Cardiac Arrhythmias & Drugs used in Advanced Life Support and Cardiac Emergencies

Transcription

1 Cardiac Arrhythmias & Drugs used in Advanced Life Support and Cardiac Emergencies CNHE Ballarat Health Services Valid from 1 st March 2016 to 31 st June

2 Supraventricular Tachycardia (SVT) An atrial ectopic focus continuously discharges at rapid rate ECG Recognition: ventricular rate > 150 rhythm - regular P wave early, distorted or may be hidden PR interval usually shorter QRS - narrow T wave - upright 2

3 Supraventricular Tachycardia 3

4 Tachyarrhythmia Algorithm 4

5 Supraventricular Tachycardia If stable Valsalva manoeuvre Carotid sinus massage (Medical procedure) Treat cause Correct electrolytes Adenosine 6mg + 12mg + 12mg Other drugs Amiodarone 300mg over 20mins Beta-blockers If unstable (cardiovascularly compromised) Immediate synchronized cardioversion 5

6 Heart Block Caused by defect in the conduction system, resulting in a delay in conduction through the AV node and Bundle Branches. Common Causes: Ischaemia Infarction (inferior Vs anterior) Carditis Digoxin toxicity Degenerative heart disease Other drugs 6

7 Types of Heart Block Each degree of block indicates a more ischaemic and lower functioning conduction system First degree Second degree (Mobitz) Type I (Wenckebach) (Mobitz) Type 2 Third degree (Complete heart block) 7

8 1st Degree Heart Block A delay in conduction through the AV junction ECG Recognition: rate - variable rhythm - regular P wave - normal PR interval > 0.20 sec QRS - narrow T wave - normal 8

9 1st degree Heart Block 9

10 2nd Degree Heart Block Type I Conduction through AV node is progressively delayed until an atrial impulse is not conducted. This will occur in a sequential pattern. ECG Recognition: rate - variable rhythm - irregular (Wenckebach footprints) P wave - present PR interval - increases until non conduction RR interval - decreases until dropped beat QRS - narrow T wave - normal 10

11 2nd degree Heart Block Type I 11

12 2nd Degree Heart Block Type II Intermittent block of atrial conduction characterised by P wave not conducted. ECG Recognition: rate - variable but usually slow rhythm - irregular P wave - present PR interval constant with each conducted beat RR - interval normal QRS usually narrow T wave - normal 12

13 2nd Degree Heart Block Type 2 13

14 3rd Degree Heart Block No impulses conducted through AV node. AV dissociation - atria and ventricle conduct independently. ECG Recognition: rate < 60 rhythm - atrial rate regular, ventricular rate regular P wave - present PR interval variable with no relationship to the QRS QRS depends on site of escape usually > 0.12 sec T wave - normal 14

15 3rd Degree Heart Block 15

16 Heart Block Treatment Considerations: Oxygen if below 95% Rule out drug toxicity e.g. digoxin, beta blockers, calcium channel blockers Treat cause Continuous monitoring Correct electrolyte imbalances e.g. K +, Mg ++ Atropine 500mcg mg bolus (max 3mg) Adrenaline mcg bolus may be considered at BHS Adrenaline infusion may be required Isoprenaline infusion may be considered External/Temporary/Permanent pacing 16

17 Bradyarrhythmia Algorithm 17

18 Idioventricular Rhythm Ventricular initiated contraction = rate < 60 No visible P waves QRS > 0.12 secs - broad Regular T wave opposite polarity When the rate is it is referred to as Accelerated Idioventricular Rhythm 18

19 Idioventricular Rhythm Clinical Significance: If stable investigate and treat as necessary If unstable i.e. haemodynamic compromise Atropine 500mcg mg bolus Isoprenaline 20mcg bolus &/or infusion Adrenaline 50mcg bolus &/or infusion 19

20 Idioventricular Rhythm 20

21 Ventricular Ectopics Ectopic focus in the ventricular muscle discharges prior to the SA node ECG Recognition: rate - variable rhythm - irregular P wave usually lost PR interval absent QRS > 0.12 sec T wave - opposite polarity EARLY wide bizarre beat 21

22 Pattern of Ventricular Ectopics Unifocal - VEs look the same as each other as they originate from a similar focus Multifocal - VEs look different to each other as they come from different foci Bigeminy - every second beat is an ectopic Trigeminy - every third beat is an ectopic Salvos - paired VEs VT (Ventricular Tachycardia) - 3 or more VEs 22

23 Ventricular Ectopics Uniform ventricular ectopic beats Multiform ventricular ectopic beats 23

24 Ventricular Ectopics Causes: Normal, fatigue, alcohol, caffeine, smoking Myocardial infections - endocarditis Electrolyte disturbances (hyperkalaemia or hypokalaemia) Acute Coronary Syndrome Drug overdose (digoxin, tricyclic antidepressants) Clinical Significance: Hypotension depends on cause, rate, type and number of ectopics Potential for R on T phenomena 24

25 Ventricular Ectopics Treatment: Depends on cause and if patient is symptomatic Oxygen Drug therapy e.g. antiarrhythmic Electrolyte replacement 25

26 Ventricular Tachycardia Consists of 3 or more Ventricular Ectopics Ectopic focus in the ventricular muscle discharges at a rate greater than 110 per minute ECG Recognition: rate > 110 rhythm - regular P - absent QRS > 0.12 sec, broad T wave - opposite in polarity to the QRS complex often occurs following R on T 26

27 Ventricular Tachycardia Causes: Same as ventricular ectopic beats Prolonged QT interval - Torsades de pointes Clinical Significance: Hypotension depends on rate and number of ectopics Hence, patient may be conscious or unconscious May deteriorate to other arrhythmia's e.g. Ventricular fibrillation 27

28 Ventricular Tachycardia Stable May be self limiting treat cause Oxygen if SaO2 below 95% correct electrolytes suppress ectopic focus with antiarrhythmics eg Amiodarone 300mg over 20 mins Or Lignocaine mg/kg synchronised cardioversion Unstable (cardiovascularly compromised) Immediate synchronized cardioversion Pulseless Treat as per ALS algorithm 28

29 Ventricular Tachycardia 29

30 Torsades de Pointes Polymorphic type of Ventricular Tachycardia which is associated with prolonged QT interval (delayed repolarization) The QRS appears positive and negative, with some degree of regularity 30

31 Torsades de Pointes ECG Recognition: rate > 110 rhythm irregular P absent PR interval absent QRS > 0.12 sec, broad T wave opposite in polarity QRS twists on axis 31

32 Torsades de Pointes Causes: Prolonged QT (congenital or drug induced) Acute Coronary Syndrome Drugs - amiodarone, quinidine 32

33 Torsades de Pointes Clinical Significance: May deteriorate into other arrhythmias e.g. Ventricular Fibrillation May be paroxysmal in nature Haemodynamic stability will be short lived Treatment: Defibrillation & BLS Treat cause Magnesium 5mmol bolus, can repeat once Avoid drug therapy that may prolong the QT e.g. amiodarone 33

34 Torsades de Pointes 34

35 Ventricular Fibrillation Several ectopic foci in the ventricles fire rapidly and chaotically No discernable QRS complexes, ventricular muscle contraction uncoordinated and chaotic = no C.O. = brain not being perfused = always unconscious 35

36 Ventricular Fibrillation ECG recognition: bizarre configuration No recognisable QRS 36

37 Ventricular Fibrillation 37

38 VF / Pulseless VT management BLS if defibrillator not immediately available The only initial effective treatment for VF and pulseless VT is DEFIBRILLATION 38

39 Asystole No electrical activity in the heart. No recognisable complexes on ECG No cardiac output. Confirming Asystole: If ECG looks like an isoelectric flat/wandering line, check your patient, try changing monitoring lead and increase the amplitude of the lead This will aid differentiation between asystole and fine ventricular fibrillation 39

40 Asystole Treatment: BLS Identify and treat reversible causes Drugs: Adrenaline 1mg repeat every 4 mins Electrolyte replacement Consider pacing 40

41 Asystole 41

42 Pulseless Electrical Activity (PEA) There is electrical activity with no cardiac output. ECG Recognition: rate & rhythm variable P wave, PR interval, QRS, and T wave may all be normal 42

43 Pulseless Electrical Activity (PEA) Treatment: BLS Identify and treat cause fluid replacement if hypovolaemic Drugs: Adrenaline 1mg every 4 mins Consider electrolyte replacement Consider pacing 43

44 Ventricular Standstill Atrial activity with no ventricular activity. ECG Recognition: Ventricular activity absent P waves normal No QRS complex s or T waves 44

45 Ventricular Standstill Treatment: BLS treat cause drug therapy adrenaline electrolyte replacement emergency pacing 45

46 Ventricular Standstill 46

47 Resuscitation Drugs 47

48 Resuscitation Drugs Not shown to improve survival Good quality CPR, Defibrillation are the priorities IV preferable peripheral, jugular, avoid lower limbs IV admin. followed by 20 ml flush and CPR for 2 minutes Administer via a CVC if available Intraosseous if 2 attempts to cannulate or 1 attempt in children 48

49 ETT administration De-emphasized by the ARC. I/O is the preferred method if IV access not possible. Technique suction airway insert clear catheter e.g Y suction dilute drug in 10 ml Water for Injection dose 2-3 times normal IV dose flush with 20mls N/Saline follow with 2 vigorous inflations Adrenaline, lignocaine and atropine are the only drugs that may be administered via the ETT in ALS NEVER give drugs via a Laryngeal Mask Airway 49

50 ETT administration Water for Injection 50

51 Drugs of ALS Adrenaline Amiodarone Atropine (not for use in Asystole/ PEA) Lignocaine Potassium Magnesium 51

52 Adrenaline Natural catecholamine alpha - peripheral effects beta 1 & 2 - cardiac & bronchial effect Role in ALS most important drug of ALS vasoconstriction directs blood to heart / brain increases aortic root pressure facilitates defibrillation by improving myocardial blood flow and reducing acidosis 52

53 Adrenaline Indications: VF / pulseless VT after defibrillation has failed Asystole / PEA initial treatment Complications: tachycardia hypertension Dosage: 1 mg initially (if no cardiac output) Repeated 4 minutely No maximum dose Post resuscitation if bradycardic & hypotensive may need to administer increments of 50mcg &/or preferably commence an infusion 53

54 Action: Amiodarone Depresses SA node and slows AV conduction increases repolarisation lowers defibrillation threshold restores fibrillation threshold Indications: First line antiarrhythmic of choice in VF/VT If defibrillation & adrenaline failed to revert VF/VT Atrial tachyarrhythmias SVT, WPW, Rapid AF/Aflutter 54

55 Amiodarone Dosage: 300mg bolus diluted up to 20 mls 5% Glucose over 1 min Incompatible with 0.9% Saline Can repeat bolus at 150mg Infusion 15mg/kg over 24 hours Complications: Hypotension prolonged QT Heart blocks Bradycardia 55

56 Atropine Action: Parasympathetic antagonist that suppresses vagus nerve activity Indications: symptomatic bradyarrhythmias Dosage: 1 mg bolus in severe bradycardia Can be repeated up to a maximum of 3mg Complications: Tachycardia Dilated pupils and dry mouth 56

57 Action: Lignocaine Membrane stabilising antiarrhythmic drug Indications: Monomorphic VT If defibrillation & adrenaline failed to revert pulseless VT If IV route unavailable and ETT route only available Complications: CNS: drowsiness, agitation, fitting hypotension, bradycardia, heart block increases defibrillation threshold Dosage: mg/ kg slow IV bolus repeat at half the dose if required 57

58 Action: Potassium Chloride An electrolyte required for membrane stability Decreased K+ leads to arrhythmias Indications: VT / VF where low potassium suspected Dosage: 5 mmol IV diluted to 20mls Complications: hyperkalaemia - bradycardia, asystole tissue necrosis 58

59 Magnesium Sulphate Action: Electrolyte essential for membrane stability Indications: Torsades des pointes Cardiac arrest/arrhythmias associated with Digoxin Toxicity VF/pulseless VT Hypokalaemia or hypomagnesium 59

60 Magnesium Sulphate Dosage: 5 mmol bolus Can repeat 5mmol bolus once Infusion of 20mmol over 2 hours Complications: muscle weakness Hypotension paralysis respiratory failure bradycardia 60

61 Sodium bicarbonate Action: Alkalising solution used to reverse the acidosis of hypoxia and cardiac arrest Indications: NOT FOR ROUTINE USE IN RESUSCITATION OD tricyclic antidepressants 61

62 Sodium bicarbonate Dosage: bolus 1 mmol / kg over 2-3 minutes adequate CPR and ventilation (ETT) is essential for effective stabilisation of ph in conjunction as a priority over - sodium bicarbonate Complications: Intracellular acidosis risk of alkalosis, hypernatreamia rebound acidosis as CO 2 liberated from HCO 3 62

63 Additional drugs used in cardiac emergencies Adenosine Isoprenaline Calcium 63

64 Action Adenosine Slows sinus node rate prolongs AV conduction, causing high grade block half life < 5 secs Indications: treatment SVT diagnosis of Atrial flutter Atrial fibrillation broad complex tachycardia (where VT is unlikely) 64

65 Adenosine Dosage; 6mg IV quickly, then if required 12mg and if required repeat a further 12 mgs Side Effects: flushing, shortness of breath, chest discomfort, SENCE OF IMPENDING DOOM Cautions: asthmatics, patients with heart blocks 65

66 Isoprenaline Action: Synthetic sympathomimetic related to adrenaline Purely Beta receptor stimulator, bronchodilator, positive inotrope, chronotrope and dromotrope Indications Bradyarrhythmias with pulse refractory to atropine Dose mcg bolus Complications Tachyarrhythmias Increased MVO2 66

67 Calcium Seldom indicated in management of cardiac arrest Action: Electrolyte essential for muscle activity Increases excitability/ contractility & peripheral resistance Indications: Arrhythmias associated with hyperkalaemia hypocalcaemia Overdose of calcium channel blockers Dosage: 5-10mls 10% calcium chloride 20mls 10% calcium gluconate 67