10/27/2009 Why hypothermia? Nathan Ruch, MD FACEP How does it work? - PDF document

10/27/2009  Why hypothermia? Nathan Ruch, MD FACEP  How does it work?  Who can we help? h h l ?  What is the pre ‐ hospital experience?  Unknown ECG tracings.  74yo male with funny feeling in his chest while shopping for shoes  Prior CABG  Prior CABG  Medications are metoprolol and aspirin  Patient is a retired pharmacist  25 with suffer cardiac arrest during this talk  About 1000 Americans today  Less than half make it to the hospital h h lf k h h l 1

10/27/2009  Cardiac arrest  450,000 sudden deaths per year in the US  Greater than 90% mortality rate  <10% discharged from the hospital  No significant decline over past few decades despite g p p  Many who “survive” have poor neurologic h h l new drugs and improved access to electrical outcome defibrillation  Return of spontaneous circulation (ROSC)  Many patients go on to die during subsequent hospitalization  Neurologic impairment often remains as a lasting morbidity  First reported 50 years ago  Decreased core temp reduces metabolic demand  Abandoned due to resource requirements and b d d d d lack of proven benefit  49 year old with pain in right arm that began while spreading mulch  No past medical history  No past medical history 2

10/27/2009  Mild Hypothermia  90 ‐ 95F (32 ‐ 35C)  Moderate Hypothermia Moderate H pothermia  82 ‐ 89F (28 ‐ 32C)  Severe Hypothemia  <82 (<28C)  Nobody really knows  Reduced basal cellular energy requirements  Reduced free radical production d d f d l d  Improved cell membrane stability  Improved immune function  Decreased cytokine production  73yo woman with palpitations  Some left chest pain and dizziness 3

10/27/2009  77 patients  43 Hypoothermia  34 Normothermia  34 Normothermia  Results  49% good outcome with hypothermia  26% good outcome with normothermia  AHA – 2005 Guidelines  ILCOR – 2002 Consensus statement  Unconscious adults with ROSC after out of hospital cardiac arrest should be cooled to 32 ‐ 34C for 12 ‐ 24 hours when the initial rhythm is VF 34C for 12 24 hours when the initial rhythm is VF  Such cooling may be useful for other rhythms and in hospital cardiac arrest 4

10/27/2009 Yes 13% No 87%  Duration on non ‐ perfusing rhythm  Bystander CPR  Early defibrillation – AED’s l d f b ll  Quality of CPR  Age  Therapeutic hypothermia  One out of 5 hospital deaths is sudden cardiac arrest.  Overall survival in US is 5 8%  Overall survival in US is 5 ‐ 8%  Good neurologic outcome in 3% of out of hospital arrests. 5

10/27/2009  Surface cooling (cooling blankets/ice bags)  Endovascular catheters  Cool IV fluids C l fl d  Cardiopulmonary bypass  Cooling caps/helmets  Rectal  Esophageal  Tympanic  Oral  PA catheter  Bladder  Axilla 6

10/27/2009  Unintentional overcooling <32C  Optimal duration unknown  Coagulopathy  12 ‐ 24 hours  Ventricular arrhythmias l h h  Shivering Sh  Increased risk of infection  Active rewarming 1C/HR  Below 30C defibrillation may not be effective  Heating blanket  Warm IV fluids  May help overcome institutional inertia  May aid in directing post arrest patient to most capable hospitals capable hospitals  Pre ‐ hospital protocols mitigate hospital delays  Improves outcome  Requires minimal equipment and training  82yo woman who slipped and struck her head while reaching for a pot in the kitchen  Triage heart rate of 58  Triage heart rate of 58  Patient denies syncope or other symptoms  ECG done by tech with no order from MD 7

10/27/2009 www.wakeems.com/saem  Wake County/Raleigh, NC:  All calls receive EMD from a single, high ‐ volume  Single, 3 rd service EMS System with 65,000 calls/year center  Reliable firefighter first response  Reliable firefighter first response  Fire first response with AED and compressions  Fire first response with AED and compressions  Resident population of ~825,000 (add 100 per day)  Paramedic response with transport ambulances  Post ‐ resuscitation patients are selectively transported  Supervisory response at paramedic level to one of 2 high volume PCI centers  Baseline [Jan 2004 ‐ Apr 2005]: Traditional CPR,  ROSC after cardiac arrest not related to trauma focus on airway or hemorrhage  New CPR [Apr 2005 ‐ Apr 2006]: Continuous  New CPR [Apr 2005 Apr 2006]: Continuous  Age 16 years or greater  Age 16 years or greater compressions, delayed intubation for VF/VT  Female without obviously gravid uterus  Impedance Threshold Device (ITD) [Apr 2006 ‐ Oct  Initial temperature >34 C 2006]  Patient is intubated (no RSI)  Induced Hypothermia [Oct 2006 ‐ Oct 2007]  Patient remains comatose without purposeful response to pain 8

10/27/2009  All EMS records are maintained in an electronic  Age less than 16 database  Obvious traumatic origin of arrest  Records with any of the following characteristics  Records with any of the following characteristics  EMS witnessed arrest S d are reviewed to determine if cardiac arrest  Arrest not in EMS control occurred:  Prison facilities  EMS Patient Disposition = cardiac arrest  Out ‐ of ‐ system intercept  CPR procedure is recorded  Arrests under direction of non ‐ EMS physician  Defibrillation is recorded  Data were analyzed using logistic regression  Primary outcome was the proportion of OOH ‐ CA patients for whom resuscitation was attempted that  Covariates offered for the regression: survived to discharge in baseline vs. hypothermia g yp  Age A phases  Gender  Secondary outcomes include (by phase):  Response time for the first defibrillator  Pulse at emergency department, survival to admission,  Witnessed status neurological intact survival to discharge  Location  Additionally, results were stratified by initial rhythm Total OOH-CA N= 1198  3124 OOH ‐ CA occurred during the study period Baseline N = 372  1442 obvious deaths (no resuscitation attempted)  1682 attempted resuscitations New CPR New CPR N= 319 N= 319  484 of 1682 were excluded due to:  119 not under EMS control/not a code ITD N= 148  109 obvious traumatic origin  70 under the age of 16 Hypothermia N= 359  206 EMS witnessed  1198 met inclusion criteria 9

10/27/2009 Mean Age 65 Percent male 58% 11.6% 16 Private Residence 81% 8.2% P<0.05* 14 7.3% 12 Witnessed Status 36% 10 4.6% Bystander CPR 36% 8 6 Mean Defibrillator 5.3 – 6.1 mins 4 Response 2 0 Initially VF/VT 26% Baseline New CPR ITD Hypo * when compared with baseline NOTE: no statistically significant difference between study periods 37% 40 P <0.05 * 8 P<0.05* 35 29% 7.8% 7 30 6 22% 6.2% 25 5 Percent 20 Neuro survival survival 4 4 12% 12% 4.4% 4 4% Intact 15 3 10 2 1.9% 5 1 0 0 Baseline New CPR ITD Hypo Baseline New CPR ITD Hypo Treatment Period Treatment Period * When compared with baseline * When compared with baseline * P<0.05 * 35 * 28% 35 30 25 30 20 25 Neuro eu o 20% 20% Intact 15 17% 20 * Baseline 10 15 * Hypo 10% 5 10 0 Baseline New CPR ITD Hypo 5 Treatment Period 0 Pulse @ ED Admit D/C Neuro * When compared with baseline * P <0.05 when compared with baseline 10

10/27/2009  Confounders  Induced hypothermia is not experimental therapy  Removal of stacked defibrillations  Protocol driven pre and post resuscitation cardiac  Protocol ‐ driven pre ‐ and post ‐ resuscitation cardiac arrest care  Improvement with procedures due to repetition  Hawthorne effect  Intention ‐ to ‐ treat analysis  Part of standard therapy post arrest (IIb/Ilb)  Few complications  Not expensive  Time sensitive  Impacts outcome (NNT 8)  14 yo girl with palpitations  Takes verapamil 240mg  Similar episodes in the past S l d h 11

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