1907.] Rate of Elimination of Chloroform from the Blood. 589 



For the sake of argument, we will assume that during recovery from 

 anaesthesia the blood circulates in the body, and that no exchange of chloro- 

 form takes place between the blood and tissues. Under such conditions it is 

 clear that, given a steady elimination at the surface of the lungs, the amount 

 of chloroform in arterial blood would be constantly less than in venous, and 

 this difference would probably be a decreasing one. During the initial rapid 

 elimination, this difference would conceivably be marked and easily detectable 

 by experiment ; but in the later stages, where the elimination is slow, the 

 difference would possibly lie within the errors of experiment. But during 

 recovery from anaesthesia there will be superimposed on this simple con- 

 ception of the circulation a discharge of chloroform from the tissues into the 

 venous blood. If this took place steadily, it would tend to increase the 

 difference between arterial and venous blood. The problem, however, appears 

 to be more complex. First of all, the blood comes from regions such as the 

 muscles, viscera, etc., which are probably not charged to any great extent 

 with chloroform, compared to what is believed to be the case for the central 

 nervous system. The nerve centres are differently affected, and doubtless 

 discharge at different rates, as the evidences of their activity or paralysis 

 appear and disappear irregularly. Further, it is not inconceivable that 

 during the elimination one region may be discharging chloroform while other 

 cell-districts are relatively inactive in this respect, or even actually con- 

 tinuing to absorb chloroform. The question will be further complicated in a 

 very marked degree by the nature of the respiration at any moment, for the 

 depth and frequency of respirations naturally govern the elimination at any 

 particular moment. On the whole, therefore, we should expect the 

 chloroform-content of venous blood to be higher than that of the arterial, but 

 this difference would be slight in the later periods of elimination. In actual 

 experiments one would expect the result would depend markedly on the 

 particular source whence the venous blood was taken. A comparison with 

 Curves A and B shows a general similarity in the rate of elimination both in 

 the case of arterial and venous blood. Both curves show irregularities in the 

 rate. In Curve C, the chloroform-content of arterial blood is contrasted with 

 the general venous blood of the body (sample taken close to the heart). At 

 the moment of cessation of respiration, the arterial blood is markedly higher 

 than the venous, but after regular respiration is established, the two curves are 

 practically identical, the difference being within the errors of experiment. 



The work has been carried out with the help of a grant which was made 

 to us by the Government Grant Committee of the Eoyal Society, for which 

 we now express our thanks. 



