Experienced Divers Research Articles

Successive deep dives impair endothelial function and enhance oxidative stress in man

The aim of this study was to assess the effects of successive deep dives on endothelial function of large conduit arteries and plasma pro-oxidant and antioxidant activity. Seven experienced divers performed six dives in six consecutive days using a compressed mixture of oxygen, helium and nitrogen (trimix) with diving depths ranging from 55 to 80 m. Before and after first, third and sixth dive, venous gas emboli formation and brachial artery function (flow-mediated dilation, FMD) was assessed by ultrasound. In addition, plasma antioxidant capacity (AOC) was measured by ferric reducing antioxidant power, and the level of oxidative stress was assessed by thiobarbituric acid-reactive substances (TBARS) method. Although the FMD was reduced to a similar extent after each dive, the comparison of predive FMD showed a reduction from 8.6% recorded before the first dive to 6.3% before the third (P = 0.03) and 5.7% before the sixth dive (P = 0.003). A gradual shift in baseline was also detected with TBARS assay, with malondialdehyde values increasing from 0.10 ± 0.02 μmol l⁻¹ before the first dive to 0.16 ± 0.03 before the sixth (P = 0.005). Predive plasma AOC values also showed a decreasing trend from 0.67 ± 0.20 mmol l⁻¹ trolox equivalents (first day) to 0.56 ± 0.12 (sixth day), although statistical significance was not reached (P = 0.08). This is the first documentation of acute endothelial dysfunction in the large conduit arteries occurring after successive deep trimix dives. Both endothelial function and plasma pro-oxidant and antioxidant activity did not return to baseline during the course of repetitive dives, indicating possible cumulative and longer lasting detrimental effects.

Benthic impacts of recreational divers in a Mediterranean Marine Protected Area

Abstract Luna, B., Valle Pérez, C., and Sánchez-Lizaso, J. L. 2009. Benthic impacts of recreational divers in a Mediterranean Marine Protected Area. – ICES Journal of Marine Science, 66: 517–523. The features of many Marine Protected Areas (MPAs) have increased scuba diving tourism in these areas. Impacts caused by recreational scuba activity vary widely among different divers with differing underwater behaviour. We studied diver underwater behaviour, the effects on the natural environment, and the characteristics that may influence diver behaviour. In all, 181 recreational divers were followed, and contacts and the effects produced were recorded. Information on diver profile and dive features was recorded. Field sampling revealed that 175 of the divers observed (96.7%) made at least one contact with the seabed, with a mean contact of 41.20 ± 3.55 (mean ± s.e.) per diver per 10 min. Flapping was the most frequent type of contact, and the main damage by this action was to raise sediment. Contact with the seabed was greater for males than for females, inexperienced divers than for experienced divers, camera or lantern (dive light) users than for non-users, and divers unaccompanied by a dive leader or who had not been briefed about avoiding seabed contact before undertaking a dive than for accompanied or briefed divers. A greater understanding of the causes of harmful behaviour may be useful for stricter management, reducing diving damage and assuring the sustainability of this activity in MPAs.

Human Auditory Localisation in a Distorted Environment: Water

This study is concerned with sound localisation abilities in water, where the cues for localisation are theoretically severely altered. The main goal of the study was to understand the discrepancy between the poor localisation abilities predicted by the degree of cues alteration and the relatively good performance empirically measured in past investigations. Nine experienced divers performed 8-alternative forced-choice identification tests in open water, with auditory targets presented both in the frontal and rear parts of the horizontal plane. Targets were trains of 300-ms bursts with 25-ms rise/decay times. Bursts were either pure tones (0.4, 1, 6 or 8 kHz) or white noise. With 0.4-kHz tones, the subjects exhibited very accurate left-right distinction and acceptable azimuth resolution. Four subjects made frequent front-back reversals. Also, a bias of the responses towards the median axis was observed in 24% of the data. Six subjects tested with head motion either restricted or free all showed a clear drop of front-back reversals due to head motion. Three subjects tested with all target frequencies exhibited correct localisation accuracy with the white noise, again associated with frequent front-back reversals for two of them. With the 1-, 6- and 8-kHz tones, however, results varied more between individuals. The same three subjects were tested with both the head-conduction and the ear-conduction pathways available, with the head-conduction path blocked off by the wear of a neoprene hood, and with the ear-conduction path blocked off by the wear of neoprene earplugs, in random order. They showed a strong degradation due to the covering of the ear-conduction pathway.

Blood Platelet Count and Bubble Formation After a Dive to 30 msw for 30 min

Previous human studies reported that platelet count (PC) is decreased following decompression. Platelet aggregation and adherence to the bubble surface has been demonstrated in severe decompression sickness (DCS). The present study was designed to clarify the relationship between post-dive changes in blood PC and the level of bubble formation in divers. There were 40 healthy experienced divers who were assigned to 1 experimental group (N = 30) with an open-sea air dive to 30 msw for 30 min in field conditions and 1 control group (N = 10) without hyperbaric exposure. Bubble grades were monitored with a pulsed Doppler according to the Spencer scale and Kissman integrated severity score (KISS). Blood samples for red blood cell counts (RBC), hematocrit (Hct), and PC were taken 1 h before and after exposure in two groups. None of the divers developed any signs of DCS. In two groups, the results showed significant increase in RBC count and Hct related with hemoconcentration and no change in PC. Divers with a high KISS score (39 +/- 5.8; mean +/- SD) presented a significantly more pronounced percent fall in PC than divers with a lower KISS score. We found a significant correlation between the percent fall in PC after a dive and the bubble KISS score. The present study highlighted a relationship between the post-dive decrease in PC and the magnitude of bubble level after decompression. Our primary result is that the post-dive decrease in PC could be a predictor of decompression severity after diving.

Decompression Illness Reported in a Survey of 429 Recreational Divers

The purpose of this study was to investigate the influence of diving experience and diving techniques on the lifetime incidence of decompression illness (DCI). Attendants of three diving medical symposia voluntarily answered a questionnaire about their age, gender, medical history, diving experience, diving habits, diving certification levels, and diving associated incidents (cross-sectional survey). Out of 650 divers, 429 completed the questionnaire. The study population consisted of experienced divers with an average of 670 dives. The majority of the divers were certified diving instructors (43%). There were 37 participants (8.7%) who were classified as technical divers with an average of 1193 logged dives. There was an overall lifetime incidence of DCI of 1 per 5463 dives. The complete study group showed an increased lifetime incidence of DCI with decreased diving experience (1.97-fold to 8.17-fold higher). Of the divers, 27% reported severe DCI with neurological symptoms. The lifetime incidence for severe DCI was 1 in 20,291 dives. Again, lifetime incidence for severe DCI was increased with decreased diving certification level (1.1-fold to 13.7-fold higher). Technical divers showed a DCI lifetime incidence of 1 to 8591 dives compared to the non-technical divers with a lifetime incidence of 1 to 5077 dives (not significant). In our study population, the lifetime incidence of DCI was increased in divers with less diving experience. If further studies confirm this finding, diving federations should be encouraged to intensify their efforts of educating divers and should limit diving time and depth in inexperienced divers.

Hals-Nasen-Ohren ärztliche Erkrankungen im Zusammenhang mit dem Sporttauchen

Due to the increasing number of scuba divers in Germany, the otorhinolaryngologist has to face rising numbers of diving-associated ENT disorders. However, data about the lifetime prevalence of these disorders are insufficient. The aim of this study was to determine the frequency of ENT disorders in scuba divers correlated with their diving history. The study design was a non-randomized, retrospective, cross-sectional study based on questionnaires. The study population included 429 active divers attending three medical diving symposia. The study population consisted of highly experienced divers (mean of logged dives m= 670.0) with a high diving certification level. Otitis externa was the most frequent disorder (43.6%). Barotrauma of the sinuses (10.9%), alternobaric vertigo (9.0%) and barotrauma of the middle ear (8.7%) played an important role as well. In contrast, inner ear barotrauma and decompression illness of the inner ear were less frequent but not rare (1.7 % each). A substantial number of scuba divers suffered diving-related ENT disorders.

Étude prospective sur les accidents de décompression ostéomyoarticulaires en plongée de loisir : leurs facteurs de risque et leur potentiel évolutif en ostéonécrose dysbarique

Objectives Dysbaric osteonecrosis is a complication that can result from repetitive and prolonged hyperbaric exposures and the correlation with a previous type 1 decompression sickness described as a joint pain remains a controversial subject. The study was designed to determine the risk factors of type 1 decompression sickness in recreational divers and their potential to shortly evolve into osteonecrosis. Methods All the osteoarthromuscular decompression sickness treated between October 2004 and November 2005 in one of three hyperbaric centers assigned in the Provence-Alpes-Côte d'Azur region were analyzed in a prospective way of standardized collections, and the majority was explored with MRI in order to screen ischaemic osteomedullar damages. Results Eleven cases (8,5%) were inventoried amongst the 129 diving accidents treated during this period. These joint pains were mainly located in the shoulder area (81%) and involved a majority of male experienced divers after performing deep and long dives (90%) furthermore more than 50% of these divers had greater than one dive within a twelve hour period. The average age was 38,5 years with a body mass index of 27,5 kg/m 2. All dives were performed with a dive computer without omitted decompression. Ten injured divers (90%) were examined by MRI shortly after the accident, but only one diver (10%) had lesions compatible with osteonecrosis. Conclusion This preliminary study shows that osteoarthromuscular decompression sickness in recreational diving are essentially involved in dives considered to carry a high risk for bubble production. The conditions of occurence appear also to be related with some individual factors that must be specified in other studies. Nevertheless, the risk of early underlying dysbaric osteonecrosis development is quite low.

The effects of acute oral antioxidants on diving‐induced alterations in human cardiovascular function

Diving-induced acute alterations in cardiovascular function such as arterial endothelial dysfunction, increased pulmonary artery pressure (PAP) and reduced heart function have been recently reported. We tested the effects of acute antioxidants on arterial endothelial function, PAP and heart function before and after a field dive. Vitamins C (2 g) and E (400 IU) were given to subjects 2 h before a second dive (protocol 1) and in a placebo-controlled crossover study design (protocol 2). Seven experienced divers performed open sea dives to 30 msw with standard decompression in a non-randomized protocol, and six of them participated in a randomized trial. Before and after the dives ventricular volumes and function and pulmonary and brachial artery function were assessed by ultrasound. The control dive resulted in a significant reduction in flow-mediated dilatation (FMD) and heart function with increased mean PAP. Twenty-four hours after the control dive FMD was still reduced 37% below baseline (8.1 versus 5.1%, P = 0.005), while right ventricle ejection fraction (RV-EF), left ventricle EF and endocardial fractional shortening were reduced much less (approximately 2-3%). At the same time RV end-systolic volume was increased by 9% and mean PAP by 5%. Acute antioxidants significantly attenuated only the reduction in FMD post-dive (P < 0.001), while changes in pulmonary artery and heart function were unaffected by antioxidant ingestion. These findings were confirmed by repeating the experiments in a randomized study design. FMD returned to baseline values 72 h after the dive with pre-dive placebo, whereas for most cardiovascular parameters this occurred earlier (24-48 h). Right ventricular dysfunction and increased PAP lasted longer. Acute antioxidants attenuated arterial endothelial dysfunction after diving, while reduction in heart and pulmonary artery function were unchanged. Cardiovascular changes after diving are not fully reversed up to 3 days after a dive, suggesting longer lasting negative effects.

No changes in lung function after a saturation dive to 2.5 MPa with intermittent reduction in $$ P_{{{{\rm O}}_{{{\rm 2}}} }} $$ during decompression

Decompression stress and exposure to hyperoxia may cause a reduction in transfer factor of the lung for carbon monoxide and in maximal aerobic capacity after deep saturation dives. In this study lung function and exercise capacity were assessed before and after a helium-oxygen saturation dive to a pressure of 2.5 MPa where the decompression rate was reduced compared with previous deep dives, and the hyperoxic exposure was reduced by administering oxygen intermittently at pressures of 50 and 30 kPa during decompression. Eight experienced divers of median age 41 years (range 29-48) participated in the dive. The incidence of venous gas microemboli was low compared with previous deep dives. Except for one subject having treatment for decompression sickness, no changes in lung function or angiotensin converting enzyme, a marker of pulmonary endothelial cell damage, were demonstrated. The modified diving procedures with respect to decompression rate and hyperoxic exposure may have contributed to the lack of changes in lung function in this dive compared with previous deep saturation dives.

Ventilatory Function in Experienced Recreational Scuba Divers: Evidence of Small Airways Disease?

Diving has shown long-term effects on respiratory function in trained professional divers, indicating the development of small airways disease. The results are more controversial in trained recreational divers because of the different degrees of exposure and training. The aim of this study was to investigate the effects of recreational diving on respiratory function in highly experienced divers. Volumes and expiratory flow rates were measured in 32 older recreational divers (51.6 +/- 7.4 years). The forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were higher (+ 4.9 % and + 6 %, respectively; p < 0.01) than the theoretical standards (ERS 93). These values tended to decrease more rapidly as the age advanced (age range: 43 - 73 years) (p < 0.05). Moreover, the mid-expiratory flows at 50 %, 25 % and 25 - 75 % of vital capacity (MEF(50 %), MEF(25 %) and MEF(25 - 75 %)) were significantly decreased. These early signs of decrease suggest slight small airways disease in older experienced recreational divers.

Large Lungs in Divers: Natural Selection or a Training Effect?

Normal spirometry is required for medical clearance of professional divers in many countries. Divers frequently have unusually large lung volumes associated with a low ratio of FEV(1) to FVC (FEV(1)%), suggestive of obstructive airways disease. We retrospectively analyzed the records of divers in the Israeli Navy with a low FEV(1)% who fulfilled the criteria for large lungs, to determine whether this might be the effect of training or natural selection. We also investigated changes in pulmonary function in relation to diving experience.A total of 171 divers with FEV(1)% < 80% on simple spirometry were evaluated. We conducted a retrospective analysis of lung function data for those subjects who met the criteria for large lungs.One hundred nine of 171 divers with low FEV(1)% met the criteria for large lungs and were included in the study. Their average age was 25 years (range, 18 to 44 years), and their mean diving experience was 7 years (range, 0 to 26 years). No difference was found in FVC values between experienced and inexperienced divers. The mean forced expiratory flow at 50% of vital capacity was significantly reduced in the most experienced group compared with the novice or less experienced divers. No difference was found in the diffusing capacity of the lung for carbon monoxide between experienced and inexperienced divers.We suggest that large lungs may represent part of the natural selection for diving, rather than a training effect. Prolonged diving experience may result in the development of small airways disease.

Experienced scuba divers in Australia and the United States suffer considerable injury and morbidity.

Scuba diving-specific injuries have been well described. However, the injury experiences of individual divers over long diving careers have rarely been investigated. Our objective was to study the acute and chronic injuries of experienced, recreational scuba divers. This was an international, cross-sectional, descriptive postal survey of experienced, recreational scuba divers belonging to diving clubs in Australia and the United States. Seven hundred nine divers were enrolled (346 Australian divers and 363 US divers). Most participants were experienced (mean number of dives, 262) male divers (488; 68.8%) aged 31 to 50 years (425; 59.9%). Mild barotrauma was common. Ear, sinus, and tooth "squeeze" had been experienced on > or = 1 occasion by 369 (52.1%), 245 (34.6%), and 66 (9.2%) divers, respectively. Tympanic membrane (TM) rupture, round/oval window rupture, and subcutaneous emphysema had been experienced by 38 (5.4%), 8 (1.1%), and 5 (0.7%) divers, respectively. No diver reported pneumothorax or arterial gas embolism (AGE); however, 31 divers (4.4%) had suffered decompression sickness (DCS). A wide range of other injuries were reported. Sixteen divers (2.3%) reported permanent disabilities, which largely consisted of hearing loss, tinnitus, and balance disorder. The majority of experienced divers who responded to the survey had suffered diving-related injuries, mainly barotrauma. Further research and diver education are needed to better document injury rates and minimize serious diving-related injuries and permanent disabilities.

Recreational scuba diving, patent foramen ovale and their associated risks.

Scuba diving has become a popular leisure time activity with distinct risks to health owing to its physical characteristics. Knowledge of the behaviour of any mixture of breathable gases under increased ambient pressure is crucial for safe diving and gives clues as to the pathophysiology of compression or decompression related disorders. Immersion in cold water augments cardiac pre- and afterload due to an increase of intrathoracic blood volume and peripheral vasoconstriction. In very rare cases, the vasoconstrictor response can lead to pulmonary oedema. Immersion of the face in cold water is associated with bradycardia mediated by increased vagal tone. In icy water, the bradycardia can be so pronounced, that syncope results. For recreational dives, compressed air (i.e., 4 parts nitrogen and 1 part oxygen) is the preferred breathing gas. Its use is limited for diving to 40 to 50 m, otherwise nitrogen narcosis ("rapture of the deep") reduces a diver's cognitive function and increases the risk of inadequate reactions. At depths of 60 to 70 m oxygen toxicity impairs respiration and at higher partial pressures also functioning of the central nervous system. The use of special nitrogen-oxygen mixtures ("nitrox", 60% nitrogen and 40% oxygen as the typical example) decreases the probability of nitrogen narcosis and probably bubble formation, at the cost of increased risk of oxygen toxicity. Most of the health hazards during dives are consequences of changes in gas volume and formation of gas bubbles due to reduction of ambient pressure during a diver's ascent. The term barotrauma encompasses disorders related to over expansion of gas filled body cavities (mainly the lung and the inner ear). Decompression sickness results from the growth of gas nuclei in predominantly fatty tissue. Arterial gas embolism describes the penetration of such gas bubbles into the systemic circulation, either due to pulmonary barotrauma, transpulmonary passage after massive bubble formation ("chokes") or cardiac shunting. In recreational divers, neurological decompression events comprise 80% of reported cases of major decompression problems, most of the time due to pathological effects of intravascular bubbles. In divers with a history of major neurological decompression symptoms without evident cause, transoesophageal echocardiography must be performed to exclude a patent foramen ovale. If a cardiac right-to-left shunt is present, we advise divers with a history of severe decompression illness to stop diving. If they refuse to do so, it is crucial that they change their diving habits, minimising the amount of nitrogen load on the tissue. There is ongoing debate about the long term risk of scuba diving. Neuro-imaging studies revealed an increased frequency of ischaemic brain lesions in divers, which do not correlate well with subtle functional neurological deficits in experienced divers. In the light of the high prevalence of venous gas bubbles even after dives in shallow water and the presence of a cardiac right-to-left shunt in a quarter of the population (i.e., patent foramen ovale), arterialisation of gas bubbles might be more frequent than usually presumed.

Recreational scuba diving, patent foramen ovale and their associated risks.

Scuba diving has become a popular leisure time activity with distinct risks to health owing to its physical characteristics. Knowledge of the behaviour of any mixture of breathable gases under increased ambient pressure is crucial for safe diving and gives clues as to the pathophysiology of compression or decompression related disorders. Immersion in cold water augments cardiac pre- and afterload due to an increase of intrathoracic blood volume and peripheral vasoconstriction. In very rare cases, the vasoconstrictor response can lead to pulmonary oedema. Immersion of the face in cold water is associated with bradycardia mediated by increased vagal tone. In icy water, the bradycardia can be so pronounced, that syncope results. For recreational dives, compressed air (i.e., 4 parts nitrogen and 1 part oxygen) is the preferred breathing gas. Its use is limited for diving to 40 to 50 m, otherwise nitrogen narcosis ("rapture of the deep") reduces a diver's cognitive function and increases the risk of inadequate reactions. At depths of 60 to 70 m oxygen toxicity impairs respiration and at higher partial pressures also functioning of the central nervous system. The use of special nitrogen-oxygen mixtures ("nitrox", 60% nitrogen and 40% oxygen as the typical example) decreases the probability of nitrogen narcosis and probably bubble formation, at the cost of increased risk of oxygen toxicity. Most of the health hazards during dives are consequences of changes in gas volume and formation of gas bubbles due to reduction of ambient pressure during a diver's ascent. The term barotrauma encompasses disorders related to over expansion of gas filled body cavities (mainly the lung and the inner ear). Decompression sickness results from the growth of gas nuclei in predominantly fatty tissue. Arterial gas embolism describes the penetration of such gas bubbles into the systemic circulation, either due to pulmonary barotrauma, transpulmonary passage after massive bubble formation ("chokes") or cardiac shunting. In recreational divers, neurological decompression events comprise 80% of reported cases of major decompression problems, most of the time due to pathological effects of intravascular bubbles. In divers with a history of major neurological decompression symptoms without evident cause, transoesophageal echocardiography must be performed to exclude a patent foramen ovale. If a cardiac right-to-left shunt is present, we advise divers with a history of severe decompression illness to stop diving. If they refuse to do so, it is crucial that they change their diving habits, minimising the amount of nitrogen load on the tissue. There is ongoing debate about the long term risk of scuba diving. Neuro-imaging studies revealed an increased frequency of ischaemic brain lesions in divers, which do not correlate well with subtle functional neurological deficits in experienced divers. In the light of the high prevalence of venous gas bubbles even after dives in shallow water and the presence of a cardiac right-to-left shunt in a quarter of the population (i.e., patent foramen ovale), arterialisation of gas bubbles might be more frequent than usually presumed.

Sustainable dive ecotourism on a South African coral reef

SCUBA ecotourism provides economic support for local human communities and for conservation. Such support should be sustainable and as ecologically non-destructive as possible to its coral reef foundation. In recent years, the major increase in SCUBA activity has become a significant consideration at some locations. Among these are the South African coral reefs at Sodwana Bay, which receive 80 000 dives per year. Between May 1998 and January 1999, assessments using line-intercept and belt transects showed that 5.9% of hard corals and 4.0% of soft corals were damaged from various causes, while only 0.02% of the hard corals were dead. Of the 222 diver contacts observed, only 1.63% produced instant and visually-clear damage, with no measurable decline in overall coral reef health. Direct observations on 89 recreational divers showed that photographers made damaging contacts on nine out of ten dives, while novice divers made one such contact per six dives, moderately experienced divers about once every 14 dives, and very experienced divers about once every 123 dives. Increased time lapsed since the last dive increased diver damage by novices. We calculated that the 80 000 dives were equivalent to 1 m2 of reef receiving 2.3 diver contacts per year. Acropora austera was by far the most significantly damaged coral, with one out of four branches broken per year. But as this species accounted for only 0.2% of reef benthos cover, this impact was not representative of overall reef health. This heavy species-specific impact makes A. austera a good bio-monitor.

Effects of Environment &amp; Experience on Underwater Work Performance

Five experienced divers and 15 novice divers completed a complex underwater asembly task and sets of written problems in a water-filled tank and in the ocean. Performance measurements included subtask completion times, problem-solving accuracy, activity analysis, and basic physiological variables. Experienced divers showed essentially unchaged performance between tank and ocean. Novice divers performend slower than the experienced divers in the tank and showed a makred decrement in both assembly time and problem-solving accuracy in the ocean. The results suggest that diving experinece improves underwater motor skills rather than work strategy, and that psychological stress was a significant factor even at shallow ocean depths for novices.

Research on nitrogen-oxygen saturation diving with repetitive excursions.

For some tasks of underwater operation the need for longer dive duration and more working divers necessitates the use of saturation diving techniques with excursions. Saturation diving with excursion has high working efficiency. A collaborative experiment with Chinese Underwater Technology Institute, American National Office of Research Undersea Program and Hamilton Research Ltd. was conducted at our Institute in Shanghai. The main experiment objectives were to assess the longer, deeper repetitive excursions during nitrogen-oxygen saturation situation, oxygen exposure management, nitrox saturation decompression after excursions and performance aspects. Four Chinese professional experienced divers were saturated at 25 msw for 5 days at the hyperbaric facility, where they did 15 air excursions to depths between 50 and 75 msw, for duration up to 240 min. Decompression from excursions to the storage were mostly no-stops, but 5 required stops for 3 to 116 min. Saturation decompression began with the "precursory" ascent following a brief return to 25 msw. Doppler bubble detection showed some bubbles of Spencer Grade II and occasionally III, following excursions and during saturation decompression, especially after muscle flexing. No symptoms of decompression sickness were reported: one diver was more of fatigued on one occasion than other times. Oxygen exposure reached its peak of 3103 Oxygen Toxicity Units on Day 6. The only subjective symptom of oxygen toxicity was mild and transient numb fingertips. No significant change was seen in vital capacity.

Atopy, Airway Reactivity and Compressed Air Diving in Males

A decline in expiratory flow rates in divers has recently been attributed to chronic exposure to hyberbaric air. Airway hyperresponsiveness (AHR) to stimuli due to a hyperbaric environment may play a certain role in this context. The aim of this study was to determine the prevalence of AHR in compressed air divers and to assess the value of bronchial challenges for prediction of fitness to dive. A cross-sectional sample of 59 healthy male volunteers – 28 divers and 31 diving candidates (controls) – who had been found fit to dive in a diving medical examination underwent additional allergy screening (skin prick and serum IgE) and a histamine bronchial challenge. Pre- and postchallenge body plethysmography was completed to assess AHR. AHR to histamine was significantly increased among divers and positively related to diving experience whereas divers and controls did not differ significantly with respect to age, anthropometric data, current smoking habits, skin prick reaction, and elevated serum IgE. Our results indicate an increased prevalence of AHR to nonspecific inhalation stimuli in experienced divers. Bronchial challenge tests may be helpful to detect asthmatics in the medical assessment of fitness to dive and for follow-up examinations during a diver’s career.

Psychological aspects of scuba diving injuries: Suggestions for short-term treatment from a psychodynamic perspective

Dive medicine is described as an area of practice in which psychologists may choose to expand their clinical service and research activities. The author argues that most research studying risk behavior and sports take into account biological, behavioral or cognitive approaches, while ignoring unconscious conflict in risk-taking and injury management. The present paper uses a psychodynamically-oriented, interview-based approach to studying psychological reactions to decompression sickness in three experienced scuba divers. Brief interventions and their outcomes are described.

Serum antibody responses of divers to waterborne pathogens.

To assess the significance of exposure of divers to waterborne pathogens, specific immunoglobulin G serum antibody responses to Pseudomonas and Aeromonas isolates recovered from dive sites from the respiratory tracts of nine experienced divers and seven diving trainees working in the Chesapeake Bay area over a 6- to 18-month period were measured. A significant increase in the frequency of isolation of these organisms from respiratory surfaces both groups of divers after each dive was noted, with the divers' ears being the predominant recovery site (48%; P < 10(-8), chi-square). The acute serum responses of the majority of experienced divers (83%) showed evidence of preexisting antibody to these potential pathogens, whereas the acute serum response of only 32% of naive divers showed such evidence (P < 10(-8), chi-square). Six months into their training, the rate of seroresponse of the trainees to organisms recovered after their first dives increased to 61% (P = 0.003, chi-square), suggesting that repeated exposure in necessary for generation of a specific systemic immunologic response. The rate of acquisition of a new seroresponse to recovered organisms was approximately 12% per dive for both groups of divers, suggesting that there is continuous exposure to, and infection with, new strains present in the water during dives. These data suggest that, in cases in which systemic antibody is important for protection, there are various levels of susceptibility to waterborne potential pathogens in both experienced and inexperienced divers.