Part 10.4: Hypothermia 1V-137 of defibrillation attempts that should be made have not been with warmed fluids, pleural lavage with warm saline through established. But if ventricular tachycardia (VT)or VF chest tubes, extracorporeal blood warming with partial by present, defibrillation should be attempted. Automated exter- pass, 49, 12, 14. I5 and cardiopulmonary bypass. 16 nal defibrillators(AEDs)may be used for these patients. If During rewarming, patients who have been hypothermic vf is detected. it should be treated with I shock thel for >45 to 60 minutes are likely to require volume adminis- immediately followed by resumption of CPR, as outline tration because the vascular space expands with vasodilation. elsewhere in these guidelines for VF/VT(see Part 5: Elec- Routine administration of steroids, barbiturates, and antibiot- trical Therapies: Automated External Defibrillators, Defibril- ics has not been documented to increase survival rates or lation, Cardioversion, and Pacing"). If the patient does not decrease postresuscitation damage. 17, I8 respond to I shock, further defibrillation attempts should be If drowning preceded hypothermia, successful resuscita- deferred, and the rescuer should focus on continuing CPR and tion is unlikely. Because severe hypothermia is frequently rewarming the patient to a range of 30C to 32C(86 F to preceded by other disorders(eg, drug overdose, alcohol use, 89.6F) before repeating the defibrillation attempt. If core or trauma), the clinician must look for and treat these temperature is <30C (86%F), successful conversion to nor- underlying conditions while simultaneously treating the mal sinus rhythm may not be possible until rewarming is hyp To prevent further core heat loss, remove wet garments and Withholding and Cessation of protect the victim from further environmental exposure. Resuscitative efforts Insofar as possible this should be done while providing initial In the field resuscitation may be withheld if the victim has BLS therapies. Beyond these critical initial steps, the treat- obvious lethal injuries or if the body is frozen so that nose and ment of severe hypothermia(temperature <30C [86FD in mouth are blocked by ice and chest compression is the field remains controversial. Many providers do not have the time or equipment to assess core body temperature or to Some clinicians believe that patients who appear dead after institute aggressive rewarming techniques, although these prolonged exposure to cold temperatures should not be methods should be initiated when available. 49, 12,1 considered dead until they are warmed to near normal core temperature. 10,I1 Hypothermia may exert a protective effect Modifications to ACLS for Hypothermia on the brain and organs if the hypothermia develops rapidly For unresponsive patients or those in arrest, endotracheal in victims of cardiac arrest. When a victim of hypothermia is intubation is appropriate. Intubation serves 2 purposes in the discovered, however, it may be impossible to distinguish management of hypothermia: it enables provision of effective primary from secondary hypothermia. When it is clinically ventilation with warm, humidified oxygen, and it can isolate impossible to know whether the arrest or the hypothermia he airway to reduce the likelihood of aspiration. occurred first, rescuers should try to stabilize the patient with ACLS management of cardiac arrest due to hypothermia CPR. Basic maneuvers to limit heat loss and begin rewarming focuses on more aggressive active core rewarming techniques should be started. Once the patient is in the hospital, physi as the primary therapeutic modality. The hypothermic heart cians should use their clinical judgment to decide when may be unresponsive to cardiovascular drugs, pacemaker resuscitative efforts should cease in a victim of hypothermic stimulation, and defibrillation. In addition, drug metabolism is reduced. There is concern that in the severely hypothermic victim. cardioactive medications can accumulate to toxic References levels in the peripheral circulation if given repeatedly. For I. Holzer M. Behringer w, sc orkhuber W, Zeiner A, Sterz F, Laggner AN these reasons iv drugs are often withheld if the victims core Frass M, Siostrozonek P, Ratheiser K, Kaff A. Mild hypothermia and body temperature is <30C(86F). If the core body temper utcome after CPR. Hypothermia for Cardiac Arrest (HACA)Study ature is >30C, Iv medications may be administered but with rz F Safar P, Fisherman S, Radovsky A, Kuboyama K, Oku K. Mild increased intervals between doses ypothermic cardiopulmonary resuscitation impro As noted previously, a defibrillation attempt is appropriate longed cardiac arrest in dogs. Crir Care Med. 1991; 19: 379-389 if VF/VT is present. If the patient fails to respond to the initial 3. Farstad M, Andersen KS, Koller ME, Grong K, Segadal L, Husby P. defibrillation attempt or initial drug therapy, defer subsequent Rewarming from accidental hypot retrospective study. Eur J Cardiothorac Surg 2001; 20: 58-64 defibrillation attempts or additional boluses of medication 4. Schneider SM. Hypothermia: from recognition to rewarming Emerg Me until the core temperature rises above 30C(86F).9 Sinus Rep.1992;13:1-20 bradycardia may be physiologic in severe hypothermia (ie, 5.Gilbert M. Busund R. Skagseth A, Nilsen PA, Solbe JP. Resuscitate from accidental hypothermia of 137C with circulatory arrest. Lancet. appropriate to maintain sufficient oxygen delivery when hypothermia is present), and cardiac pacing is usually not 6. Larach MG. Accidental hypothermia. Lancet. 1995: 345: 493-498 indicated 7. Komberger E. Schwarz B, Lindner KH, Mair P. Forced air surfac In-hospital treatment of severely hypothermic (core tem- rewarming in patients with severe accidental hypothermia. Resuscitation 1999:4l:105-l11 erature <30C [86FD victims in cardiac arrest should be 8. Roggla M. Frossard M, Wagner A. Holzer M, Bur A. Rogela G. Seve directed at rapid core rewarming. Techniques for in-hospit accidental hypothermia with or without her nic instability: controlled rewarming include administration of warmed, rewarming without the use of extracorporeal circulation. Wien Wochenschr.2002;114:315-320. humidified oxygen(42 C to 46C[108 Fto 115FD, warmed 9. Reuler JB. Hypothermia: pathophysiology, clinical settings, and man- IV fluids(normal saline)at 43.C(109F), peritoneal lavage agement. Ann Intern Med. 1978: 89: 519-527of defibrillation attempts that should be made have not been established. But if ventricular tachycardia (VT) or VF is present, defibrillation should be attempted. Automated exter￾nal defibrillators (AEDs) may be used for these patients. If VF is detected, it should be treated with 1 shock then immediately followed by resumption of CPR, as outlined elsewhere in these guidelines for VF/VT (see Part 5: “Elec￾trical Therapies: Automated External Defibrillators, Defibril￾lation, Cardioversion, and Pacing”). If the patient does not respond to 1 shock, further defibrillation attempts should be deferred, and the rescuer should focus on continuing CPR and rewarming the patient to a range of 30°C to 32°C (86°F to 89.6°F) before repeating the defibrillation attempt. If core temperature is
30°C (86°F), successful conversion to nor￾mal sinus rhythm may not be possible until rewarming is accomplished.11 To prevent further core heat loss, remove wet garments and protect the victim from further environmental exposure. Insofar as possible this should be done while providing initial BLS therapies. Beyond these critical initial steps, the treat￾ment of severe hypothermia (temperature
30°C [86°F]) in the field remains controversial. Many providers do not have the time or equipment to assess core body temperature or to institute aggressive rewarming techniques, although these methods should be initiated when available.4,9,12,13 Modifications to ACLS for Hypothermia For unresponsive patients or those in arrest, endotracheal intubation is appropriate. Intubation serves 2 purposes in the management of hypothermia: it enables provision of effective ventilation with warm, humidified oxygen, and it can isolate the airway to reduce the likelihood of aspiration. ACLS management of cardiac arrest due to hypothermia focuses on more aggressive active core rewarming techniques as the primary therapeutic modality. The hypothermic heart may be unresponsive to cardiovascular drugs, pacemaker stimulation, and defibrillation.9 In addition, drug metabolism is reduced. There is concern that in the severely hypothermic victim, cardioactive medications can accumulate to toxic levels in the peripheral circulation if given repeatedly. For these reasons IV drugs are often withheld if the victim’s core body temperature is
30°C (86°F). If the core body temper￾ature is 30°C, IV medications may be administered but with increased intervals between doses. As noted previously, a defibrillation attempt is appropriate if VF/VT is present. If the patient fails to respond to the initial defibrillation attempt or initial drug therapy, defer subsequent defibrillation attempts or additional boluses of medication until the core temperature rises above 30°C (86°F).9 Sinus bradycardia may be physiologic in severe hypothermia (ie, appropriate to maintain sufficient oxygen delivery when hypothermia is present), and cardiac pacing is usually not indicated. In-hospital treatment of severely hypothermic (core tem￾perature
30°C [86°F]) victims in cardiac arrest should be directed at rapid core rewarming. Techniques for in-hospital controlled rewarming include administration of warmed, humidified oxygen (42°C to 46°C [108°F to 115°F]), warmed IV fluids (normal saline) at 43°C (109°F), peritoneal lavage with warmed fluids, pleural lavage with warm saline through chest tubes, extracorporeal blood warming with partial by￾pass,4,9,12,14,15 and cardiopulmonary bypass.16 During rewarming, patients who have been hypothermic for 45 to 60 minutes are likely to require volume adminis￾tration because the vascular space expands with vasodilation. Routine administration of steroids, barbiturates, and antibiot￾ics has not been documented to increase survival rates or decrease postresuscitation damage.17,18 If drowning preceded hypothermia, successful resuscita￾tion is unlikely. Because severe hypothermia is frequently preceded by other disorders (eg, drug overdose, alcohol use, or trauma), the clinician must look for and treat these underlying conditions while simultaneously treating the hypothermia. Withholding and Cessation of Resuscitative Efforts In the field resuscitation may be withheld if the victim has obvious lethal injuries or if the body is frozen so that nose and mouth are blocked by ice and chest compression is impossible.19 Some clinicians believe that patients who appear dead after prolonged exposure to cold temperatures should not be considered dead until they are warmed to near normal core temperature.10,11 Hypothermia may exert a protective effect on the brain and organs if the hypothermia develops rapidly in victims of cardiac arrest. When a victim of hypothermia is discovered, however, it may be impossible to distinguish primary from secondary hypothermia. When it is clinically impossible to know whether the arrest or the hypothermia occurred first, rescuers should try to stabilize the patient with CPR. Basic maneuvers to limit heat loss and begin rewarming should be started. Once the patient is in the hospital, physi￾cians should use their clinical judgment to decide when resuscitative efforts should cease in a victim of hypothermic arrest. References 1. Holzer M, Behringer W, Schorkhuber W, Zeiner A, Sterz F, Laggner AN, Frass M, Siostrozonek P, Ratheiser K, Kaff A. Mild hypothermia and outcome after CPR. Hypothermia for Cardiac Arrest (HACA) Study Group. Acta Anaesthesiol Scand Suppl. 1997;111:55–58. 2. Sterz F, Safar P, Tisherman S, Radovsky A, Kuboyama K, Oku K. Mild hypothermic cardiopulmonary resuscitation improves outcome after pro￾longed cardiac arrest in dogs. Crit Care Med. 1991;19:379 –389. 3. Farstad M, Andersen KS, Koller ME, Grong K, Segadal L, Husby P. Rewarming from accidental hypothermia by extracorporeal circulation: a retrospective study. Eur J Cardiothorac Surg. 2001;20:58 – 64. 4. Schneider SM. Hypothermia: from recognition to rewarming. Emerg Med Rep. 1992;13:1–20. 5. Gilbert M, Busund R, Skagseth A, Nilsen PÅ, Solbø JP. Resuscitation from accidental hypothermia of 13.7°C with circulatory arrest. Lancet. 2000;355:375–376. 6. Larach MG. Accidental hypothermia. Lancet. 1995;345:493– 498. 7. Kornberger E, Schwarz B, Lindner KH, Mair P. Forced air surface rewarming in patients with severe accidental hypothermia. Resuscitation. 1999;41:105–111. 8. Roggla M, Frossard M, Wagner A, Holzer M, Bur A, Roggla G. Severe accidental hypothermia with or without hemodynamic instability: rewarming without the use of extracorporeal circulation. Wien Klin Wochenschr. 2002;114:315–320. 9. Reuler JB. Hypothermia: pathophysiology, clinical settings, and man￾agement. Ann Intern Med. 1978;89:519 –527. Part 10.4: Hypothermia IV-137