Download therapeutic hypothermia

THERAPEUTIC HYPOTHERMIA
BY
Dr Dennis Prabhu Dayal
TEMPERATURE
Two temperatures are important in the human body—
Core temperature
Skin temperature.
Core temperature is the temperature of the brain and inner body, and
this temperature extends to about 2 cm beneath the body’s surface.
Skin temperature is the temperature at the skin’s surface.
In human beings core body temperature is 37 c* or 98.6 F
HYPOTHERMIA
Definition - a condition in which an organism's core
temperature drops below that required for normal
metabolism and body functions.
Hypothermia is Subdivided into four different degrees:
Mild (32 - 35ºC or 90 - 95ºF)
Moderate (28 - 32ºC or 82.4 - 90ºF )
Severe (20 - 28ºC or 68 - 82.4ºF)
Profound ( < 20ºC or < 68ºF)
Therapeutic Hypothermia
Therapeutic hypothermia(TH) also known as protective hypothermia
or targeted temperature management (TTM) is a medical treatment
that lowers a patient’s body temperature in order to help reduce the
risk of tissue injury from lack of blood flow and reperfusion.
RATIONAL OF USING HYPOTHERMIA AS A THERAPY
ISCHAEMIC INJURY
REPERFUSION INJURY
ISCHAEMIC INJURY
Cerebral anoxia
Cerebral activities are compromised
Depletion of glucose and ATP
Cells lose structural integrity
Mitochondrial damage
Calcium hemostasis disturbed
Release of excitatory neurotransmitter
Cellular necrosis
APOPTOSIS – programmed cell death
REPERFUSION INJURY
Reoxygenation promotes high concentrations of
radicals
Free oxygen
Inflammatory processes activated
(tumour necrosis factor,interleukins-1, cytokines),
Endothelial dysfunction,
Vasomotor dysregulation,
Edema,
Tissue-level hypoxia
Neurological damage.
despite
adequate
arterial
oxygenation
THEREPEUTIC BENEFIT OF HYPOTHERMIA
Experimental studies done on post cardiac arrest animals by
inducing hypothermia revealed encouraging results.
Hypothermia tempers the post-CA inflammatory cascade
aborts activated programmed cell death pathways (APOTOSIS)
Hypothermia causes improvement in the oxygen supply-anddemand mismatch by reducing:
Excitatory amino acids
Free Oxygen radicals
Cerebral metabolic rate of oxygen,
Cerebral blood volume
Intracranial pressure
HACA TRIAL
HACA TRIAL PUBLISHED IN NEW ENGLAND JOURNAL OF MEDICINE in FEB 2002
HACA (HYPOTHERMIA AFTER CARDIAC ARREST) trial was done on
post cardiac arrest
patient who attained ROSC (return of
spontaneous circulation) to compare mild therapeutic hypothermia vs
normothermia
AIM
The primary objective:
·
To study the favorable neurologic outcome within six months
after cardiac arrest.
Secondary objective :
To study mortality at six months
the incidence of complications
during the first seven days.
INCLUSION CRITERIA
witnessed cardiac arrest,
ventricular fibrillation or non perfusing ventricular tachycardia as
the initial cardiac rhythm
a presumed cardiac origin of the arrest,
an age of 18 to 75 years,
an estimated interval of 5 to 15 minutes from the patient’s collapse
to the first attempt at resuscitation by emergency medical
personnel,
an interval of no more than 60 minutes from collapse to restoration
of spontaneous circulation.
EXCLUSIONS CRITERIA
a tympanic-membrane temperature below 30°C on admission,
a comatose state before the cardiac arrest due to the administration
of drugs that depress the central nervous system,
pregnancy
response to verbal commands after the return of spontaneous
circulation
evidence of hypotension (mean arterial pressure, less than 60 mm
Hg) for more than 30 minutes
after the return of spontaneous circulation evidence of hypoxemia
(arterial oxygen saturation, less than 85 percent) for more than 15
minutes after the return of spontaneous circulation
a terminal illness that preceded the arrest,
factors that made participation in follow-up unlikely,
enrollment in another study,
the occurrence of cardiac arrest after the arrival of emergency
medical personnel
a known preexisting coagulopathy.
HACA TRIAL FEB 2002
The study was carried out between March 1996 and January 2001.
275 patients were enrolled, with 137 patients randomly assigned to
the hypothermia group and 138 to the normothermia group (i.e., the
group that received standard care after resuscitation).
Hypothermia group
A total of 75 of the 136 patients (55 percent) in the hypothermia group
had a favorable neurologic outcome
Normothermia group
A total of 54 of the 137 (39 percent) in the normothermia group had a
fovorable neurologic outcome.
Conclusion of HACA trial 2002
Treatment with hypothermia may be of value in terms of public health.
Each year, cardiac arrest occurs in approximately 375,000 people in
Europe, about 30,000 of whom would meet our inclusion criteria.
“We can be 95 percent confident that treatment with hypothermia would
prevent an unfavorable neurologic outcome in 1200 to 7500 of these
patients.”
(HACA TRIAL 2002)
TARGETED TEMPERATURE MANEGEMENT TRAIL IN 2013
This trial studied unconscious survivors of out-of-hospital cardiac arrest .
Therapeutic hypothermia is recommended by international guidelines, but
the supporting evidence is limited, and the target temperature associated
with the best outcome is unknown. Objective of TTM trial was to compare
two target temperatures, both intended to prevent fever.
AIM:
The primary objective for study was all-cause mortality through the end of
the trial.
Secondary objective was to study a composite of poor neurologic function or
death at 180 days.
INCLUSION CRITERIA
Out of hospital cardiac arrest
18 years+
GCS less than 8
Arrest of presumed cardiac origin
Both shockable /non shockable rthyms
20 consecutive minutes of spontaneous circulation
EXCLUSION CRITERIA
an interval from the return of spontaneous circulation to screening of
more than 240 minutes
unwitnessed arrest with asystole as the initial rhythm
suspected or known acute intracranial hemorrhage or stroke
body temperature of less than 30°C.
TTM TRIAL 2013
In total, 939 patients were included in the primary analysis.
33°C group
50% of the patients in the 33°C group (235 of 473 patients) had died,
36°C group
with 48% of the patients in the 36°C group (225 of 466 patients) had died
At the 180-day follow-up, 54% of the patients in the 33°C group had died
or had poor neurologic function as compared with 52% of patients in the
36°C group .
After analysis the comparable rate was 52% in both groups.
CONCLUSION
In conclusion, TTM trial does not provide evidence that targeting a
body temperature of 33°C confers any benefit for unconscious patients
admitted to the hospital after out-of-hospital cardiac arrest, as
compared with targeting a body
temperature of 36°C.
THERAPEUTIC MANAGEMENT AS PER AHA GUIDELINES
AHA RECOMMMENDATION
CLASS 1 FOR VF/VT RHYTHMS
CLASS 2B FOR NONSHOCKABLE RTHYMS
EUROPEAN RESUSCITATTIVE COUNCIL RECOMMENDS FOR ALL, BUT
ACKNOWLEDGES THAT BENEFIT IS LESS IN NONSHOCKABLE RTHYMS.
STAGES OF THERAPEUTIC HYPOTHERMIA
INITIATION
MAINTENANCE
REWARMING
NORMOTHERMIA
COMPLICATIONS OF THERAPEUTIC HYPOTHERMIA
Diuresis
Electrolyte imbalance
Immunosuppression
There is a 20% increase in mortality for every hour of
delay in the initiation of therapeutic hypothermia
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