SEARCH · Search PubMed

Results for “DIVING”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMed1994

Cardiovascular and pulmonary responses to breath-hold diving in humans.

Cardiovascular and pulmonary responses to breath-hold diving (breath holding, submersion, and compression) were investigated. In addition, the effects of transitions between dry conditions and head-out immersion during eupnea were studied. Surface breath holds at a large lung volume with relaxed respiratory muscles resulted in a positive esophageal (transthoracic) pressure and a reduced cardiac output. In contrast, the esophageal pressure (relative to ambient pressure) was decreased, and cardiac output was at least partially restored, when lung gas volume was reduced by compression during breath-hold diving. The increased cardiac output that accompanied eupneic transition from dry to immersed conditions was associated with a short-lasting increase of alveolar gas exchange, whereas the decreased cardiac output during immersion-to-dry transition was associated with a long-lasting decrease of alveolar gas exchange, both reflecting changes in the tissue gas stores of the body. Surface breath holds were associated with a decreased O2 uptake from the lung to the blood, and breath-hold dives were associated with a large transient increase of O2 uptake at depth which resulted in a restoration of the time-averaged O2 uptake to the eupneic control level: these changes reflected changes in tissue O2 stores. Compared to surface breath holds, breath-hold dives were associated with larger tissue retention of CO2 during breath holds, and prolonged recovery for CO2 elimination after breath holds. The distribution of pulmonary perfusion, as indicated by expirograms obtained immediately after breath holds, was made more homogeneous by submersion and the distribution was further improved by compression during breath-hold dives. All of these different effects on the gas exchange in breath-hold diving and in eupneic headout immersion can to a large extent be explained by associated changes in cardiac output in combination with redistributions of peripheral blood flow and venous blood volume. Thus, the different components of breath-hold diving have profound cardiovascular and pulmonary effects. Changes in the intrathoracic pressure and in the distribution of venous blood volume induce changes in cardiac output. All of these changes affect the temporal and spatial distributions of pulmonary perfusion and peripheral blood flow. Also, the circulatory changes affect the temporal and spatial distributions of alveolar gas exchange and of tissue gas stores of the body.

Adolescent↗

PubMed1994

Exercise effects on central venous nitrogen tensions after simulated non-decompression dives.

In five subjects we examined the effect of exercise on the pattern of central venous (right atrial) N2 tensions (PVN2) after ascent from simulated non-decompression dives. The dives consisted of exposure to air at 3 bar for 20 min with 10 min of exercise (workload 75 W) at depth to achieve near-complete N2 saturation of the muscles. After the dive the subjects rested or, on another day, exercised for 30 min (workload 100 W) starting 10 min after completing the ascent. Blood samples taken every 10 min until the 60th min and 90 min after the dive were analyzed for PVN2 using a manometric Van Slyke apparatus. The amount of N2 eliminated was estimated from the PVN2 by adapting the Fick principle. Immediately after the ascent, PVN2 were 950 +/- 39 and 942 +/- 27 mmHg, respectively, in the rest and experiment series. In the rest experiments PVN2 continuously decreased to 606 +/- 8 mmHg 90 min after the dive, remaining significantly higher (P < 0.05) than before the dive. Exercise caused the PVN2 to increase beyond the corresponding levels of the rest experiments (P < 0.05 at 20 and 30 min exercise). After the exercise PVN2 rapidly declined, reaching predive levels 60 min after the ascent. Exercise increased N2 elimination to 970 +/- 143 ml, whereas it had been 311 +/- 61 ml (P < 0.05) in the corresponding phase of the rest experiments. We conclude that if extensive supersaturation and bubble formation can be avoided, such as probably was the case in our shallow non-decompression dives, exercise after the ascent accelerates N2 elimination.

Adult↗

PubMed1993

Continuous pulse oximetry in the breath-hold diving women of Korea and Japan.

Arterial oxygen saturation during breath-hold diving has not previously been measured continuously. We devised a submersible, waterproof, backpack computer to continuously record heart rate, depth, and arterial oxygen saturation (SPO2) as determined by earlobe pulse oximetry. Our measurements showed that one assisted (Funado) diver had reduced SPO2 values immediately after surfacing from 22 dives which lasted 23-76 s, from a mean of 99 +/- 1% SPO2 to 96 +/- 3% SPO2. SPO2 returned to 97 +/- 2% within 15 s after surfacing (P < 0.05 surface value differs from predive base line). Four unassisted (Cachido) divers showed no significant reduction of mean predive SPO2 below 98 +/- 2% at any time during the dive or recovery period in 92 routine dives lasting from 15 to 44 s. Upon surfacing from diving, mean SPO2 was 98 +/- 2% and the mean SPO2 15 s after surfacing was 97 +/- 3% for the unassisted divers. Three Cachido divers were asked to dive and breath hold for as long as possible. Mean SPO2 at the conclusion of breath holding was 73% after an average dive and breath hold lasting 69 s.

Adult↗

PubMed1993

[Who may dive?].

There are no statutory regulations concerning sport diving or diving ability tests. Ability tests should only be performed by practitioners who are familiar with the physiology of diving. The requirements for diving are familiarity with the diving technique, basic knowledge of human body behaviour under water as well as a sound organism and a good psychic balance. There is no fixed age limit. Diving is even possible under certain circumstances in the case of some chronic illnesses (asthma, diabetes). The medical examination should focus on possible drug intake, on ear, nose and throat as well as on the cardiopulmonary and psychic state. The pathophysiological significance of selected illnesses for diving are described briefly. Relative and absolute contraindications are discussed.

Barotrauma↗

PubMed1993

Bubble formation and decompression sickness on direct ascent from shallow air saturation diving.

To find the minimum supersaturation pressure for detectable bubble formation and for contraction of decompression sickness (DCS), three shallow air saturation dives at the depth of 6 m, 7 m, and 8 m were performed. The ultrasonic M-mode method was used for detecting bubbles. The exposure period was 3 d for all dives. Ten subjects were compressed to both 6 m and 7 m, and nine subjects were compressed to 8 m. One bubble streak was shown in the 6-m dive group. A small number of bubbles were seen in four subjects in the 7-m dive. All subjects in the 8-m dive presented various amounts of bubbles. DCS was not observed in the 6-m and 7-m dives. On the other hand, in the 8-m dive, four subjects suffered from DCS and required recompression treatment. The minimum depth for detectable bubble formation was assessed at around 6 m and the direct ascent from saturation at 8 m seems to have a high risk of DCS.

Adult↗

PubMed1997

Scuba decompression illness and diving fatalities in an overseas military community.

A retrospective study of scuba decompression illness (DCI) and fatalities in the U.S. military community on Okinawa Island, Japan, was performed for 1989-95. Some 94 cases of diving DCI, including 10 cases of cerebral air-gas embolism (CAGE), and 9 diving fatalities were reported, for an annual incidence of 13.4 DCI events and 1.3 fatalities per 100,000 dives. The overall estimated incidence of scuba DCI was estimated to be 1/7400 dives, with an annual incidence of undeserved DCI of 1/37,300, and a fatality rate of 1/76,900. A review of treatment dives revealed a 10% overdiagnosis rate in cases treated for presumed DCI. A bimodal distribution of DCI accidents was observed for depths deeper or shallower than 24.6m/80FSW (feet of sea water). Increased risk of DCI in diving deeper than 24.6m/80FSW was associated with violations of no-decompression limits (NDL), while other risk factors were associated with diving to less than 24.6m/80FSW. NDL violations accounted for only 24/94 (26%) of all DCI accidents. Treatment of divers with hyperbaric oxygen (HBOT) led to complete recovery in 91% of cases, but of those divers requiring retreatment with HBOT, 67% had chronic residua of DCI. Selected illustrative and interesting cases are discussed.

Adult↗

PubMed2000

Dive Operator Use Patterns in the Designated No-Take Zones of the Florida Keys National Marine Sanctuary (FKNMS).

/ The Florida Keys National Marine Sanctuary (FKNMS), created by Congress in 1990, addressed the issue of resource protection partly by proposing 26 "no-take" zones. These areas, discussed in the 1995 Draft Management Plan, disallowed all extractive activities, and four of the zones also prohibited diving and snorkeling. Furthermore, the Draft Management Plan considered recreational carrying capacity, proposing that use densities be studied and eventually limited in high-use and sensitive areas. Conducted with 62 commercial dive operators from the Florida Keys in 1995-96, this study uses geographic information systems (GIS) to determine the extent of FKNMS zone use by dive operators, assess the regional importance of FKNMS zones to operators, and compare management strategies by which to allow use while minimizing impacts to the coral reef resource. Dive operators took almost 70% of their total trips and 77% of their total divers to FKNMS zones in 1995. Although zone use is generally related to the proximity of dive locations, dive operators do rely disproportionately on single sites in certain regions. The resulting profiles demonstrate that management strategies need to consider disproportionate use, as well as the average number of users per trip, to effectively protect the region's environmental resources. In addition to implementing a carrying capacity plan, the FKNMS should consider a limited-entry system for dive operators.

Journal Article↗

PubMed1994

DIVING ENERGETICS IN LESSER SCAUP (AYTHYTA AFFINIS, EYTON)

Mechanical and aerobic energy costs of diving were measured simultaneously by closed-circuit respirometry in six lesser scaup Aythya affinis Eyton (body mass=591±30 g) during bouts of voluntary feeding dives. Durations of dives (td=13.5±1.4 s) and surface intervals (ti=16.3±2.2 s) were within the normal range for ducks diving to 1.5 m depth. Mechanical power output (3.69±0.24 W kg-1) and aerobic power input (29.32±2.47 W kg-1) were both higher than previous estimates. Buoyancy was found to be the dominant factor determining dive costs, contributing 62 % of the mechanical cost of descent and 87 % of the cost of staying at the bottom while feeding. Drag forces, including the contribution from the forward-moving hindlimbs during the recovery stroke of the leg-beat cycle, contributed 27 % and 13 % of the mechanical costs of descent and feeding, respectively. Inertial forces created by net acceleration during descent contributed approximately 11 % during descent but not at all during the feeding phase. Buoyant force at the start of voluntary dives (6.2±0.35 N kg-1) was significantly greater than that measured in restrained ducks (4.9±0.2 N kg-1). Loss of air from the plumage layer and compression due to hydrostatic pressure decreased buoyancy by 32 %. Mechanical work and power output were 1.9 and 2.4 times greater during descent than during the feeding phase. Therefore, energetic costs are strongly affected by dive-phase durations. Estimates by unsteady and steady biomechanical models differ significantly during descent but not during the feeding phase.

Journal Article↗

PubMed1988

Use of the maximum likelihood method in the analysis of chamber air dives.

The method of maximum likelihood was used to evaluate the risk of decompression sickness (DCS) for selected chamber air dives. The parameters of two mathematical models for predicting DCS were optimized until the best agreement (as measured by maximum likelihood) corresponding to the observed DCS incidents from a series of dives was attained. The decompression data used consisted of 800 man-dives with 21 incidents of DCS and 6 occurrences of marginal symptoms. The first model investigated was based on a nonlinear gas exchange in a series arrangement of four compartments. The second model was based on a monoexponential gas exchange in a parallel arrangement of two compartments. The overall statistical success in describing the 800 man-dives was quite similar for the two models. Predictions of safety for dives not part of the original data differed for the models due to differences in gas kinetics. For short, no-decompression dives, the series arrangement of compartments predicted a lower incidence of DCS. These predictions were more consistent with the outcome of subsequent testing than were predictions of the parallel compartment model. Predictions of the series arrangement model were also similar to those of a single-compartment, two-exponential model that was evaluated with over 1700 man-dives by the U.S. Navy.

Decompression Sickness↗

PubMed1998

Effects of lung volume and involuntary breathing movements on the human diving response.

The effects of lung volume and involuntary breathing movements on the human diving response were studied in 17 breath-hold divers. Each subject performed maximal effort apnoeas and simulated dives by apnoea and cold water face immersion, at lung volumes of 60%, 85%, and 100% of prone vital capacity (VC). Time of apnoea, blood pressure, heart rate, skin capillary blood flow, and fractions of end-expiratory CO2 and O2 were measured. The length of the simulated dives was the shortest at 60% of VC, probably because at this level the build up of alveolar CO2 was fastest. Apnoeas with face immersion at 100% of VC gave a marked drop in arterial pressure during the initial 20 s, probably due to high intrathoracic pressure mechanically reducing venous return. The diving response was most pronounced at 60% of VC. We concluded that at the two larger lung volumes both mechanical factors and input from pulmonary stretch receptors influenced the bradycardia and vasoconstriction, resulting in a nonlinear relationship between the breath-hold lung volume and magnitude of the diving response in the near-VC range. Furthermore, the involuntary breathing movements that appeared during the struggle phase of the apnoeas were too small to affect the diving response.

Adult↗

PubMed1986

The human dive reflex: an experimental, topographical and physiological analysis.

This study examined the eliciting conditions, response topography and autonomic nervous system (ANS) control of the dive reflex as evoked in humans. Twenty-four subjects received eight trials in each of the three treatment conditions: breath holding without face immersion (BH); face immersion without breath holding (FI); and the "full dive" FIBH condition. It was the combination of both FI and BH in 23 +/- 0.5 degrees C water that was necessary to elicit the dive reflex. A precise topographical analysis differentiated the FIBH condition from the FI and BH control conditions in terms of the emergence of a secondary component initiated approximately 12 seconds after trial onset. During this secondary component, augmentation of bradycardic (mean = 16.3 bpm) and digital vasoconstrictive (mean = -24.9%) responses were maintained throughout the duration of the 40-second dive. A joint consideration of the heart rate and the T-wave amplitude measures as indices of the action of both branches of the ANS suggested that the dive reflex involves concurrent sympathetic and parasympathetic activation. A potential conditioning application of the dive reflex for countering paroxysmal supraventricular tachycardia was discussed.

Adolescent↗

PubMed2005

Diving injuries of the cervical spine in amateur divers.

BACKGROUND CONTEXT: Diving injuries are the cause of potentially devastating trauma, primarily affecting the cervical spine. PURPOSE: Our purpose was to describe our experience with diving injuries treatment. STUDY DESIGN: Retrospective review. PATIENT SAMPLE: Twenty patients with diving injuries. OUTCOME MEASURES: Using the American Spinal Injury Association (ASIA) impairment scales as the primary outcome measure, the patients' neurological status before and after treatment was assessed. In this way we were able to draw conclusions about neurological improvement or deterioration in response to conservative or operative treatment. METHODS: We retrospectively reviewed 20 patients with diving injuries of the cervical spine who were admitted to our institute over a 34-year period from 1970 until 2004. RESULTS: The typical patient profile was of a young, healthy, athletic male who suffered an injury to the cervical spine after diving into shallow water. The number of cases corresponds to 2.6% of all admitted cervical spine injuries. All injures occurred between May and September. The most commonly fractured vertebrae were C5 and C6. Four patients were treated operatively and 16 conservatively. The indications for surgical treatment were posttraumatic instability and persistent neurological deficit. The mean follow-up of the patients was 17 years. Five patients died within the first month of their hospitalization and 1 patient died 1 year after his injury. Of the 14 patients who were available for follow-up 5 years past injury time, 6 improved neurologically and 8 remained unchanged in relation to their neurology upon admission. Of the 11 patients who were available for follow-up 10 years past injury time, 9 remained neurologically unchanged, 1 deteriorated, and 1 improved in relation to their neurology in the 5-year follow-up. CONCLUSION: Diving injuries of the cervical spine demonstrate high mortality and morbidity rates. Recovery depends on the severity of the initial neurological damage. Conservative treatment is justified in specific patients and can lead to improvement of the initial neurological deficit.

Adolescent↗

PubMed1999

The basics of competitive diving and its injuries.

This article reviews the history of competitive springboard and platform diving, the basic rules of competition, and the epidemiology and pathomechanics of diving injuries, with reference to the specific parts of the dive. Injuries are more commonly associated with the entry phase of the dive, and are more frequently associated with back and reverse dives, and with platform rather than springboard diving. The most frequently injured areas are the wrist, shoulder, and lumbar spine. It is crucial that treating medical professionals understand the physical demands of the sport and the pathogenesis of injury to affect successful treatment and prevention strategies, and to determine safe return to participation after injury.

Athletic Injuries↗

PubMed2000

Body size and skeletal muscle myoglobin of cetaceans: adaptations for maximizing dive duration.

Cetaceans exhibit an exceptionally wide range of body mass that influence both the capacities for oxygen storage and utilization; the balance of these factors is important for defining dive limits. Furthermore, myoglobin content is a key oxygen store in the muscle as it is many times higher in marine mammals than terrestrial mammals. Yet little consideration has been given to the effects of myoglobin content or body mass on cetacean dive capacity. To determine the importance of myoglobin content and body mass on cetacean diving performance, we measured myoglobin content of the longissimus dorsi for ten odontocete (toothed whales) and one mysticete (baleen whales) species ranging in body mass from 70 to 80000 kg. The results showed that myoglobin content in cetaceans ranged from 1.81 to 5.78 g (100 g wet muscle)(-1). Myoglobin content and body mass were both positively and significantly correlated to maximum dive duration in odontocetes; this differed from the relationship for mysticetes. Overall, the combined effects of body mass and myoglobin content accounts for 50% of the variation in cetacean diving performance. While independent analysis of the odontocetes showed that body mass and myoglobin content accounts for 83% of the variation in odontocete dive capacity.

Adaptation, Physiological↗

PubMed2006

Otolaryngological requirements for recreational self-contained underwater breathing apparatus (SCUBA) diving.

Recreational self-contained underwater breathing apparatus (SCUBA) diving continues to grow in popularity. Medical requirements to be 'fit to dive' vary throughout the world, from self-certification to a full medical examination prior to training. This review discusses the relative merits of the most commonly used guidelines for recreational SCUBA diving, with reference to common diving-related otorhinolaryngological conditions. Areas of controversy, such as fitness to dive after rhinological and otological surgery, are discussed. The authors suggest that a unified approach from the various recreational SCUBA diving organizations involved would aid in clarification for divers and physicians alike. The difficulties in achieving such a unified approach, however, should not be underestimated.

Barotrauma↗

PubMed2003

[Lung edema in scuba diving].

The management of a diving-related emergency is frequently a great challenge for an emergency physician without a special diving medicine training or experiences. Almost every physician knows something about the medical therapy of diving-related accidents which are combined with a barotrauma or a decompression sickness. But there are still some rare symptoms and organ affections of diving-related emergencies which are unknown in common. In consideration of the present case of an acute diving-related lung edema we discuss the different reasons and differential diagnosis of diving emergencies.

Diving↗

PubMed2006

Pulmonary function in children after a single scuba dive.

This study evaluated the respiratory effects of a single dive in children. Eighteen young divers and 18 controls participated in our study (age range: 9 - 13 years). Volumes and expiratory flow rates were measured 20 minutes before and 10 minutes after one air dive (3 meters, 25 minutes). Before the dive, no differences were noted regarding pulmonary parameters. Ten minutes after the dive, decreases were noted in forced expiratory volume in 1 s (FEV1) and maximal voluntary ventilation (- 8 %, - 5.3 %, respectively; p < 0.01), peak expiratory flow, maximal expiratory flow rates at 50 % of FVC (MEF(50 %)) and MEF(25 %), forced mid-expiratory flow rate (FEF(25 - 75 %)), and FEV1/FVC(- 5.9 %, - 14.3 %, - 21.4 %, - 4.2 %, - 3.5 %, respectively; p < 0.05). The respiratory pattern observed 10 minutes after a single dive to three meters indicated airway narrowing. However, no association between diving experience and lung function was obtained.

Age Factors↗

PubMed2002

Hurdle preflight in springboard diving: a case of diminishing returns.

Attempts to increase dive height by introducing a period of flight in the final approach step preceding the hurdle of dives from forward and reverse groups were investigated. One study involved 11 collegiate-level divers experienced in both traditional and hurdle preflight techniques. In a second study, dives executed by 9 national-level women were compared. Dives with a hurdle preflight had shorter final approach steps and greater hurdle flight durations. Flight time differences in favor of hurdle preflight techniques diminished from final approach step through hurdle flight to dive flight. Although the collegiate-level divers had longer dive flight times when using a hurdle preflight, it was suggested that the costs of these techniques may outweigh their potential benefits.

Adult↗