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Number 4

Over the past four decades, hyperbaric oxygen (HBO2) therapy has played a prominent role in both the prevention and treatment of mandibular osteoradionecrosis (ORN). It has done so on the strength of laboratory observations and clinical reports, yet only limited efficacy data. This dual role has come under increasing scrutiny in the modern radiotherapy (RT) and surgical eras. The ability to spare healthy “non-target” tissue has markedly improved since the two-dimensional planning and delivery techniques in use when HBO2’s prophylactic value was first demonstrated. A recent study failed to identify this same benefit in patients who received high-precision imaging ..
Mr. Richard Clarke presents in this Journal his arguments against continued application of hyperbaric oxygen (HBO2) therapy to the pre-extraction neoadjuvant treatment or the treatment of frank mandibular ORN. In the same article he advocates a promising renewed interest in HBO2 as a radiosensitizer. Arguments against HBO2 prior to extractions are based on several papers which consistently include low-risk patients. The just-released HOPON trial reports a negative pre-extraction outcome for HBO2, but patients were enrolled with radiation doses as low as 50Gy. For advanced mandibular necrosis (Marx Stage III) requiring resection, fibular free flap reconstruction is advocated. A high ..
The descent is a critical part of a dive, both physically and mentally. Pulmonary ventilation, expressed as respiratory minute volume (RMV) and heart rate (HR) were recorded during fast and slow descents to 35 meters (m) in open water while breathing compressed air, and during swimming horizontally at moderate velocity at an 11-m depth. Values of both types of descents were compared with reference values recorded at 11 m, the “plateau” phase, halfway through the 35-m dives. It is hypothesized that the “slowdescent” and “plateau-phase” values will be less than ‘fast-descent values. Depth, cylinder pressure, water temperature and HR ..
Introduction: About 26% of diving-related fatalities are caused by cardiac disease, part of which might be associated with fatal arrhythmias. This raises the question as to whether fatal arrhythmias are being provoked by hyperbaric conditions themselves or if exercise or stress provokes the fatal arrhythmias in cases of underlying (ischemic) cardiac disease. Objective: To measure the influence of hyperbaric conditions (50 msw) on cardiac conduction and arrhythmias in professional divers by means of ECG. Methods: This is a prospective study on military divers in a hyperbaric chamber with continuous ECG monitoring using Holter registrations. Supraventricular and ventricular ectopy was registered during ..
Introduction: It is vital to protect divers from the cold, particularly in Arctic conditions. The insulating gas layer within the drysuit is crucial for reducing heat loss. The technical diving community has long claimed the superiority of argon over air as an insulating gas. Although argon is widely used, previous studies have shown no significant differences between the two gases. Owing to its lower heat conductivity, argon should be a better thermal insulating gas than air. Methods: The study aimed to determine whether argon is beneficial for reducing heat loss in divers during development of military drysuit diving equipment in ..
Introduction: To determine if hyperbaric oxygen (HBO2) therapy has an effect on diabetic blood glucose levels (BGL) and, if so, the extent of this effect. Also, to examine factors that exacerbate any observed effect.  Methods: This was a retrospective review of prospectively collected quality data on diabetics undergoing HBO2. Pre- and post-treatment BGL were recorded. Pre-treatment BGL <120 mg/dL received glucose supplementation. Hypoglycemia was defined as BGL <70 mg/dL. BGL <90 mg/dL was included as an elevated hypoglycemia threshold.  Results: 77 patients representing 1,825 treatments were included for analysis. No patient had deleterious side effects or required emergency care. BGL decreased ..
Introduction: The mining and tunneling industries are historically associated with hazardous exposures that result in significant occupational health concerns. Occupational respiratory exposures causing pneumoconiosis and silicosis are of great concern, silicosis being non-curable. This work demonstrates that compressed-air workers (CAWs) performing tunnel hyperbaric interventions (HIs) may be at risk for hazards related to bentonite exposure, increasing the likelihood of developing harmful illnesses including cancer. Bentonite dust inhalation may result in respiratory levels of silica exceeding acceptable industrial hygiene standards. Methods: A qualitative observational exposure assessment was conducted on CAWs while they were performing their HI duties. This was followed by ..
Introduction: Mastectomy skin flap necrosis represents a significant complication of breast reconstructive procedures and is reported to occur in 30%-52% of patients undergoing breast reconstruction. Early identification of ischemia and early initiation of hyperbaric oxygen (HBO2) therapy can mitigate the effects of ischemia and rescue otherwise non-viable breast flap tissue. Methods: We retrospectively examined the outcomes of HBO2 therapy in eight breasts with compromised mastectomy skin flaps between September 2015 and January 2017. Indocyanine green angiography (ICGA) was used to assess perfusion intraoperatively and post-HBO2 administration. Results: Seven patients were referred for HBO2 within 24 hours of mastectomy. One patient failed ..
Introduction/Background: The incidence of complications and number of critically ill patients in hyperbaric medicine is relatively low [1]. This poses a challenge to those tasked with educating trainees as well as maintaining the skills of staff. Hyperbaric medicine fellows may not be exposed to critical patient scenarios or complications of hyperbaric medicine during a one-year fellowship. Additional staff may be unfamiliar with these situations as well. The purpose of hyperbaric simulation curriculum is to train health care providers for rare situations. To our knowledge, this hyperbaric simulation curriculum is the first published use of simulation education in the specialty ..
The aim of this study was to establish the effect of combined therapy with hyperbaric oxygen (HBO2) therapy and verapamil, amlodipine or nicorandil on functional recovery and oxidative stress markers after ischemia in the isolated rat heart. The study included 48 rats (Wistar albino, male gender, eight weeks old, body weight 200Å}50g). All animals were exposed to HBO2 treatment over 14 days. Isolated heart rats were perfused by the Langendorff retrograde method at a constant coronary pressure of 70 cm H2O. After stabilization period the hearts were divided into the following groups: HBO2 group (animals exposed to only HBO2 preconditioning); HBO2 ..
Objective: Government programs have attempted to impact a recognized elevated risk for carbon monoxide (CO) poisoning among minority racial and ethnic groups. This study sought to describe U.S. mortality due to unintentional, non-fire-related CO poisoning, examining the distribution and trends by race and ethnicity. Methods: CDC Wonder was used to extract and analyze data on all U.S. resident deaths from unintentional CO poisoning from 2000-2017, categorizing them by year, race, ethnic origin and gender. Results: The absolute number of unintentional CO deaths decreased from about 450 to 380 per year during the period studied, a number near totally accounted for by ..
We hypothesized that heart rate variability (HRV) can be used as a physiological monitor of exposures to hypercapnia. HRV was analyzed in 15 male subjects breathing air and then air plus 4%, 5% or 6% carbon dioxide (CO2). A progressive elevation in randomness of HRV best depicted as a divergence of data on Poincaré plots of self-similarity occurred as CO2 increased, and resolved when returning to ambient conditions. Results indicate that HRV may be useful as a prompt (< 2 minute) early warning of hypercapnia that occurs prior to overt symptomatology. 10.22462/06.08.2019.12
Nitric oxide (NO) may protect against gas bubble formation and risk of decompression sickness. We have previously shown that the crucial co-factor tetrahydrobiopterin (BH4) is oxidized in a dose-dependent manner when exposed to hyperoxia similar to diving conditions but with minor effects on the NO production by nitric oxide synthase. By manipulating the intracellular redox state, we further investigated the relationship between BH4 levels and production of NO in human endothelial cells (HUVECs). HUVECs were cultured with and without ascorbic acid (AA) and the glutathione (GSH) synthesis inhibitor buthionine sulfoximine, prior to hyperoxic exposure. The levels of biopterins and ..
While several published cases have reported tissue preservation with hyperbaric oxygen (HBO2) after frostbite, its routine use is not endorsed by expert consensus. We report a case of possible frostbite injury to the toes of both feet and the plantar surface of the left foot in a 17-year-old male patient. The exposure history included two episodes of rewarming followed by refreezing in the field during a hike through knee-deep snow without adequate clothing. The patient also sustained full-thickness ice abrasions to both anterior shins. The patient was evaluated within 60 minutes after self-rewarming. He was treated with 400 mg ..