Therapeutic hypothermia is a medical technique used after cardiac arrest, which consists of cooling the body to decrease the risk of neurological injuries and the formation of clots, increasing the chances of survival and preventing sequelae. In addition, this technique can also be used in situations such as traumatic brain injury in adults, ischemic stroke and hepatic encephalopathy.
This technique should be started as soon as possible after cardiac arrest, as the blood immediately stops transporting the necessary amount of oxygen for the brain to function, but it can be delayed up to 6 hours after the heart beats again. However, in these cases the risk of developing sequelae is greater.
How is done
This procedure consists of 3 phases:
- Induction phase: the body temperature is reduced until reaching temperatures between 32 and 36ºC; Maintenance phase: temperature, blood pressure, heart rate and respiratory rate are monitored; Reheat phase: the person's temperature rises gradually and in a controlled way, in order to reach temperatures between 36 and 37.5º.
For the cooling of the body, doctors can use various techniques, however, the most used include the use of ice packs, thermal mattresses, ice helmet or ice cream directly into the vein of patients, until the temperature reaches values between 32 and 36 ° C. In addition, the medical team also uses relaxing remedies to ensure the person's comfort and prevent the appearance of tremors
Generally, hypothermia is maintained for 24 hours and, during that time, heart rate, blood pressure and other vital signs are constantly monitored by a nurse in order to avoid serious complications. After that time, the body is slowly heated up to a temperature of 37ºC.
Why it works
The mechanism of action of this technique is not yet completely known, however, it is believed that the reduction of body temperature decreases the electrical activity of the brain, reducing the expenditure of oxygen. That way, even if the heart is not pumping the required amount of blood, the brain still has the oxygen it needs to function.
In addition, lowering body temperature also helps to prevent the development of inflammation in brain tissue, which increases the risk of damage to neurons.
Possible complications
Although it is a very safe technique, when performed in the hospital, therapeutic hypothermia also has some risks, such as:
- Changes in heart rate due to a marked decrease in heart rate; Decreased clotting, increasing the risk of bleeding; Increased risk of infection; Increased amounts of blood sugar.
Due to these complications, the technique can only be performed in an Intensive Care Unit and by a trained medical team, since it is necessary to make several assessments over the 24 hours, to decrease the chances of developing any type of complication.
