Therapeutic hypothermia (TH) is a procedure endorsed by the American Heart Association. It is considered an important therapy for a survivor of cardiac arrest—someone whose heart stopped beating, was restarted during cardiopulmonary resuscitation (CPR), and remains minimally responsive immediately after the event. It is performed by lowering the body temperature to 32-34ºC (approximately 90 to 93ºF). Normal body temperature is 98.6º F or 37ºC.
How Does Hypothermia Help?
Hypothermia works by protecting the brain and other vital organs. It lowers oxygen requirements, decreases swelling, and limits the release of toxins, which can cause cells to die. It has been shown to improve neurological outcomes and increase survival in patients who remain in a coma after successful CPR.
What are the Risks to Cooling?
There are few risks associated with mild hypothermia. On the other hand, this therapy offers important benefits to survival and neurological recovery. Patients under hypothermia are monitored closely by the health care team in the McLeod Coronary Care Unit (CCU).
How is Hypothermia initiated and maintained?
To minimize neuronal injury the cooling should be initiated as quickly as possible. A new cooling method of hypothermia care is now available at McLeod that helps expedite the process. This new method provides the power and control to rapidly, safely and effectively manage the core body temperature from the inside out through the use of catheters. The catheter is inserted into the central venous system through the femoral, subclavian or internal jugular insertion sites. Cool saline is then circulated through the multiple balloons on the catheter, cooling the patient as venous blood passes over each balloon.
When Should Cooling Begin and How Long Will it Last?
Cooling should began as soon as possible after a cardiac arrest. The therapy will be continued for approximately 24 hours. The patient is then re-warmed slowly until the body temperature returns to normal (37°C).
Recovery occurs on an individual basis. Some patients wake up very quickly after the re-warming is complete. Some patients may take longer. Once a patient is removed from hypothermia, a definitive determination whether the procedure was a success cannot be made for 72 hours.