Therapeutic Hypothermia - Administration of Treatment

Administration of Treatment

Therapeutic hypothermia should be initiated as soon as possible in patients facing possible ischemic injury as time moderates hypothermia’s effectiveness as a neuroprotectant. Much of the animal data suggests that the earlier hypothermia is induced the better the subject’s outcome. However, therapeutic hypothermia remains partially effective even when initiated as long as 6 hours after collapse. Patients entering a state of induced hypothermia should be closely monitored. Clinicians must remain watchful of the adverse events associated with hypothermia. These adverse events include: arrhythmia, decreased clotting threshold, increased risk of infection, and increased risk of electrolyte imbalance. The medical data suggest that these adverse events can be mitigated only if the proper protocols are followed. Medical professionals must avoid overshooting the target temperature, as hypothermia’s adverse events increase in severity the lower a patient’s body temperature. The accepted medical standards assert that a patient’s temperature should not fall below a threshold of 32 °C (90 °F).

Prior to the induction of therapeutic hypothermia, pharmacological agents to control shivering must be administered. When body temperature drops below a certain threshold—typically around 36 °C (97 °F)—patients will begin to shiver. It appears that regardless of the technique used to induce hypothermia, patients begin to shiver when temperature drops below this threshold. The drugs most commonly employed to prevent shivering in therapeutic hypothermia are desflurane and pethidine (meperidine or Demerol).

Clinicians should rewarm patients slowly and steadily in order to avoid harmful spikes in intracranial pressure. A patient's rewarming should occur at a rate of a minimum of 0.17 °C/hr (0.31 °F/hr) in order to avoid injury, or a rewarming phase of at least 24 hours from 33–37 °C (91–99 °F). In fact, most deaths caused by therapeutic hypothermia occurred during the rewarming phase of the procedure, deaths that could have been easily avoided by slow and precise rewarming.