Bypass is better than external rewarming after hypothermic cardiac arrest
Date First Published:
March 1, 2000
Last Updated:
April 11, 2001
Report by:
Claudia Webster-Smith, Medical Student (Manchester Royal Infirmary)
Search checked by:
Angaj Ghosh, Manchester Royal Infirmary
Three-Part Question:
In [severely hypothermic patients who have suffered cardiac arrest] is [core rewarming by cardiopulmonary bypass better than external rewarming] at [re-establishing spontaneous circulation and leading to eventual discharge]?
Clinical Scenario:
A 24 year-old woman is brought into the Emergency Department having fallen into a frozen lake. Passers-by heard her cries for help and alerted the Emergency Services who rescued her 15 minutes later. On the way to hospital she suffered a cardiac arrest. Her core temperature on arrival is 25 degrees centigrade. You know that she needs rewarming but wonder whether her eventual outcome will be improved by cardiopulmonary bypass rather than external rewarming.
Search Strategy:
Medline 1966-09/00 using the OVID interface.
Search Details:
([exp heart arrest OR cardiac arrest.mp] AND [exp hypothermia OR hypothermia.mp OR hypothermic.mp OR exp body temperature] AND [exp heat OR exp heating OR exp rewarming OR warming.mp OR rewarming.mp]) LIMIT to human AND english
Outcome:
114 papers found of which 111 were irrelevant or of insufficient quality. The remaining 3 papers are shown in the table.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Cardiopulmonary bypass resuscitation for accidental hypothermia. Vretenar DF. Urschel JD. Parrott JC. Unruh HW. 1994, Canada. | 68 hypothermic patients with a mean core temperature of 21 degrees centigrade of whom 61 were in cardiac arrest. All patients placed on cardiopulmonary bypass |
Review | Overall survival | 60% | Publication bias likely as success more likely to be reported than failure. |
| Survival if core temperature < 15 degrees | 0% | ||||
| Return to previous function | 60% of survivors | ||||
| Deep accidental hypothermia and cardiac arrest - rewarming with forced air. Koller R, Schnider TW, Neidhart P. 1997, Switzerland. | 5 patients with core temperature below 30 degrees centigrade of whom 2 were in cardiac arrest | Cohort | Overall survival | 100% | Small numbers |
| Return to previous function | 100% | ||||
| Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming. Walpoth BH, Walpoth-Alsan BN, Mattle HP et al. 1997 | 32 of 46 patients in cardiac arrest with core temperature below 28 degrees centigrade. All patients placed on cardiopulmonary bypass |
Prospective cohort | Overall survival | 15/32 (45%) | Unclear why patients selected for bypass |
Author Commentary:
None of the studies directly answer the question. It appears that there is a significant functional recovery following severe hypothermic cardiac arrest, and cardiopulmonary bypass seems to be an efficacious treatment. The number of patients treated by external rewarming is very small and more work will be needed before this can be recommended in preference to bypass.
Bottom Line:
In severely hypothermic patients in cardiac arrest cardiopulmonary bypass should be considered.
References:
- Vretenar DF. Urschel JD. Parrott JC. Unruh HW.. Cardiopulmonary bypass resuscitation for accidental hypothermia.
- Koller R, Schnider TW, Neidhart P.. Deep accidental hypothermia and cardiac arrest - rewarming with forced air.
- Walpoth BH, Walpoth-Alsan BN, Mattle HP et al.. Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming.