X-Message-Number: 2099 Date: Tue, 13 Apr 93 10:30:30 CDT From: Brian Wowk <> Subject: CRYONICS Cooldown Capsules Alcor cools its patients below freezing by immersing them in a bath of stirred silicone oil to which dry ice is slowly added. This method ensures that the patients' temperature is reduced rapidly and uniformly to -79'C (dry ice temperature). The process is typically complete in 36 hours, and costs (according to Alcor's "Blue Book") about $1000 for whole body patients. Final cooling from -79'C to -196'C is achieved by suspending the patient in a dewar and slowly decreasing the ambient air temperature by adding LN2 under computer control (the computer control recently added by Keith Henson). The air (actually nitrogen vapor) must be vigorously stirred to prevent stratification. This process is complex, labor-intensive, and expensive. It requires about two weeks and costs $7000 for whole body patients (most of the cost being a dewar usage charge). I would like to suggest a way that a -130'C Cold Room can further reduce the cost of doing cryonics. After reaching -79'C, the patient can be removed from the silicone oil and placed in a "cooldown capsule" with about 6" of fiberglass insulation wrapped around them. The capsule is then lowered into the Cold Room where the patient will cool at a rate of about 50 watts, or 1'C per hour. This is the initial cooling rate. Because the rate of cooling is proportional to the temperature difference between the patient and -130'C, the patient temperature will follow a slow exponential approach to -130'C with -128'C reached in about one week. This is nature's own automation; it requires no control system and no supervision. The cost and security advantages are obvious. The patient is stored safely underground in the Cold Room during the cooldown, and expensive dewars are no longer required. The savings will accrue quickly as our caseload increases and we don't have to buy new dewars to cool multiple patients simultaneously. If the Blue Book accounting is correct, using the Cold Room instead of a dewar for cooldowns will knock at least $4000 off the front-end costs of suspension. This is significant because front-end savings compound over time. For example, the nominal interest on $4000 can reduce storage costs by $150 a year (about *half* the total storage cost in a Cold Room). This is just one more reason to build a Cold Room. --- Brian Wowk Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2099