REVIEW AND APPRAISAL OF PART IV 



R. D. DRIPPS 



Induced hypothermia has heen apphed in the following fields : 



Protection against ischemia. Reduction of hody tcmperatinx- can protect 

 against diminished or ahsent hlood flow. For this reason hypothermia has heen used 

 during interruption of the hlood supply to the whole hody (e.g., during open-heart 

 operations), or to parts of the body (e.g., l)rain, liver, kidney, and gastro-intestinal 

 tract). The degree of protection has not been defined for various temperatures nor 

 for all tissues. These parameters must he outlined. 



Whether low-flow or high-flow pump-oxygenators will replace hypothermia as 

 the method of choice for cardiotomy remains to be seen. The tendency in certain 

 clinics is in this direction. Interestingly enough, hypothermia is not recommended as 

 an adjunct to pump-oxygenators by most workers. 



Specific use in neurosurgery. The reduction in brain size during hypothermia 

 should have a great appeal to neurosurgeons. If the method can be made safer it 

 may have widespread applicability for craniotomy for this reason alone. 



Use in "shock." As expected, a certain degree of protection against hemorrhagic 

 shock has been demonstrated in animals when hypothermia has been used prior to 

 bleeding. In operations known in advance to be associated with a large blood loss 

 and a high incidence of shock this observation may find application. The value of 

 hypothermia in man once shock has become established has not been documented. 

 If shivering could be prevented there would appear to be theoretical grounds for 

 permitting the body temperature of the shocked individual to fall, but studies on 

 this have not been reported. 



Effect on the course of infection. The few data which are available suggest 

 little significant alteration of the course of infection. The influence of hypothermia 

 on the formation of antibodies and other respo'nses to infection deserves inquiry. 

 The value of reducing the body temperature of markedly febrile patients has been 

 recognized for centuries. Therapeutic application of this should be more wide- 

 spread in clinical practice. The use of cooling for three to 10 days has been ex- 

 plored by some European workers in man and by a few investigators in this 

 country in animals. 



A number of clinical problems remain unanswered. Can the clinical impres- 

 sion that a surgical patient after hypothermia has a smoother postoperative course 

 and appears less stressed than one operated upon at normal body temperature be 

 verified by objective means? Observations of this sort tempt one to explore induced 

 hypothermia rather than conventional methods of anesthesia for operations on 

 desperately ill patients, regardless of the procedure contemplated. 



What is the incidence of bleeding during and immediately after hypothermia? Is 

 the reduction of platelets described in this symposium responsible for this, or are 

 other abnormalities of the coagulation process present? Is there a greater tendency 

 towards fibrinolysis? 



The effects of changes in blood viscosity have received little attention. 



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