Dysbaric osteonecrosis (DON) among the artisanal diving fishermen of Yucatán, Mexico.

INTRODUCTION: Artisanal diving fishermen in Yucatán, Mexico have high rates of decompression sickness as a result of frequently unsafe diving practices with surface supplied compressed air. In this study, we investigated the prevalence of dysbaric osteonecrosis (DON), a type of avascular necrosis, in the most susceptible joints in a cohort of these fishermen. METHODS: We performed radiographs of bilateral shoulders, hips, and knees of 39 fishermen in Mexico and surveyed them about their medical and diving histories. We performed pairwise correlations to examine if the fishermen's diving behaviours affected the numbers of joints with DON. RESULTS: The radiographs revealed Grade II or higher DON in 30/39 (76.9%) of the fishermen. Twenty-two of 39 fishermen (56.4%) had at least two affected joints. The number of joints with DON positively correlates with the lifetime maximum diving depth and average bottom time. CONCLUSIONS: These findings represent among the highest prevalence rates of DON in divers and reflect the wide-spread scale of decompression sickness among these fishermen. Through this work, we hope to further educate the fishermen on the sequelae of their diving with the aim of improving their diving safety.

Time-Driven Activity-Based Costing Comparison of CT-Guided Versus MR-Guided SBRT.

PURPOSE: Magnetic resonance-guided radiation therapy (MRgRT) has recently become commercially available, offering the opportunity to accurately image and target moving tumors as compared with computed tomography-guided radiation therapy (CTgRT) systems. However, the costs of delivering care with these 2 modalities remain poorly described. With localized unresectable hepatocellular carcinoma as an example, we were able to use time-driven activity-based costing to determine the cost of treatment on linear accelerators with CTgRT compared with MRgRT. MATERIALS AND METHODS: Process maps, informed via interviews with departmental personnel, were created for each phase of the care cycle. Stereotactic body radiation therapy was delivered at 50 Gy in 5 fractions, either with CTgRT using fiducial placement, deep inspiration breath-hold (DIBH) with real-time position management, and volumetric-modulated arc therapy, or with MRgRT using real-time tumor gating, DIBH, and static-gantry intensity-modulated radiation therapy. RESULTS: Direct clinical costs were $7,306 for CTgRT and $8,622 for MRgRT comprising personnel costs ($3,752 v $3,603), space and equipment costs ($2,912 v $4,769), and materials costs ($642 v $250). Increased MRgRT costs may be mitigated by forgoing CT simulation ($322 saved) or shortening treatment to 3 fractions ($1,815 saved). Conversely, adaptive treatment with MRgRT would result in an increase in cost of $529 per adaptive treatment. CONCLUSION: MRgRT offers real-time image guidance, avoidance of fiducial placement, and ability to use adaptive treatments; however, it is 18% more expensive than CTgRT under baseline assumptions. Future studies that elucidate the magnitude of potential clinical benefits of MRgRT are warranted to clarify the value of using this technology.

Dysbaric osteonecrosis associated with decompression sickness in a fishing diver

Diving as a method of fishing is used worldwide in small-scale fisheries. However, one of the main causes of morbidity and mortality among fishermen is decompression sickness (DCS). We report the case of a 46-year-old male fisherman diver who presented with chronic inguinal pain that radiated to the lower left limb. Living and working in a fishing port in Yucatan, he had a prior history of DCS. A diagnosis of avascular necrosis in the left femoral head secondary to DCS was made via analysis of clinical and radiological findings. The necrosis was surgically resolved by a total hip arthroplasty. Dysbaric osteonecrosis is a more probable diagnosis. In this region fishermen undergo significant decompression stress in their daily fishing efforts. Further studies regarding prevalence of dysbaric osteonecrosis among small-scale fisheries divers are needed. In a community where DCS is endemic and has become an epidemic, as of late, the perception of this health risk remains low. Furthermore, training and decompression technique are lacking among the fishing communities.

Body mass index in association with decompression sickness events: cross-sectional study among small-scale fishermen-divers in southeast Mexico.

INTRODUCTION: Decompression sickness is endemic to small-scale fishermen-divers from coastal communities in southeast Mexico; overweight and obesity are also highly prevalent in the region. Existing literature suggests it is possible that fat tissue could play a role in decompression sickness pathophysiology. Our aim in this study is to describe the association between the number and severity of DCS events treated at the hyperbaric program and fishermen-diver body mass index. METHODS: In this cross-sectional study, we obtained anthropometric measurements of 105 fishermen-divers and reviewed clinical records of each participant at a hyperbaric program. RESULTS: Average BMI among participants was 34.5 ± 4.7, while 9.5% (n=10) were healthy-weighted, 28.6% (n=30) were overweight and 42.8% (n=65) were obese. Number of DCS events per diver was associated with BMI and severity of DCS in linear regression models. CONCLUSIONS: Overweight and obesity are highly preventable health problems; our results suggest that an association between these conditions and the frequency and the severity of DCS are an important topic to be further considered in longitudinal prospective studies.

Understanding dive behavior of artisanal fishermen divers of the Yucatán Peninsula.

INTRODUCTION/BACKGROUND: Artisanal fishermen dive for sustenance. The lifetime prevalence of decompression sickness (DCS) in this population is alarmingly high. We wanted to understand the level of decompression stress fishermen in this region of the Yucatán experience in their daily fishing effort. We used a mathematical model to quantify nitrogen-loading in a nine-tissue compartment model. MATERIALS AND METHODS: Approved by the UCLA IRB 2 #13-000532, this study was conducted during fishing seasons 2012 through 2017. Diving fishermen were instructed to attach dive recorders to their waists every fishing day during the study period. Sensus Ultra dive recorders (ReefNet Inc.), with an accuracy of ±1 foot of seawater (fsw), 0.304 meters, and an activation depth of 10 fsw, 3.04 meters, were used to record dive parameters. Sampling interval was set to 10 seconds. A program in RStudio was created to extract the dive profiles of each fishing day and curtail into single-line outputs: pressure, time, date, start of dive and end of dive. An exponential decay formula was used to calculate the nitrogen-loading pressures for nine theoretical tissue compartments. Final nitrogen pressure, controlling compartments, decompression stop and time at stop were calculated. RESULTS: Fishermen completed 4,961 dives over 1,758 diving days during the study period. The 40-minute compartment controlled most of the dives. The 80-minute compartment controlled 5%-20% of dives two through five. Decompression stop times for the last dive ranged from one minute to 190 minutes. Most of the required stop time observed was seen at depths of 1-15 fsw.

Efficacy of the U.S. Navy Treatment Tables in treating DCS in 103 recreational scuba divers.

Despite the fact that current decompression schedules reduce the risk of decompression sickness (DCS), recreational scuba divers continue to experience DCS. Therapy outcomes in these divers are difficult to track. Our study aims to understand the efficacy of the United States Navy (USN) Treatment Tables (5, 6, 6A, 9) in providing symptomatic relief among recreational scuba divers. We conducted a single-center retrospective review of recreational divers treated from 2003 to 2013. A total of 187 divers were identified: 84 divers were excluded, and the charts of the remaining 103 divers were independently reviewed by three clinicians. For these 103 divers, the response variable, therapy outcome, was categorized as no relief, partial relief, or complete relief of symptoms. In a population of 76 males and 27 females with an average of three dives and three treatments, 53 patients achieved complete symptomatic relief, 45 patients had partial relief, and five patients reported no relief at the end of all recompression treatments. Among the patients who achieved complete symptomatic relief, 28 (53%) needed only one recompression treatment. The depth of the diver's first dive and the change in symptoms within the first 20 minutes of the first recompression treatment were found to be explanatory variables of the treatment outcome.

Spinal decompression sickness in an artisanal diving fisherman in Yucatán, Mexico: a case report.

Artisanal fishermen around the world employ scuba and surface-supplied diving for their livelihoods and often undergo provocative dive profiles due to economic pressures. Consequently, rates of decompression sickness (DCS) are much greater than in recreational scuba divers. Here we present the case of a surface-supplied diving fisherman from the Yucatán Peninsula of Mexico, who suffered a significant episode of spinal DCS and underwent hyperbaric oxygen therapy treatments, with a favorable outcome. Additionally, we review the proposed mechanisms underlying spinal DCS.

Fatal cardiopulmonary decompression sickness in an untrained fisherman diver in Yucatán, Mexico: a clinical case report.

INTRODUCTION: In Yucatán, Mexico, during the sea cucumber season fishermen dive intensely to obtain good catches but are often at risk of decompression sickness (DCS). We present a single case fatality. OBJECTIVE: We analyzed the clinical course, medical assessment and recompression treatment plan of an untrained fisherman. CASE REPORT: A 35-year-old male ascended rapidly using compressed-air diving. Before reaching the coast, he reported dizziness, shortness of breath, and pain in the abdomen and legs. Three hours later, when symptoms worsened, he went to the hospital. He was admitted with increased osteotendinous reflexes and cutis marmorata in the abdomen. The patient was diagnosed with carbon monoxide (CO) poisoning and Type I DCS, receiving the U.S. Navy Treatment Table 5 (USN TT5). Before completing his treatment at depth, he developed myocardial infarction and died. The death certificate indicated Type I DCS, thrombotic pulmonary embolism and cardiac arrest. DISCUSSION: Upon reviewing his medical records, we uncovered no evidence to support the diagnosis of CO poisoning and thrombotic pulmonary embolism. The clinical presentation seems to be compatible with a serious decompression insult, not a Type I hit. Based on the information gathered, it seems likely that the patient died as a result of cardiopulmonary DCS. This case report suggests a need to provide fishermen divers in this region with formal dive training. There also seems to be a need to improve medical education for physicians who work at hyperbaric programs, and to ensure that sufficient and qualified staff is present to supervise patients inside the chambers.

Decompression sickness among diving fishermen in Mexico: observational retrospective analysis of DCS in three sea cucumber fishing seasons.

The probabilities of decompression sickness (DCS) among diving fishermen are higher than in any other group of divers. Diving behavior of artisanal fishermen has been directed mainly to target high-value species. The aim of this study was to learn about the occurrence of DCS derived from sea cucumber harvesting in the Yucatán Peninsula, Mexico. We conducted a retrospective chart review of diving fishermen treated at a multiplace hyperbaric chamber in Tizimín, Mexico. In total, 233 recompression therapies were rendered to 166 diving fishermen from 2014 to 2016. The average age was 36.7 ± 9.2 years (range: 20-59 years); 84.3% had experienced at least one DCS event previously. There was a correlation between age and DCS incidents (F: 8.3; R2: 0.07) and differences in the fishing depth between seasons (H: 9.99; p⟨0.05). Musculoskeletal pain was the most frequently reported symptom. Three divers, respectively, suffered permanent hearing loss, spinal cord injury and fatal outcome. Diving fishermen experience DCS at an alarmingly high rate, probably due to the type of species targeted, given the requirements in each case. Understanding divers' behaviors and their incentives while in pursuit of high-value species such as sea cucumber could help to find ways to mitigate health risks and help enforce regulation.

Hyperbaric programs in the United States: Locations and capabilities of treating decompression sickness, arterial gas embolisms, and acute carbon monoxide poisoning: survey results.

Hyperbaric oxygen therapy is the primary treatment for arterial gas embolism, decompression sickness and acute carbon monoxide poisoning. Though there has been a proliferation of hyperbaric centers throughout the United States, a scarcity of centers equipped to treat emergency indications makes transport of patients necessary. To locate and characterize hyperbaric chambers capable of treating emergency cases, a survey of centers throughout the entire United States was conducted. Using Google, Yahoo, HyperbaricLink and the UHMS directory, a database for United States chambers was created. Four researchers called clinicians from the database to administer the survey. All centers were contacted for response until four calls went unreturned or a center declined to be included. The survey assessed chamber readiness to respond to high-acuity patients, including staff availability, use of medical equipment such as ventilators and intravenous infusion devices, and responding yes to treating hyperbaric emergencies within a 12-month period. Only 43 (11.9%, N = 361) centers had equipment, intravenous infusion pumps and ventilators, and staff necessary to treat high-acuity patients. Considering that a primary purpose of hyperbaric oxygen therapy is the treatment of arterial gas embolism and decompression sickness, more hyperbaric centers nationwide should be able to accommodate these emergency cases quickly and safely.

Decreasing carbon monoxide in the diving air of artisanal fishermen in the Yucatán peninsula by separation of engine exhaust from compressor intake.

Artisanal fishermen in the Yucatán Peninsula utilize hookah dive systems (HDS). The air compressors in these HDS are not filtered, and the intake is near the engine exhaust. This proximity allows carbon monoxide (CO) from the exhaust to directly enter the HDS volume tank and contaminate the fishermen diver's air supply. Conservative safety standards permit a diver's air supply to contain 10 parts per million (ppm) of CO. This study quantified the levels of CO in the diver's air supply both before and after physical separation of the engine exhaust from the compressor intake. CO levels in seven volume tanks were analyzed before and after a 1-inch hose was attached to the compressor intake and elevated 5 feet above the engine exhaust. The tanks were drained and refilled before collecting each set of pre- and post-intervention gas samples. Four CO measurements were collected before and after the intervention from each volume tank. A C-Squared© CO Analyzer (± 1 ppm), calibrated with a Praxair 70 ppm CON2 gas (± 5%), was used to analyze the gas samples. A paired samples t-test shows a statistically significant difference in average CO values before and after the intervention (t = 6.8674, df: 27; p⟨0.0001). The physical separation of the engine exhaust from the compressor intake reduced the CO contamination of the diver air supply by 72%. This intervention could be applied to the hookah systems in the rest of the fishing cooperative to reduce the divers' risk of CO poisoning.

Diving behavior and fishing performance: the case of lobster artisanal fishermen of the Yucatan coast, Mexico.

An average of 209 cases of decompression sickness (DCS) have been reported every year among artisanal fishermen. divers of the Yucatan Peninsula, Mexico. DCS is a major problem among fishermen divers worldwide. This paper explores how diving behavior and fishing techniques among fishermen relate to the probability of experiencing DCS (Pdcs). Fieldwork was conducted in two communities during the 2012-2013 fishing season. Fishermen were classified into three groups (two per group) according to their fishing performance and followed during their journeys. Dive profiles were recorded using Sensus Ultra dive recorders (Reefet Inc.). Surveys were used to record fishing yields from cooperative and individual fishermen along with fishing techniques and dive behavior. 120 dives were recorded. Fishermen averaged three dives/day, with an average depth of 47 ± 2 feet of sea water (fsw) and an average total bottom time (TBT) of 95 ± 11 minutes. 24% of dives exceeded the 2008 U.S. Navy no-decompression limit. The average ascent rate was 20 fsw/minute, and 5% of those exceeded 40 fsw/minute. Inadequate decompression was observed in all fishermen. Fishermen are diving outside the safety limits of both military and recreational standards. Fishing techniques and dive behavior were important factors in Pdcs. Fishermen were reluctant to seek treatment, and symptoms were relieved with analgesics.

CO and CO2 analysis in the diving gas of the fishermen of the Yucatan Peninsula.

It is reported that more than 75% of 400 artisanal fisherman divers working off the Yucatan Peninsula experience decompression sickness (DCS) each year, making DCS an epidemic in this region. These divers use primitive hookah diving support systems (HDSS). Breathing air is supplied from inadequately filtered and poorly maintained gasoline-powered air compressors. We hypothesized that air supplies could be contaminated. Air contamination could produce symptoms consistent with some presentations of DCS. This could confound and falsely elevate the true incidence of DCS. A cross-sectional study was undertaken in a fishing community. Ten fishermen from a single cohort participated. Fishermen were instructed not to drain volume tanks following their last dive of the day before their diving air was sampled. Dräger carbon monoxide (CO) 5/a-P and carbon dioxide (CO2) 100/a Short-term Tubes were used to measure 1.0 liters (L) of gas through a Visi-Float flow meter at 0.2 L/minute. Average CO value was 42 ppm (8-150 ppm). Average CO2 was 663 ppm (600-800). Measurements exceeded recommended diving norms for CO of 20 ppm. CO2 exceeded one diving organization recommendation of 500 ppm. Separation of engine exhaust from compressor intake could decrease CO values in HDSS to acceptable standards thus eliminating one possible confounder from this DCS epidemic.

Association of microparticles and neutrophil activation with decompression sickness.

Decompression sickness (DCS) is a systemic disorder, assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles (MPs)--vesicular structures with diameters of 0.1-1.0 µm--have been implicated, but data in human divers have been lacking. We hypothesized that the number of blood-borne, Annexin V-positive MPs and neutrophil activation, assessed as surface MPO staining, would differ between self-contained underwater breathing-apparatus divers suffering from DCS vs. asymptomatic divers. Blood was analyzed from 280 divers who had been exposed to maximum depths from 7 to 105 meters; 185 were control/asymptomatic divers, and 90 were diagnosed with DCS. Elevations of MPs and neutrophil activation occurred in all divers but normalized within 24 h in those who were asymptomatic. MPs, bearing the following proteins: CD66b, CD41, CD31, CD142, CD235, and von Willebrand factor, were between 2.4- and 11.7-fold higher in blood from divers with DCS vs. asymptomatic divers, matched for time of sample acquisition, maximum diving depth, and breathing gas. Multiple logistic regression analysis documented significant associations (P < 0.001) between DCS and MPs and for neutrophil MPO staining. Effect estimates were not altered by gender, body mass index, use of nonsteroidal anti-inflammatory agents, or emergency oxygen treatment and were modestly influenced by divers' age, choice of breathing gas during diving, maximum diving depth, and whether repetitive diving had been performed. There were no significant associations between DCS and number of MPs without surface proteins listed above. We conclude that MP production and neutrophil activation exhibit strong associations with DCS.

Treatment of carbon monoxide poisoning with hyperbaric oxygen and therapeutic hypothermia.

We present a preliminary case report series of severe, acute carbon monoxide poisoning in which both hyperbaric oxygen (HBO2) and therapeutic hypothermia (TH) were used to ameliorate neurological sequelae. Carbon monoxide poisoning is a standard indication for HBO2. While typically used postcardiac arrest, TH has been used for other types of hypoxic-ischemic brain injury. Four patients were found comatose from carbon monoxide exposure. They were intubated and treated with high-flow oxygen before transfer to our hospital for HBO2. All received three HBO2 treatments and 24 hours of TH with a goal temperature of 33 degrees C utilizing the CoolGard 3000 Intravascular Temperature Management System. While in the HBO2 chamber, cooling was maintained with ice bags in the groin, axillae and under the head. Three of the four cases were discharged home with normal neurological exams. One patient sustained severe, diffuse brain injury yet made a dramatic neurological recovery with only minor limitations in higher order memory and attention. No patient left the hospital with other end organ damage including cardiac dysfunction. To our knowledge, these are the first reported cases of the use of both HBO2 and TH to treat severe, acute carbon monoxide poisoning.