulse
Rounded appearance results from: continued ejection of the SV, displacement of blood, distention of arterial walls
Anacrotic notch: may be present, mark change from inotropic component to displacement
Low stroke volume (curve narrow with low amplitude)

29
Q

What marks change from inotropic component to displacement?

A

Anacrotic notch

30
Q

Phase 3: Late Systole & Diastole

A

Sloping decline- rate of peripheral runoff exceeds vol input
Closure of aortic valve: start of diastole, dicrotic notch
Continuous decline as blood moves from aortic root to the peripheral vessels
Undulations may result from reflected pressure waves

31
Q

High amplitude of inotropic spike

A

Increase rate of LV pressure generation & increased acceleration of aortic blood flow
Increased reflection of pressure waves from the periphery: vasoconstriction
Overshoot artifact

32
Q

Decreased amplitude of inotropic spike

A

myocardial depression
hypovolemia
decreased reflection of pressure wave from the periphery (vasodilation)

33
Q

High Pressure, Low Flow

A

Low flow: might be perfusing core but periphery gets acidotic

34
Q

Low Pressure, High Flow

A

Perfusing all tissues; not much downside

35
Q

Maintain flow using drugs

A

never change flow and give systemic vasoconstrictor making extremities hypoxic

36
Q

Overshoot

A

Overshoot of systolic pressure most common artifact seen in clinical practice
May come and go (changing HR, development of hyperdynamic conditions)
Due to underdamping or inadequate frequency response

37
Q

Effects on Pressure Waves

A

Gravitational Effects
Reflected Waves Effects
Physiological Effects

38
Q

Gravitational Effects

A

Vertical patient vs. supine
Vertical: pressure decreases moving upward from heart
Pressure increases moving downward from heart
pressure the same at all points at same vertical level
Supine: no differences due to gravity
“Orthostatic Hypotension”

39
Q

Standard Reference Level for blood pressure

A

Heart!

40
Q

Reflected Pressure Waves

A

Pressure waveform precedes the actual flow of blood: ventricles generate tension then contract
Pressure waves reflected back toward aortic root by smaller distal vessels: added to pressure waveform as tit travels down the arterial tree (fourier analysis)
Pulse pressure increases as wave travels down the arterial tree (sys higher, diastolic lower)

41
Q

Since pulse pressure increases as it goes down the arterial tree: underdamping or overdamping?

A

Underdamping

Systolic higher, diastolic lower

42
Q

Normal Pulse Pressure

A

Greater than 40 mmHg is abnormal

43
Q

High Pulse Pressure

A 
Heart Problems (older adults)
Stiffness of aorta (calcification)
Athersclerosis
Aortic dissection
Endocarditis
Chronic aortic regurgitation (AI)
Fever
Anemia
Pregnancy
Anxiety
Heart Block
Raised ICP
44
Q

Low (Narrow) Pulse Pressure

A

Poor Heart function (see this a lot)
Most common cause: drop in LV stroke volume
In trauma: significant blood loss (insufficent preload leading to reduced CO)
If extremely low: 25mmHg or less the cause may be low SV as in CHF or shock

45
Q

Physiological Factors affecting Waveforms

A 
Arrythmias
Hypertension
Hypotension
Age
Vasoconstriction
Hypovolemia
Respiration Variation
46
Q

Effect of Hypotension on Arterial Waveform

A

Peak of inotropic component and dicrotic notch disappear

Waveform looks to be damped

47
Q

Aging

A

Difference between central aortic and distal systolic pressures decreases
-minimal change in the pressure pulse
-loss of arterial compliance
Inotropic component tends to be dominant

48
Q

Direct Arterial Cannulation Locations

See pg 151-152 chart in book

A 
Radial artery
Brachial artery
Axillary artery
Femoral artery
Dorsalis Pedis Artery
49
Q

Direct Arterial Complications

A 
Embolism
Vascular insufficiency (distal ischemia)
Iscemic necrosis of overlying skin
Infection
Hemorrhage
Accidental intra-arterial drug injection
Vasculitis
Arterial dissection

Monitoring of CV Patient I (4 decks)

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