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Three Part Question

In [accidental severe hypothermia (less than or equal to 30 degrees celcius) induced ventricular fibrillation in adults] is [defibrillation] [effective at restoring a sinus rhythm]?

Clinical Scenario

A 50 year old man is found collapsed in the snow on a very cold winter's night. He is admitted to hospital unconscious with adjuvant cardiopulmonary resuscitation and a low reading rectal thermometer measures his core temperature to be 26 oC. He is in ventricular fibrillation. Should an attempt at defibrillation be made at this temperature or should he be re-warmed first and then defibrillated?

Search Strategy

Medline 1966 – 06 using Ovid interface.
[AED$ or automated external defibrillat$ or defibrillat$ or VF or ventricular fibrillati$ or CPR or cardiopulmonary resus$ or ALS or advanced life support] and [severe hypothermia or hypothermi$]mp. [mp=title, original title, abstract, name of substance word, subject heading word].
Limited to humans and English language
Cochrane Library Issue 3 2006:
hypothermia [title, abstract or keywords] and defibrillation [title, abstract or Keywords] or ventricular fibrillation [title, abstract or keywords].

Search Outcome

Total of 385 papers initially found.
Minimal data set criteria were:
-Accidental induction of hypothermia
-Patient in Ventricular fibrillation
-Core temperature recorded as <30oC
-Adults (> 18 years old)
-Adjuvant cardiopulmonary resuscitation
-Core temperature of defibrillations stated.
This left 17 papers that were relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Towne WD et al. 1972. USA.	58 yr old	Case Report	Successful defibrillation at 34.4 oC.	Repeated attempts at external defibrillation unsuccessful.
Schissler P et al. 1981. USA.	67 yr old	Case Report	Successful defibrillation at 30.0 oC.	Previous shock at 22.2 oC unsuccessful.
Nordrehaug JE. 1982. Norway.	33 yr old	Case Report	Successful defibrillation at 28 oC.	Defibrillation attempts at 24, 26 and 27 oC unsuccessful.
Althaus U et al. 1982. Switzerland.	40, 42 and 24 yr olds	Case Series	Successful defibrillation at 26, 36 and 29 oC respectively.	Two cases were of successful defibrillation at < 30 oC.
Splittgerber FD et al. 1986. USA.	Adults less than or equal to 18 yrs. 6 cases	Case Series,11 cases ineligible	All patients that lived defibrillated at >34 oC.	Unsuccessful defibrillations attempted at temperatures lower than 30 oC. Two of the cases died.	Further 11 cases analysed from literature, not analysed here as risk of duplication.
Cohen DJ et al. 1988. USA.	32 yr old.	Case Report	Successful defibrillation at 30 oC.	Earlier attempts at defibrillation failed.
Walpoth BH et al. 1990. Switzerland.	4 adults	Case Series, 12 cases ineligible	Mean temperature of successful defibrillation at 25.6 oC.		No exact patient details given
Wisborg T. et al. 1991. Norway.	33 yr old	Case Report	Successful defibrillation at 31 oC.	Rewarmed prior to first shock.
Bolgiano E et al. 1992. USA.	22 yr old.	Case Report	Successful defibrillation at 30 oC.	Initial defibrillation at 24 oC unsuccessful.	Data on other cases did not meet minimal data set criteria
Wolfe CS. 1993. USA.	38 yr old	Case Report	Successful defibrillation at 24 oC.	Initial defibrillation at 23 oC unsuccessful.
Schwartz AJ et al. 1997. Austria.	54 yr old	Case conference Case Report	Successful defibrillation at 31 oC.	Earlier attempts at defibrillation failed.
Ireland AJ et al. 1997. UK.	48 yr old	Case Report	Successful defibrillation at 24.3 oC.	First shock was sufficient.
Steedman DJ et al. 1997. UK.	29 yr old	Case Report	Successful defibrillation at 37 oC.	Initial defibrillations unsuccessful at 28.3, 29.0 and 31 oC.
Thomas R et al. 2000. UK.	82 yr old	Case Report	Successful defibrillation at 25.6 oC.	Patient eventually died.
Ko CS et al. 2002. UK.	37 yr old	Case Report	Successful defibrillation at 37 oC.	Previous defibrillation at 30 oC unsuccessful.	Core temperature recorded (17 oC) tympanic, therefore accuracy unclear.
Mulpar AK et al, 2004, UK	20 yr old	Case Report	Successful defibrillation at 28 oC	Previous defibrillation at 25 oC unsuccessful.
Moser B et al, 2005, Austria	62 year old	Case Report	Successful defibrillation at 29oC	No previous defibrillation attempts.

Comment(s)

The only published data on this subject is in the form of case reports and a few case series. No higher-level evidence is available. From these there is insufficient data to definitively say whether or not defibrillation is effective in severe hypothermia. 55.6% of cases do however report successful defibrillation at temperatures at or below 30 degrees celcius (15 of 27 cases). This may be due to publication bias and further work would be necessary to be sure.

Clinical Bottom Line

It is reasonable to attempt defibrillation at temperatures below 30 degrees celcius in accidental severe hypothermia. This theraputic strategy is supported by the current European Resuscitation Council guidelines (18).

References

1. Towne WD, Geiss WP, Yanes HO et al. Intractable ventricular fibrillation associated with profound accidental hypothermia- Successful treatment with partial cardiopulmonary bypass. The New England Journal of Medicine. 1972; 287 (22): 1135-6.
2. Schissler P, Parker MA and Scott SJ. Profound hypothermia: Value of prolonged cardiopulmonary resuscitation. Southern Medical Journal. 1981; 74 (4): 474-7.
3. Nordrehaug JE. Sustained ventricular fibrillation in deep accidental hypothermia. British Medical Journal 1982; 284: 867-8.
4. Althaus U, Aeberhard P, Schupbach P et al. Management of profound accidental hypothermia with cardiorespiratory arrest. Annals of Surgery. 1982; 195 (2): 492-5.
5. Splittgerber FH, Talbert JG, Sweezer WP et al. Partial cardiopulmonary bypass for core rewarming in profound accidental hypothermia. American Surgeon. 1986; 52 no.8: 407-12.
6. Cohen DJ, Cline JR, Lepinski SM et al. Resuscitation of the hypothermic patient. American Journal of Emergency Medicine. 1988; 6 (5):475-8.
7. Walpoth BH, Locher T, Leupi P et al. Accidental deep hypothermia with cardiopulmonary arrest: extracorporeal blood rewarming in 11 patients. European Journal of Cardio-thoracic surgery. 1990; 4: 390-3.
8. Wisborg T, Husby P, Engedal H, et al. Anesthesiologist-manned helicopters and regional extracorporeal circulation facilities: a unique chance in deep hypothermia. Artic Medical research. 1991; 50 (Supplement 6): 108-11.
9. Bolgiano E, Sykes L, Barish RA et al. Accidental hypothermia with cardiac arrest: recovery following rewarming by cardiopulmonary bypass. Journal of Emergency Medicine. 1992; 10: 427-33.
10. Wolfe CS. Severe hypothermia associated with prolonged cardiorespiratory arrest and full recovery. Journal of the American Board of Family Practice. 1993; 6 (6): 594-6.
11. Schwartz AJ and Hensley FA. Successful resuscitation of a patient with severe accidental hypothermia and prolonged cardiocirculatory arrest using cardiopulmonary bypass. Journal of Cardiothoracic and vascular Anesthesia. 1997; 11 (7): 901-4.
12. Ireland AJ, Pathi VL Crawford R et al. Back from the dead: extracorporeal rewarming of severe accidental hypothermia in accident and emergency. Journal of Accident and Emergency Medicine. 1997. 14 (4): 255-7.
13. Steedman DJ, Rainer T and Campanella C. Cardiopulmonary resuscitation following profound immersion hypothermia. Journal of Accident and Emergency Medicine. 1997; 14: 170-2.
14. Thomas R and Cahill CJ. Successful defibrillation in profound hypothermia (core body temperature 25.6 oC). Resuscitation. 2000; 47:317-20.
15. Ko CS, Alex J, Jefferies S et al. Dead? Or just cold: profound hypothermic patients with no signs of life. Emergency Medical Journal. 2002; 19 (5): 478-9.
16. Soar J, Deakin CD, Nolan JP et al. European Resuscitation Council Guidelines for Resuscitation 2005. Section 7. Cardiac arrest in special circumstances. Resuscitation. 2005; 67S1: S135-70.
17. Mulpur AK, Mirsadraee S, Hassan TB et al. Refractory ventricular fibrillation in accidential hypothermia: salvage with cardiopulmonary bypass. Perfusion. 2004; 19: 311-4.
18. Moser B, Voelckel W, Gardetto A et al. One night in a snowbank: a case report of severe hypothermia and cardiac arrest. Resuscitation. 2005. 65: 365-8.