No abstract

A simple method of emergency underwater application of a nasal decongestant in divers to prevent diving-related accidents or even fatalities attributable to sequelae of middle-ear and sinus barotrauma of ascent was evaluated. Eleven military divers had to inject 1 mL of 0.02% methylene blue into a central venous catheter after having inserted the tip between their upper lip and the mask at 1 m depth in a pool. After injection, the head had to be reclined. Blue liquid flowing from a diver's nostril and a "bitter" taste sensation reported immediately after surfacing indicated successful application. All divers were observed to have had blue liquid flowing from the nostril of application, and one diver could not describe the taste. This method of underwater application of nasal decongestants may be useful for emergency prevention in divers, especially during covert operations. Underwater availability of the system in a special kit carried by divers would be required.

This study evaluated the feasibility of using the modified semi-closed circuit underwater rebreathing system (URS) LAR VII in connection with a laryngeal mask airway (LMA) as an expedient ventilatory adjunct in an operational setting. Fourteen combat swimmers, unfamiliar with this equipment, underwent cardiopulmonary resuscitation (CPR) mannequin training using these devices. Eighteen subjects, using a standard AMBU bag for ventilation, served as controls. Thirteen test persons were able to ventilate with the modified URS. Tidal volumes were significantly lower with the LAR VII/LMA than with the AMBU bag (medians, 350 vs. 800 mL). No significant difference was found in total time required for 10 CPR cycles (medians, 78 vs. 68.5 seconds). The median delay between recognition of cardiac arrest and first chest compression, however, was markedly increased with the LAR VII/LMA than with the AMBU bag (medians, 76.5 vs. 14.5 seconds). After proper training, divers might use a modified URS such as the LAR VII for CPR in connection with a LMA. Lower tidal volumes might prevent gastric inflation. Chest compression should be continued during LMA insertion.

Vitamins C and E did not reduce eustachian tube ventilatory function impairment overnight after the dive on day 1, suggesting no evidence of free radical-mediated toxicity affecting the eustachian tube or middle ear mucosa. Repetitive oxygen dives may cause tissue adaptation suggesting other than antioxidant defense mechanisms.