GHP September 2016

54 | ghp September 2016 Research & Development Reviving Accidental Hypothermic Victims with Extracorporeal Life Support The technique has been adapted from cardiac surgery as early as the 60’s and 70’s when patients were cooled down to core temperatures around 20°C in order to perform complex cardiac surgical repairs in a state of deep hypothermic cardiac arrest with good survival after rewarming to normothermia. Dr Beat Walpoth said that, “such operations would be impossible in normothermia because the brain has a tolerance to anoxia – not being perfused by blood – of about three minutes. However, when you cool the body to 20˚C, the brain’s tolerance is extended to around 30 minutes.” “After the first successful rewarming of a patient in cardiac arrest with accidental hypothermia by Profes- sor Ulrich Althaus, I joined the team at the University Hospital of Bern, Switzerland and we developed the method much further. This pioneering research has shown that it is possible to revive a victim in deep hypothermia with cardiac arrest by rewarming the body with ECLS (cardio-pulmonary bypass, or ECMO) and to give him a chance for a sequela-free long-term survival (published by our group in the New England Journal of Medicine in 1997). Prior to this event such patients would have been declared dead.” But could this technique be advanced to the point at which humans could lie dormant for years at a time? Suspended animation is the concept that lowering a person’s core temperature dramatically can enter them into a dormant state, waiting to be reanimated years later. It is a theme that is often revisited in science fiction and is regularly proposed as a way of dealing with the long timescales of interstellar travel, but how realistic is the possibility of cryonic suspension? Dr Walpoth continues, “It has always been the dream of many scientists and writers. At the moment I’m not convinced that it will be possible for the whole body to be ‘frozen’ (cryo-preserved). As you may know, it is possible for cells; you can freeze certain types of cells for 20 years or even longer and they will still carry all of their capacity when thawed.” “There is work in progress to try to apply this technol- ogy not only to isolated cells but to whole organs. So far, some organs have the potential to be cryo-pre- served at -196°C and thawed; you can, for instance, do that with simple organs such as heart valves, which function quite well after thawing. But from there, to go to ‘freezing’ a whole body is an enormous step. I don’t want to be overly optimistic or pessimistic but time will tell – my expectation is that these technologies will not be available in the near future.” The pioneering cardiovascular surgeon is the founder of the International Hypothermia Registry, which gathers patient data and collates peer-reviewed analysis to im- prove the treatment of accidental hypothermia victims. Dr Walpoth will be speaking at the World Extreme Medicine Conference and Expo at Dynamic Earth, Edinburgh, EH8 8AS on 19 November 2016. The Extreme Medicine Exposition brings together leading experts from around the globe to share learnings on prehospital care, expedition and wilderness medicine, sport, endurance, humanitarian and disaster medicine. Mark Hannaford, founder of conference organisers World Extreme Medicine, said, “Dr Walpoth’s great experience is relevant and poignant for a lot of doctors working in expedition and wilderness medicine, as hypothermia is a great danger to all mountaineers and polar explorers. “Improving the efficacy of the treat- ment of accidental hypothermia is hugely important to safety in these extreme environments, and Dr Walpoth is at the very forefront of that research. “World Extreme Medicine was founded around a campfire in Namibia, and we coined the phrase ‘World Extreme Medicine’ as an umbrella term for all prac- tices of medicine outside of a clinical environment, whether it is prehospital, disaster and humanitarian, endurance, sport, expedition or wilderness medicine. “Our message is that there is a great diversity of careers in medicine, and that traditional hospital envi- ronments are not the only option for a fulfilling career. To put it into a layperson’s terms, there’s never been a more exciting time to work in medicine.” For further information about the Extreme Medicine Expo, which takes place 18 – 21 November 2016, please Dr Beat Walpoth, director of cardiovascular research at the University Hospital of Geneva, Switzerland, is a leading surgeon and expert on rewarming victims of hypothermia using extracorporeal life support (ECLS). visit: extreme-medicine-conference-expo-2016-early/ University Hospital of Geneva: Professor Ulrich Althaus: University Hospital of Bern: International Hypothermia Registry: World Extreme Medicine Conference and Expo: World Extreme Medicine Conference Info: http:// treme-medicine-conference-expo-2016-early/ Glossary Cardio-pulmonary bypass: Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, main- taining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a heart–lung machine or “the pump”. Cryo-preserved: Cryopreservation is a process where cells, whole tissues, or any other substances suscep- tible to damage caused by chemical reactivity or time are preserved by cooling to sub-zero temperatures. ECLS: Extracorporeal life support (ECLS) is a variation of cardiopulmonary bypass. Whereas cardiopulmonary bypass facilitates open heart surgery for a number of hours, extracorporeal life support maintains tissue oxygenation for days to weeks in patients with life threatening respiratory or cardiac failure (or both). ECMO: Extracorporeal membrane oxygenation (ECMO) works by removing blood from the person’s body and artificially removing the carbon dioxide and oxygen- ating red blood cells. Generally, it is only used in the later treatment of a person with heart or lung failure as it is solely a life-sustaining intervention. Normothermia: A normal state of temperature. Sequela-Free: Living without a condition which is the consequence of a previous disease or injury. Web Address: