Hypothermia & Local Cold Injuries

Transcription

1 Sacred Heart Medical Center and Children s Hospital Hypothermia & Local Cold Injuries Objectives Types of heat loss Describe mechanisms of injury for hypothermia and local cold injuries Discuss pre-hospital and hospital treatment of hypothermia Discuss pre-hospital and hospital treatment of local cold injuries Radiation Heat transferred from one structure to another without heating air Sunshine on a cold, winter day Convection Heat transferred to air around body or structure Infra-red thermogram of body heat Significant of heat loss with air movement Types of heat loss Thermoregulation Evaporation Heat transferred to water molecules then evaporate Sweating when exercising Significant of heat loss with air movement Conduction Heat transferred directly between bodies or structures Patient laying on a cold, tile floor for hours Up to 35 X greater loss in water compared to air Normal temp 98.6 F Normal range = 96.9 to 99.9 F Normal temperature required for body s chemical reactions to function Core temperature variations Lower in the morning Higher in the early afternoon Higher in women during some parts of menstrual cycle 1

2 Thermoregulation Peripheral thermoreceptors Entire outer surface of body More in upper torso Fewer in lower torso Fewer still in lower limbs Sends signals to hypothalmus Central thermoreceptors in: Abdominal organs Spinal cord Hypothalamus All provide temperature input to hypothalamus Thermoregulation Hypothalamus Integrates input from both peripheral and central inputs Maintains core temperature Core temp = sweating Core temp = cold response Vascular response Vasoconstriction Shunts blood from cold areas Preserves core temperature Ability to constrict affected by sunburn for up to one week Drop in blood pressure with immersion rescue Thermoregulation Evaporation suppressed Metabolic response Increase REQUIRED to maintain core temperature Metabolic rate will by 4% for every of 1 F in core Metabolic response Glucose stores mobilized, then quickly depleted if not replenished Shivering may triple oxygen consumption Thermoregulation Neurological response Enzyme function sensitive Usually first system impaired Changed personality/behavior Poor memory or judgment Slurred speech Decreased consciousness Nerve chilling shivering Cardiovascular response myocardial O 2 consumption Cardiac output will Heart rate will and then If patient is tachycardiac with hypothermia, look for another cause 2

3 Thermoregulation Cardiovascular response Conduction more sensitive PR, QRS, QT interval increased Shivering may obscure P wave All types of arrhythmias found J wave (Osburn wave) Cardiovascular response J wave (Osburn wave) May occur in core temp 90 F Most commonly found in II/V 6 When core temps are below 77 F, may be found in V 3 & V 4 J-Wave (Osburn Wave) Thermoregulation Respiratory response Increased rate, followed by depression 5 10 breaths/minute with core temperature 86 F Chest wall loses elasticity Hypoxia increased by cold Renal response Vasoconstriction central vascular volume volume = diuresis Immersion U/O by 3.5 X Alcohol can double this!!! Thermoregulation Coagulation response Enzyme malfunction causes clotting problems Platelets become inactive Diuresis leads to hemoconcentration RBCs lose ability to deform Risk Factors Exhaustion Glucose stores exhausted No glucose for shivering Hypoglycemia decreases temperature for shivering threshold Immobilization Unable to generate heat Includes entrapment Meds affecting glucose Beta blockers Steroids Oral anti-hyperglycemics Risk Factors Alcohol Affects judgment and decision making capability May heat loss through vasodilitation, not proven Creates hypoglycemia Hypoxia Decreases regulated core temperature Inadequate clothing Simplest way to prevent Affected by: Windchill Wet clothing 3

4 Risk Factors Spinal cord injuries Acute injury may cause spinal shock vasodilitation Lack of movement decreases heat generation by movement Age Infants Lack of ability to shiver until about 2 years of age Generate heat from brown fat Premature babies lack substantial brown fat = greater risk for hypothermia Large head size radiates heat Risk Factors Age Children Activity usually generates a substantial amount of heat Large head size radiates heat Age Elderly Decreased fat & insulation Decreased muscle mass Decreased vascular response to cold Impaired thermal perception Medication interactions Risk Factors Medical conditions Any condition that body reserves Cardiac Respiratory Diabetes Environmental acclimation Repeated exposure = risk Lack of acclimation = risk Windchill - heat loss from: Convection Evaporation Windchill Chart Risk Factors Dehydration Increase risk Better to drink cold water Physical condition ability to respond to stress Poor conditioning risk TRAUMA! Often seen with hypothermia stress response capability May be overlooked Caused by examination or treatment? Causes coagulation disorders TREAT ALL TRAUMA PATIENTS AS IF THEY ARE HYPOTHERMIC! 4

5 Patient Assessment Thermometers Mercury type More subject to error Accurate scale? Has it been shaken down? Remain in place for 3 minutes? Use electronic types Esophageal most accurate Oral temperatures Mouth MUST remained closed Affected by: Eating Smoking Fluid intake Axillary site as a last resort! Patient Assessment Mild hypothermia 96.8 F Increased blood pressure Increased muscle tone Start of shivering 95.0 F Maximum shivering Mild hypothermia 93.2 F Amnesia, poor judgment & maladaptive behaviors Painful joints Normal blood pressure Maximum respiratory response and then in heart rate Patient Assessment Mild hypothermia 91.4 F Apathy Ataxia & then in respiratory rate Cold diuresis Moderate hypothermia 89.6 F Stupor 25% in oxygen consumption 87.8 F Shivering stops 86.0 F Insulin looses effectiveness Arrhythmias begin to develop Patient Assessment Moderate hypothermia 85.2 F Progressive in: Level of consciousness Pulse Respirations Pupils dilated Paradoxical undressing Patient Assessment Severe hypothermia 82.4 F Decreased threshold for VF O 2 consumption by 50% Pulse by 50% Significant hypoventilation Patient Assessment Severe hypothermia 80.6 F Significant loss of reflexes and voluntary motion 78.8 F Loss of reflexes and response to pain Severe hypothermia 77.0 F Cerebral blood flow 33% normal Cardiac output 45% normal Pulmonary edema may develop 75.2 F - Significant hypotension & bradycardia 5

6 Patient Assessment Severe hypothermia 74.3 F No corneal reflexes 71.6 F Maximum risk of ventricular fibrillation Oxygen consumption by 75% Profound hypothermia 68.0 F Pulse 20% of normal 66.2 F Brain wave activity ceases 66.4 F - Asystole THEY AIN T DEAD UNTIL THEY ARE WARM AND DEAD! Pre-hospital Treatment Prevent further heat loss Remove from cold environment Remove wet and/or restrictive clothing If available, add wrapped heat sources to groin, neck, axilla Begin passive re-warming Wrap in layers Start with polymer sheets Add blankets/sleeping bags Cover head!!! Keep hands at sides Avoid radiant heat Pre-hospital Treatment Body to body rewarming is of no practical value. (Danzl, 2001, p. 504) Pre-hospital Treatment If conscious with adequate airway, give warmed, sweet beverages Keep in horizontal position Handle gently Prevent excess movement Establish IV/IO access Fluid challenge with D5%NS Any dextrose IV fluid Avoid LR d/t lactate Place IV bag under patient Wrap IV tubing in chemical warmer Pre-hospital Treatment Avoid massage of limbs Attach cardiac monitor Increase gain May have to use benzoin Small gauge needles through electrodes may be needed Life support issues Intubate (ET or Combitube) Avoid cuff overinflation Ventilate with 100% oxygen Warmed & humidified, if available Heat/moisture exchanger (HME) to prevent further heat losses 6

7 Pre-hospital Treatment Life support issues Assess pulses for > 1 minute If no pulse or signs of circulation, begin CPR Defibrillate up to three times for: Pulseless ventricular tachycardia Ventricular fibrillation Withhold further defibrillations Life support issues Continue CPR Withhold medications Transport to definitive care ASAP! Continue passive re-warming Consider arterial line Avoid pulmonary artery or CVP catheter into subclavian Draw labs X-rays for any trauma Insert an NG tube Insert foley catheter Begin IV therapy Use fluid warmer to deliver IVs Fluid challenge with D5%NS Any dextrose IV fluid Avoid LR d/t lactate Monitor for: Compartment syndrome Rhabdomyolysis Life support issues Intubate (ET or Combitube) Avoid cuff overinflation Ventilate with 100% oxygen Warmed & humidified, if available Heat/moisture exchanger (HME) to prevent further heat losses 7

8 Life support issues Assess pulses for > 1 minute If no pulse or signs of circulation, begin CPR Defibrillate ONE TIME for: Pulseless ventricular tachycardia Ventricular fibrillation Withhold further defibrillations until core temperature > 86 F Life support issues Continue CPR Medications Hold until core temps > 86.0 F Administer 2 3 X normal intervals Consider thiamine if alcohol related Active re-warming required in core temps < 89.6 F Active external re-warming TRUNCAL area only! Forced, heated air Wrapped, hot packs to groin, neck, axilla Immersion not practical Active internal re-warming Use as many modes as possible for best effect Airway re-warming Heated, humidified oxygen Prevents further heat loss Heated IV infusions One L can core temp by 1.4 F Tubing can loose a lot of heat Will likely need significant volume to correct cold diuresis Naso-gastric irrigation Monitor ins and outs to assure fluid balance Intubate to maintain airway ml boluses of electrolyte solution (NS, LR) Allow 15 minute dwell Closed thoracic lavage Two tube method Anterior/posterior tubes placed Fluid instilled anterior Drained posterior After re-warming, DC anterior tube and maintain posterior tube to drainage system 8

9 Closed thoracic lavage Single tube method Single tube placed poster, with Y connector ml boluses of electrolyte solution (NS, LR) Allowed 15 minute dwell Fluid suctioned out Peritoneal lavage Large bore catheter inserted Empty bladder and stomach Up to 2 L electrolyte solution (NS, LR) instilled Allowed 20 minute dwell & then siphoned out Aggressive internal re-warming VERY effective!!! Usually only available at higher level trauma centers Multiple types Electrolyte disturbances primarily potassium Bacterial infection Alterations in immune system Primarily pneumonia, but other sites possible Significantly affected by extremes of age Complications Coagulation disturbances primarily loss and/or malfunction of platelets Possibility of local cold injuries and/or other trauma 9

10 Non-Freezing Injuries One Two Three Four Usually caused by cold and wet conditions Risk factors, same as with hypothermia Additional risk factors may make patient more vulnerable Additional risk factors Diabetes Tight, constriction clothing Tobacco use Dehydration Previous local cold injury Vascular insufficiency/disease Chilblain - Pernio Same basic cause prolonged exposure to wet and cold Chilblain = 3 12 hour exposure Pernio More than 12 hours exposure or Repeated, frequent exposure Chilblain 3 12 hour exposure Swelling & tenderness that resolves with drying May display blisters Pain with > 6 hours exposure May have deep sensitivity to foot pressure for several days Treatment Dry Gentle massage Pernio Extension of chilblain > 12 hour or repeated, frequent exposure Deep pain that persists for multiple days Partial thickness blisters Swelling Treatment Dry Elevation to help swelling NSAID such as ibuprofen Significant pain control issues Pernio Sequela Long term sensitivity to even mild cooling of limb Pain Numbness Paresthesia 10

11 Trench Foot Also known as immersion foot Prolonged exposure to: Cold Wet Tight constricting boots Reduced blood flow caused by: Vasoconstriction, leading to Tissue hypoxia and Cellular death Injuries compounded by walking on injured feet Trench Foot Symptoms appear in three phases Pre-hyperemic phase Extremity blanched & cold Patient reports cold and numb feet Balance is impaired Trench Foot Hyperemic phase Last 6 10 weeks Upon warming, feet become: Red Hot Painful Swollen Hyperemic phase 7 10 days after injury: Pain intensifies Loss of motor control & sensation Pain & numbness with warming or dependency of foot Trench Foot Hyperemic phase 7 10 days after injury: Blisters form (bloody = bad!) Black eschars form Nails slough without pain Tissue mummifies Gangrene may require premature surgery 11

12 Trench Foot Post-hyperemic phase Swelling, pain & numbness Cold sensitivity Neurological damage will affect balance and mobility Treatment Dry & elevate feet to heart level Pain control issues significant Minor injuries can produce significant problems in later life = Cold sensitivity Frostbite Damage occurs in four phases Pre-freeze phase tissue cools Freeze-thaw phase ice crystals from in tissue Freeze-thaw phase Extra cellular ice crystals Caused by slow cooling Cellular dehydration Intra-cellular electrolyte concentration Break down of cellular walls Frostbite Freeze-thaw phase Intra-cellular ice crystals Caused by fast cooling Breakdown of cell walls Breakdown of cell proteins Cells rupture Vascular stasis phase Plasma leaks into tissue Emboli showers to small blood vessels Late ischemic phase Thrombosis formation Ischemia Tissue death Frostbite Initial classification VERY difficult Superficial frost bite First degree Numbness White, firm plaque at site Edema forms on re-warming 1 st Degree Frostbite of Ear 12

13 Frostbite Superficial frostbite Second degree As with First degree Blisters filled with clear fluid Deep frostbite Third degree As with Second degree Blisters filled with bloody fluid 4 & 5 Weeks After Frostbite Frostbite Deep frostbite Fourth degree Full thickness damage Tissue may appear mummified 24 Hours after Frostbite 6 Weeks Later 13

14 Frostbite Initial or presenting symptoms Numbness with SIGNFICANT pain on re-warming Tissue changes as described above Tissue may appear mottled blue or frozen Symptoms on re-warming Redness Sensation returns until blisters form Sensory loss persistent Blisters form within 6 24 hours Frostbite Edema forms within 3 hours and may last 5 days Pain EXTREME on re-warming Becomes throbbing May have burning sensation Electric current-like shock Eschars of black tissue form in 9 15 days Mummification and lines of demarcation form in days Frostbite Prognostic signs Favorable Sensation to pinprick Normal color and warmth Large, clear blisters Appear early Extend to tips of digits Prognostic signs Unfavorable Small, dark blisters Appear late Do NOT extend to tips of digits Absence of edema Cyanosis that does not blanch Frostbite All but the most minor frostbite cases should be admitted to the hospital. (McCauley, p. 187) Pre- Assess and treat: Hypothermia Dehydration Trauma Handle gently!! If < 2 hours from definitive care, do NOT re-warm Remove wet/restrictive clothing Keep away from dry heat sources (fires, car heaters) Pad and splint extremity Leave blisters intact Elevate to level of heart Pre- Prohibit use of: Tobacco Alcohol Provide rapid transport to definitive care If > 2 hours from definitive care: Rapid re-warming with water After re-warming, treat as above DO NOT ALLOW INJURY TO BE RE-EXPOSED TO COLD!!! 14

15 Pre- Rapid re-warming in water 104 to 108 F for 30 minutes Continue until tissue becomes pliable and red Active motion helpful Massage contraindicated!!!! Favorable signs on re-warming Rapid return of skin warmth and sensation Redness Unfavorable signs on re-warming Skin that continues to be: Pale Cold Numb Blister management AVOID betadine White blisters Represents superficial injury Debride to remove inflammatory mediators Aloe vera ointment every 6 hours Blister management Red blisters Sub-dermal injury Aspirate fluid Leave blisters intact to prevent conversion to full-thickness Aloe vera ointment every 6 hours Medications Ibuprofen, 400 mg Q12 hours Tetanus anti-toxin, if needed Penicillin Pentoxifylline blood viscosity RBC flexibility Pain control Morphine drip or PCA Fentanyl drip or PCA Avoid Demerol may cause neurological complications Long term therapy Physical therapy maintains mobility Occupational therapy maintains functional ability Long term therapy Surgical intervention usually held until: Tissue declares viability may take months Tissue infection Amputation for Gangrene 15

16 Complications VERY sensitive to cold re-injury during recovery Long term sensitivity to cold & cold injuries for life Changes in skin color Joint stiffness & pain on movement Sacred Heart Medical Center and Children s Hospital Michael W. Day, RN, MSN, CCRN Daymw@shmc.org Fax Materials to: Renee Anderson (fax) (d) andersr@inhs.org 16