Decompression sickness after a highly conservative dive in a diver with known persistent foramen ovale: Case report.

A diver returned to diving, 15 months after an episode of neuro-spinal decompression sickness (DCS) with relapse, after which she had been found to have a moderate to large provoked shunt across a persistent (patent) foramen ovale (PFO), which was not closed. She performed a single highly conservative dive in line with the recommendations contained in the 2015 position statement on PFO and diving published jointly by the South Pacific Underwater Medicine Society and the United Kingdom Sports Diving Medical Committee. An accidental Valsalva manoeuvre shortly after surfacing may have provoked initial symptoms which later progressed to DCS. Her symptoms and signs were milder but closely mirrored her previous episode of DCS and she required multiple hyperbaric oxygen treatments over several days, with residua on discharge. Although guidance in the joint statement was mostly followed, the outcome from this case indicates that there may be a subgroup of divers with an unclosed PFO, who have had a previous episode of serious DCS, who may not be safe to dive, even within conservative limits.

A technical diving-related burns case: treatment in a remote location.

Injuries suffered as a result of a rebreather oxygen explosion and fire occurred to a diver on vacation in the island state of Chuuk, Micronesia. The medical and logistical management of the diver in a remote location are described. The mechanism of both the fire and the subsequent blast and burn injuries are discussed. Prevention of and preparation for such incidents are discussed in the context of the increasing frequency of dive and adventure travel to remote areas.

Cerebral arterial gas embolism in a professional diver with a persistent foramen ovale.

A 33-year-old, male professional scallop diver diving on the Outer Hebrides in Scotland rapidly developed symptoms of cerebral arterial gas embolism following a provocative dive with possibly a fast ascent. During transfer by helicopter to the mainland for treatment, his symptoms improved on surface oxygen. He was recompressed on a Royal Navy Treatment Table 62 (RN TT62) with complete resolution. Just over six weeks later, again diving on the Outer Hebrides and after adopting more conservative diving practices, he developed symptoms and signs of vestibular decompression sickness after a problem-free dive, with dizziness, poor co-ordination and gait, nausea and vomiting, and rotational vertigo. He was again transported to the mainland for recompression treatment. He received an extended RN TT62 and required five further Comex 12 (223 kPa) hyperbaric oxygen treatments over the following three days before he was symptom free. A 4 mm persistent foramen ovale (PFO) was subsequently diagnosed and he underwent successful closure of the defect with Amplatzer device and returned to commercial diving a year later.

Emergency recompression: clinical audit of service delivery at a national level.

Clinical audit is an essential element to the maintenance or improvement of delivery of any medical service. During the development phase of a National Recompression Registration Service for Scotland, clinical audit was initiated to provide a standardised tool to monitor the quality of outcome with respect to the severity of presentation. A functional audit process was an essential consideration for planned future measurement of treatment efficacy at local (single hyperbaric unit) and national (multiple hyperbaric units) scales. The audit process was designed to be undemanding, robust and informative, irrespective of the experience of treatment centre and of the clinician in charge of treatment. The clinical records from 104 cases of divers with decompression illness were used to derive and evaluate measures of severity and clinical outcome that could be used for audit and quality assurance. The various measures of disease severity were examined against clinical outcome and days spent in care after admission to a hyperbaric unit. An initial version of the clinical audit format that was developed from this process is presented.

Analyses of treatment for divers with actual or suspected decompression illness.

INTRODUCTION: We examined national and single-centre datasets in Scotland to determine any trends in the treatment of diving-related disease and to assess how the choice of first treatment may be linked to the divers' condition on referral and on discharge. METHOD: Two datasets were analysed: (1) 300 divers treated for actual or suspected decompression illness by the Dunstaffnage Hyperbaric Unit (Oban) between 1972 and 2007; and (2) 536 divers treated by the Scottish recompression chamber network between 1991 and 2003 (some data were common to both sets). The type and frequency of initial and any subsequent hyperbaric treatment used were examined. Any trends in demographics, reasons for diving, dive series profiles and condition on admission were examined. RESULTS: Ninety to 92 per cent of treated divers received standard or modified Royal Navy treatment table 62 (RN 62) or US Navy table 6 (USN 6) for their primary treatment. Nearly a third of the divers (32%) were rated as having a severe condition on admission; only 4% had a severe condition on discharge. Analysis of outcome versus treatment type was complicated by divers with more severe symptoms on referral tending to have a worse outcome (concomitant with their referral condition) while receiving more prolonged and complex treatments. CONCLUSIONS: Shorter and shallower treatment tables (e.g., US Navy table 5, Royal Navy table 61), when used as first treatment, may result in poorer outcomes compared with RN 62/USN 6 treatment. Although subject to ongoing analysis, the shorter and/or shallower treatments have been discouraged as a first treatment in Scotland.

Saturation treatment in shore-based chambers for divers with deteriorating cerebro-spinal decompression sickness.

Nearly 4% of all primary recompression treatments in Scotland employ saturation tables (helium/oxygen-oxygen/air or oxygen/air alone). These cases usually involve divers presenting at the surface who then develop deteriorating spinal cord injury with varying degrees of cerebral involvement. Treatment is delivered either through immediate saturation therapy or through conversion of failing or failed primary treatment. The basic principles and delivery protocols of saturation treatment are outlined. A case study from both types of treatment is presented to illustrate the forms of decompression sickness that may require saturation treatment and how the treatments are initiated and evolve.

The consequences of misinterpreting dive computers: three case studies.

Three cases are presented where there is a direct link between how the divers used their dive computers and the eventual requirement for their therapeutic recompression. The first case involves a diver with a previous history of decompression incidents making adjustments to their dive computer without understanding the outcomes of those alterations. The second case involves two divers running out of air and surfacing having missed significant amounts of decompression, caused by the dive computer not reducing their decompression obligation in actual time. This effect and performance differences between three models of computers were demonstrated in subsequent compression chamber trials reported here. The final case involves a diver who completed their dive within the indicated limits of their dive computer but subsequently developed serious neurological decompression sickness that left severe permanent residua. Compression chamber trials suggested that a combination of poor measurement accuracy and outdated decompression management in the computer used could have contributed to the diver's eventual poor outcome.

Two case reports of epileptic seizures related to probable cerebral arterial gas embolism.

Two cases are presented of divers suffering epileptic seizure and loss of consciousness as a result of probable cerebral arterial gas embolism (CAGE). Both cases had apparently problem-free dives with no obvious provocation for CAGE, though one case may have been having repeated embolisms for some time in their diving career. Demonstrated also is the Type III form of decompression sickness, where spinal cord disease follows CAGE in a biphasic manner.

Comparative incidences of decompression illness in repetitive, staged, mixed-gas decompression diving: is 'dive fitness' an influencing factor?

Wreck diving at Bikini Atoll consists of a relatively standard series of decompression dives with maximum depths in the region of 45-55 metres' sea water (msw). In a typical week of diving at Bikini, divers can perform up to 12 decompression dives to these depths over seven days; on five of those days, divers can perform two decompression dives per day. All the dives employ multi-level, staged decompression schedules using air and surface-supplied nitrox containing 80% oxygen. Bikini is serviced by a single diving operator and so a relatively precise record exists both of the actual number of dives undertaken and of the decompression illness incidents both for customer divers and the dive guides. The dive guides follow exactly the dive profiles and decompression schedules of the customers. Each dive guide will perform nearly 400 decompression dives a year, with maximum depths mostly around 50 msw, compared with an average of 10 (maximum of 12) undertaken typically by each customer diver in a week. The incidence of decompression illness for the customer population (presumed in the absence of medical records) is over ten times higher than that for the dive guides. The physiological reasons for such a marked difference are discussed in terms of customer demographics and dive-guide acclimatization to repetitive decompression stress. The rates of decompression illness for a range of diving populations are reviewed.