Number 2

The previous DAN Annual Diving Report was the 2012-2015 edition that analyzed data over a four-year period from 2010-2013. Similar to the previous edition, this report is composed of four main sections: Diving Fatalities, Diving Injuries, the Diving Incident Reporting System and Breath-hold Diving Incidents. Each segment presents data and includes summaries and vignettes of pertinent cases to better understand why and how injuries occur. DOI: 10.22462/3.4.2017.14

Background: Dog bites are a frequent injury, but the incidence and type of lesions vary across countries. Although only few patients develop complications, the treatment of advanced injuries has a considerable medical, social and economic impact. A frequently isolated pathogen in dog bite wounds is Capnocytophaga canimorsus, a bacterium that can cause sepsis or meningitis. Hyperbaric oxygen (HBO2) therapy has been shown to be useful in treating anaerobic infections, most likely because it creates an inhospitable environment for the bacterium and enhances the patient’s immune response.  Aim: We present a case series of C. canimorsus infections treated with HBO2 in adjunction to antibiotic therapy. Furthermore, we tested the in vitro activity of ceftaroline against C. canimorsus, alone and in association with hyperbaric oxygen therapy. Methods: We included nine (9) patients admitted to surgery department of “A. Cardarelli” Hospital (Naples) after dog bite, from 2010 to 2016. All were initially treated with antibiotics and required transfer to the intensive care unit due to worsening conditions. C. canimorsus was isolated from wounds, and HBO2 therapy was administered in adjunction to antibiotics, until clinical improvement and microbiological test negativity. We tested the activity of hyperbaric oxygen therapy in adjunction to ceftaroline on cultured plates with C. canimorsus ..

Introduction: The carboxyhemoglobin half-life (COHb t1/2) during hyperbaric oxygen (HBO2) is often quoted as 23 minutes, derived from the average of two adult male volunteers breathing HBO2 at 3 atmospheres absolute (ATA). However, the mean COHb t1/2 of 12 male volunteer smokers was 26.3 minutes at 1.58 ATA and in 12 non-intubated carbon monoxide (CO)-poisoned patients treated at 3 ATA, was 43 minutes. Case report: An 81-year old male, poisoned by an improperly ventilated natural gas heater, was intubated for coma, then treated with HBO2. His PaO2/FiO2 = 283 from aspiration. His initial COHb was 34.4%, and 18 minutes before HBO2, 5.9%. After a compression interval of 17 minutes, the COHb measured after 22 minutes at 3 ATA was 3.3%. Results: By exponential decay, his COHb t1/2 before HBO2 was 95 minutes. We estimate the range for COHb t1/2 during compression as 62-81 minutes and for the 3 ATA interval, 58 to 49 minutes, respectively. The mid-point estimate of COHb t1/2 at 3 ATA was 53 minutes. Conclusions: The COHb t1/2 we calculated is greater than previously reported, but longer in our patient possibly because of concomitant respiratory failure, lung dysfunction, and mechanical ventilation. The often-cited COHb t1/2 of 23 minutes, likely underestimates the actual COHb t1/2 in CO-poisoned patients, ..

We report the case of a 54-year-old male compressed- air worker with gas bubbles detected by computed tomography (CT). He had complained of strong abdominal pain 30 minutes after decompression after working at a pressure equivalent to 17 meters of sea water for three hours. The initial CT images revealed gas bubbles in the intrahepatic portal vein, pulmonary artery and bilateral femoral vein. After the first hyperbaric oxygen treatment (HBO2 at 2.5 atmospheres absolute/ATA for 150 minutes), no bubbles were detected on repeat CT examination. The patient still exhibited abdominal distension, mild hypesthesia and slight muscle weakness in the upper extremities. Two sessions of U.S. Navy Treatment Table 6 (TT6) were performed on Days 6 and 7 after onset. The patient recovered completely on Day 7.  This report describes the important role of CT imaging in evaluating intravascular gas bubbles as well as eliminating the diagnosis of other conditions when divers or compressed-air workers experience uncommon symptoms of decompression illness. In addition, a short treatment table of HBO2 using non-TT6 HBO2 treatment may be useful to reduce gas bubbles and the severity of decompression illness in emergent cases. DOI: 10.22462/3.4.2017.11

Facial nerve palsy can occur from inflammatory, infectious, ischemic, neoplastic, traumatic, idiopathic and dysbaric causes. We present a case of right-sided facial paralysis after scuba diving in an otherwise healthy, 37-year-old experienced female diver. She completed several dives breathing nitrox over six days, with no difficulties. Thirty-five (35) hours after the last dive she flew by commercial aircraft home and reported that she felt normal. Within 48 hours she developed right-sided facial paralysis, in the absence of viral prodrome. Thorough evaluation by emergency medicine and neurology ruled out stroke. She sought hyperbaric medicine consultation, and we suspected idiopathic facial nerve paresis, or Bell’s palsy. Treatment with steroids was initiated and led to a quick and full recovery. With symptom onset soon after diving and flying, this case highlights the importance of considering dysbaric and non-dysbaric diagnoses in divers, while understanding disorders that can mimic decompression sickness.  DOI: 10.22462/3.4.2017.10

Diabetic foot ulcers may result in loss of an extremity and may even lead to mortality. The use of comprehensive foot care programs which include early screening and evaluation of problems, foot care education, preventive therapy and referral to specialists has been shown to reduce amputation rates by 49-85.  A 51-year-old woman with Type 2 diabetes under surveillance for nine months was referred from the emergency department. She presented with an entirely inflamed right foot with ulcer covering two-thirds proximal of the foot for 30 days’ duration. There was extensive edema as well as cellulitis extending to the knee, fluctuating abscesses and lymphangitis to the ankle. Magnetic resonance imaging showed extensive abscesses and edema in foot compartments. After a further four weeks of antibiotics, 80 sessions of hyperbaric oxygen therapy shrank the wound from 15x15x2 cm to 3x3x0.2 cm. The wound was closed with a split thickness graft, and healing completed four months after presentation. Patients with diabetic foot deserve clinical evaluations of the whole body rather than a regional treatment. An interdisciplinary approach involving both medical and surgical treatment options should be conducted according to this perspective. It could be effective in lowering major amputation rates and even preventing amputations. Simultaneously administered effective debridement methods, utilization of minor ..

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. DOI: 10.22462/3.4.2017.8

A neoprene wetsuit is widely used to reduce thermal dispersion during diving. Recent observations have pointed out that elastic recoil of the wetsuit might have significant compressive effects, able to affect water and electrolyte homeostasis during both dry and immersed conditions. The aim of this study was to evaluate the possible cardiovascular and respiratory effects of the neoprene wetsuit in dry conditions in a sample of experienced divers. Twenty-four (24) healthy divers were evaluated by Doppler-echocardiography and by spirometry in basal conditions and while wearing a full neoprene wetsuit. During wetsuit conditions, we observed a significant decrease in heart rate (-5%; p<0.05) and cardiac output (-12%; p<0.05), and a significant increase in total peripheral resistances (15%; p<0.05). Moreover, a significant reduction of right ventricular early diastolic filling was observed (-15%; p<0.05). As concerns pulmonary function, a significant reduction of vital capacity (-2%; p<0.001) and expiratory reserve volume (-25%; p<0.001), and a significant increase of inspiratory capacity (9%; p<0.001) and tidal volume (25%; p<0.05) were observed. These data support the hypothesis that neoprene elastic recoil, possibly due to a compression exerted on chest, might affect systemic circulation (decreasing cardiac output and impairing right ventricular filling) and respiratory function. DOI: 10.22462/3.4.2017.7

Hypertension is one of the most common chronic diseases in the world: in the United States, it affects one-third of the adult population. Most cases are primary hypertension – with no identified cause – and significantly increase risk for cardiovascular disease and stroke. At NASA’s Neutral Buoyancy Laboratory (NBL), there is a cadre of professional divers who provide underwater support during extravehicular activity training (EVAs, commonly referred to as “spacewalks”) for astronauts. The NBL occupational health program requires regular “work-site” physical exams, including blood pressure checks, on at least a weekly basis. Although some blood pressures measured during such regular checks were elevated, the diagnosis and management of blood pressure was outside the scope of that occupational medicine program. As a result, there was no protocol to analyze and manage asymptomatic elevated blood pressure if and when it warranted physician follow-up. We therefore analyzed the blood pressure data from all divers in 2015, vetted the worksite physical and developed a referral pathway to ensure divers have access to effective management of their blood pressure while minimizing impact of such a program on daily operations. DOI: 10.22462/3.4.2017.6

Introduction: Acute carbon monoxide (CO) poisoning causes serious health problems such as neuropsychological sequelae. This study aimed to investigate neuronal apoptosis and the effects of hyperbaric oxygen (HBO2) on different regions of the rat hippocampus after CO poisoning.  Methods: 90 mature male Sprague Dawley rats were randomly divided into three groups: the normal control group (NC group), the acute carbon monoxide-poisoned group (CO group) and the hyperbaric oxygen treatment group (HBO2 group). CO exposure included 0, 1, 3, 7, 14 and 21 treatment days, one exposure on the first day, and sacrifice on each of the following days. HBO2 exposure included treatment for 0, 1, 3, 7, 14 and 21 days, daily treatment after CO exposure, and sacrifice after the last HBO2 treatment on each of those days. Hematoxylin-eosin staining, immunohistochemical staining, immunofluorescence staining, and western blot analysis were performed to detect apoptosis in brain tissue samples.  Results: MMP-9 and caspase-3 were prominently increased by CO exposure and inhibited by HBO2 in the CA3 region in the hippocampus at one, three and seven days (immunohistochemical staining [IHC]: P < 0.05). Neu N and the ratio of Bcl-2/ BAX were prominently decreased by CO exposure and rescued by HBO2 in the CA3 region after seven days of treatment (IHC: P < 0.05). Conclusion: These findings ..

Background: Decompression sickness (DCS) induced by fast buoyancy ascent escape (FBAE) is a special DCS, characterized with cardiopulmonary injuries. Serum metabonomics of this type of DCS has not yet been studied. We proposed a metabonomics approach for assessing serum metabonomics changes and evaluating the preventive effect of pyrrolidine dithiocarbamic acid (PDTC) in FBAE-induced DCS rats. Method: Sixty-five (65) rats were divided into three groups, including the Control, DCS and PDTC groups. After receiving physiological saline or PDTC pretreatment, rats in the DCS and PDTC groups received the same protocol of simulated FBAE. Following this, a metabonomics approach – combined with pattern recognition methods including PCA and PLS-DA – was used to characterize the global serum metabolic profile on survival rats (five rats per group) associated with abnormal FBAE-induced DCS. As the VIP-value threshold cutoff of the metabolites was set to 2, metabolites above this threshold were filtered out as potential target biomarkers. Result: Sixteen (16) distinct potential biomarkers in rat plasma were identified. PDTC significantly lowered DSC mortality from 60% to 10%, and alleviated ultra-structural alteration of the left ventricular apex compared to the DCS group. It was found that abnormal FBAE-induced DCS was closely related to disturbed fatty acid metabolism, ..

Context: Middle ear barotrauma (MEB) is common during chamber compression in hyperbaric oxygen therapy. However, little evidence exists on an optimal compression protocol to minimize the incidence and severity of MEB. Objective: To compare the incidence of MEB during hyperbaric oxygen therapy using two different chamber compression protocols. Design: Double-blinded, randomized controlled trial. Setting: Hyperbaric Medicine Unit, The Townsville Hospital, Queensland, Australia, September 2012 to December 2014. Patients: 100 participants undergoing their first hyperbaric oxygen therapy session. Intervention: Random assignment to a staged (n=50) or a linear (n=50) compression protocols. Photographs of tympanic membranes were taken pre- and post-treatment and then graded. Middle ear barotrauma was defined as an increase of at least one grade on a modified TEED scale. Results: The observed MEB incidence under the staged protocol was 48% compared to 62% using the linear protocol (P=0.12, exact one-sided binomial test), and thus the staged protocol did not show a significant improvement in MEB. However, the staged protocol resulted in significantly less severe deteriorations in MEB grades when compared to the linear protocol (P=0.028, exact one-sided Mann-Whitney type test).  Conclusion: The use of the assessed staged compression protocol for the first hyperbaric oxygen treatment showed no significant effect on the overall incidence of MEB when compared to ..

Introduction: Hyperbaric oxygen (HBO2) therapy is generally safe and well tolerated. However, known side effects do exist. Elevation in the blood pressure of patients undergoing HBO2 therapy is a less defined potential side effect. We sought to better quantify effects of HBO2 on blood pressure (BP) in patients undergoing HBO2. Methods: A retrospective chart review was performed on quality assurance data captured on all patients undergoing HBO2 between March 2012 and October 2015 at a large tertiary referral university hospital hyperbaric center. Results: We identified 155 patients who received 3,147 hyperbaric oxygen treatments. For all treatments there was an overall increase in the median systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) following treatment (Table 2). No statistically significant difference was found when comparing patients with and without hypertension. Calcium channel blockers (CCB) and beta-blockers (BB) were found to have an agonizing effect while ACE inhibitors (ACEI) were found to have a protective effect (Table 4). The change in SBP was less with each additional treatment in patients undergoing more than one treatment. Discussion: The current study demonstrates that absolute rises in blood pressure do occur as a result of HBO2 therapy. However, the extent of this effect is not ..

The American College of Emergency Physicians (ACEP) recently published its official policy on the evaluation and management of patients with acute carbon monoxide (CO) poisoning [1], an update of the policy previously published in 2008. Three questions regarding CO poisoning were posed to a 30-person ACEP subcommittee, which employed a comprehensive literature review to attempt to draw conclusions. While this is a major step forward, we feel that their conclusions warrant comment. DOI: 10.22462/3.4.2017.1