Psychosis is a psychopathological syndrome that can be triggered or caused by exposure to high al... more Psychosis is a psychopathological syndrome that can be triggered or caused by exposure to high altitude (HA). Psychosis can occur alone as isolated HA psychosis or can be associated with other mental and often also somatic symptoms as a feature of delirium. Psychosis can also occur as a symptom of high altitude cerebral edema (HACE), a life-threatening condition. It is unclear how psychotic symptoms at HA should be classified into existing diagnostic categories of the most widely used classification systems of mental disorders, including the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and the International Statistical Classification of Diseases and Related Health Problems (ICD-11). We provide a diagnostic framework for classifying symptoms using the existing diagnostic categories: psychotic condition due to a general medical condition, brief psychotic disorder, delirium, and HACE. We also discuss the potential classification of isolated HA psychosis into those cate...
The pre-travel consultation is usually dominated by discussion and advice on preventing infectiou... more The pre-travel consultation is usually dominated by discussion and advice on preventing infectious diseases. Yet, they account for only a few percent of deaths during travel. It is important the Travel Medicine practitioner looks beyond infectious diseases and advises on environmental harms, including the importance of road traffic incidents.
As an outcome of combat injury and hemorrhagic shock, trauma-induced hypothermia (TIH) and the as... more As an outcome of combat injury and hemorrhagic shock, trauma-induced hypothermia (TIH) and the associated coagulopathy and acidosis result in significantly increased risk for death. In an effort to manage TIH, the Hypothermia Prevention and Management Kit™ (HPMK) was implemented in 2006 for battlefield casualties. Recent feedback from operational forces indicates that limitations exist in the HPMK to maintain thermal balance in cold environments, due to the lack of insulation. Consequently, based on lessons learned, some US Special Operations Forces are now upgrading the HPMK after short-term use (60 minutes) by adding insulation around the casualty during training in cold environments. Furthermore, new research indicates that the current HPMK, although better than no hypothermia protection, was ranked last in objective and subjective measures in volunteers when compared with commercial and user-assembled external warming enclosure systems. On the basis of these observations and research findings, the Committee on Tactical Combat Casualty Care decided to review the hypothermia prevention and management guidelines in 2018 and to update them on the basis of these facts and that no update has occurred in 14 years. Recommendations are made for minimal costs, low cube and weight solutions to create an insulated HPMK, or when the HPMK is not readily available, to create an improvised hypothermia (insulated) enclosure system.
Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there i... more Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there is no clear evidence that they are effective. We review the physics of thermal insulation by URFs and discuss their clinical applications. A conventional view is that the high reflectivity of the metallic side of the URF is responsible for thermal protection. In most circumstances, the heat radiated from a well-clothed body is minimal and the reflecting properties of a URF are relatively insignificant. The reflection of radiant heat can be impaired by condensation and freezing of the moisture on the inner surface and by a tight fit of the URF against the outermost layer of insulation. The protection by thermal insulating materials depends mostly on the ability to trap air and increases with the number of covering layers. A URF as a single layer may be useful in low wind conditions and moderate ambient temperature, but in cold and windy conditions a URF probably best serves as a waterproof outer covering. When a URF is used to protect against hypothermia in a wilderness emergency, it does not matter whether the gold or silver side is facing outward.
A 34-y-old skier triggered a wind slab avalanche and was completely buried for over 2 h. After ex... more A 34-y-old skier triggered a wind slab avalanche and was completely buried for over 2 h. After extrication by rescuers, the victim was breathing and conscious. Despite directions from the rescuers against standing up, the victim struggled to free himself and ultimately stood upright before collapsing in cardiac arrest. The rescuers performed cardiopulmonary resuscitation during transport to a nearby trailhead, where a helicopter emergency medical services crew found that the victim was in ventricular fibrillation. After further resuscitative efforts, including advanced life support, the victim was declared dead at the scene. Afterdrop and circumrescue collapse were the most likely triggers of cardiac arrest. This case highlights a need for rescuers, emergency medical services, and hospitals to be prepared to care for victims with hypothermia. To prevent circumrescue collapse, victims with hypothermia should be extricated gently, should not be allowed to stand, and should be placed flat. This may be difficult or impossible, as in this case. Hypothermic victims in cardiac arrest may require prolonged cardiopulmonary resuscitation, preferably with mechanical compressions, during transport to a hospital that has protocols for rewarming using extracorporeal life support. Resuscitation from hypothermic cardiac arrest should not be terminated before the victim has been rewarmed.
High altitude cerebral edema (HACE) is a life-threatening condition that can affect people who as... more High altitude cerebral edema (HACE) is a life-threatening condition that can affect people who ascend to altitudes above 2500 m. Altered mental status and the presence of ataxia distinguishes HACE from acute mountain sickness (AMS). We describe a patient with subtle cognitive dysfunction, likely due to HACE that had not fully resolved. When he initially presented, the patient appeared to have normal mental status and was not ataxic. The diagnosis of HACE was missed initially but was made when further history became available. Cognitive dysfunction was then diagnosed based on abnormal performance of a clock drawing test. A formal mental status examination, using a clock drawing test, may be helpful in assessing whether a patient at high altitude with apparently normal mental status and with normal gait has HACE.
Canyoning is a recreational activity that has increased in popularity in the last decade in Europ... more Canyoning is a recreational activity that has increased in popularity in the last decade in Europe and North America, resulting in up to 40% of the total search and rescue costs in some geographic locations. The International Commission for Mountain Emergency Medicine convened an expert panel to develop recommendations for on-site management and transport of patients in canyoning incidents. The goal of the current review is to provide guidance to healthcare providers and canyoning rescue professionals about best practices for rescue and medical treatment through the evaluation of the existing best evidence, focusing on the unique combination of remoteness, water exposure, limited on-site patient management options, and technically challenging terrain. Recommendations are graded on the basis of quality of supporting evidence according to the classification scheme of the American College of Chest Physicians.
International Journal of Environmental Research and Public Health, 2022
Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousa... more Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient a...
We present a case of an un-roped mountaineer who fell into a crevasse during descent from the sum... more We present a case of an un-roped mountaineer who fell into a crevasse during descent from the summit of Denali (Mount McKinley). He was wedged about 20 m deep in the crevasse for a total of 16 h; this included 4.5 h waiting for a rescue team to arrive, and an 11.5 h extrication process. His condition deteriorated and he eventually lost consciousness. Even though the rescue team collectively felt there was little or no chance of survival, they continued until the victim was extricated from the crevasse. He was almost immediately placed in a hypothermia wrap with active warming, loaded on a rescue helicopter, and transported for 1 h 40 min to a hospital in Fairbanks, Alaska. During the flight, he was placed on supplemental oxygen. He was cold to the touch; respiration was detectable, but a pulse was not, and he was responsive to verbal stimuli. Initial bladder temperature in hospital was 26.1 • C. He was released from hospital after 14 d and made a full recovery. This case highlights an important mix of preventative and resuscitative lessons regarding crevasse rescue in an isolated location. The lessons include the dangers of travelling un-roped on a crevassed glacier, the challenges of extrication from a confined space, the fact that respirations are often more easily detected than pulses, an extended transport time to medical facilities, and the necessity of trying unorthodox extrication methods. This case emphasized the need to continue extrication and treatment efforts for a cold patient even when survival with hypothermia seems impossible.
Hypothermia is a common problem encountered by search and rescue teams. Although mildly hypotherm... more Hypothermia is a common problem encountered by search and rescue teams. Although mildly hypothermic patients can be rewarmed in the field and can then self-evacuate, the Wilderness Medical Society hypothermia guidelines suggest that a moderately hypothermic patient in the wilderness requires warming in a medical facility. The hypothermia prevention and management kit, developed by the US military, consists of a chemical heat blanket (CHB) and a heat-reflective shell. We present a case in which a hypothermia wrap and the CHB from a hypothermia prevention and management kit were used successfully to rewarm a patient with apparent moderate hypothermia in the field. We are unaware of previous reports of successful field rewarming of a patient with moderate hypothermia. We believe the use of the CHB in conjunction with a hypothermia wrap made field rewarming possible. We recommend that a CHB, along with the components of a hypothermia wrap, be carried by search and rescue teams when a hy...
In 1805, W.D., a 16-y-old boy, became hypothermic after he was left alone on a grounded boat in L... more In 1805, W.D., a 16-y-old boy, became hypothermic after he was left alone on a grounded boat in Leith Harbour, near Edinburgh, Scotland. He was brought to his own house and resuscitated with warm blankets, smelling salts, and massage by Dr. George Kellie. W.D. made an uneventful recovery. We discuss the pathophysiology and treatment of accidental hypothermia, contrasting treatment in 1805 with treatment today. W.D. was hypothermic when found by passersby. Although he appeared dead, he was rewarmed with help from Dr. Kellie and his assistants over 200 y ago using simple methods. One concept that has not changed is the critical importance of attempting resuscitation, even if it seems to be futile. Don't give up!
Avalanches are major natural hazards in snow-covered mountains, threatening people and infrastruc... more Avalanches are major natural hazards in snow-covered mountains, threatening people and infrastructure. With ongoing climate change, the frequency and types of snow avalanches may change, affecting the rates of avalanche burial and survival. With a wetter and warmer snow climate, consequences of burial may become more severe. In this review, we assess the potential effects of climate change on the frequency and characteristics of avalanches. We then discuss how these changes might affect the survival rates of subjects buried by avalanches and might influence the responses of search and rescue (SAR) teams and health care providers. While climate change is inevitable, the effects on avalanches remain elusive. The frequency of human triggered avalanches may not change, because this depends largely on the number and behavior of winter recreationists. Blunt trauma and secondary injuries will likely become more frequent as terrain roughness is expected to rise and snow cover to become thin...
The lowest recorded core temperature from which a person with accidental hypothermia has survived... more The lowest recorded core temperature from which a person with accidental hypothermia has survived neurologically intact is 11.8 C in a 2-y-old boy. The lowest recorded temperature from which an adult has been resuscitated neurologically intact is 13.7 C in a 29-y-old woman. The lowest core temperature with survival from induced hypothermia has been quoted as 9 C. We discovered a case series (n¼50) from 1961 in which 5 patients with core temperatures below 11.8 C survived neurologically intact. The lowest core temperature in this group was 4.2 C. The authors also presented cardiovascular and other physiologic data at various core temperatures. The patients in the case series showed a wide variation in individual physiological responses to hypothermia. It is not known whether survival from accidental hypothermia is possible with a core temperature below 11.8 C, but this case series suggests that the lower limit for successful resuscitation may be far lower. We advise against using core temperature alone to decide whether a hypothermic patient in cardiac arrest has a chance of survival.
Psychosis is a psychopathological syndrome that can be triggered or caused by exposure to high al... more Psychosis is a psychopathological syndrome that can be triggered or caused by exposure to high altitude (HA). Psychosis can occur alone as isolated HA psychosis or can be associated with other mental and often also somatic symptoms as a feature of delirium. Psychosis can also occur as a symptom of high altitude cerebral edema (HACE), a life-threatening condition. It is unclear how psychotic symptoms at HA should be classified into existing diagnostic categories of the most widely used classification systems of mental disorders, including the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and the International Statistical Classification of Diseases and Related Health Problems (ICD-11). We provide a diagnostic framework for classifying symptoms using the existing diagnostic categories: psychotic condition due to a general medical condition, brief psychotic disorder, delirium, and HACE. We also discuss the potential classification of isolated HA psychosis into those cate...
The pre-travel consultation is usually dominated by discussion and advice on preventing infectiou... more The pre-travel consultation is usually dominated by discussion and advice on preventing infectious diseases. Yet, they account for only a few percent of deaths during travel. It is important the Travel Medicine practitioner looks beyond infectious diseases and advises on environmental harms, including the importance of road traffic incidents.
As an outcome of combat injury and hemorrhagic shock, trauma-induced hypothermia (TIH) and the as... more As an outcome of combat injury and hemorrhagic shock, trauma-induced hypothermia (TIH) and the associated coagulopathy and acidosis result in significantly increased risk for death. In an effort to manage TIH, the Hypothermia Prevention and Management Kit™ (HPMK) was implemented in 2006 for battlefield casualties. Recent feedback from operational forces indicates that limitations exist in the HPMK to maintain thermal balance in cold environments, due to the lack of insulation. Consequently, based on lessons learned, some US Special Operations Forces are now upgrading the HPMK after short-term use (60 minutes) by adding insulation around the casualty during training in cold environments. Furthermore, new research indicates that the current HPMK, although better than no hypothermia protection, was ranked last in objective and subjective measures in volunteers when compared with commercial and user-assembled external warming enclosure systems. On the basis of these observations and research findings, the Committee on Tactical Combat Casualty Care decided to review the hypothermia prevention and management guidelines in 2018 and to update them on the basis of these facts and that no update has occurred in 14 years. Recommendations are made for minimal costs, low cube and weight solutions to create an insulated HPMK, or when the HPMK is not readily available, to create an improvised hypothermia (insulated) enclosure system.
Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there i... more Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there is no clear evidence that they are effective. We review the physics of thermal insulation by URFs and discuss their clinical applications. A conventional view is that the high reflectivity of the metallic side of the URF is responsible for thermal protection. In most circumstances, the heat radiated from a well-clothed body is minimal and the reflecting properties of a URF are relatively insignificant. The reflection of radiant heat can be impaired by condensation and freezing of the moisture on the inner surface and by a tight fit of the URF against the outermost layer of insulation. The protection by thermal insulating materials depends mostly on the ability to trap air and increases with the number of covering layers. A URF as a single layer may be useful in low wind conditions and moderate ambient temperature, but in cold and windy conditions a URF probably best serves as a waterproof outer covering. When a URF is used to protect against hypothermia in a wilderness emergency, it does not matter whether the gold or silver side is facing outward.
A 34-y-old skier triggered a wind slab avalanche and was completely buried for over 2 h. After ex... more A 34-y-old skier triggered a wind slab avalanche and was completely buried for over 2 h. After extrication by rescuers, the victim was breathing and conscious. Despite directions from the rescuers against standing up, the victim struggled to free himself and ultimately stood upright before collapsing in cardiac arrest. The rescuers performed cardiopulmonary resuscitation during transport to a nearby trailhead, where a helicopter emergency medical services crew found that the victim was in ventricular fibrillation. After further resuscitative efforts, including advanced life support, the victim was declared dead at the scene. Afterdrop and circumrescue collapse were the most likely triggers of cardiac arrest. This case highlights a need for rescuers, emergency medical services, and hospitals to be prepared to care for victims with hypothermia. To prevent circumrescue collapse, victims with hypothermia should be extricated gently, should not be allowed to stand, and should be placed flat. This may be difficult or impossible, as in this case. Hypothermic victims in cardiac arrest may require prolonged cardiopulmonary resuscitation, preferably with mechanical compressions, during transport to a hospital that has protocols for rewarming using extracorporeal life support. Resuscitation from hypothermic cardiac arrest should not be terminated before the victim has been rewarmed.
High altitude cerebral edema (HACE) is a life-threatening condition that can affect people who as... more High altitude cerebral edema (HACE) is a life-threatening condition that can affect people who ascend to altitudes above 2500 m. Altered mental status and the presence of ataxia distinguishes HACE from acute mountain sickness (AMS). We describe a patient with subtle cognitive dysfunction, likely due to HACE that had not fully resolved. When he initially presented, the patient appeared to have normal mental status and was not ataxic. The diagnosis of HACE was missed initially but was made when further history became available. Cognitive dysfunction was then diagnosed based on abnormal performance of a clock drawing test. A formal mental status examination, using a clock drawing test, may be helpful in assessing whether a patient at high altitude with apparently normal mental status and with normal gait has HACE.
Canyoning is a recreational activity that has increased in popularity in the last decade in Europ... more Canyoning is a recreational activity that has increased in popularity in the last decade in Europe and North America, resulting in up to 40% of the total search and rescue costs in some geographic locations. The International Commission for Mountain Emergency Medicine convened an expert panel to develop recommendations for on-site management and transport of patients in canyoning incidents. The goal of the current review is to provide guidance to healthcare providers and canyoning rescue professionals about best practices for rescue and medical treatment through the evaluation of the existing best evidence, focusing on the unique combination of remoteness, water exposure, limited on-site patient management options, and technically challenging terrain. Recommendations are graded on the basis of quality of supporting evidence according to the classification scheme of the American College of Chest Physicians.
International Journal of Environmental Research and Public Health, 2022
Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousa... more Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient a...
We present a case of an un-roped mountaineer who fell into a crevasse during descent from the sum... more We present a case of an un-roped mountaineer who fell into a crevasse during descent from the summit of Denali (Mount McKinley). He was wedged about 20 m deep in the crevasse for a total of 16 h; this included 4.5 h waiting for a rescue team to arrive, and an 11.5 h extrication process. His condition deteriorated and he eventually lost consciousness. Even though the rescue team collectively felt there was little or no chance of survival, they continued until the victim was extricated from the crevasse. He was almost immediately placed in a hypothermia wrap with active warming, loaded on a rescue helicopter, and transported for 1 h 40 min to a hospital in Fairbanks, Alaska. During the flight, he was placed on supplemental oxygen. He was cold to the touch; respiration was detectable, but a pulse was not, and he was responsive to verbal stimuli. Initial bladder temperature in hospital was 26.1 • C. He was released from hospital after 14 d and made a full recovery. This case highlights an important mix of preventative and resuscitative lessons regarding crevasse rescue in an isolated location. The lessons include the dangers of travelling un-roped on a crevassed glacier, the challenges of extrication from a confined space, the fact that respirations are often more easily detected than pulses, an extended transport time to medical facilities, and the necessity of trying unorthodox extrication methods. This case emphasized the need to continue extrication and treatment efforts for a cold patient even when survival with hypothermia seems impossible.
Hypothermia is a common problem encountered by search and rescue teams. Although mildly hypotherm... more Hypothermia is a common problem encountered by search and rescue teams. Although mildly hypothermic patients can be rewarmed in the field and can then self-evacuate, the Wilderness Medical Society hypothermia guidelines suggest that a moderately hypothermic patient in the wilderness requires warming in a medical facility. The hypothermia prevention and management kit, developed by the US military, consists of a chemical heat blanket (CHB) and a heat-reflective shell. We present a case in which a hypothermia wrap and the CHB from a hypothermia prevention and management kit were used successfully to rewarm a patient with apparent moderate hypothermia in the field. We are unaware of previous reports of successful field rewarming of a patient with moderate hypothermia. We believe the use of the CHB in conjunction with a hypothermia wrap made field rewarming possible. We recommend that a CHB, along with the components of a hypothermia wrap, be carried by search and rescue teams when a hy...
In 1805, W.D., a 16-y-old boy, became hypothermic after he was left alone on a grounded boat in L... more In 1805, W.D., a 16-y-old boy, became hypothermic after he was left alone on a grounded boat in Leith Harbour, near Edinburgh, Scotland. He was brought to his own house and resuscitated with warm blankets, smelling salts, and massage by Dr. George Kellie. W.D. made an uneventful recovery. We discuss the pathophysiology and treatment of accidental hypothermia, contrasting treatment in 1805 with treatment today. W.D. was hypothermic when found by passersby. Although he appeared dead, he was rewarmed with help from Dr. Kellie and his assistants over 200 y ago using simple methods. One concept that has not changed is the critical importance of attempting resuscitation, even if it seems to be futile. Don't give up!
Avalanches are major natural hazards in snow-covered mountains, threatening people and infrastruc... more Avalanches are major natural hazards in snow-covered mountains, threatening people and infrastructure. With ongoing climate change, the frequency and types of snow avalanches may change, affecting the rates of avalanche burial and survival. With a wetter and warmer snow climate, consequences of burial may become more severe. In this review, we assess the potential effects of climate change on the frequency and characteristics of avalanches. We then discuss how these changes might affect the survival rates of subjects buried by avalanches and might influence the responses of search and rescue (SAR) teams and health care providers. While climate change is inevitable, the effects on avalanches remain elusive. The frequency of human triggered avalanches may not change, because this depends largely on the number and behavior of winter recreationists. Blunt trauma and secondary injuries will likely become more frequent as terrain roughness is expected to rise and snow cover to become thin...
The lowest recorded core temperature from which a person with accidental hypothermia has survived... more The lowest recorded core temperature from which a person with accidental hypothermia has survived neurologically intact is 11.8 C in a 2-y-old boy. The lowest recorded temperature from which an adult has been resuscitated neurologically intact is 13.7 C in a 29-y-old woman. The lowest core temperature with survival from induced hypothermia has been quoted as 9 C. We discovered a case series (n¼50) from 1961 in which 5 patients with core temperatures below 11.8 C survived neurologically intact. The lowest core temperature in this group was 4.2 C. The authors also presented cardiovascular and other physiologic data at various core temperatures. The patients in the case series showed a wide variation in individual physiological responses to hypothermia. It is not known whether survival from accidental hypothermia is possible with a core temperature below 11.8 C, but this case series suggests that the lower limit for successful resuscitation may be far lower. We advise against using core temperature alone to decide whether a hypothermic patient in cardiac arrest has a chance of survival.
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