Patient-Reported Outcome Measures Following Hyperbaric Oxygen Therapy for Radiation Cystitis: Early Results From the Multicenter Registry for Hyperbaric Oxygen Therapy.

PURPOSE: Our purpose was to determine changes in patient-reported hematuria and urinary symptoms after hyperbaric oxygen (HBO2) treatment for radiation cystitis (RC). MATERIALS AND METHODS: We analyzed prospectively collected data from the Multicenter Registry for Hyperbaric Oxygen Therapy Consortium accumulated within a week of beginning and ending HBO2. Measures included the modified Radiation Therapy Oncology Group (RTOG) Hematuria Scale, Urinary Distress Inventory Short Form, and EuroQol Five Dimension Five Level instrument. RTOG hematuria and Urinary Distress Inventory Short Form scores were compared using the sign test. Logistic regression was used to evaluate characteristics associated with hematuria improvement. RESULTS: A total of 470 registry patients had RC. The median age, number of HBO2 sessions, and years after radiation were 73 (IQR 12) years, 39 (IQR 10) sessions, and 5 (IQR 8) years, respectively. Eighty-four percent of patients (393/470) had prostate cancer‒related radiation. EuroQol Five Dimension Five Level scores improved from 0.83 (IQR 0.14) to 0.85 (IQR 0.22; P < .001. Three hundred seventy patients had complete RTOG hematuria scores that improved from 2 (IQR 2) to 0 (IQR 2; P < .001. Two hundred forty-six patients had complete Urinary Distress Inventory Short Form ratings that decreased from 33.3 (IQR 44) to 22.2 (IQR 33; P < .001). Regression analysis of those with visible hematuria before HBO2 showed lower improvement odds associated with higher HBO2 hematuria scores (odds ratio [OR] 0.44, 95% CI 0.26-0.73; P < .01), a smoking history (OR 0.44, 95% CI 0.21-0.92; P = .03), or a nonprostate cancer history (OR 0.32, 95% CI 0.10-0.99; P = .05). CONCLUSIONS: HBO2 for RC improved reported hematuria, urinary function, and quality of life. Higher baseline hematuria scores, smoking, and nonprostate cancer history were associated with lower odds of hematuria improvement.

Effects of Oxygen Therapy on Patients with a Chronic Wound: A Systematic Review and Meta-analysis.

OBJECTIVE: To synthesize the effects of oxygen-based therapy on patients with a chronic wound. DATA SOURCES: The authors searched PubMed, EMBASE, and Cochrane Central Register of Controlled Trials for relevant randomized controlled trials from database inception. Investigators measured risk of bias using the Cochrane Collaboration's Risk of Bias tool. STUDY SELECTION: The included randomized controlled trials focused on the effects (short- or long-term wound healing, amputation rate, percentage of reduction in ulcer size, and poststudy transcutaneous oxygen measurement [TcPO2]) of oxygen-based therapy (including hyperbaric oxygen therapy, topical oxygen therapy, and continuous diffusion of oxygen) on patients with a chronic wound. DATA EXTRACTION: Researchers extracted information regarding participant characteristics and primary and secondary outcomes from the included studies. DATA SYNTHESIS: Pooled effects of 31 included studies showed that patients treated with oxygen had better short-term wound healing (risk ratio [RR], 1.544; 95% CI, 1.199 to 1.987), a higher percentage reduction in the ulcer area (standardized mean difference [SMD], 0.999; 95% CI, 0.439 to 1. 599), lower amputation rates (RR, 0.529; 95% CI, 0.325 to 0.862), shorter wound healing time (SMD, -0.705; 95% CI, -0.908 to -0.501), and higher poststudy TcPO2 (SMD, 2.128; 95% CI, 0.978 to 3.278) than those in the control group. For long-term wound healing, there was no statistically significant difference (RR, 1.227; 95% CI, 0.976 to 1.542). CONCLUSIONS: Oxygen-based therapy improves short-term parameters of wound healing in patients with chronic wounds.

Hyperbaric Oxygen Reduces Oxidative Stress Impairment and DNA Damage and Simultaneously Increases HIF-1α in Ischemia-Reperfusion Acute Kidney Injury.

The central exacerbating factor in the pathophysiology of ischemic-reperfusion acute kidney injury (AKI) is oxidative stress. Lipid peroxidation and DNA damage in ischemia are accompanied by the formation of 3-nitrotyrosine, a biomarker for oxidative damage. DNA double-strand breaks (DSBs) may also be a result of postischemic AKI. γH2AX(S139) histone has been identified as a potentially useful biomarker of DNA DSBs. On the other hand, hypoxia-inducible factor (HIF) is the "master switch" for hypoxic adaptation in cells and tissues. The aim of this research was to evaluate the influence of hyperbaric oxygen (HBO) preconditioning on antioxidant capacity estimated by FRAP (ferric reducing antioxidant power) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay, as well as on oxidative stress parameter 3-nitrotyrosine, and to assess its effects on γH2AX(S139), HIF-1α, and nuclear factor-κB (NF-κB) expression, in an experimental model of postischemic AKI induced in spontaneously hypertensive rats. The animals were divided randomly into three experimental groups: sham-operated rats (SHAM, n = 6), rats with induced postischemic AKI (AKI, n = 6), and group exposed to HBO preconditioning before AKI induction (AKI + HBO, n = 6). A significant improvement in the estimated glomerular filtration rate, eGFR, in AKI + HBO group (p < 0.05 vs. AKI group) was accompanied with a significant increase in plasma antioxidant capacity estimated by FRAP (p < 0.05 vs. SHAM group) and a reduced immunohistochemical expression of 3-nitrotyrosine and γH2AX(S139). Also, HBO pretreatment significantly increased HIF-1α expression (p < 0.001 vs. AKI group), estimated by Western blot and immunohistochemical analysis in kidney tissue, and decreased immunohistochemical NF-κB renal expression (p < 0.01). Taking all of these results together, we may conclude that HBO preconditioning has beneficial effects on acute kidney injury induced in spontaneously hypertensive rats.

Hyperbaric oxygen therapy promotes the browning of white fat and contributes to the healing of diabetic wounds.

Non-healing wounds are one of the chronic complications of diabetes and have remained a worldwide challenge as one of the major health problems. Hyperbaric oxygen (HBO) therapy is proven to be very successful for diabetic wound treatment, for which the molecular basis is not understood. Adipocytes regulate multiple aspects of repair and may be therapeutic for inflammatory diseases and defective wound healing associated with aging and diabetes. Endothelial cell-derived extracellular vesicles could promote wound healing in diabetes. To study the mechanism by which HBO promotes wound healing in diabetes, we investigated the effect of HBO on fat cells in diabetic mice. A diabetic wound mouse model was established and treated with HBO. Haematoxylin and eosin (H&E) staining and immunofluorescence were used for the analysis of wound healing. To further explore the mechanism, we performed whole-genome sequencing on extracellular vesicles (EVs). Furthermore, we conducted in vitro experiments. Specifically, exosomes were collected from human umbilical vein endothelial cell (HUVEC) cells after HBO treatment, and then these exosomes were co-incubated with adipose tissue. The wound healing rate in diabetic mice treated with HBO was significantly higher. HBO therapy promotes the proliferation of adipose precursor cells. HUVEC-derived exosomes treated with HBO significantly promoted fat cell browning. These data clarify that HBO therapy may promote vascular endothelial cell proliferation and migration, and promote browning of fat cells through vascular endothelial cells derived exosomes, thereby promoting diabetic wound healing. This provides new ideas for the application of HBO therapy in the treatment of diabetic trauma.

Transcutaneous oximetry values in chronic ulcer patients during Hyperbaric treatment at 1.4 ATA compared to 2 ATA.

Chronic wounds have a significant impact on a patient's quality of life. Different pathologies, such as poor blood supply and tissue breakdown, may lead to inadequate oxygenation of the wound. Hyperbaric oxygen (HBO2) is a widely used treatment for an increasing number of medical practices. A new so-called "hyperbaric treatment" trend has emerged. The use of low-pressure, soft-sided, or inflatable chambers represents a growing trend in hyperbaric medicine. Used in professional settings as well as directly marketed to individuals for home use, they are promoted as equivalent to clinical hyperbaric treatments provided in medical centers. However, these chambers are pressurized to 1.3 atmospheres absolute (ATA) on either air or with an oxygen concentrator, both generate oxygen partial pressures well below those used in approved hyperbaric centers for UHMS-approved indications. A total of 130 consecutive patients with chronic ulcers where tested. TcPO2 was measured near the ulcer area while the patient was breathing 100% O2 at 1.4 ATA for five and 10 minutes. The average TcPO2 at 1.4 ATA after 10 minutes of O2 breathing was 161 mmHg (1-601 mmHg, standard deviation 137.91), compared to 333 mmHg in 2 ATA (1-914±232.56), p < 0.001. Each electrode tested was also statistically significant, both after five minutes of O2 breathing and after 10 minutes. We have not found evidence supporting the claim that 1.4 ATA treatment can benefit a chronic ulcer patient. The field of HBO2 is constantly evolving. We have discovered new ways to treat previously incurable ailments. Nevertheless, it is important to note that new horizons must be examined scientifically, supported by evidence-based data. The actual effect of 1.4 ATA on many ailments is yet to be determined.

Surviving cardiac arrest after carbon monoxide poisoning treated with hyperbaric oxygen therapy.

Carbon monoxide (CO) and cyanide poisoning are frequent causes of morbidity and mortality in cases of house and industrial fires. The 14th edition of guidelines from the Undersea and Hyperbaric Medical Society does not recommend hyperbaric oxygen (HBO2) treatment in those patients who have suffered a cardiac arrest and had to receive cardiopulmonary resuscitation. In this paper, we describe the case of a 31-year-old patient who received HBO2 treatment in the setting of cardiac arrest and survived.

Barodontalgia during hyperbaric oxygen therapy of an 8-year-old male: A case report.

Barodontalgia, barometric pressure-induced dental pain, may occur during hyperbaric oxygen(HBO2) therapy due to pressure changes. This case report presents an 8-year-old male patient with barodontalgia. The patient declared a severe toothache during HBO2 therapy. The diving medicine specialist referred the patient to the dental clinician immediately. On clinical examination, the pain was thought to be caused by caries lesions of the deciduous teeth in the left maxillary molar region. Tooth extraction was suggested. After extraction, the patient continued hyperbaric oxygen therapy sessions without any pain. The patient was recommended for an intraoral and radiographic examination session one week after the extraction. In conclusion, caries lesions and faulty restorations should be examined before hyperbaric oxygen therapy sessions. Even though barodontalgia is a rare phenomenon, dental examination is essential to avoid these kinds of pain-related complications. All carious lesions and defective restorations must be treated, if necessary. Removal of faulty restorations and management of inflammation as part of the treatment is suggested before exposure to pressure changes.

Chondronecrosis of the cricoid treated with hyperbaric oxygen therapy: A case series.

We present two cases of cricoid chondronecrosis treated with hyperbaric oxygen (HBO2) therapy. Both patients presented with biphasic stridor and dyspnea several weeks after an intubation event. Tracheostomy was ultimately performed for airway protection, followed by antibiotic treatment and outpatient HBO2 therapy. Both patients were decannulated within six months of presentation and after at least 20 HBO2 therapy sessions. Despite a small sample size, our findings are consistent with data supporting HBO2 therapy's effects on tissue edema, neovascularization, and HBO2 potentiation of antibiotic treatment and leukocyte function. We suggest HBO2 therapy may have accelerated airway decannulation by way of infection resolution as well as the revitalization of upper airway tissues, ultimately renewing the structural integrity of the larynx. When presented with this rare but significant clinical challenge, physicians should be aware of the potential benefits of HBO2 therapy.

Pneumothorax during manned chamber operations: A summary of reported cases.

In-chamber pneumothorax has complicated medically remote professional diving operations, submarine escape training, management of decompression illness, and hospital-based provision of hyperbaric oxygen therapy. Attempts to avoid thoracotomy by combination of high oxygen partial pressure breathing (the concept of inherent unsaturation) and greatly slowed rates of chamber decompression proved successful on several occasions. When this delicate balance designed to prevent the intrapleural gas volume from expanding faster than it contracts proved futile, chest drains were inserted. The presence of pneumothorax was misdiagnosed or missed altogether with disturbing frequency, resulting in wide-ranging clinical consequences. One patient succumbed before the chamber had been fully decompressed. Another was able to ambulate unaided from the chamber before being diagnosed and managed conventionally. In between these two extremes, patients experienced varying degrees of clinical compromise, from respiratory distress to cardiopulmonary arrest, with successful resuscitation. Pneumothorax associated with manned chamber operations is commonly considered to develop while the patient is under pressure and manifests during ascent. However, published reports suggest that many were pre-existing prior to chamber entry. Risk factors included pulmonary barotrauma-induced cerebral arterial gas embolism, cardiopulmonary resuscitation, and medical or surgical procedures usually involving the lung. This latter category is of heightened importance to hyperbaric operations as an iatrogenically induced pneumothorax may take as long as 24 hours to be detected, perhaps long after a patient has been cleared for chamber exposure.

Outcomes after pancreaticoduodenectomy with or without preoperative hyperbaric oxygen therapy.

Background: Hyperbaric oxygen (HBO2) therapy is an alternative method against the deleterious effects of ischemic/reperfusion (I/R) injury and its inflammatory response. This study assessed the effect of preoperative HBO2 on patients undergoing pancreaticoduodenectomy. Study Design: Patients were randomized via a computer-generated algorithm. Patients in the HBO2 cohort received two sessions of HBO2 the evening before and the morning of surgery. Measurements of inflammatory mediators and self-assessed pain scales were determined pre-and postoperatively. In addition, perioperative variables and long-term survival were collected and analyzed. Data are presented as median (mean ± SD). Results: 33 patients were included; 17 received preoperative HBO2, and 16 did not. There were no intraoperative or postoperative statistical differences between patients with or without preoperative HBO2. Erythrocyte sedimentation rate (ESR), IL-6, and IL-10 increased slightly before returning to normal, while TGF-alpha decreased before increasing. However, there were no differences with or without HBO2. At postoperative day 30, the pain level measured with VAS score (Visual Analog Score) was lower after HBO2 (1 ± 1.3 vs. 3 ± 3.0, p=0.05). Eleven (76%) patients in the HBO2 cohort and 12 (75%) patients in the non- HBO2 had malignant pathology. The percentage of positive lymph nodes in the HBO2 was 7% compared to 14% in the non-HBO2 (p<0.001). Overall survival was inferior after HBO2 compared to the non- HBO2 (p=0.03). Conclusions: Preoperative HBO2 did not affect perioperative outcomes or significantly change the inflammatory mediators for patients undergoing robotic pancreaticoduodenectomy. Long-term survival was inferior after preoperative HBO2. Further randomized controlled studies are required to assess the full impact of this treatment on patients' prognosis.

Effect of hyperbaric oxygen in hepatopulmonary syndrome: an innovative experimental study.

OBJECTIVE: This study aimed to analyze the effect of hyperbaric oxygen treatment (HBOT) in hepatopulmonary syndrome (HPS). MATERIALS AND METHODS: Five-month-old female Wistar-Albino rats were randomly divided into three groups: Group I, the control group; Group II, the cirrhosis group; and Group III, the cirrhosis group + HBOT group. Rats were exposed to HBO sessions (2.4 atm./60 min) for 20 days. Animals were sacrificed 24 hours after the last HBO session. Biochemical analysis, oxygenation parameters, NO and NO synthase (NOS) levels, histopathological changes in the liver and lungs, and pulmonary artery diameter were measured. RESULTS: A total of 24 rats (10 rats were included in Group I, six rats in Group II, and eight rats in Group III) weighing 220-250 g were included in the study. Significant differences were observed for NO and NOS (9.10±1.05 to 12.17±1.85 µmol/L, p<0.05 and 0.46±0.31 to 1.17±0.39 U/ml, p<0.05, respectively) at baseline and day 36 only in group II. Inflammatory cell infiltration and bronchial injury were significantly increased in group II compared to group I (p=0.007 and p=0.008, respectively) but not in group III (p=0.266 and p=0.275, respectively). Pulmonary artery diameter was significantly lower in group III compared with group II at all sites in both lungs (p<0.05). CONCLUSIONS: HBOT may be a promising treatment for HPS by reducing NO and NOS activity, perialveolar arteriolar dilation, lung inflammation, and injury and guiding future clinical trials.

Oxidative Stress Reaction to Hypobaric-Hyperoxic Civilian Flight Conditions.

BACKGROUND: In military flight operations, during flights, fighter pilots constantly work under hyperoxic breathing conditions with supplemental oxygen in varying hypobaric environments. These conditions are suspected to cause oxidative stress to neuronal organ tissues. For civilian flight operations, the Federal Aviation Administration (FAA) also recommends supplemental oxygen for flying under hypobaric conditions equivalent to higher than 3048 m altitude, and has made it mandatory for conditions equivalent to more than 3657 m altitude. AIM: We hypothesized that hypobaric-hyperoxic civilian commercial and private flight conditions with supplemental oxygen in a flight simulation in a hypobaric chamber at 2500 m and 4500 m equivalent altitude would cause significant oxidative stress in healthy individuals. METHODS: Twelve healthy, COVID-19-vaccinated (third portion of vaccination 15 months before study onset) subjects (six male, six female, mean age 35.7 years) from a larger cohort were selected to perform a 3 h flight simulation in a hypobaric chamber with increasing supplemental oxygen levels (35%, 50%, 60%, and 100% fraction of inspired oxygen, FiO2, via venturi valve-equipped face mask), switching back and forth between simulated altitudes of 2500 m and 4500 m. Arterial blood pressure and oxygen saturation were constantly measured via radial catheter and blood samples for blood gases taken from the catheter at each altitude and oxygen level. Additional blood samples from the arterial catheter at baseline and 60% oxygen at both altitudes were centrifuged inside the chamber and the serum was frozen instantly at -21 °C for later analysis of the oxidative stress markers malondialdehyde low-density lipoprotein (M-LDL) and glutathione-peroxidase 1 (GPX1) via the ELISA test. RESULTS: Eleven subjects finished the study without adverse events. Whereas the partial pressure of oxygen (PO2) levels increased in the mean with increasing oxygen levels from baseline 96.2 mm mercury (mmHg) to 160.9 mmHg at 2500 m altitude and 60% FiO2 and 113.2 mmHg at 4500 m altitude and 60% FiO2, there was no significant increase in both oxidative markers from baseline to 60% FiO2 at these simulated altitudes. Some individuals had a slight increase, whereas some showed no increase at all or even a slight decrease. A moderate correlation (Pearson correlation coefficient 0.55) existed between subject age and glutathione peroxidase levels at 60% FiO2 at 4500 m altitude. CONCLUSION: Supplemental oxygen of 60% FiO2 in a flight simulation, compared to flying in cabin pressure levels equivalent to 2500 m-4500 m altitude, does not lead to a significant increase or decrease in the oxidative stress markers M-LDL and GPX1 in the serum of arterial blood.

Clinical features and predictors of delayed neurological syndrome in carbon monoxide poisoning: the AMICO study. / Caracterización clínica y factores predictivos de desarrollo de síndrome neurológico tardío en la intoxicación por monóxido de carbono: estudio AMICO.

OBJECTIVES: To identify predictors for developing delayed neurological syndrome (DNS) after an initial episode of carbon monoxide (CO) poisoning in the interest of detecting patients most likely to develop DNS so that they can be followed. MATERIAL AND METHODS: Retrospective review of cases of CO poisoning treated in the past 10 years in the emergency departments of 4 hospitals in the AMICO study (Spanish acronym for the multicenter analysis of CO poisoning). We analyzed demographic characteristics of the patients and the clinical characteristics of the initial episode. The records of the cohort of patients with available follow-up information were reviewed to find cases of DNS. Data were analyzed by multivariant analysis to determine the relationship to characteristics of the initial exposure to CO. RESULTS: A total of 240 cases were identified. The median (interquartile range) age of the patients was 36.2 years (17.6-49.6 years); 108 patients (45.0%) were men, and the poisoning was accidental in 223 cases (92.9%). The median carboxyhemoglobin concentration on presentation was 12.7% (6.2%-18.7%). Follow-up details were available for 44 patients (18.3%). Eleven of those patients (25%) developed DNS. A low initial Glasgow Coma Scale score predicted the development of DNS with an odds ratio (OR) of 0.61 (95% CI, 0.41-0.92) and an area under the receiver operating characteristic curve of 0.876 (95% CI, 0.761-0.990) (P .001). CONCLUSION: The initial Glasgow Coma Scale score seems to be a clinical predictor of DNS after CO poisoning. We consider it important to establish follow-up protocols for patients with CO poisoning treated in hospital EDs.

OBJETIVO: Identificar factores pronósticos de desarrollo de síndrome neurológico tardío (SNT) después de un episodio inicial de intoxicación por monóxido de carbono (ICO), con el fin detectar precozmente a la población más susceptible y facilitar su acceso a un seguimiento específico. METODO: Revisión retrospectiva de todos los casos de ICO que acudieron a los servicios de urgencias (SU) de 4 hospitales durante los últimos 10 años. Se analizaron datos demográficos y características clínicas en el momento del episodio. En la cohorte de pacientes con datos de seguimiento disponibles, se evaluó la aparición de SNT y su relación con diferentes variables en la exposición inicial al CO a través de técnicas de análisis multivariante. RESULTADOS: Se identificaron 240 pacientes. La mediana de edad fue de 36,2 años (17,6-49,6). De ellos 108 (45,0%) eran hombres y 223 casos (92,9%) fueron accidentales. El nivel medio de COHb fue del 12,7% (6,2-18,7). En 44 (18,3%) episodios se disponía de datos de un seguimiento específico. En esta cohorte, 11 (25%) pacientes desarrollaron SNT. Una puntuación inicial más baja en la Escala Coma de Glasgow (GCS) (OR: 0,61, IC 95%: 0,41-0,92) fue predictor independiente del desarrollo del SNT, con un ABC en la curva COR de 0,876 (IC 95%: 0,761-0,990, p 0,001). CONCLUSIONES: Una puntuación inicial baja en la GCS parece ser un predictor clínico de desarrollo de SNT en la ICO. Dada la incidencia de SNT, consideramos fundamental establecer protocolos de seguimiento específico de estos pacientes tras su asistencia inicial en los SU.

Oxygen Straight to the Brain: An Overview of Hyperbaric Oxygen Therapy for a Variety of Brain Morbidities.

ABSTRACT: Hyperbaric oxygen therapy as a treatment for conditions like traumatic brain injury, posttraumatic stress disorder, and migraines would seem intuitive, given its effect on condition-related ischemia and inflammation. However, hyperbaric therapeutic impacts for these in acute and chronic, or prolonged symptoms are elusive. This narrative review of hyperbaric's utility provided in sections per disease renders first a review of conventional pathological mechanisms and then articulates hyperbaric treatment targets versus their respective impacts. Multiple challenges exist using hyperbaric oxygen therapy for each morbidity, even in tertiary and adjunctive treatments. An almost universal shortfall across studies includes a lack of consistent, appropriate patient selection criteria intersected with delivery timing of therapy to symptomatic target, necessary to provide a higher fidelity in treatment metrics. Further research into these respective conditions is needed along with a revisitation of hyperbaric oxygen therapy's application to their conventional pathological mechanisms, lending new perspective to their employment and efficacy.

Hyperbaric oxygen treatment for infants: retrospective analysis of 54 patients treated in two tertiary care centres.

Introduction: We aimed to analyse the outcomes of hyperbaric oxygen treatment (HBOT) and describe difficulties encountered in infants, a rare patient population in this therapeutic intervention, with limited scientific reports. Methods: This was a retrospective analysis of patients 12 months old or younger who underwent HBOT in two different institutions. Demographic data, clinical presentation, HBOT indication, chamber type, oxygen delivery method, total number of treatments, outcome and complications were extracted from clinical records. Results: There were 54 infants in our study. The patients' median age was 3.5 (range 0-12) months. The major HBOT indication was acute carbon monoxide intoxication (n = 32). A total of 275 HBOT treatments were administered, mostly performed in multiplace chambers (n = 196, 71%). Only one patient (2%) required mechanical ventilation. Acute signs were fully resolved in the most patients (n = 40, 74%). No complications related to HBOT were reported. Conclusions: This study suggests that HBOT may be a safe and effective treatment for infants. Paediatricians should consider HBOT when indicated in infants even for the preterm age group.

Efficacy of searching in biomedical databases beyond MEDLINE in identifying randomised controlled trials on hyperbaric oxygen treatment.

Introduction: Literature searches are routinely used by researchers for conducting systematic reviews as well as by healthcare providers, and sometimes patients, to quickly guide their clinical decisions. Using more than one database is generally recommended but may not always be necessary for some fields. This study aimed to determine the added value of searching additional databases beyond MEDLINE when conducting a literature search of hyperbaric oxygen treatment (HBOT) randomised controlled trials (RCTs). Methods: This study consisted of two phases: a scoping review of all RCTs in the field of HBOT, followed by a a statistical analysis of sensitivity, precision, 'number needed to read' (NNR) and 'number unique' included by individual biomedical databases. MEDLINE, Embase, Cochrane Central Register of Control Trials (CENTRAL), and Cumulated Index to Nursing and Allied Health Literature (CINAHL) were searched without date or language restrictions up to December 31, 2022. Screening and data extraction were conducted in duplicate by pairs of independent reviewers. RCTs were included if they involved human subjects and HBOT was offered either on its own or in combination with other treatments. Results: Out of 5,840 different citations identified, 367 were included for analysis. CENTRAL was the most sensitive (87.2%) and had the most unique references (7.1%). MEDLINE had the highest precision (23.8%) and optimal NNR (four). Among included references, 14.2% were unique to a single database. Conclusions: Systematic reviews of RCTs in HBOT should always utilise multiple databases, which at minimum include MEDLINE, Embase, CENTRAL and CINAHL.

Equipoise: an important ethical consideration when contemplating participation in a randomised controlled trial of hyperbaric oxygen treatment in necrotising soft tissue infections.

A proposal for a large, multi-centre, randomised controlled trial investigating the role of hyperbaric oxygen treatment (HBOT) in necrotising soft tissue infections (NSTI) has led to much discussion locally and internationally about whether participation is ethical for a centre where stakeholders already consider HBOT standard practice. This article systematically addresses the concept of clinical equipoise specific to the role of HBOT in NSTI, and presents a series of considerations to be taken into account by key stakeholders at potential participating sites.

Effect of hyperbaric oxygen treatment on ischaemia-reperfusion injury in rats detorsioned after experimental ovarian torsion.

Introduction: This study aimed to investigate whether hyperbaric oxygen treatment (HBOT) could ameliorate ischaemia-reperfusion injury in a rat model of ovarian torsion-detorsion. Methods: Twenty-seven rats were divided among four groups: surgical sham rats (S) (n = 6) underwent identical anaesthesia and surgical incisions to other groups (n = 7 per group) but with no ovary intervention; torsion rats (T) underwent laparotomy, ovarian torsion, relaparotomy and sacrifice after three hours; torsion and detorsion rats (T/DT) underwent laparotomy, ovarian torsion (three hours), relaparotomy and detorsion, and sacrifice after one week; torsion, detorsion, hyperbaric oxygen rats (T/DT/HBOT) underwent laparotomy, ovarian torsion, relaparotomy and detorsion, and sacrifice after one week during which HBOT was provided 21 times (100% oxygen at 600 kPa for 50 min). In all groups blood collection for markers of oxidative stress or related responses, and ovary collection for histology were performed after sacrifice. Results: When the T/DT, and T/DT/HBOT groups were compared, 8-hydroxy-2'-deoxyguanosine (a marker of oxidative damage to DNA) and malondialdehyde (a product of lipid peroxidation) levels were lower in the T/DT/HBOT group. Anti-Mullerian hormone levels were higher in the T/DT/HBOT group compared to the T/DT group. In addition, oedema, vascular occlusion, neutrophilic infiltration and follicular cell damage were less in the T/DT/HBOT group than in the T/DT group. Conclusions: When biochemical and histopathological findings were evaluated together, HBOT appeared reduce ovarian ischaemia / reperfusion injury in this rat model of ovarian torsion-detorsion.

Secondary deterioration in a patient with cerebral and coronary arterial gas embolism after brief symptom resolution: a case report.

Introduction: Hyperbaric oxygen treatment (HBOT) is recommended for arterial gas embolism (AGE) with severe symptoms. However, once symptoms subside, there may be a dilemma to treat or not. Case presentation: A 71-year-old man was noted to have a mass shadow in his left lung, and a transbronchial biopsy was performed with sedation. Flumazenil was intravenously administered at the end of the procedure. However, the patient remained comatose and developed bradycardia, hypotension, and ST-segment elevation in lead II. Although the ST changes spontaneously resolved, the patient had prolonged disorientation. Whole- body computed tomography revealed several black rounded lucencies in the left ventricle and brain, confirming AGE. The patient received oxygen and remained supine. His neurological symptoms gradually improved but worsened again, necessitating HBOT. HBOT was performed seven times, after which neurological symptoms resolved almost completely. Conclusions: AGE can secondarily deteriorate after symptoms have subsided. We recommend that HBOT be performed promptly once severe symptoms appear, even if they resolve spontaneously.