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Cardiac Arrest Management

Cardiac Arrest Management. Last Time. Vasopressors Inotropes. Today. Post cardiac arrest management Targeted Temperature Management (TTM). Case. 54yr old tax lawyer Collapses on Liverpool St Station Anaethetist on scene who finds AED ROSC afer 15min but patient remains unconscious

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Cardiac Arrest Management

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  1. Cardiac Arrest Management

  2. Last Time • Vasopressors • Inotropes

  3. Today • Post cardiac arrest management • Targeted Temperature Management (TTM)

  4. Case • 54yr old tax lawyer • Collapses on Liverpool St Station • Anaethetist on scene who finds AED • ROSC afer 15min but patient remains unconscious • Brought to ED

  5. Priorities • Prevent further cardiac arrest • Define the underlying pathology • Limit organ damage • Predict non-survivors

  6. Ideally patients should be taken to a cardiac intervention centre with 24/7 capabilities

  7. Prevent Further Cardiac Arrest • Optimise FiO2 • Target sats 94-98% to avoid hyperoxia • Decrease FiO2 as soon as possible • Protective lung ventilation via ETT • Commence sedation • Ventilate to normocapnia • Correct electrolyte abnormalities • Control glucose (e.g <10mmol/L) • Appropriate anti-arrythmic (e.gamiodarone)

  8. Case Continued • The patient has been up on ICU for one hour • His wife has arrived and would like to know what’s going to happen next?

  9. Define Underlying Pathology • Diagnose and treat underlying cause (PCI/thrombolysis) • Treat complications (e.g heart failure, hypotension, rib fractures, pneumothorax) • Cath lab on ECMO or LUCAS if refractory arrest • Assess neurology

  10. Case Continued • Patient has come back to the unit following PCI • 3 stents to a heavily narrowed LAD

  11. Cooling • Seems to get everyone hot under the collar • Although there are risks, they are largely theoretical • Instead, concerns about spending on infrastructure

  12. Theory behind cooling • Global ischaemia-reperfusion injury • Aim is to reduce: • Cerebral metabolism and oxygen demand • Apoptosis • Release of excitatory neurotransmitters • Cellular influx of Ca2+ • Inflammation • Free radical species • Intra and extra-cellular acidosis • Disruption of the blood-brain barrier etc.

  13. Adverse effects of cooling • Bradycardia and arrhythmias • Electrolyte abnormalities • Impaired platelet function and coagulopathy • Depressed immune function • Reduced insulin sensitivity • Prolonged drug effects from decreased clearance

  14. Prior to 2013, the term “therapeutic hypothermia” was used • This was replaced with Targeted Temperature Management (TTM) after concerns that hypothermia wasn’t a necessary component

  15. Experimental animal data strongly supported cooling immediately after and perhaps before intervention • NICE recommends cooling “as soon as possible after cardiac arrest” • 1359 survivors of OHCA randomised to pre-hospital cooling or standard care (which included cooling in most) • Not associated with improved survival or neurological outcome. • Any cooling should take place once in hospital

  16. Cooling – nothing new • 1940’s • Knowledge of the deleterious effects of cerebral anoxia on brain volume noted • 1950’s • Benefits of cooling on brain blood flow and volume noted • 1950’s • Suggestion that cooling may be of benefit to the brain post cardiac arrest first investigated

  17. 1959 • 27 patients with cardiac arrest • Excluded 8 as immediately perfectly healthy post-resus (did they really arrest?) • 7 – no cooling • 12 – cooled within 6 hrs of ROSC to 31-32 deg C • No cooling 1/7 survived (14%) • Cooling 6/12 survived (50%) • Survivors had no neurological deficit

  18. “Modern” Trials • We had to wait until the late 1990’s for further trails to be conducted – most published between 2000-2005 • 2 from the NEJM… • Bernard et al 2002 • HACA Study Group 2002

  19. Bernard et al • 4 hospital Australian randomised trial (Melbourne) • Included men >18 yrs and women >50 yrs (to minimise risk of cooling pregnant women) • Cardiac arrest initial rhythm VF • ROSC • Persistent coma • Excluded those with cardiogenic shock or other likely cause of coma (drugs, trauma, etc.)

  20. Bernard et al • Randomly assigned (odd days – cooled, even days not cooled) to standard management with or without cooling • Started by the paramedics • Cooling – cooling ice packs • Standard – • “Correction of CV instability” • Invasive ventilation • Midazolam & vecuronium • PaO2 100mmHg, PaCO2 40mmHg • MAP 90-100, • Thrombolytics (if required) & heparin • Lidocaine & K+ (target >4) • Insulin (glucose <10) • Aspirin to all

  21. Bernard et al • Cooled to 33 degrees • Packs removed • Kept paralysed to prevent shivering and kept at 33 until 12 hrs post-arrival at hospital • Actively rewarmed from 18 hrs post-arrival • Withdrawal of care at 72 hrs if no neurological recovery • Good outcome – normal to moderate disability

  22. Bernard et al • 43 cooled • 15 normal/minimal disability • 6 moderate disability • 0 severely disabled but awake • 0 severely disabled but unconscious • 22 dead • 48.8% good outcome • p=0.046 • 34 not cooled • 7normal/minimal disability • 2 moderate disability • 1 severely disabled but awake • 1 severely disabled but unconscious • 23 dead • 26.5% good outcome

  23. Bernard et al • no record of baseline neurological status prior to the event • no record of GCS on arrival in ED • good outcome: home or rehab facility at discharge (rather than a structured assessment) • positive outcome of trial would have been lost if 1 patient in good outcome group had a bad outcome

  24. HACA • Hypothermia After Cardiac Arrest study group • Included • 18-75yrs • <15 mins until resus started • Witnessed arrest, pulseless VT or VF • <60 mins until ROSC • Excluded • <30 deg on admission, coma before arrest, MAP <60 post arrest for >30 mins, hypoxaemia >15 mins post-arrest, terminal illness, coagulopathy

  25. HACA • Randomised, blinded outcome, controlled • Standard or standard + cooling • Standard therapy involved sedation for 32 hrs (no comment on ACS treatment) • Cooling – 32-34 deg C for 24 hrs • Passive rewarming

  26. HACA • Primary outcome – favourable neuro outcome • Pittsburg cerebral-performance category 1 or 2 • 1 – good recovery • 2 – moderate disability • 3 – severe disability • 4 – veg state • 5 – death

  27. HACA • Secondary endpoints • 6 month mortality • Complications within 7 days: • Bleeding of any severity • Pneumonia • Sepsis • Pancreatitis • Renal failure • Pulmonary oedema • Seizures • Arrhythmias • Pressure sores

  28. HACA • Standard (138 pts) • Favourable neuro outcome 54/137 (39%) • Death 76/138 (55%) • Cooled (137) • Favourable neuro outcome 75/136 (55%) • P=0.009 • Death 56/137 (41%) • P=0.02

  29. HACA

  30. HACA • no active temperature control — usual care group were not actually normothermic, they tended to be hyperthermic • trial stopped early • only 8% of screened ED patients were included

  31. Cochrane Review 2010 • “Conventional cooling methods to induce mild therapeutic hypothermia seem to improve survival and neurologic outcome after cardiac arrest” • Based on 5 papers (including the 2 we’ve just looked at)

  32. Clinical Recommendations • Resuscitation Council, ILCOR, AHA Guidelines – post-arrest care • Cool • Comatose survivors of out-of-hospital cardiac arrest caused by VF • (and pulseless VT but this is not in the guidelines) • Consider induced hypothermia for non-shockable rhythms

  33. Practice • Rapid induction of hypothermia • Stable and controlled maintenance • Controlled re-warming

  34. Methods of Cooling • Ice-cold Crystalloid at 20-40ml/kg bolus • Intra-vascular cooling catheters • Extra-corporeal circuits • Cooling blankets/pads • Cooling Helmet • Cold Air Tent • Ice packs • Few studies comparing feasibility and efficacy • No recommendations for a specific method as no study has evaluated implications on survival benefit

  35. When to Cool? • Animal studies suggest cooling during CPR or immediately after ROSC is associated with better organ preservation • Trials are coming… • Till then, aim to initiate cooling as soon as possible

  36. How long to Cool? • Recent studies maintained hypothermia for 24hrs, however, 12 hour protocols have been used • More studies are needed

  37. Re-warming • Rate of re-warming has not been studied, however, traditional recommendations are 0.3-0.50C per hour • Avoid rebound hyperthermia

  38. But… • TTM Trial • 17th November 2013 • NEJM • Targeted temperature management at 33°C versus 36°C after cardiac arrest • Nielsen et al

  39. TTM Trial • Background • We don’t know what the target temperature should be • The HACA study standard treatment arm – lots of pyrexia • Was the cooling the source of benefit or was it just the avoidance of pyrexia?

  40. Patients • >18 years old • GCS <8 on hospital admission after OOH cardiac arrest • Any presenting rhythm • Presumed cardiac cause of arrest • >20 mins of spontaneous circulation after arrest • Excluded • >2 hrs between ROSC and screening to include in trial • Unwitnessed arrest with asystole as presenting rhythm • Suspected or known CVA or IC bleed • <30°C

  41. Methods • Multicentre • Randomly assigned to 33 vs. 36°C • Treating clinicians were aware of trial arm • Investigators and those performing neurological testing and prognostication were not • 36hrs – cooled rapidly (various methods) to target temp for 24hrs • Gradual rewarming (<0.5°C/hr) to 37°C • Sedation off at 36hrs • Kept <37.5°C until 72hrs

  42. Prognostication and withdrawal • If still unconscious… • 72hrs after the end of the intervention • Neurological examination and recommendation regarding continuing care made

  43. Outcome measures • Primary • All cause mortality until 180 days after enrolment • 900 patients needed • Secondary • Poor neurological function • Mortality at 180 days • Adverse events

  44. Results • Mortality during trial period • 33°C – 50% • 36°C – 48% (p=0.51) • Neurological outcome • CPC • 33°C – 54% • 36°C – 52% (p=0.78) • Mod Rankin • 33°C – 52% • 36°C – 52% (p=0.87) • Dead at 180 days • 33°C – 48% • 36°C – 47% (p=0.92)

  45. Adverse events • More adverse events in the 33°C group (93% vs. 90% - p=0.09) • Hypokalaemia more likely in the 33°C group (19% vs. 13% - p=0.02) • Causes of death similar between the groups

  46. Conclusion • No benefit in cooling to 33°C over 36°C

  47. Issues with the trial • No comment on ACS treatments • This trial also advocated active prevention of fever until 72hrs – not done before

  48. My thoughts • Well designed, well conducted, adequately powered and well reported trial • Followed international recommendations for further research into this subject • It doesn’t tell us where the real benefit from cooling comes from • Is it simply fever prevention? • Is it through sedation and giving the brain a break? • Is it just good quality ICU care?

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