Hypothermia

Hypothermia is a medical emergency characterized by a core body temperature below the normal range of 95°F (35°C).

Causes of Hypothermia:

1. Increased heat loss

   • Homeless population

   • Elderly patients

   • Submersion injuries

   • Drugs, EtOH, CO poisoning can all cause increased vasodilation, leading to increased heat loss

2. Decreased heat production

   • Endocrine (hypothyroidism, hypoadrenalism, hypoglycemia)

   • Erythrodermas (psoriasis, exfoliative dermatitis, eczema, burns)

   • Impaired shivering

   • Impaired thermoregulation

   • Sepsis

Swiss Hypothermia Staging System:

Stage 1: Mild (32-35°C) - Shivering, mild confusion, awake

Stage 2: Moderate (28-32°C) - Severe shivering, altered mental status

Stage 3: Severe (20-28°C) - Loss of consciousness, bradycardia, shivering may cease

Stage 4: Profound (<20°C) – Unobtainable vital signs

Associated Complications:

1. Cardiac dysfunction

   1. Dysrhythmias can occur when body temperature drops below 30°C

   2. There is typically a drop in temperature and MAP after rewarming is started due to vasoconstriction

2. Cold injuries (frostbite, etc. Maybe there will be more on this at a later date)

3. Coagulopathy (patient may be coagulopathic despite normal labs because the lab rewarms the sample)

   1. Impaired clotting function

   2. Thromboembolism (due to hemoconcentration and poor circulation)

   3. DIC

4. Impaired pharmacology

   1. Protein binding increases when temperature drops, rendering drugs ineffective

   2. Oral meds are not absorbed well due to decreased GI motility

   3. IM route is impaired due to vasoconstriction

5. Rhabdomyolysis

General Management:

1. Airway, Breathing, Circulation (ABCs)

   • Hypothermia causes a leftward shift in oxygen curve so support with oxygen, and prepare for intubation depending on how profound the hypothermia is

2. ECG Findings

   • Patients usually have sinus bradycardia, can progress to a fib with slow ventricular response

   • Severe cases can develop v fib

   • Osborn or "J" waves (associated with moderate to severe hypothermia)
     

3. Remove Wet Clothing - Prevent further heat loss

4. Passive External Rewarming - Insulate the patient, provide warm blankets

5. Active External Rewarming (should be done for moderate hypothermia)

   • Use forced warm air blankets or radiant heaters – our ED uses the Bair Hugger

6. Active Internal Rewarming (for severe hypothermia)

   • Warmed intravenous fluids (warmed to 38-42°C)

• Heated humidified oxygen

• Various lavages (Thoracic, peritoneal, bladder, GI)

Management during Cardiac Arrest:

1. CPR – initiate if patient does not have a pulse (should also assess if patient is still breathing)

   • It is challenging to assess vital signs in hypothermic patients - use end tidal or POCUS to help assist to see if patient is breathing and has cardiac function

   • Starting CPR if the patient does have a pulse may precipitate ventricular rhythms

   • Hypothermic patients have higher chances of improved neurological outcome and survival than normothermic patients that arrest

2. Defibrillation

   • Use defibrillation if indicated, but note that hypothermic patients may not respond to defibrillation until adequately warmed

3. ECMO

   • Patients with refractory hypothermia should be considered for ECMO

   • Patients with out-of-hospital-cardiac-arrest that are hypothermic should ideally be transported to an ECMO center

   • If patient is unstable (dysrhythmia, severe hypothermia, etc) ECMO teams should be contacted early in the ED visit

Stay warm out there this weekend!

Paal P, Pasquier M, Darocha T, Lechner R, Kosinski S, Wallner B, Zafren K, Brugger H. Accidental Hypothermia: 2021 Update. Int J Environ Res Public Health. 2022 Jan 3;19(1):501. doi: 10.3390/ijerph19010501. PMID: 35010760; PMCID: PMC8744717.

Baumgartner EA, Belson M, Rubin C, Patel M. Hypothermia and other cold-related morbidity emergency department visits: United States, 1995-2004. Wilderness Environ Med 2008;19:233-237

Brown et al., Accidental Hypothermia. N Engl J Med 2012; 367:1930-1938

Trauma Tuesday: Electrocution Injuries

 Epidemiology

-       3 primary age groups

o   Toddlers – household sockets, appliances, etc.

o   Adolescents – risk-taking behavior

o   Adults – occupational hazard

-       Lightning strikes – account for 50-300 deaths per year in US (mostly Florida)

-       ~6,500 injuries and 1,000 deaths annually from all electrocution injuries

Classification

-       Low voltage: ≤1000 volts (V)

o   Household outlets in US typically 120 V

-       High Voltage: >1000 V

o   Power lines > 7000 V

-       Alternating current (AC) = electrical source with changing direction of flow  household outlets

o   Induces rhythmic muscle contraction  tetany  prolonged electrocution as individual is locked in place

o   Although generally lower voltages, can be more dangerous than DC as the time of electrocution is much higher

-       Direct Current (DC) = electrical source with unchanging direction of current of flow  lightning strikes, cars, railroad tracks, batteries

o   Usually induces a single, forceful muscle contraction  can throw an individual with significant force  higher risk of severe blunt trauma 

Mechanisms of Injury

-       Induced muscle contraction  rhabdomyolysis

-       Blunt trauma

-       Burns

o   Internal thermal heating – most of damage caused by direct electrocution

o   Flash/Arc burns – electricity passes over skin causing external burns

o   Flame – electricity can ignite clothing

o   Lightning strikes can briefly raise the ambient temperature to temperatures greater than 54,000F

Severity of Injury – is determined by…

-       Type of current – AC vs. DC

-       Duration of contact

-       Voltage

-       Environmental circumstances (rain, etc.)

Clinical Manifestations

-       Cardiac – 15%, mostly benign and occur within few hours of hospital stay

o   Arrhythmias - Most occur shortly after the event, though non-life-threatening arrhythmias can occur a few hours after the event and are usually self-resolving. Generally, …

§  DC = asystole

§  AC = ventricular fibrillation

o   Other EKG findings – QT prolongation, ST elevations, bundle branch blocks, AV blocks, atrial fibrillation

-       Pulmonary

o   Respiratory paralysis – diaphragmatic muscle

o   Blunt trauma – pneumothorax, hemothorax, pulmonary contusions, etc.

-       Neurologic – generally, patient can APPEAR DEAD but is the cause of neurologic electrocution and may be temporary. IE.

o   Coma

o   Fixed, dilated pupils

o   Dysautonomia

o   Paralysis or anesthesia

-       Renal – Rhabdomyolysis

-       Skin – All kinds of burns

-       MSK – from severe muscle contractions

o   Always assume C-spine injury

o   Compartment syndrome

o   Fractures/Dislocations

Management – we’ll divide them into categories of severity. Basically, always do an EKG!!

1)    Mild (<1000V) – examples include brief house outlet shock, stun gun

a.     EKG – other work-up such as troponin and CPK usually unnecessary

b.     If history/physical unremarkable (patient endorses brief contact with house outlet) patient can be discharged without further work-up

c.     If PMH puts patient at higher risk of arrhythmia (cardiac disease, sympathomimetics) can do a brief period of telemetry observation

d.    Can always observe 4-8 hours to be on the safe side

e.     High Risk Features

                                               i.     Chest pain

                                             ii.     Syncope

                                            iii.     Prolonged exposure

                                            iv.     Wet skin

2)    Severe Electrocution (>1000V) – industrial accidents, lightning strikes

a.     Coding – pursue usual ACLS

                                               i.     Keep in mind traumatic causes of arrest (tension pneumothorax, etc.)

                                             ii.     KEY FACT: remember that patients with fixed, dilated pupils, no respiratory effort, and no spontaneous movement may only have TEMPORARY neurologic stunning

                                            iii.     Pursue resuscitation longer than usual as patient with ROSC can still have good outcomes  does not appear to be any definitive guidelines on when to terminate, at physician discretion

b.     Otherwise, broad medical and traumatic work-up and likely admission for telemetry monitoring (basically just send all the labs and images)

                                               i.     Start with primary/secondary trauma survey and further imaging as required

                                             ii.     Don’t forget CPK to assess for rhabdomyolysis

c.     Consider transfer to burn center

TL;DR

-       Treat as you would a trauma/burn patient

-       Most household outlet shocks – history/physical, EKG, and likely quick discharge unless high risk features

-       Industrial shocks – at best admit for telemetry. At worst prolonged ACLS as good outcomes are possible. Don’t forget traumatic causes such as tension pneumothorax

http://brownemblog.com/blog-1/2020/4/14/acute-care-of-the-electrocuted-patient

http://www.emdocs.net/electrical-injury/

http://www.emdocs.net/em3am-electrical-injuries/

http://www.emdocs.net/em-cases-electrical-injuries-the-tip-of-the-iceberg-view-larger-image/

https://www.tamingthesru.com/blog/air-care-series/electrocution

POTD: Tick Bites

 Tick Removal – there are multiple tips and tricks to do this, but most sources suggest…

-       Using a pair of tweezers (or forceps) and attempting to grasp the tick as close to the skin surface as possible

-       Pull upwards with gentle, steady traction. Do not jerk or twist

-       Do NOT squeeze, crush, or puncture the body of the tick – this may expel infectious contents

-       After removing the tick, wash skin thoroughly with soap and water

What to do if mouth parts remain in the skin?

-       UpToDate says to leave it in and they’ll be expelled on their own

-       WikEM says to excise under local anesthesia… seems aggressive

Important Ticks for Identification – The CDC has a good guide. If you’re squeamish with bugs, you’ve been warned and please skip this part. There are 3 main types of ticks found in the US.

1)    Ixodes Scapularis or “deer ticks” = LYME DISEASE. Other ticks do not transmit Lyme disease

-       Brown, about the size of a poppy seed but can be larger when engorged

-       Primarily found in the North-East and Midwest, less commonly in the Western US

-       Most famously transmits Lyme Disease, also anaplasmosis, babesiosis

2)    Dermacentor species or “dog ticks”

-       Brown with a white collar, about the size of a pencil eraser 

-       Primarily found in the Rocky Mountain States (Colorado, Idaho, Montana, Nevada, Utah, Wyoming, etc.)

-       Most known for transmitting, you guessed it, Rocky Mountain Spotted Fever

3)    Amblyomma Americanum or “Lone Star Tick”

-       Brown or black with a white splotch

-       Primarily found in the South, but can also be found in the Eastern US

-       Most known for Southern Tick-associated rash illness (STARI) and ehrlichiosis

Who needs prophylaxis? IDSA recommends prophylaxis only if ALL OF THESE CRITERIA ARE MET. It should be specified that this is for prophylaxis against Lyme Disease only.

-       The tick is identified as a deer tick

-       Tick is estimated to have been attached >36 hours or engorged (it takes time for the bacteria to exit the gut of the tick and enter the bloodstream). Ticks found crawling on skin automatically do not count.

-       The antibiotic can be given within 72 hours of tick removal

-       The bite occurs in a geographic location that Lyme Disease is highly endemic (can be found on CDC website)

-       There is no contraindication to take doxycycline (primarily appears to be hypersensitive or children < 8). If there is a contraindication, no second-line antibiotic exists

The prophylaxis is a single dose of 200mg doxycycline, or 4mg/kg up to a max of 200mg for children.

Antibiotic treatment following a tick bite is not recommended as a means to prevent anaplasmosis, babesiosis, ehrlichiosis, Rocky Mountain spotted fever, or other rickettsial diseases. Rather, patients should be warned and be vigilant against symptoms such as fever, rash, or other symptoms concerning for these diseases.

https://www.cdc.gov/ticks/tickbornediseases/tickID.html

https://www.uptodate.com/contents/what-to-do-after-a-tick-bite-to-prevent-lyme-disease-beyond-the-basics

https://wikem.org/wiki/Tick_borne_illnesses

https://wikem.org/wiki/Tick_removal