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PubMed1982

Hormonal changes and enforced diving in the harbor seal Phoca vitulina. II. Plasma catecholamines.

Plasma epinephrine and norepinephrine concentrations were measured in five harbor seals, Phoca vitulina, during a control period, during a 6-min dive, and during a 30-min postdiving recovery period. Measurements were performed with and without prior glucose administration. Control epinephrine concentrations [189 +/- 118 (SD) pg/ml] and norepinephrine concentrations (340 +/- 191 pg/ml) were similar to resting values in humans. During diving there are dramatic increases in both epinephrine and norepinephrine concentrations, which returned to control values by 30 min of the postdiving recovery period. A similar pattern was found after glucose infusion. The increased catecholamines were not the primary mechanism responsible for arterial constriction during the dive. Persistent diving bradycardia suggests obliteration of the chronotropic effects of catecholamines during the dive. An unchanged stroke volume suggests obliteration of the inotropic effects of catecholamines during the dive. Catecholamines do not appear to be involved in postdiving hyperglycemia and hyperglucogenemia. Neither the regulatory role of increased catecholamines nor the physiological function of increased catecholamines was apparent from the studies. However, dramatic increases in plasma catecholamines during diving appear to be an important component of the hormonal response to prolonged diving in aquatic mammals.

Animals↗
PubMed1982

Role of central and peripheral chemoreceptors in diving responses of ducks.

Using techniques of vascular isolation and subsequent perfusion we have investigated the effects of altering blood gas tensions, in the cerebral and carotid body circulations, on some cardiovascular responses to diving in unanesthetized ducks. After denervating the right carotid body, perfusion of the innervated left carotid body with hyperoxic blood significantly reduced diving bradycardia and reduced the increase in hindlimb vascular resistance (HLVR) in 1-min dives compared with dives in which the innervated carotid body was autoperfused. Denervation of systemic arterial baroreceptors reduced the fall in heart rate (HR) and increased the rise in HLVR in all dives. Cross-perfusion of the head, from a donor with blood of normal blood gas tensions, did not significantly affect HR or HLVR in 2-min dives compared with dives in which the head was autoperfused. however, cross-perfusing the cerebral circulation with blood of elevated PaCO2 caused significantly greater increases in HLVR than when high PaCO2 only affected the peripheral circulation. We conclude that peripheral chemoreceptors cause virtually all the bradycardia in the later stages of a dive but only about one-half the increase in HLVR, a significant contribution comes from the stimulation of central chemoreceptors with blood of high PaCO2.

Animals↗
PubMed1983

Renal glomerular filtration rate and hepatic blood flow during voluntary diving in Weddell seals.

Renal and hepatic function were studied during voluntary dives in Weddell seals by measuring the clearance rate of inulin and indocyanine green (ICG). Inulin is cleared exclusively by the kidneys and measures renal glomerular filtration rate (GFR). ICG is cleared by the liver and is blood flow dependent at concentrations used. Studies were conducted from a portable hut with a trapdoor placed over an isolated hole in the sea ice near McMurdo Station, Antarctica. An intravertebral extradural catheter was inserted percutaneously under light anesthesia in subadult seals weighing 130-200 kg. When released into the ice hole, the seals made voluntary dives, but always had to return to breathe. Serial blood samples were taken after single injections of inulin and ICG and analyzed within 24 h. The mean half time (t 1/2) for inulin clearance while resting at the surface was 27.3 +/- 13.0 min (n = 43) and the mean t 1/2 for ICG clearance was 18.3 +/- 7.3 min (n = 23). The mean resting GFR was 3.6 ml X min-1 X kg-1 (range 3.2-3.9, n = 3). Inulin and ICG clearance rates did not change from resting levels during dives shorter than the seal's aerobic dive limit (ADL). Inulin clearance decreased over 90% during dives longer than the ADL, but there was no significant reduction in ICG clearance during dives lasting up to 23 min. It appears that normal renal GFR and hepatic blood flow continue during natural aerobic dives. During dives that exceed the ADL, GFR is reduced but hepatic blood flow may be maintained.

Animals↗
PubMed1990

Splenic contraction during breath-hold diving in the Korean ama.

Major increases of hemoglobin concentration and hematocrit, possibly secondary to splenic contraction, have been noted during diving in the Weddell seal. We sought to learn whether this component of the diving response could be present in professional human breath-hold divers. Splenic size was measured ultrasonically before and after repetitive breath-hold dives to approximately 6-m depth in ten Korean ama (diving women) and in three Japanese male divers who did not routinely practice breath-hold diving. Venous hemoglobin concentration and hematocrit were measured in nine of the ama and all Japanese divers. In the ama, splenic length and width were reduced after diving (P = 0.0007 and 0.0005, respectively) and calculated splenic volume decreased 19.5 +/- 8.7% (mean +/- SD, P = 0.0002). Hemoglobin concentration and hematocrit increased 9.5 +/- 5.9% (P = 0.0009) and 10.5 +/- 4% (P = 0.0001), respectively. In Japanese male divers, splenic size and hematocrit were unaffected by repetitive breath-hold diving and hemoglobin concentration increased only slightly over baseline (3.0 +/- 0.6%, P = 0.0198). Splenic contraction and increased hematocrit occur during breath-hold diving in the Korean ama.

Adult↗
PubMed1995

Myoglobin saturation in free-diving Weddell seals.

Although the consumption of myoglobin-bound O2 (MbO2) stores in seal muscles has been demonstrated in seal muscles during laboratory simulations of diving, this may not be a feature of normal field diving in which measurements of heart rate and lactate production show marked differences from the profound diving response induced by forced immersion. To evaluate the consumption of muscle MbO2 stores during unrestrained diving, we developed a submersible dual-wavelength laser near-infrared spectrophotometer capable of measuring MbO2 saturation in swimming muscle. The probe was implanted on the surface of the latissimus dorsi of five subadult male Weddell seals (Leptonychotes weddelli) released into a captive breathing hole near Ross Island, Antarctica. Four seals had a monotonic decline of muscle O2 saturation during free diving to depths up to 300 m with median slopes of -5.12 +/- 4.37 and -2.54 +/- 1.95%/min for dives lasting < 17 and > 17 min, respectively. There was no correlation between the power consumed by swimming and the desaturation rate. Two seals had occasional partial muscle resaturations late in dives, indicating transfer of O2 from circulating blood to muscle myoglobin. Weddell seals partially consume their MbO2 stores during unrestrained free diving.

Animals↗
PubMed2004

Response to CO2 in novice closed-circuit apparatus divers and after 1 year of active oxygen diving at shallow depths.

Elevated arterial Pco(2) (hypercapnia) has a major effect on central nervous system oxygen toxicity in diving with a closed-circuit breathing apparatus. The purpose of the present study was to follow up the ability of divers to detect CO(2) and to determine the CO(2) retention trait after 1 year of active oxygen diving with closed-circuit apparatus. Ventilatory and perceptual responses to variations in inspired CO(2) (range: 0-5.6 kPa, 0-42 Torr) during moderate exercise were assessed in Israeli Navy combat divers on active duty. Tests were carried out on 40 divers during the novice oxygen diving phase (ND) and the experienced oxygen diving phase. No significant changes were found between the two phases for the minimal mean inspired Pco(2) that could be detected. The mean (with SD in parentheses) end-tidal Pco(2) during exposure to an inspired Pco(2) of 5.6 kPa (42 Torr) was significantly higher in the novice diving phase than in the experienced diving phase [8.1 kPa (SD 0.7), 62 Torr (SD 5) and 7.8 kPa (SD 0.6), 59 Torr (SD 4), respectively; P < or = 0.001]. One year of shallow oxygen diving activity with a closed-circuit apparatus does not affect the ability to detect CO(2) nor does it lead to increased CO(2) retention; rather, it may even bring about a decrease in this trait. This finding suggests that acquiring experience in oxygen diving with a closed-circuit apparatus at shallow depths does not place the diver at a greater risk of central nervous system oxygen toxicity due to CO(2) retention.

Adult↗
PubMed2005

Exercise-induced intrapulmonary shunting of venous gas emboli does not occur after open-sea diving.

Paradoxical arterializations of venous gas emboli can lead to neurological damage after diving with compressed air. Recently, significant exercise-induced intrapulmonary anatomical shunts have been reported in healthy humans that result in widening of alveolar-to-arterial oxygen gradient. The aim of this study was to examine whether intrapulmonary shunts can be found following strenuous exercise after diving and, if so, whether exercise should be avoided during that period. Eleven healthy, military male divers performed an open-sea dive to 30 m breathing air, remaining at pressure for 30 min. During the bottom phase of the dive, subjects performed mild exercise at approximately 30% of their maximal oxygen uptake. The ascent rate was 9 m/min. Each diver performed graded upright cycle ergometry up to 80% of the maximal oxygen uptake 40 min after the dive. Monitoring of venous gas emboli was performed in both the right and left heart with an ultrasonic scanner every 20 min for 60 min after reaching the surface pressure during supine rest and following two coughs. The diving profile used in this study produced significant amounts of venous bubbles. No evidence of intrapulmonary shunting was found in any subject during either supine resting posture or any exercise grade. Also, short strenuous exercise after the dive did not result in delayed-onset decompression sickness in any subject, but studies with a greater number of participants are needed to confirm whether divers should be allowed to exercise after diving.

Adaptation, Physiological↗
PubMed2000

Seasonal changes in buoyancy and diving behaviour of adult grey seals.

Phocid seals go through dramatic seasonal changes in body mass and composition as a result of the spatial and temporal separation of foraging, reproduction and moulting. These changes in body fat content and body mass result in seasonal changes in buoyancy, which in turn may influence diving behaviour. We examined the longitudinal changes in buoyancy and diving behaviour of 14 adult grey seals (Halichoerus grypus) during two periods that represent maximal contrast in body mass and composition. During both the post-moulting (PM) and pre-breeding (PB) periods, grey seals were negatively buoyant. However, buoyancy increased by 47.9 % between the PM and PB periods. Descent rate was significantly faster during the PM period (1.0+/-0.07 m s(-1)) than during the PB period (0.7+/-0.06 m s(-1)), suggesting that seals were aided by negative buoyancy during the downward portion of dives. Ascent rate was also significantly faster during the PM period (0.8+/-0.06 m s(-1)) than during the PB period (0.6+/-0.05 m s(-1)), contradicting the prediction that more buoyant animals should ascend faster. The effects of drag could not account for this discrepancy. Dive depth and surface interval between dives did not differ significantly between the two periods. Similarly, the distribution of dive shapes used by individuals did not differ between the two periods. However, dive duration was significantly longer during the PB period than during the PM period (5.5+/-0.25 min compared with 4.4+/-0.24 min, respectively) as was time spent at the bottom of the dive (3.1+/-0.22 min compared with 2.5+/-0.15 min, respectively).

Adipose Tissue↗
PubMed2000

Estimation of the rate of oxygen consumption of the common eider duck (Somateria mollissima), with some measurements of heart rate during voluntary dives.

The relationship between heart rate (f(H)) and rate of oxygen consumption (V(O2)) was established for a marine diving bird, the common eider duck (Somateria mollissima), during steady-state swimming and running exercise. Both variables increased exponentially with speed during swimming and in a linear fashion during running. Eleven linear regressions of V(O2) (ml kg(-1 )min(-1)) on f(H) (beats min(-1)) were obtained: five by swimming and six by running the birds. The common regression was described by V(O2)=10.1 + 0.15f(H) (r(2)=0.46, N=272, P<0.0001). The accuracy of this relationship for predicting mean V(O2) was determined for a group of six birds by recording f(H) continuously over a 2-day period and comparing estimated V(O2) obtained using the common regression with (i) V(O2) estimated using the doubly labelled water technique (DLW) and (ii) V(O2) measured using respirometry. A two-pool model produced the most accurate estimated V(O2) using DLW. Because of individual variability within mean values of V(O2) estimated using both techniques, there was no significant difference between mean V(O2) estimated using f(H) or DLW and measured V(O2) values (P>0.2), although individual errors were substantially less when f(H) was used rather than DLW to estimate V(O2). Both techniques are, however, only suitable for estimating mean V(O2) for a group of animals, not for individuals. Heart rate and behaviour were monitored during a bout of 63 voluntary dives by one female bird in an indoor tank 1.7 m deep. Tachycardia occurred both in anticipation of and following each dive. Heart rate decreased before submersion but was above resting values for the whole of the dive cycle. Mean f(H) at mean dive duration was significantly greater than f(H) while swimming at maximum sustainable surface speeds. Heart rate was used to estimate mean V(O2) during the dive cycle and to predict aerobic dive limit (ADL) for shallow dives.

Animals↗
PubMed2000

Respiration and heart rate at the surface between dives in northern elephant seals.

All underwater activities of diving mammals are constrained by the need for surface gas exchange. Our aim was to measure respiratory rate (fb) and heart rate (fh) at the surface between dives in free-ranging northern elephant seals Mirounga angustirostris. We recorded fb and fh acoustically in six translocated juveniles, 1.8-2. 4 years old, and three migrating adult males from the rookery at Año Nuevo, California, USA. To each seal, we attached a diving instrument to record the diving pattern, a satellite tag to track movements and location, a digital audio tape recorder or acoustic datalogger with an external hydrophone to record the sounds of respiration and fh at the surface, and a VHF transmitter to facilitate recovery. During surface intervals averaging 2.2+/-0.4 min, adult males breathed a mean of 32.7+/-5.4 times at a rate of 15. 3+/-1.8 breaths min(-)(1) (means +/- s.d., N=57). Mean fh at the surface was 84+/-3 beats min(-)(1). The fb of juveniles was 26 % faster than that of adult males, averaging 19.2+/-2.2 breaths min(-)(1) for a mean total of 41.2+/-5.0 breaths during surface intervals lasting 2.6+/-0.31 min. Mean fh at the surface was 106+/-3 beats min(-)(1). fb and fh did not change significantly over the course of surface intervals. Surface fb and fh were not clearly associated with levels of exertion, such as rapid horizontal transit or apparent foraging, or with measures of immediately previous or subsequent diving performance, such as diving duration, diving depth or swimming speed. Together, surface respiration rate and the duration of the preceding dive were significant predictors of surface interval duration. This implies that elephant seals minimize surface time spent loading oxygen depending on rates of oxygen uptake and previous depletion of stores.

Animals↗
PubMed1994

When alcohol and water don't mix: diving under the influence.

The impairing effects of alcohol on divers' abilities to perform shallow-water entry dives were investigated under controlled conditions. Each of 13 male recreational divers, 21 to 35 years old, performed three shallow-entry dives during each of seven diving sessions at various blood alcohol concentrations (BACs). The mean group BACs of Diving Sessions 1-7 were 0, 17, 40, 71, 100, 123 and 97 mg/dl, respectively. Diving performances were videotaped and rated on their relative risk of injury due to contact with the pool bottom if the depth had actually been 3.5 feet. The data indicate progressive and significant impairment of diving performance at BACs of 40 mg/dl (or 0.04 g/dl, or 0.04%) and higher. Corroborating evidence of alcohol impairment was obtained from administering Field Sobriety Tests following Sessions 1, 5, 6 and 7; almost all subjects failed the tests at the higher BAC sessions. An analysis of the self-ratings of diving performances indicated that the divers were not aware of either their degraded performance or the increased risk of injury resulting from diving after drinking.

Adult↗
PubMed1987

[Evaluation of diving stress implication of analysis of work loads].

An investigation was conducted on the actual diving conditions of 2,996 divers in Japan except those engaged in fishery. Results of analysis made on the diving profiles and actual working conditions showed that some of their jobs required heavy load and that the burden was excessively large. Little study has been made for the proper evaluation of diving stress or work loads, but it has been assumed from these limited studies that the load is not so heavy. The load has been generally estimated to be about 1.8l/min STPD of oxygen consumption (VO2) during 40 l/min STPD of expiratory gas volume/min (VE). In our examination of their actual diving work, their work load was far greater than our expectation. It was in practice not only difficult to obtain the actual VO2 but also very difficult to determine their actual fatigue. Instead of these, it is necessary to establish an adequate index for evaluating diving work load. Studies have been made in our laboratory since 1981 and regression equations have been finally obtained, by which load during diving work can be determined using heart rate as index. Seven healthy males were chosen as subjects of the present study having a mean age of 34.4 yr and a mean diving history of 7.3 yr. First, performance time was acquired in each subject by bicycle ergometer exercise and the maximalen oxygen consumption (VO2-max) was obtained. In the second step, VO2-max was obtained by using the regulator apparatus for breathing during SCUBA diving. This value was 86.1% of the first step. The third step was made in a swimming pool.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Applied physiology of diving.

Recreational diving is a popular sport, although human ability to stay in and under water is severely limited physiologically. An understanding of these limitations enhances safety and enjoyment of sports diving. Breath-hold diving involves head-out water immersion, apnoea and submersion, exercise, cold stress, and pressure exposure. Each of these components, by itself, elicits prominent and specific physiological effects. Combination of these factors produces a unique and interesting physiological response generally known as diving reflex. Humans display weak diving responses, but exhibit no oxygen conservation function. Nevertheless, application of diving-induced physiological changes is now finding its way into clinical practice. Apnoea, face immersion, and head-out water immersion all show promise of clinical application. There are several spin-offs from diving research worth noting. Diuresis, enhancement of cardiac performance, and redistribution of blood flow, all produced by head-out water immersion, have been shown to be clinically useful, besides providing physiological data useful to space travel. Results from investigations on apnoea have been shown to be relevant to the following: treating some forms of cardiac arrhythmias; understanding drowning, sudden infant death syndrome and sleep apnoea; and confirming hyperventilation as the major cause of drowning. In comparison to marine mammals, humans are poor divers because of severe physiological constraints which limit their breath-hold time, diving depth, and ability to conserve body heat. Although under special circumstances humans can achieve unusually long breath-hold time and reach exceptional depth with a single breath, the sustainable working time and depth are only about 1 minute and 5 metres, respectively. Hypothermia inevitably results in divers working in the ocean. Without thermal protection, the intolerable limit of 35 degrees C is reached within 30 minutes in winter (10 degrees C) water and within 60 to 90 minutes in summer. Nevertheless, effective harvest work can be performed by humans in the ocean, and recreational benefits enhanced when these physiological limitations are respected. An unusual circulatory state exists during head-out water immersion in that there is a sustained increase of stroke volume. This results in 30% increase in cardiac output when the subject is resting in thermal neutral water, indicating a substantial overperfusion for the oxygen requirement. Furthermore, animal experiments showed that the elevated blood flow is preferentially channeled to the liver, fat, and the organs in the splanchnic region.(ABSTRACT TRUNCATED AT 400 WORDS)

Arrhythmias, Cardiac↗
PubMedDate not supplied

Scuba diving medical examinations in practice: a postal survey.

OBJECTIVE: To assess variability of opinion regarding fitness to dive among doctors currently doing diving medical examinations. DESIGN: Anonymous, reply-paid postal survey containing 15 clinical scenarios for which respondents were asked to declare the prospective scuba diver fit, unfit, fit after investigation or to offer specialist referral. PARTICIPANTS: All 81 doctors in Queensland, identified as members of the South Pacific Underwater Medical Society, who had completed approved training in underwater medicine, and who were doing diving medical examinations in June 1998. MAIN OUTCOME MEASURES: Variability in responses, and agreement with our interpretation of the action recommended by Australian Standard (AS) 4005.1-1992, the medical standard for fitness to scuba dive for recreational divers. RESULTS: 52 of the 81 questionnaires were returned (64% response rate). There was a wide variety of opinion about fitness to dive for all 15 hypothetical cases, with 70% consensus about unfitness in only four cases (one of which should have been referred according to AS guidelines) and fitness in only two cases (both of which should have been referred according to AS guidelines). No case was considered either fit or unfit by all respondents. Only 17.6% of responses recommended specialist referral, although the AS guidelines suggest that 10 of the 15 cases should be referred. One doctor failed 13 of the 15 potential divers outright and another passed seven outright and failed only four. For each case that the AS guidelines firmly indicate as unfit to dive, at least one respondent passed the hypothetical prospective diver as fit. CONCLUSIONS: There is no consensus among doctors who perform diving medical examinations as to what constitutes fitness to dive; current guidelines need to be improved.

Australia↗
PubMed2000

Exposure to soda-lime dust in closed and semi-closed diving apparatus.

BACKGROUND: Chronic exposure to hyperbaric hyperoxia and venous gas microembolism have been shown to contribute to the long term health effects of diving, especially diver's lung function. Factors related to special diving equipment may add to these effects. This study was conducted to evaluate possible additional hazards for respiratory function of divers employing closed and semi-closed diving apparatus. METHODS: We analyzed soda-lime dust found in the air-intake loop of a closed-circuit oxygen rebreathing diving apparatus which had passed through the filter screen of the diving apparatus's soda-lime cartridge. The geometrical characteristics were evaluated by scanning electron microscopy. The amount of dust that passed through the screen during a normal dive profile was measured by an artificial airflow through a filter membrane. After dives by subjects using these devices, the pH-value of water condensate in the air-intake hose was measured. RESULTS: There was a relevant amount of residual soda-lime dust found in the air-intake loop. The dust particles showed diameters down to 1 micron and a rounded structure. The total amount of dust averaged 9.6 mg.m-3 of breathing mixture. During diving, the mean pH-value of condensate in the hose is estimated at 8.87 (+/- 0.12). CONCLUSION: There is a relevant exposure to soda-lime dust in divers using closed-circuit rebreathing apparatus. This occupational exposure may contribute to chronic airway inflammation and subsequent development of small airway disease in divers.

Calcium Compounds↗
PubMed2001

Exposure to hyperoxia in diving and hyperbaric medicine--effects on blood cell counts and serum ferritin.

A reduction in hemoglobin concentration has been consistently reported after deep saturation dives, whereas reductions in thrombocyte counts and changes in biochemical parameters specific for liver function have been reported after some dives. In this study the contribution of exposure to hyperoxia to these changes were studied. Hemoglobin concentration, blood cell counts, serum ferritin, and biochemical parameters specific for liver damage were measured before and after a shallow 28-day saturation dive to a pressure of 250 kPa with the same hyperoxic exposure (40-50 kPa) as in a deep saturation dive in eight male divers. The same parameters were measured before, during, and after a standard 21-day hyperbaric oxygen (HBO2) treatment series in a selected group of 16 patients (8 male). There were significant reductions in hemoglobin concentrations of 3.8 +/- 4.7% (P = 0.023) and 10.2 +/- 5.3% (P = 0.003) after the HBO2 treatment series and dive, respectively, accompanied with reductions in red cell counts, reticulocyte counts, and hematocrit. There was an increase in ferritin concentrations of 29 +/- 21% (P = 0.002) and 107 +/- 43% (P < 0.001). In contrast to some deep dives, there were no changes in thrombocyte counts or biochemical parameters specific for liver damage. Exposure to hyperoxia contributes significantly to reduced hemoglobin and increased ferritin concentrations after saturation dives. The changes may reflect a shift of iron from synthesis of hemoglobin in the bone marrow to storage in macrophages caused by a downregulation of hemoglobin synthesis, or an increased oxidative stress. The changes are too small to be of clinical significance with respect to diving and HBO2 treatment.

Adult↗
PubMed2005

N-terminal pro brain natriuretic peptide increases after 1-h scuba dives at 10 m depth.

OBJECTIVES: The N-terminal pro brain natriuretic peptide (N-BNP) is a promising cardiac natriuretic peptide used as a clinical hormonal marker in cardiac dysfunction. The main stimulus for N-BNP synthesis and secretion is cardiac wall stress, which is recognized as a common denominator of many cardiac diseases. Diving is associated with environmental factors leading to variations in thoracic blood volume and hemodynamic changes. The purpose of the present study was to examine the changes in the concentration of N-BNP in healthy men during and after scuba diving. METHOD: There were 10 healthy military divers (mean age 33 yr) who performed a dive in the sea for 1 h at 10 m depth. Venous blood samples were taken at timed intervals to allow evaluation of plasma levels of N-BNP at different steps, namely at To (before immersion), at T30 min (during the dive, after a short surfacing), at T60 min (right after surfacing), at T300 min (post-dive), and finally at T24 h. Peptide blood concentrations were determined by electrochemoluminiscence immunoassay. Data were analyzed using parametric statistics. RESULTS: When compared with To, the results show a significant increase of N-BNP levels (in % of baseline levels) at T60(128 +/- 5%, p < 0.043) and at T300 (149 +/- 8%, p < 0.001). CONCLUSION: This preliminary study reveals that N-BNP rises with scuba diving. Our findings suggest that diving involves a mechanical strain on the heart with a persistent endocrine myocardial activity post-dive.

Adult↗
PubMedDate not supplied

Clinical observation: Beau's lines on fingernails after deep saturation dives.

Transverse furrows, or Beau's lines, were noted in the fingernails of all 6 divers following a deep saturation dive to apressure equal to 1100 feet (335 meters) ofsea water (3,370 kPa), and in 2 of6 divers following a similar dive to 1000 feet (305 meters) of sea water (3,164 kPa). Both dives took place at the Ocean Simulation Facility of the Navy Experimental Diving Unit in Panama City, Florida. The divers breathed a partial pressure of 0.40 - 0.44 atm abs (40.5 - 44.6 kPa) oxygen, with the balance helium, during most of the time under pressure. All divers performed hard work on bicycle ergometers during the dives. Four of the divers on the first dive were treated during the dive for pain-only decompression sickness. Beau's lines have been reported in numerous medical conditions such as typhus, rheumatic fever, malaria, myocardial infarction, and other severe metabolic stresses. To the author's knowledge this is the first report of Beau's lines associated with saturation diving.

Decompression↗