University Hospital of North Norway:
- located at 69 degrees North latitude – likely the northernmost ECMO center in the world.
- The warmest month is July with a mean air temperature of 11.8C and mean sea temperature of 10.8 C.
- The coldest month is January with a mean air temperature of -4.4 C and mean sea temperature of 5.1 C.
- ECMO program since 1988
- Yearly ECMO volume is approx 20 per year – including postcardiotomy support, ECPR, cardiogenic shock and respiratory failure
- ECMO Retrieval Ambulance service: Since 12/2015: 5 ECMO transports
- Cases are reported through the ELSO registry
Accidental Hypothermia – some definitions:
mild : 32-35 C – preserved capability to maintain core temperature through compensating thermoregulatory mechanisms
Moderate: 28-32 – loss of ability to sustain temperature via either voluntary or autonomic means
Severe: 20-28 – high risk of malignant arrhythmias
Profound: <20 Asystole
The Paper: Hilmo, J et al. Prolonged resuscitation is warranted in arrested hypothermic victims also in remote areas – A retrospective study from northern Norway. Resuscitation , Volume 85 , Issue 9 , 1204 – 1211
- “Nobody is dead until warm and dead”
- retrospective study looking at accidental hypothermia victims with cardiac arrest admitted to UNN between 1985-2013
- no survivors prior to 1999
- 1999-2013: 9/24 (37.5%) survival, defined as alive at 1 year – most with a ‘favorable’ neurologic outcome
- PRIOR studies suggested that asphyxiation, either via snow burial (avalance) or water submersion had a lower chance of survival, but this study suggests that hypothermic arrest during submersion injury may be very different. It is hypothesized that very cold temps create faster cooling rates and aspiration of cold water may induce rapid protective cerebral hypothermia. So drowning victims (asphyxia by submersion in cold water may have a higher survival)
- Hyperkalemia is bad (>8 is bad; >12 is dead)
- Bottom Line: “No patient is dead until they are warm and dead” – current neuroprognostication can’t identify OHCA patients who may be salvageable. So assume they are!
Key ECMO Points:
- Profoundly hypothermic patients cannot generate high flow rates – possibly due to increase blood viscosity. Consider larger cannulae. Torvinde uses 29F venous and 21F arterial as a starting point.
- Rewarm with a veno-arterial temperature gradient of no more than 10 degrees C. Faster rewarming may result in bubble formation. Torvinde does this via the water bath heater/cooler.
- Therapeutic hypothermia is still in play. Torvinde holds the core temp at 36 for 24-28 hours.
- “You’re not dead unless you’re warm and dead” – consider transporting potentially salvageable patients with a reliable history.