Invasive blood pressure Invasive blood pressure monitoring in critical caremonitoring in critical care

Presented by Ri Presented by Ri 施易青施易青

OutlineOutline Introduction Introduction Arterial pressure waveformArterial pressure waveform Controversial aspect of IBP monitoringControversial aspect of IBP monitoring Conditions that affect arterial waveform Conditions that affect arterial waveform morphologymorphology Pros and cons of various cannulation sitPros and cons of various cannulation siteses

HistoryHistory First invasive blood pressure monitoring:First invasive blood pressure monitoring: Stephen Hales’ horse (1733) Stephen Hales’ horse (1733) First attempt in human: Faivre’s amputFirst attempt in human: Faivre’s amputee (1856)ee (1856) Clinical use: Lambert and Wood (1947)Clinical use: Lambert and Wood (1947) Modern cannulation technique: Barr (19Modern cannulation technique: Barr (1961)61) CV surgery in the 60sCV surgery in the 60s

IndicationsIndications Continuous monitoring of BPContinuous monitoring of BP Serial external monitoring inadequateSerial external monitoring inadequate Hypotension or hypertension requiring vasoacHypotension or hypertension requiring vasoactive drugstive drugs Respiratory illness or mechanical ventilation rRespiratory illness or mechanical ventilation requiring frequent blood gases:equiring frequent blood gases: >3X/D for arterial sticks>3X/D for arterial sticks >5X/D for combined arterial and/or venous stic>5X/D for combined arterial and/or venous sticksks Major Surgery: Especially CV or neuro. proceduMajor Surgery: Especially CV or neuro. proceduresres

ContraindicationsContraindications 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-pulseThe Pressure-pulse 1st shoulder 1st shoulder (the Inotropic Component):(the Inotropic Component): early sy early systole, opening of aortic valve, transfer of energy frstole, opening of aortic valve, transfer of energy from contracting LV to aortaom contracting LV to aorta 2nd shoulder 2nd shoulder (the Volume Displacement Compo(the Volume Displacement Component):nent): produced by continuous ejection of stroke produced by continuous ejection of stroke volume from LV, displacement of blood, and distevolume from LV, displacement of blood, and distention of the arterial wallntion of the arterial wall Diastole: when the rate of peripheral runoff exceeDiastole: when the rate of peripheral runoff exceeds volume input to the arterial circulationds volume input to the arterial circulation

Possible Information gained Possible Information gained from a pressure waveformfrom a pressure waveform

Systolic, diastolic, and mean pressureSystolic, diastolic, and mean pressure Myocardial contractility (dP/dt)Myocardial contractility (dP/dt) Peripheral vascular resistance (slope of Peripheral vascular resistance (slope of diastolic runoff)diastolic runoff) Stroke volume (area under the pulse preStroke volume (area under the pulse pressure curve)ssure curve) Cardiac output (SV x HR)Cardiac output (SV x HR)

Is arterial waveform predictive of Is arterial waveform predictive of cardiac contractility?cardiac contractility?

It is only “aortic arch pressure” that It is only “aortic arch pressure” that can be used to measure LV can be used to measure LV contractility, not “peripheral contractility, not “peripheral pressure”pressure”

As BP is measured farther into As BP is measured farther into periphery:periphery:

The anacrotic and dicrotic notches disapThe anacrotic and dicrotic notches disappearpear The waveform appears narrowerThe waveform appears narrower The systolic and pulse pressure increaseThe systolic and pulse pressure increase The upstroke becomes steeperThe upstroke becomes steeper The diastolic and mean pressure decreaThe diastolic and mean pressure decreasese

Morphology changes as a result of Morphology changes as a result of peripheral reflexions:peripheral reflexions:

Reflexion of waves due to the tapering diReflexion of waves due to the tapering diameterameter Reflexion due to changing content of the Reflexion due to changing content of the arterial wallarterial wall Reflexion also occur at branching points Reflexion also occur at branching points of vesselsof vessels

Is the arterial waveform predictive Is the arterial waveform predictive of stroke volume?of stroke volume?

The pressure does not predict flowThe pressure does not predict flow The distensible aortic arch act as a “fixeThe distensible aortic arch act as a “fixed-capacity, high pressure reservoir”d-capacity, high pressure reservoir” Flow in the arterial tree is continuous, wiFlow in the arterial tree is continuous, with 10-20 percent of LV power being pulsith 10-20 percent of LV power being pulsitiletile

Cullen et al: Correlation coefficient of Cullen et al: Correlation coefficient of 0.82 between changes in stroke volume 0.82 between changes in stroke volume and changes in peripheral systolic and changes in peripheral systolic pressure in halothane-induced pressure in halothane-induced anesthesia status, where peripheral anesthesia status, where peripheral vascular resistance remained essentially vascular resistance remained essentially unchangedunchanged

Interpretation of blood pressure measurement in anesthesiaInterpretation of blood pressure measurement in anesthesiaAnesthesiology, 40:6 1974Anesthesiology, 40:6 1974

Role of direct arterial pressure Role of direct arterial pressure monitoringmonitoring

Provides trends over a wide rangeProvides trends over a wide range Unreliable as absolute hemodynamic vaUnreliable as absolute hemodynamic valueslues As a reminderAs a reminder ““A needle in an artery does not guarantA needle in an artery does not guarantee a pressure or accuracy any more than ee a pressure or accuracy any more than an endotracheal tube guarantee a patenan endotracheal tube guarantee a patent airway.”t airway.”

Conditions that affect arterial Conditions that affect arterial waveform morphologywaveform morphology

Hyperdynamic pulseHyperdynamic pulse Pulsus paradoxusPulsus paradoxus

Reverse pulsus paradoxus Reverse pulsus paradoxus Pulsus alternansPulsus alternans Pulsus bisferensPulsus bisferens

Hyperdynamic pulseHyperdynamic pulse Aortic regurgitationAortic regurgitation AV fistulaAV fistula ThyrotoxicosisThyrotoxicosis AnemiaAnemia PregnancyPregnancy sepsissepsis

Pulsus paradoxusPulsus paradoxus

Cause of pulsus paradoxusCause of pulsus paradoxus Change in pleural pressure Change in pleural pressure

associated with breathingassociated with breathing Anatomic relationship between two Anatomic relationship between two

ventricle chambersventricle chambers

D/D of Pulsus paradoxusD/D of Pulsus paradoxus Constrictive pericarditis or cardiac tampConstrictive pericarditis or cardiac tamponadeonade COPDCOPD AsthmaAsthma Tension pneumothoraxTension pneumothorax

Reverse pulsus paradoxusReverse pulsus paradoxus An exaggeration of the rise in systolic BP An exaggeration of the rise in systolic BP during mechanical ventilationduring mechanical ventilation A sensitive indicator of hypovolemia in A sensitive indicator of hypovolemia in mechanically ventilated p’tmechanically ventilated p’t

Pulsus alternansPulsus alternans

Cause of pulsus alternansCause of pulsus alternans A sign of decreased myocardial A sign of decreased myocardial

contractility (deletion of the number contractility (deletion of the number of myocardial cells contracting on of myocardial cells contracting on alternate beats)alternate beats)

An alteration in diastolic volume An alteration in diastolic volume leading to beat-to-beat variation in leading to beat-to-beat variation in preload preload

D/D of pulsus alternansD/D of pulsus alternans LV dysfunctionLV dysfunction Pericardial effusion Pericardial effusion

Pulsus bisferensPulsus bisferens

Pulsus bisferensPulsus bisferens Hypertrophic cardiomyopathyHypertrophic cardiomyopathy Aortic regurgitationAortic regurgitation

Advantages and disadvantages Advantages and disadvantages on various cannulation siteson various cannulation sites

Radial artery Radial artery Brachial artery Brachial artery Femoral artery Femoral artery

Axillary arteryAxillary artery Dorsalis pedis arteryDorsalis pedis artery

Radial arteryRadial artery Advantages: easy to cannulate, accessiblAdvantages: easy to cannulate, accessible during most type of surgery, good colle during most type of surgery, good collateral circulation, patient comfort, Allenateral circulation, patient comfort, Allen’s test’s test Disadvantages: thormbus formation, poDisadvantages: thormbus formation, possible injury to nerve, augmentation of Sssible injury to nerve, augmentation of SBP, BP,

Brachial arteryBrachial artery Advantages: easy to cannulate, larger caAdvantages: easy to cannulate, larger catheter, less SBP augmentation, collateratheter, less SBP augmentation, collateral vesselsl vessels Disadvantage: uncomfortable for p’t, Disadvantage: uncomfortable for p’t, median nerve damagemedian nerve damage

Femoral arteryFemoral artery Advantages: prolonged use, useful in shAdvantages: prolonged use, useful in shock p’t, largest catheterock p’t, largest catheter Disadvantages: atherosclerotic plaque Disadvantages: atherosclerotic plaque may break off, massive hematoma, difficmay break off, massive hematoma, difficult to immobilizeult to immobilize

Axillary arteryAxillary artery Advantages: large size, useful in peripheAdvantages: large size, useful in peripheral artery dz and shock, proximity to aortral artery dz and shock, proximity to aorta, a, Disadvantages: neurologic complication,Disadvantages: neurologic complication, technically difficult technically difficult

Dorsalis pedis arteryDorsalis pedis artery Advantages: dual circulationAdvantages: dual circulation Disadvantages: greatest SBP Disadvantages: greatest SBP

augmentation, thrombus formation, augmentation, thrombus formation, difficult to immobilize, impossible to difficult to immobilize, impossible to walkwalk

Take home messageTake home message The arterial system functions as a The arterial system functions as a

damped, resonant, transmission line, damped, resonant, transmission line, transmitting various frequencies with transmitting various frequencies with different degrees of attenuation.different degrees of attenuation.

The clinician must dissuade himself The clinician must dissuade himself from the belief that the peripheral from the belief that the peripheral pressure accurately reflects aortic pressure accurately reflects aortic arch pressure.arch pressure.

referencereference Monitoring in Anesthesia and Critical Care Medicine, 2Monitoring in Anesthesia and Critical Care Medicine, 2nd edition. 1990nd edition. 1990 Hemodynamic monitoring: Invasive and Noninvasive Hemodynamic monitoring: Invasive and Noninvasive Clinical application, 2nd edition.1995Clinical application, 2nd edition.1995 Cullen et al: Interpretation of blood pressure measureCullen et al: Interpretation of blood pressure measurement in anesthesia. Anesthesiology, 40:6 1974ment in anesthesia. Anesthesiology, 40:6 1974

Thanks for your attention!Thanks for your attention!