EBQ:HACA

incomplete Journal Club Article

Holzer M, et al. "Mild Therapeutic Hypothermia to Improve the Neurologic Outcome After Cardiac Arrest". The New England Journal of Medicine. 2002. 346(8):549-556.
PubMed Full text PDF

Clinical Question

Does mild hypothermia improve neurologic outcomes compared with standard care normothermia in patients surviving ventricular fibrillation or pulseless ventricular tachycardic arrest?

Conclusion

In patients who have been successfully resuscitated after cardiac arrest due to ventricular fibrillation, therapeutic mild hypothermia increased the rate of a favorable neurologic outcome and reduced mortality

Major Points

• Therapeutic Hypothermia, define as deliberate cooling of a patient to 32-33.9°C (90-93F) who has no return of spontaneous neurologic activity after cardiac arrest. The goal is to reduce the repercussion injury to the brain which may be related to free radical formation, micro and macro circulation disruption and protease activation. At therapeutic temperatures the disruption of inflammatory and damaging cascades within the brain are thought to be decreased.

The HACA Trial (Hypothermia after Cardiac Arrest) randomized patients after witness Ventricular Fibrillation (VF) and pulseless Ventricular Tachycardia (VT) to 32-34°C Hypothermia. There was a significant patient centered outcome and 6 month mortality decrease in the hypothermia group. A later trial by Bernard et. al. demonstrated similar benefit and subsequent Cochrane reviews and the TTM Trial (33°C vs 33°C) found similar mortality and morbidity benefits.

• Standard care established by the ACCF/AHA 2013 guidelines, recommend therapeutic hypothermia for any comatose patient with a STEMI and out of hospital cardiac arrest from VF or puleless VT

Study Design

• Randomized, Multicenter, unblinded treatment with blinded final outcome assessment.
• N=275
  • Normothermia control group (n=138)
  • Hypothermia treatment group (n=137)

Population

• Emergency Department enrollment

Patient Demographics

• Age: 59 yrs
• Male: 77%
• Witnessed arrest: 99%
• VF or Pulseless VT: 97%
• Bystander CPR:
  • 49% normothermic group
  • 43% hypothermic group
• Thrombolysis after resuscitation: 19%
• Total epinephrine dosing: 3mg
• Location of cardiac arrest:
  • Home: 51%
  • Public Place: 37%
  • Other: 12%

Inclusion Criteria

• Witnessed cardiac arrest
• Ventricular fibrillation or nonperfusing ventricular tachycardia as initial cardiac rhythm
• Presumed cardiac origin of the arrest
• Age of 18 to 75 years
• Estimated interval of 5 to 15 minutes from the patient’s collapse to the first attempt at resuscitation
• No more than 60 minutes from collapse to restoration of spontaneous circulation

Exclusion Criteria

Patients were excluded if they met any of the following criteria:

• Tympanic-membrane temperature below 30°C on admission
• Comatose state before the cardiac arrest due to the administration of drugs that depress the central nervous system
• Pregnancy
• Response to verbal commands after ROSC and before randomization
• Hypotension (mean arterial pressure, less than 60 mm Hg) for more than 30 minutes after ROSC
• Hypoxemia (arterial oxygen saturation, less than 85 percent) for more than 15 minutes after ROSC
• Terminal illness that preceded the arrest
• Factors that made participation in follow-up unlikely
• Enrollment in another study
• Cardiac arrest after the arrival of emergency medical personnel
• Coagulopathy

See Also

• Therapeutic Hypothermia
• TTM Trial