JAMES A. MILLER, JR. 239 



nation with sedation, carried his patients down to a minimum of 23.9°C; 

 and Talbott (178) to 23.3°C. Although the subjects in the Dachau experi- 

 ments were at least partially starved, they certainly were in as good 

 condition as Fay's and Talbott's patients, who were in the terminal stages 

 of cancer. Likewise, the thoracic surgeons using hypothermia for cardiac 

 operations employ temperatures in the neighborhood of 26°C (104, 58, 

 177). In their operations, temperatures as low as 22°C have been followed 

 by complete recovery (175, 27). The lowest temperature from which 

 recovery has been reported (16°C) was that of a woman who, previous 

 to exposure to low temperature, had been at least partially narcotized 

 by alcohol (103). 



Artificial Respiration. Since the commonly employed range for hypo- 

 thermia is below that at which respirations cease, artificial respiration 

 is necesary and is routinely employed. Both Bigelow and Swan emphasize 

 the importance of hyperventilation as a means of preventing the accumu- 

 lation of COo in the blood. 



Fluid. Hypothermia causes hemoconcentration. As temperatures below 

 20°C are reached, blood viscosity increases greatly. In Laufman's patient 

 ( 103) he noted that blood in the patient's femoral vein was completely 

 congealed at the time of admission to the hospital. To avoid both the 

 hemoconcentration and the excessively high viscosity of cold blood, Gollan 

 dilutes it with Ringer's solution until a hematocrit of about 25% is 

 reached. Part of his success in carrying dogs to 0°C with recovery may 

 be attributed to his liberal use of blood diluents. 



Ventricular Fibrillation. Many approaches to this problem have been 

 used and with varying degrees of success. Electric defibrillation is by no 

 means infallible. Epinephrine given to stimulate failing hearts was found 

 to increase fibrillation (45, 46). The group at Denver (175, 176) at first 

 used hyperventilation combined with potassium chloride injections to 

 stop fibrillation and calcium to aid in starting the heart again. Later, 

 they found that prostigmine was efTective in preventing ventricular fibril- 

 lation in dogs and have been using it routinely as a prophylaxis (153). 

 They have performed a large number of operations with a very low 

 incidence of death from fibrillation (177). 



People working with pump oxygenators and extracorporeal cooling 

 report very little difficulty with ventricular fibrillation. Juvenelle has 

 permitted fibrillation to continue five hours in a dog and upon rewarming 

 regular effective beats recommenced. Gollan uses premedication with quini- 

 dine sulphate (113, 56) to prevent fibrillation during the rewarming proc- 

 ess. He emphasizes also the importance of reducing coronary flow to pre- 

 vent cardiac dilatation and pressure ischemia of the myocardium which he 

 believes contributes to tlie tendency of the cold heart to fibrillate (78). 



