Acute Care Medicine - Heat and Cold Exposures

Question 1

Differentiate between heat exhaustion and heat stroke

Answer 1

Body Temperature
- 38.3 to 40C in exhaustion
- >40C for stroke
Thermoregulation
- body able to cool itself when removed from heat with rest in exhaustion
- body unable to cool itself and begins to overheat in stroke
CNS function
- No dysfunction in exhaustion
- seizure, altered LOC, and delirium in stroke

Question 2

Discuss the diagnostic criteria and common symptoms of heat stroke

Answer 2

Criteria
- Body temperature >40
- CNS dysfunction
- Exposure to severe environmental heat
Symptoms
- muscle cramps
- hypovolemic
- syncope
- headache
- palpitation
- oliguria

Question 3

Discuss common investigations for heat stroke

Answer 3

• CBC may show leukocytosis
• renal function for acute renal failure with high BUN and creatinine
• liver function
• CK for rhabdomyolysis
• ECG

Question 4

Discuss the management for heat stroke

Answer 4

Stabilize
- ABC
- consider central venous pressure to assess volume status (want between 8-12mmHg)
- require 250-500mL bolus of NS
Cooling
- continuous temperature monitoring through rectum or esophagus
- target core of 38-39
- lie patient naked and spray with lukewarm water while fan is blowing them
- Lorazapam 1-2mg IV to inhibit shivering and agitation
- Other cooling
- immersion is ice water
- water ice therapy
- ice packs to axilla, neck and groin
- peritoneal lavage
- cool blankets and cool IV fluids (22C)
- no need for anti-pyretics

Question 5

Discuss the criteria of hypothermia and pathophysiology

Answer 5

Criteria
- Body temperature <35C with multisystemic features
- Mild 32-35
- Moderate 28-35
- Severe <28
Pathophysiology
- hypothalamus cause shivering and increase thyroid, adrenal, and sympathetic activity leading to peripheral vasoconstriction, hypertension, tachycardia, ileus and bladder atony
- cold damages cells and crystallizes water disrupting electrolyte concentrations
- vasoconstriction lead to blood stasis and increase risk for VTE
- cold also inhibits coagulation
- vasoconstriciton lead to tissue necrosis
- thawing cause marked edema due to melting water crystals and cellular damage

Question 6

Discuss the systemic features associated with hypothermia

Answer 6

Thermoregulation
- mild have shivering intact
- moderate and severe has loss of shivering and rapid cooling
Hematologic
- Moderate increase hematocrit, thrombocytopenia, leukopenia and hypercoaguable
- severe have DIC and bleeding
Neurologic
- Mild have disorientation, ataxia, dysarthria and hyper-reflexia
- moderate have hallucinations, dilated pupils and hyporeflexia
- severe have coma, absent pupillary response
Respiratory
- Mild have tachypnea and bronchorrhea
- moderate have hypoventilation, respiratory acidosis, hypoxemia, atelectasis
- severe have apnea, pulmonary edema and respiratory distress
Cardiovascular
- Mild have tachycardia and hypertension
- Moderate have bradycardia, hypotension, and prolonged QTc and J waves
- Severe have heart block, atrial fibrillation, VF
GI
- Moderate and severe have pancreatitis, gastric ulcer and hepatic dysfunction
MSK
- hypertonia -> rigidity -> rhabdomyolysis

Question 7

Discuss investigations for hypotheramia

Answer 7

Every 4hrs

• CBC
• electrolytes
• Blood glucose
• lactacte
• LFT
• lipase
• Creatinine and BUN
• CK
• PTT, INR, fibronogen

Question 8

Discuss the technique for re-warming

Answer 8

Passive External Rewarming
- for mild hypothermia warming at 0.5-2C per hour
- blankets
Active External Rewarming
- for mild hypothermia without shivering or moderate
- 2C per hour
- heating blankets
- heated force air systems
- heated pads
- radiant heat
- warm baths (45C)
Active Internal Rewarming - Simple
- moderate hypothermia
- 1-2C per hour
- warmed IV fluids and warmed oxygen
Active Internal Rewarming - Invasive
- Moderate with cardiovascular compromise or severe
- 1-4C per hour
- Peritoneal irrigation
- Pleural irrigation
- Esophageal warming tubes
- Endovascular rewarming
Extra-Corporeal
- Severe, renal failure/hyperkalemia, cardiac arrest
- 2-3C per hour up to 9.5C per hour
- AV or VV rewarming
- Heated hemodialysis
- Cardiopulmonary bypass

Question 9

Discuss the classification of frost bites

Answer 9

• Applied after rewarming
  1st Degree
• superficial, characterized by central area of pallor and anesthesia of skin surrounded by erythema
  2nd Degree
• no tissue loss
• large blisters containing clear fluid surrounded by edema and erythema developed with 24hrs
  3rd Degree
• deeper injury
• proximal smaller and hemorrhagic blisters
• skin form black eschar in >1 week
  4th Degree
• Injury into muscle and bone
• complete tissue necrosis and mummification in 4-10d
• auto-amputation

Question 10

Discuss the signs of frostbite

Answer 10

• cold, numbness and clumsiness of area

- skin can be insensate, white/grayish yellow, hard and waxy

Question 11

Discuss the management of frost bite

Answer 11

Pre-Hospital
- remove non-adherent wet clothing
- get patient to warm environment
- pad or splint to prevent mechanical trauma
- place in warm water or use body heat
- No rubbing
Hospital
- Tetanus prophylaxis
- Rapid re-warming in whirlpool bath (40-42) for 15-30 minutes
- if risk of amputation consider tPA plus intra-arterial heparin
- wound care
- NSAID
- aspirate hemorrhagic blisters
- Consider IV Abx against staph, strep and pseudomonas

Question 12

Discuss the features of a superficial burn

Answer 12

Involved tissue
- Epidermis
Appearance
- Dry, red
- blanches with pressure
Sensation
- Painful
Healing Time
- 3-6 days
Common Exposure
- UV exposure

Question 13

Discuss the features of a superficial/partial thickness burn

Answer 13

Involved tissue
- Epidermis and part of dermis
Appearance
- Blisters
- Blanches with pressure
- moist, red, weeping
Sensation
- Painful to temperature and ir
Healing Time
- 7-20 days
Common Exposure
- Scald

Question 14

Discuss the features of deep partial thickness burn

Answer 14

Involved tissue
- Epidermis and part of dermis
Appearance
- blisters that are easily unroofed
- wet or waxy
- does not blanch with pressure
Sensation
- perceptive of pressure only
Healing Time
- >21 days
Common Exposure
- Scald
- flame
- oil, grease

Question 15

Discuss the features of full thickness burns

Answer 15

Involved tissue
- epidermis and all of dermis
Appearance
- waxy white to leathery gray to charred and black
- dry and inelastic
- no blancing
Sensation
- only to deep pressure
Healing time
- Never heals if >2% of total surface area
Common Exposure
- scald
- flame
- steam
- oil, grease
- electrical

Question 16

Discuss the features of fourth degree burn

Answer 16

Involved Tissue
- Down to muscle and fascia
Appearance
- underlying tissue visualized
Sensation
- deep pressure only
Healing Time
- never heals
Common Exposure
- Same as full thickness

Question 17

Discuss the severity of burns

Answer 17

Minor
- <=15% of TBSA with <=2% full thickness
Moderate
- 15-25% TBSA with <=10% full thickness
Major
- >25% TBSA or >10% full thickness
- Burn that involve face/hands/feet/perineum

Question 18

Discuss the burn care

Answer 18

Immediate
- burned area should be cooled immediately using cool water or saline soaked gauze for 15-30 minutes
- watch for signs of hypothermia
Prevention of Infection
- Tetanus
- topical antibiotics Silver Sulfadiazine
Wound Management
- pain management with local or regional anesthesia
- clean and irrigate
- debride necrotic tissue
- dress with 1st layer being non-adherent mesh gauze, 2nd layer fluffed dry gauze and 3rd layer of elastic gauze