Short- and long-term effects of diving on pulmonary function

Determinants of Morbidities and Occupational Hazards among Scuba Divers in Andaman and Nicobar Islands, India

Background

Occupational health hazards pose significant risks in unique work environments such as scuba diving. This investigation aims to assess health profiles and occupational health determinants among scuba instructors in the Andaman and Nicobar Islands.

Materials and Methods

A cross-sectional survey was conducted among certified scuba instructors in the Andaman and Nicobar Islands during 2022-2023 by using a self-administered questionnaire. Data analysis was performed using SPSS version 25. Ethical approval was granted by the institutional ethical committee.

Results

The study population comprised 423 male instructors with a mean age of 26.24 ± 4.71 years. They averaged 9 ± 5.2 years of diving experience and 4 ± 3.86 years as instructors. Physical injury underwater was the most prevalent hazard, experienced by 10.4% of participants. There was a positive correlation between the instructors' knowledge of health and safety and their years of experience.

Conclusion

The scuba instructors displayed elevated levels of anxiety and depression, likely due to the high risks associated with their job.

The effects of underwater diving on the lung function of divers in coastal areas of tourism destinations: A cross-sectional study in North Sulawesi Province, Indonesia

North Sulawesi is renowned for its captivating underwater tourism, attracting SCUBA divers and traditional divers. Given the potential impact of diving activities on lung function, this study aims to explore differences in lung function among self-contained breathing apparatus (SCUBA) diving tourism workers, traditional divers utilizing breathing air compressors and air lines, and non-divers within the coastal areas of tourism destinations in North Sulawesi. Employing a descriptive comparative study with a cross-sectional approach, 90 subjects were categorized into three groups, and selected through simple random sampling. Spirometry was utilized for data collection, and Analysis of Variance (ANOVA) was employed for comparisons, with post hoc analysis for specific differences. The ANOVA analysis revealed significant variations in FVC Predicted, FVC Measured, FEV1, and obstruction and restriction values among SCUBA divers, traditional divers, and non-divers with a level of significance of p < 0.05. Post hoc analysis exhibited noteworthy distinctions in FVC Predicted, FVC Measured, and FEV1 between traditional divers and non-divers, and between SCUBA divers and traditional divers (p < 0.00). Obstruction values showed differences between SCUBA divers and traditional divers (p = 0.012), while restriction values indicated disparities between traditional divers and non-divers (p = 0.019). In conclusion, there were significant variations in lung function among SCUBA diving tourism workers, traditional divers using compressors and air lines, and non-divers within the coastal areas of tourism destinations in North Sulawesi.

Does Decreased Diffusing Capacity of the Lungs for Carbon Monoxide Constitute a Risk of Decompression Sickness in Occupational Divers?

Long-term alterations of pulmonary function (mainly decreased airway conductance and capacity of the lungs to diffuse carbon monoxide (DLCO)) have been described after hyperbaric exposures. However, whether these alterations convey a higher risk for divers' safety has never been investigated before. The purpose of the present pilot study was to assess whether decreased DLCO is associated with modifications of the physiological response to diving. In this case-control observational study, 15 "fit-to-dive" occupational divers were split into two groups according to their DLCO measurements compared to references values, either normal (control) or reduced (DLCO group). After a standardized 20 m/40 min dive in a sea water pool, the peak-flow, vascular gas emboli (VGE) grade, micro-circulatory reactivity, inflammatory biomarkers, thrombotic factors, and plasmatic aldosterone concentration were assessed at different times post-dive. Although VGE were recorded in all divers, no cases of decompression sickness (DCS) occurred. Compared to the control, the latency to VGE peak was increased in the DLCO group (60 vs. 30 min) along with a higher maximal VGE grade (p < 0.0001). P-selectin was higher in the DLCO group, both pre- and post-dive. The plasmatic aldosterone concentration was significantly decreased in the control group (-30.4 ± 24.6%) but not in the DLCO group. Apart from a state of hypocoagulability in all divers, other measured parameters remained unchanged. Our results suggest that divers with decreased DLCO might have a higher risk of DCS. Further studies are required to confirm these preliminary results.

Pulmonary oxygen toxicity in occupational diving

One of the hazards of occupational diving is pulmonary oxygen toxicity, which can lead to reduced lung diffusion capacity and fibrosis. The current gold standard to determine the ‘safe limits’ for oxygen was developed more than 50 years ago and lacks the accuracy required for occupational specialists. These restrictions may be overcome by new diagnostic methods like exhaled breath analysis, which would allow occupational specialists to accurately monitor pulmonary health in the individual diver, and thus reduce long-term health effects of professional diving.

Pulmonary Effects of One Week of Repeated Recreational Closed-Circuit Rebreather Dives in Cold Water

Background and Objectives: The use of closed-circuit rebreathers (CCRs) in recreational diving is gaining interest. However, data regarding its physiological effects are still scarce. Immersion, cold water, hyperoxia, exercise or the equipment itself could challenge the cardiopulmonary system. The purpose of this study was to examine the impact of CCR diving on lung function and autonomous cardiac activity after a series of CCR dives in cold water. Materials and Methods: Eight CCR divers performed a diving trip (one week) in the Baltic Sea. Spirometry parameters, SpO₂, and the lung ultrasonography score (LUS) associated with hydration monitoring by bioelectrical impedance were assessed at the end of the week. Heart rate variability (HRV) was recorded during the dives. Results: No diver declared pulmonary symptoms. The LUS increased after dives combined with a slight non-pathological decrease in SpO₂. Spirometry was not altered, and all body water compartments were increased. Global HRV decreased during diving with a predominant increase in sympathetic tone while the parasympathetic tone decreased. All parameters returned to baseline 24 h after the last dive. Conclusions: The lung aeration disorders observed seem to be transient and not associated with functional spirometry alteration. The HRV dynamics highlighted physiological constraints during the dive as well as environmental-stress-related stimulation that may influence pulmonary changes. The impact of these impairments is unknown but should be taken into account, especially when considering long and repetitive CCR dives.

Lung function changes in divers after a single deep helium-oxygen dive

INTRODUCTION

This study measured pulmonary function in divers after a single helium-oxygen (heliox) dive to 80, 100, or 120 metres of sea water (msw).

METHODS

A total of 26 divers participated, of whom 15, five, and six performed a 80, 100, or 120 msw dive, respectively. While immersed, the divers breathed heliox and air, then oxygen during surface decompression in a hyperbaric chamber. Pulmonary function was measured twice before diving, 30 min after diving, and 24 h after diving.

RESULTS

At 30 min after the 80 msw dive the forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratio and the maximum expiratory flow at 25% of vital capacity (MEF₂₅) values decreased (89.2% to 87.1% and 2.57 L·s⁻¹ to 2.35 L·s⁻¹, P = 0.04, P = 0.048 respectively) but FEV₁/FVC returned to the baseline values by 24 h post-dive. Other pulmonary indicators exhibited downward trends at 30 min after the dive, but statistical significance was lacking. Interestingly, though several parameters decreased after the 100 msw dive, statistical significance was not reached. After the 120 msw dive, the FEV₁/FVC and MEF₇₅ decreased (90.4% to 85.6% and 8.05 L·s⁻¹ to 7.46 L·s⁻¹, P = 0.01, P = 0.007). The relatively small numbers of subjects who dived to 100 and 120 msw depths may explain the inconsistent results. The subjects diving to 100 and 120 msw were more trained / skilled, but this would not explain the inconsistencies in results between these depths.

CONCLUSIONS

We conclude that single deep heliox dives cause a temporary decrease in FEV₁/FEV and MEF25 or MEF₇₅, but these changes can recover at 24 h after the dive.

Effect of a Single Simulated 500 m Saturation Dive on Lung Function

Background: Whether deep saturation diving causes injury to lung function remains controversial and the mechanism is unclear. The present study aimed to evaluate the effects of a 500 m simulated single saturation dive on lung function.

Methods: A retrospective study was performed in nine professional divers who spent 176 h in a high-pressure environment simulating a depth of 500-m saturation dive (51 atm, 5.02 Mpa). Pulmonary function parameters were investigated and compared before and on 3 days after the dive.

Results: Nine professional divers aged (36 ± 7) years were enrolled. Three days after the dive, the parameters related to expiratory flow (forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC)) were decreased; the parameters related to small airway function (forced expiratory flow at 50%, 75% of FVC exhaled and forced mid-expiratory flow) were decreased compared with those before the dive (both p < 0.05). Additionally, after the dive, the parameters related to pulmonary diffusion function were decreased compared with those before the dive (both p < 0.05). The parameters related to lung volume (residual volume, vital capacity and total lung volume) and those related to respiratory exertion (peak expiratory flow and forced expiratory flow at 75% of FVC exhaled) were not significantly different between after and before the dive. Two divers with small airway dysfunction before the dive had obstructive ventilatory dysfunction after the dive. Additionally, mild obstructive ventilatory dysfunction in three divers before the dive became severe after the dive. After a bronchial dilation test, five divers showed improvement of FEV₁, which ranged from 0.10 to 0.55 L. Chest radiographs and echocardiography of all divers were normal after diving.

Conclusion: 500 m simulated saturation diving induces a decrease in small airway function and diffusion function. This injury may be associated with small airway and diffusion membrane lesions.

Lung Function in Traditional Shellfish Divers in Southern Chile-A Cross-Sectional Study

The long-term effects of diving on human lung function are controversially discussed. We investigated the lung function of traditional shellfish divers in southern Chile and identified risk factors for reduced lung volumes in divers. In a cross-sectional study, we assessed lung function in traditional shellfish divers and fishermen from two fishing communities. Male divers and fishermen aged 18–60 years were recruited. Participants’ health and diving habits were assessed via standardized questionnaires. Descriptive statistics, chi-squared tests and multiple linear regression models were applied. Through door-to-door sampling, we recruited 112 divers and 63 fishermen (response 67%). Valid spirometries were obtained from 98 divers and 52 fishermen. Divers had higher values of forced vital capacity (FVC, Beta = 0.28, 95% confidence interval (CI): 0.09; 0.47) and forced expiratory volume in 1 s (FEV1, Beta = 0.23, 95%-CI: 0.07; 0.39) compared to fishermen. Among divers, lower values of FVC (Beta = −0.35, 95%-CI: −0.65; −0.05) were found in those with a high diving frequency, while diving depth was associated with higher values of FVC (Beta = 0.28, 95%-CI = 0.04; 0.52). Professional divers had better lung function compared to fishermen. However, among divers, lung function decreased with cumulative diving exposure, warranting approval in future studies to ensure the safety and health of divers.

Oral seeding and niche-adaptation of middle ear biofilms in health

The entrenched dogma of a sterile middle ear mucosa in health is incongruent with its periodic aeration and seeding with saliva aerosols. To test this, we sequenced 16S rRNA-V4 amplicons from otic secretions collected at the nasopharyngeal orifice of the tympanic tube and, as controls, oropharyngeal and buccal samples. The otic samples harbored a rich diversity of oral keystone genera and similar functional traits but were enriched in anaerobic genera in the Bacteroidetes (Prevotella and Alloprevotella), Fusobacteria (Fusobacterium and Leptotrichia) and Firmicutes (Veillonella) phyla. Facultative anaerobes in the Streptococcus genus were also abundant in the otic and oral samples but corresponded to distinct, and sometimes novel, cultivars, consistent with the ecological diversification of the oral migrants once in the middle ear microenvironment. Neutral community models also predicted a large contribution of oral dispersal to the otic communities and the positive selection of taxa better adapted to growth and reproduction under limited aeration. These results challenge the traditional view of a sterile middle ear in health and highlight hitherto unknown roles for oral dispersal and episodic ventilation in seeding and diversifying otic biofilms.

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The middle ear mucosa harbors a rich bacterial community in health.

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Oral migration is the primary mechanism for seeding otic biofilms.

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Periodic aeration of the middle ear enriches for anaerobic taxa and promotes the ecological diversification of oral migrants.

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Our study challenges the entrenched dogma of a sterile middle ear in health.

Is it safe to SCUBA dive with asthma?

Introduction: Internationally it is estimated that six million people participate in self-contained underwater breathing apparatus (SCUBA) diving each year. Registries suggest a significant proportion of divers have a current or historical diagnosis of asthma. Previously individuals with asthma were prohibited from diving, however, several contemporary guidelines suggest a select population of patients with asthma may be able to dive with an acceptable degree of risk. Areas covered: Divers with asthma may be at an increased risk of a variety of diving-related medical injuries including; pulmonary barotrauma (PBT), pneumothorax, pneumomediastinum, arterial gas embolism (AGE), reduction in pulmonary function, bronchospasm and decompression sickness (DCS). This article will discuss the latest evidence on the incidence of adverse events in diving with a focus on those caused by asthma. Expert opinion: Physicians can be faced with the difficult task of counseling patients with asthma who wish to dive. This review article will aim to explore the current guidelines which can assist a physician in providing a comprehensive dive safety assessment.

Environmental Exposures and Asthma in Active Duty Service Members

PURPOSE OF REVIEW

Reports of respiratory symptoms, including asthma and hyper-reactive airway disease, have been more numerous in the media and medical literature since active duty service members (SM) began to support campaigns in South West Asia (SWA). Numerous environmental exposures have been reported and this review assesses the available evidence surrounding exposures, confounding conditions, and attempts to develop screening mechanisms.

RECENT FINDINGS

While particulate matter exposures and particularly exposure to burn pits have garnered much attention, a 2010 Armed Forces Health Surveillance Center report and 2011 Institute of Medicine publication did not identify a link between exposure to particulate matter with SM respiratory disease. The "Study of Active Duty Military for Pulmonary Disease related to Environmental Deployment Exposure," (STAMPEDE) and STAMPEDE II have not identified effective forms of routine screening and these and other sources point to the importance of other factors in SM respiratory disease. These include higher than anticipated rates of tobacco use in deployed settings, impacts of obesity, recurrence of childhood asthma, and of confounding conditions such as Paradoxical Vocal Fold Motion. As with the general population, a complex set of clinical inputs and environmental exposures surround asthma and similar respiratory processes in SM. Concrete relationships and mechanisms for assessment continue to be assessed and refined, but clear associations and pathways have remained elusive.

The impact of health on professional diver attrition

INTRODUCTION

Approximately 77% of professional divers leave the industry within five years of entry, for reasons that are uncertain. One possibility is that attrition is due to ill-health. The health of New Zealand occupational divers is surveyed by a comprehensive medical examination every five years and by a health questionnaire in the intervening years. Divers are thereby confirmed 'fit' annually. The aim of this study was to determine if divers quit the industry due to a health problem not identified by this health surveillance system.

METHOD

601 divers who had left the industry within five years of entry medical examination ('quitters') were identified from a computerised database. One hundred and thirty-six who could be contacted were questioned about their principal reason for quitting. Comparison was made between the health data of all those defined as 'quitters' and a group of 436 'stayers' who have remained active in the industry for over 10 years.

RESULTS

Health was the principal reason for abandoning a diving career for only 2.9% of quitters. The overwhelming majority (97.1%) quit because of dissatisfaction with aspects of the work, such as remuneration and reliability of employment. Besides gender, the only significant difference between the health data of quitters and stayers was that smoking was four times more prevalent among quitters.

CONCLUSIONS

The key determinant of early attrition from the New Zealand professional diver workforce is industry-related rather than health-related. The current New Zealand diver health surveillance system detects the medical problems that cause divers to quit the industry.

Long-term changes in spirometry in occupational divers: a 10-25 year audit

AIM

To determine whether long-term engagement in occupational diving causes significant changes in spirometric measurements.

METHOD

All divers with adequate spirometric records spanning at least 10 years were identified from the New Zealand occupational diver database. Changes in lung function over time were compared with normative values derived using published prediction equations. Any significant changes were tested for correlation with age, duration of occupational diving, gender, smoking history and body mass index (BMI).

RESULTS

Spirometry data spanning periods of 10 to 25 years were analysed for 232 divers. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) declined with increasing duration of diving, but slightly less than predicted with increasing age, while peak expiratory flow (PEF) declined more than expected for age in longer-term divers. The changes in PEF were statistically significant, and correlated with duration of diving exposure, initial age and final BMI. Nevertheless, the changes were small and probably clinically insignificant.

CONCLUSION

We compared changes in spirometric parameters over long periods of occupational diving with normative data and found no clinically significant differences that could be attributed to diving. We found no justification for routine spirometry in asymptomatic divers.