Flashcards in Enviro Emergencies Deck (55):
distribution of elect. injuries?
- young kids: oral contact w/ electric cords and outlets
- adults: construction and electrical workers (90% men)
Mech of elect. injury?
- direct effect of electrical current on body tissues: severity depends on voltage, duration, type, current path throughout body, enviro factors
- conversion of elect energy to thermal energy results in deep and superficial burns
- exit wound often larger than entrance site
- as current flows through body, greatest damage is sustained by nerves, blood vessels and muscle
Low voltage AV current injury vs high voltage AC and DC injury?
- low voltage AC: will cause muscle tetany, causing injured person to cont grasp source, increasing contact time, tend to cause V fib
- high voltage: cause single violent muscular contraction which tends to throw victim from source, increasing risk of blunt trauma, and blast injuries, tend to cause asystole and resp arrest
initial PE of electrical injury?
- primary, secondary surveys, ABCs, C spine immobilization
- IV 2 large bores, fluid repalcement: isotonic crystalloid
Neuro PE of electrical injury?
- CNS: neuro impairment occurs in 50% of high voltage injuries, transient LOC, agitation, confusion, coma
- visual disturbances: pupils may be fixed and dilated or asymmetric due to autonomic dysfxn, 50-80% of those struck by lightening have ruptured eardrums
- spinal cord injuries:
fxs, current itself (ascending paralysis, spinal cord syndromes, can be immediate, transient or delayed)
- peripheral nerves: injuries often involve hand touching power source
PE for cutaneous wounds for electrical injury?
- burns: entry and exit pts
- look for entrance and exit wounds and degree of burns
- burns can be cleansed and dressed w/ silver suflfadizine
- extremities need careful exam for neurovasc compromise, compartment syndrome
- oral burns:
kids who chew on wires, vasc injury to labial artery can occur, responsible parents can do home monitoring
Bone PE in electrical injury?
- bone has highest resistance of any body tissue, generates greatest amt of heat when exposed to electrical current
- areas of greatest destruction are often deep tissue surrounding long bones
- deep electro-thermal tissue injury can result in edme and the development of compartment syndrome
Renal PE of electrical injury?
- rhabdo can occur and be complicated by pigment induced renal failure
- hypovolemia due to extravascular extravasation of fluid can lead to prerenal azotemia and acute tubular necrosis
Tx of electrical injury? labs?
- trauma: ABCs, c spine
- aggressive fluid replacement: isotonic crystalloid fluids, acute hypotension should prompt search for thoracic or intra-abd bleeding secondray to blunt trauma
- labs - lytes, BUN/Cr, CK, serum and urine myoglobin, CBC, EKG
- watch lytes
- wound care
- myoglobinurea: can cause renal failure, amputation may be necessary
- tetanus prophylaxis
- tx seizures
- consult to general surgeon
- kids w/ oral injuries: ENT
- preg women: OB
Monitoring electrical burns?
- continuous CV monitoring: arrhythmias occur 15% of time after injury
- needs to be monitored for development of compartment syndrome
- I and O followed, maintain output more than 100 mL/hr as goal, monitor for rhabdo, and renal failure
PP of lightning strikes?
- DC current
- can result in:
step potential (cow is worse off than you)
- extensive tissue damage and renal failure are rare
- immed cardiac arrest result from direct current depolarization of myocardium and can result in systole
- resp arrest from depolarization and paralysis of medullary resp center
Minor injuries resulting from lightning strikes?
- stunned pt
- confusion, amnesia
- short term memory problems
- muscle pain
- temporary visual or auditory problems
- most minor injuries have gradual improvement, no long term sequelae
What would alert you that the pt sustained a lightning injury?
- pt found unconscious or in arrest outside during weather conditions
- pupil dilation or aniscoria may occur
- ruptured tympanic memrbanes or fern like erythematous skin marking
Tx of lightning strike injury?
- aggressive resuscitation
- ACLS, CPR
- cardiac monitoring, SAO2, BP
- 2 large bore IVs
- high flow O2
- secondary survey for occult injuries:
- moderate to severe injuries: admite to critical care unit
- minor: admit, closely monitor cardiac and neuro status
How common is drowning in US?
- 3rd MC cause of accidental death in US
- 2nd MC in those younger than 45
- leading cause of death in kids under 5 in states where pools and beaches are more accessible
RFs for near drowning?
- inability to swim or overestimation of swimming capabilities
- risk taking behavior
- use of EToH or drugs
- inadequate adult supervision
- hypothermia which can lead to rapid exhaustion or cardiac arrhythmias
- concomitant trauma, CVA or MI
- hyperventilation prior to shallow dive
PP of drowning?
- after submersion degree of pulm and in particular CNS insult determine ultimate outcome
- drowning begins w/ period of panic:
loss of normal breathing pattern, breath holding, air hunger and struggle to stay above water
- reflex inspiratory efforts occur:
leading to hypoxemia by:
aspiration, reflex laryngospasm
Diff b/t dry drowning and wet drowning?
- dry: 10-20% of submersion injuries, caused by laryngospasm, followed by hypoxia and LOC
- wet: aspiration of water, dilution and washout of pulmonary surfactant
- diminished gas transfer
- ventilation-perfusion mismatch
Diff b/t fresh water and salt water drowning?
transient hemodilution, causing blood cells to swell and burst. If large enough vol are aspirated, sig hemolysis is possible
- salt water:
lungs fill w/ salt water which draws blood out of bloodstream and into lungs, build up of Na+ in alveoli stops O2 from reaching blood
End organ effects of drowning?
- pulm: fluid aspiration, both salf and fresh water: wash out surfactant, producing noncardiogenic edema and ARDS -S/S: SOB, rales, wheezing
- neuro: hypoxemia, ischemia cause neuronal damage, can produce cerebral edema and elevated ICP, 20% near drowning victims sustain neuro damage limiting fxnl recovery
- CV: arrhythmias 2nd to hypothermia and hypoxemia, sinus brady and fib more common
- acid-base and lytes: metabolic and/or resp acidosis often occurs, sig lyte imbalances don't generally occur except those submerged in unusual media: dead sea
Prehosp care of drowning victim?
- asses need for CPR (Pulses may be weak)
- support neck in neutral position
- heimlich manuever or other postural drainage techniques dont help - DON'T delay rescue breathing
- hypothermic pts should be rewarmed
Management of drowning victim in ER?
- continue resuscitative efforts
- head and spinal cord injuries should be sought (precip pre near drowning)
- re-warming: blankets, bair hugger, overhead warmers, continue resuscitation unitl pt is at 32-35 C (90-95 F)
- pts w/ GCS 13 or greater: O2, observation for 4-6 hrs, if pulm exam and room air O2 remain normal - d/c, if not better reassess and admit
- GCS less than 13: O2, CXR, labs: ABGs, CBC, CMP, could develop dilutional hyponatremia and have seizures
- PT/PTT UA, CK urine myoglobin, urine drug screen
Management of near drowning victim as inpt?
- neuro: major determinants of neuro outcome are:
duration of LOC, neuro state of pt at presentation, goal of management: prevent secondary injury: cerebral edema, hypoxemia, fluid and lytes imbalances, acidosis, seizure activity
- pulm: may need intubation w/ PEEP (ARDS), CXRs should only be done if indicated, bronchospasm is often seen and responds to beta agonists, glucocorticoids or prophylactic abx aren't helpful
What are factors assoc w/ a poor prognosis w/ near drowning victim?
- under for more than 10 min
- time to effective BLS: more than 10 min
- resuscitation over 25 min
- hypothermia w/ core temp (less than 33 C or 92F)
- GCS of 5 (comatose)
- younger than 3 yo
- persistent apnea and reqr of CPR in ER
- arterial blood pH less than 7.1
- water temp more than 10C (50F)
- core temp less than 35C (95F)
- mild: core temp 90-95F
- mod: 82-90F
- severe: less than 82F
- while mostly seen in cold climates, can develop w/o exposure to extreme enviro conditions
What groups are at greatest risk for hypothermia?
- elderly: lose their ability to sense cold
- neonates: large surface to vol ratio
- both groups have limited ability to increase heat production and conserve body heat
- individuals w/ alt sensorium
PP of hypothermia?
- heat is generated by cellular metabolism (heart and liver)
- loss by skin and lungs:
- heat is preserved by:
periph vasoconstricition, shivering, non-shivering thermogenesis: increase in metabolic rate from thyroid and adrenal glands
Presentation of mild hypothermia?
- tachypnea, tachycardia, hyperventilation
- ataxia, dysarthria, impaired judgement
- shivering and cold diuresis
Presentation of mod. hypothermia?
- reductions in pulse rate and CO: hypoventilation - a fib, jxnl bradycardia can occur
- CNS depression, hyporeflexia
- decreased renal blood flow and loss of shivering
- paradoxical undressing
Presentation of severe hypothermia?
- pulmonary edema
- hypotension, bradycardia, ventricular arrhythmias, asystole
Dx of hypothermia?
- must use low reading thermometer
- labs to ID potential complications:
EKG: elevation of J pt: J or osborne wave
Management of hypothermia?
- initiation of rewarming:
*passive external and *active external: combo of blankets, radiant heat, warm baths or forced warm air, risk is core temp afterdrop - occurs when trunk and extremities are warmed simult - so warm trunk 1st and minimize use of periph muscles
*active internal rewarming: can be used alone or w/ active external rewarming, pleural and peritoneal irrigation w/ warm saline, hemodialysis and cardiopulm bypass, warm humidified O2, warm IV fluids and bladder or GI irrigation w/ warm saline
Tx arrhythmias in hypothermia?
- hypothermic heart is very sensitive to movement and rough handling of pt may precipitate arrhythmias
- A fib and flutter usually resolve w/ rewarming
- management of V fib and asystole can be difficult - they may be refractory to therapy until pt has been rewarmed (core temp 86-90F)
PP of frostbite?
- freezing of tissue: disease of morbidity not mortality
tissue destruction due to:
- immed cold induced cell death
- more gradual development of localized inflammation and tissue ischemia - made worse in setting of thawing followed by refreezing
Classification of frostbite?
-1st degree: central area of pallor and anesthesia of skin surrounded by edema (superficial)
- 2nd: blisters form containing clear or milky fluid surrounded by edema/erythema w/in 24 hrs (superficial)
- 3rd: injury deeper than 2nd degree, blisters are hemorrhagic, progressing to black eschar over several weeks (deep)
- 4th: extends to muscle and bone, involves complete tissue necrosis (deep)
Simpler classification of frost bite?
- superficial corresponds to 1 and 2nd degree
- deep: 3-4th degree
Presentation of frostbite?
- pt c/o numbness, clumsiness of affected area
- skin may be insensate, white or grayish yellow in color and hard or waxy to touch
- bullae may be present
- cases of delayed presentation eschars or sign of tissue necrosis may be present
Dx of frostbite?
- made clinically
- dx studies helpful to determine existence of comorbidities and extent of injury:
Technetium-99 scintography used to predict long term viability of affected tissue
- goal is to allow earlier debridement or amputation of dead or dying areas while leaving viable tissue intact
Prehosp tx of frostbite?
- remove wet clothes
- avoid walking on frostbitten feet
- don't rewarm if there is possibility of refreezing
- don't rub frostbitten areas
- avoid use of stoves or fires to rewarm
What prog factors should you determine w/ frostbite?
- temp and wind velocity
- how long was extremity frozen
- if thawed, did refreezing occur
- was there any self tx: rubbing w/ aloe vera cream or ibuprofen
- recreational drugs or alcohol involved
- any predisposing medical conditions
Tx in hosp of frostbite?
- rapid rewarming:
waterbath heated to 40-42 C
- dry heat diff to regulate
- thawing usually completed in 15-30 min
- application of dressing, elevation, splinting
- tetanus proph
- topical aloe and ibuprofen
- in pts at high risk for life alt amputation: tPA
- surgical consultation: may reqr long term wound care, daily hydrotherapy, repeatd tissue debridement, escharotomy and poss delayed amputation
Managing blisters in frostbite pts?
- drain, debride, bandage large nonhemorrhagic bullae that interfere w/ movement
- hemorrhagic bullae of comparable size and location are drained by aspiration, but not debrided
- minor bullae should be left intact
Complications of frost bite?
- short term: infection, gangrene, autoamputation
- long term: hypersensitivity to cold w/ increased risk for developing frostbite again, chronic parasthesias, decreased sensation to touch when hands are involved
2 types of heat exhaustion?
- water depletion: inadequate fluid replacement by individuals working in hot enviro - can progress to heat stroke (hypovolemia)
- salt depletion: large volumes of thermal sweat are replaced w/ water w/ too little salt: hyponatremia, hypochloremia
- most cases are mixed
S/S of heat exhaustion?
- reflects sig vol depletion
- non-specific sxs:
weakness, malaise, fatigue, HA, lightheadedness, dizzines, N/V
- clinical manifestations: hypotension, tachycardia, tachypnea, diaphoresis, syncope
Tx of heat exhaustion?
- cool enviro
- vol and lyte replacement
- mild cases: oral replacement
- moderate cases: 1-2 L of NS, guided by serum lytes
What is heat stroke?
- life threatening emergency that occurs when homeostatic thermoregulatory mechanisms fair
- elevation of body temp over 40.5C (105F)
- w/ elevation of temp, cell damage occurs: tissue damage is affected by:
PP of heat stroke?
- CNS dysfxn w/ occurrence of cerebral edema is common:
ataxia, irritability, confusion, bizarre behavior, combativeness
- greatly increases skin blood flow: fxnl hypovolemia compensated by vasoconstriction of splanchnic and renal vasculature
- if severe heat stress cont: splanchnic vasoconstriction will fail, heated blood increases ICP, decreases mean arterial pressure
Dx of heatstroke?
- exposure to heat stress, endogenous or exogenous
- signs of severe CNS dysfxn
- core temp usually above 104.9F (40.5C)
- dry, hot skin, but sweating may persist
- marked elevation of liver transaminases
How can heatstroke kill?
- about 10% of cases are fatal
- vascular sock: reduces blood flow to brain, leads to nervous system malfxn
- irregular pulse: arrhythmia - Heart atatck
- kidney failure
- blood clots start to form affecting vessels throughout body
Tx of heatstroke?
- ABCs: O2, cardiac monitoring, pulse Ox
- primary survey
- cooling is immediate goal: once pt arrives at hop - clothes should be removed nad rectal thermostat probe inserted for cont temp monitoring
- cooling tech:
cold water immersion
ice packing: neck, groin, axillae
cold gastric lavage: NG tube
cold peritoneal lavage : also used in some cases of AMI and ischemic CVA to mitigate myocardial and cerebral tissue damage
What is evaporative cooling?
- positioning fans close to completely undressed pt then spraying them w/ water
shivering, inability of cardiac electrodes to adhere to skin
What is immersion cooling?
place undressed pt in tub of ice water deep enough to cover trunk and extremities
WHen should cooling efforts be d/c?
- when rectal temp reaches 40C (104F)
- continued cooling below this may lead to hypothermia