Acute Effects on the Human Peripheral Blood Transcriptome of Decompression Sickness Secondary to Scuba Diving.

Decompression sickness (DCS) develops due to inert gas bubble formation in bodily tissues and in the circulation, leading to a wide range of potentially serious clinical manifestations. Its pathophysiology remains incompletely understood. In this study, we aim to explore changes in the human leukocyte transcriptome in divers with DCS compared to closely matched unaffected controls after uneventful diving. Cases (n = 7) were divers developing the typical cutis marmorata rash after diving with a confirmed clinical diagnosis of DCS. Controls (n = 6) were healthy divers who surfaced from a ≥25 msw dive without decompression violation or evidence of DCS. Blood was sampled at two separate time points-within 8 h of dive completion and 40-44 h later. Transcriptome analysis by RNA-Sequencing followed by bioinformatic analysis was carried out to identify differentially expressed genes and relate their function to biological pathways. In DCS cases, we identified enrichment of transcripts involved in acute inflammation, activation of innate immunity and free radical scavenging pathways, with specific upregulation of transcripts related to neutrophil function and degranulation. DCS-induced transcriptomic events were reversed at the second time point following exposure to hyperbaric oxygen. The observed changes are consistent with findings from animal models of DCS and highlight a continuum between the responses elicited by uneventful diving and diving complicated by DCS. This study sheds light on the inflammatory pathophysiology of DCS and the associated immune response. Such data may potentially be valuable in the search for novel treatments targeting this disease.

Hyperbaric oxygen therapy awareness within a doctor population.

Hyperbaric medicine is a relatively young specialty that remains in the blind spot of most doctors' awareness. This study endeavors to identify the level of awareness of the indications for hyperbaric oxygen (HBO2) therapy among a doctor population in a developed country and factors which may improve referral rates. An anonymized questionnaire was distributed to doctors licensed to practice in Malta. Questions included physician specialty, demographics and previous exposure to diving and/or hyperbaric medicine. Moreover, two scoring systems were used to score subjects on HBO2-related topics. Binomial logistic regression models and generalized linear models were used in the statistical analysis. A total of 152 full replies were obtained and analyzed. Respondents who had visited a hyperbaric unit (HBU) (p=0.002) or attended a lecture on HBO2 (p=0.006) scored better than their counterparts, indicating better awareness of HBO2 indications and local chamber location. A previous HBU visit (p=0.001), being a hospital-based doctor (p=0.027) and a history of scuba diving (p=0.03) were associated with willingness to refer patients for HBO2 in the future. Encouraging visits to an HBU has been shown to be associated with multiple factors, which are expected to result in improved referral rates. Targeted educational sessions to doctors and medical students are likely to be beneficial in improving correct referral of patients for HBO2. The findings from this study may prove useful in improving appropriate referral rates of patients who may benefit from this useful treatment modality.

Increasing prevalence of vestibulo-cochlear decompression illness in Malta - an analysis of hyperbaric treatment data from 1987-2017.

INTRODUCTION: Scuba diving is a big part of the tourism sector in Malta, and all the cases of decompression illness (DCI)are treated within the single hyperbaric referral centre in the country. METHODS: This retrospective analysis reviews all the medical records of divers with DCI in Malta within the 30-year period between 1987 to 2017 who required recompression therapy with hyperbaric oxygen. RESULTS: There were 437 discrete cases of DCI managed with recompression therapy. Amongst DCI subtypes, the prevalence of musculo-skeletal DCI is decreasing, whereas that of vestibulo-cochlear DCI is increasing. CONCLUSION: The increasing prevalence of vestibulo-cochlear DCI may be due to a change in diving practices in Malta.

Anton's syndrome as a presentation of decompression illness.

We present a case of a patient with Anton's syndrome due to decompression illness (DCI) after recreational scuba diving. Visual anosognosia, or denial of loss of vision, which is associated with lack of awareness regarding visual loss in the setting of cortical blindness, is known as Anton's syndrome (also termed Anton-Babinski syndrome). Our patient presented with progressive neurological DCI treated with repeated recompression. The anosogosia resolved after 48 h. Subsequent echocardiography revealed a persistent (patent) foramen ovale.