The value of intratracheal route of immunization with pneumococcus

Abstract

The ease which with gases diffuse through the respiratory mucosa is well known and is widely utilized in the practice of anesthesia. The absorption from the trachea, however, is not limited to gases. Thus, Mayer 1 found potassium ferrocyanide in the blood two to five minutes after its introduction into the trachea of animals. Moreover, even such substances which do not easily diffuse through other tissues may sometimes readily pass through the mucosa of the respiratory system. Thus, for instance, Colin introduced intratracheally 10 c.c. of 1 per cent. solution of curare (which is not absorbed from the intestine) killing the dog in 15 minutes. The rate at which fluids may be absorbed from the trachea is remarkable. Colin 2 describes an experiment in which he introduced intratracheally into a tracheotomized horse a continuous stream of warm (30°-35°) water at a rate of six liters per hour for 3 1/2 hours in succession without causing any noticeable discomfort to the horse. When at the end of the experiment the horse was sacrificed the observer could not detect any water in the trachea or bronchi, all water having been thoroughly absorbed.

In spite of this remarkable power of absorption, trachea was not generally employed as the route for the parenteral introduction of foreign substances in the experimental work until recently when Besredka₃ called attention to the fact that trachea constitutes as good and perhaps even a better site of introduction of antigen into the experimental animals than any other employed. During the summer of 1920 one of us had the privilege of personal acquaintance with the work of Besredka and it is this experience that suggested the possibility of utilizing the tracheal route for the purpose of productio'n of immunity to pneumococcus.