wilderness medicine

Drowning: Rescue, Resuscitation, and Prevention

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Drowning deaths have increased in recent years, making it more important than ever for emergency physicians manage effectively. In this episode, Corey Williams, MD, reviews current drowning terminology, the pathophysiology that drives treatment decisions, and practical pearls for resuscitation, observation, and disposition. We also discuss common misconceptions and key prevention strategies to share with patients and families (and your own!).

Guest: Corey Williams, MD; Host: Kim Bambach, MD; Audio editor: Nick Roesel

🔑 Key Learning Points:

  1. Use the modern drowning terminology:
    • Fatal or non-fatal drowning (with or without morbidity). Avoid outdated terms such as near drowning, dry drowning, and secondary drowning.
  2. Demographics:
    • Young children, adolescent males, and patients with alcohol use, seizure disorders, or developmental disabilities are at highest risk for drowning.
  3. Pathophysiology:
    • Drowning is primarily a hypoxic injury. In cardiac arrest, provide ventilations in addition to chest compressions. Compression-only CPR is not sufficient.
  4. Hypothermia:
    • Consider hypothermia when a patient has a drowning event, even in warmer months. Active rewarming remains a critical part of management.
  5. Trauma:
    • Consider cervical spine injury only when the mechanism or examination raises concern (e.g., diving injuries, unwitnessed events, neurologic deficits).
  6. Mythbusting:
    • Fresh water versus salt water does not change management. Clinically significant electrolyte abnormalities from aspiration are unlikely.
    • A normal initial chest X-ray does not rule out delayed pulmonary injury. Patients with non-fatal drowning who remain asymptomatic should generally be observed for at least 4 hours before discharge.
    • Routine prophylactic antibiotics and steroids are not recommended after drowning unless there is concern for heavily contaminated water exposure.
  7. Prevention matters:
    • Early swim lessons, four-sided pool fencing, close supervision, and CPR training for caregivers remain the most effective ways to reduce drowning-related morbidity and mortality.

📚 Further Reading:

  1. Davis CA, Schmidt AC, Bierens JJLM, et al. Wilderness Medical Society clinical practice guidelines for the treatment and prevention of drowning: 2024 update. Wilderness Environ Med. 2024;35(1):101-120. doi:10.1016/j.wem.2023.12.004.
  2. Dezfulian C, McCallin TE, Bierens J, Dunne CL, Idris AH, Kiragu A, Mahgoub M, Shenoi RP, Szpilman D, Terry M, Tijssen JA, Tobin JM, Topjian AA; on behalf of the American Heart Association and the American Academy of Pediatrics. 2024 American Heart Association and American Academy of Pediatrics focused update on special circumstances: resuscitation following drowning: an update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2024;150(23):e473-e501. doi:10.1161/CIR.0000000000001274.
  3. Szpilman D, Bierens JJLM, Handley AJ, Orlowski JP. Drowning. N Engl J Med. 2012;366(22):2102-2110. doi:10.1056/NEJMra1013317.
  4. American Academy of Pediatrics. Prevention of drowning. Pediatrics. 2021.

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Thin Air, High Stakes: Altitude Medicine

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Dr. Jonathan Thompson dives into the fascinating world of high-altitude medicine, explaining how hypoxia affects the body and lead to conditions like acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE). He highlights how hypoxia is a universal concept relevant to emergency and critical care medicine, and that understanding altitude illness can improve care for patients, whether you practice on a mountain or not!

Bio: Dr. Jonathan Thompson is a former Green Beret in the U.S. Army Special Forces and former U.S. Army Special Operations Mountaineering Instructor that taught in Colorado, Alaska, and Wyoming. He completed a Masters in Physiology at the University of Michigan with a thesis on nitrate supplementation in the prevention and treatment of acute high-altitude illnesses. He is an annual, returning guest lecturer (2020-present) at the University of Michigan’s Department of Physiology instructing undergraduate and graduate students on high-altitude physiology, pathophysiology of acute altitude illnesses, and relevant treatments.

Guest: Jonathan Thompson, MD, MS; Host: Kim Bambach, MD; Audio editor: Nick Roesel

Key Learning Points:

  1. The unifying concept: hypoxia
    • Decreased oxygen delivery impairs cellular metabolism and underlies all altitude illness.
  2. Risk of altitude illnesses begins around 5,000 feet
    • Risk increases with rapid ascent and poor acclimatization. The classic setup is flying in and ascending quickly.
  3. Physiologic response to altitude
    • Hypoxia triggers the hypoxic ventilatory response → ↑ respiratory rate and tidal volume
    • ↑ sympathetic activity → ↑ heart rate and blood pressure
    • Respiratory alkalosis from hyperventilation → renal compensation → bicarbonate excretion → diuresis
    • Over weeks, erythropoietin → ↑ red blood cell mass
  4. Altitude Illness Spectrum
    • Acute Mountain Sickness (AMS): Symptoms include headache, nausea, fatigue, and insomnia. This is usually mild but a warning sign.
    • High Altitude Cerebral Edema (HACE): Characterized by neurologic dysfunction, such as ataxia and altered mental status. HACE can be life-threatening.
    • High Altitude Pulmonary Edema (HAPE): A form of non-cardiogenic pulmonary edema. Symptoms include dyspnea at rest, cough, pink frothy sputum. HAPE is the leading cause of death.
  5. Treatment
    • Descent is the definitive treatment. Give oxygen if available (but it’s usually not in austere environments).
    • Give Acetazolamide for AMS and HACE (both prevention and treatment)
    • Give Dexamethasone for HACE (remember “HACE is AMS on steroids!”).
    • Give Nifedipine for HAPE.

The Bottom Line:

The best treatment is descent, and everything else is a bridge. When you’re out adventuring, don’t forget to go slow to acclimatize!

Check out Dr. Thompson’s lecture for the World Extreme Medicine Organization here!

Other Resources:

  1. Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update
  2. Auerbach PS, Cushing TA, Harris NS, eds. Auerbach’s Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2016.

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Sub Zero: Managing Hypothermia

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Hypothermia can be deadly and as the weather turns colder, we need to be ready to treat it. In this episode, Dr. Close (PGY-3 Chief Resident) and Dr. Kaide (Professor of EM) teach us how to manage the spectrum of hypothermia from mild cases to cardiac arrest.

Guest: Colin Kaide, MD. Host: Alex Close, MD. Editor: Kim Bambach, MD.

Key Take-Aways:

  1. Hypothermia= core body temp <95* F (35* C)
  2. Risk factors: environmental exposure (winter sports, lack of shelter), ethanol use, extremes of age, underlying illness with impaired thermoregulation (ex. sepsis)
  3. Hypothermia can progress to altered mental status/CNS depression and cardiac arrest due to arrhythmia 
  4. Have a high index of suspicion for trauma, concomitant injuries (ex: SDH after fall and prolonged time down, C spine injury in the submerged patient) 
  5. Loss of shivering is an ominous sign of moderate-severe hypothermia.
  6. For mild hypothermia rewarming may be passive external: warm environment, blankets. Remove any wet clothing. For moderate hypothermia: initiate active external measures like warm blankets/Bair hugger, warm IVF, heated humidified oxygen, targeted temperature management (ex. Zoll catheter). For the critically ill patient with severe hypothermia such as a post arrest patient: chest tube placement for thoracic lavage, consider ECMO. In a lower resource setting consider hemodialysis.
  7. In cardiac arrest the key to obtaining ROSC is high quality CPR and rewarming. Anti-arrhythmic medications have limited efficacy. Common arrhythmias are sinus bradycardia, atrial fibrillation with slow ventricular rate, VF, VT, systole. Look for Osbourne waves on EKG: a positive deflection at the J point in precordial and true limb leads. 
  8. While it is true that hypothermia can slow metabolism CPR should not be terminated until the patient has a core temp of 90*F (>32 *C) “warm and dead”, there are some exceptions such as hyperkalemia >10-12 mmol/L, arrest occurred prior to insult, obvious signs of irreversible death/major trauma, patient is rigid to the extent compressions are not possible.
  9. Always make sure you have a documented core temperature for a patient who is altered or bradycardic- it just might be due to hypothermia! 
  10. Editors note: It is also critical to obtain a finger stick glucose STAT- hypoglycemia and hypothermia frequently co-occur! 

References:

  1. Brown DA. Hypothermia. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw-Hill Education; 2020. Accessed September 12, 2024. https://accessemergencymedicine-mhmedical-com.proxy.lib.ohio-state.edu/content.aspx?bookid=2353&sectionid=220746470
  2. Kuhl E, Yamane D. . Accidental Hypothermia and Cardiac Arrest: Physiology, Protocol Deviations, and ECMO. ALiEM. December 12, 2018. Accessed September 12, 2024. https://www.aliem.com/accidental-hypothermia-cardiac-arrest-physiology-protocol-deviations-ecmo/
  3. Furgurson M. EM@3AM: Hypothermia. emDOCs.net – Emergency Medicine Education. December 19, 2020. Accessed September 12, 2024. https://www.emdocs.net/em3am-hypothermia-2/
  4. Hypothermia. Core EM. Accessed September 12, 2024. https://coreem.net/core/hypothermia/
  5. Hypothermia. EMCrit Project. Accessed September 12, 2024. https://emcrit.org/ibcc/hypothermia/

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Should You Risk It?

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What does risk mean to you and how do you approach risky clinical scenarios? As EM docs, we encounter risk every day. In this episode, Dr. Scott Stuckey gives us a new perspective by breaking down several frameworks and vocabulary we can use to think about and mitigate risk.

Residents: Dr. Stuckey completed this podcast as part of his Kiehl Professional Development Grant. You can submit a Kiehl grant to support your professional passion too!

Guest: Scott Stuckey, MD. Host: Kim Bambach, MD. Editors: Kim Bambach, MD and Creagh Boulger, MD.

Key Take-Aways:

  1. Volken’s Hazard Evaluator: Developed by Martin Volken, a professional mountain climber. Assign likelihood and the consequences. Risk = likelihood x consequence.
  2. What is your lateral emotional driver? Emotion plays a role in how we make decisions and it’s important to be aware of this. In medicine, we try to make objective assessments. Lateral emotional drivers are not necessarily negative- they can be critically important in goals of care discussions, for example.
  3. Graham’s Risk-Frequency Matrix: when you find yourself in a stressful situation, ask yourself which quadrant you’re in. That can help you understand where to put your attention to mitigate risk. High risk or low risk? High frequency or low frequency? For example, tooth splinting is low frequency low risk. Lac repairs are high frequency low risk. Intubation is high frequency high risk. Cricothyrotomy is low frequency high risk.
  4. The GAR (Green-Amber-Red) Risk Assessment: components of the situation are assigned a color related to the level of risk (green=least risk, amber= moderate risk, red=high risk). If you’re in red, how can you move into amber? If you’re in amber, how can you move into green? This often comes down to good communication with your team.
  5. The risky choice may still be the right choice for the patient.

References:

  1. Martin Volken’s Hazard Evaluator – Pro Guiding Service. December 22, 2013. Accessed August 28, 2024. https://proguiding.com/blog/martin-volkens-hazard-evaluator/
  2. Operational Risk Using the GAR Model. U.S. Fish and Wildlife Service. Accessed August 28, 2024. https://www.fws.gov/sites/default/files/documents/GARModelWorksheet_v20230103.pdf
  3. High Risk, Low-Frequency Events in Public Safety – Today’s Tip from Lexipol.; 2021. Accessed August 28, 2024. https://www.youtube.com/watch?v=pIpRVLkv0rg

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