• Survival with good neurobehavioral outcome [ Time Frame: Measured at Month 12 ] [ Designated as safety issue: No ]
  

• Survival [ Time Frame: Measured at Month 12 ] [ Designated as safety issue: Yes ]
  
• Change in neurobehavioral function from pre-cardiac arrest to 12 months post-cardiac arrest [ Time Frame: Measured at Month 12 ] [ Designated as safety issue: No ]
  
• Neuropsychological scores (for participants who survive) [ Time Frame: Measured at Month 12 ] [ Designated as safety issue: No ]
  
• Neurological abnormality scores (for participants who survive) [ Time Frame: Measured at Month 12 ] [ Designated as safety issue: No ]
  

Cardiac arrest occurs when the heart suddenly stops beating and blood flow to the body is halted. It can occur while people are in the hospital because of a medical condition or while people are out of the hospital as a result of an accident or injury. Cardiac arrest is a serious event that is associated with high rates of death and long-term disability. When a person experiences cardiac arrest, the body undergoes severe stress and releases toxic compounds that can overwhelm the body's organs. For instance, these compounds can cause long-term brain injury.

Therapeutic hypothermia is a treatment method that involves a controlled lowering of the body temperature and then maintenance of this lower temperature for a period of time. The treatment may sufficiently slow the body's production of toxic compounds to prevent brain injury. Therapeutic hypothermia has been successfully used in adults who experience cardiac arrest to improve survival rates and health outcomes, and it has also been studied in newborn infants who have suffered from perinatal asphyxia, which is a loss of oxygen. The purpose of this study is to evaluate the effectiveness of therapeutic hypothermia at improving survival rates and reducing brain injury in infants and children who experience cardiac arrest while in the hospital.

Study researchers will conduct this study in collaboration with the following two pediatric clinical research networks: the Pediatric Emergency Care Applied Research Network (PECARN), funded by the Emergency Medical Services for Children (EMSC) program, and the National Institute of Child Health and Human Development (NICHD) Collaborative Pediatric Critical Care Research Network (CPCCRN).

The study will enroll infants and children who have suffered a cardiac arrest in the 6 hours before study entry while in the hospital. Participants will be randomly assigned to receive either hypothermia or normothermia. Participants receiving hypothermia will have their body temperature reduced to between 32° and 34° Celsius (C) and will remain at this temperature for 2 days. Their body temperature will then be slowly increased to the normal temperature of 36° to 37.5° C, which will be maintained until 5 days after the cardiac arrest. Participants receiving normothermia will have their normal temperature maintained between 36° and 37.5° C for 5 days after the cardiac arrest. Special temperature control blankets will be placed on participants to maintain their body temperature in the assigned range. After 5 days, each participant's temperature will be managed by their medical care team.

While participants are in the hospital, they will undergo frequent blood and urine collections, chest x-rays, and temperature measurements; parents of participants will complete questionnaires. When participants are ready to leave the hospital, study researchers will perform a physical and functional assessment. Twenty-eight days after the cardiac arrest, researchers will contact parents of participants to gather information on the participants' health and medical condition. At Months 3 and 12, a child development expert will contact parents to gather medical information. At Month 12, participants will attend a study visit for a neurologic examination and testing with a psychologist trained in rehabilitation.