Case Presentation Cardiopulmonary Arrest: Therapeutic Hypothermia - PDF document

New Developments in Case Presentation Cardiopulmonary Arrest: Therapeutic Hypothermia • 3:40 (+ 6:00 minutes) – Columbus EMS Medic in Resuscitation 7 arrived at victim • Initial rhythm: VF Michael Sayre, MD • 3:42 (+ 8:00 minutes) – Shock once Emergency Medicine • In coma and LeRoy Essig, MD • Intubated & given Pulmonary/Critical Care Medicine amiodarone Case Presentation Cooling • Oct 11, 2007, 3:25 PM • Began therapeutic • Ohio State student, hypothermia E.H. left calculus class. • Warmed 24 hours later • 3:34 – Collapsed on • Visited patient in grass outside. hospital on post-arrest day 3… • Nurse walking by began aggressive chest compressions. • 3:35 – 9-1-1 called. • 3:36 – Ambulance dispatched. 1

Chain of Survival Nolan J. Resuscitation 2006; 71: 270-1 Objectives Enteral nutrition Insulin Cooling Inotropes • Describe clinical efficacy for therapeutic Defibrillator hypothermia for comatose victims of cardiac Ventilation arrest Pacing • Detail the methods for inducing therapeutic hypothermia • Review the political barriers to implementing a therapeutic hypothermia protocol IABP 2

Brain Hospital Care Matters Temperature Control • Prevention of hyperthermia � Hyperthermia common for 2-3 days • Takino M. Intensive Care Med 1991;17:419-20 � Hyperthermia associated with poor outcome • Zeiner A. Arch Intern Med 2001;161:2007-12 • Hickey RW. Crit Care Med 2003;31:531-5 • Therapeutic hypothermia Hypothermia: Saving the Brain Mechanism of action? • Cerebral perfusion • Sedation • Control of seizures • Glucose control • Temperature control 3

Hypothermia: Hypothermia: Mechanism of action? Mechanism of action? • Suppression of free radicals • Blocking pathological protease cascades • Suppression of apoptosis (48 h) • Suppression of pro-inflammatory cytokines (5 days) Polderman K. Lancet 2008;371:1955-69 Hypothermia: Mechanism of action? Scientific Evidence 4

Number Needed HACA Study to Treat Cooling Technique • External cooling (ED) • Plavix for STEMI: NNT = 23 (composite endpoint) • 32-34 o C for 24 hr PCI vs tPA for STEMI: NNT = 100 (mortality) • • Cooling tent +/- ice • Statins for ASCVD: NNT between 163 – 639 packs (mortality per yr of therapy) • Passive rewarming • Therapeutic hypothermia for comatose VF over 8 hours survivors: NNT = 6 (good neuro outcome) • Pancuronium • Bladder temperature Cooling was Slow Normothermia (n = 124) Hypothermia (n = 124) N Engl J Med 2002; 346: 557-63 5

The Hypothermia After Cardiac Arrest (HACA) Study Group P = 0.009 P = 0.02 NNT = 6 NNT = 7 60 55 55 50 41 39 40 Normothermia Percent (n= 137) 30 Hypothermia (n= 137) 20 10 0 Good Neurological Death outcome N Engl J Med 2002; 346: 557-63 Polderman K. Lancet 2008;371:1955-69 Therapeutic hypothermia Exclusions (relative) after cardiac arrest An Advisory Statement by the ALS Task • Severe systemic infection Force of the International Liaison Committee on Resuscitation (ILCOR) • Severe cardiogenic shock (SBP< 90 mmHg despite inotropes)?? · Unconscious adult patients with spontaneous circulation after out of hospital cardiac arrest � But: Skulec R. Acta Anaesthesiol Scand should be cooled to 32-34°C for 12-24 hours 2008;52:188-94 when the initial rhythm was VF • Established multiple organ failure · For any other rhythm, or cardiac arrest in hospital, such cooling may also be beneficial • Pre-existing medical coagulopathy Nolan J. Resuscitation 2003; 57:231-5 6

Speed of Cooling May Matter Early Cooling and Outcome • 49 consecutive patients cooled with invasive cooling (Alsius system) • 78% OHCA; 84% VF/VT • 28/49 (57%) good outcome = CPC 1 or 2 • Multivariate analysis: time to target temperature = OR 0.69 (0.51 – 0.98) for good outcome per hour Wolff B. Int J Cardiol 2008 7

Prehospital cooling versus emergency department cooling • VF cardiac arrest (n = 234) • 2 L cold saline prehospital vs. ED • Temperature � Before saline = 35.8 o C � On ED arrival = 34.4 o C versus 35.9 o C • Survival to discharge 48% (EMS) versus 51% (ED) Bernard S. Presented at ReSS 2008 New Orleans The Hard Part Inducing Hypothermia 8

Phases of Induction of Cooling Hypothermia • 2 liters of ice cold • Induction – get to < 34 o C rapidly saline kept in refrigerator • Maintenance phase – tight control (maximum fluctuation 0.2 – 0.5 o C) • Rewarming phase – slow 0.25 o C h -1 � Deranged cerebrovascular reactivity if > 37 o C – Lavinio A. BJA 2007;99:237-44 . Polderman KH. Crit Care Med 2009;37:1101-20 External Cooling Cooling Techniques External Internal � Ice packs, wet linen, � Cold IV saline fans � Intravascular � Cooling blankets catheters • Air, e.g. Polar Air • Intravascular balloons • Water, e.g. Blanketrol • Metal catheter � Pre-refrigerated cooling pads • Helix system � Hydrogel-coated pads � Cold water immersion Polderman KH. Crit Care Med 2009;37:1101-20 9

Water-circulating Surface Laerdal MediCool Cooling Device (Arctic Sun � ) Circulating cold water Arctic Sun vs Standard blankets Cooling blankets & ice bags • Multicenter, randomized trial with cooling blankets and ice (n=30) or the Arctic Sun (n=34) • Subjects cooled <34°C target at 4 hours = 71% (Arctic Sun) vs 50% (standard cooling group, p=0.12). • Median time to target was 54 minutes faster in the Arctic Sun group than the standard cooling group (p<0.01). • Survival rates with good neurological outcome were similar; 46% of Arctic Sun patients and 38% of standard patients had a cerebral performance category of 1 or 2 at 30 days (P=0.6). Heard K, et al., AHA Scientific Sessions 2007 10

External techniques: Endovascular cooling after cardiac arrest Overcooling is frequent 38 • Retrospective review of 32 cases N = 19 37 • Surface cooled to target of 32-34 o C Temp [°C] 36 � 20/32 (63%) < 32 o C 35 � 9/32 (28%) < 31 o C 34 � 4/32 (13%) < 30 o C 33 32 • Rebound hyperthermia (>38 o C) at 12-18 h 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 after rewarm in 7/32 (22%) Time after ROSC [hours] Sterz F. Curr Opin Crit Care 2003; 9: 205-10 Merchant RM. Crit Care Med 2006; 34: S490-4 Therapeutic Hypothermia: Endovascular Cooling Physiological effects / complications • Shivering • Vasoconstriction • Bradycardia • Infection, coagulopathy • Diuresis - hypovolemia • � K + , � Mg + , � Ca 2+ • � Insulin sensitivity • Impaired GI absorption Polderman KH. Crit Care Med 2009;37:1101-20 11

Prevent Shivering: Monitor Temperature • NMBA may be used • Continuously Monitor Temperature with Core • Eliminates thermoregulatory defense mechanisms temp probes • If used: � Esophageal • Paralytic infusion may be discontinued when temp is 34 °C (93.2 °F) � Pulmonary artery • If shivering occurs, then neuromuscular � Bladder probe blockade should be resumed • Also use a secondary temperature to monitor • No need to do Train of Four, it’s not • Frequency accurate in the hypothermic patient � Every 30 minutes during cooling and • Sedation rewarming • Typically used, with or without NMBA • Given continuously � Every hour during maintenance Prevent Shivering: Cardiovascular Effects • Mild bradycardia and increase in BP • Caution with maintenance dosing of � No treatment typically required sedatives and NMBA’s, as clearance • CO decreased by 25-40% decreases with hypothermia � Largely due to decreases in heart rate • Lower doses needed in elderly due to � Contractility typically increases blunted counter-regulatory response � Supply-demand balance for O2 usually maintained or improved • Peripheral vasoconstriction � Obtain good vascular access prior to cooling 12

EKG Changes Cardiovascular Effects • “Cold diuresis” � Due to vasoconstriction-induced shift of intravascular volume into central circulation � Can result in hypovolemia, particularly during induction phase • Significant risk for severe arrhythmias occurs at temps below 28-30°C � Arrhythmias low risk until temp drops below 30°C � A-fib, then V-fib � Myocardium less responsive to treatment of defibrillation EKG Changes EKG Changes 13

Other Issues Electrolyte Disorders • Bedsores • Changes to cellular homeostasis � Prolonged exposure to ice packs and � Related to dysfunction of electrolyte peripheral vasoconstriction increases pumps causing intracellular shifts risk � Risk greatest in induction phase • Nutrition • ↓ K + , ↓ Mg + , ↓ Ca 2+ � Enteral feeding should be decreased or • ↓ Insulin sensitivity and production stopped • Careful monitoring Rewarming Ventilatory Derangements • Rewarming phase – slow 0.25 o C h -1 • Hypothermia affects ABG analysis � Deranged cerebrovascular reactivity � ABG machines warm sample to 37°C if > 37 o C � Overestimates PaO2 and PaCO2 • Lavinio A. BJA 2007;99:237-44 . � Underestimates pH • Concerns � Vasodilation • Important to examine temperature- � Rebound electrolytes corrected values to avoid hypoxemia or significant alkalosis � Cardiac arrhythmias 14