What is this?

• Simple accurate means of Simple accurate means of measuring arterial waveforms from measuring arterial waveforms from a regular blood pressure cuff.a regular blood pressure cuff.

• Analyzes components of the arterial Analyzes components of the arterial pulse wavepulse wave

Arterial Pulse Wave

• Result of 2 processes:Result of 2 processes:

– Ejection wave from the heart (stroke Ejection wave from the heart (stroke volume)volume)

– Modification of wave as it is ejected Modification of wave as it is ejected into a somewhat non-compliant or stiff into a somewhat non-compliant or stiff arterial system (impedence/vascular arterial system (impedence/vascular resistance)resistance)

Analysis of the Vascular Wave

• In theory, can provide informationIn theory, can provide information

– Cardiac functionCardiac function

– State of the arterial systemState of the arterial system

• The analysis is complex and The analysis is complex and interrelated and the term interrelated and the term “ventriculo-vascular coupling” has “ventriculo-vascular coupling” has been introduced to describe this been introduced to describe this relationship.relationship.

How is it recorded?

• Use a regular blood pressure cuff Use a regular blood pressure cuff around the armaround the arm

• Sensor system in the boxSensor system in the box

• Analyze the oscillometric signalAnalyze the oscillometric signal

– Therefore, cuff position does not matterTherefore, cuff position does not matter

Sequence

• Record blood pressure normallyRecord blood pressure normally

• Cuff deflates for ≈ 5 secsCuff deflates for ≈ 5 secs

• Cuff is reinflated to 30 mmHg above Cuff is reinflated to 30 mmHg above systole (suprasystolic)systole (suprasystolic)

• Held for 12 secs (2 respiratory cycles)Held for 12 secs (2 respiratory cycles)

• Cuff deflatesCuff deflates

• Recording of suprasystolic signals is Recording of suprasystolic signals is analyzedanalyzed

• Means of multiple variablesMeans of multiple variables

Features of Suprasystolic Recording

• Subaudible signals (<20 Hertz)Subaudible signals (<20 Hertz)

– 95% of energy of pulse wave is <1 95% of energy of pulse wave is <1 HertzHertz

• Reproducible at 20-30 mmHg above Reproducible at 20-30 mmHg above systolic pressuresystolic pressure

Benefits Over Intra-arterial Measurements

• Not influenced by dampening secondary Not influenced by dampening secondary to air or thrombus in arterial lineto air or thrombus in arterial line

• Not influenced by kinking of catheterNot influenced by kinking of catheter

• Stable, reproducible signalsStable, reproducible signals

• Non-invasive, sterility issues, etc.Non-invasive, sterility issues, etc.

• No technical skill requiredNo technical skill required

Benefits over Tonometry at the Wrist (AtCor – Omron)

• More proximal signals (axillary vs. radial More proximal signals (axillary vs. radial artery)artery)

• Less technician dependentLess technician dependent

• Single measurement (Tonometry Single measurement (Tonometry measures BP separately)measures BP separately)

• Quicker and more simpleQuicker and more simple

• What can you measure?What can you measure?

• What do the waves mean?What do the waves mean?

Physiology

Distal aorta

Exit of heart

DirectDirect

Reflected

Pulse Wave

• Incident waveIncident wave

•Reflection waveReflection wave

Wave Reflections

Intra-arterial Tracing

Incident Incident wavewave

Aortic Aortic reflection reflection

wavewave

Late Late reflection reflection

wavewave

Dicrotic Dicrotic notchnotch

Intra-arterial tracing

Pulsecor suprasystolic waveform

Concurrent Signals

RWR = Reflection Wave Ratio (da/ab x 100)

PS1 = Suprasystolic pressure wave amplitude

dp/dt = Contractility (Peak change in slope of PS1)

RWTT = Reflected Wave Transit Time (a-c)

SEP = Systolic Ejection Period (a-e)

RWR (reflection wave ratio) = da/ab x 100

PS1

RWTT

a

b

c

d

e

ab

da

SEP

dp

/dt

What can waves tell you or be used for?

• Vascular screeningVascular screening

• Monitoring long term medical Monitoring long term medical therapy, e.g., antihypertensivetherapy, e.g., antihypertensive

• Monitoring acute physiological Monitoring acute physiological changes in critical care changes in critical care environmentenvironment

Vascular Screening

• RWR increases withRWR increases with

– AgeAge

– HypertensionHypertension

– Vascular stiffnessVascular stiffness

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RWR = 17%

RWR = 65%

RWR = 325%

Baseline Reflection Wave Ratio vs. Age (n=200 hips)

R = 0.491

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RWR > 400% are over 70 years of age

Age

Baseline RWTT* vs. Age(n=200 hips)

*surrogate of pulse wave velocity

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R = 0.495

Arterial Stiffness vs. Brachial Blood Pressure

• Stronger predictor of cardiovascular disease and better guide to treatmentStronger predictor of cardiovascular disease and better guide to treatment• Stronger than other cardiovascular risk factorsStronger than other cardiovascular risk factors

Major Clinical Study OutcomeCAFE STUDY (Part of the Pfizer-

sponsored ASCOT study) - measured more than 2000 patients in the UK and Scandinavia, 2001-2006

Central blood pressure measurement showed big differences using two different drug regimens, clearly explaining different patient outcomes where brachial pressures showed no difference

USA NATIONAL INSTITUTE OF HEALTH’s STRONG HEART Study – measured more than 2400 patients for an average 4 years

Showed central pressures were strong predictors of cardiovascular outcomes, while brachial pressures were less predictive

REASON – Q: Does central pressure augmentation predict CV outcomes in renal failure patients?

Pressure augmentation was independently predictive of outcomes

ROTTERDAM - Q: Is arterial stiffness associated with risk of coronary heart disease and stroke?

Showed arterial stiffness is an independent predictor of coronary heart disease and stroke in asymptomatic individuals

Response to Medical Treatment: Effect of Stopping Losartan 50 mg/day

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• BP = 112/68 (80)BP = 112/68 (80) mmHgmmHg

• RWR = 33%RWR = 33%• dp/dt = 10 mmHg/secdp/dt = 10 mmHg/sec• PS1 = 0.6 mmHgPS1 = 0.6 mmHg

• BP = 144/85 (101) mmHgBP = 144/85 (101) mmHg

• RWR = 125%RWR = 125%• dp/dt = 15 mmHg/secdp/dt = 15 mmHg/sec• PS1 = 0.98 mmHgPS1 = 0.98 mmHg

CAFE Study

• Williams et al: Differential impact of Williams et al: Differential impact of blood pressure-lowering drugs on central blood pressure-lowering drugs on central aortic pressure and clinical outcomes: aortic pressure and clinical outcomes: principal results of the Conduit Artery principal results of the Conduit Artery Function Evaluation (CAFE) study. Function Evaluation (CAFE) study. Circulation 2006; 113: 1213-25Circulation 2006; 113: 1213-25

Monitoring Acute Monitoring Acute Physiological Physiological ChangesChanges

Total Hip Replacement

• 200 patients on operating table200 patients on operating table

• Supine and awake prior to sedationSupine and awake prior to sedation

• Non-selectedNon-selected

– Many treated with ACE inhibitors etc.Many treated with ACE inhibitors etc.

Total Knee Replacement

• 44 patients44 patients

• Randomized to ephedrine versus Randomized to ephedrine versus phenylephrine under extensive phenylephrine under extensive epidural anesthesiaepidural anesthesia

Pulsecor Changes

PropofolPropofol VasodilatorVasodilator

PhenylephrinePhenylephrine VasoconstrictorVasoconstrictor

Phenyl + Extensive Phenyl + Extensive epidural anesthesiaepidural anesthesia Cardiac DepressionCardiac Depression

Ephedrine (inotropic Ephedrine (inotropic agent)agent) Cardiac StimulationCardiac Stimulation

FluidFluid

Effect of Propofol

• Sedative/anesthetic agentSedative/anesthetic agent

• Known arterial dilatorKnown arterial dilator

• Mild cardiac depressionMild cardiac depression

Effect of Propofol(n=200)

BaselineBaseline PropofolPropofol P ValueP Value

MAPMAP 100 ± 11100 ± 11 80 ± 1280 ± 12 <0.0001<0.0001

Pulse Pulse PressurePressure 60 ± 1260 ± 12 45 ± 845 ± 8 <0.0001<0.0001

RWR (%)RWR (%) 130 ± 110130 ± 110 70 ± 5070 ± 50 <0.0001<0.0001

RWTTRWTT 0.16 ± .030.16 ± .03 0.19 ± .030.19 ± .03 <0.0001<0.0001

dp/dtdp/dt 9.4 ± 4.49.4 ± 4.4 8.2 ± 3.88.2 ± 3.8 <0.0001<0.0001

PS1PS1 0.541 ± .270.541 ± .27 0.498 ± .240.498 ± .24 0.00070.0007

Effect of Propofol (vasodilator)

• BP = 136/84 (99) mmHgBP = 136/84 (99) mmHg• HR = 79 bpmHR = 79 bpm

• RWR = 111%RWR = 111%• dp/dt = 5.63 mmHg/secdp/dt = 5.63 mmHg/sec• PS1 = 0.31 mmHgPS1 = 0.31 mmHg

• BP = 113/66 (78) mmHgBP = 113/66 (78) mmHg• HR = 80 bpmHR = 80 bpm

• RWR = 59.5%RWR = 59.5%• dp/dt = 5.91 mmHg/secdp/dt = 5.91 mmHg/sec• PS1 = 0.34 mmHgPS1 = 0.34 mmHg

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Effect of Intravenous Phenylephrine

• VasoconstrictionVasoconstriction

Vasoconstriction(TKR; n=22)

PropofolPropofol EA* + EA* + PhenylPhenyl P ValueP Value

MAPMAP 76 ± 876 ± 8 84 ± 884 ± 8 <0.0001<0.0001

HRHR 77 ± 1077 ± 10 59 ± 959 ± 9 <0.0001<0.0001

RWRRWR 56 ± 3056 ± 30 149 ± 69149 ± 69 <0.0001<0.0001

RWTTRWTT 0.193 ± .020.193 ± .02 0.178 ± .030.178 ± .03 =0.0378=0.0378

*EA = Epidural anesthesia

Effect of Phenylephrine (vasoconstrictor)

• BP = 115/70 (82) mmHgBP = 115/70 (82) mmHg• HR = 76 bpmHR = 76 bpm

• RWR = 42%RWR = 42%

• BP = 117/71 (84) BP = 117/71 (84) mmHgmmHg

• HR = 63 bpmHR = 63 bpm

• RWR = 212%RWR = 212%

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• BP = 122/64 (81) mmHgBP = 122/64 (81) mmHg• HR = 61 bpmHR = 61 bpm

• RWR = 40.7%RWR = 40.7%• dp/dt = 17.6 mmHg/secdp/dt = 17.6 mmHg/sec• PS1 = 1.05 mmHgPS1 = 1.05 mmHg

• BP = 152/88 (103) mmHgBP = 152/88 (103) mmHg• HR = 75 bpmHR = 75 bpm

• RWR = 74.7%RWR = 74.7%• dp/dt = 19.96 mmHg/secdp/dt = 19.96 mmHg/sec• PS1 = 1.2 mmHgPS1 = 1.2 mmHg

Cardiac Depression (Clinical model)

• Extensive epidural Extensive epidural autonomic autonomic blockade of the heartblockade of the heart

• Vasoconstriction Vasoconstriction no cardiac no cardiac stimulationstimulation

Cardiac Depression (TKR; n=22)

PropofolPropofol EA* + EA* + PhenylPhenyl P ValueP Value

MAPMAP 76 ± 876 ± 8 84 ± 884 ± 8 <0.0001<0.0001

Pulse Pulse PressurePressure 46 ± 946 ± 9 48 ± 848 ± 8 NSNS

HRHR 77 ± 1077 ± 10 60 ± 960 ± 9 <0.0001<0.0001

dp/dtdp/dt 8.6 ± 2.78.6 ± 2.7 5.4 ± 25.4 ± 2 <0.0001<0.0001

PS1PS1 0.52 ± 0.52 ± 0.170.17 0.35 ± 0.140.35 ± 0.14 <0.0001<0.0001

*EA = Epidural anesthesia

Effect of Phenylephrine + Extensive Epidural Anesthesia (Cardiac depression)

• BP = 115/70 (82) mmHgBP = 115/70 (82) mmHg• HR = 76 bpmHR = 76 bpm

• RWR = 42%RWR = 42%• PS1 = 0.58 mmHgPS1 = 0.58 mmHg• dp/dt = 11 mmHg/secdp/dt = 11 mmHg/sec

• BP = 117/71 (84) BP = 117/71 (84) mmHgmmHg

• HR = 63 bpmHR = 63 bpm

• RWR = 212%RWR = 212%• PS1 = 0.23 mmHgPS1 = 0.23 mmHg• dp/dt = 3.62 mmHg/secdp/dt = 3.62 mmHg/sec

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Ephedrine

• Cardiac stimulantCardiac stimulant

Effect of Ephedrine(n=109)

Post FluidPost Fluid Post Post EphedrineEphedrine P ValueP Value

MAPMAP 47 ± 747 ± 7 63 ± 1063 ± 10 <0.0001<0.0001

Pulse Pulse PressurePressure 38 ± 7.638 ± 7.6 46 ± 7.846 ± 7.8 <0.0001<0.0001

RWR (%)RWR (%) 29.5 ± 1829.5 ± 18 24.4 ± 2024.4 ± 20 0.0050.005

RWTTRWTT 0.241 0.241 ± .03± .03 0.228 ± .030.228 ± .03 0.00020.0002

dp/dtdp/dt 6.2 ± 2.46.2 ± 2.4 9.4 ± 3.89.4 ± 3.8 <0.0001<0.0001

PS1PS1 0.43 ± .160.43 ± .16 0.62 ± .240.62 ± .24 <0.0001<0.0001

Effect of Ephedrine(cardiac stimulant / inotrope)

• BP = 68/30 (40) mmHgBP = 68/30 (40) mmHg• HR = 57 bpmHR = 57 bpm

• RWR = 20%RWR = 20%• dp/dt = 4.72 mmHg/secdp/dt = 4.72 mmHg/sec• PS1 = 0.36 mmHgPS1 = 0.36 mmHg

• BP = 94/45 (58) mmHgBP = 94/45 (58) mmHg• HR = 64 bpmHR = 64 bpm

• RWR = 14%RWR = 14%• dp/dt = 8.6 mmHg/secdp/dt = 8.6 mmHg/sec• PS1 = 0.66 mmHgPS1 = 0.66 mmHg

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Effect of Exercise(15 min stationary bike, HR ≈130 bpm)

• BP = 129/70 (87) mmHgBP = 129/70 (87) mmHg• HR = 65 bpmHR = 65 bpm

• RWR = 44%RWR = 44%• dp/dt = 11.75 mmHg/secdp/dt = 11.75 mmHg/sec• PS1 = 0.66 mmHgPS1 = 0.66 mmHg

• BP = 164/72 (97) mmHgBP = 164/72 (97) mmHg• HR = 134 bpmHR = 134 bpm

• RWR = 6.2%RWR = 6.2%• dp/dt = 24.6 mmHg/secdp/dt = 24.6 mmHg/sec• PS1 = 1.01 mmHgPS1 = 1.01 mmHg

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Effect of Low Dose Epinephrine

• Low dose Low dose 3 µg/min 3 µg/min

• Increase stroke volumeIncrease stroke volume

• Decrease arterial toneDecrease arterial tone

Effect of Low Dose Epinephrine

• BP = 91/56 (66) mmHgBP = 91/56 (66) mmHg• HR = 57 bpmHR = 57 bpm

• RWR = 41%RWR = 41%• dp/dt = 7.94 mmHg/secdp/dt = 7.94 mmHg/sec• RWTT = 0.22 sec.RWTT = 0.22 sec.• PS1 = 0.64 mmHgPS1 = 0.64 mmHg

Epinephrine (3 Epinephrine (3 µg/min)µg/min)

No EpinephrineNo Epinephrine

• BP = 109/73 (83) mmHgBP = 109/73 (83) mmHg• HR = 49 bpmHR = 49 bpm

• RWR = 118%RWR = 118%• dp/dt = 7.81 mmHg/secdp/dt = 7.81 mmHg/sec• RWTT = 0.17 sec.RWTT = 0.17 sec.• PS1 = 0.46 mmHgPS1 = 0.46 mmHg

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Effect of Fluid(n=109)CVP increased 4 mmHg (mean)

Pre FluidPre Fluid Post FluidPost Fluid P ValueP Value

MAPMAP 43 ± 643 ± 6 47 ± 747 ± 7 <0.0001<0.0001

Pulse Pulse PressurePressure 36 ± 736 ± 7 38 ± 7.638 ± 7.6 <0.0001<0.0001

RWR (%)RWR (%) 31 ± 1931 ± 19 29 ± 1829 ± 18 NSNS

RWTTRWTT 0.242 ± .040.242 ± .04 0.241 ± .030.241 ± .03 NSNS

dp/dtdp/dt 5.2 ± 25.2 ± 2 6.2 ± 2.46.2 ± 2.4 <0.0001<0.0001

PS1PS1 0.344 ± .120.344 ± .12 0.431 ± .160.431 ± .16 <0.0001<0.0001

Effect of Snoring

Snoring

dPP = 122%

Snoring Eliminated

dPP = 59%

Atrial Fibrillation