Environmental Medicine

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Environmental Medicine
Andre Vanzyl Senior Medical Staff Monash Medical
Centre
2
Environmental Medicine

• Non-organic
• Hypo/hyperthermia
• Electrical injury
• Submersion/diving/high altitued
• Organic
• Envenomations
• Spider
• Snake
• marine

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Hypothermia
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Environmental Medicine

• Hypothermia
• Definition
• Core temp lt 35 degrees
• Derangement of multiple organ systems
• Shivering increases metabolic rate, but require
  glycogen stores and only if core gt 30 degrees
• Grading
• Mild
• Moderate
• Severe

• Epidemiology
• Increased
• children (SAmass ration)
• Elderly (ltmetabolic heat production)
• Men gt women

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Environmental Medicine

• Neuro
• CVA
• Paraplegia
• Parkinsons
• Endo
• Hypoglycaemia
• Hypothyroid
• Hypoadrenalism
• Systemic
• Sepsis
• malnutrition

• Aetiology
• Environment
• cold/wet/windy
• Cold immersion
• Trauma
• Entrapment, HI
• Minor trauma with immobility (NOF)
• Major burns
• Drugs
• Alcohol/sedatives
• Phenothiazines (shiver)

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Environmental Medicine

• CVS
• Initially Tachy, periph vasoconstriction
• Bradycardia, hT
• Jwaves temp lt 32 deg
• a hump where the QRS complex joins the ST
  segment.

• 10bpm at 20 deg
• Risk asystole 24 deg
• AF VF asystole
• 2/3deg HB
• gt PR, QRS, QT interval
• Drugs
• Low efficacy at such low temp (adren/ligno)
• Consider dopamine after volume replacement for
  persistent hT
• Mg 2 for VF
• Defib ineffective T lt 30

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Environmental Medicine

• CNS
• Fine then gross motor skills
• Progressive lt GCS
• CNS autoreg lt24 deg
• Rigid, dilated pupils, areflexic lt 28 deg

• Resp
• Tachypnoea followed by depression
• lt O2 consumption, CO2 production
• Hypoventilation, apnoea, APO
• acidosis

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Environmental Medicine

• Renal
• Diuresis initially
• ltCO - ltGFR
• ARF
• gtBSL if rapid hypothermia
• ltBSL slow hypother, depleted glycogen stores

• Renal
• ltK (moves intracellular)
• Then gtK metabolic acidosis and cell death
• Increased cardiotox to K at low temp
• Risk hypoPO4 with rewarming

9
Environmental Medicine

• GIT
• lt motility
• Ileus lt28 deg
• Hep impairment affects drug t1/2
• Pancreatitis
• Mesenteric venous thrombosis

• Haem
• gt viscosity, haemoconcentration, hypovol,
  diuresis
• Coagulopathy
• Tcp/DIC

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Environmental Medicine

• Measure
• Rectal or oesophageal thermometer
• Mild (32-35deg)
• gt basal metabolic rate
• Shivering
• Amnesia, dysarthria, ataxia, apathy
• Maximum resp stim
• Normal BP, tachycardia

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Environmental Medicine

• Moderate (28-32deg)
• Stupor
• No shiver, muscular rigidity
• AF, arrhythmias
• Brady, lt CO, hypotension
• Progressive ltGCS, ltPR, ltRR, pupils dilated
• Risk of VF

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Environmental Medicine

• Severe (lt28deg)
• Loss volunt mment and reflexes, fixed dilated
  pupils, coma
• Major acid/base disturbance
• ltCO, lt cerebral flow
• hT , bradycardia , slow AF
• APO
• Risk VF at 22deg, Asystole
• Flat EEG

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Environmental Medicine

• Ix
• Mild none
• Mod/severe
• Look for precipitants /complications
• UE / Cr
• BSL
• Ca2/Mg2/PO4-
• Lipase/LFT
• CK
• EtOH

• Mod/severe
• FBE
• Clotting
• ABG (dont adjust for temp)
• CXR /- trauma XR
• ECG monitoring

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Environmental Medicine

• Management
• General
• ABC
• ETT
• IV, warm IV fluid resus, IDC, NGT,
• Cardiac monitor, temp
• Glucose muscle glycogen essential for shivering
• D5W at 200ml/hr
• Remove wet clothes, insulate to lt heat loss
• Gentle handling

• Arrhythmias
• Slow AF is common and benign dont correct with
  drugs or DCR
• VF/VT
• Single DC shock
• If unsuccessful, must rewarm and rpt with every 1
  degree gt core temp

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Environmental Medicine

• Rewarming
• Endogenous mild ltT
• Require some endogenous thermogenesis
• Warm env, warm clothing, insulation
• Passive external mild ltT
• Warm blankets, space blanket
• Active External mod ltT
• Forced air warming blanket (Bair Hugger)

• Active core rewarming severe ltT
• ETT, Warmed inhaled O2 (42-46deg)
• Warm IV fluid (40-42deg)
• warm pleural lavage through chest tubes
• ECMO/Bypass

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Heat illness
17
Heat Wave

• End Jan-Feb 09
• 3 consecutive days gt43, max temp 15deg above
  average, overnight low 26deg
• 46.4 degrees
• 374 extra deaths in Victoria (Black Sat 173)
• 248 gt 75yo, 46 65-74yo
• 3 x increase DOE in EDs
• 77 increase deaths reported to coroner
• Ambulance 1600 jobs/d c/f 800

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Environmental Medicine

• Heat related illness
• Heat stroke
• Definition
• Core temp gt41deg
• Classic heat stroke
• Exposure to high environmental temp
• Patients with impaired thermostatic mechanisms
• Exertional heat stroke
• Strenuous exercise
• Failure of hypothalamic thermostat

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Environmental Medicine

• Risk factors
• Env high temp/humid
• Age infants/elderly
• Physical
• Obese
• Dehyd/alcohol
• Clothing
• Intercurrent illness
• unfit

• Medical
• CF, DM, gtT4
• Parkinsons, IHD, epilepsy
• Medications
• antiCh Li, TCAD, phenothiazines
• ltCO Ca/beta blockers
• Diuretics dehyd
• Serotonin, NMS, malignant hyperthermia

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Environmental Medicine

• CVS
• Tachyarrhythmia/hT
• 1. hyperdynamic
• Tachy, high CO
• 2. hypodynamic
• ltCO, gtPVR
• CNS
• Delirium, lethargy, coma, seizures
• Cerebellum most vulnerable
• Transient or permanent neurological injury

• Rhabdomyolysis
• Damaged cells leak Ca/PO4
• K initially lt, then gt and ARF
• gturicaemia
• Renal
• ARF in 30 pt
• 2 to direct thermal injury, hypoperfusion,
  rhabdo, DIC
• Haem
• Haemorrhagic complications, ecchymoses, DIC
• Gut ischaemia

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Environmental Medicine

• Assessment
• Hx exposure to heat stress and alt consc state
• Triad
• Hyperthermia 41deg
• Neurological abnormalities/loss of consciousness
• Dry skin (may still sweat)
• Core temp rectal/oesophageal
• hT and shock hypovol, periph vasodil, cardiac
  dysfunction
• ST up to 150
• Hyperventilation
• Alt consc state delerium, ataxia, seizure, coma

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Environmental Medicine

• Investigations
• UE - ltK, gtPO4, gtCa, then gtK, renal impairment
• Urate increased (contribute to ARF)
• Gluc - gt in 75
• LFT very common, gtAST/LDH
• CK usually gt10,000
• WBC up to 40

• Clotting DIC
• ABG lactic acidosis, resp alkalosis, then
  metabolic acidosis
• Urine myoglobin gt
• ECG
• Arryth ST, AF, SVT
• Conduction- RBBB, IV conduction delay
• QTgt, ST changes
• CXR
• Aspiration, ARDS

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Heat stroke - management
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Environmental Medicine

• Management
• Mortality 80 if not treated promptly
• Rapid cooling lt mort
• AB
• Oxygen, ETT
• Coma, seizure, aspir are common complic
• Avoid Sux

• C
• Fluid deficit 2litres
• N/S or ½ N/S
• Monitor temp, HR, BP, ECG, urine, (?CVP)
• Inotrope
• avoidAdr/NA (decrease heat dissipation)
• Low dose Dopamine
• Disposition
• ICU

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Environmental Medicine

• Cooling
• Remove pt from heat
• Remove clothing
• Evap cooling
• Spray warm (32deg) water, fanning
• Ice water immersion
• Adv/disad
• Ice packs axilla/groin/neck
• Cold, wet towels
• Bypass

• Additional therapy
• Diazepam/CPZ to inhibit shivering
• Paralysis
• Avoid paracetamol/aspirin ineffective
• Support kidneys
• Fluid
• Mannitol/frusemide
• Urine alkalinisation
• Dialysis
• Rx coagulopathy FFP, plt

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Environmental Medicine

• Complications
• CNS
• Encephalopathy, oedema, haemorrhage, necrosis
• Hepatic/panc damage
• CVS myocardial injury
• ARF
• Resp ARDS
• DIC
• Mortality lt10 with prompt Rx

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Environmental Medicine

• Serotonin syndrome
• CNS
• Confusion
• Agitation/hypomania
• Hallucinations
• Seizures
• ANS
• Hyperthermia/sweats
• Tachycardia
• HT/hT
• Neuromuscular
• Increased M tone/rigidity
• Hyperreflexia
• Ataxia

• Sources
• Usually a combination of drugs which increase
  central serotonin
• Majority occur at therapeutic levels, not OD
• MAO/SSRI
• Lithium
• TCA
• Tramadol
• Treatment
• Cyproheptadine
• CPZ
• RSI/paralysis

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Environmental Medicine

• NEUROLEPTIC MALIGNANT
• CNS
• Confusion/agitation
• Coma/seizures
• ANS
• Hyperthermia/sweats
• Tachycardia
• HT/hT
• Neuromuscular
• Lead pipe rigidity
• tremor

• Sources
• Antipsychotic drugs
• Can occur at anytime during treatment or on
  withdrawal
• Treatment
• Supportive
• Cooling
• Fluid replacement
• BZD
• Dantrolene/bromocriptine

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Environmental Medicine

• MALIGNANT HYPERTHERMIA
• Genetically inherited disorder, triggers release
  of sarcoplasmic Ca2
• hyperthermia
• Acidosis
• Rhabdomyolysis
• Can be delayed px
• UnRx mort 70

• Sources
• Anaesthetic agents
• Halothane
• Isoflurane
• Ketamine
• FHx
• Treatment
• Dantrolene (inhibit Ca2 release from
  sarcoplasmic reticulum)

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Electricity
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Environmental Medicine

• Electricity
• 80 fatalities / year Australia
• Male, young
• If survive initial shock, subsequent death
  unlikely
• Presence of water gt fatality

• Electricity
• Severity
• Voltage gt1000volts
• Current
• gt 100mAmp can precip VF/Resp arrest
• gt2 amps burns
• gt10amps asystole
• Resistance
• Wet skin conducts 25x better
• Type AC more likely to precip VF
• Pathway hand to hand more dangerous
• Duration lightning high volts, but v brief

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Environmental Medicine

• Injury
• Resembles crush injury more that burn
• Damage below the skin gtgt than appears
  superficially
• Size of entry/exit wounds do not correlate with
  damage
• Direct electrical
• Vascular spasm, thromb
• Neurological injury
• Muscle necrosis
• Thermal burns
• Flame burns (clothing)
• Lightning splash
• Blast injury

• CVS
• mainly VF. Delayed arrhythmia resulting in death
  is exceptionally rare.
• Sinus tachy common
• CNS
• Resp arrest, seizure
• Alt GCS, amnesia, coma
• Delayed
• Spinal cord injury
• Peripheral nerve injury
• Eye - catarcts
• Renal myoglobinuria/ARF
• Organ injuries
• Colon, Panc, GB, SI
• Musculoskeletal
• Compression vertebrae, long bones
• dislocations

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Environmental Medicine

• Management
• General
• Isolate source
• Consider Cspine injury
• Monitor
• gt1000volt
• Seizures
• ECG changes or arrhythmia

• ABC
• Defib (VF most common)
• C spine precautions
• AB - ETT
• CPR, Monitor and Rx arrhythmia
• Monitor not required for pt who is ASx and normal
  ECG
• Fluid resus, Monitor renal function
• Manage burns
• ADT
• Analgesia

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Environmental Medicine

• Electricity v. pregnancy
• High mortality
• Fetus has less resistance to electrical shock,
  small shock can be fatal
• Uterus and amniotic fluid excellent conductors
• Urgent USS and foetal monitoring, OG consult

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Environmental Medicine

• Electricity
• Disposition
• Majority can be discharged after assessment and
  reassurance
• Analgesia for muscle aches, GP r/v
• Cardiac arrhythmia require admission for
  observation until arrhythmia resolves
• Neuropathy neurology f/up, N conduction studies
• Severe electrical injury with burns require
  admission /- ICU

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Environmental Medicine

• Lightning
• 2-3 deaths / year Australia
• 1 death to 5 injuries
• Risk of long term impairment is low
• Victim is NOT charged, not dangerous to touch

• Immediate effects
• Cardiac arrest/asystole
• CP, muscle aches
• Neuro deficits
• Unconscious
• Mute, unable to move
• Contusions from shock waves
• Tympanic membrane rupture

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Environmental Medicine

• Lightning
• Delayed effects
• Limb paralysis is v. common, mottled, pale,
  impalpable pulse, query secondary to vasospasm.
  Resolves 1-6 hrs
• Lichtenberg flowers
• Feathery cutaneous burns
• Immediate
• Or after few hrs
• Cataracts
• CNS
• Sensorineural deafness
• Vestibular dysfunctions

• CNS
• Sensorineural deafness
• Vestibular dysfunction
• Retinal detachment
• Optic nerve damage
• Pregnancy
• High rate FDIU

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Environmental Medicine

• Lightning
• Mx
• Prehospital
• Immediate BLS/ALS prevents secondary hypoxic
  injury
• Fixed dilated pupils does not equal death
• ED
• Consider if pt found outdoors in stormy weather
• Standard ABC measures
• Examine ears (tympanic) eyes (lens defect,
  retinal detachment, optic nerve injury)
• CT?
• ECG
• Manage burns
• Limb paralysis expectant Mx
• Admit
• Abnormal MSE or ECG
• Significant burns or traumatic C

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Submersion injury
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Environmental Medicine

• Submersion injury
• Drowning death (lt24/24) by suffocation in liquid
• Near Drowning survival (gt24/24) following
  asphyxia secondary to submersion
• Secondary drowning death gt24/24 from
  complications

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Environmental Medicine

• Epidemiology
• Driest inhabited continent, highest reported
  incidence of drowning in the world
• 2nd most common cause of death in kids
• 50 0-4yo, highest rate 1-2yo, malefemale 51
• Alcohol in adolescent/adult up to 50

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Environmental Medicine

• Pathophysiology
• Panic, breath holding, then involuntary breath ?
  bronchoconstriction, pulmonary HT,
  vomit/aspirate, involuntary gasping respirations
  flood lungs
• Aspiration 85
• wet drowning
• Laryngospasm 15
• Dry drowning
• Hypoxia, LOC, cerebral oedema, seizures
• bradycardia, irreversible brain injury 3-10min

• Pulmonary oedema
• Exudate floods alveoli
• Surfactant loss atelectasis
• Pulmonary vasoconstriction, increased Pulm P,
  further fluid shift
• May take minutes to days to develop
• Average amount of fluid in lungs is lt10 lung
  volume, but dramatic effect

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Environmental Medicine

• Assessment
• Hx
• Time of submersion
• Type and temp of water, contamination
• Time till respiration/CO resumed
• Type and timing of resuscitation
• Associated trauma
• Co-morbidities
• NAI

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Environmental Medicine

• Assessment
• Examination
• Classification at 2/24 post immersion
• Cat A awake
• Cat B conscious but obtunded
• Cat C comatose
• Other
• Temp
• Cardiac rhythm
• Resp pattern
• HI/Cx trauma
• APO

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Environmental Medicine

• Assessment
• Ix
• ABG
• UE ARF uncommon, usually 2 to hypoxia
• Osmolarity
• Blood alcohol
• CXR bilat infiltrates, non cardiogenic APO
• C spine
• Skeletal survey NAI
• FBE, INR, APTT coagulopathy
• CT head focal signs, significant trauma

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Environmental Medicine

• Management
• Cat A
• Symptomatic Rx
• Obs for gt6/24 monitor for APO
• Nil oral
• oxygen

• Cat B C
• Aggressive resus at scene
• Resp arrest lt cardiac arrest
• heartbeat with no spont resp or palp pulse

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Environmental Medicine

• Management
• Ventilation
• APO can make ventilation difficult
• CPAP
• Low threshold for ETT and PEEP
• Rx bronchospasm
• No evidence for proph AB

• Encephalopathy
• Supportive Mx to maintain CNS oxygen
• Normoglycaemia
• Query cooling (CNS protect)
• Rx Seizures
• No evidence steroids

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Environmental Medicine

• Management
• Hypothermia
• Gentle handling
• CPR only if asystole or documented VF
• Temp lt28 withhold CPR if motor activity present
• Rewarming

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Environmental Medicine

• Prognosis
• 1 or 2 90 good recovery, gt3 5 recovery
• Age lt3
• Submersion gt5min
• No resus first 10min post rescue
• Coma O/A to ED
• pH lt 7.1
• GCS
• Neuro improvement 2-6/24 post rescue, good
  recovery, if not poor recovery

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Drowning Adrenaline
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Diving medicine
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Environmental Medicine

• Diving Medicine
• Boyles Law volume gas varies inversely with
  pressure
• Barotrauma occurs when changes in ambient
  pressure lead to expansion or contraction of gas
  within enclosed body cavities
• Sites
• Middle ear, inner ear, sinus
• Lungs
• Pneumothorax
• Pneumomediastinum
• Arterial gas embolism
• GIT, Dental

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Environmental Medicine

• Diving medicine
• Classification Decompression Illness (DCI)
• Decompression sickness
• N2 bubbles coming out of tissues
• AGE
• Pulmonary barotrauma releasing air into
  circulation
• But difficult to distinguish, identical
  management
• Symptomatic classification
• Acute/chronic
• Evolution of Sx static/progressive/relapsing
• Organ systems involved
• DCI
• Presence/absence barotrauma

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Environmental Medicine

• DCI
• Path
• Intra/extra vascular bubble of gas
• From gas diffusing out of tissues (as P lt) or
  from pulmonary barotrauma
• Amount of N2 depends on depth and time
• Slow ascent, N2 diffuses out of tissues, via
  blood, eliminated by lungs
• Pulmonary barotrauma allows gas to enter
  circulation, resulting in arterial gas embolism
  (AGE)
• Most tissue damage is a consequence of secondary
  inflammation of the vascular endothelium, not the
  bubbles themselves

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Environmental Medicine

• Diving Medicine
• Arterial gas embolism (AGE)
• Second to drowning as cause of death in diving
• Occurs on ascent gt pulm barotrauma
• Alveolar rupture, entry of gas to pulm cap
• Bubbles enter systemic circulation, mainly CNS
• Sudden onset LOC, focal neurology (asymetrical
  multiplegia), death
• Cardiac arrhythmias, ischaemia
• Pulmonary oedema

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Environmental Medicine

• AGE
• Hx
• Difficult to differentiate from decompression
  illness
• Onset 0 20 min post surfacing
• CNS air ? vasogenic oedema 30min to 24/24
• Seizure/LOC, confusion, headache, visual change
• Spontaneous recovery, then may relapse

• Ex
• Subtle neuro changes
• Alt conscious state
• Focal neurology
• Blindness
• APO
• Ix
• CXR bubbles of air
• CT to exclude dDx

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Environmental Medicine

• AGE
• Mx
• Supportive care, ABC,
• Oxygen
• IVT maintain hydration
• Keep in supine position, ? Head down (gt CVS risk)
• Hyperbaric Tx
• Acute lt bubble size, improve oxygenation isch
  tissues
• gt N2 partial P gradient, so N2 goes into solution
• Mannitol only if impending herniation
• Transport at sea level

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Environmental Medicine

• Decompression Illness
• RF
• Obesity
• Smokers/alcohol
• Exercise
• Cold
• Dehydration
• Multiple dives
• Air travel post diving

• Time of onset
• Depth and duration dive
• 95 within 4/24

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Environmental Medicine

• Decompression illness
• Assessment
• Pain large joints, pelvic/shoulder girdle
• CNS
• LOC, alter behaviour/intellect/speech
• Cranial nerves
• Focal motor/sensory
• Loss balance/co-ord
• Loss sphincter control
• Spinal cord involvement in 60

• Audiovestibular
• N/V
• Vertigo/tinnitus
• Nystagmus/hearing loss
• Pulmonary
• CP
• Cough/dyspnoea
• Haemoptysis
• Cyanosis, collapse
• Rombergs test
• Stand heel/toe, palm on opposite shoulder, close
  eyes
• lt60sec suggestive of DCI

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Environmental Medicine

• Investigations
• FBE volume depletion
• Elec usually normal
• BSL
• CXR PTX
• CT/MRI no role in acute investigation of DCI,
  dont delay recompression

• Management
• Supportive, ABC
• Oxygen 100, ETT (N/S)
• Supine/left lat position
• Trendelenburg gtcerebral oedema
• Rx hyperthermia
• Aspirin
• Transport to compression chamber
• Hyperbaric Tx
• Decrease size of bubble, increase O2 delivery
• Several Rx over days
• Advised even if pt is ASx after first aid (risk
  relapse)
• Other
• Steroids, NSAID, Heparin ???

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Altitude
63
Environmental Medicine

• High Altitude Medicine

ALTITUDE P (mmHg) PiO2
Sea level 760 150
1000m 670 140
2000m 600 120
5,500m 380 70
8,848 240 40
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Environmental Medicine

• Acute mountain sickness (AMS)
• Continuum with HACE
• CNS change due to cerebral oedema
• Related to
• Rate of ascent
• Altitude reached
• Sleeping altitude
• PHx of AMS

• 50 people at gt4000m
• Progresses to life threatening HACE in 1-2
  people at gt4500m

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Environmental Medicine

• AMS
• Ax
• Mild
• Headache
• Malaise/insomnia
• Anorexia, N/V
• Severe
• Dyspnoea
• Ataxia (must descend)
• Alt conscious state
• Prophylaxis
• Acetazolamide 5mg/kg/d in divided doses (bd)
• Diuresis, ltCSF formation, gtventil drive
• One day prior, and one day after ascent

• Mx - Depends on severity
• Descent gt500m or until Sx reduce
• Acetazolamide if mild
• Dexamethasone
• 4mg qid
• Oxygen /- hyperbaric
• Analgesia, anti N/V, diuretics
• Hydration

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Environmental Medicine

• High Altitude Cerebral oedema (HACE)
• General
• Progression of Sx and Snx in setting of AMS
• Truncal ataxia
• Lethargy, alt consc state, coma
• Progresses over 1-3 days

• Mx
• Immed descent gt1000m or evacuation
• Oxygen
• Dexa 8mg stat, 4mg qid
• Hyperbaric O2
• Prolonged recovery

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HACE
68
Environmental Medicine

• High altitude Pulmonary Oedema (HAPO)

• Mech
• Non CVS pulm oedema
• Usually first 2/4days ascent gt 2500m
• More common males/kids
• Related to rate of ascent, exertion, cold

• Ax
• Cough, dyspnoea
• Tachycardia/pnoea
• Cyanosis
• Crepitations
• Interstitial and alveolar infiltrates
• Frothy sputum

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Environmental Medicine

• High altitude Pulmonary Oedema (HAPO)

• Mx
• Descend or evacuate
• Rest, warm, no exertion
• O2 (hyperbaric)
• CPAP
• Nifedipine 10mg stat
• lt pulm HT
• Dexa only if HACE
• Frusemide if not dehyd

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HAPE