Long-term changes in spirometry in occupational divers: a 10-25 year audit.

AIM: To determine whether long-term engagement in occupational diving causes significant changes in spirometric measurements. METHOD: All divers with adequate spirometric records spanning at least 10 years were identified from the New Zealand occupational diver database. Changes in lung function over time were compared with normative values derived using published prediction equations. Any significant changes were tested for correlation with age, duration of occupational diving, gender, smoking history and body mass index (BMI). RESULTS: Spirometry data spanning periods of 10 to 25 years were analysed for 232 divers. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) declined with increasing duration of diving, but slightly less than predicted with increasing age, while peak expiratory flow (PEF) declined more than expected for age in longer-term divers. The changes in PEF were statistically significant, and correlated with duration of diving exposure, initial age and final BMI. Nevertheless, the changes were small and probably clinically insignificant. CONCLUSION: We compared changes in spirometric parameters over long periods of occupational diving with normative data and found no clinically significant differences that could be attributed to diving. We found no justification for routine spirometry in asymptomatic divers.

Comparison of Australian and New Zealand referral rates for hyperbaric oxygen in oro-facial osteoradionecrosis: evidence-based, funding constraint or clinician whim?

AIM: To compare Australian and New Zealand (NZ) rates of referral to hyperbaric units for patients with, or at risk of developing mandibular or maxillary osteoradionecrosis (ORN) due to a history of radiotherapy for oro-pharyngeal cancer. METHOD: Relevant patient treatment data from all hyperbaric units in Australia and NZ were collated and analysed. RESULTS: The rate of referral to hyperbaric units in Australia for treatment or prophylaxis of patients with, or at risk of oro-facial ORN, was 1.7 times the rate of referral in NZ. Within Australia, there was a greater than three-fold interstate variation. CONCLUSION: There is a significant referral rate difference both within Australia and between Australia and NZ for hyperbaric oxygen therapy for oro-facial ORN. Possible reasons for this difference include access to funding, logistical difficulties, clinician preference for an alternative treatment and clinician attitudes to hyperbaric oxygen.

Decompression illness in divers treated in Auckland, New Zealand, 1996-2012.

INTRODUCTION: The treatment of divers for decompression illness (DCI) in Auckland, New Zealand, has not been described since 1996, and subsequent trends in patient numbers and demographics are unmeasured. METHODS: This was a retrospective audit of DCI cases requiring recompression in Auckland between 01 January 1996 and 31 December 2012. Data describing patient demographics, dive characteristics, presentation of DCI and outcomes were extracted from case notes and facility databases. Trends in annual case numbers were evaluated using Spearman's correlation coefficients (ρ) and compared with trends in entry-level diver certifications. Trends in patient demographics and delay between diving and recompression were evaluated using regression analyses. RESULTS: There were 520 DCI cases. Annual caseload decreased over the study period (ρ = 0.813, P < 0.0001) as did entry level diving certifications in New Zealand (ρ = 0.962, P < 0.0001). Mean diver age was 33.6 (95% confidence limits (CI) 32.7 to 34.5) years and age increased (P < 0.0001) over the study period. Median (range) delay to recompression was 2.06 (95% CI 0.02 to 23.6) days, and delay declined over the study period (P = 0.005). CONCLUSIONS: Numbers of DCI cases recompressed in Auckland have declined significantly over the last 17 years. The most plausible explanation is declining diving activity but improvements in diving safety cannot be excluded. The delay between diving and recompression has reduced.

A systematic review of factitious decompression sickness.

We present a case of factitious decompression sickness (DCS) involving a patient emergently treated at a hyperbaric medicine facility in New Zealand. Patients with factitious disorder feign illnesses such as DCS in order to receive care and attention despite the lack of an underlying illness. Other studies have suggested that 0.6% to as many as 9.3% of hospital admissions are factitious in nature. Therefore we believe that factitious DCS is occurring more often than hyperbaric clinicians suspect. DCS can be life-threatening, and hyperbaric medicine clinicians will almost always "err on the side of caution" when patients are referred with symptoms of DCS. Because DCS can be diagnosed based on subjective symptoms and self-reported history, there are opportunities for factitious patients to receive hyperbaric therapy. The costs associated with factitious DCS include transport, staff resources and preventing patients with treatable conditions from accessing the hyperbaric chamber. We performed a systematic review of the literature and found eight additional reported cases of confirmed or suspected factitious DCS. We report our findings and recommendations for hyperbaric medicine specialists regarding the recognition and management of factitious DCS.

Severe cyclophosphamide-induced haemorrhagic cystitis treated with hyperbaric oxygen.

AIM: Cyclophosphamide-induced haemorrhagic cystitis (CHC) is an uncommon but well-recognised condition caused by a metabolite, acrolein, which is toxic to the urothelium. Based on similarities in the histopathology of radiation- and chemotherapy-induced haemorrhagic cystitis, benefit from hyperbaric oxygen therapy (HBOT) has been proposed. HBOT produces an increased oxygen partial pressure diffusion gradient between the circulation and surrounding tissues, which enhances neutrophil function and fibroblast and macrophage migration into damaged hypoxic soft tissue, promoting collagen formation, fibroblast growth, angiogenesis and white-cell bacterial killing. There are only isolated case reports of HBOT for CHC, in the literature so we reviewed the New Zealand experience with HBOT in CHC. METHOD: The case records of all patients with CHC referred to the three hyperbaric medicine units in New Zealand between 2000 and 2007 were reviewed retrospectively. RESULTS: Six patients, with life-threatening haemorrhage at the time of referral for HBOT weeks or months after initial presentation with CHC, were identified. Cessation of bleeding occurred in all six patients after 14 to 40 HBOT, without complications. All patients remained clear of haematuria at 11 to 36 months follow-up. CONCLUSIONS: We recommend the use of HBOT in the management of intractable cyclophosphamide-induced haemorrhagic cystitis as an effective and low-risk therapy.