We have continued to research past medical case studies on therapeutic hypothermia, particularly looking for longer-duration treatment periods on people. To date, 7-days was the longest inducement period for a patient we had found. That is until now... We have found a Chinese research study published in 2000 in the Journal of Neurosurgery that included treatment periods of up to 14-days! Patients being maintained in a sub-cooled (33-35 deg-C), inactive state for two weeks.
This is cool news! In addition to nearly doubling the past record we had identified, the medical outcomes for these cases remained very positive.
Here are some stats from the report:
- Study monitored outcome of 87 patients with sever traumatic brain injury, with 43 receiving TH treatment for 3 to 14 days, and 44 assigned to "normo-thermia"
- After 1-year, the mortality rate was 45% for non-TH group and only 25% for TH recipients
- Rate of favorable outcome was only 27% for non-TH but over 46% for TH recipients.
- No neurological deficits or metabolic disorders encountered
Why is this important? Besides providing further evidence that we can sustain torpor in humans for lengthy time periods, we could still send the crew to Mars within this 14-day limit if we can not get the inducement period extended to the order of months. Our "sentinel protocol" would have each crew member on a 12-day torpor + 2-day wake cycle in route to Mars. For added safety and mission monitoring, we would rotate through the crew members such that only one was awake at a time. Their activity levels would still be generally low and our current DRA 5 habitat design could easily support a conscious crew member with the current volume and consumables margins. Our preference is still for the full-duration mission torpor, but this is potentially a very viable alternative!