FROSTBITE

1. FROSTBITE Kathryn Moser, RN, MSN, AGACNP, EMT-B University of Colorado Hospital

2. Objectives • Define frostbite • Discuss contributing factors • Describe the progression of frostbite injury • Name strategies to minimize risk of frostbite • Review how to recognize and diagnose frostbite • Discuss the treatment of frostbite • Identify long-term effects and prognosis • Discuss challenges unique to alpine environment

3. Frostbite

4. What is Frostbite? • Injury to the skin and underlying tissues as a result of environmental cold exposure

5. Mechanism of Injury • Cooling of tissue and vasoconstriction = decreased sensation or numbness • Ice crystals form inside (fast) or outside cells (slow) causing damage to cell membranes and eventual cell death • Cycles of vasoconstriction and dilation cause lack of oxygen to tissues and clot formation • Tissue hypoxia results in tissue death, clot formation, and inflammation through release of chemical mediators • Damage is increased if refreezing occurs

6. Contributing Factors

7. Environmental Factors • Temperature, Windchill and Length of Exposure

8. Individual Factors: Clothing • “Frostbite is more likely to happen to uncovered skin” • Tight-fitting clothing may produce constriction  hinders blood circulation • Wet clothing transmits heat from the body into the environment

9. Individual Factors: Comorbidities • Disease states that alter tissue perfusion may predispose to frostbite • Diabetes, Atherosclerosis, Neuropathies…

10. Individual Factors • Drugs/Alcohol/ Smoking • Putting on clothes in response to cold requires a conscious decision • Alcohol promotes peripheral vascular dilation and increases heat loss  more susceptible to frostbite • interferes the body’s ability to regulate temperature by blunting the shiver reflex • Smoking causes vasoconstriction and decreases circulation

11. Individual Factors • Unique to the alpine environment • Altitude – baseline hypoxia • Concurrent trauma • Hypothermia • Dehydration/poor nutrition • Not having adequate expertise for the environment (lacking a guide)

12. Recognizing and Diagnosing Frostbite

13. The anatomic sites most susceptible to frostbite include: • Hands • Feet • Exposed tissues • Ears • Nose • Lips

14. Diagnosing Frostbite • Several diagnostic tests have been used to attempt to predict severity and prognosis of frostbite injury • Plain radiographs • Infrared thermography • Angiography • Bone scanning • Laser Doppler • Digital plethysmography • MRI/MRA

15. Early Signs and Symptoms • Shivering is the first sign the body is losing heat • Tingling and burning are also early signs to get out of the cold or move around vigorously

16. Late Signs and Symptoms • Numbness (>75%) • Purplish blood-filled blisters • White or grayish-yellow skin area • Skin that is unusually firm or waxy

17. Classifying Frostbite • Superficial frostbite injury • numbness and redness • White, yellowishor gray firm plaque in the area of injury • Clear or milky fluid in blisters • No tissue loss

18. Classifying Frostbite • Deep Frostbite Injury • Purple, blood-containing fluid filled blisters (after re-warming) • Skin feels hard and cold • Injury has extended through a variable portion of the dermis or may even involve muscle and bone

19. Frostbite! Now What?

20. Treatments and Interventions…in the field • First priority is do no further harm • Remove jewelry and wet/cold clothing • Treat the hypothermia • Avoid walking on frostbitten feet or toes • But… it is better to walk with frozen feet than to attempt to rewarm and then freeze again and if it is the only way to evacuate… • Avoid thawing an affected area if you suspect refreezing • Don’t rewarm in the field, unless you can keep it thawed

21. Rewarming • Rapid rewarming is the single most effective therapy for frostbite • Rewarm the frostbitten area if there is no danger of refreezing • Rewarming should be avoided if it cannot be maintained (freeze-thaw-freeze cycle) 

22. Rewarming “Do’s” • Do: rapidly rewarm the affected area in circulating water at 37-39 degrees C (99-102 degrees F). • Do: Continue warming for 15-30 minutes (up to 1 hour for deep frostbite injuries) until thawing is complete on clinical assessment • Clinical assessment: distal area of the extremity is flushed, soft, and pliable

23. Rewarming “Dont’s” • Don’t: end the rewarming process prematurely because of reperfusion pain (may need narcs) • Don’t: use mechanical trauma (massaging or rubbing the area with snow or warm hands) • Don’t: rewarm at higher temperatures • Don’t: use dry heat (using a fire, heater/heating pad, exhaust, or a stove) • This can lead to burns • Don’tdrain blisters unless is necessary and are clear

24. Pharmacologic Treatments and Interventions • Analgesics for pain relief are indicated during and after rewarming • Topical aloe vera cream is implicated to inhibit the arachidonic cascade, especially thromboxane synthesis • t-PA

25. The next step is.. • Transfer to a hospital/clinic familiar with the treatment of frostbite while protecting from cold • Keep extremity elevated • No weight bearing • Update tetanus • Analgesia – Ibuprofen and may need narcotics

26. Inpatient Non-Pharmacologic Treatment and Interventions • Rapid rewarming of affected area (if not done) • Vascular checks every hour • Pain management • Wound care- supportive • focused on maintaining a clean wound environment to protect skin from further damage • Surgical intervention including the possibility of amputation • Physical therapy to prevent long term contracture or dysfunction • Rehabilitation

27. It’s not just amputation anymore, but what works? • NSAIDS – Ibuprofen, Aspirin, Naproxen block the inflammatory mediators • Vasodilator therapy (Alaska method) – improve blood flow • Iloprost (prostaglandin)– not FDA approved for frostbite • Dextran – fix the dehydration • t-PA – bust the clots • Hyperbaric oxygen therapy – get more oxygen • ALL of these methods are supported by some evidence, but not one is clearly documented by research to be the best therapy.

28. What am I supposed to do? • References such as the Alaska Cold Injuries Guidelines and Wilderness Medical Society Frostbite Practice Guidelines have some suggestions and levels of evidence for recommendations. • This began a discussion at University of Colorado Hospital..

29. Local Problem • Complications from frostbite injuries can be devastating and include permanent damage and/or amputation to the affected tissue or limb • Literature reports the incidence of digital amputation to be more than 40% without effective treatment.

30. Local Problem • Standardized protocols were lacking for treatment of severe frostbite • Treatment for frostbite injuries typically included: • rewarming • antibiotics • topical creams • amputation • watching and waiting

31. Step 1: Literature Review

32. Current Evidence • The use of t-PA as a thrombolytic for the treatment of frostbite has been documented in two small, single-center studies1, 3 • University of Utah (Bruen et al., 2007) • Hennepin County Medical Center (Twomey, Peltier, & Zera, 2005) • T-PA improved revascularization by dissolving clots • T-PA assisted in restoring tissue perfusion minimizing the adverse effects of frostbite

33. Current Evidence • Both studies supported the use of t-PA to decrease progression of frostbite injury to amputation • Bruen et. al. (2007) showed a 10% incidence of amputation in patients who received t-PA within 24 hours of injury compared to 41% in patients who did not receive t-PA

34. Background on T-PA • T-PA has been approved by the FDA for management of: • acute myocardial infarction • acute ischemic stroke • acute massive pulmonary embolism • Due to it’s mechanism of action, t-PA comes with high risk for bleeding, requiring specific contraindications and dosing parameters for safe administration.

35. Development of Standardized Therapy • Was a process that took 2 years • Involved all members of the Burn Team • Including developing standardized protocol, order sets, and guidelines • We started collecting data on frostbite outcomes as part of a quality improvement project

36. Indications 1. Absent or weak doppler pulses in limbs and/ or digits and no improvement on rapid rewarming OR no perfusion on bone scan 2. Within 24hrs of frostbite injury *Note: BP must be less than 180 systolic and 105 diastolic prior to initiating infusion

37. Contraindications 1. Concurrent or recent trauma, stroke or bleeding 2. Recent surgery or hemorrhage 3. Multiple freeze-thaw cycles 4. More than 48 hours of cold exposure 5. Severe uncontrolled hypertension (systolic blood pressure greater than 185mmHg and/or diastolic blood pressure greater than 110mmHg) 6. Pregnancy 7. Current anticoagulant therapy (INR greater than 3) 8. Thrombocytopenia (platelets less than 100x109/L ) 9. History of gastro-intestinal bleeding

38. T-PA Dosing

41. N=10

42. Complications • No significant bleeding complications since the implementation of this protocol • 1 patient had bilateral thigh hematomas and 1 patient had a hematoma on forehead without a bleed on CT • No transfusions required • T-PA did not have to be stopped after initiating administration

43. Conclusions • Amputation rate lowered • 22-31% in patients not eligible for t-PA • 0-0.2% in patients who received within 48 hours • Administration of thrombolytics dramatically reduces the rate of amputation in patients with severe frostbite • New data is emerging to suggest that t-PA is most effective within 6 hours after injury.

44. SEQUALE AND PROGNOSIS

45. Frostbite Sequale • Throbbing pain begins 2 to 3 days after rewarming and continues for a variable period, even after dead tissue becomes demarcated (can take up to 6 months) • In patients without tissue loss, symptoms usually subside within 1 month • Cold sensitivity • Sensory loss • Hyperhidrosis

46. Prognosis • Complications from frostbite injuries can be devastating and include permanent damage and/or amputation to the affected tissue or limb • Literature reports the incidence of digital amputation to be more than 40% without effective treatment

47. Future Directions

48. Hyperbaric Medicine • Increase RBC deformability • Decreases edema • Improves nutritive skin blood flow • Improves oxygenation • Helps to reverse the reperfusion injury • Promising case studies

49. Hyperbaric Medicine • Hyperbaric oxygen treatment in deep frostbite of both hands in a boy • 11 yo boy, severe frostbite 6 fingers • 2 weeks hyperbaric treatment

50. Hyperbaric Medicine • Frostbite in a Mountain Climber Treated with Hyperbaric Oxygen: Case Report • 28 yo female mountain climber • 10 finger involvement • Delay treatment of 2 weeks • Hyperbaric treatment over 3 months (21 treatments)