Dive Medicine: Current Perspectives and Future Directions

Evolutionary genetics of pulmonary anatomical adaptations in deep-diving cetaceans

BACKGROUND

Cetaceans, having experienced prolonged adaptation to aquatic environments, have undergone evolutionary changes in their respiratory systems. This process of evolution has resulted in the emergence of distinctive phenotypic traits, notably the abundance of elastic fibers and thickened alveolar walls in their lungs, which may facilitate alveolar collapse during diving. This structure helps selective exchange of oxygen and carbon dioxide, while minimizing nitrogen exchange, thereby reducing the risk of DCS. Nevertheless, the scientific inquiry into the mechanisms through which these unique phenotypic characteristics govern the diving behavior of marine mammals, including cetaceans, remains unresolved.

RESULTS

This study entails an evolutionary analysis of 42 genes associated with pulmonary fibrosis across 45 mammalian species. Twenty-one genes in cetaceans exhibited accelerated evolution, featuring specific amino acid substitutions in 14 of them. Primarily linked to the development of the respiratory system and lung morphological construction, these genes play a crucial role. Moreover, among marine mammals, we identified eight genes undergoing positive selection, and the evolutionary rates of three genes significantly correlated with diving depth. Specifically, the SFTPC gene exhibited convergent amino acid substitutions. Through in vitro cellular experiments, we illustrated that convergent amino acid site mutations in SFTPC contribute positively to pulmonary fibrosis in marine mammals, and the presence of this phenotype can induce deep alveolar collapse during diving, thereby reducing the risk of DCS during diving.

CONCLUSIONS

The study unveils pivotal genetic signals in cetaceans and other marine mammals, arising through evolution. These genetic signals may influence lung characteristics in marine mammals and have been linked to a reduced risk of developing DCS. Moreover, the research serves as a valuable reference for delving deeper into human diving physiology.

Dive Hazards: Barotrauma, Flora, Fauna, Equipment, and Free Diving

ABSTRACT

Present-day diving comes in various forms, from utilizing sophisticated diving equipment to relying solely on one's ability to hold their breath. The diver and physician must be aware of the many common medical conditions and environmental considerations of this unique activity. While barotrauma remains the most common dive-related injury, injuries and accidents also are related to diving equipment-related accidents and exposure to marine flora and fauna. In addition, breath-hold diving, which includes free diving, snorkeling, and tasks, is an activity humans have done for thousands of years for recreation or survival. This article will update the dangers of diving and methods to prevent or treat injuries.

Travel Medicine

International travel can cause new illness or exacerbate existing conditions. Because primary care providers are frequent sources of health advice to travelers, they should be familiar with destination-specific disease risks, be knowledgeable about travel and routine vaccines, be prepared to prescribe chemoprophylaxis and self-treatment regimens, and be aware of travel medicine resources. Primary care providers should recognize travelers who would benefit from referral to a specialized travel clinic for evaluation. Those requiring yellow fever vaccination, immunocompromised hosts, pregnant persons, persons with multiple comorbid conditions, or travelers with complex itineraries may warrant specialty referral.

The effect of medical history and compressor on barotrauma

Background: Barotrauma causes damage to an enclosed cavity within the human body due to pressure changes inside and outside the body. This research aims to identify the effect of medical history and compressor on barotrauma.

Design and method: The case-control design and total sampling methods were used to obtained data from 174 respondents.

Results: The bivariate result showed that the value of medical history was at p=0.006, OR=2.47, with a compressor value of p=0.000, OR=16.29. Furthermore, the multivariate analysis indicated that the compressor has a dominant factor at OR=17.175.

Conclusions:: Both medical history and compressor affected barotrauma incidence, with compressor as the most dominant factor.

Middle ear barotrauma in diving

INTRODUCTION

Middle ear barotrauma (MEBt) is the most common medical complication in diving, posing a serious risk to dive safety. Given this prevalence and the continuing growth of the diving industry, a comprehensive overview of the condition is warranted.

METHODS

This was a survey study. An anonymous, electronic questionnaire was distributed to 7,060 recipients: professional divers of the Finnish Border Guard, the Finnish Rescue Services, and the Finnish Heritage agency; and recreational divers registered as members of the Finnish Divers' Association reachable by e-mail (roughly two-thirds of all members and recreational divers in Finland). Primary outcomes were self-reported prevalence, clinical characteristics, and health effects of MEBt while diving. Secondary outcomes were adjusted odds ratios (OR) for frequency of MEBt with respect to possible risk factors.

RESULTS

A total of 1,881 respondents participated in the study (response rate 27%). In total, 81% of the respondents had experienced MEBt while diving. Of those affected, 38% had used medications and 1% had undergone otorhinolaryngology-related surgical procedures due to MEBt. Factors most associated with MEBt were poor subjective success in Valsalva ('occasionally' versus 'always' successful: OR 11.56; 95% CI 7.24-18.47) and Toynbee ('occasionally' versus 'always' successful: OR 3.51; 95% CI 1.95-6.30) manoeuvres.

CONCLUSIONS

MEBt is common in both recreational and professional divers, having affected 81% of the respondents. The main possible risk factors include poor success in pressure equalisation manoeuvres.

Decompression sickness: a guide for emergency nurses

Decompression sickness (DCS) is commonly associated with diving or occupational exposure to compressed air, and is a life-threatening condition if left untreated. This article provides an overview of the pathophysiology and types of DCS. It also explains the principles of care for people presenting to the emergency department with DCS that emergency nurses must be familiar with, including the recognition of its signs and symptoms and the initial management required. It is important that emergency nurses are aware of the optimal treatment protocol for DCS, which involves its early recognition, prompt administration of high-flow oxygen and referral to the nearest hyperbaric chamber for recompression.