Environmental – ED

Environmental

1. Suspect the diagnosis of heat stroke in a patient with altered mental status and fever in a situation of heat stress, and act immediately to reduce the temperature.

1. Prickly heat rash – sweat more than normal leading to blocked sweat glands
2. heat stress – discomfort due to heat
3. Heat Exhaustion – Hyperthermia w/o CNS dysfunction (or mild and resolved with rest/cooling)
4. Heat Stroke – 1) Hyperthermia (>40oC) + 2) CNS dysfunction (H/A, AMS, Sz, Coma, disorientation)
   1. +/- multi-organ failure: elevated CK, rhabdomyolysis, AST – sensitive
   2. +/- shock, ARDS
   3. Classic vs Exertional heat stroke:
      1. epidemic vs isolated event
      2. Nonexertional vs exertional
      3. Elderly vs healthy active athlete
      4. Anhidrosis vs hyperhidrosis
      5. Rarely rhabdo / ATN vs common rhabdo/ATN
   4. Tx: rapidly lower to 39oC and avoid overshooting – causing rebound hyperthemia
      1. Evaporative – spraying water and use of a fan
      2. Ice water immersion
      3. Avoid tylenol/ibuprofen

2. When managing a patient with severe hyperthermia (i.e., at risk for heat stroke), cool the patient promptly and aggressively using multiple effective modalities, before having confirmed any etiological diagnosis, while considering the need to look for etiologies other than environmental heat stress (e.g., neuroleptic malignant syndrome, OD, endocrine, infections).

DDx

• Serotonin syndrome – clonus
• Neuroleptic Malignant Syndrome – rigid
• Malignant Hyperthermia – anesthetic agents
• Endo: Pheochromocytoma, thyroid storm, DKA
• Cocaine / Amphetamine (sympathomimetic OD); ASA OD, TCA OD
• Sepsis / Meningitis / central venous thrombosis / encephalitis – AMS
• TTP – purpura

3. When managing a hypothermic patient, use effective modalities for rewarming, monitor the temperature using an accurate probe, and continue appropriate resuscitation measures until core temperature has recovered.

Hypothermia: mild(35-32) – shivering, mod (32-28), severe <28oC

• osborn wave, bradycardia, atrial fibrillation
• Tx:
  • External
    • Passive rewarming (remove wet clothes & cover w/ warm blanket)
    • Active – bair hugger
  • Internal
    • warm humidified O2, warm IVF
    • invasive: gastric/peritoneal/pulmonary/ bladder lavage with warm NS
    • ECMO
• Continuous temperature monitor with esophageal or rectal probe

4. Recognise that pain and other unexplained symptoms after diving could be dysbarism in origin, and refer the patients for hyperbaric therapy when appropriate.

1. Air Embolism – PE/MI/CVA within 10min of surfacing

• PFO/septal defects more susceptible
• 1. Cerebral embolization – CVA / blindness / Sz / confusion
• 2. Coronary artery embolization – ACS findings
• Tx: L lateral decubitus with trendelenburg, ABC, 100% O2, IVF and rapid recompression in Hyperbaric O2

2. Decompression sickness – N2 in tissue / vessels

• length and depth of dive main determinants
• >10min after surfacing occur up to 12 hours later – “air travel after diving”
• Type 1 DCS – the bend: periarticular pain, pruritus, erythema, cutis marmorata (venous stasis), LOC uncommon
• type 2 DCS – serious: CNS (AMS), Spinal cord (paralysis), Inner ear (ataxis) “staggers”, Lung (PE) “the chokes”
• Tx: Supine position, IV hydration, 100% oxygen, rapid recompression in hyperbaric oxygen

Nitrogen Narcosis – at depth >100ft

• anesthetic effect, impaired motor control, LOC
• recovers rapidly upon ascent

5. In patients presenting following an electrical injury, consider and look for internal injuries (including myocardial) and associated trauma that are not apparent from external signs, and monitor appropriately until the risk of complication is mitigated.

Increase resistance produces increased heat:

• Bone>fat >tendon>skin>>>muscle>blood>nerve – current flows thru NN, blood vessels, muscles causing deep crush injury
• AC more severe injuries than DC
  • AC exit = entrance; DC exit >entrance (throw pt away)

Associated injury

• Neuro – brain injury w/ loss of respiratory drive
• Myocardium
• Rhabdomyolysis
• From the fall afterward
• Posterior shoulder dislocation
• Lightening – Lichtenberg “ferning” – superficial burns, ruptured TM, fixed pupils (autonomic dysfunction)
• Delayed labial artery bleed in children who chew on electrical cords (day 5 when scar falls off)
• DC current – Asystole;
• AC current: more lethal – A Fib