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Luks, Andrew M., Thomas G. DeLoughery, Jeffrey H. Gertsch, and Suzy Stokes. Clinical conundrum: return to high altitude after cerebral venous sinus thrombosis. High Alt Med Biol. 00:00-00, 2024.
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For often unclear reasons, the survival times of critically buried avalanche victims vary widely from minutes to hours. Individuals can survive and sustain organ function if they can breathe under the snow and maintain sufficient delivery of oxygen and efflux of carbon dioxide. We review the physiological responses of humans to critical avalanche burial, a model which shares similarities and differences with apnoea and accidental hypothermia. Within a few minutes of burial, an avalanche victim is exposed to hypoxaemia and hypercapnia, which have important effects on the respiratory and cardiovascular systems and pose a major threat to the central nervous system. As burial time increases, an avalanche victim also develops hypothermia. Despite progressively reduced metabolism, reduced oxygen and increased carbon dioxide tensions may exacerbate the pathophysiological consequences of hypothermia. Hypercapnia seems to be the main cause of cardiovascular instability, which, in turn, is the major reason for reduced cerebral oxygenation despite reductions in cerebral metabolic activity caused by hypothermia. 'Triple H syndrome' refers to the interaction of hypoxia, hypercapnia and hypothermia in a buried avalanche victim. Future studies should investigate how the respiratory gases entrapped in the porous snow structure influence the physiological responses of buried individuals and how haemoconcentration, blood viscosity and cell deformability affect blood flow and oxygen delivery. Attention should also be devoted to identifying strategies to prolong avalanche survival by either mitigating hypoxia and hypercapnia or reducing core temperature so that neuroprotection occurs before the onset of cerebral hypoxia.
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Luks AM, Grissom CK. Evaluation and Management of the Individual with Recurrent HAPE. High Alt Med Biol. 00:000-000, 2024. Individuals with a history of acute altitude illness often seek recommendations from medical providers on how to prevent such problems on future ascents to high elevation. Although many of these cases can be managed with pharmacologic prophylaxis and counseling about the appropriate rate of ascent alone, there are some situations in which further diagnostic evaluation may also be warranted. One such situation is the individual with recurrent episodes of high altitude pulmonary edema (HAPE), as one of several predisposing factors may be present that warrants additional interventions beyond pharmacologic prophylaxis and slow ascent and may even preclude future travel to high altitude. This review considers this situation in greater detail. Structured around the case of an otherwise healthy 27-year-old individual with recurrent episodes of HAPE who would like to climb Denali (6,190 m), the review examines the known risk factors for disease and then provides guidance regarding when and how to evaluate such individuals and appropriate steps to prevent HAPE on further ascents to high elevation. Except in rare circumstances, a history of recurrent HAPE does not preclude further ascent to high elevation, as a multipronged approach including pharmacologic prophylaxis, careful planning about the rate of ascent, and the degree of physical effort and other strategies, such as preacclimatization, staged ascent, and use of hypoxic tents, can be employed to reduce the risk of recurrence with future travel.
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To provide guidance to clinicians about best practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention, diagnosis, and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches for managing each form of acute altitude illness that incorporate these recommendations as well as recommendations on how to approach high altitude travel following COVID-19 infection. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine in 2010 and the subsequently updated WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2014 and 2019.
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Mal de Altura , COVID-19 , Humanos , Mal de Altura/diagnóstico , Mal de Altura/prevención & control , Altitud , COVID-19/diagnóstico , COVID-19/prevención & control , Consenso , Sociedades Médicas , Prueba de COVID-19RESUMEN
With ascent to high altitude, barometric pressure declines, leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. This leads, in turn, to a series of changes over varying time frames across multiple organ systems that serve to maintain tissue oxygen delivery at levels sufficient to prevent acute altitude illness and preserve cognitive and locomotor function. This review focuses primarily on the physiological adjustments and acclimatization processes that occur in the lungs of healthy individuals, including alterations in control of breathing, ventilation, gas exchange, lung mechanics and dynamics, and pulmonary vascular physiology. Because other organ systems, including the cardiovascular, hematologic and renal systems, contribute to acclimatization, the responses seen in these systems, as well as changes in common activities such as sleep and exercise, are also addressed. While the pattern of the responses highlighted in this review are similar across individuals, the magnitude of such responses often demonstrates significant interindividual variability which accounts for subsequent differences in tolerance of the low oxygen conditions in this environment.
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Mal de Altura , Altitud , Humanos , Pulmón , Mal de Altura/prevención & control , Fenómenos Fisiológicos Cardiovasculares , Oxígeno , HipoxiaRESUMEN
Introduction: Documentation of the cause of death is important for local and national epidemiology as well as for research and public health funding allocation. Despite this, many physicians lack the skills necessary to accurately complete a death certificate. Methods: We created a 45-minute virtual workshop to improve skills in completing death certificates. Participants examined the role of death certificates in disease epidemiology and resource allocation for research and public health interventions, reviewed the components of a death certificate, and practiced correcting and filling out death certificates from actual patient cases. To assess the workshop, participants completed sample death certificates immediately before and after the workshop for two representative cases. Results: Thirty-six internal medicine residents (17 PGY 1s, 12 PGY 2s, and seven PGY 3s) completed the workshop. Prior to the workshop, 89% of the sample death certificates contained one or more errors, compared with 46% postworkshop. Major errors, such as incorrect categorization of a cause of death, decreased from 58% preworkshop to 17% postworkshop. Learners expressed discomfort after realizing they had made errors in completing previous death certificates and noted a desire for continuing education and reference materials on this topic. Discussion: Death certification is a key competency for physicians. Our virtual workshop improved participants' skills in completing death certificates. Although a significant number of errors remained after the workshop, most of these residual errors were minor and would not affect cause-of-death reporting. The durability of these improvements over time requires further study.
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Certificado de Defunción , Médicos , Humanos , DocumentaciónRESUMEN
Extracorporeal membrane oxygenation (ECMO) has emerged in the COVID-19 pandemic as a potentially beneficial yet scare resource for treating critically ill patients, with variable allocation across the United States. The existing literature has not addressed barriers patients may face in access to ECMO as a result of healthcare inequity. We present a novel patient-centered framework of ECMO access, providing evidence for potential bias and opportunities to mitigate this bias at every stage between a marginalized patient's initial presentation to treatment with ECMO. While equitable access to ECMO support is a global challenge, this piece focuses primarily on patients in the United States with severe COVID-19-associated ARDS to draw from current literature on VV-ECMO for ARDS and does not address issues that affect ECMO access on a more international scale.
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COVID-19 , Oxigenación por Membrana Extracorpórea , Síndrome de Dificultad Respiratoria , Humanos , Pandemias , Síndrome de Dificultad Respiratoria/terapiaRESUMEN
Berendsen, Remco R., Peter Bärtsch, Buddha Basnyat, Marc Moritz Berger, Peter Hackett, Andrew M. Luks, Jean-Paul Richalet, Ken Zafren, Bengt Kayser, and the STAK Plenary Group. Strengthening altitude knowledge: a Delphi study to define minimum knowledge of altitude illness for laypersons traveling to high altitude. High Alt Med Biol. 23:330-337, 2022. Introduction: A lack of knowledge among laypersons about the hazards of high-altitude exposure contributes to morbidity and mortality from acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE) among high-altitude travelers. There are guidelines regarding the recognition, prevention, and treatment of acute-altitude illness for experts, but essential knowledge for laypersons traveling to high altitudes has not been defined. We sought expert consensus on the essential knowledge required for people planning to travel to high altitudes. Methods: The Delphi method was used. The panel consisted of two moderators, a core expert group and a plenary expert group. The moderators made a preliminary list of statements defining the desired minimum knowledge for laypersons traveling to high altitudes, based on the relevant literature. These preliminary statements were then reviewed, supplemented, and modified by a core expert group. A list of 33 statements was then presented to a plenary group of experts in successive rounds. Results: It took three rounds to reach a consensus. Of the 10 core experts invited, 7 completed all the rounds. Of the 76 plenary experts, 41 (54%) participated in Round 1, and of these 41 a total of 32 (78%) experts completed all three rounds. The final list contained 28 statements in 5 categories (altitude physiology, sleeping at altitude, AMS, HACE, and HAPE). This list represents an expert consensus on the desired minimum knowledge for laypersons planning high-altitude travel. Conclusion: Using the Delphi method, the STrengthening Altitude Knowledge initiative yielded a set of 28 statements representing essential learning objectives for laypersons who plan to travel to high altitudes. This list could be used to develop educational interventions.
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Mal de Altura , Edema Encefálico , Humanos , Mal de Altura/prevención & control , Altitud , Técnica Delphi , Enfermedad AgudaAsunto(s)
Certificación , Certificado de Defunción , Educación Médica Continua , Escolaridad , HumanosAsunto(s)
Mal de Altura , Hipoxia/etiología , Viaje , Acetazolamida/uso terapéutico , Altitud , Mal de Altura/tratamiento farmacológico , Mal de Altura/etiología , Mal de Altura/prevención & control , Mal de Altura/terapia , Edema Encefálico/etiología , Edema Encefálico/terapia , Enfermedad Crónica/epidemiología , Dexametasona/uso terapéutico , Femenino , Humanos , Hipertensión Pulmonar/terapia , Hipoxia/fisiopatología , Masculino , Saturación de Oxígeno , Embarazo , Factores de RiesgoRESUMEN
Luks, Andrew M. and Colin K. Grissom. Return to high altitude after recovery from coronavirus disease 2019. High Alt Med Biol. 22: 119-127, 2021.-With the increasing availability of coronavirus disease 2019 (COVID-19) vaccines and the eventual decline in the burden of the disease, it is anticipated that all forms of tourism, including travel to high altitude, will rebound in the near future. Given the physiologic challenges posed by hypobaric hypoxia at high altitude, it is useful to consider whether high-altitude travel will pose risks to those previously infected with severe acute respiratory syndrome coronavirus 2, particularly those with persistent symptoms after resolution of their infection. Although no studies have specifically examined this question as of yet, available data on the cardiopulmonary sequelae of COVID-19 provide some sense of the problems people may face at high altitude and who warrants evaluation before such endeavors. On average, most individuals who have recovered from COVID-19 have normal or near normal gas exchange, pulmonary function testing, cardiovascular function, and exercise capacity, although a subset of individuals have persistent functional deficits in some or all of these domains when examined up to 5 months after infection. Evaluation is warranted before planned high-altitude travel in individuals with persistent symptoms at least 2 weeks after a positive test or hospital discharge as well as in those who required care in an intensive care unit or suffered from myocarditis or arterial or venous thromboembolism. Depending on the results of this testing, planned high-altitude travel may need to be modified or even deferred pending resolution of the identified abnormalities. As more people travel to high altitude after the pandemic and further studies are conducted, additional data should become available to provide further guidance on these issues.
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Mal de Altura , COVID-19 , Altitud , Humanos , Hipoxia/etiología , SARS-CoV-2RESUMEN
CASE PRESENTATION: A 79-year-old man with medical history of atrial fibrillation and esophageal cancer status post trans-hiatal esophageal resection and chemotherapy presented with altered mental status after outpatient esophagogastroduodenoscopy (EGD). One month before presentation, the patient was seen at another hospital with severe anemia and melena requiring transfusion of multiple units of RBCs. No endoscopy was performed during that admission, but his anticoagulation was held. After follow-up with his oncologist, he was referred for outpatient endoscopy. His esophagogastroduodenoscopy demonstrated an intact esophagogastric anastomosis as well as two gastric ulcers with no stigmata of recent bleeding. The patient was discharged to home in good condition with normal mental status. Several hours later, he developed a deteriorating level of consciousness, prompting presentation to the hospital.