Jenny King

A System of Cardiac Rehabilitation: Psychophysiological Basis and Practice

In the past, exercise therapy has been widely employed as the basis of cardiac rehabilitation, but reviews have not shown great benefit.1 Attention is now turning to models which help the patient to learn to defend the integrity of his internal milieu in the face of an external environment which is challenging, uncertain and rapidly changing. This discussion paper describes the Charing Cross Model, its psychophysiological basis, practice and implications for occupational therapy.

Hyperventilation in Cardiac Rehabilitation

Seventy-six out of the first 100 consecutive patients enrolled in a cardiac rehabilitation programme were considered to hyperventilate. The diagnosis was made on the basis of four or more clinical findings documented from the history, examination and electrocardiogram. Thirteen percent had an organic cause, the remaining 66 were found to hyperventilate with activity (39%), emotion (44%) or as a habit (17%). The cardiovascular effects of hyperventilation are outlined and a method of rebreathing training is explained. The opinion is expressed that hyperventilation is one of the maladaptive coping strategies commonly adopted by patients with coronary illness. Activity programmes are unlikely to be successful if it is not recognized clinically and treated.

Failure of Perception of Hypocapnia: Physiological and Clinical Implications

Hyperventilation causes hypocapnia and respiratory alkalosis and thereby predisposes to coronary vasoconstriction and cardiac arrhythmia. Diagnostic methods for use between episodes have not been established. In this study of 100 patients and 25 control subjects the resting end-tidal PCO2 (Pet CO2) levels and the results of a forced hyperventilation test did not show a significant difference between the groups. However the patients hyperventilated more profoundly in response to emotional stimulation, and were less aware of inappropriate breathing and hypocapnia. It is suggested that these differences should be accommodated in cardiac rehabilitation.

Breathing and Thinking: Unacknowledged Coronary Risk Factors

Health is a quality of life we enjoy when we can take a vigorous part in the world around us and yet keep the internal milieu in a balanced, orderly and stable condition. In varying degrees we are all vulnerable to loss of integrity of the internal self-regulating systems through such influences as the external environments changing too fast for our adaptive mechanisms, loss of control, lack of sleep, inadequate supplies of energy and information for the tasks on hand, and a want of social assets.

Confidence Intervals Enhance the Value of Research Publications

Traditionally, clinical research has been based on obtaining measurements from a sample of the population, subjecting the data to statistical analysis and drawing inferences about the whole population from which the sample was drawn. However, the value of research publications in this journal has been questioned (for example, Buttrey 1996, Jones 1996, King 1996, Minns 1996, Notley 1996): published papers have been disparaged as ‘increasingly unreadable’ and ‘full of unfathomable information’ (Minns 1996, p394). One of the reasons for this dissatisfaction may be the fact that analyses have focused upon statistical significance rather than upon clinical utility. The common statements, such as p<0.05 or p>0.05, convey no more than a portion of a study’s potential clinical findings and are likely to frustrate readers in search of the clinically useful information that can be obtained by employing a different statistical approach. For example, an occupational therapist wanting to learn the effect of an untested intervention on hand span would take care to choose an adequate sample, numbering perhaps 300 patients, and measure their hand span before and after the intervention. In such a fictitious sample the measurements might show that the intervention increased the mean span by 40mm, from 130mm to 170mm, deemed by statistical analysis, using a paired t test, to be a significant result (p<0.05). This p value tells the therapist that the difference made by the intervention is ‘real’ and unlikely to be due to chance. However, the accuracy of the extrapolation from the sample to the whole population cannot be gauged for, no matter how carefully studies are carried out, influences such as the size of the sample and the random variations within it will influence the outcome of the extrapolation. Furthermore, while the p value conveys information about statistical significance, it does not address the clinical value of the intervention directly. The purpose of this primer is to draw attention to a different statistical approach, namely the presentation of confidence intervals in addition to the usual tests for statistical significance. The confidence interval (CI) enables inferences to be drawn as to how well the sample represents the whole population and provides the information required for perceiving the clinical value of the findings. It also reveals statistical significance under certain circumstances. Extrapolating from sample to population

Book Review: Occupational Therapy in Psychosocial Practice, Bodies of Knowledge in Psychosocial PracticeOCCUPATIONAL THERAPY IN PSYCHOSOCIAL PRACTICE.BarrisR, KielhofnerG, HawkinsWatts J. Slack1988. 141 pp.

It would seem clear that, although search conferences have an intrinsic value in airing issues and bringing people together, their effectiveness will be limited unless some sort of action group is formed to follow through the agreed directions. In this way, a structure will develop that will not only support staff through the process of change but also help to solve problems as they arise. The requirement to report back to a further meeting of the stakeholders will motivate the action group to achieve its objectives.