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CARDIAC MONITORING & RHYTHM RECOGNITION

CARDIAC MONITORING & RHYTHM RECOGNITION. How to monitor the ECG (1): Monitoring leads. 3-lead system approximates to I, II, III Colour coded Remove hair Apply over bone Lead setting (II) Gain. How to monitor the ECG (2): Defibrillator paddles. Suitable for “quick-look” Movement artefact

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CARDIAC MONITORING & RHYTHM RECOGNITION

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  1. CARDIAC MONITORING &RHYTHM RECOGNITION

  2. How to monitor the ECG (1):Monitoring leads • 3-lead system approximates to I, II, III • Colour coded • Remove hair • Apply over bone • Lead setting (II) • Gain

  3. How to monitor the ECG (2):Defibrillator paddles • Suitable for “quick-look” • Movement artefact • Risk of spurious asystole

  4. How to monitor the ECG (3):Adhesive monitoring electrodes • “Hands-free” monitoring and defibrillation

  5. Basic electrocardiography (1) • Depolarisation initiated in SA node • Slow conduction through AV node • Rapid conduction through Purkinje fibres

  6. Basic electrocardiography (2) • P wave = atrial depolarisation • QRS = ventricular depolarisation (< 0.12 s) • T wave = ventricular repolarisation

  7. Cardiac arrest rhythms • Ventricular fibrillation • Pulseless ventricular tachycardia • Asystole • Pulseless Electrical Activity (PEA)

  8. Ventricular fibrillation • Bizarre irregular waveform • No recognisable QRS complexes • Random frequency and amplitude • Unco-ordinated electrical activity • Exclude artifact • movement • electrical interference

  9. Pulseless ventricular tachycardia • Broad regular complex rhythm • Rapid rate 100-300 per min • Constant QRS morphology • Atrial activity continues independently

  10. Asystole • Absent ventricular (QRS) activity • Atrial activity (P waves) may persist • Rarely a straight line trace

  11. Pulseless Electrical Activity • Clinical absence of cardiac output despite electrical activity • ECG is normal or near normal

  12. DEFIBRILLATION

  13. Mechanism of defibrillation • Definition “The termination of fibrillation or absence of VF/VT at 5 seconds after shock delivery” • Critical mass of myocardium depolarised • Natural pacemaker tissue resumes control

  14. Defibrillation Success depends on delivery of current to the myocardium Current flow depends upon: • Electrode position • Transthoracic impedance • Energy delivered • Body size

  15. Transthoracic Impedance Dependent upon: • Electrode size • Electrode/skin interface • Contact pressure • Phase of respiration • Sequential shocks

  16. Defibrillators • Design • Power source • Capacitor • Electrodes • Types • Manual (monophasic or Biphasic waveform) • Automated

  17. Defibrillator waveforms • Damped Monophasic • Truncated Biphasic

  18. Biphasic Defibrillators • Require less energy for defibrillation • smaller capacitors and batteries • lighter and more transportable • Repeated < 200 J biphasic shocks have higher success rate for terminating VF/VT than escalating monophasic shocks

  19. Automated external defibrillators • Analyse cardiac rhythm • Prepare for shock delivery • Specificity for recognition of shockable rhythm close to 100%

  20. Automated external defibrillators Advantages: • Less training required • no need for ECG interpretation • Suitable for “first-responder” defibrillation • Public access defibrillation (PAD) programs

  21. 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

  22. ANALYSING RHYTHM DO NOT TOUCH VICTIM SHOCK INDICATED • Stand clear • Deliver shock STOP !!!DEFIBRILLATIONApproach safely

  23. SHOCK DELIVEREDFOLLOW AED INSTRUCTIONS or NO SHOCK ADVISEDFOLLOW AED INSTRUCTIONS Deliver CPR 30:2 !! IF VICTIM STARTS TO BREATHE NORMALLY PLACE IN RECOVERY POSITION

  24. Adult CPR techniques can be used on children Compressions 1/3 of the depth of the chest CPR IN CHILDREN

  25. 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

  26. Manual Defibrillation Relies upon: • Operator recognition of ECG rhythm • Operator charging machine and delivering shock • Can be used for synchronisedcardioversion

  27. Defibrillator Safety • Never hold both paddles in one hand • Charge only with paddles on casualty’s chest • Avoid direct or indirect contact • Wipe any water from the patient’s chest • Remove high-flow oxygen from zone of defibrillation

  28. Shock Energy MONOPHASIC • Initial and subsequent shocks energy 360 J*, repeat once if unsuccessful • Deliver shocks singly BIPHASIC • Initial shock 150-200 J • Subsequent shocks 200-360 J • If defibrillation restores the patient’s circulation and VF/VT recurs, start again at 150J*

  29. Manual Defibrillation • Diagnose VF/VT from ECG and signs of cardiac arrest • Select correct energy level • Charge paddles on patient • Shout “stand clear” • Visual check of area • Check monitor • Deliver shock

  30. Call Resuscitation Team OpenAirway Look for signs of life Unresponsive ? CPR 30:2 Untildefibrillator / monitor attached Assess Rhythm Shockable (VF/Pulsless VT) Non-shockable (PEA/Asystole) 1 Shock 150-360 J biphasic lub 360 J monophasic Immediately resume: CPR 30:2 For 2 min Immediately resume: CPR 30:2 For 2 min

  31. Pulseless VT is treated with an unsynchronised shock using the VF protocol

  32. Summary • Defibrillation is the only effective means of restoring cardiac output for the patient in VF or pulseless VT • Defibrillation must be performed promptly, efficiently and safely • New technology has improved machine performance and simplified use

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