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Treating Orthostatic Intolerance in Chronic Fatigue Syndrome (ME/CFS)

Orthostatic intolerance (OI) is the inability to be vertical — sitting in a chair, or standing — without developing upleasant symptoms that improve when you lie down.

Survey data is limited but suggest that the vast majority of people with ME/CFS have orthostatic intolerance. However, many aren’t aware of it because testing isn’t done as standard, the symptoms can be hard to differentiate from other ME/CFS symptoms, and OI is much misunderstood, even among clinicians.

The simple act of rising from lying down or sitting requires a complex set of interactions involving the autonomic nervous system, blood vessels, muscle and heart to work smoothly to keep the blood from draining from out of our upper body into our lower body.

If this goes wrong, as it does in OI, not enough blood gets to the brain and the heart, and this produces symptoms. Some people feel lightheaded or dizzy or even faint immediately on standing, for example, but — importantly — others don’t. This latter group may take much longer — perhaps half an hour or more — to develop OI symptoms, but even then, may have other symptoms that force them to lie down before they feel lightheaded.

Broadly speaking, the first group have POTS (postural orthostatic tachycardia syndrome), in which standing causes an immediate, large increase in heartrate as the heart struggles to keep blood flowing to the brain and upper body; and the second group have NHM (neurally mediated hypotension), in which blood pressure drops after being upright for prolonged periods.

Dr Natelson, an ME/CFS specialist, has identified a ‘Postural Orthostatic Syndrome of Hyperventilation’ in ME/CFS patients.

OI is so common in ME/CFS that every patient ought to consider seriously whether they have it. The following pages provide more information.

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