Transcript Invasive blood pressure monitoring - lgh

Invasive blood pressure
monitoring in critical care
Presented by Ri 施易青
Outline
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Introduction
Arterial pressure waveform
Controversial aspect of IBP
monitoring
Conditions that affect arterial
waveform morphology
Pros and cons of various cannulation
sites
History
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First invasive blood pressure
monitoring: Stephen Hales’ horse
(1733)
First attempt in human: Faivre’s
amputee (1856)
Clinical use: Lambert and Wood
(1947)
Modern cannulation technique: Barr
(1961)
CV surgery in the 60s
Indications
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Continuous monitoring of BP
Serial external monitoring inadequate
Hypotension or hypertension requiring
vasoactive drugs
Respiratory illness or mechanical
ventilation requiring frequent blood gases:
>3X/D for arterial sticks
>5X/D for combined arterial and/or
venous sticks
Major Surgery: Especially CV or neuro.
procedures
Contraindications
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Absence of collateral flow
Raynaud's disease and cold infusions
Angiopathy, coagulopathy (recent anti-coag. or
thrombolytic infusion increases risk of hematoma
and compressive neuropathy), atherosclerosis:
Use Caution!
Avoid locating near A-V fistula, and inserting
through synthetic graft
Diabetics at increased risk of complications
Avoid local infection, burn or traumatic sites
Avoid extremities with carpal tunnel syndrome
The Pressure-pulse
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1st shoulder (the Inotropic Component):
early systole, opening of aortic valve, transfer
of energy from contracting LV to aorta
2nd shoulder (the Volume Displacement
Component): produced by continuous
ejection of stroke volume from LV,
displacement of blood, and distention of the
arterial wall
Diastole: when the rate of peripheral runoff
exceeds volume input to the arterial
circulation
Possible Information gained
from a pressure waveform
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Systolic, diastolic, and mean
pressure
Myocardial contractility (dP/dt)
Peripheral vascular resistance (slope
of diastolic runoff)
Stroke volume (area under the pulse
pressure curve)
Cardiac output (SV x HR)
Is arterial waveform predictive of
cardiac contractility?
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It is only “aortic arch pressure” that
can be used to measure LV
contractility, not “peripheral pressure”
As BP is measured farther into
periphery:
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The anacrotic and dicrotic notches
disappear
The waveform appears narrower
The systolic and pulse pressure
increase
The upstroke becomes steeper
The diastolic and mean pressure
decrease
Morphology changes as a result of
peripheral reflexions:
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Reflexion of waves due to the
tapering diameter
Reflexion due to changing content of
the arterial wall
Reflexion also occur at branching
points of vessels
Is the arterial waveform predictive
of stroke volume?
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The pressure does not predict flow
The distensible aortic arch act as a
“fixed-capacity, high pressure
reservoir”
Flow in the arterial tree is continuous,
with 10-20 percent of LV power
being pulsitile
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Cullen et al: Correlation coefficient of
0.82 between changes in stroke
volume and changes in peripheral
systolic pressure in halothaneinduced anesthesia status, where
peripheral vascular resistance
remained essentially unchanged
Interpretation of blood pressure measurement in anesthesia
Anesthesiology, 40:6 1974
Role of direct arterial pressure
monitoring
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Provides trends over a wide range
Unreliable as absolute hemodynamic
values
As a reminder
“A needle in an artery does not
guarantee a pressure or accuracy
any more than an endotracheal tube
guarantee a patent airway.”
Conditions that affect arterial
waveform morphology
Hyperdynamic pulse
 Pulsus paradoxus
Reverse pulsus paradoxus
 Pulsus alternans
 Pulsus bisferens
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Hyperdynamic pulse
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Aortic regurgitation
AV fistula
Thyrotoxicosis
Anemia
Pregnancy
sepsis
Pulsus paradoxus
Cause of pulsus paradoxus
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Change in pleural pressure
associated with breathing
Anatomic relationship between two
ventricle chambers
D/D of Pulsus paradoxus
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Constrictive pericarditis or cardiac
tamponade
COPD
Asthma
Tension pneumothorax
Reverse pulsus paradoxus
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An exaggeration of the rise in
systolic BP during mechanical
ventilation
A sensitive indicator of hypovolemia
in mechanically ventilated p’t
Pulsus alternans
Cause of pulsus alternans
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A sign of decreased myocardial
contractility (deletion of the number
of myocardial cells contracting on
alternate beats)
An alteration in diastolic volume
leading to beat-to-beat variation in
preload
D/D of pulsus alternans
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LV dysfunction
Pericardial effusion
Pulsus bisferens
Pulsus bisferens
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Hypertrophic cardiomyopathy
Aortic regurgitation
Advantages and disadvantages
on various cannulation sites
Radial
 Brachial
 Femoral
 Axillary
Dorsalis pedis
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artery
artery
artery
artery
artery
Radial artery
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Advantages: easy to cannulate,
accessible during most type of
surgery, good collateral circulation,
patient comfort, Allen’s test
Disadvantages: thormbus formation,
possible injury to nerve,
augmentation of SBP,
Brachial artery
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Advantages: easy to cannulate,
larger catheter, less SBP
augmentation, collateral vessels
Disadvantage: uncomfortable for p’t,
median nerve damage
Femoral artery
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Advantages: prolonged use, useful in
shock p’t, largest catheter
Disadvantages: atherosclerotic
plaque may break off, massive
hematoma, difficult to immobilize
Axillary artery
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Advantages: large size, useful in
peripheral artery dz and shock,
proximity to aorta,
Disadvantages: neurologic
complication, technically difficult
Dorsalis pedis artery
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Advantages: dual circulation
Disadvantages: greatest SBP
augmentation, thrombus formation,
difficult to immobilize, impossible to
walk
Take home message
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The arterial system functions as a
damped, resonant, transmission line,
transmitting various frequencies with
different degrees of attenuation.
The clinician must dissuade himself
from the belief that the peripheral
pressure accurately reflects aortic
arch pressure.
reference
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Monitoring in Anesthesia and Critical Care
Medicine, 2nd edition. 1990
Hemodynamic monitoring: Invasive and
Noninvasive Clinical application, 2nd edition.1995
Cullen et al: Interpretation of blood pressure
measurement in anesthesia. Anesthesiology, 40:6
1974
Thanks for your attention!