Gas intoxication: causes, symptoms, diagnosis, treatment

Various physiological (for example, O2, N, CO2) and non-physiological gases (for example, carbon monoxide) can cause a pathological condition during scuba diving.

[1], [2], [3], [4], [5], [6], [7]

O2 intoxication

Intoxication O usually occurs when breathing air, in which the O2 partial pressure reaches 1.6 atm, equivalent to a depth of about 200 feet. Symptoms include paresthesia, local convulsions, dizziness, nausea, vomiting and narrowing of the visual fields. Approximately 10% of patients develop generalized convulsions or fainting, which usually results in a drowning.

Nitrogen Anesthesia

When breathing compressed air at a depth of more than 30 m (> 100 ft), the increased partial pressure of N causes an effect similar to that of nitrous oxide ("fun gas"). Nitrogen anesthesia (nitrogen narcotic intoxication) causes symptoms and signs similar to the effects of alcohol (eg, intellectual and neuromuscular disorders, behavioral and personality changes). Violation of criticality can lead to drowning. Hallucinations and loss of consciousness can occur at depths greater than 91 m (> 300 ft).

As the state of most divers improves rapidly on ascent, the diagnosis is established clinically. Treatment includes an immediate but controlled ascent. Nitrogen anesthesia can be prevented by using helium to dilute O2 in deep water dives, since helium does not have N anesthetic properties. However, the use of pure helium-oxygen mixtures increases the risk of developing neurological disorders due to high blood pressure.

Poisoning CO2

Hypoventilation can be caused by inadequate respiratory movements, tight wet suit, physical overstrain, regulator dysfunction, deep immersion or contamination of supplied air with exhaled gas. Hypoventilation can increase the content of CO2 in the blood, cause dyspnoea and sedation. In severe cases, nausea, vomiting, dizziness, aching, rapid breathing, convulsions, confusion and loss of consciousness are possible.

A moderate degree of poisoning is suspected if the diver often develops diving-related headaches or decreases the amount of air used. Hypoventilation is usually resolved during ascent. In this regard, the analysis of the gas composition of the blood after immersion usually does not show an increase in the content of CO2. Treatment - a gradual ascent and refusal to dive or eliminate the cause.

Carbon monoxide poisoning

Carbon monoxide can enter the respiratory mixture of the diver if the intake valve of the air compressor is too close to the exhaust pipe of the engine or if the lubricating oil in the faulty compressor overheats and partially ignites ("flashes"), releasing carbon monoxide.

Symptoms include nausea, headache, general weakness, awkwardness and mental changes. In severe cases, cramps, fainting or coma may occur. The diagnosis is made by increasing the CO content in the blood (SONB); Pulse oxymetry is useless, as it usually shows a norm due to the fact that it does not distinguish oxyhemoglobin from carboxyhemoglobin. It is possible to examine the air supplied by a diver to the content of CO in it.

Treatment - inhalation 100% On a large flow, best through an unreversible mask, which reduces the half-life of SONB from 4-8 hours in indoor air to 40-80 min. In severe cases, treatment with hyperbaric O2 is indicated, which improves oxygenation of tissues and further reduces the half-life of SOS to 15-30 minutes.

[8], [9], [10], [11], [12]

Neurological High Pressure Syndrome

A poorly studied syndrome of neuromuscular and cerebral disorders can develop at a depth of 180 m (600 ft), especially when the diver is rapidly compressed while breathing a mixture of helium and oxygen. Symptoms include nausea, vomiting, small tremor, impaired coordination of movements, dizziness, fatigue, drowsiness, myoclonic twitching, stomach cramps and disorders in the intellectual and psychomotor sphere. Diagnosis is established on the basis of clinical data.