CARDIAC MONITORING CARDIAC MONITORING &&

RHYTHM RECOGNITIONRHYTHM RECOGNITION

How to monitor the ECG (1):How to monitor the ECG (1):Monitoring leadsMonitoring leads

• 3-lead system approximates to I, II, III3-lead system approximates to I, II, III• Colour codedColour coded• Remove hairRemove hair• Apply over boneApply over bone• Lead setting (II)Lead setting (II)• GainGain

How to monitor the ECG (2):How to monitor the ECG (2):Defibrillator paddlesDefibrillator paddles

• Suitable for “quick-look”Suitable for “quick-look”• Movement artefactMovement artefact• Risk of spurious asystoleRisk of spurious asystole

How to monitor the ECG (3):How to monitor the ECG (3):Adhesive monitoring electrodesAdhesive monitoring electrodes

• ““Hands-free” monitoring and Hands-free” monitoring and defibrillationdefibrillation

• Depolarisation initiated in SA nodeDepolarisation initiated in SA node• Slow conduction through AV nodeSlow conduction through AV node• Rapid conduction through Purkinje fibres Rapid conduction through Purkinje fibres

Basic electrocardiography (1)Basic electrocardiography (1)

Basic electrocardiography (2)Basic electrocardiography (2)

• P wave = atrial depolarisationP wave = atrial depolarisation• QRS = ventricular depolarisation (< 0.12 s)QRS = ventricular depolarisation (< 0.12 s)• T wave = ventricular repolarisationT wave = ventricular repolarisation

Cardiac arrest rhythmsCardiac arrest rhythms

• Ventricular fibrillationVentricular fibrillation

• Pulseless ventricular tachycardiaPulseless ventricular tachycardia

• AsystoleAsystole

• Pulseless Electrical Activity (PEA)Pulseless Electrical Activity (PEA)

Ventricular fibrillationVentricular fibrillation• Bizarre irregular waveformBizarre irregular waveform• No recognisable QRS complexesNo recognisable QRS complexes• Random frequency and amplitudeRandom frequency and amplitude• Unco-ordinated electrical activityUnco-ordinated electrical activity• Exclude artifact Exclude artifact

– movementmovement– electrical interferenceelectrical interference

Pulseless ventricular tachycardiaPulseless ventricular tachycardia

• Broad Broad regular regular complex rhythmcomplex rhythm• Rapid rateRapid rate 100-300 per min 100-300 per min• Constant QRS morphologyConstant QRS morphology• Atrial activity continues independentlyAtrial activity continues independently

AsystoleAsystole

• Absent ventricular (QRS) activityAbsent ventricular (QRS) activity

• Atrial activity (P waves) may persistAtrial activity (P waves) may persist

• Rarely a straight line traceRarely a straight line trace

Pulseless Electrical ActivityPulseless Electrical Activity

• Clinical absence of cardiac output Clinical absence of cardiac output despite electrical activitydespite electrical activity

• ECG ECG is normal or near normalis normal or near normal

DEFIBRILLATIONDEFIBRILLATION

Mechanism of defibrillationMechanism of defibrillation

• DefinitionDefinition““The termination of fibrillation or absence of The termination of fibrillation or absence of

VF/VT at 5 seconds after shock delivery”VF/VT at 5 seconds after shock delivery”

• Critical mass of myocardium depolarisedCritical mass of myocardium depolarised• Natural pacemaker tissue resumes controlNatural pacemaker tissue resumes control

DefibrillationDefibrillation

Success depends on delivery of Success depends on delivery of current to the myocardiumcurrent to the myocardium

Current flow depends upon:Current flow depends upon:

• Electrode position Electrode position

• Transthoracic impedanceTransthoracic impedance

• Energy deliveredEnergy delivered

• Body sizeBody size

Transthoracic ImpedanceTransthoracic Impedance

Dependent upon:Dependent upon:

• Electrode sizeElectrode size

• Electrode/skin interfaceElectrode/skin interface

• Contact pressureContact pressure

• Phase of respirationPhase of respiration

• Sequential shocks Sequential shocks

DefibrillatorsDefibrillators

• DesignDesign– Power sourcePower source– CapacitorCapacitor– ElectrodesElectrodes

• TypesTypes– ManualManual (m (monophasic or Biphasic waveformonophasic or Biphasic waveform))– AutomatedAutomated

Defibrillator waveformsDefibrillator waveforms

•Damped Monophasic

•Truncated Biphasic

Biphasic DefibrillatorsBiphasic Defibrillators

• Require less energy for defibrillationRequire less energy for defibrillation– smaller capacitors and batteriessmaller capacitors and batteries– lighter and more transportablelighter and more transportable

• Repeated < 200 J biphasic shocks Repeated < 200 J biphasic shocks have higher success rate for have higher success rate for terminating VF/VT than escalating terminating VF/VT than escalating monophasic shocksmonophasic shocks

Automated external defibrillatorsAutomated external defibrillators

• Analyse cardiac rhythmAnalyse cardiac rhythm• Prepare for shock deliveryPrepare for shock delivery• Specificity for recognition of Specificity for recognition of

shockable rhythm close to 100%shockable rhythm close to 100%

Automated external defibrillatorsAutomated external defibrillators

Advantages:Advantages:• Less training requiredLess training required

– no need for ECG interpretation no need for ECG interpretation

• Suitable for “first-responder” defibrillationSuitable for “first-responder” defibrillation• Public access defibrillation (PAD) programsPublic access defibrillation (PAD) programs

SWITCH ON AED

• Some AEDs will automatically switch themselves on when the lid is opened

ATTACH PADS TO CASUALTY’S BARE CHEST

ATTACH PADS TO CASUALTY’S BARE CHEST

ANALYSING RHYTHM DO NOT TOUCH VICTIM

SHOCK INDICATED

• Stand clear• Deliver shock

STOP !!!DEFIBRILLATIONApproach safely

SHOCK DELIVEREDFOLLOW AED INSTRUCTIONS

Deliver CPR 30:2 !!

NO SHOCK ADVISEDFOLLOW AED INSTRUCTIONS

or

IF VICTIM STARTS TO BREATHE NORMALLY PLACE IN RECOVERY POSITION

CPR IN CHILDREN

• Adult CPR techniques can be used on children

• Compressions 1/3 of the depth of the chest

AED IN CHILDREN

• Age > 8 years• use adult AED

• Age 1-8 years• use paediatric pads / settings if available (otherwise use adult

mode)

• Age < 1 year• use only if manufacturer instructions indicate it is safe

Manual DefibrillationManual Defibrillation

Relies upon:Relies upon:• Operator recognition of ECG rhythmOperator recognition of ECG rhythm• Operator charging machine and delivering Operator charging machine and delivering

shockshock• Can be used for synchronised Can be used for synchronised

cardioversioncardioversion

Defibrillator SafetyDefibrillator Safety

• Never hold both paddles in one handNever hold both paddles in one hand• Charge only with paddles on Charge only with paddles on

casualty’s chestcasualty’s chest• Avoid direct or indirect contact Avoid direct or indirect contact • Wipe any water from the patient’s Wipe any water from the patient’s

chestchest• Remove high-flow oxygen from zone Remove high-flow oxygen from zone

of defibrillation of defibrillation

Shock EnergyShock Energy

MONOPHASICMONOPHASIC• Initial Initial and subsequent and subsequent shockshockss energy energy 360360

J*, repeat once if unsuccessful J*, repeat once if unsuccessful • Deliver shocks singlyDeliver shocks singlyBIPHASICBIPHASIC• Initial shock 150-200 JInitial shock 150-200 J• Subsequent shocks 200-360 JSubsequent shocks 200-360 J• If defibrillation restores the patient’s If defibrillation restores the patient’s

circulation and VF/VT recurs, start again at circulation and VF/VT recurs, start again at 150150J*J*

Manual DefibrillationManual Defibrillation

• Diagnose VF/VT from ECG Diagnose VF/VT from ECG andand signs of signs of cardiac arrestcardiac arrest

• Select correct energy levelSelect correct energy level

• Charge paddles on patientCharge paddles on patient

• Shout “stand clear”Shout “stand clear”

• Visual check of areaVisual check of area

• Check monitorCheck monitor

• Deliver shockDeliver shock

CPR 30:2Until defibrillator / monitor attached

AssessRhythm

Shockable(VF/ Pulsless VT)

Non-shockable(PEA / Asystole)

1 Shock150-360 J biphasic

lub 360 J monophasic

Immediately resume:

CPR 30:2 For 2 min

CallResuscitationTeam

Immediately resume:

CPR 30:2For 2 min

Open AirwayLook for signs of life

Unresponsive ?

Pulseless VT is treated with an Pulseless VT is treated with an

unsynchronised shock usingunsynchronised shock using

the VF protocolthe VF protocol

SummarySummary

• Defibrillation is the only effective Defibrillation is the only effective means of restoring cardiac output for means of restoring cardiac output for the patient in VF or pulseless VTthe patient in VF or pulseless VT

• Defibrillation must be performed Defibrillation must be performed promptly, efficiently and safelypromptly, efficiently and safely

• New technology has improved New technology has improved machine performance and simplified machine performance and simplified useuse