RENAL FUNCTIONAL RESPONSE TO HYPOTHERMIA AND 

 ISCHEMIA IN MAN AND DOG 



JOHN H. MOVER. GEORGE C. MORRLS and .\[1CHA1-:1. E. I)i- l^.AKEY 



With the use of homograft replacement of the ahdomina] aorta, interruption of 

 the blood supply to the kidney frequently becomes necessary. 1 f the renal ischemia 

 is prolonged, irreversible renal damage may result. Therefore, it Ijeconies necessary 

 to explore methods for either maintaining the blood supply to the kidne_\- or reduc- 

 ing the metabolic processes within the kidneys so that irreversible renal <lamage 

 does not result frt)m the ischemia. One approach wcnild be the use of hypothermia 

 to reduce the metal)olic requirement of these tissues. Investigation of this prob- 

 lem was undertaken in the following study. The observations can be divided into 

 three parts: (I) observations on the effect of hypothermia on the kidney; 

 (II) observations on the effect of ischemia on the kidney and the resultant renal 

 damage produced by this ischemia and; (III) the protective effect of hypothermia 

 against the renal damage produced Ijy ischemia. 



METHODS 



The effect of hypothermia on renal hemodynamics and on water and 

 electrolyte excretion. The effect of hypothermia was studied in 20 dogs. The 

 dogs were anesthetized with pentol)arbital (30 mg/kg). Following ade(|uate con- 

 trol observations, the animals were made hypothermic with a fluid cooled blanket 

 and an electrically controlled temperature regulator ( Therm-( )-I\ite Product). 

 The body temperature was slowly reduced to 80° F. over a one to two hour period, 

 maintained at this level for two hours, and then slowly increased to the control 

 levels. 



Observations were made on glomerular filtration rate and renal plasma flow 

 using creatinine and para-aminohippurate clearances respectively. Sodium and 

 water excretion were determined using the Beckman h'lame I 'hotometric method. 

 After the dogs were anesthetized, three 10-minute control periods were collected. 

 As the temperature was lowered, two 10-minute periods were collected at 2)2° C. 

 (90° F. ) and three periods at 26° C. (80° F. ). After the temperature had been 

 maintained at 25 to 27° C. for two hours, three additional 10-minute periods were 

 collected. Then the temperature was increased to the control levels and observa- 

 tions on renal hemodynamics were again made for three 10-minute periods. These 

 were repeated 24 hours later. .Analytical methods and techniques employed have 

 been described previously.^ 



After it was observed that glomerular filtration rate and renal blood flow were 

 depressed during the hypothermic period, an attempt was made to rule out the 

 blood pressure component by elevating the pressure back to the control levels with 

 vasopressor agents (norepinephrine or Aramine ) . It was reasoned that returning 

 blood pressure to the control levels would help to rule out the effect of hypotension 

 on glomerular filtration rate and renal l)lood flow\ 



The effect of renal ischemia on renal hemodynamics and water and elec- 



199 



