Number 6

 [ Position Statement ] DOI: 10.22462/11.12.2017.14

 [ letter ] DOI: 10.22462/11.12.2017.13

Equalization of middle ear pressure is an important consideration for scuba divers. When middle ear pressure is asymmetric, a diver may experience alternobaric vertigo. Moreover, individuals with an underlying temporal bone dehiscence are predisposed to facial baroparesis. An understanding on behalf of fellow divers and emergency responders to recognize and differentiate facial baroparesis from decompression illness is critical. Misdiagnosis may lead to inappropriate treatment or unwarranted stoppage of diving. There have been a few dozen reported cases of facial baroparesis in the literature, but few have included firsthand accounts.  This report describes an incidence of unilateral facial baroparesis preceded by alternobaric vertigo, with commentary from divers who witnessed the individual experiencing the facial paresis. The facial weakness in this case resolved within 15 minutes after the diver chewed on fresh pineapple. This report suggests that alternobaric vertigo may be a harbingerof facial baroparesis. Upon resurfacing divers should consider prophylactic measures that help to dilate the Eustachian tube such as chewing, yawning and swallowing in order to minimize the risk of middle ear pressure-induced vertigo or facial paresis. DOI: 10.22462/11.12.2017.12

Background: Since 2016, the Naval Diving Unit (NDU) of the Republic of Singapore Navy (RSN) has instituted a smoking cessation trial program for their trainees, instituting a blanket ban on smoking during training hours in order to promote smoking cessation and create a smoke-free culture among its servicemen. For the rest of RSN personnel, they would attend a more costly, established Health Promotion Board (HPB) smoking cessation program, which employs social support strategies, while they undergo basic training in the Navy Military Experts Institute (NMI). Methodology: We examined the outcomes and direct costs of the NDU smoking cessation trial program, compared with the HPB smoking cessation program in NMI. The primary outcome was self-reported smoking cessation at the end of six months. Principal findings: The NDU smoking cessation program led to 50% reduction among smokers with no additional direct costs. It is comparable to a 59% reduction of smokers among trainees in the established HPB program, which costs US$1,955 per course in 2017. The results of both programs are not significantly different (χ2 = 0.34, P-value = 0.56). Neither program’s participants raised any nicotine withdrawal issues throughout. Conclusion: The results of the NDU smoking cessation program suggests that it is not inferior to the ..

Background: The influence of prolonged and repeated water immersions on heart rate variability (HRV) and complexity was examined in 10 U.S. Navy divers who completed six-hour resting dives on five consecutive days. Pre-dive and during-dive measures were recorded daily.  Methods: Dependent variables of interest were average heart rate (HR), time-domain measures of HRV [root mean square of successive differences of the normal RR (NN) interval (RMSSD), standard deviation of the NN interval (SDNN)], frequency-domain measures of HRV [low-frequency power spectral density (psd) (LFpsd), low-frequency normalized (LFnu), high-frequency psd (HFpsd), high-frequency normalized (HFnu), low-frequency/high-frequency ratio (LF/HF)], and non-linear dynamics of HRV  [approximate entropy (ApEn)]. A repeated-measures ANOVA was performed to examine pre-dive measure differences among baseline measures. Hierarchical linear modeling (HLM) was performed to test the effects of prolonged and repeated water immersion on the dependent variables.  Results: Pre-dive HR (P=0.005) and RMSSD (P<0.001) varied significantly with dive day while changes in SDNN approached significance (P=0.055). HLM indicated that HR decreased during daily dives (P=0.001), but increased across dive days (P=0.011); RMSSD increased during daily dives (P=0.018) but decreased across dive days (P<0.001); SDNN increased during daily dives (P<0.001); LF measures increased across dive days (LFpsd P<0.001; LFnu P<0.001), while HF measures decreased ..

This study aimed to assess the effect of extreme environmental exposure during an operational saturation dive on airway inflammation (exhaled nitric oxide (FeNo)), components of fitness (flexibility and aerobic capacity) and blood hematological variables. Six saturation divers, who undertook a 26 ± 0.5 day operational saturation dive were recruited to take part in this study. Participants completed a field-based repeated measure test battery on three occasions (pre-dive, post-dive and 24 hours after saturation dive). Hemoglobin concentration was significantly (P<0.001) reduced from pre- (15.3±0.8 g/dL) to post- saturation (14.25±1.2 g/dL) dive but recovered toward baseline values within 24 hours (15.13±1.03 g/dL; P=0.04).  Similarly, a reduction in plasma volume was observed in all participants from pre- to post-saturation dive trials. Airway inflammation response was non-significant, although a large inter-individual response was evident. Hip flexion, assessed by the sit and reach test did not change following the saturation dive. Data on aerobic capacity was collected in one participant only, due to practical difficulties in participant access.  In summary, this is the first investigation to conduct a multiple-component field-based study on operational saturation divers. The findings for this exploratory study present interesting groundings for further investigation.  DOI: 10.22462/11.12.2017.9

Rebreather diving has one of the highest fatality rates per man hour of any diving activity in the world. The leading cause of death is hypoxia, typically from equipment or procedural failures. Hypoxia causes very few symptoms prior to causing loss of consciousness. Additionally, since the electronics responsible for controlling oxygen levels in rebreathers often control their alarm systems, frequently divers do not receive any external warnings.  This study investigated the use of a forehead pulse oximeter as an independent warning device in the event of rebreather failure. Ten test subjects (seven male, three female, median age 29, range 26-35) exercised at a targeted rate of 2 L/minute oxygen consumption while on a non-functional rebreather breathing loop (mean consumption achieved 2.09 ± 0.36 L/minute).  Each subject was tested both at the surface and at pressurized depth of 77 fsw (starting pO2=0.7 atm). The data show that a pulse oximeter could be used to provide an Mk 16 rebreather diver with a minimum mean of 49 seconds (± 17 seconds SD) of warning time after a noticeable change in blood oxygen saturation (SpO2 ≤ 95%) but before any risk of loss of consciousness (calculated SpO2 ≤ 80%), so that the diver may take mitigating actions. No statistical difference ..

Objective: The aim of this study was to evaluate whether monitoring of acute carbon monoxide-poisoned (COP) patients by means of quantitative Romberg’s test (QR-test) during a hyperbaric oxygen (HBO2) therapy regimen could be a useful supplement in the evaluation of neurological status. Method: We conducted a retrospective study (2000-2014) in which we evaluated data containing quantitative sway measurements of acute COP patients (n = 58) treated in an HBO2 regimen. Each patient was tested using QR-test before and after each HBO2 treatment. Data were analyzed using linear mixed models (LMM). In each LMM, sway prior to HBO2 therapy was set as the fixed effect and change in sway after HBO2 therapy was set as the response variable. Patient, treatment number, weight and age were set as random effects for all LMMs. Results: From the LMMs we found that larger values of sway prior to HBO2 produced a negative change in sway. We found no correlation between CO level and sway (P=0.1028; P=0.8764; P=0.4749; P=0.5883). Results showed that loss of visual inputcaused a significant increase in mean sway (P=0.028) and sway velocity (P<0.0001). Conclusion: The Quantitative Romberg’s test is a fast, useful supplement to neurological evaluation and a potential valuable tool for monitoring postural stability during ..

Purpose: One of the most common complications of hyperbaric oxygen (HBO2) therapy is middle ear barotrauma (MEB), occasionally causing otalgia. The objective of this study was to evaluate the effect of dried salted plum consumption on MEB and otalgia associated with HBO2 therapy. Materials and methods: Patients undergoing the first chamber session of HBO2 therapy were included in the present prospective randomized controlled trial. The Valsalva maneuver was administered to all patients before HBO2. The patients were randomly divided into two groups: one that ate a dried salted plum during HBO2 treatment and the other that did not. An otoscopic examination was performed after HBO2 therapy. The MEB was graded according to Teed scores. The degree of otalgia was recorded using the Visual Analog Scale (VAS).  Results: Ninety patients were enrolled. The overall incidence of MEB (Teed score grade 1~4) was 39.6% (21 of 53) for patients administered a dried salted plum versus 37.8% (14 of 37) for the control group (P=1.000). The incidence of mild MEB (Teed score grade 1~2) and severe MEB (Teed score Grade 3~4) between the two groups was not significantly different. Otalgia was present in 5.7% (3 of 53) of patients administered a dried salted plum versus 18.9% (7 of 37) ..

Objectives: (1) To examine whether hyperbaric oxygen (HBO2) will inhibit growth of multidrug-resistant Klebsiella pneumoniae (MDR-K. pneumoniae) and extensively drug-resistant Klebsiella pneumoniae (XDR-K. pneumoniae); (2) To determine whether the effect of tigecycline on XDR-K. pneumoniae will be enhanced by HBO2.  Methods: The effects of 1.5 hours of treatment with normoxia (21% O2, 1 atmosphere absolute/ATA) or HBO2 (100% O2, 2 ATA) on bacterial counts of eight isolates of MDR-K. pneumoniae and eight isolates of XDRK. pneumoniae were studied. The effects of five hours of treatment with normoxia (21% O2, 1 ATA), tigecycline (21% O2, 1 ATA), HBO2 (100% O2, 3 ATA) or HBO2 + tigecycline (100% O2, 3 ATA) on proliferation of 10 isolates of XDR-K. pneumoniae were investigated.  Results: HBO2 at 100% O2, 2 ATA, 1.5 hours suppressed growth of MDR-K. pneumoniae but had no effect on XDR-K. pneumoniae. HBO2 at 100% O2, 3 ATA, five hours enhanced the effects of tigecycline on XDR-K. pneumoniae.  Conclusion: HBO2 in combination with or without tigecycline can be used to eliminate K. pneumoniae in vitro, and such treatment may be beneficial for patients with infections caused by K. pneumoniae. DOI: 10.22462/11.12.2017.5

Introduction: Necrotizing soft tissue infections (NSTI) are rare but potentially lethal disorders, and adequate management is time- and resource-demanding. This study aims to assess whether variations in the treatment modalities – surgery, hyperbaric oxygen (HBO2) therapy and negative pressure wound therapy – had an impact on the length to definitive source control in NSTI patients who underwent HBO2. Methods: This is a retrospective study of all NSTI patients treated with hyperbaric oxygen therapy between March 2007 and May 2015 at Unidade Local de Saúde de Matosinhos (ULSM) Hyperbaric Unit. A multiple linear regression model was used to assess the impact of different treatment modalities in the post-diagnosis time until source control. Results: 58 patients were included; overall mortality was 13.8%. Mean time until source control was 10.4 days (±5.4). All patients were under empiric and broad-spectrum antibiotics on the day of diagnosis. Patients underwent an average of 0.62 (±0.29) surgical interventions and 1.06 (±0.52) HBO2 sessions per day. The regression model (R2=0.86) showed that after adjusting for other covariates, doubling the number of HBO2 sessions per day shortened source control by five days (β= -5.25; 95% CI -6.49 to -4.01), and for each day that HBO2 was delayed, source control was achieved one day later (β ..

Objective: Hyperoxia is known to influence cardiovascular and endothelial function, but it is unknown if there are differences between younger and older persons. The aim of this study was to monitor changes in myocardial diastolic function and flow-mediated dilatation (FMD) in younger and elderly volunteers, before and after exposure to relevant hyperbaric hyperoxia. Methods: 51 male patients were separated into two groups for this study. Volunteers in Group 1 (n=28, mean age 26±6, “juniors”) and Group 2 (n=23, mean age 53±9, “seniors”) received standard HBO2 protocol (240kPa oxygen). Directly before and after hyperoxic exposure in a hyperbaric chamber we took blood samples (BNP, hs-troponin-t), assessed the FMD and echocardiographic parameters with focus on diastolic function. Results: After hyperoxia we observed a high significant decrease in heart rate and systolic/diastolic FMD. Diastolic function varied in both groups: E/A ratio showed a statistically significant increase in Group 1 and remained unchanged in Group 2. E/e’ ratio showed a slight but significant increase in Group 1, whereas e’/a’ ratio increased in both groups. Deceleration time increased significantly in all volunteers. Isovolumetric relaxation time remained unchanged and ejection fraction showed a decrease only in Group 2. There were no changes in levels of BNP and hs-troponin-t in either group. Conclusion: Hyperoxia seems to influence endothelial ..

Inadvertent exposure to radiation, chemical agents and biological factors are well recognized hazards associated with the health care delivery system. Less well appreciated yet no less harmful is risk of decompression sickness in those who accompany patients as inside attendants (IAs) during provision of hyperbaric oxygen therapy. Unlike the above hazards where avoidance is practiced, IA exposure to decompression sickness risk is unavoidable. While overall incidence is low, when calculated as number of cases over number of exposures or potential for a case during any given exposure, employee cumulative risk, defined here as number of cases over number of IAs, or risk that an IA may suffer a case, is not.  Commonly, this unique occupational environmental injury responds favorably to therapeutic recompression and a period of recuperation. There are, however, permanent and career-ending consequences, and at least two nurses have succumbed to their decompression insults.  The intent of this paper is to heighten awareness of hyperbaric attendant decompression sickness. It will serve as a review of reported cases and reconcile incidence against largely ignored individual worker risk. Mitigation strategies are summarized and an approach to more precisely identify risk factors that might prompt development of consensus screening standards is proposed. DOI: 10.22462/11.12.2017.2

Background: Femoral head necrosis (FHN) is a common invalidating disease with an unclear etiology and pathophysiology that affects middle-aged people. FHN may lead to joint collapse and require invasive treatments. Because of its clinical and socioeconomic significance, an early diagnosis, staging and appropriate treatment are required. Unfortunately, to date a unique algorithm for the treatment of FHN has not been defined. Objective: In this report we summarize the Tenth European Consensus Conference on hyperbaric medicine (April 2016, France), during which experts from Europe revised the list of accepted indications for hyperbaric oxygen (HBO2) treatment, including FHN. Methods: In this report all aspects of osteonecrosis discussed during the meeting have been considered: pathophysiology, clinical presentation, standard management, HBO2 therapy and evidence-based review of its efficacy. All observations are based on a thorough review of the best available research and evidence-based medicine. Conclusions: The Consensus Conference in Lille established FHN as an indication for HBO2 therapy and suggested a protocols guideline to adopt for this pathology. DOI: 10.22462/11.12.2017.1