17-11.4 Chemical Injury. The term chemical injury refers to the introduction of a caustic solution from the carbon dioxide scrubber of the UBA into the upper airway of a diver.
17-11.4.1 Causes of Chemical Injury. A caustic alkaline solution results when water leaking into the canister comes in contact with the carbon dioxide absorbent. When the diver is in a horizontal or head down position, this solution may travel through the inhalation hose and irritate or injure the upper airway.
17-11.4.2 Symptoms of Chemical Injury. Before actually inhaling the caustic solution, the diver may experience labored breathing or headache, which are symptoms of carbon dioxide buildup in the breathing gas. This occurs because an accumulation of the caustic solution in the canister may be impairing carbon dioxide absorption. If the problem is not corrected promptly, the alkaline solution may travel into the breathing hoses and consequently be inhaled or swallowed. Choking, gagging, foul taste, and burning of the mouth and throat may begin immediately. This condition is sometimes referred to as a "caustic cocktail." The extent of the injury depends on the amount and distribution of the solution.
17-11.4.3 Management of a Chemical Incident. If the caustic solution enters the mouth, nose, or face mask, the diver must take the following steps:
1. Immediately assume an upright position in the water.
2. Depress the manual diluent bypass valve continuously.
3. If the dive is a no-decompression dive, make a controlled ascent to the surface, exhaling through the nose to prevent overpressurization.
4. If the dive requires decompression, shift to the EBS or another alternative breathing supply. If it is not possible to complete the planned decompression, surface the diver and treat for omitted decompression as outlined in paragraph 17-10.6.
Using fresh water, rinse the mouth several times. Several mouthfuls should then be swallowed. If only sea water is available, rinse the mouth but do not swallow. Other fluids may be substituted if available, but the use of weak acid solutions (vinegar or lemon juice) is not recommended. Do not attempt to induce vomiting.
A chemical injury may cause the diver to have difficulty breathing properly on ascent. He should be observed for signs of an arterial gas embolism and should be treated if necessary. A victim of a chemical injury should be evaluated by a physician or corpsman as soon as possible. Respiratory distress which may result from the chemical trauma to the air passages requires immediate hospitalization.
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