BSAC

GENERAL MEDICAL
ANTICOAGULANTS AND DIVING

Anticoagulants are used to reduce the risk of pulmonary or systemic thrombosis or embolisation. Clearly some of the conditions requiring use of anticoagulants are in themselves an absolute contraindication to diving whatever treatment is given. This may be because of the serious nature of the disease itself or because even with the use of anticoagulants further episodes are not entirely prevented.

However, some people receiving anticoagulants will be entirely asymptomatic on treatment without any symptoms referable to the cardiovascular system. Obvious examples are individuals given anticoagulants for deep venous thrombosis/pulmonary embolism or because of the presence of prosthetic cardiac valves.

As far as scuba diving is concerned, in such individuals the only real risk to them is from haemorrhage, if we ignore the risk of any asymptomatic individual having further episodes of their presenting condition whilst anticoagulated. This however, assumes that adequate anticoagulation of that individual is maintained. It also assumes that there is no interaction between anticoagulation and the diving environment (e.g. altered partial pressures of gases). No such interaction is known, but it is known that decompression per se reduces platelet count and may even cause thrombocytopenia, which would aggravate any bleeding diathesis. (This is believed to result from platelet consumption by adherence to bubbles).

There are a number of situations which could cause haemorrhage when diving. Clearly trauma is likely to result in significantly more haemorrhage in an anticoagulated individual than in another individual. Whether auditory barotrauma will result in greater haemorrhage and hence produce greater residual problems, whether bleeds into sinuses and mask squeeze present greater problems in those anticoagulated and whether pulmonary barotrauma is more likely to result in major haemoptysis than in those not anticoagulated is unclear.

In addition, the post-mortem findings of decompression sickness include haemorrhage in the spinal cord. It is possible that anticoagulation will increase the risk of major haemorrhage and resulting serious neurological problems.

Furthermore, in anticoagulated individuals spontaneous haemorrhage or haemorrhage after trivial trauma may occur. Heavy nose bleeds are common. This could result in impairment of vision because the mask is filled with blood and confusion in diagnosis of pulmonary barotrauma by producing spurious haemoptysis. Cerebral haemorrhage is much less common but can cause neurological deficits which could be mistaken for diving related illness.
Overall the annual mortality and morbidity for sudden haemorrhage in those anticoagulated are 0.2% and 2% respectively.

The present policy of the BSAC is that use of anticoagulants are not permissible in new recruits but may be acceptable in established divers, provided no other contraindication exists and they appreciate and accept the risks involved. In such cases, decisions will be made on an individual basis and a limit on depth and number of ascents may be imposed to reduce the risk of spinal haemorrhage from decompression sickness.

This sheet is for information only and it is recommended that any case seen by a referee is referred to the Medical Committee.