INDICATIONS FOR CIRCULATORY STIMULANTS 73 



Blood Pressure May Be Increased. 1. By stimulating the 

 heart muscle, directly resulting in an increased tone, strength, and 

 irritability. (Digitalis and strophanthus partly in this way.) 



2. By constricting the blood vessels directly. It will readily be 

 Seen that if the force or nimiber of beats remain constant, any con- 

 striction of the blood vessels will lead to an increase of pressure, 

 ( Adrenaline acts, in this way. ) 



3. By constricting the blood vessels through a central nervous 

 action (digitalis, strychnine). 



4. By increasing the amount of fluid in the vessels, as in case of 

 intravenous, hypodermic, or rectal injections of physiological salt 

 solution. 



The Number of Heart Beats May Be Increased By. X. 

 Excitement or peripheral stimulation (alcohol, ether). 



2. Stimulation of the heart itself (caffeine). 



3. Direct depression of the inhibitory nerves, either centrally or 

 peripherally (belladonna). 



4. Reduction of blood pressure and indirect depression of the 

 inhibitory centers in the medulla (nitrites pai'tly so). 



5. Theoretically by stimulating the so-called accelerator mechan- 

 ism of the heart. 



INDICATIONS FOR CIRCULATORY STIMULANTS 



These agents are indicated in heart failure and vasomotor paresis 

 from various causes. In collapse, quickly-acting stimulants, such as 

 ammonia, alcohol and camphor, are often effective, when their admin- 

 istration is combined with the external application of heat and the 

 injection of physiological salt solution intravenously, subcutaneously 

 or per rectum. 



In shock (exhaustion of the vasomotor centers) the same measures 

 would not prove of the same benefit as intravenous injections of 

 adrenaline, which directly contracts the peripheral vessels, and in this 

 manner increases the tone in the medulla. 



Often circulatory stimulants with a constricting influence upon 

 the peripheral arteries, as digitalis, are useful in valvular disease 

 of the heart with simple dilatation, especially if dropsy is present. 

 A certain amount of tension is necessary to equalize the two circu- 

 lations, to keep the coronary arteries well filled and in this way 

 supply the necessary nourishment for the organ, and to promote 

 diuresis. 



Drugs of the digitalis group act favorably in cases of cardiac in- 

 competence, by diminishing the number of contractions, and in this 

 manner prolonging the diastole or period of rest for the organ. In 

 heart weakness of asthenic fevers the digitalis group is less efiicient 

 than alcohol, strychnine or caffeine. 



