Blood pressure and it's measurement (ILO/IMO Guidelines Appendix E I10-15)

Impairment and risks

The prime reason for blood pressure measurement in seafarers is to identify if it is raised and needs treatment to reduce the risk of later vascular events such as stroke and heart attack (see standards for these conditions). These are long term risks and blood pressure control to reduce them needs to reduce pressure to levels close to the normal range.

Very high blood pressure, whether untreated or treated, can have more immediate risks – stroke, eye disease, kidney damage resulting in incapacity for safe performance of duties and the need for emergency medical care.

Some of the older medications used to treat raised blood pressure may cause impairing side-effect in users.

Rationale and justification

• High blood pressure increases the risk of all forms of arterial disease, notably heart attack, stroke and peripheral vascular disease.
• The risks of arterial disease are increased in the presence of other risk factors such as smoking and diabetes.
• High blood pressure damages small blood vessels and this can lead to eye and kidney disease
• Blood pressure reduction by lifestyle changes or by medication reduces the risks of long term harm.
• The medications normally used to treat blood pressure rarely cause adverse effects that would impair fitness to work at sea. Some of the, now rarely used, older treatments can have significant adverse effects including an increased risk of fainting when standing up, reduced exercise tolerance and changes in mood.
• Blood pressure can be raised by exercise and by anxiety. In the setting of an employment medical it may be difficult to obtain a baseline value and so repeated measurement or the use of a monitoring device may be needed to obtain a valid result.

Clinical assessment and decision taking

The conditions of a medical examination on which a person's job may depend are those that are likely to lead to a raised blood pressure, especially if the seafarer knows that the observed level has been a cause of concern in the past. The major practical difficulty is obtaining a realistic resting level in the course of the examination.