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A Story of an Unfortunate Man

A Story of an Unfortunate Man. …which coincidentally teaches some environmental nuggets. Are you sitting comfortably?. There once was a man called Jack. Jack was an avid reader. One day he was basking in the midday sun, reading his Roald Dahl book, when he realised he felt a bit hot….

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A Story of an Unfortunate Man

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  1. A Story of an Unfortunate Man …which coincidentally teaches some environmental nuggets

  2. Are you sitting comfortably? There once was a man called Jack. Jack was an avid reader. One day he was basking in the midday sun, reading his Roald Dahl book, when he realised he felt a bit hot…

  3. Jack Had Hyperthermia. • Luckily a passing nurse found him and took him immediately to Auckland ED.

  4. Stage 1 • Heat exhaustion • Volume and electrolyte loss as sweat, with inadequate replacement • Still have heat regulatory mechanisms and CNS not affected

  5. Stage 2 • Heat stroke • Life threatening • Mortality <10% if treated, approaches 80% if not • T >40 degrees • >42 degrees  uncoupling of oxidative phosphorylation  cellular damage, failure of hypothalamic thermostat, inflammatory and coagulopathic stuff • Altered LOC (delirium, seizures, coma) • MOF • Not necessarily dehydrated

  6. Classical heat stroke • Due to high environmental T • Young and elderly • Hot and dry • Exertional heat stroke • Due to physical activity • Athletes and military • To acclimatise must exercise 60-90mins/day; still takes up to 2/52 and max at 3/12 • Hot and sweaty • Dehydration more common

  7. 80% hyperdynamic (ie. Incr CO), • 20% hypodynamic (ie. Distributive / high output shock) • Ataxia occurs early • Seizures, esp during cooling • lactic acidosis, respalkalosis, rhabdo, DIC, electrolyte disturbance • Organ failure • Prolonged QTc, ST changes

  8. It’s not only the sun… • Jack could have: • Hypethyroidism, sepsis, DT’s, epilepsy, dermatological problem, spinal injury… • Anticholinergic / serotonin syndrome, malignant hyperthermia, neuroleptic malignant syndrome

  9. What should Auckland ED do?

  10. What should Auckland ED do? • A+B: avoid sux • C: IVF resus only if dehydrated • If rhabdo: aim UO 50-100ml/hr • can use mannitol / frusemide to increase UO • consider urinary alkalinisation • Beware high output cardiac failure  puloedema • If need pressors avoid E+NE • Can cause vasoconstriction and hence prevent heat dissipation • Treat coagulopathy • D: can use sedatives / paralyse to decrease shivering

  11. Jack was made cool… • Evaporative • Ice water immersion • Ice packs • Cooling blankets • Cooled IV fluids • Gastric lavage etc…

  12. Jack recovered well… • Except for some residual ataxia (20% have a permanent residual neurological deficit)

  13. Unfortunately… • The over-enthusiastic doctor was rather rigorous with the cooling… • He was found by a FED who came to offer him a sandwich.

  14. The SSU nurse did a routine ECG… No prognostic significance Osborn wave Long QT Wide QRS AF with slow ventricular response in 50% with mod hypothermia

  15. Jack had Hypothermia. • Mild: <35 degrees • Shivering; ataxia, dyasthria, apathy • Incr HR / RR, resp alkalosis, peripheral vasoconstriction • Mod: <32 degrees • Failure of thermogenesis (no shivering, decr metabolism) • Initial cold-induced diuresis (don’t trust UO) • Decr LOC / HR / RR, resp acidosis, arrhythmia, stupor • Severe: <28 degrees • Loss of reflexes and voluntary motion, pupil dilatation, rigidity (initially the nurse thought Jack was dead…) • Puloedema, peripheral vasodilation, rhabdo, MOF, haemoconcentration and intravascular thrombosis

  16. It’s not only enthusiastic doctors… • Drugs (eg. ETOH, sedatives), dermal disease, massive blood / fluid loss, elderly, neonates, hypothyroid / adrenal / glycaemia, neuropathies • …and cold weather / exposure

  17. 35 Mild hypothermia • Mod hypothermia: shivering stops AF and other arrhythmias; 2/3 decr in HR and CO; Osborn waves common Decr RR/LOC Insulin resistance 31 Shivering stops (24-35, very variable) 30 O2 consumption and CO2 production decr by 50% Incr myocardial irritability, ectopics; threshold for spontaneous bad arrhythmidefibrillation and antiarrhythmics become ineffective Double intervals between drug doses 29 Pupils dilated VF may occur 28 HR 30-40 Rigidity BMR decr by 55-65%; major acidosis 26 Areflexia 25 Risk of asystole; CO 45% normal Cerebral blood flow 1/3 normal 24 Loss of vascular tone and cerebrovascular autoregulation 23 Absent corneal and oculocephalic reflex 22 Max risk of VF 20 HR 20 19 EEG flat, appears dead 18 Asystole

  18. What did Auckland ED do? • Filled out a risk pro

  19. Meanwhile Jack had a cardiac arrest…

  20. What should Auckland ED do?

  21. What should Auckland ED do? • Assess breathing and pulse for up to 1min to confirm • A+B: increased risk of gastric stasis • C: • T <30: most drugs / defib / pacing ineffective until… • T 30-35: give but double intervals between doses • Can try single shock + initial drugs for VF/VT, but then wait until >30 degrees • Warm IVF resus (42 degree 5% dextrose at 200ml/hr); will need large volumes • Only pace bradycardia if persists after warming

  22. Pharmacology • Most drug activity temperature dependent • Toxic doses required for effect • Leading to problems when rewarmed • Most arrhythmias revert with rewarming • VF treatment controversial • Bretylium

  23. Jack was made warm… • Rapidly rewarm to 30-34 degrees then slow • Passive rewarming • If mild; give the dude a blanket • Active external • If moderate / not shivering / CV compromise • Bair hugger, heat back etc… • Active internal • If severe • Humidified O2, blood warmer, lavages, haemodialysis, ECMO

  24. Rewarming research in general • Paucity of RCTs esp in humans • Volunteer studies predominate, usually in shivering mild hypothermics • Methodological variations with same Rx • Questionable external validity • Limited clinical trials with small numbers • Many therapies ethically hard to study

  25. Scoring Systems on Hospital Arrival The simple approach Modell & Conn 1984 – in ED within 1 hr of rescue (paeds) Asymptomatic Symptomatic Critical Obviously dead

  26. Luckily for Jack… • Rapid onset hypothermia and being young has better chance of survival Here he is pictured with his discharge summary and the SMO On Call (Bernard?)

  27. As Jack was leaving Auckland ED… • He went to the toilet, washed his hands as his mother had taught him, and was electrocuted by the hand dryer (don’t ask me how). • He was found by a patient with a sore toe.

  28. Jack was frazzled. • How frazzled depends on: • Voltage: high risk if >600V • Household voltage is 240V; lightening is >100 million V • Current type • Household is AC; lightening is DC • Current size • mAmps; >10mAmp  paralysis + tetany • Resistance • Bone > fat > tendon > skin > muscle > BV’s > nerve • Pathway • Vertical = bad for brain; 20% mortality • Horizonal = bad for heart + lungs; 60% mortality; 3x incr risk of VF • If ground current, more severe injury if legs apart • Duration • AC = longer (0.3-2secs) due to tetany • DC = shorter (millisecs) as thrown away

  29. AC vs DC • AC • Deep tissue damage • More likely to need fasciotomy / have rhabdo • 10% severe burns get ARF • Aim UO 1-2ml/kg/hr or use Parkland formula • Causes tetany prolonged apnoea (even after ROSC) • Causes VF (may cause asystole if high voltage) • DC • Superficial tissue damage (lightening can cause “flashover”) • Severe burns can be caused by high voltage arcs • BUT causes asystole • Cardiac arrest in 75% direct lightening strike injuries • Lightening strike mortality rate 10-30% (2/3 in 1st hour due to apnoea / arrhythmia); good prognosis unless significant 2Y injury • Blast injury (always look for TM rupture, hollow viscera) • Blunt trauma (high risk spinal #)

  30. Lightening • Look for entry and exit wounds • Do not signify depth • Skin • Cutaneous findings in 90% • Lichtenburg figures (extravasation of blood in subcutaneous tissue) • Look for clothing injury • Keraunoparalysis • Delayed onset transient paralysis + sensory disturbance + peripheral vasoconstriction • Always examine the eyes • Corneal burns, intraocular haemorrhage, retinal detachment, hyphema; late onset cataracts common • All require opthalmology review • Dilated pupils don’t mean they’re dead • Always examine the ears • 50% have TM rupture; sensorineural hearing loss

  31. This is not Jack

  32. What did Auckland ED do? • Filled out a risk pro

  33. Yes, and what else? • Jack seemed alright. • What did Auckland ED do with him?

  34. To monitor or not to monitor? • Do initial ECG • Monitoring is NOT indicated if asymptomatic and initial ECG normal • Indications for ECG monitoring (at least 12hrs) • High voltage injury (>1000V) • Abnormal ECG • LOC / seizures • Previous cardiac disease • Burns

  35. To admit or not to admit? • Discharge if: • 240V or less • Brief • No LOC / tetany / burns • Normal exam and asymptomatic • Normal ECG • Do urine (for myoglobin) and ECG if: • Minor wound / paraesthesia • Admit if: • >600V • Abnormal ECG or examination • Horizontal transmission

  36. Jack was OK. • Jack had a normal ECG and examination. He felt great. Jack was discharged home. Here he is, pictured with his discharge summary (Bernard had finished his shift).

  37. Jack wandered home. • He took a ferry to Waiheke, where he lived with some twits. Guess what happened next…

  38. No he wasn’t envenomated. We’re not covering that cos we’re not bloody Australian.

  39. Jack almost drowned. • He was found by a middle aged hippy. • He is choppered into Auckland ED. The noisy R40 tells us his GCS is 6 and the RTA is 10 minutes.

  40. From Auerbach: Wilderness Medicine, 5th ed. ( Submersion or near-drowning) Fig 68.4.

  41. Cardiovascular Effects • Hypotension • Shock, acidosis, hypovolemia (natriuresis), autonomic instability • Arrhythmias • Asystole (55%), • Ventricular tachycardia/fibrillation (29%) • Bradycardia (16%) • Brugada • Long-QT syndromes

  42. What should Auckland ED do?

  43. Wait… • It is the helicopter after all. • Pictured below is the resus team with Les Galler.

  44. Drowning Resus • C: C spine immobilisation if • History of diving, use of water slide, MVA, signs of injury, ETOH • A+B: aggressive respiratory resus • Intubate if • Requiring FiO2 >40-60% to attain PO2 >70 • Use PSV starting at 10cm, PEEP 5-7.5cm; wean ASAP to prevent barotrauma • C • N saline IVF resus (but beware puloedema) • Monitor electrolytes • Do 1hr CPR if persistent apnoea and asystole • D • Trt seizures; maintain normoG; rewarm if needed

  45. Ventilation Most text books will support a trial of NIV if blood pressure and GCS appropriate, however there are no literature to support its use Start low and titrate up volume support Vt low – 6mls/kg PEEP 5-10 cm H20 only if PaO2 < 60 on FiO2 <0.6 Ventilate for 24 hours to allow regeneration of surfactant

  46. A note on rewarming… • Consider induced hypothermia • If comatose with spontaneous circulation • Do not actively warm to >32-34 • Aim T 32-34 ASAP and maintain for 12-24hrs Vandenet al. Part 12: cardiac arrest in special situations: drowning:2010 American Heart AssociationGuidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010;122:Suppl 3:S847-8 Guenether U et al.Extendedtheraeutic hypothermia for several days during extra-corporeal membrane-oxygenation after drowning and cardiac arrest: two cases of survival with no neurological sequelae. Resuscitation 2009;80:379-81 WARNER et al. Recommendations and consensus brain resuscitation in the drowning victim. Bierens JJLM, ed. Handbook on drowning: prevention, rescue and treatment. Berlin: Springer-Verlag, 2006:436-9

  47. Asymptomatic patient No comorbidities If at 4 - 6 hours: CXR, ABG normal Normal vitals on air Remain ASx = discharge with advice

  48. Symptomatic Patient Consider foreign material in airway (approx. 50% of surf submersions) Salbutamol / Ipratoprium nebs for bronchospasm NG placement on free drainage may improve ventilatory distress High risk for vomiting and gastric content aspiration Suction +++ Most will require fluid resuscitation secondary to diuresis Beware hypothermia and trauma

  49. Does it matter that it was salt water? • Nah, not really • Electrolyte abnormalities are theoretical • Abx if features of infection develop • Broad spectrum if grossly contaminated water • Anti-pseudomonal if in spa • Chemical pneumonitis if swimming pool • Sand pneumonitis if salt water • Fram neg, anaerobes, staph, fungi, algae, protozoa, aeromonas if freshwater)

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