Induction of Therapeutic Hypothermia

Comatose patients resuscitated from cardiac arrest with restoration of spontaneous circulation (ROSC)

INCLUSION CRITERIA

Post–cardiac arrest

ROSC < 30 minutes from the time of EMS arrival

Time < 6 hours from ROSC

Comatose (does not follow commands)

EXCLUSION CRITERIA

Contraindications

Patients without a pulse

Patients responsive to verbal commands

Traumatic etiology of arrest

Active or intracranial bleeding

Patient has DNR, poor baseline status, or terminal illness

ROSC >30 minutes from the time of EMS arrival

Time of initiation >6 hours from ROSC

Pregnancy

Age >80 (relative)

Asystole as initial rhythm (relative)

Severe sepsis/septic shock as cause of arrest (relative)

Cryoglobulinemia (relative)

SUPPLIES

Temperature Probe

Esophageal

Bladder

Cooling Methods

Surface cooling with ice packs

Surface cooling with blankets or surface heat-exchange device and ice

Surface cooling helmet

Internal cooling methods using catheter-based technologies

Internal cooling methods using infusion of cold fluids

Warming Methods

Warm blankets

Bair Hugger

Room temperature IV fluids

General Basic Steps

Preparation

Induction

Maintenance

Supportive therapy

Withdrawal/rewarming

TECHNIQUE

Patient Preparation

Place definitive airway

Completely expose patient

Apply cooling blankets or gel pads (if available) with nothing between skin and blankets/pads

Place core temperature probe (esophageal preferred)

Hook blankets/pads to hypothermia machine, set to 36°C

Optimize analgesia and sedation (suggestions below)

Analgesia (optimize first): Fentanyl

Sedation: Propofol (preferred); alternate: Midazolam

Titrate to Richmond Agitation Sedation Scale (RASS) −3/−4 (TABLE 13.1)

Monitor vital signs and oxygen saturation and place the patient on a continuous cardiac monitor, with particular attention to arrhythmia detection and hypotension

Induction

Keep temperature between 35°C and 36°C

If initial temperature >36°C, infuse refrigerated crystalloid at 100 mL/min to maximum initial bolus 30 cc/kg

If initial temperature remains >36°C after this amount, wait 15 minutes before giving additional 250-cc boluses every 10 minutes until goal temperature is attained

If initial temperature <36°C, allow machine to warm the patient to 35°C

Use cold IV fluids or place ice packs on the axilla/groin to reach and maintain target temperature if cooling blankets/pads are unavailable

Target temperature should be reached as quickly as possible

Start antishivering protocol (TABLE 13.2)

TABLE 13.1.

RICHMOND AGITATION SEDATION SCALE (RASS)

Score	Term	Description
+4	Combative	Overtly combative, violent, immediate danger to staff
+3	Very agitated	Pulls or removes tube(s) or catheter(s); aggressive
+2	Agitated	Frequent nonpurposeful movement, fights ventilator
+1	Restless	Anxious but movements not aggressive or vigorous
0	Alert and Calm
–1	Drowsy	Not fully alert, but has sustained awakening
–2	Light sedation	Briefly awakens with eye contact to voice (<10 seconds) (eye opening/eye contact) to voice (≥10 seconds)
–3	Moderate sedation	Movement or eye opening to voice (but no eye contact)
–4	Deep sedation	No response to voice, but movement or eye opening to physical stimulation
–5	Unarousable	No response to voice or physical stimulation