Number 4

10.22462/06.08.2019.16

10.22462/06.08.2019.15

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 oral pentoxifylline three times a day and HBO2 at 2.4 atmospheres absolute for 90 minutes twice a day for a total of 13 treatments. Therapy was initiated approximately two hours from the estimated time of rewarming. Both feet recovered full sensation, and the patient had no tissue loss on his feet and and no functional impairment. The patient was followed for 12 months from injury. This case report highlights the difficulty health care providers face to accurately diagnose frostbite within the first 24 hours of injury, prior to development of more definitive signs and symptoms. Early treatment during this critical ..

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 GSH were determined in cell lysates while the production of NO was determined in intact cells. Omitting AA resulted in a 91% decrease in BH4 levels (0.49 Å} 0.08 to 0.04 Å} 0.01 pmol/106 cells, p<0.001) at 20 kPa oxygen (O2), and 88% decrease (0.24 Å} 0.03 to 0.03 Å} 0.01 pmol/106 cells, p=0.01) after exposure to 60 kPa O2. The NO generation was decreased by 23% (74.5 Å} 2.2 to 57.3 Å} 5.6 pmol/min/mg protein, p<0.001) at 20 kPa O2, but no significant change was observed at 60 kPa O2. GSH depletion had no effects on the NO generation. ..

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

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 the decrease in deaths occurring among non-Hispanic/ Latino whites. The number of deaths among the remainder of the population did not significantly change. However, greater growth in minority populations resulted in a similar decline in the mortality rate between non-Hispanic/ Latino whites and the combined minority population. The decline in combined minority death rate resulted from a decrease in the Hispanic/Latino white rate. Death rate did not decline in the black or African American population. Conclusions: All minority groups continue to display a disproportionate number of unintentional non-fire-related CO poisoning deaths compared to non-Hispanic/Latino whites. The decrease in U.S. deaths from ..

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 + verapamil; HBO2 + amlodipine; and HBO2 + nicorandil (animals pretreated with HBO2 and appropriate pharmacological agent). Afterward, the hearts in all groups were subjected to 20-minute global ischemia and 30-minute reperfusion. Parameters of heart function were registered, including maximum and minimum rate of pressure development, systolic and diastolic left ventricular pressure, heart rate and coronary flow. Levels of pro-oxidants such as index of lipid peroxidation, measured as thiobarbituric acid-reactive substances, nitrites, levels of superoxide anion radicals and hydrogen peroxide were determined in coronary venous effluent. Changes in cardiac tissue were evaluated by hematoxylin and eosin staining. Obtained results clearly indicate that ..

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 of undersea and hyperbaric medicine. Materials and methods: Two simulation cases have been developed that involve a patient with oxygen toxicity during hyperbaric treatment as well as an ICU patient with mucous plugging. Results: Medical training simulations are an effective method of teaching content and training multiple roles in Undersea and Hyperbaric Medicine. Summary/Conclusions: A hyperbaric simulation curriculum is an achievable educational initiative that is able to train multiple team members simultaneously in situations that they may not encounter on a regular basis. We believe that this could be easily exported to other institutions for further education. 10.22462/06.08.2019.9

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 to improve despite starting hyperbaric treatment within 24 hours. All other patients manifested successful healing of their mastectomy skin flaps with acceptable cosmesis after 10 HBO2 treatments. The mean relative perfusion of the at-risk area was 13.8% (Å}3.7%) pre-HBO2 and 101.6% (Å}37.3%) post-HBO2. The average area at-risk pre-HBO2 was 17.1 cm2 and reduced to zero post-HBO2. Relative perfusion values after HBO2 were found to be 6.8 (Å}3.4) times greater than those measured prior to HBO2. Conclusions: A short course of HBO2 may be sufficient to successfully rescue at risk post-mastectomy breast flaps. ICGA is a useful adjunct for evaluating post-mastectomy breast ..

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 quantitative data collection using personal and area air sample techniques. The results were analyzed and interpreted using standard industrial hygiene principles and guidelines from NIOSH and OSHA. Results: Our work suggests bentonite dust exposure may be an emerging particulate matter concern among CAWs in the tunneling industry. Aerosolized bentonite particles may have potential deleterious effects that include pneumoconiosis and silicosis. Silicosis can result in the development of pulmonary carcinoma. Conclusions: The modern tunneling industry and required hyperbaric interventional tasks represent a potential public health and occupational concern for CAWs. This paper introduces the modern tunneling industry and the duties of CAWs, the ..

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 in 75.4% of treatments in this group, with a median decrease of 25 mg/dL (IQR=54 mg/dL; range of decreased 374 mg/dL to increased 240 mg/dL). A statistically significant greater percentage of treatments of patients with type 2 diabetes resulted in a decrease in BGL (1598 or 77.5%) compared to treatments of patients with type 1 diabetes (169 or 51.5%) (χ2(1, N=1767) =55.37, p<0.001). 1.1% of treatments had post-HBO2 serum glucose <90 mg/dL, and 0.2% of treatments had post-HBO2 serum glucose <70 mg/dL. The majority (70%) of patients with post-HBO2 BGL < 90 mg/dL were maintained on insulin alone (χ2(2, N=20) ..

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 Arctic water temperatures. Four divers completed 14 dives, each lasting 45 minutes: seven dives used air insulation and seven used argon insulation. Rectal and eight skin temperatures were measured from which changes in calculated mean body temperature (MBT) were assessed. Results: There was a significant reduction in area weighted skin temperature over time (0-45 minute) on air dives (ΔTskin = -4.16ÅãC, SE = 0.445, P < 0.001). On argon dives the reduction was significantly smaller compared to air dives (difference between groups = 2.26ÅãC, SE = 0.358, P<0.001). There were no significant changes in rectal temperatures, nor was a significant difference ..

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 hyperbaric conditions. RR, PR, QRS, QT and QTc intervals were calculated at 50 msw and compared with ECGs at rest. Results: Included were 17 male military divers who made 20 dives. A total of 10 PVCs, 45 PACs, four atrial runs and four atrial pairs were seen. Significant prolongation of the PR interval was seen and a decrease of in QRS duration at 50 msw. There was no significant change in the RR, QT and QTc intervals. Conclusions: In these divers, no clinically relevant arrhythmias were observed during wet dives in a recompression chamber at 50 msw. We observed a small prolongation ..

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 were recorded with a dive computer yielding time-averaged means (mRMV and mHR) for the descent and for plateau. Of the 18 divers included, 16 performed the fast descents and 11 made the slow descents. The fast descents (23 m∙min-1 vertically), performed with 0-8 fin kicks, yielded mRMVDescent=28 ambient L (aL)∙min-1, which is 82% higher (P<0.001) than mRMVPlateau of 15 aL∙min-1. Further, mHRDescent was121 beats∙min-1 23% higher (P<0.001), than mHRPlateau of 100 bpm. Slow descents (2.4 m∙min-1 vertically) yielded 17 aL∙min-1 with mHR=101 beats∙min-1, values only slightly higher than at Plateau. The 11-m dive (swimming horizontally) yielded 24 m∙min-1 with 32 ..

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 complication rate with free flaps is acknowledged but the magnitude of these complications is not discussed. A cost savings for this procedure is suggested, but no mention is made of the typical cost of the procedure ($90,000) or the requirement of a typical one-week hospital stay, including an initial one or two days in the ICU. Nor is mention made of the very low rate of subsequent dental rehabilitation. The success reported by Delainian, et al. employing pentoxifylline, Vitamin E and sometimes a bisphosphonate is equated to the four decades of HBO2 success with the Marx protocol for Stage I ..

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 and conformal RT. HBO2 therapy is under challenge as preferred treatment for early stage ORN. A recently introduced “fibroatrophic” mechanism contrasts with the hypovascular-hypocellular-hypoxic injury pattern that formed the basis for HBO2’s therapeutic use. This alternative pathophysiologic state appears to benefit from an oral antioxidant medication regimen. The continuing necessity of HBO2 in support of mandibular reconstruction for advanced ORN is in question. Microsurgery-based vascularized bone flaps increasingly represent standard care, invariably in the absence of perioperative HBO2. Renewed interest in hyperbaric oxygen as a radiation sensitizer offers some promise. Hypoxia remains a critical radio-resistant factor in many solid tumors. ..