Hyperbaric Medicine in Pediatrics — reality of a Portuguese reference center / Medicina Hiperbárica em Pediatria — realidade de um centro de referência português

ABSTRACT Objective: To identify and characterize the population of Pediatric patients referred to our hyperbaric oxygen therapy center. Methods: Retrospective and observational study, including pediatric patients treated with hyperbaric oxygen therapy, from 2006 to 2021, at the hyperbaric medicine reference center in the north of Portugal. Variables of interest were extracted from electronic medical records. Results: Our study included 134 patients. The most frequent reasons for referral were carbon monoxide poisoning (n=59) and sudden sensorineural hearing loss (n=41). In 75 cases (56%), treatment was initiated in an urgent context. Symptom presentation at Emergency Department varied among patients, the most frequent being headache and nausea/vomiting. Concerning carbon monoxide poisoning, the most common sources were water heater, fireplace/brazier, and boiler. Regarding adverse effects, it was identified one case of intoxication by oxygen and four cases of middle ear barotrauma. Conclusions: The most frequent cause for referral was carbon monoxide poisoning. All patients evolved favorably, with few side effects being reported, emphasizing the safety of this therapy. While most pediatricians may not be aware of the potential benefits arising with hyperbaric oxygen therapy, it is of upmost importance to promote them, so that this technique is increasingly implemented.

RESUMO Objetivo: Identificar e caracterizar a população de casos pediátricos encaminhados para o nosso centro de oxigenoterapia hiperbárica. Métodos: Estudo retrospetivo e observacional, que incluiu doentes pediátricos tratados com oxigenoterapia hiperbárica, de 2006 a 2021, no centro de referência de medicina hiperbárica do norte de Portugal. As variáveis de interesse foram extraídas dos processos clínicos eletrônicos. Resultados: O nosso estudo incluiu 134 casos. Os motivos de encaminhamento mais frequentes foram intoxicação por monóxido de carbono (n=59) e surdez súbita neurossensorial (n=41). Em 75 casos (56%) o tratamento foi iniciado em contexto de urgência. Os sintomas de apresentação à admissão variaram entre os diferentes casos, sendo os mais frequentes cefaleias e náuseas/vômitos. No que diz respeito à intoxicação por monóxido de carbono, as fontes mais comuns foram o aquecedor, lareira/braseiro e caldeira. Com relação aos efeitos adversos, foram identificados um caso de intoxicação por oxigênio e quatro casos de barotrauma do ouvido médio. Conclusões: A causa mais frequente de encaminhamento foi a intoxicação por monóxido de carbono. Todos os pacientes evoluíram favoravelmente e foram registrados poucos efeitos adversos, o que enfatiza a segurança desta terapia. Uma vez que a maioria dos pediatras pode não estar informada sobre os potenciais benefícios da oxigenoterapia hiperbárica, é de extrema importância promovê-los para que esta técnica seja cada vez mais implementada.

Enhancement of cognitive function in mice with Alzheimer's disease through hyperbaric oxygen-induced activation of cellular autophagy.

Objective: In this study, we examined the effectiveness of hyperbaric oxygen (HBO) therapy in ameliorating cognitive deficits in mice with Alzheimer's disease (AD), while also assessing its impact on the autophagic pathway within the context of AD. Methods: 20 double-transgenic mice expressing the amyloid precursor protein and presenilin 1 (APP/PS1) were purposefully selected and randomly assigned to groups A and B. Concurrently, 20 C57BL/6 mice were chosen and randomly categorized into groups C and D, each consisting of 10 mice. Mice in groups B and D received HBO treatment. The Morris water maze assay was used to assess changes in mouse behavior. Immunohistochemistry techniques were used to quantify the expression levels of amyloid-beta 42 (Aß42) and microtubule-associated protein 1A/1B-light chain 3 (LC3) in hippocampal tissues, while western blot analysis was used to investigate the levels of LC3-II, p62, phosphoinositide 3-kinase (PI3K), and mammalian target of rapamycin (mTOR) proteins within hippocampal tissues. Results: Mice allocated to group B exhibited reduced escape latency and prolonged dwell time in the target quadrant compared to other groups. Histological examination revealed conspicuous plaque-like deposits of Aß42 in the hippocampal tissues of mice in groups A and B. Group B displayed diminished Aß42-positive reactants and augmented microtubule-associated protein 1A/1B-LC3-positive reactants compared to group A. LC3-positive reactants were also detected in the hippocampal tissues of mice in groups C and D, surpassing the levels observed in groups A and B. Furthermore, group B demonstrated significantly lower expression of mTOR protein and markedly higher expression of LC3-II protein in mouse hippocampal tissues when compared to group A (P < 0.05). Conversely, there were no significant disparities noted in PI3K and p62 protein expression between groups B and A. Notably, no discernible discrepancies were observed in the expression levels of mTOR, PI3K, LC3-II, and p62 proteins between groups C and D within mouse hippocampal tissues. Conclusion: HBO treatment demonstrates efficacy in enhancing cognitive function in mice with AD and holds promise as a potential therapeutic intervention for AD by facilitating the activation of the mTOR pathway-mediated autophagy.

Effects of different treatment measures on the efficacy of diabetic foot ulcers: a network meta-analysis.

Introduction: Through a network meta-analysis, we compared different treatment measures for patients with diabetic foot ulcers (DFU), assessing their impact on the healing of DFU and ranking them accordingly. Methods: We searched the PubMed, the China National Knowledge Infrastructure (CNKI), Embase, the WanFang and the WeiPu database. The retrieval time was from database establishment to January 2024, and retrieval entailed subject and free words. Randomized controlled trials (RCTs) with different treatment measures for DFU were included. Data extraction and evaluation were based on the PRISMA guidelines. Meta-analyses using pairwise and network methods were employed to compare and rank the effectiveness of different treatments for DFU. Results: Ultimately, we included 57 RCTs involving a total of 4,826 patients with DFU. When it comes to ulcer healing rates, compared to standard of care(SOC),platelet-rich plasma(PRP), hyperbaric oxygen therapy(HBOT), topical oxygen therapy(TOT), acellular dermal matrix(ADM), and stem cells(SCs) in both direct meta-analysis(DMA) and network meta-analysis(NMA) can effectively increase the complete healing rate. For Scs+PRP, a statistically significant improvement was only observed in the NMA. Moreover, when compared to the negative pressure wound therapy(NPWT) group, the PRP+NPWT group was more effective in promoting the complete healing of ulcers. In terms of promoting the reduction of ulcer area, no statistical differences were observed among various treatment measures. When it comes to ulcer healing time, both PRP and NPWT can effectively shorten the healing time compared to SOC. Furthermore, when compared to the NPWT group, the combined treatment of PRP and ultrasonic debridement(UD) with NPWT is more effective in reducing healing time. In terms of amputation rates and adverse reactions, the PRP group effectively reduced the amputation rate and adverse reactions for patients with DFU. Additionally, compared to the NPWT group, the combined treatment of PRP and UD with NPWT reduced the incidence of adverse reactions. However, no significant differences were observed among other treatment measures in terms of amputation rates and adverse reactions. The ranking results showed that the efficacy of PRP+NPWT and UD+NPWT in promoting ulcer healing, reducing ulcer area, shortening healing time, decreasing amputation rates and adverse reactions is superior to that of the alone PRP group, NPWT group, and UD group. Conversely, the SOC group demonstrates the least effective performance in all aspects. Conclusion: Due to the particularity of the wound of DFU, the standard of care is not effective, but the new treatment scheme has a remarkable effect in many aspects. And the treatment of DFU is not a single choice, combined with a variety of methods often achieve better efficacy, and will not bring more adverse reactions.

Outcomes of Hyperbaric Oxygen Treatment for Central Retinal Artery Occlusion: A Single Center Experience.

PURPOSE: To describe the outcomes of hyperbaric oxygen therapy (HBOT) for patients with central retinal artery occlusion (CRAO) at a single tertiary care center. DESIGN: Retrospective clinical cohort study. METHODS: Medical records of all patients diagnosed with CRAO who received HBOT at Mayo Clinic in Rochester, Minnesota from 1/1/2009 to 12/31/2020 were reviewed to confirm diagnosis, time from onset to presentation, exam findings, treatments, and follow-up data. Main outcome measures included final visual acuity (VA) and number of lines of improvement. RESULTS: There were 41 patients diagnosed with CRAO who received HBOT during the 12 year study period. Median time from symptom onset to HBOT treatment was 9.5 hours (interquartile range [IQR] 6.5, 14.0 hours), and patients received a median of 4 HBOT sessions (IQR 2.5, 6.0 sessions). There were 20 patients who received HBOT within 9 hours, 14 (70%) of which had clinically meaningful improvement in VA of ≥0.3 logMAR. In comparison, of the 21 patients treated after 9 hours, 6 (28.6%) had VA improvement of ≥0.3 logMAR (p=0.008). For all patients, the median logMAR VA at presentation was 2.00 (IQR 1.70, 2.30) and the median logMAR VA at follow-up was 1.94 (IQR 1.00, 2.00) (p<0.001), with median lines of improvement of 3.0 (IQR 0.0, 7.0). For patients treated within 9 hours, the median logMAR VA at presentation was 2.00 (IQR 1.93, 2.30) and the median logMAR VA at follow-up was 1.70 (IQR 0.54, 2.00). Patients treated within 9 hours had statistically significant greater median lines of VA improvement than cases that were treated after >9 hours from symptom onset at 5.9 (IQR 3.0, 10.0) and 0.0 (IQR 0.0, 3.0), respectively (p<0.001). There was no difference in VA recovery associated with specific retinal exam findings such as cherry-red spot (p=0.22) and cilioretinal artery perfusion (p=0.36) compared to patients without those findings. CONCLUSION: There was a statistically significant improvement in VA after HBOT treatment in CRAO patients among patients that received early HBOT, with patients receiving the most benefit when receiving treatment within 9 hours. Randomized control trials in patients with CRAO are required to confirm the efficacy of HBOT.

Limb Salvage in Extensive Necrotizing Soft Tissue Infection with Adjuvant Hyperbaric Oxygen Therapy.

A necrotizing soft tissue infection (NSTI) can be life-threatening if not treated promptly, posing a high risk of limb amputation. Here, we report a case of an NSTI extending from the buttocks and perineum down to the left lower limb. The case involved a 48-year-old male patient who presented with fever, altered consciousness, and limb swelling. Computed tomography showed the infection had spread to the perifascial, intermuscular, and intramuscular regions, making it difficult to save the patient's life and limb. Despite prompt surgery and antibiotic treatment, multidrug-resistant bacteria presented difficult wound management challenges. Hyperbaric oxygen therapy (HBO) was initiated, which resulted in dramatic wound improvement and successful skin grafting. Due to limb preservation, the patient was able to recover his preadmission activities of daily living and successfully reintegrate into society. Standard treatments for NSTI include early surgical treatment, antibiotics, and intensive support. The adjunctive use of HBO therapy may have contributed to the successful outcome in this case.

The Effectiveness of Hyperbaric Oxygen Treatment in Patients with Complex Regional Pain Syndrome: A Retrospective Case series.

Background: Complex regional pain syndrome (CRPS) presents as persistent regional pain, both spontaneous and triggered. The demand persists for innovative treatments that patients can endure with minimal adverse effects. Hyperbaric oxygen therapy (HBOT) emerges as a possible intervention in this regard. Methods: The main objective of this work is to retrospectively analyse a case series of patients diagnosed with CRPS treated in the Centre of Hyperbaric Medicine Ostrava over two years (period 2018-2019). The HBOT was applied at 2.0-2.4 absolute atmosphere (ATA) once a day. Results: A total of 83 patients with CRPS were treated with HBOT. 98% of cases reported pain, 92% reported limitation of movement of the affected limb, 87% had swelling of the limb, 41% had lividity and 70% had sensory problems. The mean number of HBOT exposures was 22.0 ± 7.1. At the end of HBOT treatment, 86% of cases had symptoms relief. The mean VAS value of pain at rest before the start of HBOT was 3.2±3.0, after treatment it was 1.6±1.9 (p<0.001). In a pain at activity it was 6.1±2.4 and 3.7±2.4 (p<0.001), respectively, at the end of HBOT. The value of the functional assessment of the limb was 7.0±2.0 and 4.3±2.4 (p<0.001), respectively, at the end of treatment. 79 cases were included in the end-of-treatment assessment. 23 cases (29%) were evaluated as large clinically significant response, 48 cases (61%) were evaluated as partial response with minimally important difference. The results showed larger clinical HBOT effect in cases of disease duration up to 3 and 6 months (p=0.029). Conclusions: The majority of patients improved pain and functional state of the affected limb. Our data also suggests the sooner after diagnosis of CRPS is HBOT started, the treatment has larger clinical effect. There was no serious HBOT-related complication or injury.

ROS exhaustion reverses the effects of hyperbaric oxygen on hemorrhagic transformation through reactivating microglia in post-stroke hyperglycemic mice.

Acute ischemic stroke (AIS) is a major global health concern due to its high mortality and disability rates. Hemorrhagic transformation, a common complication of AIS, leads to poor prognosis yet lacks effective treatments. Preclinical studies indicate that hyperbaric oxygen (HBO) treatment within 12 h of AIS onset alleviates ischemia/reperfusion injuries, including hemorrhagic transformation. However, clinical trials have yielded conflicting results, suggesting some underlying mechanisms remain unclear. In this study, we confirmed that HBO treatments beginning within 1 h post reperfusion significantly alleviated the haemorrhage and neurological deficits in hyperglycemic transient middle cerebral arterial occlusion (tMCAO) mice, partly due to the inhibition of the NLRP3 inflammasome-mediated pro-inflammatory response in microglia. Notably, reactive oxygen species (ROS) mediate the anti-inflammatory and protective effect of early HBO treatment, as edaravone and N-Acetyl-L-Cysteine (NAC), two commonly used antioxidants, reversed the suppressive effect of HBO treatment on NLRP3 inflammasome-mediated inflammation in microglia. Furthermore, NAC countered the protective effect of early HBO treatment in tMCAO mice with hyperglycemia. These findings support that early HBO treatment is a promising intervention for AIS, however, caution is warranted when combining antioxidants with HBO treatment. Further assessments are needed to clarify the role of antioxidants in HBO therapy for AIS.

The Impact of Poststroke Aphasia on Quality of Life: A Comparative Cross-Sectional Study.

OBJECTIVES: The study aimed to analyze the impact of aphasia on quality of life (QoL) in persons with ischemic stroke per radiological severity, compare equally severe but nonaphasic stroke survivors, and analyze the impact of hyperbaric oxygen therapy (HBOT) exposure. Methods: Patients with first-ever middle cerebral artery (MCA) stroke were categorized by radiological severity into high, intermediate, and low Alberta Stroke Program Early CT Score (ASPECTS). The Stroke Aphasia Quality of Life (SAQoL) Scale was used for outcome analysis. Inclusion criteria were age 40-65, 12-16 months after stroke, MCA distribution, first stroke, and ischemic stroke. Exclusion criteria were mixed vessel involvement and concomitant neurological, orthopedic, or psychiatric comorbidities. RESULTS: Among 93 patients with ischemic stroke, 87% presented with intermediate-to-low ASPECTS. According to the SAQoL, locomotion and transfers were the most compromised. QoL was significantly negatively correlated with higher ASPECTS and greater stroke impact in those with aphasia overall (p = 0.001). Those who received HBOT overall were significantly better than those who did not, regardless of group (p = 0.02 and 0.03). CONCLUSION: The present study shows that the radiological severity of stroke relates to QoL in those with poststroke aphasia. Among those with equal radiological severity, those with aphasia are worse off. Those who receive HBOT have better QoL.

Effects of hyperbaric oxygen pre-exposure on the motor learning acquisition phase.

Hyperbaric oxygen (HBO) exposure has recently been reported to be effective in spatial learning and memory. Additionally, HBO exposure considerably improves performance on motor tasks. These findings suggest that HBO exposure may facilitate motor learning. However, the specific effects of HBO exposure on motor learning remain largely unexplored. The present study aimed to investigate the effects of HBO exposure on motor learning tasks. In the experimental animal models (control n = 8, HBO n = 8), the HBO environment was exposed to 100 % oxygen with the chamber at 2.0 atmosphere absolute (ATA) for 90 min/day for 20 days. The motor learning task was an accelerated rotating bar task (bar width, 3 and 6 cm; rotation speed, 4-40 rpm; acceleration, 0.4, 0.6, and 0.8 rpm/s). The learning task was performed for 3 consecutive days. The HBO group showed a main effect of the day factor on the bar with a width of 6 cm, and significant differences were observed for each day comparison. However, no main effect of the day factor was observed in the control group. Additionally, significant differences were found in the bar with a width of 3 cm for both groups between days 1 and 2 and between days 1 and 3. In conclusion, these findings suggest that HBO exposure has a positive effect on more challenging motor learning tasks.

Radiation effects in head and neck and role of hyperbaric oxygen therapy: An adjunct to management.

Background: Radiotherapy is considered an essential treatment modality in cancers, especially head and neck cancers. Radiotherapy can be given as a definitive, supportive, or adjuvant therapy for various cancers. Radiation damage is an avoidable complication in many patients, after or during radiotherapy. It may be either dose-related, duration-related, or frequency-related. The effects of radiation damage are mainly caused by ischemic necrosis, and once settled it is difficult to manage due to the low vascularity of the affected area. Aim: To find out the effectiveness of hyperbaric oxygen therapy (HBOT) in the management of radiation damage in the head and neck region. Materials and Methods: Retrospective data of patients attending the HBOT clinic for postradiotherapy changes were recorded in an Excel sheet and analyzed in this study. Statistical analysis was done. Result: Our study showed that HBOT is effective in postradiation trismus, xerostomia, discharge, foul smell, discharging sinus, etc., However, it was not found to be significant in the closure of fistula with exposed bone. Conclusion: HBOT is an effective adjunct modality for the management of postradiation changes in the head and neck region.

Oxidative hemolytic crises in a dog due to fragrance products: clinical insights and treatment approaches.

IMPORTANCE: This is the first reported case of fragrance products-induced recurrent oxidative hemolytic anemia in a dog, detailing the successful therapeutic approach employed. CASE PRESENTATION: A 4-year-old intact female Pomeranian dog presented with brown tongue, pigmenturia, peripheral edema, and vomiting. Blood smears revealed a high count of eccentrocytes and Heinz bodies, along with a precipitous decline in packed cell volume and an increase in blood methemoglobin levels, suggesting an oxidative hemolytic crisis. This clinicopathological pattern recurred several times after the patient returned home. Antioxidants, methylene blue, hyperbaric oxygen (HBO) therapy, and blood transfusion were successfully employed to address recurrent hemolytic anemia; however, oxidative hemolytic crises recurred. After the owner removed exposure to various home remedies and fragrances, the clinical signs and hemolytic crises did not recur. CONCLUSIONS AND RELEVANCE: Recurring oxidative hemolytic crises should raise suspicions of environmental toxicity, which, although harmless in small quantities to humans, can be devastating to small-breed dogs. In addition to removing the causative agents, methylene blue and other antioxidants, along with HBO, may be beneficial in the acute management of oxidative hemolytic anemia.

Hyperbaric intervention ameliorates the negative effects of long-term high-altitude exposure on cognitive control capacity.

Introduction: Hypoxia due to reduced partial pressure of oxygen from high-altitude exposure affects the cognitive function of high-altitude migrants. Executive function is an important component of human cognitive function, characterized by high oxygen consumption during activity, and its level can be measured using cognitive control capacity (CCC). In addition, there is evidence for the potential value of hyperbaric oxygen (HBO) interventions in improving cognitive decline on the plateau. Therefore, the objective of this study was to investigate the effect of long-term high-altitude exposure on CCC in high-altitude newcomers and whether hyperbaric oxygen intervention has an ameliorative effect. Methods: This study measured the magnitude of participants' CCC using a Backward Masking Majority Function Task (MFT-M). Study 1 was a controlled study of different altitude conditions, with 64 participants in the high-altitude newcomer group and 64 participants in the low-altitude resident group, each completing the MFT-M task once. Study 2 was a controlled HBO intervention study in which newcomers who had lived at a high altitude for 2 years were randomly divided into the HBO group (n = 28) and control group (n = 28). 15 times hyperbaric oxygen interventions were performed in the HBO group. Subjects in both groups completed the MFT-M task once before and once after the intervention. Results: Study 1 showed that CCC was significantly higher in the low-altitude resident group than in the high-altitude newcomer group (p = 0.031). Study 2 showed that the CCC in the HBO group was significantly higher after 15 hyperbaric interventions than before (p = 0.005), while there was no significant difference in the control group (p = 0.972). The HBO group had significantly higher correct task rates than the control group after the intervention (p = 0.001). Conclusion: This study confirms that long-term high-altitude exposure leads to impairment of CCC in high-altitude newcomers and that hyperbaric oxygen intervention is effective in improving CCC.

Effects of Hyperbaric Oxygen Therapy for Malignant Bowel Obstruction Caused by Peritoneal Dissemination.

INTRODUCTION: This study aimed to investigate the efficacy of hyperbaric oxygen therapy (HBOT) in patients presenting with malignant bowel obstruction (MBO) and peritoneal dissemination. MATERIALS AND METHODS: We retrospectively examined whether HBOT affects prognosis following MBO with peritoneal dissemination. This study included 44 patients diagnosed with MBO secondary to peritoneal dissemination at our hospital between January 2013 and December 2022. Among these patients, 30 underwent HBOT. The treatment protocol involved daily HBOT administration, comprising 100% oxygen at 2.5 atmospheres absolute for 60 min. RESULTS: In a univariate analysis of HBOT and non-HBOT groups, the proportion of patients able to resume eating was significantly higher in the HBOT group. Therefore, the percentage of patients in the non-HBOT group whose MBO did not improve was significantly higher than that in the HBOT group. The percentage of patients undergoing surgery or receiving anticancer treatment did not differ significantly between the groups, whereas overall survival was significantly longer in the HBOT group. Furthermore, when examining inoperable patients, significantly more individuals in the HBOT group could resume eating, and their overall survival was significantly prolonged. CONCLUSIONS: HBOT may increase the spontaneous resolution rate and improve long-term prognoses of patients with MBO secondary to peritoneal dissemination.

Successful management of renal abscess secondary to diabetes mellitus with surgical treatment and hyperbaric oxygen therapy.

Renal abscess (RA) is a collection of infective fluid in or around the renal parenchyma. It typically occurs in immunocompromised patients, including those with diabetes mellitus (DM), poor nutritional status, or steroid administration. We herein report a case of RA associated with DM in which hyperbaric oxygen (HBO2) therapy greatly contributed to the resolution of this disease. The patient was an 85-year-old man with poorly controlled type 2 DM. Contrast-enhanced computed tomography for postoperative follow-up of appendiceal cancer showed a mass lesion with poor contrast enhancement extending from the upper pole of the left kidney to the dorsal side. Therefore, a diagnosis of RA was established. The lesion was percutaneously punctured, and a drainage tube was placed. Antibiotics following sensitivity testing were administered. The catheter was removed six days after its placement. However, pus discharge continued from the catheter removal site, with persistent redness around the wound. Therefore, a lumbotomy incision for abscess drainage was performed on the 49th day. However, the pus discharge persisted, and we decided to perform HBO2 therapy, expecting decreases in bacterial proliferation, reduction in local edema, and improvement of host defense. HBO2 therapy for 90 min at two atmospheres absolute was performed ten times. The amount of pus discharge decreased, and redness improved from the fifth day after HBO2 therapy. One month after starting HBO2 therapy, the wound was closed, and the pus discharge resolved completely. Four years have passed since the HBO2 therapy, and there have been no symptomatic or imaging relapses of RA.

Hyperbaric oxygen therapy for avascular necrosis of the femoral head: A case report.

The hip is the most common location for avascular necrosis of the femoral head (AVN), with an estimated incidence in the United States of 10,000 to 20,000 new cases per year. The current standard of care for early disease is core decompression, with bone marrow injections becoming more commonplace. Hyperbaric oxygen enhances oxygen delivery to tissue, promotes an anti-inflammatory and pro-healing environment, and helps initiate angiogenesis. We believe that these properties of HBO2 make it a unique tool for AVN and applied it in conjunction with the standard of care for our patient.

Acoustic emission, an innovative diagnosis tool for therapeutic hyperbaric chambers: or how to requalify safely using pneumatic pressure test.

Therapeutic hyperbaric chambers require continuous monitoring and maintenance, including periodic requalification. The primary aim is to verify the suitability for continued safe service. Maintenance is regulated in Europe, and in France requalification is mandatory where a hyperbaric chamber operates above pressures equal to or greater than 4 bar gauge. French requalification requires a hydraulic (hydrostatic) pressure test to determine the absence of deformation and leaks during the test. However, in such cases, it is often necessary to move the chamber if the combined mass of the chamber and water may exceed the allowable floor loading strength. In 2009, an innovative alternative to a hydraulic pressure testing was authorised in France. It consists of carrying out a pneumatic pressure test simultaneously with a non-destructive monitoring technique called 'acoustic emission'. This can be compared to a microseismology technique, where sensors are applied to the pressure retaining boundary of the hyperbaric chamber, and signals emitted by the vessel under load are captured. These signals are analysed, prioritised, and classified, to determine the physical position of any sources (artifacts) through triangulation calculations. This technique makes it possible to assess the behaviour of the vessel very accurately in real time and, a posteriori, to assess its fitness for continued service. This technique reduces the unavailability time of the chamber to two days, compared to potentially several weeks when a hydraulic test is performed. Over and above financial considerations and availability of facilities, this technique provides a baseline of the integrity of pressure vessels and allows monitoring over time of any potential deterioration.

Methylphenidate and the risk of acute central nervous system oxygen toxicity: a rodent model and observational data in human divers.

Introduction: The effects of methylphenidate, a stimulant often prescribed for the treatment of attention-deficit/hyperactivity disorder (ADHD), on the development of central nervous system oxygen toxicity (COT) have not been experimentally evaluated. Methods: The records of all pure-oxygen-rebreather divers evaluated at our institution from 1975-2022 were assessed. Cases of COT were defined as a new onset of tinnitus, tunnel vision, myoclonus, headache, nausea, loss of consciousness, or seizures resolving within 15 minutes from breathing normobaric air, and matched 4:1 with similar controls. Any medications issued to the diver in the preceding three months, including methylphenidate, were recorded. In the animal arm of this study, male mice were exposed to increasing doses of methylphenidate orally, with subsequent exposure to hyperbaric O2 until clinically evident seizures were recorded. Results: Seventy-five cases of COT were identified in divers, occurring at a median of 80 (range 2-240) minutes after dive initiation at a median depth of 5 m (2-13). Hypercarbia was documented in 11 (14.7%) cases. Prescription of methylphenidate in the preceding three months was not associated with increased risk (OR 0.72, 95% CI 0.16-3.32) of COT. In mice, increasing methylphenidate exposure dose was associated with significantly longer mean COT latency time being 877 s (95% CI 711-1,043) with doses of 0 mg·kg⁻¹; 1,312 s (95% CI 850-1,773) when given 0.75 mg·kg⁻¹; and 1,500 s (95% CI 988-2,012) with 5 mg·kg⁻¹ (F = 4.635, P = 0.014). Conclusions: Observational human data did not demonstrate an association between methylphenidate and an increased risk of COT. Methylphenidate exposure in mice prolongs COT latency and may have protective effects against COT.

Hyperbaric Oxygen Therapy during Pregnancy for Critical Anemia Secondary to Sickle Cell Disease with Post-Transfusion Hyperhemolysis: A Case Report.

Background: Sickle cell disease is the most common human monogenetic disease, and its risks are amplified during pregnancy. Methods: This report describes a 35-year-old woman with HgbSS sickle cell disease who developed hyperhemolysis syndrome after undergoing an exchange transfusion during pregnancy. Results: In addition to conventional medical treatment, the patient received prepartum hyperbaric oxygen therapy (HBOT), totaling 17 treatments for the indication of severe anemia. She experienced significant clinical improvement while undergoing HBOT and ultimately delivered a healthy preterm infant by cesarean section. Conclusions: The risks, benefits, and challenges of using HBOT in this unique context are discussed.