Noncardiogenic pulmonary edema associated with accidental hypothermia

Hypothermia: Beyond the Narrative Review-The Point of View of Emergency Physicians and Medico-Legal Considerations

Hypothermia is a widespread condition all over the world, with a high risk of mortality in pre-hospital and in-hospital settings when it is not promptly and adequately treated. In this review, we aim to describe the main specificities of the diagnosis and treatment of hypothermia through consideration of the physiological changes that occur in hypothermic patients. Hypothermia can occur due to unfavorable environmental conditions as well as internal causes, such as pathological states that result in reduced heat production, increased heat loss or ineffectiveness of the thermal regulation system. The consequences of hypothermia affect several systems in the body-the cardiovascular system, the central and peripheral nervous systems, the respiratory system, the endocrine system and the gastrointestinal system-but also kidney function, electrolyte balance and coagulation. Once hypothermia is recognized, prompt treatment, focused on restoring body temperature and supporting vital functions, is fundamental in order to avert preventable death. It is important to also denote the fact that CPR has specificities related to the unique profile of hypothermic patients.

Is prehospital use of active external warming dangerous for patients with accidental hypothermia: a systematic review

BACKGROUND

Optimal prehospital management and treatment of patients with accidental hypothermia is a matter of frequent debate, with controversies usually revolving around the subject of rewarming. The rule of thumb in primary emergency care and first aid for patients with accidental hypothermia has traditionally been to be refrain from prehospital active rewarming and to focus on preventing further heat loss. The potential danger of active external rewarming in a prehospital setting has previously been generally accepted among the emergency medicine community based on a fear of potential complications, such as "afterdrop", "rewarming syndrome", and "circum-rescue collapse". This has led to a reluctancy from health care providers to provide patients with active external rewarming outside the hospital. Different theories and hypotheses exist for these physiological phenomena, but the scientific evidence is limited. The research question is whether the prehospital use of active external rewarming is dangerous for patients with accidental hypothermia. This systematic review intends to describe the acute unfavourable adverse effects of active external rewarming on patients with accidental hypothermia.

METHODS

A literature search of the Cochrane Library, MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL], and SveMed+ was carried out, and all articles were screened for eligibility. All article formats were included.

RESULTS

Two thousand three hundred two articles were screened, and eight articles met our search criteria. Three articles were case reports or case series, one was a prospective study, two were retrospective studies, one article was a literature review, and one article was a war report from the Napoleonic Wars.

CONCLUSIONS

One of the main findings in this article was the poor scientific quality and the low number of articles meeting our inclusion criteria. When conducting this review, we found no scientific evidence of acceptable quality to prove that the use of active external rewarming is dangerous for patients with accidental hypothermia in a prehospital setting. We found several articles claiming that active external rewarming is dangerous, but most of them do not cite references or provide evidence.

A case report of severe hypothermia complicated by acute respiratory distress syndrome

Acute respiratory distress syndrome has not been a described complication of hypothermia. Causes of hypothermia are commonly associated with alcohol abuse and infection, both of which could lead to acute respiratory distress syndrome. We present a case of severe hypothermia complicated by acute respiratory distress syndrome in a young immunocompetent male treated successfully with mechanical intubation and venovenous extracorpeal membrane oxygenation. Risk factors for known causes of acute respiratory distress syndrome included a witnessed aspiration event and RSV pneumonia. On review of the literature, severe hypothermia has been found to cause pulmonary edema in post-mortem studies, but acute respiratory distress syndrome has not yet been recognized as a known complication. Our case highlights that acute respiratory distress syndrome may be multifactorial in etiology and related to complications of severe hypothermia.

Pulmonary edema during the Boston Marathon

The Boston Marathon is the most popular marathon in the New England region and attracts some of the most qualified athletes participating from the United States and abroad. The race occurs in April, a month in the northeast characterized by unpredictable weather. While there are a number of well described weather-related medical complications that occur during exercise, less is known about noncardiogenic pulmonary edema (NCPE) in marathon runners, a condition that most physician are unfamiliar with. This phenomenon has been described in the literature as a complication of severe hyponatremia and cerebral edema. Here, we describe the case of a healthy athlete who took part in the Boston Marathon in 2018 and presented afterwards with hypothermia and NCPE. We also review the normal cardiopulmonary physiology along with the physiological changes and external factors impacting the respiratory system during exercise. The combination of significant physical exertion, cold and rainy weather and subsequent hypothermia, perhaps along with other less understood factors may have increased the permeability of his lungs and caused NCPE.

Pulmonary edema associated with scuba diving : case reports and review

Acute pulmonary edema has been associated with cold-water immersion in swimmers and divers. We report on eight divers using a self-contained underwater breathing apparatus (scuba) who developed acute pulmonary edema manifested by dyspnea, hypoxemia, and characteristic chest radiographic findings. All cases occurred in cold water. All scuba divers were treated with complete resolution, and three have returned to diving without further episodes. Mechanisms that would contribute to a raised capillary transmural pressure or to a reduced blood-gas barrier function or integrity are discussed. Pulmonary edema in scuba divers is multifactorial, and constitutional factors may play a role. Physicians should be aware of this potential, likely underreported, problem in scuba divers.