What Conditions Are Treated With Targeted Temperature Management (Therapeutic Hypothermia)?

Targeted temperature management or therapeutic hypothermia is a type of treatment in which healthcare providers use cooling devices to lower the body temperature for a short time. When a person gets a cardiac arrest, the heart suddenly stops beating, and blood flow to the organs including the brain is affected. This can cause lasting damage. Lowering the body temperature to approximately 32-36°C right after a cardiac arrest can reduce the damage to the brain and improves the chances of recovery. Because during hypothermia, various metabolic processes slow down, which leads to a reduced requirement of blood by the organs.

During the procedure, the patient’s body is cooled using an induced hypothermia protocol for 24 hours to a goal temperature of 32-36°C. The goal is to achieve the target temperature as quickly as possible. In most cases, it can be achieved within three to four hours of initiating cooling. Rewarming begins 24 hours after the time of initiation of cooling when the person is brought back to their normal body temperature (around 37°C). During a therapeutic hypothermia procedure, the patient is given medications such as sedatives and painkillers beside medicines to prevent shivering.

The following body responses are associated with therapeutic hypothermia:

• Reduction in brain metabolism (approximately 6-8% per 1°C fall in body temperature) and demand for oxygen and nutrients
• Reduction of brain excitatory substances (such as reduced glutamate release)
• Preservation of brain structure and function along with stabilizing the blood-brain barrier (the barrier that allows selective passage of substances from the blood to the brain and vice versa)
• Reduced formation of the damaging free radicals and toxins
• The reduced tendency for cell damage and death
• Restoration of normal body processes such as protein synthesis and gene expression
• Inhibition of harmful inflammatory products (e.g., cytokines, interleukins and arachidonic acid cascade end products)

In the heart, hypothermia may reduce the area of injury, reduce the metabolic demand, and preserve the energy stores of the heart cells. Thus, therapeutic hypothermia reduces and retards the damaging processes that would occur if the patient is kept at their normal body temperature. It, therefore, allows the doctor to buy time until definitive therapy is provided to the patient.

The major side effects of therapeutic hypothermia are

• Shivering
• Arrhythmia (abnormal or irregular heart rhythm)
• Infections
• Blood clots
• Bleeding
• Electrolyte and metabolic disturbances
• Cold diuresis and hypovolemia (loss of fluids from the body due to increases urination caused by hypothermia)