654 LEWELLYS F. BAKKEK 



8. The Experimental Production of Tetany in Human 

 Beings by Means of Forced Respiration and the 

 Occurrence of Tetany in Pathological Hyperpneas 



An important paper has recently appeared, in which the proof has 

 been brought that tetany can be experimentally produced in human beings 

 by means of forced respiration. Grant and Goldman (1920), working in 

 Professor Erlanger's Department of Physiology in Washington University, 

 St. Louis, have brought this proof through a series of most carefully con- 

 ducted experiments. 



Having noticed, in persons subjected to a period of forced respiration, 

 that the urine collected at the end of the period was cloudy, owing to 

 alkalinity and the precipitation of phosphates, and surmising that the 

 overventilation, through removal of CO 2 from the blood, had tended to 

 make the blood more alkaline, and that, as a result of this, alkali had been 

 excreted by the kidneys, in order that the hydrogen ion concentration in 

 the body might be kept constant, these investigators undertook a further 

 series of experiments to test the validity of their conjecture. 



In some 23 experiments (exclusive of one control), the subject, lying 

 on his back, breathed as deeply as possible, at the rate of about 14 times per 

 minute (in time with a metronome). Symptoms of tetany developed in all 

 the experiments within a short period (varying from 15 to 60 minutes), 

 the diagnosis being based upon the presence of carpopedal spasms, Chvo- 

 stek's sign, Trousseau's sign, Erb's phenomenon, and, in one instance, a 

 tetanic convulsion. 



The attention of Grant and Goldman was drawn to the occurrence of the 

 tetany in their very first experiment. The subject, taking 15 deep breaths 

 per minute, felt tingling in his fingers at the end of ten minutes. Five 

 minutes later the muscles of his face felt stiff and he experienced some 

 difficulty in articulation. In their second experiment (another subject) 

 tingling of the tongue also developed, and at the end of 40 minutes, on in- 

 flating of the curl' for a blood pressure determination, the typical "obstet- 

 rical hand" of tetany was involuntarily assumed. 



The two subjects, who appear to have been the two investigators them- 

 selves, were found on repeated experiments to differ somewhat in their 

 reactions. In the one, spasticity of the facial muscles developed after 

 breathing deeply for about ten minutes, when Chvostek's sign became 

 easily elicitable. On continuation of the forced respiration, the spasticity 

 in the facial domain increased until spontaneous contractions that puck- 

 ered the lips and made articulation difficult occurred. Meanwhile, numb- 

 ness and tingling had appeared in the hands, and a little later carpal spasms 

 spontaneously set in. After cessation of the forced respiration, Chvostek's 

 sign remained positive, a slight reaction being obtainable as long as twenty 



