Spinal-cord injury can negatively affect blood pressure, but there are remedies.
Orthostatic hypotension (OH) is defined as a decrease in systolic blood pressure of 20 mm Hg or a decrease in diastolic blood pressure of 10 mm Hg within three minutes of standing when compared with blood pressure from the sitting or supine position.
A normal hemodynamic response to changes in posture requires normal function of the cardiovascular and autonomic nervous systems (the sympathetic system – so-called “fight or flight” and the parasympathetic). Standing results in blood pooling of approximately 500 to 1 000 mL in the lower extremities and vessels in and around the gut. This initiates an increase in sympathetic outflow, which through various methods increases pressure in the peripheral vasculature, thus limiting the decrease in blood pressure drop.
Common symptoms of OH include:
- Blurred vision
Less common symptoms include: syncope, dyspnoea and chest, neck or shoulder pain.
Causes include dehydration or blood loss, neurological conditions, disorders of the cardiovascular or endocrine systems, and several classes of medications.
In spinal-cord injury (SCI) OH is common, especially in the acute phases but should improve over time. However it can sometimes be so severe and persistent that quality of life is severely affected. The following conservative measures are used to reduce the symptoms:
Elasticated lower limb stockings – This helps to return the pooled blood to the heart;
Adequate hydration and salt intake – Often SCI patients have salt deficiency which exacerbates the effects of OH;
Graduated mobilisation – Mobilising slowly from lying to sitting will help in the maintenance of BP;
Elasticated abdominal binders; and
Avoidance of diuretics such as alcohol and caffeine.
After a large meal blood pressure can drop even in non-injured persons – this is known as post-prandial hypotension. Avoid it by eating regular smaller meals.
If all else fails and low BP persists, medication is required. There is really only one drug available in SA to treat OH: Florinef – a cortisone-type drug. However, in particularly difficult cases, another drug is available on special application to the Medicines Control Council. If you suffer from OH and have used all the conservative means to manage this and still suffer severe symptoms, speak to your doctor about medications that can help.
Dr Ed Baalbergen is the medical officer at the Vincent Pallotti Rehabilitation Centre (Cape Town) and is a member of the International Spinal Cord Society and the Southern African Neurological Rehabilitation Association. email: email@example.com