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Role of biofeedback training in hypertension and stress.
Modern man lives in a constant state of anxiety which prevents him from facing the day-to-day problems of life. He strives to keep calm exteriorly but within, he is deeply disturbed. Nervousness and anxiety result in stress which affects his health adversely. The incidence of hypertension is rising throughout the world. In spite of its high prevalence and known clinical significance, very little is known about the etiology of hypertension. In nearly 10 per cent of the cases, hypertension is secondary to diseases of the kidneys, aorta, endocrine glands, etc., and is thus called secondary hypertension. In the other 90 per cent, no cause for hypertension can be detected and it is labelled as essential hypertension. In many of these cases, stress plays an important role in the causation of high blood pressure. It is observed that the urban populations have higher blood pressure levels than the rural populations.[1], [2], [9] This is probably because people in urban areas are under much more stress than those in rural areas. A higher standard of living, better educational facilities, higher incomes, a greater number of skilled occupations are associated with higher levels of blood pressure.[8] Most patients with hypertension are treated with drugs which have to be continued for life. The main drawbacks of drug therapy are the cost of the drugs and their side effects. Hence, any measures which could help in lowering blood pressure without the use of drugs are welcome. This is where yoga, biofeedback, and other relaxation techniques may provide an answer. This study was undertaken to find out whether the effects of stress can be modified by biofeedback training and relaxation.
Twenty hypertensive patients on conventional antihypertensive drug therapy were selected for this study. They were divided into two groups of 10 each. One group was treated with additional relaxation and biofeedback training and the other formed the control group. Treatment Group This group comprised of nine men and one woman. Eight patients had essential hypertension and two had renal hypertension. The average age was 56 years. The average duration of hypertension was 7.1 years. All these patients were on antihypertensive drugs. The average pre-drug-treatment blood pressure was 170/107 mm Hg. with a mean blood pressure (diastolic pressure + 1/3rd pulse pressure) of 128 mm Hg. With drug therapy, the average blood pressure came down to 158/103 (mean 121 mm Hg). At this stage these patients were given biofeedback training in addition to the drug therapy. Control Group This group consisted of 9 men and one woman. There were 9 patients with essential hypertension and 1 with renal hypertension. The average age was 57 years. The average duration of hypertension was 6.9 years. The average predrug-treatment blood pressure was 168/ 106 mm Hg. with a mean blood pressure of 127 mm Hg. The average blood pressure after initiation of drug therapy was 160/100 mm Hg. (mean, 120 mm Hg). All patients in both groups were given the cold pressor test and the Master's two step exercise test. Blood pressure was recorded before and after the test.. Recovery time was noted, Cold Pressor Test This was done according to the method of Hines and Brown.[6] After recording the blood pressure, the patient was asked to immerse one hand into ice-cold water (4°C) for 30 seconds, after which blood pressure was recorded again. The blood pressure reading was repeated every 1/2 minute till it came back to the initial level. Master's two-step test Master's two-step test consists of a predetermined number of trips over a set of 9 high steps. The test is adjusted to the sex, age, and weight of the patient. All our patients were given the single Master's two-step test for a minute and a half. The blood pressure was recorded before and after the test, and every half minute thereafter, till the B.P. returned to the initial level. Biofeedback training All patients in the treatment group were appropriately motivated to obtain their co-operation. They were seen three times a week, for half hourly sessions, for an average of 8 weeks. Their blood pressures were recorded in the standing, sitting, and supine positions, at the beginning and again at the end of each session. These patients were given training in relaxation and biofeedback methods. The patients in the control group also attended 3 times a week for 8 weeks. Their blood pressures were taken on arrival and again after half-an-hour's rest on a couch. These patients were not given any relaxation or biofeedback training nor were they told about their blood pressure levels. The training sessions were carried out in a room at a comfortable temperature. External noise was kept to a minimum but no attempts were made to make the room sound-proof. No meals were taken by the patients in the hour before the session. They were not allowed to wear tight clothing, a belt or even spectacles. During the training session, the patient lay supine on an examination couch, with his legs slightly apart and externally rotated at the hip joints, and with the hands about six inches away from the body, fingers slightly flexed. If the patient felt uncomfortable, he was given a pillow under his head. All were encouraged to lie flat and were, indeed, able to do so after a few training sessions. They were advised to keep their eyes closed. The patient was at first asked to breathe slowly and rhythmically, allowing the rhythm to take its effortless and natural pace. Having established this rhythm, he mentally goes over the different parts of the body in a regular sequence, usually starting with the toes and ending with the face, allowing each part to relax completely. During the whole session, the patient was connected to a biofeedback apparatus indicating galvanic skin resistance (G.S.R.) by means of a continuous sound signal. Changes in skin resistance provided a fairly reliable measure of the degree of relaxation. The cause of the changes in skin resistance is not completely known but sweat gland activity, which is proportional to the activity of the sympathetic nervous system, is one of the factors involved. As relaxation progresses, skin resistance increases and a drop occurs in the pitch of the audio signal. Thus, a correct response can be re-inforced, encouraging the patient to continue his efforts in the right direction. At the end of a session, each patient was told his blood pressure level before and after the session. Patients were encouraged to practise relaxation at home twice a day. After eight weeks' training, the cold pressor test and the Master's two step exercise test were repeated, in both treatment and control groups.
Subjective improvement was noted in most patients during the course of treatment. The patients reported that they felt better, slept better, and there was improvement in their other symptoms like headache, dizziness, fatigue and chest pain. There was a significant reduction in blood pressure in the treated group. In addition, the drug requirement was reduced by 33%. The results in both groups are shown in [Table 1]. Cold Pressor Test The results of the cold pressor test in both the control and the treated groups before and after treatment are shown in [Table 2]. As seen in [Table 2], the rise in both systolic and diastolic pressures was reduced after biofeedback training. The recovery time was also reduced. Changes in the control group were not significant. Exercise Test The results of the exercise test in both the control and treatment groups before and after treatment are shown in [Table 3]. This study indicates that the effects of stress are modified by biofeedback training and relaxation.
Stress plays an important part in the pathogenesis of hypertension. The resting haemodynamic changes in essential hypertension are similar to those occurring in a normotensive person during emotional stress.[4] These changes can also be produced by direct electrical stimulation of motor centres and regions of the hypothalamus.[3] It appears that repeated hypothalamic stimulation by emotional stimuli leads to sustained- high blood pressure. Since stress is a part of life it cannot be completely avoided. Hence it is important to change one's reaction to stress. The effects of stress can be modified by relaxation techniques like yoga, biofeedback training, transcendental meditation, autogenic training, zen, etc. Datey et al[5], demonstrated that shavasan" a yogic exercise which produces complete physical and mental relaxation, significantly lowers blood pressure in hypertensive patients. Patel and Datey[7] have shown a significant reduction in the blood pressure of patients treated with biofeedback training. They also showed reduction of blood pressure and symptomatic improvement after biofeedback training. Normally, sensory perception of outside events leads to a hypothalamic and a pituitary -response,- and this is reflected in a physiological manifestation by sweating, tachycardia, palpitation, high blood pressure, etc. With biofeedback training, these changes are perceived from moment to moment and the person is able to effect changes in the emotional and mental responses to inside events. This results in the modification of hypothalamic and pituitary responses, thus bringing them again towards the homeostatic level.
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