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Five-minute Practitioner: September 2008

Only got five minutes? Then just read these key points on: asthma, exercise in depression and eating disorders

Only got five minutes? Then just read these key points on: asthma, exercise in depression and eating disorders


The updated BTS/SIGN asthma guideline advises using spirometry, rather than peak flow, as the preferred measure of lung function. Spirometry allows clear identification of airflow obstruction and the results are less dependent on effort. It should now be the preferred test where available.

Good control of asthma is defined as: no daytime symptoms; no night-time waking due to asthma; no need for rescue medication; no exacerbations; no limitations on activity, including exercise, and normal lung function (FEV1 and/or peak flow >80% predicted or best).

Patients with difficult asthma should be assessed systematically to confirm or refute the diagnosis and identify the mechanism of persisting symptoms.

Inpatients should receive written personalised action plans as part of self-management education, given by an asthma specialist, before discharge. Plans should include written, personalised structured education; specific advice about recognising loss of asthma control, either through symptoms or peak flow recordings; and two or three action points to take if asthma deteriorates.

Exercise in depression

Several meta-analyses have produced robust evidence that exercise is effective as a monotherapy for depression. There is evidence that exercise is an effective therapy in all age groups. There is also some evidence that exercise provides additional benefit when combined with antidepressant drugs.

There are few conditions in which exercise is absolutely contraindicated. Recommending exercise to almost all depressed patients is likely to be of benefit and is unlikely to cause harm. Patients with many serious medical conditions are known to be at increased risk of depression, and a positive outlook may assist recovery. Exercise therapy in these patients may serve a dual role.

It would be reasonable to recommend three sessions of high intensity exercise per week to most depressed patients, with the absolute intensity tailored to the individual patient, taking into account their comorbidities. An energy expenditure of 17.5kcal/kg/week equates to three sessions a week of exercising to a heart rate of 145 beats per minute for about 30 minutes.

Exercise can reduce cardiovascular risk. And major depressive disorder is a risk factor for CVD, independent of traditional risk factors. Several hypotheses have been proposed to explain the mechanism of this link, including impaired arterial endothelial function, overactivity of the sympathetic nervous system, platelet hyperaggregability, and abnormal folate and homocysteine metabolism.

Eating disorders

It is common for patients to present to health professionals with symptoms that are secondary to an undiagnosed eating disorder. Many cases of eating disorder are hidden, and up to half of those meeting the diagnostic criteria for anorexia nervosa are unknown to their GP.

It is important to remember that not all patients with an eating disorder will be underweight. A significant proportion of those with bulimia nervosa or who suffer from binge eating will be of normal weight or even overweight.

The NICE guideline on eating disorders recommends the use of screening tools in primary care. Screening efforts should target: young women with a low BMI; patients of normal weight who reveal weight concerns; women with menstrual difficulties; patients with GI symptoms; patients with physical signs of malnutrition or repeated vomiting and children with poor growth.

Characteristics of the history that may be associated with increased risk include: excessive exercise with low weight; haematemesis; combined restriction of food and fluid; rapid weight loss or interruption of ritualised eating habits (eg during holidays or exams).

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