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Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming
Outcome of Survivors of Accidental Deep Hypothermia bated with Extracorporeal Blood Warming
and Circulatory
Arrest
Walpoth BH, WalDoth-Aslan BN, Mattle HP, Radanov BP, Schroth G, Schaeffler L, et al. N Engl J Med 1997;337:1joo-5. Cardiopulmonary bypass (CPB) has been used to rewarm victims of accidental deep hypothermia. Unlike other rewarming techniques, this procedure restores organ perfusion immediately in patients with inadequate circulation. This study evaluated the long-term outcome of survivors of accidental deep hypothermia with circulatory arrest who had been rewarmed with CPB. Methods. Deep hypothermia (core temperature < 28°C) with circulatory arrest was found in 46 of 234 patients with accidental hypothermia. In 32 of the 46 patients, rewarming with CPB was attempted, resulting in 15 long-term survivors. In most of these patients, deep
hypothermia developed after mountaineering accidents or suicide attempts. After an average (* SD) of 6.7 (* 4.0) years of follow-up, we obtained the patients’ medical histories and performed neurologic and neuropsychologic examinations, neurovascular ultrasound studies, electroencephalography, and magnetic resonance imaging of the brain. Results. The average age of these patients was 25.2 (& 9.9) years; seven were women, and eight were men. The mean interval from discovery of the patient to rewarming with CPB was 141 (* 50) minutes (range, 30 to 240). At follow-up no hypothermia-related sequelae that impaired quality of life were discov-
ered. Neurologic and neuropsychologic deficits observed in the early period after rewarming had fully or almost completely disappeared. One patient had cerebellar atrophy on magnetic resonance imaging with mild clinical signs, a condition that may have been caused by hypothermia. Other clinical abnormalities were either preexisting or a result of injuries not related to hypothermia. Conclusion. This clinical experience demonstrates that young, otherwise healthy people can survive accidental deep hypothermia with no or minimal cerebral impairment, even with prolonged circulatory arrest. CPB appears to be an efficacious rewarming technique.
The authors report impressive results ture of 2O”C, cardiac arrest is tolerated in patients treated with CPB to provide for up to 30 minutes without significant extracorporeal blood warming after acci- neurologic or neuropsychologic deficits. dental deep hypothermia with core tem- The authors further note that none of the perature less than 28°C. Fiieen young patients had asphyxia or hypoxic brain patients without cardiovascular disease damage before hypothermia developed. were reviewed. Incidents producing hy- These problems frequently occur in pothermia included falls while on moun- avalanche or drowning victims. Asphyxia tain excursions, ice water immersion, preceding cooling increases the risk of and exposure after suicide attempts. death. Third, survivors were young and The authors provide a variety of rea- healthy with no underlying cardiovascusons that may account for the good sur- lar risk factors. vival rate and favorable outcome for this The authors also suggest a favorable patient group. First, they note that hy- impact of rescue organizations, particupothermia was deep, increasing the larly the use of helicopter teams in the brain’s tolerance to ischemia. Metabolic initial management of these individuals. processes were slowed, and global oxy- They emphasize that during transportagen consumption reduced. The protec- tion and during initial care at the hospitive effect of moderate hypothermia is tal, hypothermia was maintained and pabeing investigated in the treatment of tients were rewarmed only after CPB was traumatic brain injury. Deep hypotherinitiated. mia routinely is used in a variety of carFinally, the authors suggest study of diovascular procedures when circulatory rewarming using CPB, which has a variarrest is required. With a core tempera- ety of theoretical advantages compared
with other rewarming methods. CPB is a rapid method of rewarming, provides immediate circulatory support, and may im prove tissue perfusion by hemodilution, allowing rapid correction of metabolic and toxic derangements. In addition, the heart is rewarmed before the rest of the body, preventing shock as a result of pe ripheral vasodilatation. These data suggest that CPB is the rewarming method of choice for accidental deep hypothermia in association with circulatory arrest. However, appropriate clinical limits of core temperature justifying attempts of the use of extracorporeal circulation remain undefined. Although the availability of extracorporeal circulation and support teams may be limited to larger medical centers, this report is encouraging because it demonstrates prolonged patient tolerance of hypothermia during appropriate management out of hospital by air medical and other EMS personnel.
Background.
COMMENT
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Air Medical Journal
17:3
July-September
1998
135
and Circulatory
Arrest
Walpoth BH, WalDoth-Aslan BN, Mattle HP, Radanov BP, Schroth G, Schaeffler L, et al. N Engl J Med 1997;337:1joo-5. Cardiopulmonary bypass (CPB) has been used to rewarm victims of accidental deep hypothermia. Unlike other rewarming techniques, this procedure restores organ perfusion immediately in patients with inadequate circulation. This study evaluated the long-term outcome of survivors of accidental deep hypothermia with circulatory arrest who had been rewarmed with CPB. Methods. Deep hypothermia (core temperature < 28°C) with circulatory arrest was found in 46 of 234 patients with accidental hypothermia. In 32 of the 46 patients, rewarming with CPB was attempted, resulting in 15 long-term survivors. In most of these patients, deep
hypothermia developed after mountaineering accidents or suicide attempts. After an average (* SD) of 6.7 (* 4.0) years of follow-up, we obtained the patients’ medical histories and performed neurologic and neuropsychologic examinations, neurovascular ultrasound studies, electroencephalography, and magnetic resonance imaging of the brain. Results. The average age of these patients was 25.2 (& 9.9) years; seven were women, and eight were men. The mean interval from discovery of the patient to rewarming with CPB was 141 (* 50) minutes (range, 30 to 240). At follow-up no hypothermia-related sequelae that impaired quality of life were discov-
ered. Neurologic and neuropsychologic deficits observed in the early period after rewarming had fully or almost completely disappeared. One patient had cerebellar atrophy on magnetic resonance imaging with mild clinical signs, a condition that may have been caused by hypothermia. Other clinical abnormalities were either preexisting or a result of injuries not related to hypothermia. Conclusion. This clinical experience demonstrates that young, otherwise healthy people can survive accidental deep hypothermia with no or minimal cerebral impairment, even with prolonged circulatory arrest. CPB appears to be an efficacious rewarming technique.
The authors report impressive results ture of 2O”C, cardiac arrest is tolerated in patients treated with CPB to provide for up to 30 minutes without significant extracorporeal blood warming after acci- neurologic or neuropsychologic deficits. dental deep hypothermia with core tem- The authors further note that none of the perature less than 28°C. Fiieen young patients had asphyxia or hypoxic brain patients without cardiovascular disease damage before hypothermia developed. were reviewed. Incidents producing hy- These problems frequently occur in pothermia included falls while on moun- avalanche or drowning victims. Asphyxia tain excursions, ice water immersion, preceding cooling increases the risk of and exposure after suicide attempts. death. Third, survivors were young and The authors provide a variety of rea- healthy with no underlying cardiovascusons that may account for the good sur- lar risk factors. vival rate and favorable outcome for this The authors also suggest a favorable patient group. First, they note that hy- impact of rescue organizations, particupothermia was deep, increasing the larly the use of helicopter teams in the brain’s tolerance to ischemia. Metabolic initial management of these individuals. processes were slowed, and global oxy- They emphasize that during transportagen consumption reduced. The protec- tion and during initial care at the hospitive effect of moderate hypothermia is tal, hypothermia was maintained and pabeing investigated in the treatment of tients were rewarmed only after CPB was traumatic brain injury. Deep hypotherinitiated. mia routinely is used in a variety of carFinally, the authors suggest study of diovascular procedures when circulatory rewarming using CPB, which has a variarrest is required. With a core tempera- ety of theoretical advantages compared
with other rewarming methods. CPB is a rapid method of rewarming, provides immediate circulatory support, and may im prove tissue perfusion by hemodilution, allowing rapid correction of metabolic and toxic derangements. In addition, the heart is rewarmed before the rest of the body, preventing shock as a result of pe ripheral vasodilatation. These data suggest that CPB is the rewarming method of choice for accidental deep hypothermia in association with circulatory arrest. However, appropriate clinical limits of core temperature justifying attempts of the use of extracorporeal circulation remain undefined. Although the availability of extracorporeal circulation and support teams may be limited to larger medical centers, this report is encouraging because it demonstrates prolonged patient tolerance of hypothermia during appropriate management out of hospital by air medical and other EMS personnel.
Background.
COMMENT
~-----
Air Medical Journal
17:3
July-September
1998
135