A specific group of existing heart drugs could provide support and preserve the heart in situations of severe hypothermia, according to a new Norwegian study.
Accidental hypothermia, in which the body temperature drops below 35°C, can be the consequence of a fall into a river, sea or lake with freezing waters or in any case when the body is exposed to very cold environments . For example, it takes about 15 minutes to pass out in freezing water, also because the temperature continues to drop for every minute you are in the water. Once the core temperature drops to 30°C, the heart may stop beating. The body has safety mechanisms, meticulously developed to ensure balance is maintained at all times. When a person is exposed to cold temperatures, whether they are immersed in water or exposed on land, a number of reflexes are activated. Cold core temperatures have been shown to protect the brain by lowering brain cell metabolism and inhibiting the accumulation of injury-related toxins, among other mechanisms. This explains why seemingly dead, cold individuals can be successfully reanimated. However, time is always of the essence. Prolonged exposure to low ambient temperatures will eventually overwhelm the body’s compensatory mechanisms and ultimately lead to death.
The first medical response is to start resuscitation and start rewarming the patient. Under extreme conditions, the body warming process may have exceeded 12 hours, but for most people who die from hypothermia, it is likely that the time required for this phase of treatment will not be exceeded. The reason is that the heart’s function could be profoundly affected by the cold, making it unable to pump blood to the rest of the body’s organs.
Heart warming drugs
In the research center of the Department of Experimental and Clinical Pharmacology at UiT – Arctic University of Northern Norway, they found that a specific group of existing cardiac drugs provides support during the healing warming process. Previously, the UIT research team reported promising results on sildenafil (Viagra) and a perhaps lesser-known drug called vardenafil (Levitra). They have been shown to work in cold environments, down to 20°C , and could potentially be of vital importance when rewarming severely hypothermic patients.
Current guidelines for the treatment of hypothermic patients do not call for the use of medications until the core body temperature reaches 30°C. There is simply not enough research into the effect of drugs on low body temperatures. Experimental drug administration in such cases could lead to toxicity, prolonged duration of effect, or simply no effect.
The drugs that the Norwegian research group is studying, whose identity is not yet revealed since the study is still in the preliminary stages, show beneficial effects on blood cells. To put them to the test, they tested them on human blood cells and proteins at different temperatures, the lowest of which is 20°C. The results are remarkable. Not only do the drugs work in a cold environment, such as the body in hypothermia, but they also appear to work just as potently as in normal environments.
“As it is clear that there is a knowledge gap in this area, our research brings forward new insights that could ultimately save more lives. However, before this becomes a reality, we need to continue our laboratory and clinical investigations to establish a safe practice further down the road. Who knows, we might even change the guidelines in the future,” say the Norwegian researchers.
- No one is dead until warm and dead. (sciencenorway.no)