Environmental Medicine

1. 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

3. Hypothermia

4. Hypothermia Definition Core temp < 35 degrees Derangement of multiple organ systems Shivering increases metabolic rate, but require glycogen stores and only if core > 30 degrees Grading Mild Moderate Severe Epidemiology Increased children (SA:mass ration) Elderly (<metabolic heat production) Men > women Environmental Medicine

5. 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) Environmental Medicine

6. CVS Initially Tachy, periph vasoconstriction Bradycardia, hT Jwaves temp < 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 > 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 < 30 Environmental Medicine

7. CNS Fine then gross motor skills Progressive < GCS CNS autoreg <24 deg Rigid, dilated pupils, areflexic < 28 deg Resp Tachypnoea followed by depression < O2 consumption, CO2 production Hypoventilation, apnoea, APO acidosis Environmental Medicine

8. Renal Diuresis initially <CO - <GFR ARF >BSL if rapid hypothermia <BSL slow hypother, depleted glycogen stores Renal <K+ (moves intracellular) Then >K+ metabolic acidosis and cell death Increased cardiotox to K+ at low temp Risk hypoPO4 with rewarming Environmental Medicine

9. GIT < motility Ileus <28 deg Hep impairment affects drug t1/2 Pancreatitis Mesenteric venous thrombosis Haem > viscosity, haemoconcentration, hypovol, + diuresis Coagulopathy Tcp/DIC Environmental Medicine

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

11. Environmental Medicine • Moderate (28-32deg) • Stupor • No shiver, muscular rigidity • AF, arrhythmias • Brady, < CO, hypotension • Progressive <GCS, <PR, <RR, pupils dilated • Risk of VF

12. Environmental Medicine • Severe (<28deg) • Loss volunt m’ment and reflexes, fixed dilated pupils, coma • Major acid/base disturbance • <CO, < cerebral flow • hT ++, bradycardia ++, slow AF • APO • Risk VF +++ at 22deg, Asystole • Flat EEG

13. Ix Mild : none Mod/severe Look for precipitants /complications U+E / Cr BSL Ca2+/Mg2+/PO4- Lipase/LFT CK EtOH Mod/severe FBE Clotting ABG (don’t adjust for temp) CXR +/- trauma XR ECG + monitoring Environmental Medicine

14. 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 < heat loss Gentle handling Arrhythmias Slow AF is common and benign – don’t correct with drugs or DCR VF/VT Single DC shock If unsuccessful, must rewarm and rpt with every 1 degree > core temp Environmental Medicine

15. Rewarming Endogenous – mild <T Require some endogenous thermogenesis Warm env, warm clothing, insulation Passive external – mild <T Warm blankets, space blanket Active External – mod <T Forced air warming blanket (Bair Hugger) Active core rewarming – severe <T ETT, Warmed inhaled O2 (42-46deg) Warm IV fluid (40-42deg) warm pleural lavage through chest tubes ECMO/Bypass Environmental Medicine

16. Heat illness

17. Heat Wave • End Jan-Feb 09 • 3 consecutive days >43, max temp 15deg above average, overnight low 26deg • 46.4 degrees • 374 extra deaths in Victoria (Black Sat – 173) • 248 > 75yo, 46: 65-74yo • 3 x increase DOE in EDs • 77% increase deaths reported to coroner • Ambulance 1600 jobs/d c/f 800

18. Environmental Medicine • Heat related illness • Heat stroke • Definition • Core temp >41deg • Classic heat stroke • Exposure to high environmental temp • Patients with impaired thermostatic mechanisms • Exertional heat stroke • Strenuous exercise • Failure of hypothalamic thermostat

19. Risk factors Env – high temp/humid Age – infants/elderly Physical Obese Dehyd/alcohol Clothing Intercurrent illness unfit Medical CF, DM, >T4 Parkinsons, IHD, epilepsy Medications antiCh : Li, TCAD, phenothiazines <CO – Ca/beta blockers Diuretics – dehyd Serotonin, NMS, malignant hyperthermia Environmental Medicine

20. CVS Tachyarrhythmia/hT 1. hyperdynamic Tachy, high CO 2. hypodynamic <CO, >PVR CNS Delirium, lethargy, coma, seizures Cerebellum most vulnerable Transient or permanent neurological injury Rhabdomyolysis Damaged cells leak Ca/PO4 K+ initially <, then > and ARF >uricaemia Renal ARF in 30% pt 2 to direct thermal injury, hypoperfusion, rhabdo, DIC Haem Haemorrhagic complications, ecchymoses, DIC Gut ischaemia Environmental Medicine

21. 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

22. Investigations U+E - <K+, >PO4, >Ca+, then >K+, renal impairment Urate – increased (contribute to ARF) Gluc - > in 75% LFT – very common, >AST/LDH CK – usually >10,000 WBC – up to 40 Clotting – DIC ABG – lactic acidosis, resp alkalosis, then metabolic acidosis Urine myoglobin > ECG Arryth – ST, AF, SVT Conduction- RBBB, IV conduction delay QT>, ST changes CXR Aspiration, ARDS Environmental Medicine

23. Heat stroke - management

24. Management Mortality 80% if not treated promptly Rapid cooling = < 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 Environmental Medicine

25. 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 Environmental Medicine

26. Environmental Medicine • Complications • CNS • Encephalopathy, oedema, haemorrhage, necrosis • Hepatic/panc damage • CVS – myocardial injury • ARF • Resp – ARDS • DIC • Mortality <10% with prompt Rx

27. 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

28. 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 Environmental Medicine

29. 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) Environmental Medicine

30. Electricity

31. Electricity 80 fatalities / year Australia Male, young If survive initial shock, subsequent death unlikely Presence of water > fatality Electricity Severity Voltage >1000volts Current > 100mAmp – can precip VF/Resp arrest >2 amps – burns >10amps – 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 Environmental Medicine

32. Injury Resembles crush injury more that burn Damage below the skin >> 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 Environmental Medicine

33. Management General Isolate source Consider Cspine injury Monitor >1000volt 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 Environmental Medicine

34. 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, O+G consult

35. 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

36. 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 Environmental Medicine

37. 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 Environmental Medicine

39. 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’

40. Submersion injury

41. Environmental Medicine • Submersion injury • Drowning: death (<24/24) by suffocation in liquid • Near Drowning: survival (>24/24) following asphyxia secondary to submersion • Secondary drowning: death >24/24 from complications

42. 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, male:female 5:1 • Alcohol in adolescent/adult up to 50%

43. 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 <10% lung volume, but dramatic effect Environmental Medicine

44. 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

45. 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

46. Environmental Medicine • Assessment • Ix • ABG • U+E – 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

47. Management Cat A Symptomatic Rx Obs for >6/24 – monitor for APO Nil oral oxygen Cat B + C Aggressive resus at scene Resp arrest < cardiac arrest heartbeat with no spont resp or palp pulse Environmental Medicine

48. 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 Environmental Medicine

49. Environmental Medicine • Management • Hypothermia • Gentle handling • CPR only if asystole or documented VF • Temp <28 withhold CPR if motor activity present • Rewarming

50. Environmental Medicine • Prognosis • 1 or 2 = 90% good recovery, >3 5% recovery • Age <3 • Submersion >5min • No resus first 10min post rescue • Coma O/A to ED • pH < 7.1 • GCS • Neuro improvement 2-6/24 post rescue, good recovery, if not poor recovery