High-Salt Water­floating Effective For Stress And Pain Relief

Relaxation in large, sound- and light-proof tanks with high-salt water­floating ­is an effective way to alleviate long-term stress-related pain. This has been shown by Sven-Ake Bood, who recently completed his doctorate in psychology, with a dissertation from Karlstad University in Sweden.

The dissertation confirms what earlier studies have indicated: sleep was improved, patients felt more optimistic, and the content of the vitalizing hormone prolactin increased. Anxiety, stress, depression, and perception of pain declined. Those who took part in the research project all had some form of stress-related pain, and after only twelve treatments in the floating tank, their condition improved.

"Through relaxing in floating tanks, people with long-term fibromyalgia, for instance, or depression and anxiety felt substantially better after only twelve treatments. Relaxing in a weightless state in the silent, warm floating tank activates the body's own system for recuperation and healing. The stress hormone decreases, as does blood pressure. The findings confirm and reinforce our earlier studies on the effects of relaxing in a floating tank," says Sven-Ake Bood.

Many people experience improvement

His dissertation comprises four studies that all involve the treatment of pain and stress-related disorders with the aid of a floating tank. A control group that was not treated in a floating tank experienced no improvement in their health. After a period of treatment lasting a total of seven weeks, 22 percent of the participants in the floating group were entirely free of pain, and 56 experienced a clear improvement. Nineteen percent felt no change and 3 percent felt worse. And the effect persists after the treatment is completed. The research project has been under way for four years and has included 140 individuals, all with some form of diagnosis involving stress-related long-term pain.

Several types of pain can be affected

"The treatment method can be used for several groups, such as people with whiplash injuries, fibromyalgia, depression, and long-term stress-related pain. We can also see that a combination of treatment in a floating tank and traditional therapy can be effective. We are now moving on in our research and will be monitoring blood circulation in the capillaries, the oxygen uptake of the blood, and how the body's reflexes are affected," says Sven-Åke Bood.

This research is being carried out at the Human Performance Laboratory at Karlstad University and is being done in collaboration with the health authorities under the Värmland County Council. The studies included in the dissertation have been previously published in journals like the prestigious American publication International Journal of Stress Management.

 

Restricting environmental stimulation influences levels and variability of plasma cortisol

J. W. Turner Jr and T. H. Fine
Department of Physiology and Biophysics, Medical College of Ohio, Toledo 43699-0008.

Restricting stimulation from the environment has been shown to alter psychological and physiological states. The present study of 27 healthy subjects examines the effects of restricted environmental stimulation technique (REST) on plasma levels of cortisol and variability in plasma cortisol levels across repeated REST sessions. The REST environment consisted of a 1.2 X 1.2 X 2.4-m ovoid chamber containing 25 cm of saturated MgSO4 solution (sp gr 1.28) maintained at 34.5 degrees F. The buoyant supinely floating subject experienced a minimum of light, sound, and temperature awareness and spatial orientation. The non-REST environment was a cushioned reclining chair in a quiet dimly lit room. The 5-wk protocol consisted of four visits for blood sampling during a 2-wk baseline followed by eight REST or non-REST sessions, 40 min each, with blood samples taken on four nonsession days between sessions 5 and 8. Variability in plasma cortisol was expressed in terms of standard deviation. REST was associated with across-session decreases of 21.6% in plasma cortisol and 50.5% in plasma cortisol variability, whereas no changes in these measures occurred in non-REST. It is concluded that REST influences both static and dynamic aspects of adrenocortical function, possibly altering the feedback monitoring of plasma cortisol.

Effects of flotation therapy on relaxation and mental state

Emotional state improved
It has been reported that flotation therapy can improve the subject's emotion state.［4,7,8,9］ The results of this study show flotation could improve mood state and reduce anxiety and depression level significantly. The mechanisms may be as follows: ① Some psychologists have proposed that along with cognitive activities and emotions, every individual has their own ideal level of stimulation and arousal. Researchers studying flotation therapy believe that the usual level of stimulation encountered in modern society is too much for some individuals to handle. An environment of overwhelming stimulation leads to too much stimulation and information flooding the cognitive system of the individual. The individual cannot deal with all this information and stimulation effectively. So maladaptive reactions to the situation occur. If the individual is taken out of that environment and put into a less demanding one, these reactions could be avoided, reduced or eliminated. The person's whole mood status could be improved as well. ② According to the cognitive theory of emotion, emotion is affected by three factors: environmental, physiological and cognitive.［10］ During flotation therapy, external stimuli are extremely reduced so the stimulating events are few. So the mood is improved. ③ Some preliminary studies have suggested that flotation therapy may facilitate the release of endogenous beta-endorphin in the brain: beta-endorphin is a peptide that can induce euphoria state in human beings.［6］ ④ Flotation can induce deep relaxation. An individual feels comfortable, amused and pleasing when he or she is relaxed. ⑤ The effect of improving mood state may come from the collaborative operation of all the mechanisms.

Considering the results of this study and other studies, it can be suggested that flotation therapy may be helpful in the treatment of many psychological disorders and psychosomatic diseases. In hypertensive patients we have obtained good results through flotation therapy, but in patients with other psychological disorders or psychosomatic diseases must be tested in further studies and clinic works.

A previous study has shown that gender has no influence on the effects of REST. The results of this study shows that gender may influence the mood improving effect of flotation therapy. The improvement for women is better than that for men. This show that the flotation therapy may be better suited for females, but it needs further study and clinical work.

Vasorelaxation in Space

Compared with the ground-based upright posture, our data show that cardiac output is increased and the vasculature dilated and relaxed from the very onset of weightlessness and until at least a week into spaceflight. Systemic vasodilatation is most probably accounted for by chronic stimulation of blood pressure reflexes to prevent blood pressure from increasing. That central blood volume is expanded in space is indicated by the chronic increase in cardiac output and is supported by previous echocardiographic indications that weightlessness distends the heart chambers.^6–8

Because functional residual capacity is increased in space compared with that of the ground-based supine position, the increase in cardiac output is not only accomplished by the lack of pull of gravity on the blood column but also by expansion of the lungs and thoracic cage. Expansion of the lungs and thoracic cage creates a negative pressure around the heart and central vessels, which increases venous return and thus cardiac output. That this is the case is indicated by previous results from our group that esophageal pressure, which reflects changes in interpleural pressure, decreases more by acute weightlessness than central venous pressure does when referring to the 1-G supine position.⁸ Thus, central transmural venous pressure increases. This is probably the reason that Buckey et al⁶ observed a decrease in central venous pressure shortly into spaceflight despite the fact that the heart chambers were expanded. Such a condition, in which cardiac output is elevated and the lungs and thoracic cage simultaneously expanded, cannot be simulated on the ground. Thus, the lung–heart interaction is unique in weightlessness and important for maintaining cardiac output increased during prolonged spaceflight.

Our observation that systemic vascular resistance decreased in space might at first glance seem contradictory to observations by Watenpaugh et al,⁹ who reported that calf vascular resistance doubled after 4 to 12 days of spaceflight. However, these investigators used the ground-based supine position as reference. Therefore, their observations are in accordance with ours that systemic vascular resistance tended to increase in space compared with when the subjects were ground-based supine (Figure 2). However, this increase was much less than the doubling in calf vascular resistance observed by Watenpaugh et al.⁹ Therefore, it is likely that there are regional differences in the human circulation during spaceflight concerning degree of vasodilatation or constriction.

That cardiac output is increased and the circulation chronically dilated throughout a week in space is in contrast to the previously observed high levels of sympathetic nervous activity and renin-angiotensin-aldosterone during spaceflight.^10–12 Such activations of vasoconstrictor hormones usually reflect that the vasculature is constricted and central blood volume reduced. This was clearly not the case in this study. Therefore, whether the vascular sensitivity to sympathetic nervous activity and renin-angiotensin is reduced by weightlessness should be investigated in the future.

By comparing the data in Figure 1 with those in Figure 2, it is clear that the cardiovascular changes were attenuated throughout a week in space compared with the immediate 20-s responses. This attenuation over time could have been caused by a reduction in blood volume and by a smaller cardiac muscle mass.^13,14 It is noteworthy that cardiac output and systemic vascular resistance after a week in weightlessness adapt to a level in between that of the ground-based seated and horizontal supine positions (Figure 2). This is similar as to how renal responses to saline and water loadings adapt to spaceflight.^10,11 This level of adaptation in between supine and upright might constitute the natural operating point for control of circulation and fluid volume because humans constantly change position throughout life between the 2.

Possible Limitations
By using the foreign gas rebreathing method, we measured the pulmonary capillary blood flow of oxygenated blood, which is similar to cardiac output, when there is no significant physiological shunting of the blood in the lungs. Therefore, if different degrees of physiological shunting of blood had been present during the ground-based and in-flight conditions, this could have impacted our determinations of cardiac output. However, we have, in a previous study, observed that only when the arterial oxygen saturation is <95% can it lead to significant underestimations of cardiac output.¹⁵ It is not likely that this was the case in our healthy astronauts.

Because of the peripheral location in the finger of our blood pressure measurements, it could be argued that local vasoconstriction could have led to erroneous estimations of mean arterial pressure. However, we evaluated the continuous arterial pressure curves carefully for such artifacts. Another argument for error is that location of the hydrostatic reference point at the fourth intercostal space for the arterial pressure measurements was not correct. Location of the hydrostatic reference point is crucial when comparing ground based measurements with those during weightlessness because in this latter condition, all hydrostatic pressure gradients are abolished. We chose the fourth intercostal space as the hydrostatic reference point during the upright 1-G conditions because it is near to mid-heart level, at which brachial blood pressure is usually measured by the standard clinical methods.

Our data also have implications for understanding how gravity stresses patients with heart failure. Heart failure is characterized by a high sensitivity to the pull of gravity because the pumping capacity of the heart is reduced. Therefore, the vasculature is constricted to prevent blood pressure from falling. To alleviate the stress of gravity in compensated heart failure, we previously immersed heart failure patients into thermoneutral water (34.5°C). Compared with the upright seated control position, water immersion increased stroke volume index and decreased vascular resistance.^20,21 Thus, the circulatory condition in the heart failure patients improved. Because our results presented here from parabolic flights and spaceflight are in compliance with those of water immersion,^20,21 it is fair to conclude that gravity is a constant burden for heart failure patients and that it aggravates their condition. Therefore, a future purpose should be to investigate how to alleviate gravitational stress in heart failure.

Cardiovascular and neuroendocrine responses to water immersion in compensated heart failure

Conclusions. The results of this study demonstrate that central blood volume expansion in compensated HF elicits a reduction in systemic vascular resistance similar to that of normal control subjects, despite blunted forearm vascular responses. Concomitantly, release of AVP, renin, and NE is suppressed in HF patients to the same extent as in healthy subjects. Thus the baroreflex-mediated decrease in systemic vascular resistance and in release of vasoactive hormones is dissociated from the reflex control of forearm vascular beds and heart rate in compensated HF during WI-induced central blood volume expansion.

Perspectives. The increase in central blood volume improved cardiac performance, decreased sympathetic nerve activity and systemic vascular resistance, and suppressed the release of vasoactive and sodium- and water-retaining hormones in compensated HF. In fact, WI tended to normalize the levels of these variables. Therefore, the effects of WI on renal sodium and water handling in HF should be addressed in future studies. Such investigations may provide further insight into the pathophysiology of extracellular fluid volume control and may have implications for the treatment of HF.