Page 93 - Critical Care Notes

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Contraindications
■ Aortic insufficiency and regurgitation
■ Aortic aneurysm and dissection
■ Recently placed (within 12 mo) prosthetic graft in thoracic aorta

Induced or Therapeutic Hypothermia
Also called targeted temperature management. To reduce the damage to brain
cells through reduction of the brain’s metabolic activity, hypothermia is intention-
ally induced by bringing the core body temperature down to 32°–34°C
(89.6°–93.2°F). It is recommended that therapeutic hypothermia be used for up
to 24 hr, although little evidence supports this time frame. Cerebral metabolism
↓ 6%–10% for every 1° decrease in body temperature. As cerebral metabolism
↓ → brain O 2 requirements↓. Goals: ↓ ICP, ↓ HR, ↓ brain’s O 2 demand to obtain good
neurological outcome. Indications for medically induced hypothermia include:
■ Ischemic cerebral or spinal injury, including stroke recovery
■ Cerebral edema and increased intracranial pressure
■ Heart surgery
■ Patients with asystole, pulseless electrical activity, or cardiac arrest result-
ing from ventricular fibrillation (VF) or ventricular tachycardia (VT); this is
most effective within 1 hr of cardiac arrest and no later than 10 hr after
return of spontaneous circulation.
The three phases in instituting induced hypothermia are induction, maintenance,
and rewarming.
Hypothermia may be accomplished by several methods:
■ Rapid infusion of ice-cold IV fluids; use 0.9% NS or LR at 30 mL/kg
■ NG lavage with ice water
■ Evaporative cooling of the external body surface
■ External cooling with ice packs (axilla, groin, around head) or special cool-
ing blankets, iced wet sheets, fans, gel pads
■ Invasive cooling catheters
The patient may be rewarmed through the use of:
■ Cardiopulmonary bypass
■ Warm IV fluid administration
■ Warm humidified O 2 administration via ventilator
■ Warm peritoneal lavage
■ Warming blankets and over-the-bed heaters
Caution should be taken with active core rewarming because VF can occur as
the patient’s temperature increases.
CV