Equipoise: an important ethical consideration when contemplating participation in a randomised controlled trial of hyperbaric oxygen treatment in necrotising soft tissue infections.

A proposal for a large, multi-centre, randomised controlled trial investigating the role of hyperbaric oxygen treatment (HBOT) in necrotising soft tissue infections (NSTI) has led to much discussion locally and internationally about whether participation is ethical for a centre where stakeholders already consider HBOT standard practice. This article systematically addresses the concept of clinical equipoise specific to the role of HBOT in NSTI, and presents a series of considerations to be taken into account by key stakeholders at potential participating sites.

Performance of the BBraun perfusor space syringe driver under hyperbaric conditions.

BACKGROUND: The BBraun Perfusor Space™ syringe driver is already in use by ambulance services and retrieval teams but has not previously been assessed for hyperbaric chamber use. METHODS: Pump flow accuracy was tested at rates between 1 and 40 ml· h⁻¹ using three different brands of 50 ml syringe. Function of the occlusion alarms was assessed using the same syringes. The hyperbaric profile involved pressurisation to 284 kPa at 30 kPa· min⁻¹, 30 min at 284 kPa and decompression at 30 kPa· min⁻¹. Output was recorded from differences in weight of collection containers. A single device was tested. RESULTS: Performance was highly dependent on the syringe type used, with two of the three 50 ml syringes used demonstrating 'stiction' at both low and high occlusion pressure alarm settings, most marked during pressurisation. On decompression from 284 kPa all syringes alarmed at significantly lower pressures. Because of the stiction problems only the flow measurements for the BBrown Omni¬ x 50 ml syringes are reported. At a pressure of 284 kPa, the difference between programmed and delivered rates was within the manufacturer's specification of 10%: at 40 ml· h⁻¹ (median variation 1.25%, IQR 0.5-1.7%), 10 ml· h⁻¹ (8.6%, IQR 8-9.2%), 5 ml· h⁻¹ (-8.8%, IQR - 1.6-8.8%) and 1 ml· h⁻¹ (-4%, IQR 4-12%). Pressurisation was associated with significantly lower flow rates whilst decompression was associated with significantly increased rates. Limited testing at 405 kPa was also within the manufacturer's specifications. CONCLUSION: A BBraun Infusor Space syringe driver performed within acceptable performance criteria but is highly dependent on syringe type and flow rates. The potential for the device to under deliver on pressurisation and over deliver on depressurisation, however, suggests vigilance and appropriate rate adjustments may be necessary during these phases.

A 10-year estimate of the incidence of decompression illness in a discrete group of recreational cave divers in Australia.

INTRODUCTION: The vast majority of freshwater cave diving in Australia occurs within the limestone caves of the Gambier karst in the south-east of South Australia. The incidence of decompression illness (DCI) in cave divers is presumed to be higher than open-water recreational divers because of the greater depths involved, but has not previously been reported. Our aim was to determine the incidence of DCI in cave divers, the patterns of diving and the outcome of hyperbaric treatment. METHODS: This was a retrospective cohort study of cave divers with DCI presenting to the Royal Adelaide Hospital or The Alfred Hospital over a 10-year period between 2002 and 2012. We reviewed case notes of cave divers who were treated for DCI after diving in the Mt Gambier karst. As there are no records of the number of dives performed during the study period we generated a denominator for the incidence of DCI by extrapolating available data and making a number of assumptions about the number of dives per dive permit issued. RESULTS: Sixteen patients were treated for DCI during the study period. The precipitating dive was a single deep decompression dive in seven cases, multiday repetitive dive sequences in eight and a non-decompression dive in one. Three of the 16 cases of DCI involved dives in excess of 90 metres' fresh water (mfw) using trimix. As the total estimated number of dives in the study period was approximately 57,000 the incidence of DCI in Australian cave divers was estimated to be 2.8:10,000 (0.028%). It is possible that the overall incidence of DCI is as high as 0.05%, and even higher when dives to depths greater than 90 mfw are involved. CONCLUSIONS: The estimated incidence of DCS in this series is lower than expected but consistent with other series describing DCI in cold-water recreational diving.

Hyperbaric oxygen in the treatment of calciphylaxis: A case series and literature review.

AIMS: Calcific uraemic arteriolopathy (CUA) or calciphylaxis is most commonly seen in end-stage renal disease and is associated with significant morbidity and mortality. The aim of this study was to determine whether hyperbaric oxygen therapy (HBOT) is effective in healing calciphylaxis lesions and to determine if there are any patient factors that can predict wound healing and patient survival. METHODS: We identified by retrospective review all cases of CUA referred to our institution for treatment with HBOT. We documented the clinical and biochemical parameters of this patient population, the size and distribution of the lesions as well as wound outcomes and patient survival following treatment. RESULTS: A total 46 patients were identified with CUA associated with renal failure. Of the 46 patients, only 34 received a full course of HBOT. The balance was deemed unsuitable for treatment or was unable to tolerate treatment and was palliated. Of the 34 patients that received a full course of HBOT, 58% showed improvement in their wound scores, with more than half of these patients having complete healing of their wounds. The balance did not benefit from the therapy and had a very poor prognosis. Those that benefited from HBOT survived on average for more than 3 years. The only factor significantly associated with improved wound healing and survival was diabetes. CONCLUSION: This retrospective analysis suggests a role for HBOT in the treatment of CUA with more than half of the treated patients benefiting and surviving for an average of more than 3 years.