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Induced Hypothermia

Induced Hypothermia. How EMS can improve the long term outcomes for resuscitated patients. Wake EMS Induced Hypothermia Team. J. Brent Myers, MD, MPH Medical Director Paul R. Hinchey, MD, MBA, EMT-P Assistant Medical Director Joseph Zalkin, EMT-P Assistant Chief Professional Development

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Induced Hypothermia

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  1. Induced Hypothermia How EMS can improve the long term outcomes for resuscitated patients

  2. Wake EMS Induced Hypothermia Team J. Brent Myers, MD, MPH Medical Director Paul R. Hinchey, MD, MBA, EMT-P Assistant Medical Director Joseph Zalkin, EMT-P Assistant Chief Professional Development Jon Olson, MBA, MHA, EMT-P District Chief Operations Ryan Lewis, EMT-P District Chief Quality Assurance Donald Garner, EMT-P District Chief Training

  3. Induced Hypothermia(IH) • What is Induced Hypothermia? • Why IH at Wake EMS? • How does it work? • When is it indicated? • How will it be applied?

  4. What is Hypothermia? Mild Hypothermia 89.6-95°F (32-35°C) Moderate hypothermia 82.4-89.5°F (28-32°C) Severe Hypothermia <82.4°F(28°C)

  5. What is Induced Hypothermia? Active cooling of the body to below normal levels

  6. So why would you intentionally induce hypothermia? ……a little history will help…..

  7. In March of 2005, nine months prior to the November 2005 release of the AHA resuscitation guidelines, Wake County EMS System implemented new CPR protocols using the latest in resuscitation techniques and available technology.

  8. The Technique • Changed CPR: • Emphasis on effective uninterrupted compression • Decreased emphasis on importance of ventilation • Slower ventilatory rates

  9. The Technology • Use of ETCO2: • As confirmation of ETT placement • Goal directed respiratory rate

  10. The Technology • EZ IO drill: • Rapid IV access if initial IV attempt fails

  11. So……. what happened?

  12. What does that have to do with hypothermia?

  13. Dramatic Improvement? • Impact on Pre-hospital ROSC1 • From 22% to 37% of all cardiac arrests • From 38% to 45% of v-fib arrests • From 40% to 53% of witnessed v-fib arrests • Impact on discharge from hospital1 • From 10% to 12% Not really what we expected…

  14. So why the disparity? • Post Resuscitation Deaths3 • Refractory dysrhythmias (10%) • Low cardiac output states (30%) • Post Resuscitation Encephalopathy (40%)

  15. Post Resuscitation Encephalopathy (PRE) is the single largest contributor to post resuscitation deaths and poor neurologic outcomes. PRE is caused by a series of events that begin immediately following reperfusion of the brain with ROSC………

  16. PRE • Initial hypoperfusion insult followed by period of hyperperfusion with ROSC3 • Cell injury8,11 • Oxygen free radical formation • Inflammatory cascade • Glutamate mediated cell death • Loss of Autoregulation3,8,11 • Patchy intracerebral vasoconstriction • Intravascular sludging and hypoperfusion • Perfusion/demand mismatch

  17. Luxuriant Hyperperfusion ROSC Unregulated blood flow leads to oxygen free radical formation and cell injury. It triggers inflammation, glutamatemediated cell death and edema. Initial restoration of blood flow results in unregulated perfusion of the brain. This period is referred to as the luxuriant hyperperfusion period and can last from 10-30 minutes. Vasoconstriction leads to supply demand mismatch which leads to hypoperfusion and cell damage which perpetuates the inflamatory response. The post resuscitation brain develops diffuse, patchy vasoconstriction and intravascular sludging. Supply Demand Mismatch Inflammatory Response Loss of Autoregulation

  18. Factors in PRE • Inflammation and Edema • Vasoconstriction and Sludging • Supply Demand Mismatch

  19. Induced hypothermia is part of a multifaceted approach to optimizing neurologic resuscitation.

  20. Optimizing Neurologic Resuscitation Mild Induced Hypothermia (IH) • Inhibits inflammatory cascade12,14,15 • IH is time sensitive8,11,14,15 • Animal studies demonstrate time dependent benefit • Decrease metabolic demand4,5,6,7 • 5-7% decrease in metabolic demand for each degree Celsius

  21. Optimizing Neurologic Resuscitation Hypertensive reperfusion12,13,14,15 • Forced perfusion despite vasoconstriction • Vasopressors to target MAP of 90-100mmHg Hemodilution12,13 • Normal saline dilution as part of hypertensive reperfusion strategy • Reduces vascular sludging • Cold saline as a rapid cooling technique

  22. There are several landmark studies on the subject

  23. Holzer completed a metaanalysis of a few of the studies The largest is the HACA study

  24. Summary of Studies Neurologic 50% vs 14% Neurologic 23% vs 7% Survival 50% vs 23% Survival 54% vs 33% Neurologic 49% vs 26% Neurologic 55% vs 39% Survival 48% vs 32% Survival 59% vs 45%

  25. Metaanalysis21 • Short-term Benefit Ratio • 1.68;95% CI 1.29-2.07 • 6 Month Benefit Ratio • 1.44 95% CI 1.11-1.76 • Number needed to treat (NNT) • 6 patients CI (4-13)

  26. Some familiar NNT The analysis of the studies and the limited side effect profile led to several organizations making recommendations on post resuscitation hypothermia Cath capable facility versus thrombolytics Aspirin therapy for MI Beta Blocker therapy for MI 25 42 15

  27. ILCOR Advisory Statement • Unconscious adult patients with ROSC after out-of-hospital VF cardiac arrest should be cooled to 32°C - 34°C for 12 - 24 hrs. • Possible benefit for other rhythms or in-hospital cardiac arrest

  28. Aha statement Post Resuscitation Treatment • Induced hypothermia • Prevention of hyperthermia • Tight glucose control • Prevent hypocapnia • Maintain elevated MAP

  29. As part of the effort to reduce the disparity between our resuscitation rates and hospital discharge rates, Wake County EMS System began looking at the use of induced hypothermia in August of 2005. First we had to look at the effects of hypothermia…..

  30. Effects of IH • Holzer &Bernard4,21 • No statistically significant difference in complication rates in normothermic and hypothermic cohorts • Potassium shifts • Intracellular shift with induction • Extracellular shift with warming • Managed with replacement and gradual rewarming • Fluid status • Cooling causes diuresis • Warming causes hypovolemia • Requires careful monitoring of urine output and fluid status

  31. Effects of IH • Respiratory Alkalosis • Temperature corrected ABG allows changes in minute ventilation to support normal PaCO2 • Hyperglycemia • HACA group and Bernard found that high blood glucose after cardiac arrest is associated with poor neurologic outcomes but did not find any improvement with tight glucose controls. 4,5

  32. Complications of IH in Other Applications • Neutropenia • Neutropenia and increased incidence of pneumonia seen in patients exposed to prolonged hypothermia (>24hrs) in other applications • Coagulopathy18,19,20 • May alter clotting cascade, platelet function • Cardiac dysrhythmias • Little risk for clinically significant dysrhythmias if temperatures are maintained >30°C17

  33. After finding limited side effects we developed a comprehensive protocol from field implementation to hospital discharge.

  34. Wake County Plan Objective is cost effective, prehospital initiation of induced hypothermia in patients with ROSC.

  35. Wake County Plan Criteria for Induced Hypothermia Return of Spontaneous Circulation Remains Comatose Confirmed Intubation

  36. Wake County Plan Criteria for Induced Hypothermia Return of Spontaneous Circulation • Palpable Pulses • Auscultatable Blood Pressure • Non-Traumatic Event

  37. Wake County Plan Criteria for Induced Hypothermia Return of Spontaneous Circulation Remains Comatose • No purposeful movements

  38. Wake County Plan Criteria for Induced Hypothermia Return of Spontaneous Circulation Remains Comatose Confirmed Intubation • Auscultated Breath Sounds • Tube Check Device • ETCO2 Reading

  39. Wake County Plan Criteria for Induced Hypothermia Return of Spontaneous Circulation Remains Comatose Confirmed Intubation

  40. Wake County Plan Protocol for Induced Hypothermia Expose the Patient

  41. Wake County Plan Protocol for Induced Hypothermia Slowly administer Versed 0.15mg/kg up to 10mg

  42. Wake County Plan Protocol for Induced Hypothermia Administer Vecuronium 0.1mg/kg to max of 10mg

  43. Wake County Plan Protocol for Induced Hypothermia Apply Ice Packs Neck Axilla Groin

  44. Wake County Plan Protocol for Induced Hypothermia Cold Saline Infusion 30ml/kg to max of 2 Liters

  45. Wake County Plan Protocol for Induced Hypothermia Administer Dopamine 10-20 mcg/kg/min Attain a MAP of 90-100

  46. Wake County Plan Pearls of Induced Hypothermia • Be mindful when exposing the patient • Do not delay transport to cool • Constantly reassess airway patency • Do not hyperventilate the patient • If loss of ROSC, discontinue cooling and treat per appropriate protocol

  47. NOTE: If the patient does not meet criteria for IH or if the patient can not be intubated with an endotracheal tube, a LMA is placed and the patient is managed by standard post-resuscitation protocols. Protocol Review • Arrest not due to hemorrhage or trauma • Age > 16 • Remains comatose with no purposeful response to pain • Patient is intubated ROSC Initial tympanic temperature criteria is used to avoid potential overshoot of the target range Post-Resuscitation Protocol Criteria for Induced Hypothermia and Initial Temp of >34C NO ETCO2 > 20mmHg is used both to confirm tube placement and as an additional measure of successful ROSC. It is unlikely that an appropriately ventilated patient with ROSC will have an ETCO2 < 20mmHg. YES Neuro exam consists of basic evaluation of pupil response and motor response to pain Intubation Protocol ET Tube Placed and ETCO2 >20mmHg NO YES Intubated Perform Neuro Exam and Document Start Hypothermia Procedure

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