Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Immediate priorities
Stabilization and triage
Airway compromise
If depressed mental status, airway protection
If aspiration risk, suction and positioning
Breathing compromise
If hypoventilation, assisted ventilation
If hypoxia, supplemental oxygen
Circulation compromise
If shock, isotonic crystalloid bolus and reassessment
If dysrhythmia, ACLS pathway
Hypothermia screening and management
Core temperature measurement
If moderate to severe hypothermia, active core rewarming and continuous monitoring
Concurrent trauma and cold injury coassessment
If polytrauma, trauma pathway and imaging
If compartment syndrome concern, urgent surgical consultation
Limb threat assessment
Limb viability and time sensitivity
Time from cold exposure to rewarming
Time of freezing
Any refreezing episodes
After rewarming perfusion assessment
Capillary refill
Doppler signals
Sensation and motor function
If absent perfusion after rewarming, urgent burn or vascular consultation
Thrombolysis or vasodilator candidacy window assessment
Transfer to center with frostbite capability
Rapid rewarming decision
Rewarming strategy selection
If risk of refreezing, delay active rewarming until refreezing risk eliminated
If no refreezing risk, rapid water bath rewarming
Water temperature 37 to 39 C
Duration 15 to 30 minutes
Analgesia requirement during rewarming
If severe pain, opioid analgesia
Severity classification and documentation
Frostbite staging
Frostnip
Transient pallor and numbness
No tissue freezing
Superficial frostbite
Skin freezing
Clear blisters possible
Deep frostbite
Full thickness tissue freezing
Hemorrhagic blisters possible
Cauchy frostbite grading for prognosis
Grade 1
Grade 2
Grade 3
Grade 4
Photodocumentation
Pre rewarming appearance
Post rewarming appearance
Blister type and distribution
History
Key history elements
Exposure and timeline
Duration of cold exposure
Continuous exposure duration
Intermittent exposure
Wet exposure
Immersion
Sweating under clothing
Wind exposure
Wind chill context
Inadequate insulation
Rewarming attempts
Method used
Any refreezing after rewarming
Symptoms and functional impact
Numbness
Persistent after rewarming
Paresthesia
Pain
During rewarming
Persistent pain after rewarming
Color change
Pallor
Cyanosis
Erythema after rewarming
Swelling and stiffness
Limited ROM
Loss of grip or ambulation
Risk factors
Alcohol use
Intoxication at exposure
Impaired thermoregulation
Substance use
Sedatives
Stimulants
Smoking or nicotine
Vasoconstriction risk
Diabetes mellitus
Neuropathy
Microvascular disease
Peripheral arterial disease
Claudication history
Prior revascularization
Raynaud phenomenon or connective tissue disease
Cold induced vasospasm history
Prior cold injury
Recurrent frostbite susceptibility
Associated illness and injury
Hypothermia symptoms
Confusion
Ataxia
Dehydration and starvation
Poor intake
Exhaustion
Trauma
Falls
Crush injury
Trench foot or nonfreezing cold injury exposure
Prolonged wet cold without freezing
PITFALLS
Common pitfalls
Underestimating deep frostbite before rewarming
Tissue demarcation delayed days to weeks
Rewarming when refreezing possible
Refreezing increases tissue loss risk
Rubbing or dry heat exposure
Mechanical and thermal injury risk
Physical Exam
General and systemic
System assessment
Core temperature status
Hypothermia category
Shivering presence
Hemodynamic status
Heart rate and rhythm
Blood pressure trend
Mental status
Confusion
Intoxication signs
Coexisting cold injury
Hypothermia features
Nonfreezing cold injury features
Local extremity exam
Affected part exam
Skin appearance
Waxy or wooden feel
Mottling
Cyanosis
Blister characterization
Clear blisters
Hemorrhagic blisters
Perfusion
Capillary refill after rewarming
Doppler arterial signals
Sensation
Light touch
Two point discrimination if hand involvement
Motor function
Active ROM
Weakness suggesting deep injury
Edema pattern
Circumferential swelling
Distal to proximal progression
Compartment syndrome screening
Pain out of proportion
Pain with passive stretch
Tense compartments
PITFALLS
Exam pitfalls
Early pulses do not exclude microvascular thrombosis
Perfusion reassessment after rewarming
Pain masked by neuropathy or intoxication
Low threshold for perfusion imaging in high risk patients
Differential Diagnosis
Primary and mimics
Cold injury differential
Frostnip
ICD-10 T33.0 to T33.9 for superficial freezing injury by site
SNOMED CT concept: Frostnip
Frostbite
ICD-10 T33 and T34 series by site and depth
SNOMED CT concept: Frostbite
Nonfreezing cold injury
Trench foot
Chilblains
Cold induced urticaria or vasospasm
Raynaud phenomenon
Acrocyanosis
Vascular and ischemic mimics
Acute limb ischemia
Embolic occlusion
Thrombosis in situ
Severe peripheral arterial disease exacerbation
Critical limb ischemia
Vasculitis
Small vessel vasculitis
Cryoglobulinemia
Dermatologic and infectious mimics
Cellulitis
Warmth and erythema predominance
Necrotizing soft tissue infection
Rapid progression
Systemic toxicity
Contact dermatitis or chemical burn
Exposure history
Sharp demarcation
Trauma related
Crush injury
Rhabdomyolysis risk
Fracture or dislocation
Deformity
Point tenderness
Laboratory Tests
Initial labs and indications
Baseline laboratory evaluation
Point of care glucose
Hypoglycemia as hypothermia mimic
Hyperglycemia in diabetes and stress response
Complete blood count for infection or hemoconcentration
Leukocytosis interpretation with stress response
Hemoconcentration with dehydration
Electrolytes and renal function
Potassium disturbances in hypothermia
Creatinine for contrast planning
Creatine kinase for muscle injury and rhabdomyolysis
Trend for crush or prolonged cold immobilization
AKI risk stratification
Liver enzymes if systemic hypoperfusion concern
Shock liver consideration
Alcohol related injury
Coagulation studies if thrombolysis considered
INR
aPTT
Pregnancy test when applicable
Medication safety planning
Radiation planning
Blood gas if significant hypothermia or respiratory compromise
pH and PaCO2
Lactate as perfusion marker
Thrombolysis readiness labs
Thrombolysis and vasodilator pathway labs
Platelet count threshold planning
Bleeding risk stratification
Procedure planning
Fibrinogen baseline if tPA pathway
Bleeding risk marker
Monitoring during infusion
Type and screen if high bleeding risk interventions
Possible transfusion planning
Procedural support
PITFALLS
Lab pitfalls
Normal early labs do not exclude deep tissue necrosis
Serial clinical reassessment
Delayed demarcation expectation
Elevated CK with prolonged exposure without obvious crush
Immobilization rhabdomyolysis consideration
Aggressive hydration if indicated
Diagnostic Tests
Scoring Systems
Prognostic scoring and staging
Cauchy clinical grading
Grade 1
Distal phalanx involvement only
No cyanosis after rewarming
Grade 2
Intermediate phalanx or more proximal involvement
Cyanosis limited to distal segment
Grade 3
Proximal involvement with persistent cyanosis
Hemorrhagic blisters possible
Grade 4
Extensive proximal involvement
Likely tissue loss
Use of grade for therapy selection
If grade 2 to 4, consider iloprost pathway
If grade 3 to 4 with absent perfusion, consider thrombolysis pathway
MRI
MRI role
Soft tissue viability assessment
Deep tissue necrosis extent
Osteomyelitis evaluation in delayed presentations
Limitations
Limited acute prognostic value early
Availability and time constraints in ED setting
CT
CT role
CT angiography when acute limb ischemia alternative diagnosis
Large vessel occlusion assessment
Revascularization planning
Limitations
Microvascular thrombosis not fully characterized
Contrast nephropathy risk in dehydration
Ultrasound (or US)
Ultrasound role
Duplex Doppler assessment
Macrovascular flow documentation
Serial perfusion reassessment
POCUS for complications
If compartment syndrome concern, adjunctive assessment
If hypothermia related cardiac dysfunction, bedside echo
Disposition
Level of care and referral
Disposition planning
Admission indications
Deep frostbite suspected
Persistent absent perfusion after rewarming
Significant hypothermia
Rhabdomyolysis risk or AKI
Uncontrolled pain
Infection concern or immunocompromise
Specialty consultation triggers
Burn center consultation for deep frostbite or multi digit involvement
Vascular or interventional radiology for perfusion deficits and thrombolysis consideration
Orthopedics or hand surgery for severe involvement
Transfer criteria
Candidate for iloprost or thrombolysis not available locally
Need for advanced imaging or surgical capability
Discharge criteria
Frostnip or superficial frostbite only
Normal perfusion after rewarming
Reliable follow up and wound care capacity
Follow up
Follow up and monitoring
Early recheck within 24 to 72 hours for progression
Perfusion reassessment
Blister evolution
Longer term follow up
Tissue demarcation monitoring over weeks
Rehab and ROM therapy planning
Treatment
Rewarming and immediate care
Core and local rewarming
Rapid water bath rewarming for frozen part
Water temperature 37 to 39 C
Duration 15 to 30 minutes
Continue until tissue pliable and erythematous
Prevent refreezing
Warm environment and insulation
Avoid re exposure until definitive warming assured
Analgesia during rewarming
Opioid analgesia if severe pain
Regional anesthesia consideration for extensive injury
General measures and wound care
Supportive and local care
Gentle handling and protection
Bulky dry dressings
Elevation to reduce edema
Blister management
Clear blisters
Debridement consideration in burn specialist pathway
Infection risk and dressing planning
Hemorrhagic blisters
Leave intact in most protocols
Specialist guided debridement if needed
Topical therapy
Aloe vera every 6 hours if available
Nonadherent dressings
Tetanus prophylaxis
If immunization not up to date, tetanus vaccination
If high risk wound and unknown status, tetanus immune globulin
Anti inflammatory and antiplatelet strategy
NSAID based prostaglandin inhibition
Ibuprofen
12 mg/kg/day by mouth divided every 6 to 8 hours
Maximum 2400 mg/day
Continue until healing or demarcation
If NSAID contraindicated, specialist directed alternative
GI bleed risk
Renal dysfunction
Infection management
Antibiotic strategy
No routine prophylactic antibiotics for uncomplicated frostbite
Low infection rate without necrosis
Focus on wound care and monitoring
If cellulitis or infected necrosis, antibiotics per local SSTI guidance
MRSA risk assessment
Culture if purulence
Thrombolysis and vasodilator therapy
Reperfusion targeted therapies for deep frostbite
Candidate selection after rewarming and perfusion assessment
Deep frostbite with absent distal perfusion
Significant digit or limb involvement
Contraindications screening for thrombolysis
Active bleeding
Recent stroke
Recent major surgery
Intracranial pathology
Iloprost pathway
Indication pattern
Cauchy grade 2 to 4 within 48 hours of injury
Persistent ischemia after rewarming
Dosing and administration
Initiate iloprost IV 0.5 ng/kg/min
Titrate every 30 minutes to 2 ng/kg/min as tolerated
Duration 6 hours daily
Course 5 to 8 days
Monitoring
Blood pressure every 15 minutes during titration
Headache and flushing as dose limiting effects
Evidence level labeling
Consensus guideline support for grade based use
ACEP Level C style evidence statement
Thrombolysis pathway with alteplase
Indication pattern
Deep frostbite with absent perfusion after rewarming
Presentation within 24 hours of injury when feasible
Example institutional protocol framework
Catheter directed alteplase
Initiate alteplase 0.5 mg/hour per affected limb vascular territory
Titrate up to 1 mg/hour based on perfusion response and bleeding risk
Typical duration 6 to 24 hours
Concurrent heparin infusion
Initiate heparin 500 units/hour
Titrate to aPTT target per institutional protocol
Monitoring
Neuro checks every 1 to 2 hours
Hemoglobin and fibrinogen every 6 hours
Systemic alteplase
Use only with specialist protocol if catheter access unavailable
Bleeding risk higher than catheter directed approach
Post thrombolysis antithrombotic plan
Transition plan per consultant
Ongoing perfusion checks
Evidence level labeling
Class IIb recommendation style for selected patients in specialized centers
ACEP Level C style evidence statement
Adjunctive therapies not routinely recommended
Hyperbaric oxygen
Insufficient evidence for routine use
Consider only in specialist driven protocol
Surgical and delayed care principles
Surgical timing and tissue demarcation
Early amputation avoidance
Demarcation over weeks typical
Early surgery increases tissue loss risk
Early surgery exceptions
Wet gangrene
Sepsis source control
Compartment syndrome
Escharotomy or fasciotomy
If compartment syndrome, urgent decompression
If circumferential constriction with perfusion compromise, specialist decision
Special Populations
Pregnancy
Pregnancy considerations
Maternal hypothermia risk prioritization
Active core rewarming when indicated
Fetal monitoring coordination when viable gestation
Medication considerations
NSAID avoidance in later pregnancy context
Opioid analgesia risk benefit discussion
Thrombolysis and iloprost
Specialist consultation mandatory
Maternal bleeding risk assessment
Disposition bias toward observation or admission
Lower threshold for monitoring
Coordination with obstetrics
Geriatric
Geriatric considerations
Higher comorbidity burden
Peripheral arterial disease prevalence
Anticoagulant and antiplatelet use
Medication dosing and toxicity
NSAID renal and GI risk
Opioid delirium risk
Lower threshold for admission
Hypothermia complications
Social support limitations
Pediatrics
Pediatric considerations
Faster heat loss physiology
Hypothermia co injury risk
Core temperature monitoring priority
Weight based dosing
Ibuprofen 10 mg/kg by mouth every 6 to 8 hours
Maximum daily dose per local pediatric guidance
Rewarming approach
Water bath 37 to 39 C with continuous supervision
Pain control planning with pediatric dosing
Specialist consultation thresholds
Multi digit involvement
Deep frostbite suspicion
Background
Epidemiology
Epidemiologic context
High risk settings
Outdoor recreation and occupational exposure
Unsheltered homelessness
Common sites
Fingers and toes
Nose and ears
Risk modifiers
Wind and wet exposure
Tight footwear and impaired circulation
Pathophysiology
Mechanisms of injury
Ice crystal formation and cellular injury
Extracellular ice leading to osmotic shifts
Cellular dehydration and membrane damage
Microvascular dysfunction
Endothelial injury
Thrombosis and no reflow
Reperfusion injury
Inflammatory mediator release
Progressive tissue necrosis after rewarming
Blister fluid mediator content
Thromboxane and prostaglandins contribution
Rationale for NSAID and aloe vera use
Therapeutic Considerations
Rationale for key therapies
Rapid rewarming
Limits duration of tissue freezing
Improves microvascular flow
NSAIDs
Decrease prostaglandin and thromboxane mediated thrombosis
Pain control adjunct
Thrombolysis and vasodilators
Target microvascular thrombosis and vasospasm
Time dependent benefit
Delayed surgical decisions
Tissue viability declares over time
Early amputation increases avoidable tissue loss
Patient Discharge Instructions
copy discharge instructions
Discharge instructions
Wound care
Keep area clean and dry
Nonadherent dressing changes daily or if wet
Elevation when resting
Activity
Protect from pressure and friction
Avoid smoking or nicotine
Pain control
Ibuprofen as directed if safe
Avoid excess heat sources
Avoid refreezing and cold exposure
Warm clothing and gloves
Avoid outdoor exposure until healed
Return to ED now for red flags
Increasing pain not controlled
New numbness or weakness
Skin turning black or rapidly worsening discoloration
Spreading redness, pus, fever, or chills
Blisters rapidly increasing or foul odor
Follow up
Recheck in 24 to 72 hours
Burn or hand specialist follow up if blistering or fingertip involvement
References
Clinical guidelines and evidence sources
Frostbite guidance sources
Wilderness Medical Society clinical practice guidelines on prevention and treatment of frostbite
Rapid rewarming 37 to 39 C recommendation
Ibuprofen for prostaglandin inhibition recommendation
American Burn Association referral principles for complex extremity injury care
Burn center involvement for deep frostbite and multi digit injury
Transfer considerations for limb salvage therapies
Specialty consensus on thrombolysis for selected deep frostbite in specialized centers
Time window based selection
Bleeding risk and monitoring requirements
ACEP Level C evidence style labeling for frostbite therapies commonly based on consensus and observational data
Iloprost use in selected grade based cases
Thrombolysis in selected deep frostbite cases
Class IIb recommendation style statement for thrombolysis in selected patients when expertise available
Benefit may exceed risk in carefully selected cases
Shared decision making and specialist oversight
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.