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A 41-year-old female nurse had cutaneous decompression sickness on two occasions after acting as an inside chamber attendant for patients receiving hyperbaric oxygen. She breathed air during the treatments at pressures equivalent to 14 and 18 metres of seawater, but each time she decompressed whilst breathing oxygen. Latency was 2.5 hours and one hour. She was found to have an 11 mm diameter persistent foramen ovale. It was closed and she returned to work without recurrence of decompression sickness. Review of the literature suggests that shunt mediated decompression sickness is an important occupational risk for individuals with a large right-to-left shunt when working in hyperbaric air, but the manifestations of decompression sickness differ in those who decompress whilst breathing oxygen compared with those who decompress whilst breathing air. [ABSTRACT FROM AUTHOR]

Introduction: Hyperbaric chamber ventilation (HCV) refers to the intentional introduction of fresh gas, whether air, oxygen, or heliox, into a pressurised hyperbaric chamber in order to remove stale or otherwise compromised gas. The minimum required continuous HCV rate is usually determined by mathematical models derived from the contaminant mass balance within a well-stirred compartment. Non-uniform contaminant distribution patterns inside a hyperbaric chamber could emerge and invalidate the predictions of well-stirred models. Methods: Contaminant distribution was investigated inside a clinical hyperbaric chamber with the aim of comparing wellstirred model predictions with the actual contaminant concentration measurements. Results: Local ventilation effectiveness inside a clinical hyperbaric chamber may be compromised, leading to higher contaminant concentration values compared to the predictions of a mathematical model with a well-stirred assumption. Conclusions: A well-stirred assumption in mathematical models is a useful simplification that allows reasonably accurate estimates of HCV requirements. However, local ventilation effectiveness values in a particular hyperbaric chamber might vary, with the potential for hazardous contaminant accumulation in under-ventilated zones. [ABSTRACT FROM AUTHOR]

Maintaining a stable oxygen content during the hyperbaric exposure process with breathing air is important for the safety of divers and for diving equipment. This paper presents an analysis of the ability of a measurement system selected for testing1 to control the oxygen content in the breathing atmosphere of a hyperbaric facility. The measurement system was qualified according to the requirements of the supervised process. The evaluation of the measuring system selected for tests, designed to control the oxygen content with the use of MSA procedures2 was carried out in KTPP AMW3 for the DKGN-120 complex4. [ABSTRACT FROM AUTHOR]

Background: Snakebites are the main responsible for envenoming in dogs and the bothropic venom remains the most common in Brazil, which can induce a necrotic skin wound. Hyperbaric oxygen therapy (HBOT) use 100% oxygen under high pressure and used to treat different wounds in human patients. To the authors’ knowledge, no reports regarding to use the HBOT in skin wound caused by snakebite (Bothrops jararaca) are present in the literature. The present clinical case aimed to describe the use of HBOT for the treatment of an extensive necrotic wound caused by jararaca snakebite in a dog. Case: A neutered 8-year-old mixed-breed dog, weighing 12 kg, was admitted with a 7-day history of extensive necrotic wound was identified in the face and neck causing by a snakebite, and no sign of pain. The procedure of HBOT (single sessions of 1.5 ATM, 45 min, repeated every 48 h, up to 12 sessions) was decided, and the complete blood cells, alanine aminotransferase, creatinine, creatine kinase, prothrombin time, activated partial thromboplastin time, wound clinical evaluation were measured at the following time-points: 2nd, 5th, 10th, and 12th sessions. At the 5th session was identified leukopenia, neutropenia and lymphopenia. Wound re-epithelialization was initiated after the 5th session, and the complete epithelialization was identified at the 12th session of HBOT. During the HBOT no side effects were identified. Three months after the HBOT finished, the animal returned to the clinic and the clinical status evolved positively, and the wound was completed healed. Discussion: This report described the treatment of an extensive necrotic skin wound caused by snakebite (Bothrops jararaca) in an 8-year-old, neutered, mixed-breed dog using the HBOT. The wound healing was achieved after 12 sessions, similar to the literature, which reported a ranging from 1 to 12 sessions. The HBOT protocol used in this case was similar as reported for human patients with chronic wounds due to the lack of HBOT protocols for animals. No reports regarding the use of HBOT for treat necrotic wound caused by snakebite was described in the literature, and to the authors’ knowledge, this is the first report in Brazil describing the use of HBOT in dogs. On the other hand, dogs with surgically induced skin wounds and treated with daily session of HBOT using the treatment protocol of 1.7 ATM (30 min) and 2.0 ATM (40 min) up to 7th day of treatment did not show significant results on healing [9]. This fact was associated with the HBOT achievement in the proliferative and remodeling phases of the healing process. The high intensity of HBOT was between the 5th and 10th session since the wound showed a higher area decrease rate and consequently increase of wound contraction. This period was corresponding to the 10th and 20th day of the healing process, which can be identified angiogenic activity, re-epithelialization, and collagen maturation. The decrease in PVC has been associated with the anticoagulant and/or hemorrhagic activity caused by the venom, and leukopenia, neutropenia and lymphopenia was related with possible bone marrow exhaustion. Single sessions of HBOT (1.5 ATM, 45 min, and repeat each 48 h, up to 12 session) induces healing of necrotic wound caused by snakebite (Bothrops jararaca) in an 8-year-old, neutered, mixed-breed dog without any side effects. [ABSTRACT FROM AUTHOR]

Introduction: We have previously shown that hyperbaric oxygen treatment (HBOT) increased insulin sensitivity in men who were obese or overweight, both with and without type 2 diabetes. The aim of this study was to test whether this insulinsensitising effect is seen in hyperbaric air (HA). Methods: Men with type 2 diabetes who were obese or overweight were randomised to two groups: HBOT (n = 13) or HA (n = 11). A hyperinsulinaemic euglycaemic glucose clamp (80 mU·m-2·min-1) was performed at baseline and during hyperbaric intervention. Both groups were compressed to 203 kPa (two atmospheres absolute) for 90 minutes followed by a linear 30-minute decompression. The HBOT group breathed oxygen via a hood while the HA group breathed chamber air. Insulin sensitivity was assessed from the glucose infusion rate (GIR) during the last 30 minutes in the hyperbaric chamber (SS1) and the first 30 minutes after exit (SS2). Data were analysed for within-group effect by paired student t-test and between-group effect by one-way ANOVA. Results: HBOT increased GIR by a mean 26% at SS1 (P = 0.04) and 23% at SS2 (P = 0.018). There was no significant change in GIR during or after HA. A between-group effect was evident for the change in GIR at SS1 in HBOT vs HA (P = 0.036). Conclusions: The pathway by which insulin sensitivity is increased in men with type 2 diabetes requires the high oxygen partial pressures of HBOT and should be further investigated. Insulin sensitivity was not changed in hyperbaric air. [ABSTRACT FROM AUTHOR]

Introduction: Healthcare acquired infections (HAIs) are associated with increased mortality, morbidity and prolonged hospital stays. Microbiological contamination of the hospital environment directly contributes to HAIs. Optimising environmental cleaning reduces transmission of HAIs. The hyperbaric chamber poses a specific challenge for infection control as certain disinfectants and alcohol-based hand sanitisers are prohibited due to fire risk. Patients often possess multiple risk factors for HAIs. This study compared the bacteria remaining on a surface (bioburden) after a standard clean and after adjunctive disinfection with an ultraviolet-C (UV-C) robot. Methods: Internal hyperbaric chamber surfaces were first manually cleaned with Clinell® universal wipes and the floor was mopped with Whiteley neutral detergent. Allocated surfaces were swabbed using sterile cotton swabs and processed using a standard microbial culture and a bacteria-specific rapid metabolic assay. Bacterial contamination was also measured by direct contact plating on flat surfaces. The plexiglass ports were covered to protect from potential UV-C mediated damage and used as a negative control. A UV-C disinfection robot was then used to disinfect the chamber for 30 min, whereafter surfaces were swabbed again. Results: There was a significantly greater mean reduction in bioburden following adjunctive UV-C disinfection than with standard cleaning alone. The surfaces not routinely manually cleaned (e.g., bench, phone) showed greatest reduction in bacterial load following UV-C cleaning. Conclusions: There was a significant reduction in the bacterial load in the chamber following an adjunctive UV-C clean compared with that of a standard clean. Adjunctive cleaning of the hyperbaric chamber environment with a non-touch UV-C device shows promise as a method to reduce HAIs. [ABSTRACT FROM AUTHOR]

The present paper will be focused on analyzing the factors that influence indoor air qualityof the ship cabins and the hyperbaric chambers taking into account the specific degree of pollution, as oxidation of metal surfaces, vaporization, nature of the paints used, respiration, gases or particles coming from the combustion of fuels, chemicals, and allergens. The article will present a synthesis of the influence of characteristic parameters, such as ventilation rate and exposure to mold or chemicals on indoor air quality, as this is strictly and directly related to health, comfort, and ability to work. [ABSTRACT FROM AUTHOR]

Previous cases of dental barotrauma have been reported in pilots and divers. We report a case of dental barotrauma and barodontalgia in a diving physician accompanying patients during hyperbaric oxygen treatment, and due to pressure changes in the hyperbaric chamber. The physician developed sharp pain localised to the right maxillary molars but radiating to the face, ear and head during decompression from 243 kPa (2.4 atmospheres absolute). The pain intensifi ed following completion of decompression and was consistent with irreversible pulpitis. Clinical examination and panoramic radiography suggested fracture of a heavily restored tooth due to barotrauma. This was managed by tooth extraction. The physician subsequently discontinued accompanying the patients during their hyperbaric oxygen treatment sessions. Dentists and maxillofacial surgery specialists suggest waiting for a minimum of four weeks or until the tooth socket and/or oral tissue has healed suffi ciently to minimise the risk of infection or further trauma before exposure to further pressure change. Although seemingly rare, and despite the comparatively slow pressure changes, dental barotrauma can occur in hyperbaric chamber occupants. [ABSTRACT FROM AUTHOR]

A key factor affecting survival of fish captured from depth and subsequently released is barotrauma – a suite of injuries caused by expanding swim bladder gas and formation of gas embolisms resulting from the decreasing ambient pressure experienced during capture. Mulloway (Argyrosomus japonicus) are an economically-important fishery species in southern Australia often released from deep-water capture suffering from barotrauma. Hyperbaric chambers were therefore used to simulate various catch and release (C&R) scenarios on A. japonicus which allowed the influences of capture depth, surface duration and repressurization on survival and behaviour to be examined in a controlled environment combined with long-term monitoring post-simulation. In Experiment 1, simulated C&R from an acclimation pressure equivalent to 10, 30 or 50 m depth (n = 24 per depth) with a 2 min surface interval resulted in 8% mortality from 10 m increasing to 46 and 50% mortality from 30 and 50 m respectively; mortality delayed by an average of 64 d (range 5–219 d). A second C&R simulation depressurized A. japonicus individuals from either 10 or 30 m – followed by either repressurization after 10 min (Group R), or no repressurization (Group S) (n = 8 for each group). There was 0% mortality from 10 m for both groups, but from 30 m mortality was 100% for Group S and 88% for Group R. All Group S mortality and 38% of Group R mortality was immediate (<10 min), the remaining 50% of Group R mortality delayed by an average of 21 d. Barotrauma symptoms also increased in severity with increasing depth and surface interval. Immediate mortality was consistent with the formation of gas embolisms in tissues, whereas delayed mortality was likely caused by declining physical condition resulting from loss of buoyancy control caused by gas escape via swim bladder perforation and body wall rupture. Results from these experiments show the potential for delayed mortality in barotrauma-affected A. japonicus to be considerable even when successfully repressurized, casting substantial doubt over the suitability of A. japonicus as a deep-water C&R target species. • Hyperbaric chambers were used to induce barotrauma in Argyrosomus japonicus. • Immediate mortality of up to 100% was likely caused by formation of gas embolisms. • Delayed mortality of up to 50% was consistent with loss of buoyancy control. • The potential for delayed mortality was considerable even when repressurized. • A. japonicus may not be suitable as a deep-water catch-and-release target species. [ABSTRACT FROM AUTHOR]

Introduction: During a hyperbaric oxygen therapy (HBOT) session, every medical device that is used within the hyperbaric chamber is exposed to several hazards, including an increased ambient pressure and partial pressure of oxygen. In Europe, all medical devices marketed and/or sold for use in hyperbaric conditions must be tested by the manufacturer and marked 'CE' if approved. At the moment, no left ventricular assist device (LVAD) has been formally approved and CE-marked for HBOT. Case: A 65-year-old male was referred to our Hyperbaric Centre for HBOT due to a persistent life-threating soft tissue infection of the non-removable wire connecting the external controller with the pump implanted into the left ventricle of the heart (Heartware LVAD). The aim of the intervention reported here was to safely conduct HBOT sessions with this non- CE marked medical device. After risk analysis, the decision was made to isolate the external part of the LVAD (controller and batteries) from the ambient conditions in the hyperbaric chamber by placing it in a pressure-resistant housing that was vented to the external atmosphere. The housing, a 'Hyperbaric Protective Tube' was built and tested, and the resulting operating procedures were practiced by personnel involved in the patient's care. Thirty uneventful HBOT standard sessions were conducted with subsequent clinical improvement of the soft tissue infection, resulting in an extended timeframe for awaiting heart transplantation. Conclusion: An isolation housing that vents into the dumping system of the hyperbaric chamber allows for the safe use of critical medical devices without prior testing for their compatibility with the hyperbaric environment. [ABSTRACT FROM AUTHOR]

Abstract A key factor affecting survival of fish which are captured at depth and subsequently released is barotrauma. Barotrauma are a suite of injuries which occur as a result of the decreasing ambient pressure experienced by a fish during capture and are caused by expanding swim bladder gas and formation of gas embolisms. Snapper (Chrysophrys auratus) are of key importance to both commercial and recreational fisheries in southern Australia and are often released after capture suffering from barotrauma. Previous research has yielded inconsistent results for survival of C. auratus after suffering barotrauma, in part due to influences related to capture, 'cage' effects and the use of only very short term post-catch and release monitoring. This study therefore used laboratory hyperbaric chambers to simulate the pressure changes associated with capture to investigate whether barotrauma was a direct cause of mortality in C. auratus. The influences of depth and repressurization on mortality, behaviour and symptoms due to barotrauma could therefore be examined in a controlled environment independent of capture and 'cage' effects combined with long-term monitoring (220 d) post-simulation. In a pilot experiment C. auratus (n = 12) were depressurized from 8 bar (≈70 m depth), before being repressurized after 2 min at 1 bar (atmospheric pressure) resulting in agitated in-chamber behaviours and abdominal distension as a result of swim bladder perforation, but 100% survival. A second experiment depressurized C. auratus from 4 bar (≈30 m depth); one treatment group (n = 32) were repressurized after 10 min again resulting in behaviour and symptoms indicative of swim bladder perforation and 100% survival, the other group (n = 32) was left at 1 bar and exhibited many additional external and internal barotrauma symptoms and suffered 16% mortality. Despite the death of a single control individual, statistical analyses found a significant effect of treatment on mortality. Mortality occurred within 15 min of depressurization and the cause of death was consistent with the formation of gas embolisms. Staged post-mortems performed on C. auratus that had been depressurized from 4 bar to induce swim bladder perforation indicated that swim bladders were healed sufficiently to hold gas after just 2 d. C. auratus were shown to be a remarkably robust species to the effects of barotrauma, particularly if repressurized quickly (<10 min) after capture and this resilience is likely reflective of their characteristic semi-pelagic physiology. This study also demonstrated the usefulness of laboratory hyperbaric chambers to examine the long term (>200 d) effects of depressurization on deep water fish species independent of capture and 'cage' effects. [ABSTRACT FROM AUTHOR]

A type of improved device, designated as inward integral buckle arrestor, is introduced for the pipe-in-pipe (PIP) systems. The experiments have been performed to reproduce the buckle propagation and crossover scenarios of the PIP installed with such devices in a hyperbaric chamber under external pressure. Based upon the experimental observations, dedicated finite element models for test specimens are developed to simulate the whole process of a propagating buckle crossing over an inward integral arrestor to the downstream PIP under the quasi-static, steady-state conditions. Through extensive parametric dependence analyses, the potential buckle propagation and crossover modes are identified, and a reasonable empirical formula of the crossover pressure of the arrestors for the PIP systems is established. The corresponding empirical design formula and lower bound envelope line are proposed to estimate the arresting efficiency of such devices in the preliminary design stage. [ABSTRACT FROM AUTHOR]

Objective: An analysis of factors that may indicate both the type and degree of dehydration of a diver's body following a dry chamber hyperbaric exposure. Methods: The study was participated by 63 men - professional divers, with extensive diving experience, aged 24-51 years (average age 32.6). The subjects underwent two hyperbaric exposures, one to a pressure of 0.3 MPa and one to a pressure of 0.6 MPa, with oxygen decompression. The exposures were carried out in a hyperbaric chamber pursuant to the decompression tables of the Polish Navy, with the observance of a 24-hour interval between exposures. Blood samples were collected from the participants in order to perform a blood morphology test. Body weight was measured with the bioelectrical impedance method using the Maltron BioScan 920 device. The results were subjected to statistical analysis. The following blood morphology parameters were analyzed: hematocrit (Ht), erythrocyte size (MCV), color index (MCHC) and body weight composition: total water (TBW), extracellular water (ECW), intracellular water (ICW). Results: The studies have shown that during a hyperbaric exposure in the chamber the diver's body becomes dehydrated, with observable loss of both intracellular water as evidenced by the reduction of hematocrit content and erythrocyte size, as well as extracellular water, with the accompanying increase in the color index. Conclusions: Hyperbaric conditions are conducive to the dehydration of the diver's body, however to a degree which does not lead to an occurrence of health hazards. Good care for one's health through proper nutrition and hydration are sufficient preventive and protective measures. [ABSTRACT FROM AUTHOR]

Objectives: Hyperbaric oxygen (HBO2) exposure may enhance cardiorespiratory fitness. Exercise training and HBO2 exposure stimulate mitochondrial biogenesis, increase capillary density, and induce adaptive antioxidant mechanisms. We hypothesized that an exercise regimen of sprint interval training (SIT) while breathing HBO2 would lead to a greater improvement in exercise performance compared to the same training breathing ambient air. Methods: Healthy long-term intermediate-altitude residents, ages 20-39 years, with normal spirometry and cardiorespiratory fitness were randomized to two groups: one performing six sessions of an SIT regimen over two weeks in a hyperbaric chamber (1.4 ATA [141.9 kPa], FiO2=1.0); the other performing under ambient pressure conditions (0.85 ATA [86.1 kPa], FiO2=0.21). Training effect was evaluated by comparing incremental cycle ergometry cardiopulmonary exercise testing before and after the training regimen. The primary outcome measure was peak oxygen consumption (VO2), while secondary outcomes included additional exercise parameters. The effect of study group on exercise parameters was assessed using two-factor repeated measures ANOVA. Results: Of 58 participants randomized, 49 completed the training program and all cardiopulmonary exercise tests (n=23 HBO2, n=26 ambient). Both groups experienced an increase in peak VO2: 8.1% HBO2 and 7.1% ambient; the differences were not significant (p=0.50). Secondary parameters of peak work rate and peak VE experienced a significantly higher change in the HBO2 group compared to the ambient group (p=0.05 and p=0.03, respectively). Conclusion: Cardiorespiratory fitness improved after a two-week SIT regimen, but improvement in peak VO2 was not significantly different between ambient and HBO2 groups. [ABSTRACT FROM AUTHOR]

Middle ear barotrauma (MEB), one of the side effects of hyperbaric oxygen (HBO2) therapy, sometimes cannot be directly diagnosed during the therapy itself. Instead, its incidence and degree are judged based on subjective statements made by patients when in conversation with medical staff regarding how they feel. To prevent MEB in practice it is proposed that the tympanic membrane evaluation system and automatic control chamber developed in a previous study be applied as part of a prevention algorithm [16]. The proposed algorithm, which determines and equalizes the unbalanced pressure of a subject based on their tympanic admittance, was evaluated in conjunction with conventional HBO2 therapy in an experiment involving 100 subjects. Among the 50 subjects in the control group who received HBO2 therapy 16 subjects experienced MEB. In contrast, the experimental group of 50 subjects were treated with a hyperbaric chamber protocol incorporating the automatic control system and proposed algorithm. At the conclusion of the treatment, no subjects exhibited middle ear barotrauma. In the case of the control group, while the target pressure was achieved, middle ear barotrauma still occurred. However, in the case of the experimental group, the pressure inside the chamber was adjusted as per the algorithm, which allowed the target pressure for every subject to be achieved without experiencing MEB. When a particular subject was unable to perform any pressure equalization method such as swallowing or the Valsalva maneuver, the chamber was not pressurized based on the tympanic admittance and thus no MEB occurred. [ABSTRACT FROM AUTHOR]

Introduction: Symptomatic Eustachian tube dysfunction (ETD) and middle ear barotrauma (MEB) are the most common reported complications during hyperbaric oxygen (HBO2) treatment. There is no standardized rate of compression (ROC) reported to decrease the incidence rates of ETD and MEB during hyperbaric treatments. Few studies actually demonstrate that the ROC decreases the incidence of ETD or MEB. Methods: Our study was designed to determine an optimal hyperbaric chamber compression rate that might reduce the incidence of symptomatic ETD leading to MEB during the compression phase of treatment in a multiplace hyperbaric chamber. Data was collected prospectively over 2,807 elective patient treatments compressed using a U.S. Navy Treatment Table 9 (USN TT9) with a modified ROC. ROC was assigned using two variables, time (10 vs.15 minutes) and slope (linear vs. non-linear compression). Patients were exposed to all four compression schedules in a consecutive daily fashion. We recorded any patient requiring a stop during initial compression due to ear discomfort. Anyone requiring a stop was evaluated post treatment for MEB. Findings were compared to our standard 10-minute linear ROC. Evaluation of the tympanic membrane was accomplished using video otoscopy. Barotrauma when present was classified using both the Teed and O'Neill grading systems. Data was analyzed using basic statistical methods. Results: When comparing four different rates of compression during an elective USN TT9 in a multiplace (Class A) chamber there is a decreased incidence for symptomatic ETD when using a 15-minute linear compression schedule (p-value < 0.05). Conclusion: Using a 15-minute linear compression schedule is associated with less symptomatic ETD and less MEB when performing an elective 45 fsw (USN TT9) hyperbaric treatment in a Class A chamber. Asymptomatic ETD and MEB were not considered in this study. [ABSTRACT FROM AUTHOR]

Abstract The efficacy of hyperbaric cold storage for preserving lean fish has been recently demonstrated but, to the best of our knowledge, no data exist for fatty fish. To evaluate the effect of hyperbaric cold storage on the shelf-life and quality of fatty fish, we stored Atlantic mackerel fillets at 5 °C, both at atmospheric pressure and at 50 MPa. After 12 days of hyperbaric storage, no microbial growth was observed. Thus, most counts were similar or slightly lower than those of control samples at day 0, while H 2 S-producing organisms and sulphite-reducing bacteria reduced under the detection limits. Moreover, no significant lipid degradation was observed. By contrast, increased microbial counts and significant lipid hydrolysis were detected in the samples stored at atmospheric pressure. Moreover, even though the protein profile was significantly altered during hyperbaric storage, most fish-quality indicators (pH, TVB-N, drip loss, water-holding capacity, and firmness after cooking) were better preserved in the mackerel samples stored at 50 MPa. These results clearly prove that hyperbaric cold storage was more efficient than conventional refrigeration for the preservation of Atlantic mackerel fillets. Industrial relevance Long-term preservation of fatty fish is a challenge for the seafood industry mainly due to lipid degradation that can rapidly reduce fish quality. If effective against lipid degradation, hyperbaric cold storage could be an interesting technology to preserve fish and fish products. The increased cost resulting from hyperbaric storage should be overcome by an extended shelf-life of a high-quality product. Highlights • Cold storage was more effective at 50 MPa than at atmospheric pressure for preserving the mackerel quality. • Microbial counts did not increase after 12 days of hyperbaric cold storage at 50 MPa. • Unlike in AP_CS samples, no lipid degradation occurred in HP_CS samples. • Cold storage at 50 MPa significantly affected sarcoplasmic and myofibrillar proteins. • pH, TVB-N, drip loss, WHC, and firmness after cooking were better preserved at 50 MPa. [ABSTRACT FROM AUTHOR]

Abstract Limited experimental and field data are available describing oil droplet formation from subsea releases at high pressure. There are also analytical challenges quantifying oil droplets over a wide size and concentrations range at high pressure. This study quantified oil droplets released from an orifice in seawater at low and high pressure (5 m and 1750 m depth). Oil droplet sizes were quantified using a newly developed sensor (Silhouette camera or SilCam). The droplet sizes measured during experiments at low and high pressure, using the same release conditions, showed no significant difference as a function of pressure. This lack of a pressure effect on oil droplet sizes was observed for both untreated oil and for droplet formation during subsea dispersant injection or SSDI. This strongly indicates that the effectiveness of SSDI is not influenced by water depth or pressure, at least for simulated subsea releases of oil alone (no gas). Highlights • Limited data exists on oil droplet formation from subsea releases at high pressure. • Experiments were performed at pressure corresponding to 5 and 1750 m depth. • No significant difference in oil droplets sizes was observed at high & low pressure. • This was also observed during dispersant injection (1 & 2% dosage). • This indicates that dispersant injection effectiveness is not dependant on pressure. [ABSTRACT FROM AUTHOR]

The main aim of this paper was to characterize the Autonomic Nervous System response in hyperbaric environments using electrocardiogram (ECG) and pulse-photoplethysmogram (PPG) signals. To that end, 26 subjects were introduced into a hyperbaric chamber and five stages with different atmospheric pressures (1 atm; descent to 3 and 5 atm; ascent to 3 and 1 atm) were recorded. Respiratory information was extracted from the ECG and PPG signals and a combined respiratory rate was studied. This information was also used to analyze Heart Rate Variability (HRV) and Pulse Rate Variability (PRV). The database was cleaned by eliminating those cases where the respiratory rate dropped into the low frequency band (LF: 0.04–0.15 Hz) and those in which there was a discrepancy between the respiratory rates estimated using the ECG and PPG signals. Classical temporal and frequency indices were calculated in such cases. The ECG results showed a time-related dependency, with the heart rate and sympathetic markers (normalized power in LF and LF/HF ratio) decreasing as more time was spent inside the hyperbaric environment. A dependence between the atmospheric pressure and the parasympathetic response, as reflected in the high-frequency band power (HF: 0.15–0.40 Hz), was also found, with power increasing with atmospheric pressure. The combined respiratory rate also reached a maximum in the deepest stage; thus, highlighting a significant difference between this stage and the first one. The PPG data gave similar findings and also allowed the oxygen saturation to be computed; therefore, we propose the use of this signal for future studies in hyperbaric environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: Decompression sickness is a condition th a t results from an abrupt change from a higher to a lower pressure. It is described most commonly in divers; however, it can occur in aviation incidents, which this case report will discuss. CASE REPORT: Following an acute cabin depressurization incident, 36 patients presented to a small outpatient clinic with multiple symptoms, including fatigue, headache, nausea, vomiting, and dizziness. These patients were evaluated, triaged, and some were able to be successfully treated with supplemental oxygen in clinic. Eight of the patients had symptoms that were either persistent or concerning enough that they were referred to the dive medical clinic, where the dive medical team diagnosed six of the patients with Type II decompression sickness and referred them for hyperbaric oxygen chamber therapy. All patients who received hyperbaric therapy experienced at least some relief of symptoms, with most reporting some residual fatigue after the therapy. DISCUSSION: This case provided both lessons in triage and management of multiple patients in a small outpatient clinic, as well as the challenges in making the diagnosis of decompression sickness. [ABSTRACT FROM AUTHOR]

Collapse of the inner pipe of a pipe-in-pipe (PIP) system under external pressure is studied experimentally and numerically herein. Hyperbaric chamber test results of three PIP systems with identical inner pipes and different outer pipes are presented. It is observed that the geometric and material properties of the outer pipe affect the collapse pressure of the inner pipe. Using validated finite element analyses (FEA), a parametric study is conducted and collapse mechanisms of PIPs with various combinations of outer and inner pipes with practical range of diameter-to-thickness ratios ( D / t ) between 15 and 40 are discussed. Empirical expressions are proposed for the collapse pressure of the inner pipe ( P ci ), and its upper and lower bounds. The proposed empirical equation for P ci , is shown to agree well with the experimental results of the tested PIPs. Moreover, two distinctive modes of collapse in the inner pipe are identified and discussed. [ABSTRACT FROM AUTHOR]

This work presents the automation of a multiplace hyperbaric chamber. It includes the system modeling, identification, controller calculation and system validation. With the proposed approach a good pressure profile tracking and repeatability are achieved. Moreover, the proposed automation includes the implementation of powerful treatment tools such as Pause and Alleviation procedures. The control system implemented is based on a special zero-pole cancellation regulator. Experimental results are provided to illustrate the behavior of the automated chamber. It is important to remark that the chamber automated in this work is being successfully used in a real hospital since 2015 treating more than 40 patients per day, five days a week. [ABSTRACT FROM AUTHOR]

Ice-free vitreous cryopreservation (vitrification) is regarded as the principal method for avoiding ice crystallization damage in cryopreserved tissues and organs. We previously established the fundamental thermodynamics of isochoric (constant volume) systems for cryopreservation, and now extend this novel approach to vitrification in an isochoric system. This was achieved by measuring pressure changes in a 2 ml isochoric chamber containing a variety of aqueous solutions of the ubiquitous cryoprotective additives (CPA), dimethyl sulfoxide (Me 2 SO) and Propane-diol. The CPAs, ranging in concentrations from 0 to 49%(w/v), were prepared in a proprietary preservation solution (Unisol ® ) in anticipation of future applications to tissue and organ banking. Pressures developed in the system were monitored as a function of CPA concentration and cooling rate when the isochoric chamber was cooled to cryogenic temperature (−160 °C). This study corroborated our previous findings that pressure increases in accordance with the thermodynamics of partially frozen systems of low concentrations of CPAs. A key finding of this study was that in an isochoric system of higher concentrations of CPA, which vitrifies, there is no increase in pressure. In fact, an increase in pressure is a measure of failure to vitrify and a measure of devitrification. Comparison with results from the literature show that the concentration of CPAs needed for vitrification in an isochoric chamber is substantially lower than that needed for vitrification in isobaric systems at 1 atm and hyperbaric systems at 1000 atm. In addition, isochoric chambers are much more effective in promoting vitrification than hyperbaric pressure chambers, and are less expensive, easier to design, and implement. [ABSTRACT FROM AUTHOR]

Introduction: The main pathologies that require a recompression therapy are decompression sickness (DCS) and arterial gas embolism (AGE), boths can be caused by pressure-related activites and certain amount of gas (dissolved or not) in the Victim's blood. Besides diving other pressure-related activities put the person in risk of this pathologies. Aim: To investigate the main place of production of these pathologies and their physiological base. Methods: we reviewed all charts of patients with DCS and AGE from 1970-2017 at Centro de Buceo de la Armada (Cartagena). Results: There were 392 cases, 345 (88%) diving related, 36 (9,18%) hyperbaric chamber-related, 6 (1,53%) submarine activities related and 4 (1,02%) hypobaric activities-related. Conclusions: Diving injuries rates are the most important but any pressure-related activity can be risky even hyperbaric chamber activity, considered the safest pressure-related activity. [ABSTRACT FROM AUTHOR]

Introduction: The management of mechanically ventilated patients in the hyperbaric environment requires knowledge of how the physical properties of gases change under pressure and how this affects the operation of the ventilator. The primary objective of this study was to test the performance of the Dräger Oxylog 1000® ventilator in a hyperbaric environment. Methods: Each of two ventilators was connected to a mechanical test lung system with an in-built pressure gauge. We used a Wright's respirometer to measure the tidal volumes. The same ventilator settings were tested under varying environmental pressures from ambient (101.3 kPa) to 18 meters' sea water (284 kPa) in a multiplace hyperbaric chamber. Results: A decrease was found in tidal volume, decrease in airway pressure and increase in respiratory rate delivered by the Dräger Oxylog 1000 portable ventilator with increasing pressures to 284 kPa. Discussion: These findings can be explained by the operating principles of the Oxylog 1000, which is a time-controlled, constant-volume ventilator that functions as a flow chopper. Even between the two Oxylog 1000 ventilators tested there were different absolute changes in tidal volume, airway pressures and respiratory rates at various depths. Hence, the trend of changes in these variables is probably more important than absolute values. Conclusion: In summary, understanding the trend of changes in ventilator variables will allow clinicians to make appropriate corrections in ventilator settings and carefully monitor adequacy of ventilation to prevent adverse ventilator-associated events. The Dräger Oxylog 1000 portable ventilator is an adequate back-up ventilator for use with straight-forward, ventilatordependent patients undergoing hyperbaric treatment. [ABSTRACT FROM AUTHOR]

Propagation buckling mechanisms in pipe-in-pipe (PIP) systems with thin and moderately thin carrier pipes with a diameter-to-thickness ( D o /t o ) ratio in the range 26–40 are investigated using 2D analytical and 3D nonlinear (material and geometry) finite element (FE) models. The FE models are validated against hyperbaric chamber tests of a PIP system with D o /t o of 30. Using the validated FE model a parametric study is conducted and two distinct buckle propagation modes in PIPs are observed. Empirical expressions for each mode are proposed and are found to be different from previous expressions suggested for PIPs with ( D o /t o ) ratio in the range 15–25. [ABSTRACT FROM AUTHOR]

The article presents information on the impact of residential fires on the pets, as they get injured and inhale excess smoke, highlighting the treatment procedures required for them which includes hyperbaric oxygen chambers for smoke inhalation. Topics include the emergency response services for pets, involvement of the Red Paw Emergency relief team, and use of oxygen masks on pets with critical injuries.

The climate conditioning of a hyperbaric chamber is extremely important, as the health or even lives of the divers depend on it. Climate conditioning consists of controlling and maintaining the following factors inside the enclosure: • Temperature • Humidity • The parameters of the breathing gas. In this paper I have analyzed some of the aspects regarding the thermo-hygrometric phenomena and the composition of the breathing gas mix, phenomena that accompany any dive in saturation. The variation in temperature and humidity under pressure and during decompression differs from the unitary dives with Nitrox, because of helium, the main component of breathing gas. When planning the dive, one must take into account the presence of atmospheric air in the hyperbaric chamber at the beginning of the compression process, in order to avoid hyperoxia. [ABSTRACT FROM AUTHOR]

Objectives: To validate the effects of the new plateau hyperbaric chamber on alleviating high altitude hypoxia on Mount Kun Lun.Methods: A prospective, controlled study of rabbits and adult volunteers was conducted at altitudes of 355, 2880 and 4532m. We obtained arterial blood samples from rabbits and volunteers before and after hyperbaric treatment. The respiratory rate, heart rate, and blood pressure (BP) of adult volunteers were monitored during hyperbaric treatment.Results: The mean PaO2 levels of experimental group rabbits and volunteers increased significantly after 60min of hyperbaric treatment at 350, 2880 and 4532m. The mean PaCO2 and pH levels of rabbits were not significant different before and after hyperbaric treatment at each altitude. The mean PaCO2 and pH levels were not significant different at 355m in the human study. However, at 2880 and 4532m, pH fell with increasing PaCO2 levels in humans before and after hyperbaric treatment.Conclusions: The new multiplace plateau hyperbaric chamber may be used to alleviate plateau hypoxia by increasing patient PaO2. However, its value in treating AMS must be confirmed in field conditions. [ABSTRACT FROM AUTHOR]

Hyperbaric storage (HS) of raw watermelon juice, at 50, 62.5 and 75 MPa, at temperatures of 10, 15 and ≈25 °C (room temperature, RT), was studied to evaluate shelf-life comparatively to refrigeration (RF, 4 °C). Generally, RF caused an increase of microbial loads to values ≥6.0 log CFU/mL after 7 days of storage. Contrarily, HS at 62.5/75 MPa (15 °C) showed a reduction of initial loads, by at least 2.5 log CFU/mL, up to 58 days, while pH and colour values did not changed under these HS conditions. Additionally, the combination of a lower temperature with HS has beneficial effects to control microbial development, particularly for the lower pressure studied (50 MPa/10 °C). In conclusion, HS increased watermelon juice shelf-life for at least 58 days, indicating a great potential for future RF replacement. [ABSTRACT FROM AUTHOR]

This paper presents the replacement of a traditional wired communication link of the hyperbaric chambers with a wireless ZigBee-based system. This move allows a reduction in the costs of seals capable of withstanding the internal pressures and gives rise to a more versatile system. The new system is able to capture and process individual vital signs like the electrocardiography signal, and other analog sources, sending the data to an external computer and allowing analysis, representation and sharing with medical staff. This system solves such problems as the attenuation of the signal produced by the metal walls of the hyperbaric chamber and has a coverage area large enough to manage up to six patients with an effective data rate conversion of 2kHz. Furthermore, a battery-based and multiparameter platform is designed for multipatient hyperbaric chambers. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Unintended pump insulin delivery was reported to occur as a consequence of decreased atmospheric pressure, probably mediated by air bubble formation and the expansion of existing bubbles. This observation has been used to explain some hypoglycemic episodes occurring in patients on insulin pump treatment in between 1 and 1 h 45 min after the flight takeoff. New models of insulin pumps have been introduced in the market, most of them are waterproof certified. It is not clear if in these new pumps the influence of atmospheric pressure changes on the insulin delivery is still present. Moreover, there are no evidences related to the insulin pump operations in hyperbaric conditions, like as during diving activities. Our aim is therefore to verify the eventual variation of insulin pump delivery determined by atmospheric pressure changes in hyperbaric conditions.Methods: Three new models of insulin pumps were tested in hyperbaric conditions at a flow rate of 2 U/h.Results: Atmospheric pressure variation affected pump insulin release. An increase in the atmospheric pressure from 1 to 1.3 atmosphere (ATA) induced a decrease of pump basal insulin release (about -0.2 U/10 min); conversely, when the atmospheric pressure returned from 1.3 to 1 ATA, an unintended insulin delivery was observed (about +0.3 U/10 min). This phenomenon appeared to be independent of the insulin pump rate and dependent on the presence of air bubbles within the insulin tube setting and cartridge.Conclusions: Unintended insulin delivery driven by atmospheric pressure changes in hyperbaric conditions occurred in the new insulin pumps available. Patients should pay attention to possible variation of insulin rate during the flight or during diving activities. [ABSTRACT FROM AUTHOR]

To determine the effect of pressure variations on the retention of prosthetic crowns, 36 identical, cast metal crowns were fixed to simulated, epoxy resin crown preparations with zinc oxyphosphate cement. Eighteen specimens were placed in a hyperbaric chamber and subjected to 15 cycles of simulated immersion at 30 m and decompression, as usually carried out by scuba divers. The untreated specimens served as controls. When the force required to dislodge the crowns was measured, the treated crowns were dislodged at about one third the load that was required to dislodge the control group, indicating that a statistically significant decrease in cement strength follows pressure variations. [ABSTRACT FROM AUTHOR]

This paper presents a wireless system to send biosignals outside a hyperbaric chamber avoiding wires going through the chamber walls. Hyperbaric chambers are becoming more and more common due to new indications of hyperbaric oxygen treatments. Metallic walls physically isolate patients inside the chamber, where getting a patient’s vital signs turns into a painstaking task. The paper proposes using a ZigBee-based network to wirelessly transmit the patient's biosignals to the outside of the chamber. In particular, a wearable battery supported device has been designed, implemented and tested. Although the implementation has been conducted to transmit the electrocardiography signal, the device can be easily adapted to consider other biosignals. [ABSTRACT FROM AUTHOR]

The probabilities of decompression sickness (DCS) among diving fishermen are higher than in any other group of divers. Diving behavior of artisanal fishermen has been directed mainly to target high-value species. The aim of this study was to learn about the occurrence of DCS derived from sea cucumber harvesting in the Yucatán Peninsula, Mexico. We conducted a retrospective chart review of diving fishermen treated at a multiplace hyperbaric chamber in Tizimín, Mexico. In total, 233 recompression therapies were rendered to 166 diving fishermen from 2014 to 2016. The average age was 36.7 ± 9.2 years (range: 20-59 years); 84.3% had experienced at least one DCS event previously. There was a correlation between age and DCS incidents (F: 8.3; R2: 0.07) and differences in the fishing depth between seasons (H: 9.99; p<0.05). Musculoskeletal pain was the most frequently reported symptom. Three divers, respectively, suffered permanent hearing loss, spinal cord injury and fatal outcome. Diving fishermen experience DCS at an alarmingly high rate, probably due to the type of species targeted, given the requirements in each case. Understanding divers' behaviors and their incentives while in pursuit of high-value species such as sea cucumber could help to find ways to mitigate health risks and help enforce regulation. [ABSTRACT FROM AUTHOR]

Context: Middle ear barotrauma (MEB) is common during chamber compression in hyperbaric oxygen therapy. However, little evidence exists on an optimal compression protocol to minimize the incidence and severity of MEB. Objective: To compare the incidence of MEB during hyperbaric oxygen therapy using two different chamber compression protocols. Design: Double-blinded, randomized controlled trial. Setting: Hyperbaric Medicine Unit, The Townsville Hospital, Queensland, Australia, September 2012 to December 2014. Patients: 100 participants undergoing their first hyperbaric oxygen therapy session. Intervention: Random assignment to a staged (n=50) or a linear (n=50) compression protocols. Photographs of tympanic membranes were taken pre- and post-treatment and then graded. Middle ear barotrauma was defined as an increase of at least one grade on a modified TEED scale. Results: The observed MEB incidence under the staged protocol was 48% compared to 62% using the linear protocol (P=0.12, exact one-sided binomial test), and thus the staged protocol did not show a significant improvement in MEB. However, the staged protocol resulted in significantly less severe deteriorations in MEB grades when compared to the linear protocol (P=0.028, exact one-sided Mann-Whitney type test). Conclusion: The use of the assessed staged compression protocol for the first hyperbaric oxygen treatment showed no significant effect on the overall incidence of MEB when compared to the gold standard linear protocol but resulted in a significant improvement in the severity of the experienced MEBs. Further studies are needed to elucidate an optimal compression protocol to minimize middle ear barotrauma. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to introduce a new method for the design of a pressure sensor in the hyperbaric environment.Design/methodology/approach The new method focuses on two vital parameters that are closely related to the output and sensitivity of the sensor. The rectangular diaphragm structure is adopted, and the piezoresistors are planted on the surface accordingly. To verify the effect of the method, a contrastive sensor chip is fabricated in a conventional way, and two types of sensor chips are tested at the same time.Findings The new method for the design of a pressure sensor is advisable and favorable. The sensor fabricated by the method possesses outstanding high sensitivity and a wide measurement range.Originality/value This paper provides a new idea for increasing the measurement range of the pressure sensor with an acceptable sacrifice of sensitivity. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate a recently developed equipment test method by assessing the safe and accurate functioning of the Abbott Optium FreeStyle H portable blood glucose monitor for use in the Alfred Hospital's hyperbaric chamber. The results of this study indicate that the test method can be used successfully to evaluate instruments and/or devices for use in the hyperbaric environment. The evaluation initially found that this particular glucose monitor contained a lithium battery which can be hazardous when used in the hyperbaric environment. However, upon further inspection it was determined the battery posed minimal risk for fire and explosion due to its small capacity and design application. The results indicate that the Abbott Optium Free-Style H blood glucose monitor operated normally when used in the hyperbaric chamber. This glucometer was found to perform within the calibration specification requirements for accuracy at all stages of a typical hyperbaric treatment and as such the Abbott Optium FreeStyle H blood glucose monitor was deemed safe for use in the hyperbaric chamber at the Alfred Hospital. [ABSTRACT FROM AUTHOR]