Relax from the holiday on the edge of the lagoon : turquoise waters and red legs !

We report a case of livedo reticularis of the lower limbs in a 30-year-old woman scuba diver after a diving session. Consideration of the differential diagnoses, the clinical picture, and the course of the symptoms led to a diagnosis of cutaneous decompression sickness. This accident, which resolved favorably in this scuba diver without any right-to-left shunt, is an alarm signal that calls for her to comply strictly with safety rules before resuming scuba diving, to avoid a more serious accident.

[Capillary leak syndrome secondary to decompression sickness: A case report]. / Syndrome de fuite capillaire secondaire à un accident de décompression : à propos d'un cas.

BACKGROUND: Capillary leak syndrome is a rare type of decompression sickness (DCS) that may be responsible for hypovolemic shock with edema. CLINICAL CASE: A 21-year-old amateur diver suffered from an inner ear DCS following air diving to 96msw. He presented subsequent deterioration with hypovolemia and facial edema secondary to capillary leak syndrome. DISCUSSION: In DCS, bubbles formation alters the wall of blood vessels and activates complex biochemical mechanisms inducing extravascular protein leakage. The clinical expression of this syndrome is variable, ranging from simple hemoconcentration to hypovolemic shock. Close clinical-biological monitoring of patients with elevated hematocrit with or without hypoalbuminemia is advisable. Early vascular filling with albumin infusion may prevent the occurrence of hypovolemic shock and improve the prognosis.

Alterations in Body Fluid Balance During Fin Swimming in 29 °C Water in a Population of Special Forces Divers.

Highly trained "combat swimmers" encounter physiological difficulties when performing missions in warm water. The aim of this study was to assess the respective roles of immersion and physical activity in perturbing fluid balance of military divers on duty in warm water. 12 trained divers performed 2 dives each (2 h, 3 m depth) in fresh water at 29 °C. Divers either remained Static or swam continuously (Fin) during the dive. In the Fin condition, oxygen consumption and heart rate were 2-fold greater than during the Static dive. Core and skin temperatures were also higher (Fin: 38.5±0.4 °C and 36.2±0.3 °C and Static: 37.2±0.3 °C and 34.3±0.3 °C; respectively p=0.0002 and p=0.0003). During the Fin dive, the average mass loss was 989 g (39% urine loss, 41% sweating and 20% insensible water loss and blood sampling); Static divers lost 720 g (84% urine loss, 2% sweating and 14% insensible water loss and blood sampling) (p=0.003). In the Fin condition, a greater decrease in total body mass and greater sweating occurred, without effects on circulating renin and aldosterone concentrations; diuresis was reduced, and plasma volume decreased more than in the Static condition.

Argon blocks the expression of locomotor sensitization to amphetamine through antagonism at the vesicular monoamine transporter-2 and mu-opioid receptor in the nucleus accumbens.

We investigated the effects of the noble gas argon on the expression of locomotor sensitization to amphetamine and amphetamine-induced changes in dopamine release and mu-opioid neurotransmission in the nucleus accumbens. We found (1) argon blocked the increase in carrier-mediated dopamine release induced by amphetamine in brain slices, but, in contrast, potentiated the decrease in KCl-evoked dopamine release induced by amphetamine, thereby suggesting that argon inhibited the vesicular monoamine transporter-2; (2) argon blocked the expression of locomotor and mu-opioid neurotransmission sensitization induced by repeated amphetamine administration in a short-term model of sensitization in rats; (3) argon decreased the maximal number of binding sites and increased the dissociation constant of mu-receptors in membrane preparations, thereby indicating that argon is a mu-receptor antagonist; (4) argon blocked the expression of locomotor sensitization and context-dependent locomotor activity induced by repeated administration of amphetamine in a long-term model of sensitization. Taken together, these data indicate that argon could be of potential interest for treating drug addiction and dependence.

Relation between cervical and thoracic spinal canal stenosis and the development of spinal cord decompression sickness in recreational scuba divers.

STUDY DESIGN: Retrospective case-control study. OBJECTIVES: The intent of this study was to investigate the relationships between vertebral degenerative changes resulting in spinal canal stenosis, spinal cord lesions and the development of spinal cord decompression sickness (DCS) in scuba divers. SETTING: Referral hyperbaric facility, Toulon, France. METHODS: We examined 33 injured divers less than 50 years old by cervical and thoracic MRI and compared them with 34 matched control divers. The number of intervertebral disk abnormalities and the degree of canal compression were analyzed on T2-weighted sagittal images using a validated grading system developed recently. The presence and the distribution of hyperintense cord lesions in relation with the accident and the recovery status at 6 months were also assessed. RESULTS: Canal spinal narrowing was more common in injured divers than in controls (79% vs. 50%, OR=3.7 [95% CI, 1.3-10.8], P=0.021). We found a significant linear association between the extent of canal stenosis, multisegmental findings and the development of spinal cord decompression sickness. MRI intramedullary lesions were significantly more frequent in divers with incomplete recovery (OR=16 [95% CI, 2.6-99], P=0.0014), but statistical analysis failed to demonstrate a significant relationship between canal compression, signal cord abnormalities and a negative clinical outcome. CONCLUSIONS: These results suggest that divers with cervical and thoracic spinal canal stenosis, mainly due to disk degeneration, are at increased risk for the occurrence of spinal cord decompression sickness.

The underestimated compression effect of neoprene wetsuit on divers hydromineral homeostasis.

This study aimed at demonstrating that the neoprene wetsuit provides not only thermal protection. Compression it exerts on the diver's shell significantly impacts hydromineral homeostasis by restraining the systemic vascular capacity and secondarily increasing urine output on dry land and during scuba diving. 8 healthy divers underwent five 2-h sessions: sitting out of water in trunks (control situation), sitting out of water wearing a wetsuit, and 3 wetsuit scuba-immersed sessions at 1, 6 and 12 msw depth, respectively. Urine volumes and blood samples were collected. Hemoglobin (Hb), hematocrit (Ht) and plasma sodium concentration were measured. Interface pressure between the garment and the skin was measured at 17 sites of the body shell, with a pressure transducer. Mean interface pressures between wetsuit and skin amounted to: 25.8±2.8 mm Hg. Whatever the depth, elastic recoil tension of wetsuit material was unchanged by immersion. Weight loss was respectively 2 and 3 times greater when wetsuit was worn out of water (430 g) and during immersion (710 g) than when divers did not wear any wetsuit out of water (235 g; p<0.05). Urine volume accounted for 85% of weight loss in either session. Weight loss and urine volume were similar whatever immersion depth. The decrease in plasma volume amounted to 8% of urine volume when divers did not wear any wetsuit out of water, and to 30% when wetsuit was worn out of water or during immersion. Diving wetsuit develops a pressure effect that alters diver's hydromineral homeostasis. During immersion, the wetsuit pressure merges into the larger main effect of hydrostatic pressure to reduce water content of body fluids, unrelated to immersion depth.

Risks factors for recurrent neurological decompression sickness in recreational divers: a case-control study.

AIM: Individual or environmental factors that predispose to the recurrence of neurological decompression sickness (DCS) in scuba divers are not known and preventive measures designed to mitigate the risk of a subsequent episode remain empirical. The aim of this controlled study was to examine some potential risk factors predictive of recurrent DCS event that may lead to practical recommendations for divers who wish to continue diving after an initial episode. METHODS: Age, gender, diving experience, presence of a large right-to-left shunt (RLS) and diving practice following post-DCS resumption were evaluated as potential predictors of a further DCS in recreational divers admitted in our hyperbaric facility over a period of 12 years. RESULTS: Twenty-four recurrent cases and 50 divers treated for a single DCS episode which continued diving were recruited after review of medical forms and follow-up interview by telephone. After controlling for potential confounding variables between groups, multivariate analysis revealed that experienced divers (OR, 3.8; 95%CI, 1.1-14; P=0.03), the presence of large RLS (OR, 5.4; 95%CI, 1.5-19.7; P=0.006) and the lack of changes in the way of diving after prior DCS (OR, 8.4; 95%CI, 2.3-31.1; P=0.001) were independently associated with a repeated episode. CONCLUSION: The findings highlight the importance for divers to adopt conservative dives profiles or to use preferentially oxygen-enriched breathing mixtures after an initial DCS. Closure of a documented RLS through a large patent foramen ovale as a secondary preventive procedure for individuals that cannot adapt their diving practice remains debatable.

[Acute coronary event revealed by diving-related pulmonary edema]. / Accident coronarien aigu révélé par un oedème pulmonaire survenu en plongée sous-marine.

We report the case of a 64-year-old healthy male diver who presented an unusual diving-related pulmonary edema induced by a painless myocardial infarction with normal coronary arteriography. We review the related literature and discuss the pathophysiologic mechanisms that would contribute to provoke this myocardial injury during diving.

Relation between right-to-left shunts and spinal cord decompression sickness in divers.

The role of right-to-left shunting (RLS) in spinal cord decompression sickness (DCS) remains uncertain and could differ according to the distribution of lesion in spinal cord with a higher risk of upper spinal cord involvement in divers presenting a large patent foramen ovale. The aims of this study were to assess the prevalence of RLS with transcranial doppler ultrasonography in 49 divers referred for spinal cord DCS and compare it with the prevalence of RLS in 49 diving controls, and to determine a potential relation between RLS and lesion site of spinal cord. The proportion of large RLS was greater in DCS divers than in healthy control divers (odds ratio, 3.6 [95 % CI, 1.3 to 9.5]; p = 0.017). Shunting was not associated with the increased incidence of cervical spinal cord DCS (OR, 1.1 [95 % CI, 0.3 to 3.9]; p = 0.9) while a significant relationship between large RLS and spinal cord DCS with thoracolumbar involvement was demonstrated (OR, 6.9 [95 % CI, 2.3 to 20.4]; p < 0.001). From the above results, we conclude that the risk of spinal cord DCS in divers with hemodynamically relevant RLS is higher than in divers without RLS, particularly in their lower localization.

Preventive effect of pre-dive hydration on bubble formation in divers.

OBJECTIVE: To investigate whether prehydration 90 min before a dive could decrease bubble formation, and to evaluate the consequent adjustments in plasma volume (PV), water balance and plasma surface tension (ST). METHODS: Eight military divers participated in a crossover trial of pre-dive hydration using saline-glucose beverage (protocol 1) and a control dive with no prehydration (protocol 2). Drink volume was 1300 ml (osmolality 324 mOsm/l) and drinking time was 50-60 min. The diving protocol consisted of an open sea field air dive at 30 msw depth for 30 min followed by a 9 min stop at 3 msw. Haemodynamic parameters, body weight measurements, urine volume and blood samples were taken before/after fluid intake and after the dive. Decompression bubbles were examined by a precordial pulsed Doppler. RESULTS: Bubble activity was significantly lower for protocol 1 than for protocol 2. PV increased after fluid ingestion by 3.5% and returned toward baseline after diving for protocol 1, whereas it decreased by 2.2% after diving for protocol 2. Differences in post-dive PV between the two conditions were highly significant. Body weight loss before/after diving and post-dive urine volume after diving were significant in both protocols, but the relative decline in weight remained lower for protocol 1 than for protocol 2, with reduction of negative water balance due to higher fluid retention. There were no differences in ST after fluid intake and after diving for the two protocols. CONCLUSION: Pre-dive oral hydration decreases circulatory bubbles, thus offering a relatively easy means of reducing decompression sickness risk. The prehydration condition allowed attenuation of dehydration and prevention of hypovolaemia induced by the diving session. Hydration and diving did not change plasma surface tension in this study.

Influence of repetitive open sea dives and physical exercises on right-to-left shunting in healthy divers.

OBJECTIVE: Paradoxical gas embolism through right-to-left (R/L) shunts is considered as a potential cause of certain types of decompression sickness. AIM: To assess whether 4 months of repetitive diving and strenuous exercises would lead to an increased prevalence of R/L shunting in a group of military divers. METHODS: Using a standardised contrast-enhanced transcranial Doppler technique, 17 divers were re-examined for the presence of a R/L shunt 4 months after their initial examinations. R/L shunts were classified as type I if observed only after a straining manoeuvre, and type II if present at rest. RESULTS: Initial prevalence of R/L shunt was 41%: six type I shunts and one type II. At the second examination, prevalence was 47%, with the appearance of one type I shunt that was not previously present. We found no significant increase in the prevalence and size of R/L shunts. CONCLUSION: It is speculated that diving-related phenomena, such as variations in right atrial pressures during the end stages of or events immediately after a dive could generate an R/L shunt. However, extreme conditions of repetitive diving and strenuous exercises do not cause permanent modification in R/L permeability over a period of 4 months.

[Decompression sickness accident management in remote areas. Use of immediate in-water recompression therapy. Review and elaboration of a new protocol targeted for a mission at Clipperton atoll]. / Gestion d'un accident de plongée en situation d'isolement. Intérêt de la recompression thérapeutique par immersion. Revue et proposition d'un nouveau protocole à l'occasion d'une mission sur l'atoll de Clipperton.

In-Water Recompression (IWR) is defined as a treatment of decompression sickness by immediate underwater recompression after the onset of symptoms in remote areas where hyperbaric chambers are not available. At least three methods of IWR have been published. They used pure oxygen breathing for prolonged periods of time at a depth of 9 m. IWR effectiveness in comparison with standard recompression techniques has not been assessed. IWR should be used in remote localities as an immediate measure to stop the evolution of decompression illness before evacuating the victim for subsequent treatment to the nearest hyperbaric facility. Resulting from environmental conditions, the risks of drowning and hypothermia are the most often quoted, pure oxygen breathing at 9 m can also expose to acute oxygen toxicity. The objectives of this work are: first, to examine existing published methods of IWR; second, to propose a new method of IWR. All published methods of IWR involve victim returning underwater for a long period of time. But dehydration due to a long period of immersion can worsen symptoms of decompression illness and acute oxygen toxicity is also related to the duration of the exposition. In response to these considerations we developed a shorter method of conducting IWR specifically targeted for a diving mission at Clipperton atoll in the Northern Pacific Ocean.