Diving and hyperbaric medicine最新文献

Introduction: Measurements of forced vital capacity (FVC) have shown that divers have larger lungs than members of the general population. Bullae or decompression illness (DCI) secondary to pulmonary barotrauma is more likely to occur in large lungs (LLs) than in normal lungs (NLs). This study retrospectively compared lung function, high-resolution CT (HRCT) scan anomalies, the unfit-to-dive rate, and the prevalence of DCI in groups of divers with LLs and NLs.

Methods: The results of fitness examinations of divers with LLs (FVC z-score > 1.96) and NLs (FVC z-score ≤ 1.96) from 2011 to 2020 were retrospectively evaluated. Data were obtained from lung function tests, HRCT results, fitness examination outcomes, and whether the diver did or did not have DCI.

Results: The study included 1,069 divers, with 65 subjects, all male, fulfilling the requirements for LLs. Subjects with LLs had a significantly higher z-scores for FVC and FEV1 but a significantly lower FEV1/FVC ratio, than subjects with NLs. The rates of bullae, DCI, and unfit-to-dive did not differ significantly in the two groups.

Conclusions: Although FEV1/FVC ratio was significantly lower in the LL than in the NL group, there were no between-group differences in the rates of bullae and DCI. These findings suggest that subjects with LLs are not at a higher risk of bullae and DCI than are subjects with NLs.

Treatment of suspected upper lip area vascular occlusion caused by facial hyaluronic acid filler injections with hyperbaric oxygen is reported. The patient was initially treated with hyaluronidase injections in the cosmetic clinic then again in the emergency department. Persistent symptoms and signs of occlusion prompted hyperbaric oxygen treatment at 284 kPa (nine treatments over seven days). The outcome was positive for this patient and adds supportive evidence to the sparse literature, which are mainly case studies.

Introduction: Doppler ultrasound is used to detect inert gas bubbles in the body following decompression from dives. Two sites may be monitored, the precordial (PC) and subclavian (SC) positions. PC is the predominant site, allowing observation of bubbles returning from the entire body. However, the SC site provides unambiguous signals, whereas the PC site is noisy and difficult to grade. This retrospective study compared agreement of PC and SC Doppler data.

Methods: Datasets from the large University of California at San Diego Doppler database were graded on the Kisman Masurel (KM) scale and included: one PC measurement at rest followed by three during movement (n = 4 measurements); this was repeated for the left (n = 4 measurements) and right (n = 4 measurements) SC veins, producing a set of 12 grades. Primary analysis included: agreement between resting PC and SC grades, between movement PC and SC grades, and for unmatched grades, whether the SC grade was higher or lower than PC.

Results: Four-hundred and fifty-three datasets were available (5,436 individual recordings). At rest, 281 (62.0%) PC and SC grades matched (weighted kappa agreement 0.33, 95% CI ± 0.04), while only 176 (38.9%) movement grades matched (0.29, ± 0.02). Of the unmatched data, resting SC grades were higher than PC in 70.3% and lower in 29.6%; after movement, SC grades were higher in 45.8% and lower in 54.2%.

Conclusions: These data revealed a large discrepancy between PC and SC grades. Overall, this suggests that Doppler observations from both positions will give the most comprehensive representation of bubble load.

This consensus statement is the product of a workshop at the South Pacific Underwater Medicine Society Annual Scientific Meeting 2024 with representation of the United Kingdom Diving Medical Committee (UKDMC) present, and subsequent discussions included the entire UKDMC. A large right-to-left shunt across a persistent (patent) foramen ovale (PFO), an atrial septal defect (ASD) or a pulmonary shunt is a risk factor for some types of decompression sickness (DCS). It is agreed that routine screening for a right-to-left shunt is not currently justifiable, but certain high risk sub-groups can be identified. Individuals with a history of cerebral, spinal, vestibulocochlear, cardiovascular or cutaneous DCS, migraine with aura or cryptogenic stroke; a family history of PFO or ASD and individuals with other forms of congenital heart disease have a higher prevalence, and for those individuals screening should be considered. If screening is undertaken, it should be by bubble contrast transthoracic echocardiography with provocative manoeuvres (including Valsalva release and sniffing). Appropriate quality control is important. If a shunt is present, advice should be provided by an experienced diving physician taking into account the clinical context and the size of shunt. If shunt-mediated DCS is diagnosed, the safest option is to stop diving. Another is to perform dives with restrictions to reduce the inert gas load, which is facilitated by limiting depth and duration of dives, breathing a gas with a lower percentage of nitrogen and reducing repetitive diving. Divers may consider transcatheter device closure of the PFO or ASD in order to return to normal diving. If transcatheter PFO or ASD closure is undertaken, repeat bubble contrast echocardiography must be performed to confirm adequate reduction or abolition of the right-to-left shunt, and the diver should have stopped taking potent anti-platelet therapy (low dose aspirin is acceptable) before resuming diving.

Introduction: Venous gas emboli (VGE) are a common surrogate experimental endpoint for decompression sickness (DCS). VGE numbers are graded, and the peak post-dive grade is associated with the probability of DCS (PDCS). VGE are typically graded with the subject at rest when bubble numbers are stable, and again after limb flexions which elicit a transient shower of bubbles. Detection of VGE using two-dimensional (2-D) echocardiography has become common, but the principal grading scales do not specify how to grade VGE after limb movement.

Methods: This was a retrospective analysis of 1,196 man-dives following which VGE were detected using 2-D echocardiography and graded on a scale 0-4 and 41 cases of DCS occurred. PDCS was estimated for each peak post-dive VGE grade from the cumulative incidence of DCS. Two different definitions of movement VGE grades were assessed in 84 measurements; the grade was either the maximum VGE number sustained for one diastole (1-cycle) or for six cardiac cycles (6-cycle).

Results: For each peak post-dive VGE grade (maximum of rest or movement) the cumulative incidences of DCS (%) were: grade 0 (0%); grade 1 (1.3%); grade 2 (2.5%); grade 3 (4.6%); grade 4 (5.7%). When grading movement VGE, 57% of 1-cycle grade 4 were reduced to grade 3 using the 6-cycle definition.

Conclusions: There is a need for consensus in the research community on how to assign movement VGE grades when using 2-D echocardiography. Publications should carefully explain methodology for assigning VGE grades and consider differences in methodologies when comparing historical data sets.

Introduction: We hypothesised that although thicker (≥ 7 mm) wetsuits delay hypothermia and allow divers to dive in cooler waters, they may hinder pulmonary function. The aim of this study was to investigate whether thicker wetsuits worn by Tasmanian divers affected lung volumes, primarily the forced vital capacity (FVC) and forced expiratory volume, one second (FEV1).

Methods: Sixty-two volunteer active divers were recruited from recreational dive clubs and Tasmania's occupational diving industry. After confirming fitness and that the divers were currently active, spirometry testing was performed with and without the divers' usual wet suits, in a controlled dry environment. Suits were of varying thickness, but all were ≥ 7 mm thickness.

Results: All divers had significantly reduced lung volumes when wearing ≥ 7 mm wetsuits. Recreational divers had greater decrements (-7% FVC and -5% FEV1), compared to occupational divers (-3% FVC, -3% FEV1). Males' lung volumes declined -4% FVC and -4 % FEV1, whereas females declined -7 % FVC and -6 % FEV1. Female recreational divers experienced the greatest negative impact from thicker wetsuits (up to 15% reduction in FVC), and this group also demonstrated an inverse relationship between increasing wetsuit thickness and declining lung volumes.

Conclusions: Wearing thicker wet suits aids in thermal protection in temperate water diving but this study suggests it has negative effects on lung volumes. The real-life impact of this negative effect may be minor in fit healthy divers but might add additional risk to a less fit, recreational diving population with medical comorbidities.

Introduction: Current treatment of idiopathic sudden sensorineural hearing loss (ISSNHL) includes a combination of corticosteroids and hyperbaric oxygen therapy (HBOT) without established dose. The objective of this study was to investigate whether > 10 HBOT treatments offers improved outcome over 10 treatments.

Methods: A retrospective chart review was performed of patients treated with HBOT for ISSNHL between 2013 and 2022 at the Royal Brisbane and Women's Hospital. Pure tone average results from 500, 1,000, 2,000, 4,000 hertz (PTA4) were obtained pre-treatment, after treatment 10, and six weeks post-treatment.

Results: There were 479 patients treated for ISSNHL: 144 having audiograms six weeks post-treatment, 140 of whom also had an audiogram after treatment 10. At six weeks post treatment 22% (32/144) had normal hearing (PTA4 < 25 dB), and 69% (99/144) had a PTA4 gain ≥ 10 dB. At the treatment 10 audiogram, 83/140 (59%) were improved. From these, 5/21 (24%) with 10 treatments and 14/57 (25%) with > 10 treatments had a further PTA4 gain of ≥ 10 dB occurring after treatment 10. For those 57/140 (41%) not improved at treatment 10, 7/26 (27%) with 10 treatments and 12/31 (39%) with > 10 treatments were improved at six weeks post-treatment with 5/7 (71%) and 8/12 (67%) of the 10 and > 10 groups respectively having ≥ 10 dB gain in PTA4 occurring after treatment 10. Overall, there was no significant difference in mean (SD) hearing gain from treatment 10 to six weeks post treatment between the 10 treatments and > 10 treatments groups: 4.73 (8.90) versus 5.93 (11.25) dB, P = 0.53.

Conclusions: In conjunction with steroids, 10 treatments of hyperbaric oxygen therapy appear to offer equivalent benefit to > 10 treatments. Similar improvements in PTA4 and hearing recovery occur after 10 HBOT treatments independent of ongoing HBOT. A prospective trial comparing 10 versus > 10 treatments for ISSNHL with outcome measured beyond treatment completion is warranted.

Introduction: This report describes the outcomes of sensorineural hearing loss (SNHL) due to cochlear inner ear barotrauma (IEBt) in five divers treated with hyperbaric oxygen (HBOT).

Methods: The case histories of five consecutive divers presenting with SNHL from IEBt due to diving, were reviewed. All divers provided written consent for their data to be included in the study. All had reference pre-injury audiograms. All noted ear problems during or post-dive. Independent audiologists confirmed SNHL in all divers prior to HBOT, then assessed outcomes after HBOT.

Results: Three divers breathed compressed air on low risk dives, and two were breath-hold. None had symptoms or signs other than hearing loss, and none had vestibular symptoms. All could equalise their middle ears. Inner ear decompression sickness was considered unlikely for all cases. All were treated with HBOT 24 hours to 12 days after diving. Two divers received no steroid treatment, one was treated with HBOT after an unsuccessful 10-day course of steroids, and two divers received steroids two days after commencing HBOT. All divers responded positively to HBOT with substantial improvements in hearing across multiple frequencies and PTA4 measurements. Median improvement across all frequencies (for all divers) was 28 dB, and for PTA4 it was 38 dB.

Conclusions: This is the first case series describing use of HBOT for IEBt-induced SNHL. The variable treatment latency and use/timing of steroids affects data quality, but also reflects pragmatic reality, where steroids have minimal evidence of benefit for IEBt. HBOT may benefit diving related SNHL from IEBt with no evidence of perilymph fistula, and provided the divers can clear their ears effectively. A plausible mechanism is via correction of ischaemia within the cochlear apparatus. More study is required including data collection via national or international datasets, due to the rarity of IEBt.

Introduction: Hyperbaric oxygen treatment (HBOT) is considered definitive treatment for decompression illness. Delay to HBOT may be due to dive site remoteness and limited facility availability. Review of cases may help identify factors contributing to clinical outcomes.

Methods: Injured divers treated in Townsville from November 2003 through December 2018 were identified. Information on demographics, initial disease severity, time to symptom onset post-dive, time to pre-HBOT oxygen therapy (in-water recompression or normobaric), time to HBOT, and clinical outcome was reviewed. Data were reported as median (interquartile range [IQR]) with Kruskal-Wallis and chi-square tests used to evaluate group differences. Significance was accepted at P < 0.05.

Results: A total of 306 divers (184 males, 122 females) were included with a median age of 29 (IQR 24, 35) years. Most divers had mild initial disease severity (n = 216, 70%). Time to symptom onset was 60 (10, 360) min, time to pre-HBOT oxygen therapy was 4:00 (00:30, 24:27) h:min, and time to start of HBOT was 38:51 (22:11, 69:15) h:min. Most divers (93%) had a good (no residual or minor residual symptoms) outcome and no treated diver died. Higher initial disease severity was significantly associated with shorter times to symptom onset, oxygen therapy, and HBOT, and with worse outcomes. The paucity of cases receiving HBOT with minimal delay precluded meaningful evaluation of the effect of delay to HBOT.

Conclusions: Most divers had mild initial disease severity and a good outcome. Higher initial disease severity accelerated the speed of care obtained and was the only factor associated with poorer outcome.

Introduction: The aim was to determine the cost-effectiveness and cost-utility of additional hyperbaric oxygen therapy (HBOT) compared to standard care (SC) for ischaemic diabetic foot ulcers (DFUs) regarding limb salvage and health status.

Methods: An economic analysis was conducted, comprising cost-effectiveness and cost-utility analyses, with a 12-month time horizon, using data from the DAMO₂CLES multicentre randomised clinical trial. Cost-effectiveness was defined as cost per limb saved and cost-utility as cost per quality-adjusted life year (QALY). The difference in cost effectiveness between HBOT+SC and SC alone was determined via an incremental cost-effectiveness ratio (ICER).

Results: One-hundred and twenty patients were included, with 60 allocated to HBOT+SC and 60 to SC. No significant cost difference was found in the intention-to-treat analysis: €3,791 (bias corrected and accelerated [BCA] 95% CI, €3,556 - €-11,138). Cost per limb saved showed an ICER of €37,912 (BCA 95% CI €-112,188 - €1,063,561) for HBOT+SC vs. SC. There was no significant difference in mean QALYs: 0.54 for HBOT+SC vs. 0.56 for SC alone (-0.02; BCA 95% CI -0.11-0.08). This resulted in a cost-utility of minus €227,035 (BCA 95% CI €-361,569,550 - €-52,588) per QALY. Subgroup analysis for Wagner stages III/IV showed an ICER of €19,005 (BCA 95%CI, -€18,487 - €264,334) while HBOT did not show any benefit for Wagner stage II.

Conclusions: HBOT as an adjunct to SC showed no significant differences in costs and effectiveness for patients with DFUs regarding limb salvage and health status. However, for patients with Wagner stage III/IV ischaemic DFUs there was a trend towards better effectiveness and cost-effectiveness.