Number 1

Correction/Erratum: In the fourth quarter issue 2020 of the UHM Journal (46-5) we represented the NNT number (number-needed-to-treat) as “three (3)” rather than simply “3.” This appeared on Page 727 in the letter from Richard Clarke, CHT, National Baromedical Services, entitled “HBO2 for radiation cystitis.” The corrected section should have read: “Although not reported, the ‘Number Needed to Treat’ (NNT, an epidemiological measure used to communicate effectiveness of an intervention, and representing the average number of patients needed to be treated in order to produce one favorable outcome) was computed as an encouraging 3. This value was the same for the subjective Expanded Prostate Index Composite (EPIC) and objective Late Radiation Morbidity Grading Scheme (LRMGS) scores, rounded up by convention from 2.56 and 2.17, respectively.”

[ Letters} DOI: 10.22462/01.03.2020.19

[ Letters ] DOI: 10.22462/01.03.2020.18

Despite established exposure limits and safety standards as well as the availability of carbon monoxide (CO) alarms, each year 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. Common symptoms can 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 manifested by neurological problems, including cognitive sequelae, anxiety and depression, persistent headaches, dizziness, sleep problems, motor weakness, vestibular and balance problems, gaze abnormalities, peripheral neuropathies, hearing loss, tinnitus, Parkinsonian-like syndrome, and other problems. In addition, some will have cardiac issues or other ailments. While breathing oxygen hastens the removal of carboxyhemoglobin (COHb), hyperbaric oxygen (HBO2) 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 the CO-induced adduct formation of myelin basic protein. ..

Carbon monoxide (CO) exposure is a prevalent cause of poisoning worldwide. The cardiac effects of CO poisoning are well described and can manifest as angina, myocardial ischemia or infarction, cardiogenic shock, and/or life-threatening arrhythmias. Atrial fibrillation has been associated with severe CO poisoning; however, few cases have described atrial fibrillation in acute CO poisoning with regard to hyperbaric oxygen (HBO2) therapy. Herein, we describe a case of severe CO poisoning that caused atrial fibrillation with successful conversion to sinus rhythm following HBO2 therapy and discuss implications for further research. DOI: 10.22462/01.03.2020.16

Carbon monoxide (CO) poisoning presents with many different cardiac effects, but one important presentation is its effect as a CO stress test to reveal underlying coronary artery disease (CAD). There are a limited number of publications detailing this phenomenon, but after CO intoxication it is important to suspect CAD in association with mild troponin leak or non-ST segment elevation myocardial infarction (NSTEMI) shown on electrocardiogram (EKG). We recently treated three patients with CO poisoning who had underlying CAD. In the first case a man presented to the emergency department with CO toxicity and an ST segment elevation myocardial infarction (STEMI), resulting in emergent angioplasty and the discovery of severe CAD. The second case involved an individual who presented with CO poisoning with rising troponin levels. An angioplasty discovered a stable 90% occlusion. The third case was a patient with CO poisoning and transient inferior T wave inversion EKG with borderline troponin elevation. Angioplasty showed only 30% occlusion, so the patient’s presentation was likely due to direct CO cardiac toxicity. These cases demonstrate the varied presentations that CO poisoning can have on patients with underlying heart disease. DOI: 10.22462/01.03.2020.15

Introduction: Altitude chamber exposures are used for training to allow aircrew to experience their hypoxia and pressure effect symptoms. Decompression illness (DCI) can occur subsequent to altitude chamber training or in operational aircraft when the cabin altitude is at least 18,000 feet. Definitive emergent treatment is hyperbaric oxygen (HBO2) to decrease bubble size, dissipate excess nitrogen hyperoxygenate tissue and reduce inflammation. Case report: A 27-year-old female underwent altitude chamber training to 25,000 feet. She developed tingling in both legs and left arm, headache, dizziness, malaise, then difficulty talking. She underwent two HBO2 treatments. Over the next 12 months she had paresthesia, decreased memory and cognitive function similar to symptoms seen following traumatic brain injury. She was referred 14 months after the event for evaluation. Using pre-deployment Automated Neuropsychological Assessment Metrics (ANAM) and serial tests over 58 HBO2 treatments, the patient demonstrated near-return to her pre-deployment test scores.  Discussion: The reason for HBO2 treatment was based on previous experience with chronic traumatic brain injury subjects where HBO2 improved outcome. The patient’s chronic neurological symptoms mimicked chronic TBI. The patient was unique in that baseline cognitive tests existed that could be used to monitor her changes during the treatment series. DOI: 10.22462/01.03.2020.14

Hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplantation (AHSCT) in both children and adults has been associated with significant morbidity and mortality. Early HC can occur within 48 hours of completing the chemotherapy conditioning regimen, is usually associated with agents such as cyclophosphamide, and generally resolves promptly. Late HC is commonly associated with BK and other viruses and can prove refractory to antiviral and supportive therapy. There are limited reports of hyperbaric oxygen (HBO2) therapy showing benefit for refractory HC cases. We describe our experience with salvage HBO2 for a 15-yearold male with refractory HC beginning one month post AHSCT and associated with BK virus. Despite supportive therapies including hyperhydration, forced diuresis, transfusions, intravenous and intravesical cidofovir, macroscopic hematuria persisted and resulted in post-obstructive acute renal failure, need for a suprapubic catheter, then bilateral percutaneous nephrostomy tubes. HBO2 was started two months after the AHSCT and one month after detection of BK viremia. In the week prior to starting HBO2 therapy the patient required transfusion with 25 units of red blood cells and seven units of platelets. After HBO2 was started his transfusion requirements progressively decreased, and he had return of renal function. He had no adverse effect ..

Background: Calcific uremic arteriolopathy (calciphylaxis) is a rare and highly lethal vascular disease. Vascular calcification with calcium depositions lead to ischemic ulcers associated with gangrene, severe pain and poor healing. Although hyperbaric oxygen (HBO2) therapy has been used in the treatment of calciphylaxis, evidence of its effectiveness is limited. Objective: To determine whether HBO2 therapy has a beneficial effect in the healing of calciphylaxis ulcers.  Methods: A search was made in PubMed using a comprehensive strategy to identify the effect of HBO2 on calciphylaxis wounds. Included in the analysis were studies published up to October 2018 involving a minimum of four patients receiving HBO2 therapy. Results: Ten retrospective (case) series were included. This review included a total of 131 patients with calciphylaxis who were treated with HBO2 therapy; of these, 58 patients (45%) had full response on HBO2 with complete wound closure. Regarding partial response, 17 of the patients (13%) experienced substantial wound improvement on different wound scale scores. Conclusion: Patients with calcific uremic arteriolopathy can benefit from HBO2. More research is needed using standardized wound scores. Outcomes related to quality of life and pain relief should also be assessed. DOI: 10.22462/01.03.2020.12

Aim: The aim of this study was to examine first aid measures applied in a large series of Australian dive-related fatalities to better determine where improvements can be made. Methods: The National Coronial Information System was searched to identify scuba diving and snorkeling-related cases reported to various Australian Coroners for the years 2001-2013 inclusive. Coronial documents examined included witness statements, police reports and ambulance and medical reports where available. Information relating to the recovery, rescue and/or resuscitation of the victims was extracted, compiled and analyzed. Results: 126 scuba diving and 175 snorkeling-related fatalities were identified during the study period, with airway management complications reported in one-third. Cardiopulmonary resuscitation was performed in three-quarters of the incidents. An automated external defibrillator was attached to 40 victims as a first aid measure, and shocks were indicated and delivered in five cases. Although three-quarters of the reports included no information about whether supplemental oxygen was provided, it was confirmed in 19% of both the scuba diving and snorkeling incidents. Conclusion: There were often considerable delays in the recognition, rescue and/or recovery of an unconscious snorkeler or diver and, consequently, the time to commencement of basic life support. Such delays can affect chances of survival and need to be minimized. Delivery ..

The purpose of this study was to investigate the effects of a single bout of heliox non-saturation diving on the cardiovascular system and cognitive function. Ten recreational scuba divers (10 males, ~35 years old) participated in this study. These subjects made two pool dives within a one-week interval, alternating gases with compressed air (21% O2, 79% N2) and with heliox (21% O2 and 79% He). The depth was to 26 meters over a 20-minute duration. The results showed that heliox diving significantly increased blood O2 saturation by 1.15% and significantly decreased blood lactate levels by ~57% when compared with air diving (P<0.05). However, there were no significant differences in resting heart rate, systolic or diastolic pressure, core body blood pressure, and pulse wave velocity between the heliox and air dives. The Stroop test showed that the heliox dive significantly increased cognitive function compared with the air dive in both the simple test (Offtime) and interference test (Ontime) (P<0.05). It was concluded that the heliox dive increases blood O2 saturation and decreases blood lactate concentration when compared with air dives. These conditions are likely to help divers reduce hypoxia in the water, reduce the risk of loss of consciousness, reduce ..

Introduction: 122,129 dives by 10,358 recreational divers were recorded by dive computers from 11 manufacturers in an exploratory study of how dive profile, breathing gas (air or nitrox [N2/O2] mixes), repetitive diving, gender, age, and dive site conditions influenced observed decompression sickness (DCSobs). Thirty-eight reports were judged as DCS. Overall DCSobs was 3.1 cases/104 dives.  Methods: Three dive groups were studied: Basic (live-aboard and shore/dayboat), Cozumel Dive Guides, and Scapa Flow wreck divers. A probabilistic decompression model, BVM(3), controlled dive profile variability. Chi-squared test, t-test, logistic regression, and log-rank tests evaluated statistical associations. Results: (a) DCSobs was 0.7/104 (Basic), 7.6/104 (Guides), and 17.3/104 (Scapa) and differed after control for dive variability (p<0.001). (b) DCSobs was greater for 22%-29% nitrox (12.6/104) than for 30%-50% nitrox (2.04/104) (p ≤ 0.0064) which did not differ from air (2.97/104). (c) For daily repetitive dives (<12-hour surface intervals (SI)), DCS occurred only following one or two dives (4.3/104 DCSobs; p<0.001) where SIs were shorter than after three or more dives. (d) For multiday repetitive dives (SIs < 48 hours), DCS was associated with high multiday repetitive dive counts only for Guides (p = 0.0018). (e) DCSobs decreased with age at 3%/year (p ≤ 0.0144). (f) Males dived deeper (p<0.001) but for less time ..

Background: Central retinal artery occlusion (CRAO) is a rare ocular-ischemic syndrome causing irreversible blindness. Its pathophysiology has not been clarified, and no targeted therapies are available yet. Hyperbaric oxygen (HBO2) therapy is an approved therapy for CRAO and has been shown to improve the visual acuity of CRAO patients safely. However, further clinical data are required to classify HBO2 therapy as a type-I general agreement for CRAO. Materials and Methods: Eleven patients with non-arteritic CRAO were enrolled. Patient demographics, medical history, detailed eye examinations, HBO2 therapy results, pre-/post- HBO2 therapy visual acuity measurements and genotypes for common thrombophilic mutations (Factor V G1691A Leiden, Factor II G20210A, MTHFR A1298C, MTHFR C677T, and PAI-1-675 4G/5G) were obtained. Results: Six patients (54%) responded to HBO2 therapy compared to five non-responders (46%). Patients admitted before 12 hours responded well to HBO2 therapy. No systemic diseases nor advanced age were statistically correlated to CRAO. A combination of mutations rather than single mutations for each patient could be seen as responsible for CRAO. No Factor V G1691A Leiden mutations and only one FII G20210A mutation were observed. Eight patients (72%) had MTHFR 677T allele, five patients (45%) had MTHFR 1298C allele, and 10 patients (91%) had the PAI-1-675 4G allele. Conclusion: Not ..

Purpose: Central retinal artery occlusion (CRAO) is an ophthalmic emergency with poor prognosis, despite diligent conventional treatment. According to the clinical recommendations of the Undersea and Hyperbaric Medical Society hyperbaric oxygen (HBO2) is a potentially beneficial treatment; however, the benefit of adjunctive HBO2 in patients with CRAO in Korea remains unclear. The present study aimed to evaluate the effect of adjunctive HBO2 in patients with CRAO. Methods: This registry-based observational study included adult patients who presented to the emergency department or ophthalmology outpatient department within 24 hours of the onset of CRAO symptoms. Data of patients from October 2016 to February 2019 were analyzed. The patients were categorized into two groups according to the use of adjunctive HBO2: no HBO2 and HBO2. Result: During the study period, 34 consecutive patients were enrolled, of which 19 were included in the study. In the total cohort, 10 patients (52.6%) were treated with adjunctive HBO2. There were no statistically significant differences in terms of age, sex, comorbidities, duration from symptoms onset to hospital visit, presence of the cilioretinal artery, and use of anterior chamber paracentesis between the two groups. The HBO2 group showed significantly higher change in best-corrected visual acuity than the no-HBO2 group (p=0.043). Conclusion: Patients with CRAO ..

Idiopathic sudden sensorineural hearing loss (ISSHL) is defined as unexplained hearing loss of at least 30 decibels (dB) occurring within 72 hours over at least three contiguous frequencies. ISSHL is common and has a significant effect on quality of life. Hyperbaric oxygen (HBO2) therapy is a medical treatment method that aims to increase the level of dissolved oxygen in the tissues. Correcting perilymph hypoxia is the goal of HBO2 therapy for ISSHL. In recent years, HBO2 therapy has been increasingly involved in the treatment of ISSHL. The medical records of 135 patients who had received HBO2 therapy for ISSHL were reviewed. Demographic properties of patients, severity of hearing loss, delay until HBO2 therapy, number of HBO2 therapy sessions and outcomes were evaluated. Findings of the present study are similar to most of previous studies that demonstrate that HBO2 therapy as adjunctive treatment results in an improvement of hearing. Early treatment is important for ISSHL, and HBO2 therapy is recommended in the early period, particularly within 14 days of onset. DOI: 10.22462/01.03.2020.6

Hyperbaric medicine is a relatively young specialty that remains in the blind spot of most doctors’ awareness. This study endeavors to identify the level of awareness of the indications for hyperbaric oxygen (HBO2) therapy among a doctor population in a developed country and factors which may improve referral rates. An anonymized questionnaire was distributed to doctors licensed to practice in Malta. Questions included physician specialty, demographics and previous exposure to diving and/or hyperbaric medicine. Moreover, two scoring systems were used to score subjects on HBO2-related topics. Binomial logistic regression models and generalized linear models were used in the statistical analysis. A total of 152 full replies were obtained and analyzed. Respondents who had visited a hyperbaric unit (HBU) (p=0.002) or attended a lecture on HBO2 (p=0.006) scored better than their counterparts, indicating better awareness of HBO2 indications and local chamber location. A previous HBU visit (p=0.001), being a hospital-based doctor (p=0.027) and a history of scuba diving (p=0.03) were associated with willingness to refer patients for HBO2 in the future. Encouraging visits to an HBU has been shown to be associated with multiple factors, which are expected to result in improved referral rates. Targeted educational sessions to doctors and ..

Background: Hyperbaric oxygen (HBO2) therapy can have a positive effect on wound healing, angiogenesis and blood flow. No prior study has described the effects of HBO2 therapy and gene expression of this process. The goal of our research was to show the effects of HBO2 and its impact at the molecular level on angiogenesis, proliferation, differentiation, oxidative stress, inflammation, and extracellular matrix formation. Live animal subjects were used for simulating the process of wound healing under standard conditions and under the influence of HBO2. Methods: Two experimental groups were created using injured rabbits (N=24), one group (N=12) treated with hyperbaric therapy twice a day and one (N=12) with standard wound care management. Wounds were surgical, uninfected, and in healthy animal test subjects. We compared the whole genomic analysis of the transcriptome with the use of microarray technology at three intervals during treatment.  Results: The induction of the wounds in rabbit skin increased expression of hundreds of genes in both treatment groups. The numbers of elevated and decreased genes gradually reduced as the wound healed. Gene expression analysis showed elevated expression of several genes associated with inflammation in both groups of injured animals. Genes connected to the process of angiogenesis, proliferation, differentiation, oxidative stress and ..

Background: Acute kidney injury (AKI) as a consequence of ischemia is a common clinical event that can lead to unacceptably high morbidity and mortality. Hyperbaric oxygen (HBO2) preconditioning has been shown to prevent ischemia-reperfusion injury (IRI) in different tissues.  Objectives: The aim of our study was to compare the effects of HBO2 preconditioning on renal hemodynamics, kidney function and oxidative stress in normotensive and spontaneously hypertensive rats that suffered kidney IRI. Methods: An experiment was performed on Wistar (normotensive) and spontaneously hypertensive rats (SHR). The animals were divided into the following experimental groups: sham-operated rats and rats with or without HBO2 preconditioning 24 hours before post-ischemic AKI induction. Treated rats were placed into experimental HBO2 chambers and exposed to pure oxygen twice a day for two consecutive days (2.026 bar of oxygen) for 60 minutes. AKI was performed the next morning. The right kidney was removed and the renal ischemia was performed by clamping the left renal artery for 45 minutes. Results: In this study, HBO2 preconditioning significantly improved disturbed renal hemodynamics, major markers of kidney function in plasma (creatinine, urea and phosphate) as well as antioxidant enzymes (superoxide dismutase and catalase) activities in erythrocytes after AKI induction. Also, HBO2 preconditioning decreased lipid peroxidation in plasma ..

Background: Hyperbaric oxygen therapy has been demonstrated to lower blood glucose levels in patients with diabetes. Continuous glucose monitoring (CGM) allows glucose monitoring in real time. Battery-operated CGM transmitters have yet to be formally tested and given safety approval for use in a hyperbaric environment. Materials and Methods: We evaluated and tested commercially available Dexcom. G6 CGM transmitters under hyperbaric conditions. Each transmitter contains a 3V, 130-mAh (0.39 Wh) lithium manganese dioxide battery (IEC CR1632) and circuit board that are fully encapsulated in epoxy. Each transmitter is pressurized to 90 pounds per square inch (psi) in an autoclave at 40ÅãC for up to 72 hours during manufacturing to ensure that all enclosed air spaces are eliminated from the epoxy. We compared the CGM components against section 14.2.9.3.17.5 of the 2018 National Fire Protection Association 99 (NFPA 99) Health Care Facilities Code requirements. Six CGM transmitters attached to estimated glucose value generators (EGVGs) underwent 11 pressurization cycles to 45 feet of seawater (fsw). All transmitters were returned to the manufacturer to assess post-exposure structural integrity. G6 sensors, which contain no electrical components or compressible air spaces, do not pose a risk in the hyperbaric environment. Results: There was no observed change in preset EGVG ..

Decompression sickness (DCS) occurs when nitrogen gas (N2) comes out of solution too quickly, forming bubbles in the blood and tissues. These bubbles can be a serious condition; thus it is of extreme interest in the dive community to model DCS risk. Diving models use tissue compartments to calculate tissue partial pressures, often using data obtained from other mammalian species (i.e., pigs). Adipose tissue is an important compartment in these models because N2 is five times more soluble in fat than in blood; at any blood/ tissue interface N2 will diffuse into the fat and can lead to bubble formation on ascent. Little is known about many characteristics of adipose tissue relevant to diving physiology. Therefore, we measured microvessel density and morphology, lipid composition, and N2 solubility in adipose tissue from humans and pigs. Human adipose tissue has significantly higher microvascular density (1.79 Å} 0.04 vs. 1.21 Å} 0.30%), vessel diameter (10.25 Å} 0.28 vs. 6.72 Å} 0.60 μm), total monounsaturated fatty acids (50.1 vs. 41.2 mol%) and N2 solubility (0.061 Å} 0.003 vs. 0.054 Å} 0.004 mL N2 mL-1 oil) compared to pig tissue. Pig adipose tissue has significantly higher lipid content (76.1 Å} 4.9 vs. 64.6 Å} ..