The Cryonics Institute’s 101st Patient
The 101st patient of the Cryonics Institute (CI) is an 18-year-old boy who committed suicide by hydrogen sulfide poisoning. He was reportedly "super bright", but suffered from depression. His parents were aware of the problem and as far as they were aware, anti-depressants and a new school program had elevated their son's spirits. So they were taken by surprise by the suicide. There was evidence that their son had taken the advice of a website that encourages teenagers to commit suicide.
Attempts to revive the boy failed, despite prolonged efforts. The boy's parents were able to prevent an autopsy. They both wanted their son to be cryopreserved.
This case was a post-mortem sign-up. In accordance with CI policies, a post-mortem sign-up patient must be held in dry ice for at least two weeks before CI can accept shipment. The patient's mother was most actively involved in trying to make the best of the situation. She asked for perfusion and she asked CI to shorten the two-week waiting period, but we held to our policies.
After the storage agreement and authorizations had been notarized — and the money wired to CI's bank account — the focus of attention shifted to patient shipping. The family's funeral director was very diligent in maintaining the patient on dry ice and in attempting to ensure that there would be no problems with shipping. The family's funeral director called Delta Airlines and was given misinformation about a 5.5 pound limit to dry ice (the passenger limit, not the cargo limit). "Delta Cares", the department that deals with air transport of human remains was also misinformed. The patient's mother got involved in phoning the airline, also discovering the variety of answers that are given depending upon which person you are talking to.
I called Delta Cargo, who consulted their hazardous materials expert to get the right information — discovering that the information I had received from Delta Cargo in a previous CI case had not been detailed enough. Previously I had been informed that narrow-bodied aircraft had a 100 kilogram limit for dry ice, but this time I was also told that there is a container-limit of 50 kilograms for a large DC 9 and a 40 kilogram limit for a small DC 9. Delta reserves the right to switch aircraft at the last minute, so a 40 kilogram limit should be assumed.
Delta required a Shipper's Declaration for Dangerous Goods. This had not been required for previous CI patient's shipped in dry ice, although I don't know why not because dry ice is certainly classified as a dangerous good. By one account, however, dry ice is only considered a dangerous good when it accompanies another dangerous good. The family's funeral director submitted the form to Delta, but the form was rejected. A checklist of deficiencies accompanied the rejection, but Delta representatives were not too helpful in answering questions about the matter. Both the patient's mother and I attempted to help by doing on-line research. Among other on-line sources, I found the FedEx Dangerous Goods Non-Radioactive Acceptance Checklist to be helpful. I completed a Shipper's Declaration for Dangerous Goods form as I thought it should be completed, scanned it, and e-mailed the scan to the family's funeral director and the patient's mother.
The patient's mother was very worried that 40 kilograms of dry ice would not be adequate. She wanted CI's funeral director to add dry ice to the shipping container immediately after receiving it at the Detroit airport, before driving to CI. I tried to assure her that as long as there was good insulation, 40 kilograms should be adequate. I suggested that the 40 kilograms of dry ice could be supplemented with bags of water-ice that had been pre-cooled in dry ice to provide additional "thermal ballast". I emphasized that dry ice should especially be packed around the head.
At dry ice sublimation temperature (about −80ºC or 193 K) the specific heat capacity of water-ice is about twice that of dry ice. Dry ice is about 1.5 times more dense than water ice at dry ice sublimation temperature, which works in the opposite direction, but that does not mean that water ice could replace dry ice as a better coolant. The major cooling effect is due to the sublimation of the dry ice. As CI Director (and retired Civil Engineer) Alan Mole has pointed out, the heat of sublimation of dry ice is 246 BTU per pound, equivalent to raising the temperature of 750 pounds of water-ice one ºF.
The patient's parents drove to the airport to ensure that their son was loaded onto the airplane without any problems. They were prepared to drive their son to Detroit if necessary. Fortunately, the Shipper's Declaration for Dangerous Goods was accepted and the patient was flown to Detroit without further complications.
|Plenty of dry ice||Andy prepares patient|
The patient was picked-up at the Detroit airport by CI's funeral director Jim Walsh. At the CI facility we saw that the dry-ice had been amazingly well-preserved, thanks to the diligence of the family's funeral director (for whom Mr. Walsh had words of praise). Styrofoam (rather than foamboard insulation) was between the air tray and the shipping box, but there was no styrofoam or foam board in the shipping box itself. Instead, the box was totally filled with the patient, dry ice, and bags of water ice (which had presumably been cooled to dry ice temperature). All of the dry-ice bags were packed at the patient's head and upper body, and all of the water-ice bags covered the lower part of the patient's body. What was so amazing was that there was barely any evidence of any dry ice sublimation (evaporation).
With the help of Mr. Walsh, Andy Zawacki removed the patient, placed him in a sleeping bag on a board, and moved him to the cooling box. The cooling box was pre-cooled to dry ice temperature, and then the patient was placed in CI's computer-controlled cooling box with the new Omega controller at about 11 P.M. Monday evening. The temperature in the cooling box understandably spiked somewhat as the box was opened for insertion of the patient. The patient was cooled from dry ice temperature (about −80ºC) to liquid nitrogen temperature (about −196ºC) in a 22-hour linear ramp cooling. Cracking (a form of stress relief) is not an issue for a straight frozen patient that is cooled at such a rate because the frozen tissue already has micro-fissures.
|Full Cooling curve for the CI's 101st patient (minutes)|
Prior to pre-cooling the cooling box, and before the patient had arrived, I carefully calibrated the Omega controller with ice water at 0ºC and liquid nitrogen at −195.8ºC (which was as close as I could get to −196.0ºC).
|First two hours of cooling||Last 140 minutes of cooling|
I was expecting the cooling to finish at −196ºC by around 10 P.M. Monday evening, but the temperature flattened out at about −194.2ºC and would not go any lower. The controller kept the valve open, pouring liquid nitrogen into the box continuously for twenty to thirty minutes, before we finally accepted that the patient was a cold as he was going to get, and we removed him. To check that my calibration had not been thrown-off, after the patient was removed from the cooling box, I placed the thermocouple back into liquid nitrogen. The temperature dropped to −195.8ºC. The temperature measured by the thermocouple during cooling is ambient temperature inside a cardboard box that is kept in the cooling box with the patient. Before getting the Omega controller, the controlling thermocouple had been in the patient. The most reasonable conclusion is that ambient temperature in the box as measured by the thermocouple in the cardboard box is not as low as the temperature of the patient — and probably cannot drop below −194.4ºC at the lowest, even when the cooling box is being flooded with liquid nitrogen.
In retrospect, all of this should probably have been obvious, but with the previous controller there had been repeated calibration problems, which led me to suspect that the same problem might have been recurring with the new controllers. As a practical consequence, we have adopted the practice of waiting until the curve flattens with the new controller before removing pets or patients, so target temperature was being reached. Now that I have done calibration both before and after cooling, however, I am more confident that the calibration of the new controller is stable, and now have a better idea of what final ambient temperature to expect.
|Patient lifted from cooling box||Patient lowered into cryostat|
Andy and his brother-in-law, David Fulcher, removed the patient from the cooling box, wheeled him to the front on a cart, raised him up to the top of the cryostats in a forklift, and finally lowered him into a cryostat. The 101st CI patient become the fourth patient to occupy cryostat HSSV−6−11.