Critical Care Critical Care Monitoring Monitoring

Nuts and BoltsNuts and Bolts

Mike McEvoy, PhD, REMT-P, RN, CCRNAlbany Medical Center, Albany, New York, USA

Cardiothoracic Surgical ICU

Mike McEvoy, PhD, RN, CCRN, REMT-P

www.mikemcevoy.com

DisclosuresDisclosures• I serve on the speakers bureaus for

Masimo Corp. and Medtronic Corp.• I have no other financial

relationships to disclose.• I am the EMS editor for Fire

Engineering magazine.• I do not intend to discuss any

unlabeled or unapproved uses of drugs or products.

Jones & Bartlett, 2010Jones & Bartlett, 2010

Goals for this talk:Goals for this talk:• Objectives of hemodynamic

monitoring• Blood pressure measurement• Art lines in practice• Preventing complications• Troubleshooting• Treatment parameters/goals• Non-invasive monitoring• New technologies

Goal of hemodynamic Goal of hemodynamic monitoringmonitoring

• Assess tissue perfusion– Oxygenation and distribution (flow)

• Others?– Respirations

– Hydration

– Labs:» Chemistries

» Hematology

» Toxicology

» Microbiology

3 types of shock:3 types of shock:

1. Distributive (septic)

2. Volume (hypovolemic)

3. Pump (cardiogenic)

Are physical findings Are physical findings enough?enough?

• HR

• LOC

• BP

• UO

Apparently not…Apparently not…

• 50% of physical assessments wrong • Therapeutic interventions altered with

invasive assessment 34 - 56% of the time:– 1980 Del Guercio - 1984 Connors – 1984 Eisenberg - 1990 Bailey – 1991 Steinberg - 1993 Coles – 1994 Minoz - 1998 Staudinger – 2002 Jacka

Lung Sounds in HFLung Sounds in HF

• If rales were present, all had a wedge pressure >18, very specific

• Only 9 of 37 with a wedge pressure >18 had rales, very insensitive

• So…clear lung fields tell you very little about fluid status in heart failure

Butman et al. J Amer Coll Cardiol. 10/93

So we dove right in…So we dove right in…

Swan Ganz Catheterization

Connors et al 1996 Connors et al 1996 JAMAJAMA

5734 adult ICU patients 1989-1994, 5 ICUs at 15 tertiary med centers

PA cath = 30 day mortality, ICU LOS, costs of care

Harvey et al: PAC-Man Harvey et al: PAC-Man 2005 Lancet 2005 Lancet - - Game Game Over?Over?

1014 patients at 65 UK institutions:NO DIFFERENCE between PA cath versus no PA cath

Cochrane R & R: 2006 Cochrane R & R: 2006 (Review and Reappraisal)(Review and Reappraisal)

“The PAC is a monitoring tool; if it is used to direct therapy

and there is noimprovement in outcome, then the therapy does not

help.”

Two Problems:Two Problems:

1. Define “normal”

2. Who’s behind the wheel?

Blood Pressure

BP = CO x SVR

Indirect Pressure Measurement Direct Pressure Measurement

** A diastolic pressure of 60 is necessary to maintain coronary artery perfusion.

Why do we measure Why do we measure BP?BP?• Because we can.

Purpose of blood Purpose of blood pressurepressure

Biventricular CV Biventricular CV SystemSystemL (systemic) R (pulmonic)

LV 110/10 RV 25/ 0-5

AO 120/80 PA 25/10

capillary 30-50 capillary 12-17

RA 0-5 LA 8-12

Arterial Pressure Arterial Pressure MonitoringMonitoring

Direct

Pressure

Indirect

Flow

Flow Measurements Flow Measurements Not Accurate:Not Accurate:

• Low blood flow states

• High SVR states– Avg 33.1 mmHg difference

cuff vs. a-line

– Cuff consistently underestimates pressure

- Cohn, JM (JAMA 199:972, 1967)

Flow measurements Flow measurements • Pulses• Cuff• NIBP• Doppler

All sense pulsatile flow

27

What We What We KnowKnow about about FlowFlow

(Indirect Measurement)(Indirect Measurement)• Pulses: – Carotid = SBP > 60– Femoral = SBP > 70– Radial = SBP > 80

• Cuff– Errors in measurement r/t size and heart level

• NIBP– Calculates systolic and diastolic based on MAP and HR

• Doppler– PEA

• Flow based measurements are NOT accurate in low flow states or with high SVR, e.g. shock

Avoid assumptions !Avoid assumptions !

1. BP ≠ blood flow

levophed…

2. Blood flow ≠ perfusion

O2 or nutrient deficiency…

Arterial Pressure Monitoring Indications

Patient in shock not rapidly responsive to therapy

Insertion SitesRadialBrachialAxillaryFemoralDorsalis Pedis

Arterial Pressure Monitoring

Radial artery has the benefit of collateral circulation from the ulnar artery

Allen Test used to evaluate the collateral flow prior to radial artery cannulation

A-line Monitoring Set-up

Invasive Monitoring Equipment

Flush solution -- usually heparinized Continuous flush system (usually a

pressure bag or pump) Pressure transducer and pressure tubing Invasive catheter Monitor

Transducers

Convert one form of energy to another

Sense pressure Convert it to an

electrical signal Electrical signal

causes monitor reading

+

-

Dom e

Leveling, Referencing, Balancing…

Placing the air-fluid interface of the catheter system at the phlebostatic axis

This negates the weight effect of the fluid in the catheter tubing (hydrostatic pressure)

“Setting the correct reference point is the single most important step in setting up a pressure monitoring system.” … Gardner, 1993

Leveling: the # 1 Cause of Error in Pressure Monitoring

Phlebostatic Axis Located at the

intersection of the 4th ICS and midway between the anterior and posterior surfaces of the chest

Midaxillary line is NOT interchangeable with mid anteroposterior level in all persons … Bartz, et al, 1988

Phlebostatic Axis

As the patient moves from flat to upright, the phlebostatic level rotates on the axis and remains horizontal. This position confirmed by CT by Paolella, et al, 1988.

Phlebostatic Axis

The phlebostatic axis moves to midchest at the 4th ICS when patient is in the lateral position.

Leveling

Air fluid interface is the point in the system that is opened to air during zeroing

Inaccuracies are produced if the air-fluid interface is above or below the phlebostatic axis – 1.86 mmHg/inch

Phlebostatic axis determined by Windsor and Burch (1945) as correct reference for measurement of venous pressures

Give 500 ml of LR for CVP < 5 Transducer leveled 2 inches too

high 1.86 mmHg/inch x 2 =

underestimation of actual CVP by 3.72 mmHg (Ooops!)

Recorded CVP = 3 500 cc bolus of LR given Actual CVP = 7 (before LR

bolus)

Zeroing

Opening the system to air to establish atmospheric pressure as zero (0)

This negates all pressure contributions from the atmosphere

Allows only pressure values that exist within the heart or vessel to be measured

When to Zero Before insertion After disconnecting transducer from

pressure cable When values are in question

Ahrens, T. et al. Frequency requirements for zeroing transducers in hemodynamic monitoring, Am J Crit Care, 1995;4:466-471

Arterial Pressure Waveform

1. Systole

2. Dicrotic notch

3. Diastole

Placement of Arterial Placement of Arterial LineLine

150

90

60

MAPMAP

Art Line Placement:Art Line Placement:• The farther out, the higher the SBP• Cuff has no correlation

– Pressure vs. Flow

• Mean Pressure always consistent

If BP increases, does If BP increases, does flow increase?flow increase?

• Think of levophed…

NOPE

Preventing Complications with Arterial Lines

Complication Preventive Measure

Confusion with venous line Clearly label tubing as “Arterial”

Hemorrhage ALARMS, routinely check connectors

Infection Label dressing, careful sampling

Loss of waveform, catheter movement Immobilize extremity, secure catheter to skin

Blood back-up into tubing, loss of waveform

Pressurize system > patient blood pressure

Loss of circulation distal to site ?spasm vs thrombus? - may need to d/c

Clotted Use continuous flush system

Troubleshooting Common Arterial Line Problems

Damping of waveformCauses:

Flush bag empty or pressure < patient pressure Catheter tip against vessel wall Clot at catheter tip Air bubbles in system Kinked catheter or tubing

Troubleshooting Common Arterial Line Problems

Damping of waveform Interventions:

Keep flush bag at 300 mmHg Reposition extremity, use splint if necessary Gently aspirate clot, then flush line Clear system of air bubbles (limit to 1

stopcock) Remove kinks in tubing, check site, consider

suturing catheter to skin

Troubleshooting Common Arterial Line Problems

Abnormally high/low readingsCauses:

Transducer not level Hypertension/hypotension System error

Interventions: Re-level system Assess pressure with alternate means Determine and optimize system dynamic

response

Two Problems:Two Problems:

1. Define “normal”

2. Who’s behind the wheel?

What is “normal”?What is “normal”?

Blood Pressure:

• Bland, ShoemakerJ Surg Obst 1978 -– 74 % of survivors

achieved normal values– 76% of NON-

SURVIVORS achieved normal vital signs

Is it the car or the Is it the car or the driver?driver?• If you don’t know how to drive, a car can be a dangerous weapon.

• If you don’t know how to interpret the data, a monitoring catheter can be a dangerous weapon.

What we really treat:What we really treat:NL Treat

HR 60 – 100 < 40 or > 120

MAP 70 – 105 < 60 – 70

CVP 2 – 6 < 5, Panic > 20

Sa02 95 – 100% < 90

ScvO2 > 70% (sepsis) <70% if hct >30

CI 2.5 – 4.0 < 2.2 – 2.5

SI 25 - 45 < 25 concerns you

Lactate 1 – 2 > 4 mmol/L and pH < 7.30 suggests tissue hypoxia

pH 7.35 – 7.45 Hmmm… 6.888, BE + 5…

Critical Information

• Oxygenation

• Perfusion

Evaluating PerfusionEvaluating Perfusion• Tools we have

Lactate (Lactic Acid)Lactate (Lactic Acid)

Hypoperfusion severity index

NL < 2, concerned when > 4

> 15 often fatal

More helpful as trend

POC Lactate TestingPOC Lactate Testing

• Developed for athletes & climbers

• Not FDA approved

• Currently underinvestigation in EMSand Fire service

SvOSvO22

• Reflects O2 reserve & extraction

• < 60% requires investigation:– Hct, CO, SaO2

– VO2

• The lower the level, the worse…

• < 40% typically fatal

ScvOScvO22

• O2 reserve & extraction upper body

• Typically 5 – 13% > SvO2 (avg 7.5)

• NL > 70%

• Sampled from CVC (oximetric CVL available)

Gastric Mucosal COGastric Mucosal CO22

• Recent data suggest PgCO2 may reflect perfusion

• CO2 clearance reflects perfusion

• A-g CO2 gap < 10 is normal

• Pa CO2 - PgCO2 gap > 10 is bad

Sublingual COSublingual CO22 – PslCO – PslCO22 Very proximal gut

NL = 44 – 64 mmHg

levels correlate with perfusion

Studies halted August 2004

Nellcor Capnoprobe™ Nellcor Capnoprobe™ US approval Jan 2003.

Research study: Children's Medical Center – Dallas TX.

11 kids infected Burkholderia cepacia, 2 died.

Traced to saline solution packaging of probes.

5,600 units @ 30 centers recalled

CapnographyCapnography

• CO2 clearance reflects perfusion!

• Available for intubated and non-intubated patients

• Developmentscoming: IPI

Decision to Call the Decision to Call the CodeCode• 120 prehospital patients in

nontraumatic cardiac arrest

• EtCO2 had 90% sensitivity in predicting ROSC

• Maximal level of <10mmHg during the first 20 minutes after intubation was never associated with ROSC

Source: Canitneau J. P. 1996. End-tidal carbon dioxide during cardiopulmonary resuscitation in humans presenting mostly with asystole, Critical Care Medicine 24: 791-796

End-tidal COEnd-tidal CO22 (EtCO (EtCO22))

Normal a-A gradient– 2-5mmHg difference between the EtCO2

and PaCO2 in a patient with healthy lungs

– Wider differences found » In abnormal perfusion and ventilation » Incomplete alveolar emptying» Poor sampling

Future DevelopmentsFuture Developments

• Perfusion assessment derived from exhaled CO coupled with bioimpedance data.

Integrated Pulmonary Integrated Pulmonary IndexIndex™™

IPI Values – fuzzy logicIPI Values – fuzzy logic

IPI Patient Status10 Normal

8-9 Within normal range

7 Close to normal range; requires attention

5-6 Requires attention

3-4 Requires attention or intervention

1-2 Requires intervention

Acoustic Resp Acoustic Resp MonitoringMonitoring• Likely release 2010

• Electrical sensor based• Initially will report RR

• Future versions VT

• Telemetry based• May replace capnography?

Esophageal doppler Esophageal doppler (TED)(TED) Transducer probe inserted into distal esophagus

Blood flow measured by doppler principle

TTE (Trans Thoracic TTE (Trans Thoracic Echo)Echo)• Also nurse or medic driven

• Chest wall instead of esophageal

TED/TTE:TED/TTE:

Bioimpedance (TEB)Bioimpedance (TEB)

• Thoracic electrical bioimpedance

• 4 electrodes sent current through thorax, analyze flow resistance

• With age, gender, height, weight calculate SV, ejection time, CO, thoracic fluid content, acceleration index, velocity index, etc.

TEB (CardioDynamics TEB (CardioDynamics BioZBioZ®®))

RELIANT RELIANT Non Invasive Hemodynamic MonitorNon Invasive Hemodynamic Monitor

SVR MAP-CVP / CO

CO Cardiac Output

CI Cardiac Index

SV Stoke Volume

SVV Stroke Volume Variance

SVI Stroke Volume Index

HR Heart Rate

TPR Total Peripheral Resistance

VET Ventricular Ejection Time

MAP Mean Arterial Pressure

NIBP Non Invasive Blood Pressure

TFC Thoracic Fluid Content

TFCd % Directional Change in TFC/Time

CP Cardiac Power

CPI Cardiac Power Index

CAPTURES (14 ) PARAMETERSCAPTURES (14 ) PARAMETERS“In Real Time”“In Real Time”

TPR : Dynes – (MAP / CO)*80 TPR : mmHg * min./liters – (MAP / CO)

TFCd : % Change in TFC over 15 mins. Vs. baseline TFC CP: MAP*CO/451

CPI: CP/BSA

Current of a known amplitude & frequency is applied on outer electrodes

Voltage signal captured on inner electrodes

100% Noninvasive100% NoninvasiveMonitors Any Patient, AnywhereMonitors Any Patient, Anywhere

Change in phase of the frequency is recorded and the signal translated to flow (similar to Doppler in concept)

0 I

II

II

I

Volts

Io

Vo

Io

Vo

0 I

II

II

I

Amp.

Bioimpedance

Bioreactance

PASSIVE LEG RAISE TEST (PLRT)PASSIVE LEG RAISE TEST (PLRT)

12%12%

FLUIDFLUIDRESPONSIVERESPONSIVE

12%12%

NOT FLUIDNOT FLUIDRESPONSIVERESPONSIVE

3 MINS. BASE LINE CO/CI

11

VENOUS BLOOD SHIFT

BEFORE PLRBEFORE PLR DURING PLRDURING PLR3 MINS. CO/CI POST SHIFT

22

CO & CI IMPACTCO & CI IMPACT

• Volume expansion 1st line of therapy.

• Only ½ of patients respond to fluids with increased CO.

• Need a reliable means to determine ability to respond to fluid.

Problem: Enough Volume? Problem: Enough Volume?

Chest 2002;121;1245-1252

PLR?? PLR?? Passive

Leg Raising45 °

Semi-Fowler’s Passive

Leg Raising45 °

Semi-Fowler’s

• 150 – 300 ml volume• Effects < 30 sec.. Not more than 4 minutes• Self-volume challenge• Reversible

Ocular ScannerOcular Scanner

EyeMarker Systems™

Retinal imagingRetinal imaging• Pattern

recognition:– Botulism,

neurotoxins– Nerve Agents– Carbon Monoxide– Cyanide

Hydration StatusHydration Status

• Saliva osmolality

Perfusion IndexPerfusion Index• Perfusion Index is an objective method for

measuring a patient’s peripheral perfusion• Perfusion Index is an early indicator of

deterioration

Perfusion IndexPerfusion Index

Infrared

Saturation

Red

• 108 healthy, 37 critically ill adults (finger sensors)

• PI range: 0.3% to 10%, median 1.4%

• ROC used to determine the “cutoff” value

• 1.4% PI best discriminated normal from abnormal

What is a “Normal” PI ?What is a “Normal” PI ?

Lima, et al. CCM 2002

Clinical Uses for PI Normals have been suggested to be:

>1.4% adults, >1.27% neonates1.Site selection (varies between patients and sites)2.Chorioamnionitis (placental membrane/amniotic

fluid infection)3.Effectiveness of Servoflorane anesthesia4.Monitor onset/effectiveness of epidural anesthesia5.Predict illness severity scores (good correlation)6.Monitor/quantify peripheral perfusion7.Detect shock states

8.PI trend may best reflect changes in condition

PhotoplethysmographyPhotoplethysmography

Abs

orpt

ion

TimeTime

R IR

Photodetector

Pleth Waveform

Pleth WaveformPleth Waveform

A-line versus Pulse Ox Pleth

Definition of PVIDefinition of PVI• Pleth Variability Index (PVI) is a

measure of dynamic changes in PI that occur during the respiratory cycle

• PVI is a percentage from 1 to 100%: 1 = no variability and 100 = maximum variability

Fluid Status/Volume Responsiveness

• High variability (high PVI) = volume depletion

• 15 – 50% of patients are fluid non-responders – low variability (low PI) suggests the patient is a non-responder– The ventricle more sensitive to respiratory

changes is more responsive to preload

Pulse CO-Oximetry

Oxygenated Hb and reduced Hb absorb different amounts of Red (RD) and Infrared (IR) Light

Pulse CO-Oximetry

Oxygenated Hb and reduced Hb absorb different amounts of Red (RD) and Infrared (IR) Light

1. Carboxyhemoglobin

2. Methemoglobin

3. Hemoglobin

4. ? Glucose

5. ? Cyanide

6. ?

SummarySummary

• Perfusion is the goal

• Perfusion = oxygenation + flow

• You cannot do it alone

• Less invasive is better

• Technology should make you a better clinician (only as good as u)

Thanks for your Thanks for your attention!attention!