World War II was approaching its end in Italy in 1944 when one of the worst train disasters in world history occurred near the small town of Balvano in the Apennine Mountains. The train did not derail or crash into something as in most major train disasters. Instead, it entered a mountainous railway tunnel, and when it emerged, over 500 passengers were dead from carbon monoxide poisoning. The event was not allowed to be publicized for almost two decades. This manuscript reconstructs the story of possibly the most significant incident of carbon monoxide mortality ever recorded.

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 HBO make it a unique tool for AVN and applied it in conjunction with the standard of care for our patient.

To investigate the effect of 6 ATA air/ oxygen treatment scheme and 2.8 ATA oxygen inhalation scheme on cerebral gas embolism.

Despite established exposure limits and safety standards, and the availability of carbon monoxide (CO) alarms, each year an estimated 50,000 people in the United States visit emergency departments for CO poisoning. Carbon monoxide poisoning can occur from brief exposures to high levels of CO or from longer exposures to lower levels. If the CO exposure is sufficiently high, unconsciousness and death occur quickly, and without symptoms. With non-lethal exposures to CO, common symptoms include headaches, nausea and vomiting, dizziness, general malaise, and altered mental status. Some patients may have chest pain, shortness of breath, and myocardial ischemia, and may require mechanical ventilation and treatment of shock. Individuals poisoned by CO often develop brain injury. As with brain injury from non- CO causes such as traumatic brain injury, the clinical expression of brain injury caused by CO poisoning includes the domains of cognition, affect, neurological, and somatic. Common problems are neurological: imbalance, motor weakness, neuropathies, hearing loss, tinnitus, Parkinson's-like syndrome, vestibular, gaze, auditory processing, cognitive, anxiety and depression, posttraumatic stress, personality change, persistent headaches, dizziness, sleep problems, and others. In addition, some will have cardiac or other problems. While breathing oxygen hastens the removal of carboxyhemoglobin (COHb), hyperbaric oxygen (HBO) hastens COHb elimination and favorably modulates inflammatory processes instigated by CO poisoning, an effect not observed with breathing normobaric oxygen. Hyperbaric oxygen improves mitochondrial function, inhibits lipid peroxidation transiently, impairs leukocyte adhesion to injured microvasculature, and reduces brain inflammation caused by CO-induced adduct formation of myelin basic protein. Based upon supportive randomized clinical trials in humans and considerable evidence from animal studies, HBO should be considered for all cases of acute symptomatic CO poisoning. Hyperbaric oxygen is indicated for CO poisoning complicated by cyanide poisoning, often concomitantly with smoke inhalation.

Submersion results in blood redistribution into the pulmonary circulation, causing changes in pulmonary compliance and increased cardiac preload. Few studies have compared incremental exercise to exhaustion (VO max testing) in a dry environment with exercise underwater. We hypothesized that the physiological effects of submersion would result in lower heart rate (HR), minute ventilation (V), and peak oxygen uptake (VO peak) compared with dry conditions.

Sudden sensorineural hearing loss (SSNHL) presents as the abrupt onset of hearing loss. Approximately 88% of SSNHL has no identifiable etiology and is termed idiopathic sudden sensorineural hearing loss (ISSHL). Hearing specialists have investigated ISSHL since the 1970s. Over the past 30 years, more than 800 articles, or one every two weeks, have been published in the English medical literature. ISSHL is the abrupt onset of hearing loss, usually unilaterally and upon wakening, that involves a hearing loss of at least 30 decibels (dB) occurring within three days over at least three contiguous frequencies. As most patients do not present with premorbid audiograms, the degree of hearing loss is usually defined by the presentation thresholds of the unaffected ear. Other associated symptoms include tinnitus, aural fullness, dizziness and vertigo. The historical incidence of ISSHL ranges from 5-20 cases/100,000 population, with approximately 4,000 new cases per annum in the United States. The true incidence is thought to be higher, as ISSHL is thought to be underreported. Interestingly, 4,000 cases annually calculate to 1.3 cases/ 100,000 in the United States; therefore, an incidence of 5-20/100,000 would translate to > 15,000 new ISSHL cases per annum in the United States. Recent literature has placed the annual ISSHL incidence in the United States as 27 cases/100,000, with a pediatric incidence of 11 cases/100,000. Other studies report that the incidence is increasing (160/100,000), especially in the elderly (77/100,000), and conclude that ISSHL is no longer rare. In 1984, Byl reviewed the literature and found the mean age of ISSHL presentation to be 46-49 years, with variation of incidence with age and an equal gender distribution. The presentation of ISSHL does not appear to have seasonal variations, uneven distributions of presentation throughout the year, or an association with upper respiratory infections, either prior to or following symptom onset. The spontaneous recovery is currently thought to be 30-60%.

When administering HBO , pressures can range from 1.4 atmospheres absolute (ATA) to 3 ATA. While different treatment profiles have been proposed, there is a paucity of literature comparing the effectiveness and risk profile associated with different pressures treating the same condition. Considering the therapeutic divergence, this study aims to survey Undersea and Hyperbaric Medical Society (UHMS) members on pressure modalities and their use in different clinical conditions.

Studies suggest that COVID-19 infections may have longer-term and more significant complications, even with mild or absent symptoms. This may predispose divers to pulmonary barotrauma, arterial gas embolisms, and reduced exercise tolerance, and impact physical and cognitive performance during diving. Military diving is physically, physiologically, and psychologically taxing on the individual. This study aims to assess the incidence of complications after COVID-19 infections in a cohort of active military divers and the incidence of diving-related injuries such as decompression sickness and barotrauma following recovery from acute COVID-19 infections. A single-center, retrospective cohort study of complications after COVID-19 infections was done in a cohort of the Republic of Singapore Navy (RSN) Naval Diving Unit (NDU) Divers and involved the collection of retrospective data for 329 military divers who were diagnosed with COVID-19 infection from 25 Mar 2020 and 13 Feb 2023. We found no clinical or subclinical complications after COVID-19 infection in our fully vaccinated, low-risk population of NDU divers after asymptomatic or mild COVID-19 infection. There were also no incidences of diving-related injuries related to COVID-19 after recovery from the acute illness. Based on the study results, it is recommended that all military divers with asymptomatic or mild COVID-19 infections return to military diving activities immediately after recovery from acute COVID-19 infection with resolution of symptoms. As existing guidelines recommend, divers with moderate to critical COVID-19 infection should be reviewed by a diving physician and undergo necessary investigations before returning to military diving.

This report details a case study of a non-smoking 33-year-old female nurse who developed occupational asthma as an Inside Attendant (IA) in a hyperbaric chamber. The report analyzes the nurse's medical history, working environment, and potential causes. After beginning work in the hyperbaric chamber, an IA experienced respiratory symptoms, including coughing, wheezing, and fatigue. Her symptoms improved during a break attending a hyperbaric nursing certification program but returned when she resumed work in the IA hyperbaric chamber. Spirometry confirmed airflow obstruction, and the IA was subsequently diagnosed with occupational asthma. As a result, the IA had to terminate their employment in the hyperbaric chamber. The literature review indicates that diving and hyperbaric exposure can negatively affect respiratory function, particularly in individuals susceptible to respiratory issues. We emphasize the necessity for further research on the effects of hyperbaric exposure on the respiratory system of IAs.

Middle ear barotrauma (MEBT) is the most common complication in providing hyperbaric oxygen therapy (HBO). This study explored the impact of altering the shape of the time-pressure curve with the aim of reducing the occurrence of MEBT and optimizing the HBO experience during the pressurization process. Four distinct mathematically derived protocols-Constant Pressure Difference (CPD), Constant Volume Difference (CVD), Constant Ratio (CR), and Inverted Constant Ratio (ICR)-were investigated using computer simulations on a simple ear model. Results indicated varying levels of ear strain during pressurization. The CR pressurization demonstrated balanced ear strain levels and outperformed other modalities in several measures, including the impact on the simulated ear cavity volume. The potential for enhanced patient comfort through the application of sophisticated pressurization protocols warrants further research to validate and extend the findings of this study in real-world HBO settings.

To determine the outcomes of patients receiving hyperbaric oxygen therapy for sudden sensorineural hearing loss and the impact of patient comorbidities on outcomes.

Arterial vascular occlusion is a rare complication of dermal filler injection. This case report describes the successful use of hyperbaric oxygen therapy in a patient with vascular occlusion after a permanent dermal filler was injected.

Arieli has previously demonstrated that the exposure metric K could be used to predict pulmonary oxygen toxicity (POT) based on changes in Vital Capacity (VC). Our previous findings indicate that the Equivalent Surface Oxygen Time (ESOT) allows the estimation of POT without loss of accuracy compared to K. In this work, we have further investigated POT recovery. The K metric assumes that the recovery of POT is to be controlled by exposure to pO. This results in a counterintuitively slow estimated recovery after exposure to low pO. Similarly, K overestimates POT during intermittent hyperoxic exposures. We used results from previous studies to train the parameters of a new ESOT recovery model. The predicted recovery of ESOT (ESOT) after initial hyperoxic exposure (ESOT) of duration t (h) and recovery time t (h) can be calculated as ESOT=ESOT · e with f=0.439 · t · 0.906. For intermittent exposures, the function ESOT(n)=(n · a · ln(b · n+1)+c) · t · pO will approximate POT (ESOT(n)) after n sessions of pO (atm) for time t (min) in each cycle. Parameters a, b, and c are specific for each cycling pattern. These ESOT functions will better predict the development of POT during intermittent hyperoxic exposures as well as recovery after a broader range of continuous hyperoxic exposures than K. We recommend limiting hyperoxic exposures in surface-oriented diving to ESOT=660, 500, and 450 for a maximum of one, five, and seven consecutive days, respectively. A minimum of 48 hours of recovery should follow. These limits can probably be relaxed for intermittent exposures.

In clinical management of carbon monoxide (CO) poisoning, serum cardiac enzyme biomarkers and electrocardiogram (ECG) are both highly recommended emergency check-ups to evaluate myocardial injuries. Medical imaging - including head CT or MRI - are not routine for CO poisoning emergency management. We herein report on a comatose patient who was diagnosed with cerebral infarction secondary to 24 hours previous acute CO poisoning, warned by a typical cerebral-type T waves on ECG in advance, and confirmed by a head MRI. Fortunately, the patient made a full recovery based on a timely treatment with medications and hyperbaric oxygen (HBO) therapy. We would like to propose that a vital, stable, conscious CO poisoning patient who remains a higher risk for hemorrhagic or ischemic stroke should be closely monitored for potential neurological abnormalities, and a continuous ECG monitoring should be reinforced throughout the treatment. A head MRI or CT is a priority in evaluating the secondary cerebral stroke and should be arranged immediately in the event of an abnormal ECG or if unusual new symptoms are apparent.

The assessment of rectal temperature and behavior is an important parameter in all patients for whom hyperbaric oxygen (HBO) therapy is used. The study aims to verify if there is less reduction in body temperature after HBO therapy in restless patients and their behavior during the therapeutic session. Clinical data from 217 HBO therapy sessions with 2 to 2,5 atmospheres absolute (ATA) were reviewed under therapy protocols of 30 (P1) or 45 (P2) minutes, covering 29 canines and 13 felines. Behavioral data, initial rectal temperature (iRT), final (fRT), and variation between them (RTv) of each patient were recorded. Parameters of oxygen concentration, humidity, temperature, and chamber flow rate were also recorded. Three of 217 patients experienced major adverse effects (seizure and auto-trauma). 144/217 HBO therapy session records were selected for statistical analysis. In P1 sessions, 33.3% of the canine and 33.3% of the feline patients were restless. In P2 sessions, 40.7% of the canine and 28.1% of the feline patients were restless. The study did not observe a correlation between vRT and patients' behavior (p> 0.089) or differences in vRT between quiet and restless patients. There was a difference between iRT and fRT only in canines submitted to P1 (p<0.001) and felines submitted to P2 (p<0.001). Older canine patients were more restless than young canine patients at P1 (p= 0.02). We conclude that there may be a reduction in the fRT of dogs and cats submitted to 2 ATA for 30 minutes and 2.5 ATA for 45 minutes, respectively.

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 (HBO) 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 HBO therapy, expecting decreases in bacterial proliferation, reduction in local edema, and improvement of host defense. HBO 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 HBO therapy. One month after starting HBO therapy, the wound was closed, and the pus discharge resolved completely. Four years have passed since the HBO therapy, and there have been no symptomatic or imaging relapses of RA.

Hyperbaric Oxygen Therapy (HBO) is a treatment modality that exposes patients to 100% oxygen at higher atmospheric pressures. Recently, HBO has emerged as a potential therapeutic option for various liver diseases, offering advantages such as improved tissue oxygenation, anti-inflammatory effects, enhanced wound healing, and potential hepatoprotective properties. Understanding the benefits of HBO in liver diseases can pave the way for novel therapeutic strategies and improved patient outcomes. This study aimed to investigate the hepatoprotective effect of HBO in arthritic rats treated with leflunomide (LEF) through anti-inflammatory and antioxidant pathways.

Preterm birth may significantly impair the functional and anatomical development of the respiratory system and could be a background for various life-long medical sequelae. Prematurity has been recently connected to changes in hypercapnic reactions at adult age. Altered reactions to pCO in premature-born subjects may impact breath-hold underwater exercises (freediving) results.

Decompression after diving may inevitably cause the production of bubbles in the body, even without protocol violation. Bubbles produced in the circulation may damage the vascular cells, leading to vascular dysfunction. In this study, five subjects were recruited and subjected to hyperbaric exposure (15 meters; 100 minutes). The function of the brachial artery was assessed by measuring diameter, systolic peak velocity (SPV), resistance index (RI), and flow-mediated dilation (FMD) of the brachial artery before and after hyperbaric exposure. Our results showed that hyperbaric air exposure slightly increased the diameter of the brachial artery and significantly increased its RI but reduced the FMD and markedly decreased the SPV. This study indicates that hyperbaric air exposure at low pressure may also alter the function of the brachial artery.

The Undersea and Hyperbaric Medical Society (UHMS) is at the forefront of advancing medical knowledge and promoting patient safety in the field of hyperbaric medicine. In the dynamic landscape of healthcare, physicians' critical role in overseeing hyperbaric oxygen treatment (HBO) cannot be overstated. This position statement aims to underscore the significance of physician involvement in delivering HBO and articulate UHMS's commitment to maintaining the highest standards of care and safety for patients undergoing hyperbaric treatments.

The term "intracranial abscess" (ICA) includes cerebral abscess, subdural empyema, and epidural empyema, which share many diagnostic and therapeutic similarities and, frequently, very similar etiologies. Infection may occur and spread from a contiguous infection such as sinusitis, otitis, mastoiditis, or dental infection; hematogenous seeding; or cranial trauma. Brain abscess usually results from predisposing factors such as HIV infection, immunosuppressive drug treatment, surgery, adjacent infection (i.e., mastoiditis, sinusitis, dental infection), or systemic infection causing bacteremia. Approximately 30% to 50% of infections are caused by contiguous spread of local infections. Hematogenous spread is responsible in around a third of cases, with the mechanism for the remainder not identifiable.