This is a prospective, interventional study aiming to assess the effectiveness of the Esophageal Cooling Device (ECD) as a temperature control modality in post cardiac arrest patients. In addition, observed adverse events during ECD use, ease-of-use, nurse satisfaction and patient outcomes will be examined.

Temperature control in comatose survivors of cardiac arrest, is a critical aspect of these patients' care. In this context, mild temperature reduction for 24 hours post cardiac arrest has been shown to improve neurological outcomes.

Hypothermia is commonly induced using a combination of internal and external cooling modalities. Internal cooling modalities include intravenous administration of cold crystalloids and intravascular cooling catheters. External or body surface cooling can be achieved using cooling blankets, adhesive pads, and ice packs. Each of these methods however, has its limitations.

Administration of intravenous refrigerated crystalloid (4°C) boluses is a simple, effective and widely available method of hypothermia induction. Lack of precise temperature control and the potential for pulmonary edema however, make this modality unsuitable for the maintenance phase of hypothermia. Surface cooling methods, such as cooling blankets and ice packs, often cause shivering, skin breakdown, and in obese patients may be ineffective. Intravascular cooling catheters require the time of a physician for insertion and bear the potential risks of line infection and deep venous thrombosis. Searching for a temperature control device that overcomes the limitations, inefficiencies and inconveniences of existing modalities is therefore strongly desired.

The ideal temperature control modality should be effective, predictable and easy to use. An esophageal cooling device has recently become available which in theory may, may possess some of these attributes. To date, there have been no published studies examining this device's efficacy. In addition, no study has documented any adverse events during it's use, or evaluated it's ease-of-use at the bedside.

This is a prospective, interventional study aiming to assess the effectiveness of the Esophageal Cooling Device (ECD) as a temperature control modality in comatose survivors of cardiac arrest (the E-Chill trial). In addition, observed adverse events during ECD use, ease-of-use, nurse satisfaction and patient outcomes will be examined.

Inclusion Criteria:

• Patients admitted to the intensive care unit after resuscitation from an out-of-hospital cardiac arrest.
• Sustained return of spontaneous circulation (no chest compressions required for >20 minutes)
• Not obeying commands to verbal instruction.
• On mechanical ventilation via endotracheal tube or tracheotomy.

Exclusion Criteria:

• Known esophageal deformity (known esophageal varices, history of esophagectomy, previous swallowing disorders, achalasia, etc.) or evidence of esophageal trauma.
• Known ingestion of acidic or caustic poisons within the prior 24 hours.
• Patients with less than 40 kg of body mass.
• Patients known to be pregnant.
• Uncontrolled coagulopathy.
• Documented intracranial hemorrhage.
• Patients presenting to the intensive care unit with a temperature < 35°C.
• Time from collapse to return of spontaneous circulation > 45 minutes or unknown.
• Time from collapse to starting chest compressions > 10 minutes or unknown.
• Time from collapse to assessment for enrollment > 12 hours.
• Patients thought to have a very low chance of surviving the next 48 hours as assessed by the research team.