Report on Decompression Illness, Diving Fatalities and Project Dive

GlossaryRepresentative SampleA group selected from a population for testing that reasonablyrepresents the characteristics of the population.Residual SymptomsSymptoms remaining at the conclusion of treatment. Mayrespond to additional treatments, be refractory to furthertreatment but eventually resolve spontaneously, or permanent.Resolution of SymptomsSymptoms resolving (disappearing) after appearance.Resolution may be spontaneous or in response to treatment.Safety StopA halt in the planned ascent to the surface (usually for 3-5minutes at 10-20 fsw / 3-6 msw) intended to reduce risk ofdecompression injury. A safety stop is not a decompressionstop required by tables or a dive computer.SERF (Scuba Epidemiological <strong>Report</strong>ing Form)A new injury recording system for DAN that replaces theDIRF. It emphasizes collection of recorded dive profiles.(See page 64.)Shallow-Water BlackoutUnconsciousness resulting from hypoxia and compounded bysurfacing at the end of a breath-hold dive. The reduction inpressure associated with returning to the surface causes theoxygen partial pressure to fall faster than through metabolismof the gas alone. See also Hyperventilation, Hypoxia, andHypoxic Loss of Consciousness.SnorkelingSwimming with mask, snorkel and fins. Snorkelers mayremain at the surface or conduct breath-hold dives. See alsoBreath-Hold Diving and Freediving.Square DiveA dive in which the descent is made to a given depth andwhere the diver remains for the entire dive before ascendingto the surface.Surface Oxygen Treatment (SOT)Oxygen delivered at the surface with a therapeutic intent. Gasmay flow from the supply system in a continuous mode orthrough a demand valve upon inspiration of the conscious,spontaneously breathing injured person. The breathing circuitmay be open (dumping exhaled gas) or closed (reusingexhaled gas after it is scrubbed of carbon dioxide). The deliveryinterface may be some form of simple non-breathing facemask,a partial rebreathing facemask or a nasal cannula. Thefraction of oxygen delivered to the injured person and theoxygen flow rate required will vary dramatically dependingon system configuration and use.Trimix – See Mixed GasType I DCS (DCS I, Musculoskeletal DCS)Decompression sickness where the symptoms are felt to benon-neurological in origin such as itching, rash, joint or musclepain.Type II DCS (DCS II, Neurological or Cardiopulmonary DCS)Decompression sickness where there is any symptom referableto the nervous or cardiovascular system.Type III DCS (DCS III)A more serious type of DCS that is sometimes seen after longdeep dives with a rapid ascent. Type III DCS is thought to becaused by the occurrence of arterial gas embolization after adive where a large quantity of inert gas has been absorbed bythe tissues. Presumably the arterial bubbles continue to takeup inert gas and grow, causing a deteriorating clinical picturethat becomes rapidly worse.Underlying Cause of DeathThe problem(s) creating a situation resulting in death by anobvious means, for instance, drowning.URI (Upper Respiratory Infection)The most frequently reported acute health problem from theDAN sample of injured divers.Subcutaneous Air (Subcutaneous Emphysema)Air under the skin after pulmonary barotrauma. The most frequentlocation is around the neck and above the collarboneswhere the gas may migrate after pulmonary overexpansion.DAN’s <strong>Report</strong> on Decompression Illness, Diving Fatalities and Project Dive Exploration: 2004 Edition 135