X-Message-Number: 2483 Date: Wed, 8 Dec 93 22:56:24 CST From: Subject: CRYONICS Brain injury Brook H. Norton: > Is is simply the case that when resuscitation starts within 5 min of > clinical death, that the cryoprotectant reaches the entire brain, > but when resuscitation starts later, cryoprotectant does not reach > some areas of the brain, areas which then undergo a local straight > freeze? Things aren't really that bad. Most of the swelling responsible for the "no re-flow" phenomenon occurs *after* blood flow is restarted with the brain in a metabolically unbalanced condition. In fact, swelling of ischemically-shocked brains doesn't max out until after several hours of respirator support. Cryonics patients are administered drugs to minimize brain swelling right from the start of cardiopulmonary support. Hypothermia is also induced as quickly as possible. These measures help to maintain patency of the cerebral vasculature beyond what would ordinary be expected in clinical medicine. At the Institute for Biodiagnostics here in Winnipeg, Canada there is in fact a research group that specializes in the physiology of slowed metabolism. Their research includes cardioplegia (stopping of the heart for open-heart surgery), hypothermic organ preservation, and *the beneficial effects of hypothermia on ischemically-shocked brains*. In fact, earlier this year I sat through an entire seminar extolling the virtues and therapeutic effects of hypothermia administered *after* an ischemic insult to the brain. It's this kind of research that gives me great confidence that cryonics patients experiencing 5-30 minutes of ischemia are in better shape than ordinary medicine would lead one to expect. My own Mother experienced 9 minutes of warm cardiac arrest followed by 3 hours of inefficient low-impulse CPR during slow external cooling in her cryonic suspension. 24 hours later, and 2000 miles away (at Alcor) her brain perfused with glycerol excellently. This is not to say that time isn't important. If CPR and drug administration is delayed beyond 30 minutes, blood clotting will become a problem. As Thomas Donaldson points out, there are indeed many cryonics patients who suffered protracted cardiac arrest and who did not purfuse well (or at all) as a result. --- Brian Wowk Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2483