Accidental Hypothermia

1. Accidental Hypothermia Fran�ois Dufresne McGill Emergency Medicine May 2nd 2001

2. The Case of Tommy 23h10 Call from MD working in James Bay Male, 27 y.o. Unresponsive. Found in snow, cross-country skiing Normal Airway. Breathing. ? O2 sat. Femoral pulse + (35) ? BP. GCS=3 TR? = 28?C. IV. Monitor. Mask with 100% O2

3. The Case of Tommy� Friend told MD: ? PMH. ? Rx. ? drugs. ? EtOH Major foot deformity Looks like fell in ski and could not return home by himself� MD has some questions for you� -though he is used treating minor cold-related injury, this case is much heavier and he has some questions for you�-though he is used treating minor cold-related injury, this case is much heavier and he has some questions for you�

4. The Case of Tommy� Should he intubate? Are there risks to precipitate dysrythmias? Cold myocardium prone to arythmias? How should he rewarm the patient? Danger of afterdrop? He wants an ABG but should he ask for the blood to be warmed to normal T? for analysis�or it doesn�t matter? 2) ..as he�s asking the question your are asking yourself�what the �is ��afterdrop��?2) ..as he�s asking the question your are asking yourself�what the �is ��afterdrop��?

5. The Case of Tommy� MD calls you back 30 minutes later Pt in cardiac arrest : V.fib. Now 27?C 3 shocks Epinephrine + re-shock Having Amiodarone prepared� How long should he do CPR and rescussitation? How long rescussitation?�20 minutes of CPR� So those are some of the questions I will try to answer during this presentation.How long rescussitation?�20 minutes of CPR� So those are some of the questions I will try to answer during this presentation.

6. Introduction EtOH ? Mental illness ? Homelessness ? Province of Quebec ? Cold Closer to us, as there is more and more alcoolism, mental illnesses and homelessness, the number of ED encounters with hypothermia is growing. Moreover, in this cold environnement of Quebec, we are particularly more likely to see cases of hypothermia. As emergentologists, we are the one who are faced with this problem and no other specialities should be more prepared than us to deal with this problem. Hypothermia is part of the environmental emergencies that we should be comfortable to manage.Closer to us, as there is more and more alcoolism, mental illnesses and homelessness, the number of ED encounters with hypothermia is growing. Moreover, in this cold environnement of Quebec, we are particularly more likely to see cases of hypothermia. As emergentologists, we are the one who are faced with this problem and no other specialities should be more prepared than us to deal with this problem. Hypothermia is part of the environmental emergencies that we should be comfortable to manage.

7. Plan Definitions Physiology Pathophysiology Labs findings : ABG, ECG Rewarming methods Afterdrop ACLS 2000 guidelines - So during this presentation, we will go through some definitions, quickly through physiology and pathophysiology to spend more time on some lab findings particularly blood gases and ECG and the rewarming methods as well on the afterdop phenomenon. We will finish by summurazing the new ACLS 2000 guidelines on hypothermia.- So during this presentation, we will go through some definitions, quickly through physiology and pathophysiology to spend more time on some lab findings particularly blood gases and ECG and the rewarming methods as well on the afterdop phenomenon. We will finish by summurazing the new ACLS 2000 guidelines on hypothermia.

8. Definitions Primary VS Secondary Primary Normal thermoregulation Overwhelming cold exposure Secondary Abnormal thermogenesis Multiple causes Primary hypothermia happens because of overwhelming cold exposure. Heat production in itself is normal. There are multiple causes of secondary hypothermia : hypothyroidism, burns, hypothalamic abnormalities, sepsis, etc. Look in textbooks and you will find 40-50 differents causes. This talk,though, will focus on the primary, accidental hypothermia So I reviewed accidental, primary hypothermia And I can tell you that there are hundreds of studies on hypothermia (+++ references!). Rosen has 350 references and most of the good review articles has anywhere from 200-500 references(!). However 90%: animals (pigs, dogs), in O.R., induced-hypothermia and most are retrospective. Also, studies from late �50�s to late �70�s a lot ! I tried to gather what was more relevant to the ED.Primary hypothermia happens because of overwhelming cold exposure. Heat production in itself is normal. There are multiple causes of secondary hypothermia : hypothyroidism, burns, hypothalamic abnormalities, sepsis, etc. Look in textbooks and you will find 40-50 differents causes. This talk,though, will focus on the primary, accidental hypothermia So I reviewed accidental, primary hypothermia And I can tell you that there are hundreds of studies on hypothermia (+++ references!). Rosen has 350 references and most of the good review articles has anywhere from 200-500 references(!). However 90%: animals (pigs, dogs), in O.R., induced-hypothermia and most are retrospective. Also, studies from late �50�s to late �70�s a lot ! I tried to gather what was more relevant to the ED.

9. Definitions Hypothermia : < 35?C Mild : 32-35?C Moderate : 28-32?C Severe : < 28?C hypothermia < 35�though you will read in the ACLS (and it�s the only place), it is < 36 degrees. I haven�t seen one single article where they define hypothermia as < 36 in there methodology�I just wanted to mention it. There is a little bit of variability in these definitions depending on where you read� (Severe : 20-28?C) (Profound : 14-20?C) (Deep : < 14?C) hypothermia < 35�though you will read in the ACLS (and it�s the only place), it is < 36 degrees. I haven�t seen one single article where they define hypothermia as < 36 in there methodology�I just wanted to mention it. There is a little bit of variability in these definitions depending on where you read� (Severe : 20-28?C) (Profound : 14-20?C) (Deep : < 14?C)

10. Physiology: Heat production Basal metabolism (Metabolic rate) Heart / Liver Anterior hypothalamus Thyroid / Sympathetic Preshivering muscle tone (2x) Shivering (2-5x) Posterior hypothalamus Normal temperature is a balances between heat production and dissipation. Heat production is done through� Metabolic activity of heart and liver especially anterior hypothalamus regulates the nonshivering heat conservation and dissipation. Sympathetic : vasoconstriction Social response to cold (wear more clothes, move to warmer environement�)Normal temperature is a balances between heat production and dissipation. Heat production is done through� Metabolic activity of heart and liver especially anterior hypothalamus regulates the nonshivering heat conservation and dissipation. Sympathetic : vasoconstriction Social response to cold (wear more clothes, move to warmer environement�)

11. Physiology: Heat dissipation Radiation (55-65%) Gradient between environement and exposed body area. Conduction (2-3%) Direct contact with cold substance Convection (10-15%) Wind� Evaporation (20-35%) Radiation which accounts for � conduction X5 in wet clothing and up to 25X in cold water. Evaporation: mainly through breathing Radiation which accounts for � conduction X5 in wet clothing and up to 25X in cold water. Evaporation: mainly through breathing

12. Physiology� Above 32?C: Vasoconstriction Shivering Basal metabolic rate Below 32?C: No shivering Below 24?C: No basal metabolic rate -Human studies on shivering in Annals of EM, 1987�-Human studies on shivering in Annals of EM, 1987�

13. Pathophysiology Cardiovascular Initial tachycardia Gradual bradycardia : HR? 50% at 28?C. Not consistent ? Hypoglycemia, intoxication, hypovolemia,�? Refractory to atropine ? BP ? CI A.fib (T? < 32?C) V.fib (T? < 28?C) as you know, hypothermia has many effects on the different systems and organs. Because this is something you can all read in textbooks and because it could be an entire whole presentation in itself, I will go briefly through these effects. Not consistent: sepsis, � (hypothermia: depression of spontaneaous depolariz. of pacemaker cells: decrease in fibrillation threshold) as you know, hypothermia has many effects on the different systems and organs. Because this is something you can all read in textbooks and because it could be an entire whole presentation in itself, I will go briefly through these effects. Not consistent: sepsis, � (hypothermia: depression of spontaneaous depolariz. of pacemaker cells: decrease in fibrillation threshold)

14. Pathophysiology� CNS Cerebral metabolism ? 6% / 1?C Normal autoregulation until 25?C EEG flat at 19?C Renal Cold diuresis Peripheral vasoconstriction Failure to reabsorb Na+ and water. - per 1 degree decline in temperature.- per 1 degree decline in temperature.

15. Pathophysiology� Respiratory CO2 production ? 50% at 30?C Decreased RR ARDS possible Hematology Hemostasis and coagulation impaired Problems with CPB however in severe hypothermia, normal resp.control is altered and CO2 retention can occur. Platelets dysfunction. Von Willebrand factor nearly abolished. CPB: cardiopulmonary bypass where there often need to use heparin in the circuits�we�ll come back to that� And you could add to this the increase in drug elimination time as liver function is depressed. We could also get into the details of the shift of the oxyhemoglobin dissociation curve to the left and so on and so forth but we don�t have the time for this�however in severe hypothermia, normal resp.control is altered and CO2 retention can occur. Platelets dysfunction. Von Willebrand factor nearly abolished. CPB: cardiopulmonary bypass where there often need to use heparin in the circuits�we�ll come back to that� And you could add to this the increase in drug elimination time as liver function is depressed. We could also get into the details of the shift of the oxyhemoglobin dissociation curve to the left and so on and so forth but we don�t have the time for this�

16. Mild (> 32?C) Increase metabolic rate Maximum shivering thermogenesis Amnesia / dysarthria / ataxia Loss of coordination Tachycardic, tachypneic Normal BP So the clinical presentation for mild hypothermia� More or less like a drunk guy�without the breathe�So the clinical presentation for mild hypothermia� More or less like a drunk guy�without the breathe�

17. Moderate (28� 32?C) Stupor No shivering Bradycardic / A.fib ? BP ? RR Pupils dilated (< 30?C) - don�t forget if pt tachycardic�think secondary cause�- don�t forget if pt tachycardic�think secondary cause�

18. Severe (<28?C ) Coma No corneal or oculocephalic reflexes ?? BP V.fib (Maximum risk: 22?C) Apnea Asystole Areflexia / fixed pupils Flat EEG (19?C) multiple case reports of patients with temperature in low 20�s who survived neurologically intact. 1 case: 13.5 (peds). That�s why many people claims that you are not dead until warm and dead�multiple case reports of patients with temperature in low 20�s who survived neurologically intact. 1 case: 13.5 (peds). That�s why many people claims that you are not dead until warm and dead�

19. Lab findings : ECG Woman, 75 y.o Found unconscious in her apartment - �and before you get any vital signs�you get an ECG (!)- �and before you get any vital signs�you get an ECG (!)

20. - you can see those abnormal waves�- you can see those abnormal waves�

21. - and those are called�.- and those are called�.

22. Osborn (J) Wave Mr. John J. Osborn in the early �50�s. When T?< 33?C 25%-30% of patients Positive-negative deflection - in honor of Mr. �- in honor of Mr. �

23. Osborne (J) Wave� Amplitude proportionnal to degree of hypothermia Usually V3-V6 At junction of QRS and ST segment V3-V6 and sometimes in the inferior leads� they are thought to be abnormal repolarization or abnormal end-depolarization�V3-V6 and sometimes in the inferior leads� they are thought to be abnormal repolarization or abnormal end-depolarization�

24. ECG in Hypothermia Muscle tremors artifacts Early changes Bradycardia T wave inversion Prolonged PR, QRS and QT intervals A.fib when T? < 32?C V.fib when T? < 28?C -other changes on the ECG that you might find in hypothermia�-other changes on the ECG that you might find in hypothermia�

25. Lab findings : ABG Man, 45 y.o,. Rectal T?= 30?C. ?LOC Intubated. Acid-base status? Technician asks you if he should warm the blood before analysis� A) Don�t warm it : 30?C B) Warm it to 37?C C) heu�(30+37)/2�.33.5?C D) Both and I�ll pick the best one. Acidotic? Ventilator settings? So what will you tell him? �don�t warm it�run it at 30 degrees. So you finally choose D�Acidotic? Ventilator settings? So what will you tell him? �don�t warm it�run it at 30 degrees. So you finally choose D�

26. ABG in Hypothermia 1st ABG (30?C): pH = 7.5 pCO2 = 27 2nd ABG (37?C): pH = 7.4 pCO2 = 40 Which one do you pick? Will you try to ? RR or ?VT to ? pCO2 ? Everything�s perfect, I don�t touch the ventilator ? The answer ? �.

27. ABG in Hypothermia��the rationale pH of water at any given T? defines neutrality H2O ? H+ + OH- As T?? , less free H+ and OH- are generated and pH of neutrality? . As T?? , CO2 content is the same but pCO2 ?. For a very complete biochemestry lesson, read this article by Delaney� Hydrogen and hydroxyl ions At Temp=25, H+=1x10(-7)�pH=-log(base10) of 10(-7)=7. At Temp=37, H+=1.6x10(-7)�pH=6.8 HCO3- + H+ --? H2CO3 -? H2O + CO2 I can�t provide you all the details, but this is just normal physiologic response�For a very complete biochemestry lesson, read this article by Delaney� Hydrogen and hydroxyl ions At Temp=25, H+=1x10(-7)�pH=-log(base10) of 10(-7)=7. At Temp=37, H+=1.6x10(-7)�pH=6.8 HCO3- + H+ --? H2CO3 -? H2O + CO2 I can�t provide you all the details, but this is just normal physiologic response�

29. So� 1st ABG (30?C): pH = 7.5 pCO2 = 27 2nd ABG (37?C): pH = 7.4 pCO2 = 40 1st is normal because if you were to plot it on the graph, you would see that it falls on the curve�1st is normal because if you were to plot it on the graph, you would see that it falls on the curve�

30. ABG in Hypothermia��the rationale ABG machines usually warms blood to 37?C. So use the UNCORRECTED ABG for normal T? .

31. Rewarming methods :Passive rewarming Endogenous heat production Shivering, metabolic rate, TSH, sympathetic,� Involves decreasing heat loss Remove from cold environnement Remove wet clothes Provide blanket Let�s talk about the rewarming methods�so there are three main methods: passive, active external, active internal� Passive: allows endogenous heat prodution to increase the core temperature. Mecanisms must be intact ! Decrease heat loss: provide blankets (warm vs not warm: no difference) (more than one blanket does not make difference)Let�s talk about the rewarming methods�so there are three main methods: passive, active external, active internal� Passive: allows endogenous heat prodution to increase the core temperature. Mecanisms must be intact ! Decrease heat loss: provide blankets (warm vs not warm: no difference) (more than one blanket does not make difference)

32. Passive rewarming� O2 consumption can? > 90% CO2 production can? by 65% Possible anaerobic metabolism Rewarming rate : 0.5?C - 2.0?C /h Method of choice for mild hypothermia Adjunt for moderate hypothermia With intact thermoregulation, oxygen� Anaerobic: lactic acidosis, cardiopulmonary stress So passive rewarming ALONE should not be used for SEVERE hypothermia probably more around 1 degree /h With intact thermoregulation, oxygen� Anaerobic: lactic acidosis, cardiopulmonary stress So passive rewarming ALONE should not be used for SEVERE hypothermia probably more around 1 degree /h

33. Rewarming methods :Active external rewarming Heat to body surfaces Heating blankets (fluid filled) Air blankets Radiant warmers Immersion in hot bath Water bottles / Heating pads Less effective than internal rewarming if vasoconstricted +++ Transfert of exogenous heat to patient. Hot bath: might be the most effective but: no monitor, no defibrillation, vasodilatation+++ (low BP?). works better for EtOH who are vasodilatedTransfert of exogenous heat to patient. Hot bath: might be the most effective but: no monitor, no defibrillation, vasodilatation+++ (low BP?). works better for EtOH who are vasodilated

34. Active external rewarming� Concern about afterdrop. Rewarming rates : 1?C � 2.5?C / h Circulatory problem may be ? by applying devices to trunk only. Very few prospective controlled study comparing methods. Concern�causing vasodilatation and transport of colder peripheral blood to core�we�ll talk about it later. Concern�causing vasodilatation and transport of colder peripheral blood to core�we�ll talk about it later.

35. Forced Air Blankets ED patients Moderate to severe hypothermia (< 32?C) Exclusion criteria Cardiac arrest Hypothalamic lesions 16 patients Randomized to passive insulation with cotton blanket or forced air blanket @ 43?C . First controlled study comparing rewarming methods in moderate to severe hypothermia. (show physical example of blanket!) Disposible Plastic / Paper covers 16 patients! when I tell you there is very few prospective controlled study, this is one of the best one�First controlled study comparing rewarming methods in moderate to severe hypothermia. (show physical example of blanket!) Disposible Plastic / Paper covers 16 patients! when I tell you there is very few prospective controlled study, this is one of the best one�

36. Forced Air Blanket� All patients: warm iv fluids @ 38?C Warm O2 (40?C) End point: T = 35?C Looked at: Rates of rewarming Skin damage by blankets Wet cloths removed. (Intubation PRN) Head/Neck wrapped with warmed blanketsWet cloths removed. (Intubation PRN) Head/Neck wrapped with warmed blankets

37. Forced Air Blanket� Results No afterdrop in both groups No skin erythema/damage Rewarming rates (p=0.01) Forced-Air: 2.4?C / h Regular blanket: 1.4?C / h Similar group: age, sex, admission temp, GCS, fluid volume, U/OSimilar group: age, sex, admission temp, GCS, fluid volume, U/O

39. Electrical heating blanket Carbon fiber-resistive blanket VS Passive rewarming 8 patients Induced-hypothermia (33?C) Skin thermal flux transducer CO2 concentration production through mask Compared: rates of rewarming core heat content Recent study in Annals (2000) looked at electical heating through carbon fiber-resistive blanket VS reflective metallic-foil blanket � 8 patients�and I am presenting you the best evidences� Induced-hypothermia: general anesthesiaRecent study in Annals (2000) looked at electical heating through carbon fiber-resistive blanket VS reflective metallic-foil blanket � 8 patients�and I am presenting you the best evidences� Induced-hypothermia: general anesthesia

40. Electrical heating Results Core heat content >> electrical heating Rates ? 1.5?C/h > with electical heating No afterdrop both groups Heating blanket, fluid filled (alcool)�.are also used but less and less because of burns�(show the blanket!) So prospective studies on hypothermia are small studies�Heating blanket, fluid filled (alcool)�.are also used but less and less because of burns�(show the blanket!) So prospective studies on hypothermia are small studies�

41. Rewarming methods :Active internal (core) rewarming Warm iv fluids Warm, humid oxygen Peritoneal lavage Gastric / Esophageal lavage Bladder / Rectal lavage Pleural / Mediastinal lavage Microwaves (Diathermy) Extracorporeal circulatory rewarming - there are many rewarming technics for core rewarming..that is�- there are many rewarming technics for core rewarming..that is�

42. Warm iv fluids Up to 45?C shown to be safe 65?C fluid studied in dogs Journal of Trauma 1993 (8 dogs) American Journal of Surgery 1996 (10 dogs) Through IVC Safe. No Complications 2.9?C/h compared to 1.25?C/h (J Trauma) 3.7?C/h compared to 1.75?C/h (Am J Surg)

43. Warm iv fluids� Saline�Not RL Long tubulure = lost of heat Can use microwave for saline (No D5W) Annals of EM, 1984 and 1985 1L of NS to 39?C : 2 minutes at high power. No microwave rewarming for PRBC Hemolysis Hemoglobinuria Transfusion reaction RL: hypothermic liver can�t metabolise lactate Corn syprup.RL: hypothermic liver can�t metabolise lactate Corn syprup.

44. Warm, humidified O2 42?C-46?C Prevent heat loss Negligible heat gain Very important in management of hypothermic patient: Up to 30% of heat production lost through airway. -negligible heat gain : multiple studies correlate it.-negligible heat gain : multiple studies correlate it.

45. Gastric/Oesophageal/ Bladder/Rectal lavage Not shown to be better than external rewarming. Limited surface area Limited heat exchange Limited utility (!) Recommend as last resort when other modalities not available. - no mention in ACLS 2000- no mention in ACLS 2000

46. Peritoneal lavage Fluid at 40-45?C Up to 12 L/h KCl free Hepatic rewarming Renal support when dialysate is used 2?C-4?C / h C.I. Abdominal trauma Acute abdomen Free intra-abdominal air Most widely recognized method for patients not in cardiac arrest and that are severly hypothermic� Most widely recognized method for patients not in cardiac arrest and that are severly hypothermic�

47. Peritoneal lavage� Almost all studies before 1980 Almost all animal studies Critical Care Medicine 1988 11 dogs Comparing peritoneal/pleural lavage and heated aerosol inhalation Peritoneal and pleural lavage equivalent ? 6?C/h/m2 Heated inhalation alone : little heat gain

48. Pleural lavageClosed-thoracic lavageContinuous thoracic cavity lavage Two large (38F) ipsilateral chest tubes 1: 2nd or 3rd anterior intercostal space, midclavicular. 2: 5th or 6th intercostal space, posterior axillary line. NS or tap water @ 42?C Rewarms heart + greater vessels to allow continuous irrigation NS or tap water through anterior tube and passively drains through posterior tube. Limited clinical use: case reports: Annals of EM 1990 reports 2 cases 1st case: 70 y.o, 26 degrees, not in cardiac arrest, 40L over 20 min�Temp=33 2nd case: 36 y.o, 25 degrees, same�Temp 32to allow continuous irrigation NS or tap water through anterior tube and passively drains through posterior tube. Limited clinical use: case reports: Annals of EM 1990 reports 2 cases 1st case: 70 y.o, 26 degrees, not in cardiac arrest, 40L over 20 min�Temp=33 2nd case: 36 y.o, 25 degrees, same�Temp 32

49. Mediastinal lavage Requires certain expertise Limited clinical experience Case reports Internal cardiac massage 8?C / h Now we fall into the more esoteric stuff�for patients in cardiac arrest usually� Actually, most of the patient with Temp < 28 that you will see will be in cardiac arrest� Case reports of prolonged hypothermia with good outcome when mediastinal lavage used. Retrospective case review of 11 patients treated with thoracotomy, internal cardiac massage and warm mediastinal irrigation in Am J Emerg Med 2000 where 5 survived. If you don�t have access ot extracorporal rewarming techniques, this is probably your best choice(in cardiac arrest!)Now we fall into the more esoteric stuff�for patients in cardiac arrest usually� Actually, most of the patient with Temp < 28 that you will see will be in cardiac arrest� Case reports of prolonged hypothermia with good outcome when mediastinal lavage used. Retrospective case review of 11 patients treated with thoracotomy, internal cardiac massage and warm mediastinal irrigation in Am J Emerg Med 2000 where 5 survived. If you don�t have access ot extracorporal rewarming techniques, this is probably your best choice(in cardiac arrest!)

50. Extracorporeal blood rewarming techniques Hemodialysis Arteriovenous rewarming Venovenous rewarming Cardiopulmonary bypass don�t want to spend too much time on this�and I just want to say: Good evidences of efficacy of these methods Actually the most effective rewarming techniquesdon�t want to spend too much time on this�and I just want to say: Good evidences of efficacy of these methods Actually the most effective rewarming techniques

51. Extracorporeal blood rewarming� Hemodialysis : renal dysfunction AV depends on the pt�s BP CPB is the ��Gold Standard��. CPB improves long term survival and neurologic outcome. 15 of 32 long term survivors and none had neurologic deficits (7 years later). HD : good if renal dysfnt AV: pt�s BP�not Veno-venous� CPB�provides flow but the heparin needed might be a problem. Heparin-bonded tubing may overcome this problemHD : good if renal dysfnt AV: pt�s BP�not Veno-venous� CPB�provides flow but the heparin needed might be a problem. Heparin-bonded tubing may overcome this problem

52. Diathermy Ultrasonic waves Microwaves Short waves Few studies Radio wave regional hyperthermia: Experience with Tx of tumors. Not widespread because of dosages in human poorly defined.

53. Diathermy� Prospective Radio Wave vs. Peritoneal lavage 6 dogs Rate of rewarming 3x > for Radio wave. the best evidence we have� I didn�t think it was worth it to go into the details of the paper� I�m just mentionning it because we might hear about it in the future�the best evidence we have� I didn�t think it was worth it to go into the details of the paper� I�m just mentionning it because we might hear about it in the future�

54. The Afterdrop Phenomenon Continued fall in deep core T? during the initial period of rewarming. First described by James Currie in 1798 Theory of Burton and Edholm (1955): Attributed to peripheral vasodilatation Return of cold blood to central circulation Cooling of myocardium Accepted theory until mid �80�s All started when they observed that patient would deteriorate at the begginning of the rewarming phase or would crash going into ventricular arythmias and dying sometimes� They started measuring Temp and realised it was falling initially despite rewarming It was suggested that rapid external rewarming may exaggerate this afterdrop.All started when they observed that patient would deteriorate at the begginning of the rewarming phase or would crash going into ventricular arythmias and dying sometimes� They started measuring Temp and realised it was falling initially despite rewarming It was suggested that rapid external rewarming may exaggerate this afterdrop.

55. Paul Webb,An alternative explanation.J. Appl. Physiol. 1986 Fall of T? during active rewarming: Up to 2?C 10 � 30 min Used calorimeter, rectal, esophageal and tympanic probes. Heat loss calculation another theory which was confirmed many times afterwards. Multiple tables / graphics A very complex articleanother theory which was confirmed many times afterwards. Multiple tables / graphics A very complex article

56. 2 mecanisms for afterdrop Convection mecanism Return of cold blood from periphery Minimal is any contribution Conduction mecanism Thermal gradient principal Heat flow principal Condution of heat down a thermal gradient from a relatively warm core (blood) to a cold periphery (tissues). (Cool fast VS cool slow experience) Condution of heat down a thermal gradient from a relatively warm core (blood) to a cold periphery (tissues). (Cool fast VS cool slow experience)

57. Conduction Mecanism

58. Afterdrop: an alternative explanation Active external rewarming ? increase threat of further cooling of the heart�as much as thought before. Correlated by many other papers Therefore, active external rewarming does not increase threat of further cooling of the heart�as much as thought before. they compared patients with active external vs. Passive and they both had decrease in temp. Of the same magnitude. Therefore, active external rewarming does not increase threat of further cooling of the heart�as much as thought before. they compared patients with active external vs. Passive and they both had decrease in temp. Of the same magnitude.

59. The Alcatraz/San Francisco Swim Study San Francisco Bay�contest� Swims from Alcatraz Island to shore No wetsuits or protective clothing Water T? = 12?C (53?F) Outside : T? = 10?C 3 Km 11 subjects for study 23 y.o to 70 y.o (!) Measured T? after contest. - passive rewarming after contest.- passive rewarming after contest.

60. - I thought it was interesting to mention�I was myself shocked when I saw that paper�not as much by the study as by the contest !- I thought it was interesting to mention�I was myself shocked when I saw that paper�not as much by the study as by the contest !

61. Afterdrop conclusion Rectal T? lags behing esophageal T? and is often > than esophageal and pulmonary T?. Think about it but you can probably not prevent it. Issue with active external rewarming Other concerns about external rewarming: Acidosis Hypotension In conclusion for afterdrop, what comes out of all the studies is that� So whatever how hypothermic a patient is by rectal temperature, he is probably even more hypothermic! Washout of acidotic blood from periphery to core Vasodilatation�low BP� So there are other pitfalls to external rewarming than the drop in temperature�In conclusion for afterdrop, what comes out of all the studies is that� So whatever how hypothermic a patient is by rectal temperature, he is probably even more hypothermic! Washout of acidotic blood from periphery to core Vasodilatation�low BP� So there are other pitfalls to external rewarming than the drop in temperature�

62. Management: ED issues Intubation General belief it can induce arythmias Danzl, Multicenter Hypothermia Survey, Annals Emerg Med, Sept.87. Data from 13 ED 428 cases 117 intubation NO arythmias ABC of course but I want to talk about the more controverse issues. Intubation: well shown now that there is no increase in arrythmias Danzl�, seen this name somewhere before?�He�s in the top 3 god of accidental hypothermia�but where have you seen this name?�ABC of course but I want to talk about the more controverse issues. Intubation: well shown now that there is no increase in arrythmias Danzl�, seen this name somewhere before?�He�s in the top 3 god of accidental hypothermia�but where have you seen this name?�

63. Management: ED issues Bretylium Recommended for V.fib in hypothermia Removed from new ACLS 2000: ? availability and limited supply ? occurrence of side effects Still recommend in textbooks (Rosen) Recommended by US Wilderness Emergency Medical Services Institute Based on Dogs studies Good for prophylaxis only No point to present the studies but if you want the references, I can provide it to you� Based on few dogs� Animal studies and 2 human case reports.No point to present the studies but if you want the references, I can provide it to you� Based on few dogs� Animal studies and 2 human case reports.

64. Management: ED issues Drugs / Shocks NO drugs if T? < 30?C Not efficacious Not metabolised If > 30?C, ? intervals between doses If < 30?C and failure of 3 shocks accumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: we�re talking obviously of V.fib�accumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: we�re talking obviously of V.fib�

65. Management: ED issues Drugs / Shocks NO drugs if T? < 30?C Not efficacious Not metabolised If > 30?C, ? intervals between doses If < 30?C and failure of 3 shocks accumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: we�re talking obviously of V.fib�accumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: we�re talking obviously of V.fib�

66. ACLS 2000

67. This may require needle electrodes through the skinThis may require needle electrodes through the skin

69. 3) Methodes include: Radiant heat sources, warming beds, air-blanket, heating pads, hot water bottles.3) Methodes include: Radiant heat sources, warming beds, air-blanket, heating pads, hot water bottles.

70. 2) Should probably done only in-hospital2) Should probably done only in-hospital

71. 2) Probably should be done only in-hospital2) Probably should be done only in-hospital

74. Conclusion Hypothermia is rare but treatable Good outcome after prolonged arrests Include Hypothermia in your ? Dx Include T? as a 5th vital sign� Call early to organize CPB if available if patient in cardiac arrest Prevention is still the best�and� good outcome have been reported� Differential diagnosis because it can manifests by many different ways from tachy/bradycardia to a coagulopathy� 5th vital sign after HR, RR, BP, O2sat, � �and�don�t forget, �good outcome have been reported� Differential diagnosis because it can manifests by many different ways from tachy/bradycardia to a coagulopathy� 5th vital sign after HR, RR, BP, O2sat, � �and�don�t forget, �

75. Play carefully�