Environmental Emergencies Flashcards
Environment
All of the surrounding external factors that affect the development and functioning of a living organism
Thermogenesis
Production of heat and energy for the body and main method of dealing with cold stressors
Vasoconstriction and shivering
Thermolysis
Release of stored heat and energy, and body’s main reaction to heat
Vasodilation and sweating
Main mechanisms are radiation, conduction, convection, evaporation
Thermoreceptors
- Peripheral - skin and certain mucous membranes that mostly respond to cold
- Central - deep tissues, spinal cord, abdominal viscera, and great veins that mostly respond to cold
Basal metabolic rate (BMR)
Energy at which the body consumes energy just to maintain stability
Core temperature reflects internal energy production and consumption
Hypothermia
Low core temperature attributed to:
- Inadequate thermogenesis
- Excessive cold stress
- A combination of both
Pathophysiology of hypothermia
Compensation = shivering, vasoconstriction, increased BMR
Decompensation = decreased cardiac output, increased viscosity of hemoglobin (viscosity increases 2% for every centigrade decrease)
Affects of alcohol on heat loss in urban setting
- Impairs shivering thermogenesis
- Promotes cutaneous vasodilation
- Liver disease create inadequate glycogen stores and poor nutrition
- Impair judgment
Degrees of hypothermia
Mild = core temperature > 32 with symptoms
- Shivering, lethargic, stiff/uncoordinated muscles
Severe = core temperature < 32 with symptoms
- No shivering, disoriented to confused, rigid/stiff muscles, dysrhythmias, increased risk of vfib <30 degrees
Compensated = normal core temperature with symptoms
Rewarding shock
Reflex vasodilation that causes cold/acidic blood from the periphery to return to the core
Afterdrop - further decreased core body temperature
Frostbite
Environmentally induced freezing of body tissues
Ice crystals form and water is drawn out of cells; the crystals expand causing destruction of the cells, and damage to the blood vessels causes loss of vascular integrity
Tissue swelling and loss of nutritional flow
Types of frostbite
- Superficial - freezing of epidural tissue, redness followed by blanching and diminished sensation
Altered sensation, white/waxy skin, skin firm on palpation but underlying tissue is soft, appears cyanotic upon thawing, capillary leakage causing edema in area - Deep - freezing of epidural and subcutaneous layers with a white frozen appearance
White/white-yellow/blue mottled skin, hard and cold with no sensation, major tissue damage from thawing, turns purple as it thaws and causes excruciating pain, potential for gangrene
Hyperthermia
Unusually high core body temperature
Heat cramps
Muscle cramps caused by overexertion and dehydration, and due to sodium loss from sweating
Slightly elevated body temperature, skin moist and warm
Remove from environment and give oral saline solution
Heat exhaustion
Mild heat illness caused by dehydration and sodium loss
- decreased circulating blood volume, venous pooling, reduced CO output
Increased body temperature, cool clammy skin, heavy perspiration, diarrhea, N/V, muscle cramps, headache, CNS changes, tachypnea, rhabdomyolysis
Place supine, remove from environment, saline, cool patient, treat for shock
Heat stroke
Least common but most deadly heat illness caused by a severe disturbance in the body’s thermoregulation; core temp > 40
Incoherent hx, irritability, combativeness, hallucinations, possible stroke like symptoms, hot skin with no sweating, deep/shallow respirations, rapid pulse, hypotension, confusion, disorientation, possible unconsciousness, seizures
Active cooling, oxygen, fluids, cardiac monitoring, avoid vasodepressors/anticholinergics
Affect of dehydration
Inhibits vasodilation and thermolysis
Orthostatic hypotension, decreased urine output, skin turger, signs of hypovolemic shock
Fever
Pyrexia- elevation of body temperature above normal
Pathogens enter body and stimulate production of pyrogens (release of prostaglandin E2), resetting hypothalamic thermostat
Boyle’s Law
At a constant temperature, the volume of gas is inversely proportional to its pressure
Increased pressure = decreased volume and vice versa
Dalton’s Law
Each gas in mixture exerts the same partial pressure that it would exert if it were alone in the same volume and that the total pressure of a mixture of gases is the sum of the partial pressure of all gases in the mixture
Henry’s Law
The amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas above liquid
Barotrauma (the squeeze)
Pressure imbalance between gas filled spaces inside the body and external atmosphere (eg., inability to equalize)
Compression of gases with the body spaces on descent, or expansion of gases on ascent
Use valsalva maneuver to equalize
Nitrogen narcosis
Altered mental status caused by breathing compressed air at depth; nitrogen dilutes concentration of oxygen
Euphoria, inappropriate behaviour, lack of safety concern, tingling of lips, gums, legs
Arterial gas embolism (AGE)
Air bubbles from ruptured alveoli enter pulmonary capillaries, then into cardiac circulation (cardiac arrest) or cerebral circulation
ALOC, paralysis, seizures, chest pain, dyspnea, sudden death
Decompression sickness
Nitrogen bubbles interfere with tissue perfusion and trigger chemical changes in the body
CNS and spinal cord most affected
Acute mountain sickness (AMS)
Three criteria: recent gain in altitude, several hours at new altitude, and headache with on of:
- Fatigue/weakness
- GI symptoms
- Dizziness/lightheadedness
- Difficulty sleeping
HA usually throbbing and worse in temporal and occipital areas made worse by valsalva maneuver
High altitude pulmonary edema (HAPE)
At least two of:
- Dyspnea at rest
- Cough
- Weakness
- Decreased exercise performance
- Chest tightness/congestion
AND at least two of:
- Central cyanosis
- Audible rales/wheezing in at least one lung field
- Tachypnea
- Tachycardia
High altitude cerebral edema (HACE)
Change in mental status and/or ataxia in a person with AMS
OR
Change in mental status AND ataxia in person with AMS
Acetazolamide (Diamox) for prevention/treatment
