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Beyond Biofeedback – Drs Elmer and Alyce Green

Decrease of blood-vessel diameter due to muscular tension in the smooth muscles of blood-vessel walls causes pressure to go up. If these smooth muscles are continuously activated by abnormally high sympathetic nervous tension, the effect is as though blood-vessel diameter had been mechanically reduced by internal deposits. Patients who suffer from "psychosomatic high blood pressure"-high blood pressure induced by excessive vasoconstriction due to improper response to some kind of life stress-often show a highly variable pressure. Their blood pressure is said to be labile-that is, it rapidly goes up and down in accordance with the patient's mood and the stresses of life.

Patients with blood vessels blocked by deposits are relatively non-labile. Blood Pressure often remains high regardless of the patient's mood, and is not easily controlled by drugs. Labile hypertensives, however, are easily affected by drugs that alter smooth muscle tension. Unfortunately, these drugs affect smooth muscles all over the body. This is one of the side effects that often become so objectionable that physicians hesitate to increase dosages to the amounts necessary to control blood pressure.

Before turning to the research and clinical findings, it is useful to consider what systolic (pulse pressure) and diastolic (pulse relaxation) mean. When the doctor pumps air into the arm cuff, pressure builds up to the point where certain large arteries are squeezed flat and no blood flows through them into the arm. Using a stethoscope pressed against the arm next to the cuff, the doctor can hear the swish-swish of blood through the flattened arteries cease. Then he gradually allows the air pressure in the cuff to drop, watching a pressure indicator (called a manometer) and listening for the heartbeat sound associated with the opening of the artery. At the instant the pulse can be heard in the stethoscope, the doctor reads the manometer. This is the systolic pressure, the pressure resulting from the contraction of the heart.

As the doctor continues lowering the air pressure in the cuff below the systolic pressure point, a pulse sound remains audible until the cuff pressure is so low that it does not significantly compress the artery wall. When that happens, the sound disappears, and the doctor again notes the manometer reading. This is the diastolic pressure.

 It is obvious that with a stiff and inflexible artery, a good deal more air pressure is needed before the artery is flattened to the point where blood will not flow. Similarly, an artery that is highly constricted because of tension in smooth muscles will not easily flatten, and will also take considerably higher air pressure before blood-flow sounds are stopped. Diastolic pressure also is higher in a nonelastic, thickened artery and somewhat higher in a vasotense artery. Diastolic pressure, however, is not as variable as systolic pressure. Physicians generally view the systolic reading as possibly including a significant stress component, while diastolic reading is generally considered to be indicative of a physiological state rather than an emotional-response state. This is what gave rise to the idea that the diastolic state would not respond in any significant way to efforts at self-regulation, though systolic pressures might. With biofeedback training or meditation practices, however, it has been found that both systolic and diastolic pressures can be reduced.

Before we report on our own exploratory work in blood-pressure control, let me mention two earlier scientific studies. In the study by Brener and Kleinman, male college-student subjects watched a manometer on which systolic blood pressure obtained from a finger cuff was continuously displayed. (The finger cuff is used in the same way as an arm cuff but is considerably more comfortable.) The subjects were instructed to lower the pressure. Subjects were given twenty 50-second trials during each of two sessions and succeeded in lowering blood pressure 16 mm Hg (millimeters of mercury) during the first session and 12 mm Hg during the second session. Members of a control group were informed of the response being measured and were instructed to watch the feedback display, but were not instructed to lower their blood pressure. They showed no change in blood pressure during trials.

Schwartz and Shapiro reported the application of feedback technology in a study of systolic pressure in seven patients diagnosed as having essential hypertension (high blood pressure with no known cause). All patients were maintained on their prior drug schedules. Seven were given from five to sixteen adaptation sessions in a quiet, resting condition until there were no further systolic-blood-pressure decreases over five consecutive sessions. In other words, they were allowed to relax and adapt to the situation until their blood pressure maintained a constant level during five consecutive sessions. Then they received daily feedback sessions for decreasing systolic pressure until reaching the criterion of "no further decreases in pressure in five consecutive training sessions."

Five of the seven patients showed decreases in systolic pressure of 34, 29, 16, 16, and 17 mm Hg in differing numbers of sessions for each subject before reaching the criterion, respectively 33, 22, 34, 31, and 12 sessions. Two of the seven patients showed no significant decreases. Schwartz and Shapiro suggested that blood-pressure feedback combined with other techniques designed to lower sympathetic activity (neural activity that causes constriction in smooth muscles in blood-vessel walls) might be a fruitful approach in blood-pressure control.