Environmental Flashcards
Four mechanisms of heat transfer
Conduction: direct physical contact
Convection: heat loss to air and water vapour
Radiation: heat transfer by electromagnetic waves
Evaporation: conversion of liquid to gaseous phase
What 3 distinct functions regulate body temperature
Thermosensors: located peripherally and centeally; skin and in periodic anterior hypothalamus
Central integrative area: CNS creates set point
Thermoregulatory effectors: sweating and peripheral vasodilation
What are predisposing factors for classic heat stroke
Advanced age Psychiatric conditions Chronic disease Obesity Certain medications
Dehydration (vomiting, diarrhea, diuretics)
Drugs (anticholinergics), skin disease, occlusive clothing
Increased heat production: exercise, drugs (synpathpmimetics), fever, delirium, thyroid storm, MH, NMS, seizures
Cardiac disease, BB drugs
Hypothalamic hemorrhage
Atherosclerosis, diabetes
What percentage body weight loss represents moderately severe deficit
5-6%
What percentage body weight loss represents severe water depletion
7% or more
What is prickly heat
Acute inflammatory disorder of skin that occurs in tropical climates due to blockage of sweat gland pores by macerated stratum Cornell and secondary staphylococcal infection - aka miliaria, lichen tropicus, heat rash
Clinical presentation of prickly heat
Prurituc vesicles on erythematous base confined to clothed areas, area often anhidrotic
Ddx of prickly heat
Contact dermatitis
Cellulitis
Allergic reaction
Treatment of prickly heat
Chlorhexidine in a light cream or lotion
Salicylic 1% acid can be applied to localized areas to assist in discrimination but not use in children or large areas due to risk of salicylate intoxication
Aretha Myson can use for diffuse for posture the rest of us
What are heat cramps
Brief intermittent and often severe muscle cramps occurring and muscles fatigue by heavy work
Risk factors for heat cramps
He cramps typically caused by salt deficiency in person to produce large amount of thermal sweat and drink copious amounts of hypertonic fluid
Often occur after exercise and while relaxing
Occupations often affected our athletes roofers steel workers coal miners field workers and boil operators
Ddx for heat cramps
Hyperventilation tetany can be distinguished by the presence of carpopedal spasm’s and paraesthesias in the distal extremities and Perioral areas
Essentials of diagnosis of heat cramps
Cramps of most worked muscles Usually occur after exertion Heavy sweating during exertion Copiius hypertonic fluid replacement Hyperventilation not present and cool environment
Investigations for heat cramps
Lytes
They often have hyponatremia, hypochloremia
Treatment of heat cramps
Mild cases without dehydration treated or early with 0.1% or 0.2% salt solution or one quarter to one half teaspoon of salt all dissolved in 1 quart of water
Severe cases respond rapidly to IV NS
What is heat edema
Hydrostatic pressure and vasodilation of cutaneous vessels in heat resulting in accumulation of interstitial fluid in Lower extremities
Ddx of heat edema
CHF, liver disease states,lower extremity infections, DVT
What is heat syncope
Loss of consciousness and presence of heat exposure due to cutaneous vasodilation
What are the two types of heat exhaustion
Water depletion heat exhaustion and salt depletion heat exhaustion
Water caused by too little replacement
Salt caused by replacement of hypotonic fluid
Diagnosis of heat exhaustion
Symptoms of vague malaise fatigue and headache
Core temperature often normal and if elevated is under 40°C
Mental function essentially intact no coma or seizures
Tachycardia orthostatic hypotension and clinical dehydration may occur
Other major illness ruled out
If in doubt treat as heat stroke
Investigations in patient with heat exhaustion
Electrolytes: hyponatremia, hypochloremia, and the low urinary sodium and chloride concentrations
CPK in renal function, hepatic transaminases
Management of heat exhaustion
Rest
Cool environment
Assessment of volume status
Fluid replacement: normal Celine to replete volume if patient is orthostatic, replace slowly to avoid cerebral edema
Healthy young patients are treated as Outpatients
Consider admission efficient is older, has significant electrolyte abnormalities or would be at risk for recurrence if discharged
What is the difference between heat exhaustion and heatstroke
Homeostatic thermoregulatory mechanisms remain intact in heat exhaustion
Heat stroke is when mechanism fails
diagnosis of heat stroke
Exposure to heat stress, endogenous or exogenous
Signs of severe CNS disfunction (coma seizures delirium)
Core temperature usually above 40.5 Celsius but maybe lower
Hot skin calming and sweating may persist
Marked elevation of hepatic transaminase levels
What are the two forms of heat stroke
Classic and exertional
Characteristics of exertional heat stroke
Younger healthy individuals Exercise Sporadic Diaphoresis Hypoglycaemia DIC Rhabdomyolysis Acute renal failure Marked lactic acidosis hypocalcaemia
Features of classic heat stroke
Older individuals with predisposing factors or medications Sedentary Heat wave occurrence Anhidrosis Normoglycemia Mild coagulopathy Mild to CK elevation Oliguria Mild acidosis Normal calcium
Ddx of heatstroke
CNS hemorrhage Toxins, drugs - anticholinergic poisoning, sympathomimetics Seizures Malignant hyperthermia Neuroleptic malignant syndrome Serotonin syndrome Thyroid storm High fever, sepsis Encephalitis, meningitis Typhoid fevers Delirium tremens Hypothalamic hemorrhage
Investigations for patient with heat stroke
ABG, CBC, lytes- extended, glucose, urea/Cr, CK, myoglobin and UA, transaminases, PTT, INR, lactate, troponin
How to cool patients with heat stroke
Preferred method : evaporative with large fans and skin wetting ; ice water immersion
Adjuncts Ice packs to axilla and groin Cooling blanket Peritoneal lavage Recital lavage Gastric lavage Cardiopulmonary bypass
Resuscitation of a patient with heat stroke
Airway control - seizures and aspiration common
Crystalloid fluid resus
Tachyarrhythnias usually resolve with cooling - avoid cardio version until myocardium cooled, avoid used of alpha adreneriv agents becuase they promote vasoconstriction and decrease cutaneous heat exchange and may exacerbate renal and hepatic damage
Atropine and antichokinfeics that inhibit sweating should be avoided
If rhabdo keep urine output at least 2ml/kg/he
Urinary alkalinization considered in patients with acids is, dehydration, or underlying renal diseS
Can give mannitol after volume to increase intravasuckar volume and gfr but don’t use if oliguria
Benzos for shivering
What percentage of dogbite get infected and which sites are at higher risk
2 to 30%
Hand bites are at higher risk for infection
Face and scalp or a lower risk for infection
Puncture wounds at higher risk for infection than avulsions and lacerations
What types of bacteria are typically involved in dogbite wound infection
Often polynicrobial
Pasteurella
Other aerobics: strep, staph, Neisseria, Corynebacterium, Moraxella
Anaerobic: Fusobacterium, Bacteroides, Porphyromonas, Prevotella, and Propionibacterium
Capnocytophaga canimorsus
3 days typically (can be 1-10 after bite) pt develops fever, V/D, abdo pain, headache, confusion with purpuric lesions
Can also progress to endocarditis, meningitis
Capnocytophaga canimorsus
What patients typically affected by capnocytophaga canimorsus
Middle aged men
Underlying medical problems most often alcoholism, splenectomy, or immunosuppression
What factors are high risk for bite wound infection
Species: cat, human, monkey, pig, camel, bear
Location: hand, foot
Wound type: puncture, crush injury, presence of divitalized tissue, delayed presentation (6 hours later), closed primarily
Patient characteristics: age over 50, diabetes, renal failure, liver dz, alcoholism, immune disorder, malnutrition, use of steroids or immunosuppressants, peripheral vascular disease, chronic edema of bitten area
What antibiotics to use for dog bite and next lines if pen allergic
Amoxicillin-clavulanate
Clindamycin + septra or cipro
Moxifloxacin
Antibiotics for dog and cat bites requiring hospital admission
Ampicillin/sulbactam
Piptazo
Ticarcillin/clavulanate
Clindamycin + cipro or septra
Indications for admission after animal bite
Structural
- injury to deep structures (bones, joints, tendons, arteries, nerves)
- injury requiring reconstructive surgery
- injuries requiring GA for appropriate wound care
Infectious
- rapidly spreading cellulitis
- significant lymphangitis or lymphadenitis
- infection of patients at high risk for complications
- infection with failed outpatient therapy
Antibiotic prophylaxis for human and monkey bites
Amoxclav
Moxifloxacin
Cefoxitin
Clindamycin plus penicillin or cipro
Antibiotics for human and monkey bite if requires admission
Amp/sulbactam Piptazo Ticarcillin/clav Imipenem Meropenem Ertapenem Clindamycin plus pen or cipro
Antibiotic prophylaxis and inpatient treatment of rodent bites
Not recommended
Treatment of ferret, pig, horse, bear, big cats, coyotes, wolves bites
Same as dog / cat
Abx prophylaxis after camel bite and treatment if admitted
Ciprofloxacin
Ofloxacin
And inpatient to same as cats and dogs
Rate of dog bite infection
2-30%
Rate of cat bite infection
80%
What is the major concern for exposure in monkey bites and what is it
B virus which is similar to HSV and causes vesicular lesions at site of exposure with flu like symptoms incubation period 2 days to 5 weeks
Can develop paresthesiS and muscle weakness
CNS involvement can occur which include AMS, CN palsies, ataxia, coma, respiratory failure
If left untreated mortality rate is 80%
Management of monkey bites
Area scrubbed with soap, or iodine, chlorhexidine then irrigated with running water for 15-20 mins
Prophylaxis with valacyclovir after high risk bites can be offered up to 5 days after bite but should be started ASAP
Treatment of suspected B virus infection
IV acyclovir or ganciclovir
When is prophylaxis for monkey B virus recommended
Skin exposure (with loss of skin integrity) or mucosal exposure to a high risk source (macaque that is ill, immunocompromised, known to be shedding virus or lesions compatible with B virus)
Inadequately cleaned skin exposure or mucosal exposure to any macaque
Deep puncture bite
Laceration of head, neck, torso
Needle stick associated with tissue or fluid from the nervous system, eyelids, mucosa, or lesions suspicious for B virus
Puncture or lacerations after exposure to objects contaminated with either fluid from monkey oral, genital, or nervous system tissues or any object known to be contaminated with B virus
A post wound cleaning culture is positive for B virus
What other situations can prophylaxis be considered for monkey virus B exposure
Mucosal splash that has been adequately cleaned
Laceration that was been adequately cleaned
Puncture or lac occurring after exposure to either objects contaminated with body fluid or potentially infected cell culture
Dosing for monkey virus B prophylaxis
Valacyclovir 1g TID for 14 days
Or acyclovir 800ng five times a day for 14 days
When is monkey virus B prophylaxis not recommended
Skin exposure when skin remains in tact
Exposure associated with non macaque species of non human primates
What is rat bite fever
Caused by Streptobacillus moniliformis or Spirillum minus
Can occur by bite, scratch or simply handling a rat
Incubation 3 days to 3 weeks
Fever, migratory polyarthralgias, maculopapular, petechial, or purpurin rash
Untreated has 10% mortality
Treatment of rat bite fever
IV penicillin
Streptomycin and tetracycline in penallergic patients
Rates of infection after clenched fist injury (fight bite)
Osteomyelitis- 16%
Septic arthritis- 12%
Tenosynovitis - 22%
Management of bites to oral mucosa or through and through injury
Prophylaxis of penicillin for lacs requiring primary closure and those that result in mucocutaneous communication
Bacteria found in human bites
Eikenella corrodens
Staph, strep, corynebacterium, fusobacterium
Work up of fight bite
Hand X-ray to look for retained teeth, deep structure injuries
When can you suture dog bites
Most except hands and feet
When to suture cat bite
Face only
When can you suture human bite or monkey
Fave only (up to 24 h after bite)
When to suture rodent bite
Any but rarely needed
When to suture ferret, pig, horse, camel, bear, big cats
Face only
Management of fight bite
Wound exploration through entire ROM, including closed fist when fingers are flexed, because extensor tendons and cartilage damage may not be evident in other positions
If joint, tendon or bone injury should be admitted for open debridenent and irrigation in OR - same if they present later with infected wound
think about post exposure prophylaxis if either party is known HIV positive or at high risk and blood exposure occurred, prophylaxis also indicated if HBV positive or high risk or blood/saliva exposure has occurred
Indications for admission for human bites to the hand
Infection at time of Presbyterian
Deep structure violations
Wound requiring OR
Patients at high risk for wound infection
Patients with likely social support or compliance issues
components of a focused Dive history
onset of symptoms?
type of equipment used - compressed air, mixed gas, enriched air, rebreather ? - what was source of gas
did dive approach or exceed decompression limits
was a dive computer used?
what were the number, depth, bottom time, total time and surface intervals for all dives in the 72 hours preceding symptoms
were decompression stops used? was in-water decompression attempted?
what was the time delay from last dive to air travel?
did diver experience difficulty with ear or sinus equilibration ? did pain occur n descent or ascent
was diver intoxicated, dehydrated, or working strenuously
how long after dive did symptoms start, were they present at surfacing, delayed? progressive?
is med hx of ear or sinus infections or abnormalities present? emphysema or asthma ? CAD? PFO ? neuro illness?
disorders that occur during descent when diving
middle ear barotrauma external ear barotrauma inner ear barotrauma barosinusitis facial barotrauma
disorders that arise at depth when diving
nitrogen narcosis
oxygen toxicity
contaminated air
disorders that arise during ascent when diving
alternobaric vertigo barodontalgia GI barotrauma pulmonary barotrauma decompressino sickness arterial gas emoblism pulmonary edema
What happens in middle ear barotrauma when diving
During descent - unsuccessful equalization causes pressure on tm,
Can cause tm rupture leading to cold water entering middle ear and causing caloric stimulation with transient nystagmus and vertigo - can also lead to 7th nerve palsy
What happens in external ear barotrauma when descent diving
When external auditory canal is obstructed by wax, stenosis, etc it can trap air and cause negative pressure leading to pain and or hemorrhage of the EAC
What happens in inner ear barotrauma upon descent when diving
Large negative pressure builds and inward deflection of tm transmits to oval window of cochlea which causes a pressure wave in perilymph which distended round window - sudden equlibratipn or valsalva and lead to hemorrhage in inner ear or tear the labyrinthine (reissner’s) membrane
Symptoms are hearing loss, vertigo, nausea, tinnitus and fullness in affected ear
Signs bare nystagmus positional vertigo ataxia and vomiting
Can be challenging to distinguish from inner ear DCS
What is barosinusitis which occurs on descent in diving
Obstruction of sinus Ostia causes sinus barotrauma
Most often maxillary or frontal sinus and causes facial pain and epistaxis
What happens with facial barotrauma with descent from diving
Pressure within dive mask over eyes and nose - if don’t equalize can cause facial and conjunctival edema, petechial hemorrhages on face and subconjunctival hemorrhage
What is nitrogen narcosis
Intoxicating effects of increased tissue nitrogen concentration at depth
Euphoria, false feeling of well being, confusion, loss of judgement or skill disorientation inappropriate laughter diminished motor control and tingling in the vague treatment numbness of the lips and gums and legs
Occurs typically at deptus below 150 feet
