Download
slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
Accidental Hypothermia PowerPoint Presentation
Download Presentation
Accidental Hypothermia

Accidental Hypothermia

351 Views Download Presentation
Download Presentation

Accidental Hypothermia

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

    1. Accidental Hypothermia Franois 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 analysisor it doesnt matter? 2) ..as hes asking the question your are asking yourselfwhat the is afterdrop?2) ..as hes asking the question your are asking yourselfwhat 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 50s to late 70s 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 50s to late 70s 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 < 35though you will read in the ACLS (and its the only place), it is < 36 degrees. I havent seen one single article where they define hypothermia as < 36 in there methodologyI 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 < 35though you will read in the ACLS (and its the only place), it is < 36 degrees. I havent seen one single article where they define hypothermia as < 36 in there methodologyI 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 circuitswell 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 dont have the time for thishowever 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 circuitswell 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 dont 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 guywithout the breatheSo the clinical presentation for mild hypothermia More or less like a drunk guywithout the breathe

    17. Moderate (28 32?C) Stupor No shivering Bradycardic / A.fib ? BP ? RR Pupils dilated (< 30?C) - dont forget if pt tachycardicthink secondary cause- dont forget if pt tachycardicthink 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 20s who survived neurologically intact. 1 case: 13.5 (peds). Thats why many people claims that you are not dead until warm and deadmultiple case reports of patients with temperature in low 20s who survived neurologically intact. 1 case: 13.5 (peds). Thats 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 signsyou get an ECG (!)- and before you get any vital signsyou 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 50s. 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-depolarizationV3-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) Dont warm it : 30?C B) Warm it to 37?C C) heu(30+37)/2.33.5?C D) Both and Ill pick the best one. Acidotic? Ventilator settings? So what will you tell him? dont warm itrun it at 30 degrees. So you finally choose DAcidotic? Ventilator settings? So what will you tell him? dont warm itrun 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 ? Everythings perfect, I dont 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 cant provide you all the details, but this is just normal physiologic responseFor 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 cant 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 curve1st 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 Lets talk about the rewarming methodsso 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)Lets talk about the rewarming methodsso 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. Concerncausing vasodilatation and transport of colder peripheral blood to corewell talk about it later. Concerncausing vasodilatation and transport of colder peripheral blood to corewell 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 oneFirst 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 patientsand 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 patientsand 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 studiesHeating 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 SalineNot 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 cant metabolise lactate Corn syprup.RL: hypothermic liver cant 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 lavage Closed-thoracic lavage Continuous 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 minTemp=33 2nd case: 36 y.o, 25 degrees, sameTemp 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 minTemp=33 2nd case: 36 y.o, 25 degrees, sameTemp 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 stufffor 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 dont have access ot extracorporal rewarming techniques, this is probably your best choice(in cardiac arrest!)Now we fall into the more esoteric stufffor 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 dont 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 dont want to spend too much time on thisand I just want to say: Good evidences of efficacy of these methods Actually the most effective rewarming techniquesdont want to spend too much time on thisand 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 pts 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: pts BPnot Veno-venous CPBprovides flow but the heparin needed might be a problem. Heparin-bonded tubing may overcome this problemHD : good if renal dysfnt AV: pts BPnot Veno-venous CPBprovides 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 didnt think it was worth it to go into the details of the paper Im just mentionning it because we might hear about it in the futurethe best evidence we have I didnt think it was worth it to go into the details of the paper Im 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 80s 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 heartas much as thought before. Correlated by many other papers Therefore, active external rewarming does not increase threat of further cooling of the heartas 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 heartas 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 Baycontest 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 mentionI was myself shocked when I saw that papernot as much by the study as by the contest !- I thought it was interesting to mentionI was myself shocked when I saw that papernot 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 Vasodilatationlow BP So there are other pitfalls to external rewarming than the drop in temperatureIn 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 Vasodilatationlow 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?Hes in the top 3 god of accidental hypothermiabut 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?Hes in the top 3 god of accidental hypothermiabut 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: were talking obviously of V.fibaccumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: were 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: were talking obviously of V.fibaccumulates to toxic levels If you want to give Rx (below 30), be VERY CAREFUL Shocks: were 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 bestand 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, anddont 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, anddont forget,

    75. Play carefully