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PubMed2001

Environmental stress on diving-induced platelet activation.

Platelet activation has been suggested to play an important role in the pathogenesis of prethrombotic states and thus may be responsible for decompression illness during compressed air (scuba) diving. To investigate the effect of physical, mental, and environmental stress on platelet activation during immersion in ice-cold water, we examined 10 male breath-hold divers (BHD), 10 elite BHD (eBHD), and 10 scuba divers during immersion in an ice-covered lake at moderate altitude. Platelet activation was examined by surface expression of activation-dependent glycoproteins CD62p, CD63, and CD42a with flow cytometry 10 min before and 1 min and again 24 h after diving. Plasma epinephrine level was also measured. In addition, the relationship between the activated platelets and the epinephrine level was evaluated. The percentage of platelet activation increased from 2.1 +/- 0.4 to 5.7 +/- 0.3, 1.8 +/- 0.3 to 12.9 +/- 0.8, and 3.7 +/- 0.9 to 31.2 +/- 0.8 in BHD, eBHD, and scuba divers, respectively. The percentage of platelet activation returned to pre-immersion levels in BHD and eBHD divers 24 h after diving, but was still higher in scuba divers. A positive relationship exists between the plasma epinephrine level and the percentage of the platelet activation. This study suggests that physical and mental stress enhance platelet activation during diving in ice-cold water.

Adult↗
PubMed2002

Internal carotid artery dissection in stroke from SCUBA diving: a case report.

Although diving with compressed air is generally safe, neurological problems resulting from infarction in SCUBA diving are well known, including arterial gas embolism and decompression sickness (caisson's disease, bends) involving the brain and spinal cord. While air gas embolism forms the overwhelming majority of causes for stroke in divers, internal carotid artery (ICA) dissection is another potential mechanism for central nervous system infarction in the setting of SCUBA diving. A 38 year-old female, who presented with complaints of headache, nausea, vomiting, and left sided hemiparesis after rapid ascent to the surface from a depth of 120 feet of seawater was initially treated for decompression illness in a hyperbaric chamber. Further neurological workup revealed a right ICA dissection. This case demonstrates the dangers of ICA dissection following rapid ascent to the surface from underwater and emphasizes an interesting presentation of stroke associated with SCUBA diving.

Adult↗
PubMedDate not supplied

[The characteristics of the extreme actions on the bodies of deep-sea divers during saturation dives and the basic task of medical support for these descents].

A novel dive method, namely, saturation diving is presented. Extreme factors affecting the deep divers during such saturation dives are listed. The physiologic parameters of early adaptation, stable adaptation, early disadaptation and readaptation periods of a man during prolonged staying in a hyperbaric artificial gaseous environment are evaluated. The key task of medical monitoring of saturation dives is discussed.

Adaptation, Physiological↗
PubMed1992

Effect of mental task load on fronto-central theta activity in a deep saturation dive to 450 msw.

The increase of theta activity (4-7 Hz) in the electroencephalogram (EEG) during deep diving is commonly attributed to pathophysiologic mechanisms underlying the high pressure neurologic syndrome. The aim of this study was to clarify whether more precise cognitive aspects of the condition may be described in which theta activity occurs during a deep dive. Among 4 divers who were repeatedly examined during the GUSI 14 dive to 450 msw, 3 divers exhibited a pronounced correlation between short-term memory load, as varied by the memory set size of Sternberg's memory search task (MST), and the size of a distinct peak in the theta band of the EEG-power spectrum. The power of this peak was greatest in the fronto-central electrode position (Fz), increased dramatically during MST-performance at pressure, and failed to subside fully 1 day before surfacing. Despite the close dependency of observed theta activity on cognitive demands, no consistent correlation with performance measures (mean reaction time and errors) was found. In one diver, theta waves of similar morphology appeared in the resting EEG and increased significantly during the dive. We suggest two alternative explanations for the positive interaction of memory load and hyperbaric exposure on Fz-theta: a) Both factors induce a state of increased mental effort or selectivity of attention, known to be accompanied by frontal theta activity from normobaric studies. b) Pressure abnormally facilitates or patterns rhythmical excitations underlying theta activity that would occur naturally to a lesser extent during certain mental activities, learning, or repetitive short-term memory operations.

Adult↗
PubMed1992

Evaluation of energy requirements from body mass, lean body mass, fat content, and energy intake in GUSI dives.

This study reports the changes in body composition measured during 6 deep saturation dives, the depths and the working hours performed during the dives, and the effects of these parameters on the energy requirements. Changes in lean body mass could be avoided if the working days amounted to 40-45% of the total dive time. Energy requirement depended not only on working days but also on the diving depth. Physical work at great depth requires a disproportional increase in the energy requirements beginning between 200 and 360 m. Under working conditions at 450 msw, energy requirements increased about 30% relative to the total energy needs under normal conditions.

Adult↗
PubMed2004

[Recreational diving accidents in Sweden].

Even if recreational diving is gradually becoming safer, the 2-6 fatalities each year is the most serious problem in recreational diving. Human factors are behind 75% of the fatalities and medical problems seldom cause fatalities. On average 40 recreational divers are treated with recompression each year. Signs and symptoms are in general mild and only few sequelas are seen. The number of traumas to ear/balance organs, sinuses, lungs etc are difficult to estimate but these are most likely not a large part of all patients in the health care. It is currently difficult to estimate the risks in recreational diving since there is no exact information on the number of dives that are performed each year.

Athletic Injuries↗
PubMed2004

[Breath-hold diving--an increasing adventure sport with medical risks].

Breath-hold diving as a recreational and competitive sports activity is on the increase. In this review physiological limitations and medical risks associated with breath-hold diving are discussed. Specific topics include hypoxia, ascent blackout, hyperventilation, squeeze or barotrauma of descent including effects on the pulmonary system, glossopharyngeal breathing, and decompression illness. It is also concluded that the health requirements for competitive breath-hold diving should follow essentially the same standards as used for SCUBA-diving.

Apnea↗
PubMed2004

Leukotriene-B4 concentrations in breathing condensate before and after simulated deep dives.

During diving the respiratory tract is exposed to occupational hazards (increased oxygen partial pressure, pulmonary vessel engorgement during submersion, inert gas micro embolism during decompression). Leukotriene-B4 [LTB4] concentrations in the exhaled breath mirrors the inflammatory activity of the airways if the respiratory tract has been exposed to occupational hazards. In this study LTB4-concentrations in the exhaled breath and spirometry data obtained before and after simulated dives helped to elucidate any contributions by hyperbaric exposure to impaired lung function and to separate effects of ambient pressure from those of submersion and increased oxygen partial pressure. Thirty two healthy subjects carried out dives in a hyperbaric chamber using a cross over design to 600 kPa ambient pressure with and without submersion and a dry exposure to pure oxygen at 120 kPa ambient pressure (durations: 43 min). Pre-dive and four hours after surfacing the exhaled breath was collected non-invasively. Condensate was measured by a standard enzyme immuno-assay for LTB4 in parallel with lung function values (FVC, FEV1, MEF 25-75). Pre-exposure baseline values of LTB4-concentrations and lung function values were in the normal range. Post-exposure values did not differ significantly from the baseline values. The data gave no evidence of any inflammatory activity in the subjects' airways after hyperbaric exposure.

Adult↗
PubMed1975

Nausea and abdominal discomfort--possible relation to aerophagia during diving: an epidemiologic study.

Gastrointestinal (GI) distension by gas expansion may be more of a problem in diving than is usually recognized. In response to a written questionnaire, 2053 scuba divers gave information about GI discomfort such as pain, nausea, and vomiting in connection with diving. One hundred and eleven reports (5.4% of 2053) were considered possible cases of significant GI distension because the majority of divers had their symptoms during ascent and a significant number of them got relief from belching. Difficult middle ear pressure equilibration was a particular problem among divers with GI symptoms. It may have induced frequent swallowing, causing air ingestion and consequent GI problems. Steep, head-first descents appear to have been employed in some dives, leading to GI discomfort presumably be creating large mouth-to-stomach gas-pressure differences. It was concluded that swallowing or any procedure leading to entry of gas into the stomach should be avoided and that belching during diving should be recommended.

Abdominal Pain↗
PubMed1992

[Recording the feeding behavior of freely moving animals using the example of freely diving Weddell seals (Leptonychotes weddellii)].

During the antarctic summer 1990, the pattern of food intake in comparison to diving-activity was investigated on adult Weddell seals. Diving depths were recorded by a time-depth recorder (TDR). The TDR is a free programmable electronic datalogger, which can store data on up to 5 channels. It was fixed on the fur of the seal, ensuring that no longer lasting irritation of the animal was caused. The pattern of food-intake was monitored by measuring the jaw-movements, using strain gauges for recording the deformation of the muscles by mastication. After electronic amplification and filtering, the frequency of jaw-activity within a measuring period was recorded one channel of the TDR. By simultaneously observing the diving depths, these data may lead to conclusions about chewing patterns of the seal in water depths where they catch prey. The graph of these data and the mathematical evaluation by Fourier analysis and Plexogramme show a close correlation between diving depth and jaw-activity.

Animals↗
PubMedDate not supplied

A simple probabilistic model for standard air dives that is focused on total decompression time.

A statistical fit of an algorithm to "calibration data" gives parameter values for a "probabilistic decompression model." Our objective is to prepare a simple model that will estimate risk of decompression sickness (DCS) in air dives. We develop a logistic regression model using calibration data from carefully controlled experimental dives recorded in the U.S. Navy Decompression Database. We exclude saturation dives, which can have very long decompression times. For most depths, our model's prescriptions for 2% probability of DCS avoid the experimental DCS cases without mandating excessive time at decompression stops. Our model indicates that the long decompression times prescribed by some previous probabilistic models are not necessary. Our model cannot be used operationally because it cannot calculate depths and times at decompression stops; however, there is general concurrence between our model and prescriptions of a deterministic model known as the VVal-18 Algorithm; this supports the adoption of theVVal-18 Algorithm for operational use on decompression dives.

Air↗
PubMed2005

[The predictive value of assessing mastoid pneumatization in pre-dive examinations].

OBJECTIVES: We investigated the value of assessing the degree of mastoid pneumatization in predicting middle ear barotrauma -the most common problem in sport SCUBA divers- in comparison with that of the conventional pre-dive examination method, the Valsalva maneuver. MATERIALS AND METHODS: Thirty-four volunteer sport SCUBA divers having normal pre-dive examination findings were included. The Valsalva test was performed in all the divers. Mastoid pneumatization for each ear was calculated on a Schuller's view radiography. Pneumatization of = or <30 cm2 was accepted as poor (prone to barotrauma) and >30 cm2 was accepted as good (not prone to barotrauma). During the observation period, the divers were monitored with regard to barotrauma symptoms and signs. RESULTS: The degree of mastoid pneumatization was = or <30 cm2 in 26 ears (38%) of 16 divers (47%). The Valsalva test was negative in eight ears (12%) of six divers (18%). During a total of 1001 dives, symptomatic middle ear barotrauma occurred in 28 dives (2.8%), i.e. in 21 ears (31%) of 16 divers (47%). Of these, the degree of mastoid pneumatization predicted barotrauma in 11 (69%) divers, whereas the Valsalva test was negative in only three (19%) (p<0.05), with sensitivity, specificity, positive and negative predictive values, and efficiency being 69% and 19%, 72% and 83%, 69% and 50%, 72% and 54%, and 71% and 53%, respectively. CONCLUSION: The value of assessing mastoid pneumatization in predicting middle ear barotrauma in sport SCUBA divers is higher than that of the Valsalva test.

Adolescent↗
PubMedDate not supplied

Adverse events in competitive breath-hold diving.

Medical observations are reported from an eight-day world championship breath-hold diving competition involving 57 participants. The deepest dive was to 75 metres, and the longest breath-hold time exceeded 9 minutes. There were 35 diving-related adverse events witnessed or reported, including transient loss of motor control due to hypoxia, syncope during ascent, hemoptysis, and pulmonary edema. All events occurred in healthy individuals, and resolved without apparent sequelae. There was no relationship between symptoms and depth. The medical implications of these adverse events are discussed. Despite the inherent risks of the sport, established organizational procedures for competitive breath-hold diving maintain a high degree of safety.

Adult↗
PubMed2006

Plasma glutathione peroxidase activity as a potential indicator of hypoxic stress in breath-hold diving.

INTRODUCTION: Diving mammals can cope with oxidants which are produced in excess during the reoxygenation of hypoxic tissues. This study addresses the question of whether antioxidants can adapt and whether it allows humans to tolerate the hypoxic stress induced by a single breath-holding in the course of a dynamic diving exercise and protect them from oxidative insult. METHODS: There were 20 male subjects who performed submaximal apnea dynamic diving (ADD). Nine control subjects stayed out of the water and breathed normally. Venous blood samples were collected 1 h before and immediatly after ADD. RESULTS: ADD induced a significant increase in plasma glutathione peroxidase (GPx-3) activity (from 397.5 +/- 44.4 to 410 +/- 43 U x L(-1)), blood reduced glutathione (GSH) (from 1060 +/- 302 to 1292 +/- 213 micromol x L(-1)), and in plasma creatine kinase activity (from 215 +/- 137 to 235 +/- 152 U x L(-1)). The activity of the erythrocyte superoxide dismutase and glutathione peroxidase, as well as the blood oxidized glutathione and the plasma thiobarbituric acid reactive substances concentrations, were maintained at their basal level. The level of training, characterized by the duration and distance of the dive, had no effect on the markers used. CONCLUSION: GPx-3 and GSH could constitute the most readily mobilizable antioxidants that would then contribute to the buffering against a sudden increase in the generation of radical oxygen species. These biomarkers could be used as tools for establishing oxidative stress during hypoxia. The response of GPx-3 to hypoxia could be of physiological relevance.

Adult↗
PubMedDate not supplied

Diffusing capacity and spirometry following a 60-minute dive to 4.5 meters.

The purpose of this study was to assess the contribution of SCUBA to the pulmonary effects of diving to 4.5 meters depth in healthy subjects using a randomized crossover control condition. Ten healthy divers performed two 60-minute 'dives' using SCUBA in a swimming pool. The non-immersed 1 ATA SCUBA control exposure took place at ambient pressure in the laboratory. Thirty minutes prior to, and 30 and 90 minutes post-exposure, FVC (forced vital capacity), FEV1.0 (forced expired volume), peak expiratory flow rate (PEFR), diffusing capacity (DL(co)), heart rate (HR) and temperature were measured. No significant differences were noted in HR, temperature or spirometry between the two conditions. A significant reduction in diffusing capacity occurred at 30 and 90 minutes after the pool dive (9.3% and 15.1%, respectively, p < 0.05). There was no concordant change in DL(co) following the non-immersed 1 ATA SCUBA control. Thus, a pool dive to 4.5 meters for 60 minutes causes a decrease in DL(co), without a change in spirometry, while breathing from SCUBA equipment without immersion causes no significant change in lung function.

Adult↗
PubMed2006

Glutathione in blood cells decreases without DNA breaks after a simulated saturation dive to 250 msw.

INTRODUCTION: Saturation diving involves exposure to high pressure and elevated oxygen level. The impact of cellular defense systems like glutathione in protecting cells against oxidative DNA damage seems unclear. The aim of the present study was, therefore, to investigate whether diving conditions would affect blood cell glutathione and thus alter the mononuclear cells' (MNC) susceptibility to oxidative DNA damage. METHODS: Eight subjects participated in a simulated saturation dive to 2.6 MPa (250 msw) lasting 19.3 d (0.8 d compression, 6.6 d bottom phase, 11.9 d decompression) breathing helium-oxygen with PO2 ranging from 35 to 70 kPa (3.5-7.0 msw). Blood samples collected before compression and after decompression were analyzed for glutathione content and single-stranded DNA breaks. RESULTS: The results demonstrate for the first time that a simulated saturation dive decreased glutathione content in peripheral blood cells (32% decrease in MNC), and that the decrease was most pronounced in the erythrocytes (45%). Remarkably, no single-stranded DNA breaks could be detected in the MNC despite the low glutathione level. DISCUSSION: The results suggest that glutathione is a useful indicator of oxidative stress and that a low glutathione level represents no significant harm to the blood cells in the absence of other toxic agents. The lack of DNA strand breaks suggests that protection against oxidative DNA damage was mainly provided by mechanisms other than the glutathione system. Although previous investigations point to hyperoxia as the most plausible explanation for the present observations, the effect of high pressure cannot be excluded.

Adult↗
PubMed1991

Psychometric evaluation of divers performing a series of heliox non-saturation dives.

Psychometric performance of 12 divers was evaluated throughout a series of 60-72-m in-water heliox non-saturation ('bounce') dives using a repeated-measures, within-subject design. Assessments were made onboard a dive tender, using a portable computerized battery within 30 min of the diver leaving the water, 2 h later, and on rest days. No significant decrement in performance was demonstrated either post-dive or throughout the series. Ten controls showed no alteration in performance due to environmental factors such as ship motion. The consistency of the results confirmed the suitability of this system for monitoring cognitive function during a series of potentially hazardous dives.

Adult↗
PubMed1990

Analysis of neurologic symptoms in deep diving: implications for selection of divers.

Eighteen professional divers (age range 24-33 yr, mean 28.3) participated in one simulated dive to 360 meters of seawater (msw) in a helium-oxygen (heliox) atmosphere with equal compression and decompression profiles. All divers were given an extensive neurologic examination before diving. Clinical neurologic symptoms observed during the dives were equilibrium disorder, sleep disturbances, fatigue, nausea, loose stools, stomach pain, tremor, mental disturbances, reduced appetite, and headache. Symptoms were scored individually by each diver. The symptoms were analyzed statistically by factor analysis, which grouped them into four factors. These symptoms are presumably related to functional disturbances in the brain stem and the cerebellum. Factor 3 symptoms (tremor, mental disturbances, reduced appetite) correlated significantly to a history of predive decompression sickness (P = 0.006) and to cerebral concussion (P = 0.023). Three divers were periodically unable to work at bottom due to equilibrium disorder, diarrhea, or nausea. One diver with mild polyneuropathy and slight cerebral atrophy as seen by computerized tomography and another diver with abnormal electroencephalography were periodically unable to work due to equilibrium disorder and nausea, respectively. We advocate that divers with signs of central or peripheral nervous system dysfunction should not be selected for deep diving.

Adult↗