Number 2

DOI: 10.22462/04.06.2020.19

DOI: 10.22462/04.06.2020.18

DOI: 10.22462/04.06.2020.17

DOI: 10.22462/04.06.2020.16

DOI: 10.22462/04.06.2020.15

Sudden sensorineural hearing loss (SSNHL) presents as an abrupt onset of hearing loss; 88% of these presentations are idiopathic (ISSHL). Many mechanisms of injury and etiopathologies have been postulated, but they share a common result – hypoxia of the organ of Corti leading to hair cell-cilia fusion, synaptic, dendritic swelling and sustained depolarization. Of all of the various treatments tried, only corticosteroids and hyperbaric oxygen (HBO2) therapy have shown benefit in randomized controlled trials (RCTs). This paper reviews the pathophysiology of SSNHL, the variety of treatments studied, and the best evidence (both retrospective case controlled and prospective randomized controlled studies) for the use of HBO2 and corticosteroids. The best results are obtained when these two treatments are combined and initiated within 14 days of symptom onset. HBO2 is given at 2-2.5 ATA for 90 minutes for 10-20 sessions. Steroids should be dosed at 1mg/kg/day and slowly tapered over two to three weeks. If a patient is not a good candidate for or refuses systemic steroids, good results have also been obtained using intratympanic (IT) steroids in combination with HBO2. Patients should be followed by and otolaryngologist before, during and following HBO2. For severe hearing loss treatment with HBO2 improves ..

We report the case of a 42-year-old commercial diver who presented with palpitations, arthralgia, tachypnea and vomiting after three hours of repetitive dives to 25-30 meters below sea level(msw). He was diagnosed with severe decompression sickness (Type II DCS) based on his dive history, his abrupt ascent to the surface within minutes, and systemic symptoms with mild hypovolemic shock. Besides remarkable cutis marmorata on the torso, the patient was also found positive for diffuse branch-like pneumatosis in the liver, mesentery and intestines on an abdominal computed tomography (CT). His vitals were relatively stable, with a soft distended abdomen and mild tenderness over the right upper quadrant. He was treated with hyperbaric oxygen (HBO2) treatment in addition to essential crystalloid resuscitation. The abdominal pneumatosis resolved completely after two HBO2 sessions. Post-diving intra-abdominal pneumatosis is a rare complication of DCS. In our case it was difficult for dive doctors to diagnose promptly because an emergency abdominal CT was not a routine for potential DCS cases. We propose that a contrast-enhanced abdominal CT, which usually involves a intravenous injection of imaging agent, should be considered in emergency management of these patients, especially when they present with gastrointestinal symptoms.  DOI: 10.22462/04.06.2020.13

Hyperoxic myopia is a phenomenon reported in individuals who have prolonged exposure to an increased partial pressure of oxygen (PO2) and subsequently have a myopic (nearsighted) change in their vision. To date, there are numerous accounts of hyperoxic myopia in dry hyperbaric oxygen treatment patients; however, there have been only three confirmed cases reported in wet divers. This case series adds four confirmed cases of hyperoxic myopia in wet divers using 1.35 atmospheres (ATM) PO2 at the Navy Experimental Diving Unit (NEDU). The four divers involved were the first author’s patients at NEDU. Conditions for two divers were confirmed via record review, whereas the other two divers were diagnosed by the first author. All subjects were interviewed to correlate subjective data with objective findings. Each subject completed five consecutive six-hour hyperoxic (PO2 of 1.35 ATM) dives with 18-hour surface intervals. Each individual was within the U. S. Navy Dive Manual’s standards for general health. Visual acuity was measured prior to diving. Within three to four days after diving, the individuals reported blurry vision with an associated myopic refraction shift. Each diver had spontaneous resolution of his myopia over the next two to three weeks, with no significant residual symptoms. ..

Background: Cold-water immersion impairs manual dexterity when finger temperature is below 15˚C. This exposes divers to increased risk of error. We hypothesized that whole-body active heating would maintain finger temperatures and dexterity during cold-water immersion.  Methods: Twelve subjects (six males) (22±2 years old; BMI 23.9±2.5; body fat 16±6%) completed 60-minute head-out water immersion (HOWI) wearing a 7mm wetsuit and 3mm gloves in thermoneutral water (TN 25˚C) and cold water (CW 10˚C)while wearing a water-perfused suit (WP) with 37˚C water circulated over the torso, arms, and legs. Gross (Minnesota Manual Dexterity Test [MMDT]) and fine (modified Purdue Pegboard [PPT]) dexterity were assessed before, during and after immersion. Core body and skin temperatures were recorded every 10 minutes. Results: MMDT (TN -25±14%; CW -72±23%; WP -67±29%; p<0.05) and PPT (TN -16±9%; CW: -45±10%; WP: -38±13%; p<0.05) performance decreased during immersion. MMDT and PPT did not differ between CW and WP. Immediately following immersion gross dexterity was recovered in all conditions. Post-immersion fine dexterity was still impaired in CW (p<0.01), but not WP or TN. Core and skin temperatures decreased during immersion in CW and WP (p<0.05) but did not differ between CW and WP. Conclusions: Manual dexterity decreased during immersion. Dexterity was further impaired ..

The definition of medication-related osteonecrosis of the jaw (MRONJ) includes a stage 0 presentation where exposed bone, the hallmark of this condition, is absent. Numerous management strategies have been recommended for MRONJ including hyperbaric oxygen (HBO2) therapy. This report describes a 64-year-old woman with stage 0 MRONJ of the bilateral mandible, refractory to clindamycin and local debridement, who was subsequently managed successfully with amoxicillin/clavulanate and HBO2 therapy. The authors also explore the current literature on the pathophysiology of MRONJ and the potential role of hyperbaric oxygen in its treatment. DOI: 10.22462/04.06.2020.10

Acute limb ischemia (ALI) as a complication of acute carbon monoxide (CO) poisoning is rare. Several reports have utilized hyperbaric oxygen therapy (HBO2) as an adjunctive therapy for peripheral arterial diseases. However, no study has yet described the use of HBO2 for ALI precipitated by CO poisoning. Herein we report successful limb salvage achieved with adjunctive HBO2 and conventional therapies in a patient with CO-induced ALI. A 69-year-old man was admitted with acute CO poisoning; ALI of both lower extremities occurred on hospitalization day 3. Pre-existing risk factors for ALI other than CO were not definite. After conventional treatments including catheter-directed thrombolysis and endovascular thrombectomy, the right-side lesion remained and a left-side lesion was newly developed. In addition to prior therapies, 47 sessions of serial HBO2 were administered as adjunctive therapy, resulting in limb salvage. Acute CO poisoning can cause ALI as a rare complication. HBO2 may be utilized as an adjunctive treatment in ALI. DOI: 10.22462/04.06.2020.9

Introduction: Health care workers are vulnerable to workplace violence, including active shooter incidents. Little is known about how firearms could damage monoplace chamber acrylic and whether a breached pressurized chamber presents additional threat to the patient or bystanders. Methods: In a remote area where firearm discharge is permitted, we tested the durability of sections of monoplace hyperbaric chamber acrylic under various firearm discharges. Firearms were discharged at acrylic sections from a distance of 17 feet at 45 degrees and 10 degrees from perpendicular while wearing protective gear. Firearm calibers ranged from .22 caliber handgun to 5.56 mm AR-15 rifle. We also conducted similar testing on a monoplace hyperbaric chamber pressurized with >99% oxygen to a differential pressure of 14.7 psig (2.0 atmospheres absolute at sea level). Handguns were remotely fired at a distance of 12 feet from the chamber (30 degrees from perpendicular), while the rifles were fired at a distance of 60 feet from the chamber. Results: Higher caliber handguns penetrated or fractured the acrylic sections only after multiple shots. The tested rifles caused full-thickness penetration and fracture with a single shot. However, the pressurized monoplace hyperbaric chamber required two shots from the AR-15 rifle, separated by approximately 60 mm, ..

Introduction: Hyperbaric oxygen (HBO2) therapy is the use of oxygen or gas mixtures at a pressure above atmospheric pressure for therapeutic purposes. This treatment is used in numerous pathological processes. Its main side effect is middle ear barotrauma (MEB), which represents a great concern for iatrogenic HBO2 therapy. The aim of this work is to describe this adverse event in order to highlight clinical elements that can contribute to its prevention and management. Methods: We conducted a five-year retrospective study from January 2013 to December 2017, where 2,610 patients were selected, in the Hyperbaric Medicine Centre, Sainte- Marguerite Hospital of Marseille, France. Results: 262 patients experienced MEB after HBO2, representing a prevalence of 10.04% and incidence of 0.587%. Their average age was 55 ± 19 years. Women were more affected than men. We have not highlighted a seasonality to this condition. Risk factors were: age older than 55 years, female gender, ear, nose and throat history (cancer, radiotherapy, infections or allergies, malformations or benign tumors), general history (smoking, obstructive breathing disorders, thyroid disorders and obesity), HBO2-approved indications of sudden deafness and delayed wound healing, and altered tympanic mobility on initial examination. Although the benign stages of Haines-Harris classification were the most ..

Simulation (SIM) can be used in the quality improvement process to discover latent risk threats (LRTs) by running in-situ simulation cases in the clinical environment. We utilized this methodology in the hyperbaric chamber to run six in-situ SIM sessions between February 2017 and January 2019. The debriefing portion of each SIM was used to discuss and document all discovered LRTs. These safety threats were aggregated and categorized, resulting in a total of 22 unique LRTs. LRTs included problems or challenges with equipment, team education, policy/processes, communications, and medications. At a three-month follow-up, the hyperbaric leadership team had addressed each of the 22 unique LRTs. SIM can be used to identify, categorize and prioritize LRTs in an effective manner, in order to improve the health care delivery system in a hyperbaric medicine department. DOI: 10.22462/04.06.2020.6

Simulated flight in a hypobaric chamber is a fundamental component in the physiological training of aviators. Although rare, there is always a risk of decompression sickness (DCS) in trainees during hypobaric hypoxia training. In this study we aimed to determine the incidence of altitude-induced DCS and the symptoms manifested in trainees and inside chamber observers (ICOs) during the training sessions. We retrospectively reviewed the records of DCS cases during the period of January 1, 2011, and October 1, 2018. The records of 6,657 trainees and 615 ICOs were evaluated. The gender distribution in 6,657 trainees was 6,578 (98.81%) male and 79 (1.19%) female. The numbers of DCS cases in trainees and ICOs were six (0.09%) and two (0.33%), respectively [(ICOs versus trainees – odds ratio (OR): 3.574; 95% CI 0.720–17.744;  (p > 0.05)]. All ICOs were male; no DCS incident was observed among female trainees. Recompression treatments were applied on site, and complete recovery was achieved in all cases. Overall DCS incidence was found to be 0.11% among the 7,193 male subjects, which included trainees and ICOs. The higher incidence of DCS in ICOs was attributed to the physical activities performed at altitudes by ICOs. In such training, established instructions ..

The fraction of nitric oxide in exhaled gas (FENO) is decreased after exposure to hyperoxia in vivo, although the mechanisms for this decrease is not clear. A key co-factor for nitric oxide synthase (NOS), tetrahydrobiopterin (BH4), has been shown to be oxidized in vitro when exposed to hyperoxia. We hypothesized that the decrease of FENO is due to decreased enzymatic generation of NO due to oxidation of BH4. The present study was performed to investigate the relationship between levels of FENO and plasma BH4 following hyperoxic exposure in humans. Two groups of healthy subjects were exposed to 100% oxygen for 90 minutes. FENO was measured before and 10 minutes (n = 13) or 60 minutes (n = 14) after the exposure. Blood samples were collected at the same time points for quantification of biopterin levels (BH4, BH2 and B) using LC-MS/MS. Each subject was his or her own control, breathing air for 90 minutes on a separate day. Hyperoxia resulted in a 28.6 % decrease in FENO 10 minutes after exposure (p < 0.001), confirming previous findings. Moreover, hyperoxia also caused a 14.2% decrease in plasma BH4 (p = 0.012). No significant differences were observed in the group measured ..

  Roflumilast is an inhibitor of phosphodiesterase-4 (PDE4) and can suppress the hydrolysis of cAMP in inflammatory cells, conferring anti-inflammatory effects. This study aimed to investigate the protective effects of roflumilast on hyperoxia-induced acute lung injury (HALI) in a rat model. Male Sprague-Dawley rats were randomly assigned into: control group; HALI group; 2.5 mg/kg roflumilast group; and 5 mg/kg roflumilast group. Rats were pressurized to 250 kPa with pure oxygen to induce lung injury. In the roflumilast groups, rats were orally administered with roflumilast at 2.5 or 5 mg/kg once before hyperoxia exposure and once daily for two days after exposure. Rats were sacrificed 72 hours  after hyperoxia exposure. The lung tissues were collected for the detection of lung water content, inflammatory cytokines and NF-κB/p-NF-κB protein expression, and the bronchoalveolar lavage fluid was harvested for the measurement of protein concentration and lactate dehydrogenase activity. Results showed roflumilast at different doses could significantly reduce lung edema, improve lung pathology and reduce the expression of inflammatory cytokines in the lung. The protective effects seemed to be related to the dose of roflumilast. Our study indicates roflumilast has the potential as a medication for the treatment of HALI.  DOI: 10.22462/04.06.2020.3

Objective: To determine whether hyperbaric oxygen (HBO2) therapy be effective to improve hypoxemia for severe COVID-19 pneumonia patients. Method: Two male patients ages 57 and 64 years old were treated. Each met at least one of the following criteria: shortness of breath; respiratory rate (RR) ≥30 breaths/minute; finger pulse oxygen saturation (SpO2) ≤93% at rest; and oxygen index (P/F ratio: PaO2/FiO2 ≤300 mmHg). Each case excluded any combination with pneumothorax, pulmonary bullae or other absolute contraindications to HBO2. Patients were treated with 1.5 atmospheres absolute HBO2 with an oxygen concentration of more than 95% for 60 minutes per treatment, once a day for one week. Patients’ self-reported symptoms, daily mean SpO2 (SO2), arterial blood gas analysis, d-dimer, lymphocyte, cholinesterase (che) and chest CT were conducted and measured.  Results: For both patients, dyspnea and shortness of breath were immediately alleviated after the first HBO2 treatment and remarkably relieved after seven days of HBO2 therapy. The RR also decreased daily. Neither patient became critically ill. The decreasing trend of SO2 and P/F ratio was immediately reversed and increased day by day. The lymphocyte count and ratio corresponding to immune function gradually recovered. D-dimer corresponding to peripheral circulation disorders and serum cholinesterase, reflecting liver ..

Recently the internet has been abuzz with new ideas to treat COVID-19, including hyperbaric oxygen (HBO2) therapy, undoubtedly driven by the fact that until recently there have been few therapeutic options for this highly contagious and often lethal infection. A series of five patients from Wuhan, China, has been reported to the UHMS and their features summarized [1]. Some groups have subsequently promoted HBO2 for COVID-19 infections, largely based upon two possible rationales. The first is treatment of hypoxemia, which is the major indication for endotracheal intubation in this condition. The second proposed rationale for hyperbaric oxygen is its potential anti-inflammatory effect. DOI: 10.22462/04.06.2020.1