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At least 451 records · Page 25Linked to original sources
PubMed2000

Hyperbaric stress during saturation diving induces lymphocyte subset changes and heat shock protein expression.

To clarify the cellular responses and biochemical markers of hyperbaric stress, we investigated heat shock protein (hsp) expression and subset changes of human peripheral blood lymphocytes during saturation diving. Five healthy male subjects underwent a 39-day saturation dive to the maximal storage pressure of 4.1 MPa [400 meters of sea water (msw)]. During the saturation dive, lymphocyte subset changes were detected using a flow cytometer, and increased expressions of hsp 72/73 and hsp 27 were observed by Western blot analysis. Lymphocyte subset changes included a decrease in CD4:CD8 ratio and in the fraction of CD4+ T cells as well as an increase in NK cells, especially during the 400-msw bottom phase. An increased expression of hsp 27 compared to hsp 72/73 was obvious, especially during the hold period at 100 msw. These results suggest that changes in lymphocyte subsets and hsp expression are useful markers for stress responses during saturation diving. These changes may also be useful for testing the barotolerance of divers for saturation diving.

Biomarkers↗
PubMed1976

Left-ventricular performance in man during breath-holding and simulated diving.

We measured left-ventricular (LV) systolic time intervals (STI) to determine whether breath-holding and simulated diving evoke a depression of LV performance in man similar to that previously demonstrated in natural divers. Records of STI were obtained by a noninvasive procedure in 15 adult males who had breath-holding diving experience during supine rest, at 30 and 60 s of simple breath-holding (BH) and at 30 and 60 s of BH combined with cold, wet facial stimulation (FS). Changes in both BP and HR during FS reflected cardiovascular behavior typical of simulated diving. The isovolumic contraction period increased 13% and 31% after 60 s of BH and FS, respectively. LV ejection time shortened by 30 ms during BH and by 37 ms during FS. These measurements of STI represent the first description of cardiac cycle components during the human diving response. The alterations in STI suggest that a reduction in LV performance, as seen by a decreased rate of preejection pressure development and a diminished stroke volume, had occurred during the apneic maneuvers. In addition, there was a trend in these measures indicating that FS potentiated the response over that which occurred during BH. Thus, it appears that man exhibits a depression of LV performance during simulated diving similar to that found in natural divers.

Adult↗
PubMed1996

Saturation diving as a submarine rescue tool.

The U.S. Navy Submarine Rescue Diving and Recompression System (SRDRS) uses saturation diving to provide human intervention at the hatch of a disabled submarine. The system incorporates the basic elements of traditional saturation diving platforms to provide life support to divers at the worksite as well as in a decompression chamber in between work assignments. The demands of the submarine rescue mission require that the system provide quick response to an emergency virtually anywhere in the world. To answer these demands, SRDRS uses a mixture of state-of-the-art diving technologies and traditional approaches to life support in a quickly mobilized, easily transportable diving system capable of operating in extremely harsh environments.

Air Conditioning↗
PubMed1999

Advanced dive monitoring system.

The US Navy supports deep diving operations with a variety of mixed-gas life support systems. A systems engineering study was conducted for the Naval Experimental Dive Unit (Panama City, FL) to develop a concept design for an advanced dive monitoring system. The monitoring system is intended primarily to enhance diver safety and secondarily to support diving medicine research. Distinct monitoring categories of diver physiology, life support system, and environment are integrated in the monitoring system. A system concept is proposed that accommodates real-time and quantitative measurements, noninvasive physiological monitoring, and a flexible and expandable implementation architecture. Human factors and ergonomic design considerations have been emphasized to assure that there is no impact on the diver's primary mission. The Navy has accepted the resultant system requirements and the basic design concept. A number of monitoring components have been implemented and successfully support deep diving operations.

Body Temperature↗
PubMed1999

Gastro-esophageal barotrauma in diving: similarities with Mallory-Weiss syndrome.

Mallory-Weiss syndrome (MWS) is a well-defined entity in clinical medicine. However, the development of such a syndrome as a result of overpressure barotrauma of the stomach after repeated shallow-water scuba dives is rare. Also rare is the delayed onset of the MWS, approximately 20 hours after the dives. The causes of development of MWS in connection with scuba diving are discussed. The main causes seem to be the repeated changes of gas volume in the stomach with subsequent pressure forces toward the cardia in the course of repeated dives. The possibility of serious diving accident due to overpressure barotrauma of gastro-intestinal system is also pointed out.

Adult↗
PubMed2003

Self-reported headache during saturation diving.

INTRODUCTION: Some commercial divers have claimed that headache is a frequent symptom related to decompression following a saturation dive, but due to lack of systematic reporting there is limited knowledge of the incidence and clinical characteristics of such headaches. METHODS: During 2001, a questionnaire was distributed to divers participating in offshore saturation diving operations on the Norwegian continental shelf. Two major diving contractors participated. The survey allowed anonymous self-reporting of past and present problems with headache; pain intensity was indicated daily on a visual analog scale (VAS) from 0 to 10. Of 95 divers, 56 participated and 67 saturations were registered. RESULTS: The divers estimated a higher frequency of headaches in connection to saturation diving than in everyday life (p < 0.001). One third of the divers reported experiencing headache after they finished decompression. There was a significant increase in reports of headache on the last day of decompression (p = 0.03) and on the first day post-saturation (p < 0.001) compared with the start of decompression. Median headache duration was 6 h (range 1-84 h) and median pain score estimated on a VAS was 2.5 (range 0.1-7.8), equivalent to moderate intensity. CONCLUSIONS: Headache incidence is greater in divers during saturation diving than in everyday life. The increase is correlated to the last phase of decompression and the post-saturation period. No specific cause(s) of the headache could be identified, but we discuss possible explanations.

Adult↗
PubMed2003

Autonomic nervous activity and stress hormones induced by hyperbaric saturation diving.

This study describes the changes in autonomic nervous activity and stress hormones during a hyperbaric saturation dive up to 4.1 MPa in six subjects. Their autonomic nervous activity was assessed by a power spectrum analysis of heart rate variability (HRV). The levels of plasma epinephrine (E) and norepinephrine (NE), and those of salivary chromogranin A and cortisol, were compared with the pre-dive control levels. Restrained activity of the cardiac vagal nerve was recognized in the early post-dive period by a decrease in high frequency power and by the standard deviation of the HRV. By contrast, enhanced activity of sympathetic nerve was recognized in the early post-dive period by an elevated plasma E, and also in the late 3.1 MPa, 4.1 MPa, and post-dive periods by elevated plasma NE. The levels of plasma E and NE were the most sensitive indicators of sympathetic nervous activity. A joint utilization of HRV parameters with stress hormones may be an effective means of estimating the adaptive responses between hyperbaric and normobaric environments.

Adult↗
PubMed2003

Risk of decompression sickness during exposure to high cabin altitude after diving.

BACKGROUND: Postdive altitude exposure increases the risk of decompression sickness (DCS). Certain training and operational situations may require U.S. Special Operations Forces (SOF) personnel to conduct high altitude parachute operations after diving. Problematically, the minimum safe preflight surface intervals (PFSI) between diving and high altitude flying are not known. METHODS: There were 102 healthy, male volunteers (34 +/- 10 [mean +/- SD] yr of age, 84.5 +/- 13.8 kg weight, 26.2 +/- 4.2 kg x m(-2) BMI) who completed simulated 60 fsw (feet of seawater)/60 min air dives preceding simulated 3-h flights at 25,000 ft to study DCS risk as a function of PFSI. Subjects were dry and at rest throughout. Oxygen was breathed for 30 min before and during flight in accordance with SOF protocols. Subjects were monitored for clinical signs of DCS and for venous gas emboli (VGE) using precordial Doppler ultrasound. DCS incidence was compared with Chi-squared; VGE onset time and time to maximum grade with one-way ANOVA (significance at p < 0.05). RESULTS: Three cases of DCS occurred in 155 subject-exposures: 1/35 and 0/24 in 2 and 3 h flight-only controls, respectively; 0/23, 1/37, and 1/36 for 24, 18, and 12 h dive-PFSI-flight profiles, respectively. DCS risk did not differ between profiles (chi2 [4] = 1.33; crit = 9.49). VGE were observed in 19% of flights. Neither VGE onset time nor time to max grade differed between profiles (82 +/- 38 min [p = 0.88] and 100 +/- 40 min [p = 0.68], respectively). CONCLUSION: Increased DCS risk was not detected as a result of dry, resting 60 fsw/60 min air dives conducted 24-12 h before a resting, 3-h oxygen-breathing 25,000 ft flight (following 30 min oxygen prebreathe). The current SOF-prescribed minimum PFSI of 24 h may be unnecessarily conservative.

Adult↗
PubMed2003

Pulmonary edema following closed-circuit oxygen diving and strenuous swimming.

Acute pulmonary edema may be induced by diving and strenuous swimming. We report the case of a diver using closed-circuit, scuba equipment who developed acute dyspnea, hemoptysis, and hypoxemia following a dive in 18 degreesC (64.4 degrees F) water and physical exertion during the swim back to shore. With the growing popularity of recreational scuba diving, emergency physicians are liable to be faced with increasing numbers of diving-related medical problems. Diving-induced pulmonary edema should be included in the differential diagnosis of acute hypoxemia, sometimes accompanied by acid-base abnormalities, when this is seen in a diver.

Adult↗
PubMed1992

Renal responses during a dry saturation dive to 450 msw.

Four subjects were compressed to a simulated depth of 450 msw (46 bar) for 37 days in the main research chamber of the German underwater simulator diving facility at the GKSS Research Center, Geesthacht. The ambient gas was trimix. Urine was collected at 0700, 1300, and 1900 h each day for analysis of Na+, K+, volume, osmolality, and creatinine. Urine, antidiuretic hormone (ADH), and aldosterone were analyzed separately. Daily fluid, Na+, and K+ intake were analyzed throughout the dive. The aim of the investigation was to confirm the existence of a diuresis and natriuresis which had been observed in earlier saturation dives to 31 atm abs using He-O2. A significant diuresis was observed during compression despite a decrease in fluid intake. After compression the diuresis decreased somewhat but remained significantly above precompression control levels during the entire hyperbaric exposure. No significant change in fluid intake was observed. Daily Na+ and K+ excretion increased significantly during compression, which was accompanied by a significant increase in nocturnal excretion of Na+ and K+. Daily intake of Na+ and K+ decreased throughout the dive. Daily urine ADH decreased immediately upon compression and was associated with a parallel decrease in urine osmolality. In contrast, urinary aldosterone excretion exhibited no change during the dive despite the increase in Na+ and K+ excretion and decrease in Na+ intake.

Aldosterone↗
PubMed2003

[Asthma and scuba diving].

In scuba diving, the density of the gases supplied increases with depth. During ascent, overinflation of the lungs is avoided by exhalation. In case of airway obstruction, the theoretical risk of pulmonary barotrauma and drowning increases. For this reason, asthma has been considered as a contraindication to scuba diving. This recommendation is often ignored and many people with asthma dive, apparently without problems. Certifying that an asthmatic patient is fit to dive remains a controversial and difficult matter. In case of mild intermittent asthma, scuba diving seems possible when the pulmonary function test is normal and the patient is asymptomatic, including during exercise and exposure to cold air. The asthmatic diver should be fully informed of the risks incurred and should notify his or her informed-consent to the physician.

Asthma↗
PubMed2004

[Before going on a diving holiday--consider this].

A prerequisite for all those who go in for the sport of scuba diving is mental and physical fitness. This must be checked within the framework of an examination for diving fitness before first taking up the sport, and should be rechecked every one to three years. For fitness for diving, not only lung function, ECG and tubal function need to be normal--the psychological profile of the holiday maker also plays an important role under water. For he or she must be able rapidly and reliably to recognize a dangerous situation and to react to it appropriately. Thorough training and the compliance with the rules of diving offer protection from many of the risks of this underwater sport--for example, problems with the ears or sinuses can be avoided. The most common cause of fatal diving accidents is a barotrauma of the lung with rupture of the alveoli on ascending.

Aerospace Medicine↗
PubMedDate not supplied

Scuba diving with diabetes mellitus--the UK experience 1991-2001.

OBJECTIVES: To survey the outcomes and practises of divers with diabetes mellitus. METHODS: Diabetic persons wishing to learn to scuba-dive or established divers who have diabetes mellitus in the UK are requested to fill in a detailed questionnaire annually. Divers are asked to provide basic epidemiological information and general diving history. Data provided by the diver's diabetic physician provided independent evidence of the diver's medical status. These data are recorded and analysed. RESULTS: Data have been gathered from 323 diabetic divers (269 male, 54 female) and 8,760 dives have been recorded over 11 years. Two fatalities were reported, both in non-insulin dependent divers. One incident of hypoglycaemia underwater in an insulin dependent diabetic diver has been reported. CONCLUSIONS: This survey showed that in the group of well-controlled diabetic divers studied, there were no serious problems due to hypoglycaemia when they dived. Long-term complications of diabetes must be excluded before a diabetic diver may be permitted to dive.

Adult↗
PubMed2005

[Medical aspects of diving in the tropics].

Scuba diving vacations in tropical surroundings belong to the repertoire of most divers. In addition to carefully making travel plans and taking care of the necessary vaccinations and appropriate malaria prophylaxis, the following points also must be observed. The flight itself affects diving safety. In particular, a too short time interval between diving and the return flight can lead to decompression problems. Because most of the diving areas are reached by ship, many divers need a prophylaxis against motion sickness. Moreover, external otitis occurs more frequently while diving in the tropics. Finally, there is potential danger from the sea inhabitants, primarily from scorpion fishes, Portuguese Man-of-Wars, box jellyfishes as well as cone snails.

Animals↗
PubMedDate not supplied

Diving behaviour and decompression sickness among Galapagos underwater harvesters.

Diving conditions, dive profiles, vascular bubbles, and symptoms of decompression sickness (DCS) in a group of Galapagos commercial divers are described. They harvest sea cucumbers from small boats with surface supplied air (hookah). Dive profiles for 12 divers were recorded using dive loggers, and bubble formation was measured in the pulmonary artery. DCS symptoms were assessed by interview. A total of 380 immersions were recorded over a nine day period. The divers did on average 6.3 immersions per day, in a yo-yo pattern. Mean overall depth was 34.5 FSW. Maximum recorded depth was 107 FSW. Average bottom time per day per diver was 175 minutes. 82 % of all ascents exceeded the recommended maximum ascent rate of 30 FSW/ min. High bubble grades were observed on six occasions, but the test was unreliable. Muscle and joint pain was reported on five occasions, in three different divers. Symptoms were typically managed by analgesics, in-water recompression or not at all. The divers were extremely reluctant to seek professional help for DCS symptoms, mostly due to the high costs of treatment. We conclude that the fishermen dive beyond standard no-decompression limits, and that DCS symptoms are common.

Adolescent↗
PubMed1991

Decrease in the single-breath diffusing capacity after saturation dives.

Before and after saturation dives, we measured lung volumes and diffusing capacity (DL(CO)/V(A] with a single-breath method on 12 divers (6 divers per dive) who participated in 300-msw saturation dives (total dive time of 15 days with P(O)2 = 0.42 atm abs) and on 6 divers who were engaged in a 320-msw saturation dive (6 days of bottom time with P(O)2 = 0.42 atm abs and 12 days of total decompression time with P(O)2 = 0.495 atm abs. In all divers, vital capacity right after surfacing did not significantly decrease compared with predive values. In the 300-msw saturation divers after surfacing, DL(CO)/V(A) adjusted for hemoglobin (Hb) changes did not significantly decrease, but in the 320-msw saturation divers Hb-adjusted DL(CO)/V(A) was significantly (P less than 0.001) decreased by 0.70 (mean) +/- 0.21 (SD) (ml.min(-1).mmHg(-1).liter(-1]. These observations indicate that the diffusing capacity is a more sensitive index of pulmonary oxygen toxicity than vital capacity that is traditionally used, and that oxygen partial pressure less than 0.5 atm abs can induce a decrease in pulmonary function.

Diving↗
PubMed1990

Nitrogen partial pressures in man after decompression from simulated scuba dives at rest and during exercise.

In 5 subjects arterial and central venous nitrogen partial pressures (PN2) were measured after decompression from a chamber dive following a decompression schedule for scuba diving. The simulated dives consisted of exposure to air at 6 bar for 30 min corresponding to a depth of 50 m. Afterward the subjects were decompressed with decompression stops at 2.5, 2.2, 1.9, 1.6, and 1.3 bar with a total decompression time of 67 min. In 3 of the subjects the measurements were repeated after they had exercised (workload 75 W) during bottom time. Immediately after decompression and every 40 min until Minute 240 arterial and central venous blood samples were analyzed for PN2 using a manometric Van Slyke apparatus. Venous PN2 remained elevated until 160 min after decompression, indicating still incomplete nitrogen washout for at least 2 h after decompression had been accomplished. We did not find any difference in PN2 values after decompression from dives at rest and after exercise. Applying a computer program based on a wide range of theoretical tissue half-times nitrogen elimination proved to be consistent with Haldanian theories when using our decompression profile. Our data confirm that nitrogen elimination is prolonged after decompression from simulated dives at rest and after exercise.

Adult↗
PubMed1988

Change in plasma amino acid concentrations during breath-hold diving at high altitude.

We studied the plasma concentration of various amino acids in 6 Italian sport divers in Italy and at approximately 4,500 m altitude in Peru; 6 Peruvian inhabitants were examined for comparison. We attempted to create a situation of pronounced hypoxia in muscles by breath-hold diving at altitude. The diving reflex diverts blood away from muscles while diving increases central oxygen tension and prevents loss of consciousness. Differences in certain amino acids, probably related to diet, were noted between Italy and Peru. Increases in concentration of plasma alanine and some branched-chain amino acids occurred after breath-hold diving. These changes were similar to those seen after prolonged hard exercise, even though physical work was low. Hypoxia in muscles, common during hard work and during breath-hold diving at altitude, might thus be the stimulus for amino acid release from working muscles.

Adult↗