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Report of the Hyperbaric Oxygen Safety Committee of the Undersea and Hyperbaric Medical Society This document was written and reviewed by members of the Safety Committee of the UHMS and approved by the UHMS Board of Directors Preface The Board of Directors of the Undersea and Hyperbaric Medical Society (UHMS) acknowledges the work of the authors and the UHMS Safety Committee. It is our hope that this publication will prove helpful to practitioners in the field of hyperbaric medicine. The subject matter in this guide refers to the medical fitness of inside attendants (IAs) to work in a compressed-gas environment. This publication does not replace or supersede any local, state or institutional code or standard. It is a guideline put together by experts in the field, to be used as a reference in evaluating the health and tness to work of multiplace IAs. Users of this publication are invited to visit the UHMS web site (www.membership.uhms.org) for more information and are invited to email comments or questions to uhms@uhms.org. DOI: 10.22462/03.04.2018.11  

[Letter] DOI: 10.22462/03.04.2018.10

Acute idiopathic sudden sensorineural hearing loss (ISSNHL) following lumbar spinal surgery is an exceedingly rare phenomenon. This paper presents a case of ISSNHL presenting acutely after lumbar spine decompression and fusion treated with transtympanic steroids and hyperbaric oxygen (HBO2) therapy. It also presents the ironic case of SSNHL secondary to presumed viral pathology sustained by the patient’s operative surgeon who was treated with transtympanic steroids and HBO2 as well. Proposed etiologies of the patient’s ISSNHL include: hypo- tension, prone operative position, malfitted/malpositioned headrest, microemboli from a cell-saver, and nitrous oxide anesthesia. The role of systemic hypotension as an etiology of ISSNHL is discussed given the fact that there are no reported cases of ISSNHL in orthopedic procedures performed with permissive hypotension. The initiation of steroids and HBO2 therapy has been shown to be an effective treatment for ISSNHL when started within 14 days of symptom onset. HBO2 and transtympanic steroids were initiated 10 days earlier in the operative surgeon, which showed to be a better treatment modality compared to the postoperative patient. ISSNHL in the acute postoperative period of lumbar spinal fusion surgery presents a unique treatment dilemma because systemic steroids are routinely avoided over concerns of pseudarthrosis. Of the seven documented cases of ..

Introduction: CrossFit is a physical fitness program characterized by high-intensity workouts that can be associated with serious injury. Acute compartment syndrome in the upper limbs is a rare occurrence. It may occur after intense physical exercise, and its usual treatment is surgical. Hyperbaric oxygen therapy is a treatment described as adjunctive in cases of compartmental syndrome. Presentation: We describe the case of a CrossFit practitioner who, after intense training, developed progressive symptoms of rhabdomyolysis and acute bilateral arm compartment syndrome, who was successfully treated with hyperbaric oxygen therapy and required no fasciotomy as surgical treatment. Conclusion: Acute compartment syndrome in the arms after intense physical exercise is a rare occurrence that should be suspected by practitioners of physical activity experiencing intense, disproportionate and progressive pain. In the case presented, hyperbaric oxygen therapy was successfully used in the treatment of the disorder, with satisfactory progress, and without the need for a surgical fasciotomy as therapy. DOI: 10.22462/03.04.2018.8

Introduction: Patients with prior primary spontaneous pneumothorax (PSP) frequently seek clearance to dive. Despite wide consensus in precluding compressed-air diving in this population, there is a paucity of data to support this decision. We reviewed the literature reporting the risk of PSP recurrence. Methods: A literature search was performed in PubMed and Web of Science using predefined terms. Studies published in English reporting the recurrence rate after a first PSP were included. Results: Forty studies (n=3,904) were included. Risk of PSP recurrence ranged 0-67% (22 ± 15.5%; mean ± SD). Mean follow- up was 36 months, and 63 ± 39% of recurrences occurred during the first year of follow-up. Elevated height/weight ratio and emphysema-like changes (ELCs) are associated with PSP recurrence. ELCs are present in 59%-89% (vs. 0-15%) of patients with recurrence and can be detected effectively with high-resolution CT scan (sensitivity of 84-88%). Surgical pleurodesis reduces the risk of recurrence substantially (4.0±4% vs. 22±15.5%). Conclusions: Risk of PSP recurrence seems to decline over time and is associated to certain radiological and clinical risk factors. This could be incremented by the stresses of compressed-air diving. A basis for informed patient-physician discussions regarding future diving is provided in this review. DOI: 10.22462/03.04.2018.7

Introduction: Hyperbaric oxygen (HBO2) therapy and use of enriched air can result in oxidative injury affecting the brain, lungs and eyes. HBO2 exposure during diving can lead to a decrease in respiratory parameters. However, the possible effects of acute exposure to oxygen-enriched diving on subsequent spiro- metric performance and oxidative state in humans have not been recently described recently. We aim to investigate possible effects of acute (i) hyperbaric and (ii) hyperbaric hyperoxic exposure using scuba or closed-circuit rebreather (CCR) on subsequent spirometry and to assess the role of oxidative state after hyperoxic diving. Methods: Spirometry and urine samples were obtained from six well-trained divers (males, mean ± SD, age: 43.33 ± 9.16 years; weight: 79.00 ± 4.90 kg; height: 1.77 ± 0.07 meters) before (CTRL) and after a dive breathing air, and after a dive using CCR (PO2 1.4). In the crossover design (two dives separated by six hours) each subject performed a 20-minute session of light underwater exercise at a depth of 15 meters in warm water (31-32°C). We measured urinary 8-isoprostane and 8-OH- 2-deoxyguanosine evaluating lipid and DNA oxidative damages. Results: Different breathing conditions (air vs. CCR) did not significantly affect spirometry. A significant increase of 8-OH-dG (1.85 ± 0.66 vs. 4.35 ± ..

On the island Nation of Guam, the United States Department of Defense has stationed military personnel from every service branch. Guam is utilized as a strategic waypoint for the U.S. military in the Pacific theater. As the largest service branch in the region, the Navy has placed a few Diving Medical Officers in Guam to collectively manage and treat patients with recompression therapy. Guam is also a popular tourist destination, with multiple recreational diving companies certifying individuals who are looking to take advantage of the beautiful warm water and exotic marine life. Unfortunately, with an increase in training and certifying inexperienced divers, came an increase in the operational tempo of the U.S. Navy’s recompression chamber on Guam. The recompression chamber on Naval Base Guam (NBG) has been treating patients since 1971. With the only multiplace chamber in the Mariana Islands, Diving Medical Officers, with the accompanying chamber staff, treat military personnel, active-duty sponsored patients and civilian patients. Treating civilian patients by military providers through military treat- ment facilities presents multiple issues that must be addres- sed in an effort to provide efficient quality medical care. This article reviews the records, documents, and activity of the NBG chamber over the last four ..

Many aspects of the physiological stress related to the exposure to the hyperbaric environment have been studied, but no research has been made to evaluate the impacts of scuba diving on heart rate variability (HRV). We investigated the effects of a simulated dive to 557 KPa (45 meters of salt water) for a 30-minute bottom time on the frequency and time domains estimators of HRV. Electrocardiogram records were obtained with superficial electrodes for 30 minutes before the simulated dive and, subsequently, for one hour after the dive. Each of these time-series was then subdivided into non-overlapping windows of 256 consecutive R-R in- tervals. A control group was submitted to the same proto- col, breathing the same gases used in the simulated dive, while not being exposed to the hyperbaric environment. In the control group we observed a significant increase in SDNN (the square root of the variance of the R–R intervals), RMSSD (the square root of the mean squared differences of successive R-R intervals), and in two bands (high and low) of the power spectrum of frequencies. The subjects in the simulated dive presented only an increase in the low frequency estimator without any further relevant changes in other estimators ..

One of carbon monoxide’s several mechanisms of toxicity is binding with circulating hemoglobin to form carboxyhemoglobin, resulting in a functional anemia. While patients with carbon monoxide poisoning are often said to be “cherry-red,” such discoloration is rarely seen. Carboxyhemoglobin levels cannot be measured with conventional pulse oximetry, can be approximated with pulse CO-oximetry, and are most accurately measured with a laboratory CO-oximeter. Carboxyhemoglobin levels are quite stable and can be accurately measured on a transported blood sample. For clinical purposes, arterial and venous carboxyhemoglobin levels can be considered to be equivalent. Carboxyhemoglobin levels are typically lower than 2% in non-smokers and lower than 5% in smokers. A level over 9% is almost always due to exogenous carbon monoxide exposure, even among smokers. Conversely, a low level does not exclude significant exposure under certain circumstances. As carboxyhemoglobin levels of poisoned patients do not correlate with symptoms or outcome, their greatest utility is a marker of exposure. DOI: 10.22462/03.04.2018.3

Purpose: Hyperbaric oxygen (HBO2) therapy is used to improve the survival of compromised flaps. Compromised flaps are complications encountered postsurgically, or in traumatic degloving or avulsion injuries. Failed flaps lead to persistence of the defect, requirement of another donor site, and psychosocial sequelae. Although evidence of the benefit of HBO2therapy is significant, there is no consensus on the optimal treatment regimen. The purpose of this study is to examine whether twice-daily treatments (BID HBO2) provide additional benefit compared to daily treatments (QD HBO2) in a rat compromised random flap model. Method: A rat random flap model was used with subjects divided into three groups: 1) control group; 2) QD HBO2; and 3) BID HBO2, where HBO2 was performed with 100% oxygen at 2.5 atmospheres absolute/ATA (253 kPa) for 90 minutes. After 10 days, areas of flap necrosis were measured and biopsies were taken for histologic analysis. Statistical analysis was performed using ANOVA and paired t-tests. A P-value <0.05 was considered significant. Result: Both treatment groups had significantly increased mean flap survival compared to controls (P<0.05). There was no significant difference in flap survival between the QD and BID groups. Capillary proliferation in the QD group was increased compared with controls. Conclusion: Both QD and BID HBO2 protocols can ..

Background: In prior military randomized trials, participants with persistent symptoms after mild traumatic brain injury (TBI) reported improvement regardless of receiving hyperbaric oxygen (HBO2) or sham intervention. This study’s objectives were to identify outcomes for future efficacy trials and describe changes by intervention. Methods: This Phase II, randomized, double-blind, sham- controlled trial enrolled military personnel with mild TBI and persistent post-concussive symptoms. Participants were ran- domized to receive 40 HBO2 (1.5 atmospheres absolute (ATA), >99% oxygen, 60 minutes) or sham chamber sessions (1.2 ATA, room air, 60 minutes) over 12 weeks. Participants and evalua- tors were blinded to allocation. Outcomes assessed at baseline, 13 weeks and six months included symptoms, quality of life, neuropsychological, neurological, electroencephalography, sleep, auditory, vestibular, autonomic, visual, neuroimaging, and laboratory testing. Participants completed 12-month questionnaires. Intention-to-treat results are reported. Results: From 9/11/2012 to 5/19/2014, 71 randomized parti- cipants received HBO2 (n=36) or sham (n=35). At baseline, 35 participants (49%) met post-traumatic stress disorder (PTSD) criteria. By the Neurobehavioral Symptom Inventory, the HBO2 group had improved 13-week scores (mean change -3.6 points, P=0.03) compared to sham (+3.9 points). In participants with PTSD, change with HBO2 was more pronounced (-8.6 vs. +4.8 points with sham, P=0.02). PTSD symptoms also improved in the HBO2 group, and more so ..