Professional divers use such a calculation only as a rough guide to give new divers a metaphor, comparing a situation they may be more familiar with.Reported signs and symptoms are summarized against typical depths in meters and feet of sea water in the following table, closely adapted from Deeper into Diving by Lippman and Mitchell:

Causes
The cause of narcosis is related to the increased solubility of gases in body tissues, as a result of the elevated pressures at depth (Henrys law). Modern theories have suggested that inert gases dissolving in the lipid bilayer of cell membranes cause narcosis. More recently, researchers have been looking at neurotransmitter receptor protein mechanisms as a possible cause of narcosis. The breathing gas mix entering the divers lungs will have the same pressure as the surrounding water, known as the ambient pressure. After any change of depth, the pressure of gases in the blood passing through the brain catches up with ambient pressure within a minute or two, which results in a delayed narcotic effect after descending to a new depth. Rapid compression potentiates narcosis owing to carbon dioxide retention.A divers cognition may be affected on dives as shallow as 10 m (33 ft), but the changes are not usually noticeable.
Throughout the brain, the placement of these neurons is normally quite precise. If this system doesnt work exactly right, neurons can develop outside their appropriate areas. If this happens then the firing or circuitry of the brain is not right, and an abnormal, epileptic circuit can result. Treatment
Identification of the underlying cause plays an important role in treatment. Brain abscesses or tumors can be—at least temporarily or partially, if not fully and permanently—surgically treated and chemotherapy and/or radiotherapy is given to the patient. If seizures do continue, various anticonvulsant medication regimens that can be tolerated by the patient can be tested and if need be, administered, either orally, or in emergency conditions such as status epilepticus after tonic-clonic (grand mal) seizures, intravenously. If stroke or other similar, transient disorders occur (cerebrovascular accident, or transient ischemic attack, TIA), then neurological imaging of the affected lobes or hemispheres of the brain can be performed (CT, MRI, PET, etc.) and, if not absolutely contraindicated, antithrombolytic therapy might be given if it can be tolerated due to the seizures; if a hemorrhagic stroke has occurred and surgery can be performed to cauterize the vessel or otherwise stop the bleeding, it will be attempted if it can be done safely. References


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