The experiments upon human subjects verified the results secured in the experiments upon animals. The first series of experiments upon human subjects were planned to determine the effect of stimulation, inhibition, and an artificial lesion upon systemic blood pressure. It should be remembered that the experiments upon animals indicated the following facts: The artificial lesion in the splanchnic area causes a dilatation of the intestinal vessels, a lowering of the systemic blood pressure, a relaxation of the gastric and intestinal walls, and the accumulation of gas in the stomach and intestines. Mechanical inhibition in the same area produces the same results in less marked degree. Mechanical stimulation in the splanchnic area causes increased peristalsis, decreased caliber of the blood vessels, increased systemic blood pressure, and the absorption of whatever gas may be present in the stomach and intestines. Mechanical stimulation of the tissues near the thirteenth and fourteenth vertebrae causes a rise of blood pressure and a contraction of the arterioles in many parts of the body, and an increased heart action, by the effects of the increased action of the supra-renal capsules. It is needless to say that these experiments could not be repeated upon human beings. But equivalent results were secured by use of harmless methods. The first series of experiments upon human subjects were devoted to the determination of the effects of stimulation, inhibition, and the artificial lesion upon blood pressure. Inhibition was secured as follows: The hands of the experimenter were placed under the subject in such a manner that the fingers rested between the transverse processes of the vertebrae to be affected. In this case the eighth to the tenth thoracic vertebrae were selected. The fingers supported the subject during the experiment. The inhibition lasted for from three to five minutes. The exact time depended upon the information given by the sense of touch of the experimenter. He was able to recognize a change in the tension of the tissues when the inhibition had been effective. (Note A.)
After the inhibition was given the blood pressure was again taken. If the subject were in normal condition, it was invariably found that the inhibition had decreased the blood pressure. In some instances, the fall in pressure amounted to fifteen millimeters of mercury. In others, the fall was less pronounced. An average of the effects observed upon fifteen subjects showed a decrease of eight millimeters of mercury. This lowered blood pressure was accompanied by a marked feeling of sleepiness on the part of the subject. This sensation made the elimination of psychical effects more easy than it might have been. None of the tests here mentioned were made during sleep, though the subjects often slept after the experiment was concluded. The nature of the reflexes during sleep is being studied in connection with investigations into the physiology of the nervous system. Mental activity was lessened in every instance of decreased blood pressure. In some instances, the subject, who thought himself normal, was found to suffer from contracted and hypersensitive muscles in the splanchnic region. The inhibition of these areas then relaxed the muscles, and often in these cases the effect of the treatment was to increase the blood pressure. The mechanics of the procedure are evident. The abnormally contracted muscles had been exercising an inhibition for some time, and the mechanical inhibition simply relaxed the muscles and permitted the normal nerve impulses to be unaffected. The rise of blood pressure indicated a return to the condition normal to the individual.
The artificial lesion was produced in eight cases. Lesions affecting the tenth thoracic nerves decreased the blood pressure most greatly in all the subject s examined. Other thoracic lesions produced a variable decrease in the blood pressure. Lesions affecting the twelfth thoracic nerves caused a slight fall of flood pressure, but we were unable to demonstrate any effect directly referable to change in the supra-renal activity by this maneuver.
The effects of splanchnic stimulation upon the blood pressure were then tested. About twenty people were subjects for these tests. The experiment was conducted as in the preceding series. The subject lay quietly upon the treating table until all pulse changes had ceased. The normal resting blood pressure was then taken. Stimulating manipulations were then given in the chosen area. These movements were made by placing the fingers of either hand, or both, over the tissues between the transverse processes of the vertebrae subjected to experiment, and then making quick, forceful vibratory movements. In this work, also, the sense of touch of the operator is the only test of the efficiency of the movement during the time it is being given. The stimulating movements were given for one or two minutes, according to requirements of the case, as recognized by the occurrence of certain changes in the tissues which are perceptible to the touch but not easily described. The efficient stimulation of the tissues caused them to feel somewhat “toned up,” or “more lively,” as some operators have expressed it. The subject usually is unable to recognize in any exact degree the nature of the effects being produced. The effects of stimulation near the tenth thoracic vertebra cause a rise in blood pressure up to twenty millimeters. The average rise of blood pressure so produced is ten millimeters. In every case subjected to experiment by a competent operator, some rise has been observed. Not every operator is able to secure results at the first effort, however. Stimulation of the tissues near the twelfth thoracic vertebra caused a very great rise in the blood pressure, and also, in almost all of the subjects, a perceptible whitening of the conjunctivae. The force of the heart beat was increased also, but not its rate. These effects were, in the light of the experiments upon animals, referred to an increased secretion of the supra-renals. The effects of this stimulation were more transient than were the effects of the stimulation of the other tissues. Stimulating manipulations which caused a rise of blood pressure usually caused also a sense of well being, an increase of mental activity, especially of the powers of association, and a sense of alertness. This effect was not very pronounced in some cases, and in a few was not noticeable at all. It is evident that no weight could be given to an answer to a direct question along such lines, so the question was given merely as “How does it make you feel?” or some such question. In many instances the mental effect was the most conspicuous subjective effect of the stimulation. Stimulation of the tissues near the twelfth caused the greatest rise in blood pressure, and this stimulation often increased the secretion of urine. In the first experiments, this point was not mentioned, but in later tests, it was found that this effect was produced in nearly all cases. Stimulation of the tissues near the tenth thoracic seemed to increase peristalsis. This was determined by the sounds heard by the use of the stethoscope. Persons who were subjected to this experiment afterward spoke of an increased hunger and thirst. This increased hunger was noticed in some cases where the subject of the experiment was not quite in a normal condition. In all cases, the effects of the stimulation were annulled by too long application of the stimulating movements. If the movements were very heavy and were continued for even five minutes, the symptoms of exhaustion of the centers appeared, and the effects were similar to those observed after the production of the artificial lesion.
Stimulating movements were efficient only when the deeper tissues were affected. Superficial manipulations may produce some effects, even stimulation of the skin alone produced perceptible effects in some cases, but the work which secured the most conspicuous effect was that applied to the tissues between the transverse processes of the vertebrae, and which affected the very articular surfaces of the vertebrae, and, in the thoracic region, the articular surfaces of the ribs. Note A.—In our investigations in the Pacific College laboratories we found the average blood pressure much lower than is that given in the text books upon physical diagnosis. This is probably due to the character of the climate in Los Angeles. Statistics in text books are compiled in the laboratories of medical and scientific colleges in eastern states, or those of the middle west, where the climate is subject to sudden and ferocious changes. Therefore, the blood pressure I kept very much higher than is needful in this equable climate with its sea-level air pressure. Note B.—A certain delicacy of touch, acquired only through experience, is essential to the perception of these tissue changes. This delicacy of perception is essential to the success of an osteopath, and every student of osteopathy should begin the education of this touch sense at the very beginning of his course. |