A diving contractor experienced an incident where one of its divers suffered hypoxia due to breathing the wrong gas mixture.

Recently, a diver suffered a loss of consciousness at depth due to receiving a breathing mixture with an O₂ partial pressure well below that required. The rack operator immediately switched the diver to air, and the surface standby diver was deployed. After the diver was returned to the bell and the two divers were being brought up to the surface, the primary diver regained consciousness.

The contractor has instituted new procedures which require more than one individual to analyze breathing gas, prior to being placed online. Ensuring that all personnel engaged in the analyzing of breathing mixtures are thoroughly familiar with the tubing to each bottle valve and the spider / manifold to ensure proper identification of the which bottle is online and its proper content.

Additionally, follow up will be performed by the contractor’s senior management to address the issue of the gas vendor sending out improper bottle mixtures in the rack designated 86/14 (the mixture ordered for the job).

The contractor initiated all of the proper emergency and medical contingencies. Fully recovered, the diver has been cleared to resume work.

RECOMMENDATIONS
As diving operations begin to pick up, it is critical that contractors ensure that their personnel diligently analyze / verify the contents of gas cylinders. Perform these checks at the shop / dock, as well as prior to plumbing the bottles to the manifold. In short, a disciplined procedural check that is signed off by the person(s) performing the analyzing and the responsible supervisor should be instituted by the diving contractor. Never make assumptions.