COOLING PATIENTS— LEWIS. RING and ALDEN 395 



Our use of surface cooliiii;- for fehrile palients arose directlv out of our interest in 

 livpothernn'a for inlracardiac surgery. ■'■• ' I'hv tir>t ])atient we treated was a 2<->-vear- 

 old woman ( IMI. No. 846504 j who had just undergone an operation for an atrial 

 septal defect complicated hy mitral stenosis. She was considered to he a poor 

 operative risk hecause of this additional lesion and also hecause she had mild con- 

 gestive heart failure, hut despite these complications she withstood the operation 

 well. Her temperature rose to 104.2° F. a few hours after surgery, however, and 

 with this her heart rate climhed to 140, her systolic hlf)od pressure fell helow SO. and 

 she developed pulmonary edema. It was necessary to assist her l)reathing, with an 

 anesthesia machine working through a tracheotomy tube, in order to avoid cyanosis. 

 These measures did not seem to be enough to save her. We then lowered her body 

 temperature rapidly to 96° F. by wrapping her in the same refrigerating blankets 

 that had cooled her for the heart operation a few hours earlier. The effect was 

 gratifying. Her pulse rate fell and her blood pressure rose slowdy. After a few 

 hours, it was possible to stop assisting her breathing. For several days it was neces- 

 sary to keep her body temperature below normal. If the temperature was allowed to 

 rise above 99° F. she would suffer an immediate and apparently detrimental in- 

 crease in pulse and respiratory rates. After five days, cooling was no longer re- 

 quired and the remainder of her hospital course was untroubled. 



In the one and one-half years since this first patient was successfully treated, we 

 have used surface cooling to treat 24 other gravely ill, hyperthermic patients. 



Method. The two essential features of the technique are surface cooling with a 

 large refrigerating blanket and the administration of enough sedatives to prevent 

 shivering. The patient is placed supine on a bed-sized cooling blanket (figs. 1 and 2) 

 which consists of a long rubber tube sewn between two rubberized sheets. This tube 

 runs back and forth the length of the blanket and a cold anti- freeze solution is 

 pumped through it by a special machine' which can either cool or warm the solu- 

 tion, and consequently the blanket, to any desired temperature. At the start the 

 blanket is cooled to 40-50° F. and occasionally in obese patients ice bags or ice 

 chips are placed over the groins and axillae in addition. This intense surface cooling 

 will cause shivering unless the patient is deeply comatose or properly sedated. 



For sedation we have used chlorpromazine and phenobarl)ital sodium intrave- 

 nously. When shivering first appears, 50 milligrams of chlorpromazine are given 

 and if shivering is still present ten minutes later, 0.13 or 0.20 gram of pheno- 

 barbital sodium are given. In another ten minutes, if shivering still persists, an ad- 

 ditional 50 milligrams of chlorpromazine are administered. This is usually enough, 

 but further 50 milligram doses of chlorpromazine may be necessary if the patient 

 is large or if he has been unusually active just before the cooling was started. In 

 any case, enough is given to suppress all shivering — even the slight tremor that 

 may be detected by palpating the pectoralis major muscles. In an occasional patient 

 as much as 200 milligrams of chlorpromazine has been given during the first two or 

 three hours of cooling. 



After the temperature has started to fall less cooling and less sedation are re- 

 quired. It may be possible to stop administering sedatives altogether wdien the tem- 

 perature has reached normal, but in S(Mne cases an occasional dose of chlorpro- 



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