Abstract
Recent work by Haggard 1 and by Shaffer and Ronzoni 2 has confirmed the idea, first advanced by Snow in 1848 but since often overlooked, that the absorption of ether in the lungs is a simple diffusion, and that the concentration of ether in the blood is therefore a function of the tension of ether in the lung air. The distribution ratio of ether between blood and air at 38° C. is about 15, according to which the tensions in air in equilibrium with the blood concentration required to produce anesthesia in dogs (110 to 130 mg. per cent) (Nicloux) are 19 to 23 mm. (2.5 to 3.0 vols. per cent) values which are much below the tensions commonly used with the Connell machine for the anesthesia of human patients. The concentration used by Boothby 3 for example, 51 mm. tension, if inhaled without dilution until the blood attains equilibrium would correspond to 293 mg. per cent in the blood, an amount which considerably exceeds the amount which causes respiratory failure (Nicloux, Ronzoni). The apparent discrepancy is due to the fact that the air inhaled by the subject is a mixture of that from the machine and of atmospheric air; the actual anesthetic tension in the air breathed is much below that delivered by the machine. White 4 has reported data on human patients which agree well with the data on dogs.
The present communication reports further data on the direct determination of ether in the blood of patients during surgical ether anesthesia. The results confirm the figures of the earlier workers on dogs, and indicate very similar range of anesthetic concentrations in human subjects.
For deep anesthesia a range of 110 to 170 mg. per 100 cc. was found; for light anesthesia 41 to 110 mg. per 100 CC. of blood.
Get full access to this article
View all access options for this article.