Apparatus for controlling temperature of catheter contents in cold environments

An apparatus was developed to prevent the freezing of catheter contents during blood sampling or liquid infusion into animals maintained at sub-freezing temperatures. The apparatus consisted of a larger, outer set of plastic and copper tubes and a smaller, inner set of tubes. The catheter was passed inside the inner set. Water circulated through the outer set kept the contents of the catheter inside the inner set from freezing. The apparatus was also useful for the rapid cooling of blood to a predetermined temperature while a sample was being withdrawn from an animal.