Symptoms of Caisson's disease are 'the bends' - pain near the joints - and 'the staggers' - vertigo and difficulty breathing. 'The chokes' occur in very severe decompression sickness and are fatal.
- when the diver ascends the gas that has dissolved in the tissues will come out of solution to form bubbles of gas in the tissues and in the blood vessels
- these bubbles are then transported to the lungs where, in most cases, they are filtered out - this is the process of decompression
- if the bubbles cause medical problems for the diver, then the diver is said to be suffering from decompression illness (DCI) which used to be known as caisson disease
- gases that are chemically unreactive as far as the body is concerned (e.g. nitrogen, helium and neon) are sparingly soluble in blood - also oxygen, when breathed at high partial pressures, can cause problems on ascent.
- there are three types of DCI recognised - "the chokes", "the staggers" and "the bends"
- "the chokes" - this was seen in caisson workers - if the decompression procedure was inadequate, then the blood of the workers literally frothed - this was called "the chokes" and proved to be rapidly fatal unless rapid recompression took place
- "the staggers" - vertigo and difficulty breathing are dominant features - in this situation the decompression was not so provocative so as to provoke "the chokes" - "the staggers" might lead to severe impairment of the nervous system or death
- "the bends" - commonest form of DCI and less severe than "the chokes" or "the staggers" - moderately or severe limb pain
During the acute episode there may be respiratory and circulatory collapse, neurological damage and death.
Edge (1) has described an more exhaustive list of possible clinical features of DCI (1):
- pruritic mottled skin rash;
- vague limb discomfort ("the niggles");
- moderate or severe limb pain ("the bends");
- feelings of being abnormally tired or exhausted;
- abnormalities on psychometric testing;
- limb weakness or paralysis;
- parasthesiae;
- vertigo;
- headache;
- vomiting;
- abdominal pain;
- visual problems;
- collapse, hypotension, loss of consciousness
Bone necrosis may result from capillary obstruction by gas bubbles and changes in marrow fat.
About 50% of cases of DCI will exhibit signs and symptoms within 1 h of surfacing, while 90% will present within 6 h of surfacing
- in a few cases, the time interval has been of the order of days
- a diver could be thought to be drunk or under the influence of drugs when he presents to the GP's surgery or police station. If in doubt as to whether the diver is suffering from DCI then advice should be sought from diving medical experts
Notes:
- manifestations of DCI are considered to be predominantly due to a high inert gas load in the tissues
- gas may form within the tissues as a result of insufficiently rapid washout of excess dissolved inert gas during the ascent
- the gas may then go on to form bubbles within the tissue and venous circulation. Once in the venous circulation, these bubbles may be detected in the right atrium and ventricle by the use of 2D Doppler echocardiography
- in the vast majority of cases, these bubbles are clinically "silent" and are removed by the pulmonary circulation without causing any symptoms of DCI. Thus, although quantification of the bubbles is useful for elucidating the pathophysiology of DCI, it is not useful in the assessment or in the management of divers with DCI
Reference:
- 1) Edge CJ. Recreational diving medicine.Current Anaesthesia Critical Care 2008; 19 (4): 235-246.
- 2) Knauth, M. et al. Cohort study of multiple brain lesions in sport divers: role of a patent foramen ovale. BMJ 1997; 314: 701-5.