Diving with High Blood Pressure

1. What are the risks?
High blood pressure can increase the strain on the heart and blood vessels when diving. Blood pressure tends to increase underwater, particularly if the dive is physically or psychologically demanding. In divers with high blood pressure there is a risk that this extra strain on the heart can cause fluid to build up in the lungs (pulmonary oedema) and this can cause difficulty breathing or even loss of consciousness. It can be difficult to tell the difference between this and other causes of breathlessness such as burst lung (pulmonary barotrauma), which makes emergency treatment more complicated. The other risk of high blood pressure is the treatment, since this can slow the heart (if taking beta blockers, such as atenolol) or lower the blood pressure too much causing dizziness or blackouts.

2. Can I dive with high blood pressure?
Yes, if your blood pressure is controlled with treatment which will not affect your fitness to dive. If your blood pressure on treatment is less than 160/90 and there is no clinical evidence of damage to the heart, kidneys or blood vessels then you can dive if your medication is listed as allowable:

Allowable medication

Medication requiring further assessment:

Diuretics – such as bendrofluazide

Beta blockers – such as atenolol or bisoprolol

Class II calcium channel blockers- such as amlodipine or felodipine

Class I or III calcium channel blockers – such as diltiazem or verapamil

Alpha blockers – such as dozasosin

Direct vasodilators – such as hydralazine

Angiotensin converting enzyme inhibitors – such as enalapril or lisinopril

Central alpha blockers – such as clonidine or methyldopa

Angiotensin II antagonists – such as losartan, irbesartan or valsartan

If you are taking more than two allowable drugs (including combination preparations) for control of your blood pressure, or if you are taking medication in the second column (above) then you should be assessed by a medical referee before diving. Such assessment may include an exercise test to prove that your heart rate is not limited by the medication, and an ultrasound scan of the heart (echocardiography) to make sure that the heart muscle has not been affected by the blood pressure.

3. Where can I get more information?
Contact your GP in the first instance, or ScotSAC head office (The Cockburn Centre, 40 Bogmoor Place, Glasgow, G51 4TQ. Tel/fax 0141 425 1021) who will be able to give you details of a local medical referee.