Spider Bites

The brown recluse spider, scientifically known as Loxosceles reclusa, is known for its venomous bite. This spider is found in southern US states.

1. Mechanism of Toxin: Sphingomyelinase D causes hemolysis and complement mediated erythrocyte destruction. There are multiple proteases that break down collagen, elastin, fibrinogen, etc and act synergistically with sphingomyelinase D to cause local tissue destruction

2. Clinical Features of Bites:

   • Course of bite: The bite is often painless or with minimal pain. There will be two small puncture wounds. This will become pale with the edges becoming red. Over the next few days, this turns into a blister with a central ulcer, followed by skin sloughing. Can take weeks for wound to heal.

   • Early Symptoms (2-8 hours):

     • Redness and swelling around the bite site

     • Mild to moderate pain and itching

   • Delayed Symptoms (12-36 hours):

     • Necrotic (dead) tissue formation, leading to an ulcer

     • Systemic symptoms like fever, chills, malaise, headache, nausea

   • Worsening complications:

     • DIC

     • Rhabdo

     • Kidney Failure

3. Evaluation: Lab tests should only be ordered in patients with systemic symptoms and fear of worsening complications. Should order CBC, CMP, CK, retic count, haptoglobin, LDH, PT/INR, D-dimer, fibrinogen.

4. Medical Management:

   • Local Wound Care: Primary management is local wound care. Clean the site with soap and water, apply a cold compress to reduce swelling, and elevated the affected site. Sphingomyelinase D also has reduced activity in lower temp, so ice packs are important! Patient should also receive tetanus prophylaxis!

   • Pain Management: NSAIDs

   • Wound Care for Necrotic Tissue: If wound is severe enough, may require eval for debridement and potential skin grafting (this is usually weeks later). Hyperbaric oxygen therapy can also be considered for severe cases.

   • Antibiotics: Only if concern for local cellulitis.

   • Systemic Treatments: Weak evidence for use of dapsone. There is slightly more evidence behind the use of corticosteroids for reducing the risk of AKI and rhabdo.

It's crucial to note that brown recluse spider bites are rare, and most cases resolve with local wound care.

Black widow spiders, known as Lactrodectus spp, are venomous arachnids found in various regions around the world. The venom they produce contains neurotoxins, primarily alpha-latrotoxin, which affects the nervous system. These spiders classically have the “red hourglass” marking on them.

1.       Mechanism of Toxin: The primary toxin in black widow spider venom is alpha-latrotoxin. It works by binding presynaptic neurons, creating calcium permeable channels in the lipid layers, causing an influx of calcium into the presynaptic cells. This leads to an excessive release of neurotransmitters. Primarily concerned with release of acetylcholine.

2.       Clinical Features of Bites:

• Course of bite: Bites are often initially characterized by severe local pain at the bite site. Very quickly patients will develop erythema and edema at site of bite

• Systemic Symptoms: As the venom spreads, systemic symptoms may develop, including muscle pain and cramps, abdominal pain, weakness, sweating, and nausea. Patients may experience autonomic nervous system effects such as increased blood pressure and heart rate.

• Worsening complications

  • Rhabdo

  • Myocarditis

  • A-fib

3.     Laboratory Tests: Lab values are generally nonspecific for black widow bites. Patients will tend to have elevated WBC, hematuria, and elevated liver enzymes. There are documented cases of rhabo and myocarditis from black widow bites, and there for kidney function and troponins can be checked if patients complain of systemic symptoms.

4.       Medical Management:

• Local Wound Care: Clean the site with soap and water. Patient should also receive tetanus prophylaxis!

• Pain Control: Analgesics, such as opioids or muscle relaxants, may be used to manage pain.

• Antivenom: In severe cases or when systemic symptoms are significant, antivenom may be administered. This can rapidly reverse the effects of the venom. It is horse derived, and may cause anaphylaxis.

• Observation: Patients may be observed for several hours to ensure symptoms do not worsen and to monitor for potential complications. Consider admission in children, patients with preexisting cardiac conditions, pregnant women, or for severe symptoms.
  
  It's important to note that while black widow spider bites can be painful and cause distressing symptoms, fatalities are rare.
  
   
  
  Anoka IA, Robb EL, Baker MB. Brown Recluse Spider Toxicity. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537045/
  
  Williams M, Sehgal N, Nappe TM. Black Widow Spider Toxicity. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499987/
  
   

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