A Trial of Therapeutic Hypothermia Via Endovascular Approach in Awake Patients with Acute Ischemic Stroke: Methodology

Background: Therapeutic hypothermia has been shown to be of benefit in improving neurological outcome in cardiac arrest. It now is being investigated in acute stroke and myocardial infarction. The majority of the literature describes its use in intubated, pharmacologically paralyzed patients, using surface cooling techniques that are susceptible to patient shivering, imprecise temperature control, time lag to target-temperature acquisition, and rebound hyperthermia.

Objectives: To develop a method of inducing therapeutic hypothermia in a rapid, precise, and tolerable fashion in awake, nonintubated patients.

Methods: This method was developed for an ongoing clinical trial investigating a combination of therapeutic hypothermia and intravenous thrombolysis for acute ischemic stroke. In the protocol, an endovascular cooling device is placed in the inferior vena cava of a patient, and a combination of buspirone, meperidine, and cutaneous warming with a heating blanket is used to suppress shivering as the patient is cooled to a target temperature of 33 degrees C, kept there for a total of 24 hours from hypothermia initiation, and then rewarmed in a controlled fashion during the next 12 hours.

Results: Ten patients underwent the therapeutic hypothermia protocol. The median pretreatment core temperature was 36.1 degrees C (interquartile range [IQR]: 35.8 degrees C-36.4 degrees C). On initiation of cooling, the core temperatures dropped rapidly and then leveled off, approaching a median plateau value of 33.4 degrees C (IQR: 33.2 degrees C-33.9 degrees C) in a mean time of 1.7 (+/- 0.7) hours from cooling initiation, with a median average postplateau temperature during the cooling phase of 33.8 degrees C (IQR: 33.3 degrees C-34.6 degrees C), and a median lowest temperature of 33.1 degrees C (IQR: 33.0 degrees C-33.3 degrees C). The procedure was well tolerated, with minimal shivering and no rebound hyperthermia.

Conclusions: This is a method by which a rapid and precise therapeutic decrease in core temperature can be achieved without the necessity for intubation or neuromuscular blockade and with minimal patient discomfort or shivering.