Symptoms and contributing factors of immersion pulmonary oedema (IPO) are not observed during non-immersed heart and lung function assessments. We report a case in which intense snorkelling led to IPO, which was subsequently investigated by duplicating cardiopulmonary exercise testing with (neoprene vest test - NVT) and without (standard test - ST) the wearing of a neoprene vest. The two trials utilised the same incremental cycling exercise protocol. The vest hastened the occurrence and intensity of dyspnoea and leg fatigue (Borg scales) and led to an earlier interruption of effort. Minute ventilation and breathing frequency rose faster in the NVT, while systolic blood pressure and pulse pressure were lower than in the ST. These observations suggest that restrictive loading of inspiratory work caused a faster rise of intensity and unpleasant sensations while possibly promoting pulmonary congestion, heart filling impairment and lowering blood flow to the exercising muscles. The subject reported sensations close to those of the immersed event in the NVT. These observations may indicate that increased external inspiratory loading imposed by a tight vest during immersion could contribute to pathophysiological events.

Head-out water immersion alters respiratory compliance which underpins defining pressure at a “Lung centroid” and the breathing “Static Lung Load”. In diving medicine as in designing dive-breathing devices a single value of lung centroid pressure is presumed as everyone’s standard. On the contrary, we considered that immersed respiratory compliance is disparate among a homogenous adult group (young, healthy, sporty). We wanted to substantiate this ample scattering for two reasons: (i) it may question the European standard used in designing dive-breathing devices; (ii) it may contribute to understand the diverse individual figures of immersed work of breathing. Resting spirometric measurements of lung volumes and the pressure–volume curve of the respiratory system were assessed for 18 subjects in two body positions (upright Up, and supine Sup). Measurements were taken in air (Air) and with subjects immersed up to the sternal notch (Imm). Compliance of the respiratory system ( Crs ) was calculated from pressure–volume curves for each condition. A median 60.45% reduction in Crs was recorded between Up-Air and Up-Imm (1.68 vs 0.66 L/kPa), with individual reductions ranging from 16.8 to 82.7%. We hypothesize that the previously disregarded scattering of immersion-reduced respiratory compliance might participate to substantial differences in immersed work of breathing.

AimsPathophysiology of reflex syncope is not fully understood but a vagal overactivity might be involved in this syncope. Previously, overexpression of muscarinic M2 receptors and acetylcholinesterase was found in particular in the heart and in lymphocytes of rabbits with vagal overactivity as well as in hearts of Sudden Infant Death Syndromes. The aim of this present study was to look at M2 receptor expression in blood of patients with reflex syncope. The second objective was to measure acetylcholinesterase expression in these patients.Methods and results136 subjects were enrolled. This monocenter study pooled 45 adults exhibiting recurrent reflex syncope compared with 32 healthy adult volunteers (18-50 years) and 38 children exhibiting reflex syncope requiring hospitalization compared with 21 controls (1-17 years). One blood sample was taken from each subject and blood mRNA expression of M2 receptors was assessed by qRT-PCR. Taking into account the non-symmetric distributions of values in both groups, statistical interferences were assessed using bayesian techniques. A M2 receptor overexpression was observed in adult and pediatric patients compared to controls. The medians [q1;q3] were 0.9 [0.3;1.9] in patients versus 0.2 [0.1;1.0] in controls; the probability that M2 receptor expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.99. Acetylcholinesterase expression was also increased 0.7 [0.4;1.6] in patients versus 0.4 [0.2;1.1] in controls; the probability that acetylcholinesterase expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.97. Both in adults and children, the expression ratio of M2 receptors over acetylcholinesterase was greater in the patient group compared with the control group.ConclusionM2 receptor overexpression has been detected in the blood of both, adults and children, exhibiting reflex syncope. As in our experimental model, i.e. rabbits with vagal overactivity, acetylcholinesterase overexpression was associated with M2 receptor overexpression. For the first time, biological abnormalities are identified in vagal syncope in which only clinical signs are, so far, taken into account for differential diagnosis and therapeutic management. Further work will be needed to validate potential biomarkers of risk or severity associated with the cholinergic system.

Background: Immersion pulmonary edema is potentially a catastrophic condition; however, the pathophysiological mechanisms are ill-defined. This study assessed the individual and combined effects of exertion and negative pressure breathing on the cardiovascular system during the development of pulmonary edema in SCUBA divers. Methods: Sixteen male professional SCUBA divers performed four SCUBA dives in a freshwater pool at 1 m depth while breathing air at either a positive or negative pressure both at rest or with exercise. Echocardiography and lung ultrasound were used to assess the cardiovascular changes and lung comet score (a measure of interstitial pulmonary edema). Results: The ultrasound lung comet score was 0 following both the dives at rest regardless of breathing pressure. following exercise, the mean comet score rose to 4.2 with positive pressure breathing and increased to 15.1 with negative pressure breathing. The development of interstitial pulmonary edema was significantly related to inferior vena cava diameter, right atrial area, tricuspid annular plane systolic excursion, right ventricular fractional area change, and pulmonary artery pressure. Exercise combined with negative pressure breathing induced the greatest changes in these cardiovascular indices and lung comet score. Conclusions: A diver using negative pressure breathing while exercising is at greatest risk of developing interstitial pulmonary edema. The development of immersion pulmonary edema is closely related to hemodynamic changes in the right but not the left ventricle. Our findings have important implications for divers and understanding the mechanisms of pulmonary edema in other clinical settings.

We aimed to analyse the relationship between training load/intensity and different heart rate variability (HRV) fatigue patterns in 57 elite Nordic-skiers. 1063 HRV tests were performed during 5 years. R-R intervals were recorded in resting supine (SU) and standing (ST) positions. Heart rate, low (LF), high (HF) frequency powers of HRV were determined. Training volume, training load (TL, a.u.) according to ventilatory threshold 1 (VT1) and VT2 were measured in zones I≤VT1; VT1VT2, IV for strength. TL was performed at 81.6±3.5% in zone I, 0.9±0.9% in zone II, 5.0±3.6% in zone III, 11.6±6.3% in zone IV. 172 HRV tests matched a fatigue state and four HRV fatigue patterns (F) were statistically characterized as F(HF-LF-)SU_ST for 121 tests, F(LF+SULF-ST) for 18 tests, F(HF-SUHF+ST) for 26 tests and F(HF+SU) for 7 tests. The occurrence of fatigue states increased substantially with the part of altitude training time (r2=0.52, p<0.001). This study evidenced that there is no causal relationship between training load/intensity and HRV fatigue patterns. Four fatigue-shifted HRV patterns were sorted. Altitude training periods appeared critical as they are likely to increase the overreaching risks.

In healthy divers, the occurrence of immersion pulmonary oedema (IPE) is commonly caused by contributory factors including strenuous exercise, cold water and negative-pressure breathing. Contrary to this established paradigm, this case reports on a 26-year-old, well-trained combat swimmer who succumbed to acute IPE during static immersion in temperate (21°C) water, while using a front-mounted counterlung rebreather. The incident occurred during repeated depth-controlled ascent practice at the French military diving school. It was discovered that the diver had attempted to stop any gas leakage into the system by over-tightening the automatic diluent valve (ADV) (25th notch of 27) during the dive, thus causing a high resistance to inspiratory flow. The ventilatory constraints imposed by this ADV setting were assessed as a 3.2 Joules·L⁻¹ inspiratory work of breathing and -5 kPa (-50 mbar) transpulmonary pressure. This report confirms the key role of negative pressure breathing in the development of interstitial pulmonary oedema. Such a breathing pattern can cause a lowering of thoracic, airway and interstitial lung pressure, leading to high capillary pressure during each inspiration. Repetition of the diving drills resulted in an accumulation of interstitial lung water extravasation, causing pathological decompensation and proven symptoms.

Introduction: Training loads and heart rate variability (HRV) were monitored over 69 weeks in a swimming Olympic champion to assess if different types of HRV changes occurred during fatigue episodes. Methods: Weekly training volume (km) and training load (TL, a.u.) were calculated. Morning HRV tests were performed by recording R-R intervals at rest during 8 min supine (SU) and 7 min standing (ST). HRV variables analysed were: heart rate (HR), power (in ms2) of low (LF), high (HF) and (LF+HF) frequencies. Results: Over the period considered, training volume and TL amounted to 2408 km and 1075 a.u.. 55 HRV tests were completed, 10 took place in conditions of ‘fatigue’ defined by the coach after training sessions.Three different sub-categories of fatigue were disclosed: type 1. F(HF-LF-)SU_ST (n=6) embeded a decrease inHF (-55%), LF( -23%) and an increase in HR (+21%) in SU, concomitant with a decrease in HF (-50%), LF(-50%) and an increase in HR (+16%) in ST; type 2. F(LFST) (n=2) featured a decrease in LF (-61%) and an increase in HR (+19%) in ST; type 3. F(HFSUHF+ST) embedded a decrease in HF (-72%) and an increase inHR (+10%) in SU, with an increase in HF (+65%) and a decrease in HR (-14%) in ST. Conclusion: In an elite swimmer, three different types of ‘fatigue’ shifts in HRV patterns were sorted. Each type corresponded to specific changes in sympathovagal settings. To our knowledge, this study is the first one reporting a practical way of monitoring different types of fatigue apart from Nordic skiers.; ;

Among the tools proposed to assess the athlete's "fatigue," the analysis of heart rate variability (HRV) provides an indirect evaluation of the settings of autonomic control of heart activity. HRV analysis is performed through assessment of time-domain indices, the square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals (RMSSD) measured during short (5 min) recordings in supine position upon awakening in the morning and particularly the logarithm of RMSSD (LnRMSSD) has been proposed as the most useful resting HRV indicator. However, if RMSSD can help the practitioner to identify a global "fatigue" level, it does not allow discriminating different types of fatigue. Recent results using spectral HRV analysis highlighted firstly that HRV profiles assessed in supine and standing positions are independent and complementary; and secondly that using these postural profiles allows the clustering of distinct sub-categories of "fatigue." Since, cardiovascular control settings are different in standing and lying posture, using the HRV figures of both postures to cluster fatigue state embeds information on the dynamics of control responses. Such, HRV spectral analysis appears more sensitive and enlightening than time-domain HRV indices. The wealthier information provided by this spectral analysis should improve the monitoring of the adaptive training-recovery process in athletes.

Small bowel damage is frequent but underdiagnosed among critically ill patients with shock. High catecholamine doses may have a deleterious effect on mesenteric blood flow. Plasma intestinal fatty acid-binding protein (I-FABP) concentration is a marker of enterocyte damage, whereas plasma citrulline concentration is a marker of functional enterocyte mass. We hypothesized that high doses of catecholamines in critically ill patients may be associated with enterocyte damage. This study aimed to determine the link between catecholamine use and dose with enterocyte damage. This is a prospective observational study performed in a large regional university teaching hospital. Critically ill patients requiring epinephrine and/or norepinephrine at admission to a medical intensive care unit (ICU) were included, as well as controls not receiving catecholamines. We evaluated at admission plasma I-FABP and citrulline concentrations, abdominal perfusion pressure (APP), and variables relating to prognosis and treatment. Patients were categorized according to the quartiles of catecholamine dose at ICU admission. Sixty critically ill patients receiving catecholamines and 27 not receiving catecholamines were included. Plasma I-FABP was higher among patients receiving catecholamine than in controls. Among patients receiving catecholamines, a dose of 0.48 γ kg min or more at ICU admission was associated with a higher I-FABP concentration. A Sepsis-related Organ Failure Assessment score higher than 11 and plasma I-FABP more than 524 pg mL at ICU admission were independently associated with 28-day mortality (odds ratio, 4.0 [1.24-12.95] and odds ratio, 4.90 [1.44-16.6], respectively). Catecholamine use is associated with I-FABP elevation in critically ill patients. Critically ill patients receiving more than 0.48 γ kg min of epinephrine and/or norepinephrine at ICU admission have high I-FABP concentrations. This suggests that enterocyte damage reflects the severity of shock, and an adverse effect of catecholamines per se is possible.

Immersion in thermoneutral water increases cardiac output and peripheral blood flow and reduces systemic vascular resistance. This study examined the effects of head-out water immersion on vascular function. Twelve healthy middle-aged males were immersed during 60 min in the seated position, with water at the level of xiphoid. Local and central vascular tone regulating systems were studied during that time. Brachial artery diameter and blood flow were recorded using ultrasonography and Doppler. Endothelial function was assessed with flow-mediated dilation. Results were compared with the same investigations performed under reference conditions in ambient air. During water immersion, brachial artery diameter increased (3.7 ± 0.2 mm in ambient air vs. 4 ± 0.2 mm in water immersion; p < 0.05). Endothelium-mediated dilation was significantly lower in water immersion than in ambient air (10% vs. 15%; p = 0.01). Nevertheless, the difference disappeared when the percentage vasodilatation of the brachial artery was normalized to the shear stimulus. Smooth muscle-mediated dilation was similar in the 2 conditions. Spectral analysis of systolic blood pressure variability indicated a decrease in sympathetic vascular activity. Plasma levels of nitric oxide metabolites remained unchanged, whereas levels of natriuretic peptides were significantly elevated. An increase in brachial blood flow, a decrease in sympathetic activity, a warming of the skin, and an increase in natriuretic peptides might be involved in the increase in reference diameter observed during water immersion. Endothelial cell reactivity and smooth muscle function did not appear to be altered.

BACKGROUND Human thermal responses during prolonged whole-body immersion in cold water are of interest for the military, especially French SEALS. This study aims at describing the thermo-physiological responses. METHODS There were 10 male military divers who were randomly assigned to a full immersion in neutral (34 degrees C), moderately cold (18 degrees C), and cold (10 degrees C) water wearing their operational protective devices (5.5 mm wetsuit with 3.0 mm thick underwear) for 6 h in a static position. Rectal temperature (T(re)) and 14 skin temperatures (T(sk)), blood analysis (stress biomarkers, metabolic substrates), and oxygen consumption (Vo2) were collected. RESULTS At 34 degrees C, there were no significant modifications of the thermo-physiological responses over time. The most interesting result was that rates of rectal temperature decrease (0.15 +/- 0.02 degrees C x min(-1)) were the same between the two cold stress experimental conditions (at 18 degrees C and 10 degrees C). At the final experiment, rectal temperature was not significantly different between the two cold stress experimental conditions. Mean T(sk) decreased significantly during the first 3 h of immersion and then stabilized at a lower level at 10 degrees C (25.6 +/- 0.8 degrees C) than at 18 degrees C (29.3 +/- 0.9 degrees C). Other results demonstrate that the well-trained subjects developed effective physiological reactions. However, these reactions are consistently too low to counterbalance the heat losses induced by cold temperature conditions and long-duration immersion. CONCLUSION This study shows that providing divers with thermal protection is efficient for a long-duration immersion from a medical point of view, but not from an operational one when skin extremities were taken into account.

Aim: This study assessed hemodynamic changes and myocardial function after prolonged dynamic cold water immersions with hyperbaric hyperoxic exposure. Methods: Trained military divers were studied during 8-hour (6 subjects) and 12-hour (6 subjects) dives in a hyperbaric chamber (1.7 and 3 bar) in 18°C water. Subjects were breathing hyperoxic gas (100% oxygen or up to 1.7 bar PO2) and performed bouts of physical exercise. Conventional and speckle tracking transthoracic echocardiography (TTE) were performed before, immediately after, and 15 hours after dives. Results: We observed a decrease in left and right ventricular preloads, and lowered stroke volume immediately after dives. These parameters remained below baseline values 15h after dive termination. These changes were not significantly different between 8h and 12h dives. Speckle tracking analysis showed altered function of the left and right ventricles reflected by a transient decrease in ventricular parameters as measured by echography in the hour immediately after the end of immersion (table). Conclusion: Hemodynamic changes and transient alterations in strain and strain rate myocardial parameters were assessed immediately after 8 to 12 h dives. Immersion-linked changes in blood volume were likely involved in lowering cardiac preload and stroke volume. Altered ventricular strain and strain rates could be the result of lowered blood volume, hyperoxic breathing and increased cardiac pre- and after-load.

Este artículo de investigación tiene como objetivo realizar la medición de las variaciones de eficiencia de los países productores de biocombustibles en Latinoamérica. Se utilizó la metodología no paramétrica de análisis envolvente de datos (DEA), que permitió calcular la frontera de eficiencia de Brasil, Colombia, Argentina, Ecuador, México, Paraguay, Perú, Bolivia y Uruguay. La información analizada se obtuvo de la base de datos FAOSTAT año 2010. Los resultados mostraron el liderazgo de Perú y Brasil, con eficiencias igual a 1 en la producción de biodiésel y bioetanol. De los 9 países analizados, 7 presentaron bajos niveles de eficiencia en la producción de biocombustibles y solo uno (Paraguay) mostró tener eficiencia media en la fabricación de bioetanol.This research article has as objective to carry out the measurement of changes in efficiency of the countries biofuel producers in Latin America. The methodology was used non-parametric data envelopment analysis (DEA), allowing to compute the efficient frontier of the countries Brazil, Colombia, Argentina, Ecuador, Mexico, Paraguay, Peru, Bolivia and Uruguay. The analyzed information was obtained from FAOSTAT database of 2010. The results showed the leadership of Peru and Brazil with efficiencies equal to 1 in the production of biodiesel and bioethanol. Of the 9 countries analyzed, 7 had low levels of efficiency in the production of biofuels and only one (Paraguay), showed average efficiency in the manufacture of bioethanol.Este artigo de investigação tem por objectivo realizar a medição das variações de eficiência dos países produtores de biocombustíveis na América Latina. Utilizou-se a metodologia na paramétrica de análise envolvente de dados (DEA) que permitiu calcular a fronteira de eficiência dos países Brasil, Colômbia, Argentina, Equador, México, Paraguai, Peru, Bolívia e Uruguai. A informação analisada foi obtida pela base de dados FAOSTAT ano 2010. Os resultados mostraram a liderança do Peru e Brasil com eficiências igual a 1 na produção de biodiesel e bioetanol. Dos 9 países analisados, 7 apresentaram baixos níveis de eficiência na produção de biocombustíveis e só uma (Paraguai) mostrou ter eficiência média na fabricação de bioetanol.

Let R be an associative ring. An additive mapping d:R→R is called a Jordan derivation if d(x2)=d(x)x+xd(x) holds for all x∈R. The objective of the present paper is to characterize a prime ring R which admits Jordan derivations d and g such that [d(xm),g(yn)]=0 for all x,y∈R or d(xm)∘g(yn)=0 for all x,y∈R, where m⩾1 and n⩾1 are some fixed integers. This partially extended Herstein’s result in [6, Theorem 2], to the case of (semi)prime ring involving pair of Jordan derivations. Finally, we apply these purely algebraic results to obtain a range inclusion result of continuous linear Jordan derivations on Banach algebras.

Aim. - To assess the effects of water immersion on cardiovascular requirements, 30 min immersed versus air steady exercises at neutral temperature were compared in two settings:similar energy expenditure (60% maximal oxygen consumption; series 1) and similar ergometric workload (120W; series 2). For 15 healthy male subjects, the arterial blood pressure, heart rate, thoracic fluid conductivity (TFC), cardiac index (CI) and stroke index (SI) were monitored at rest, during the exercise period and during 30 min of post-exercise recovery in two conditions. Plasma atrial natriuretic peptide (ANP) was also measured. Results. - Resting water immersion increased TFC, CI, SI, and systolic arterial pressure (SAP). During exercise the average CI, SI and SAP were not different in water and air in series 1, but in series 2 CI, SI, heart rate, systolic and diastolic arterial pressures were higher in water. Plasma ANP was higher after immersed exercises. During recovery, CI was similar after either exercise, while SI was lower and heart rate higher following immersion, consistent with a lower effective circulatory volume than after exercise in air. TFC was high, as reflecting an increased interstitial fluid content in the lung. Conclusions. - Cardiovascular requirements for exercising in water were markedly higher than in air and straining of lung parenchyma. (C) 2011 Elsevier Masson SAS. All rights reserved.

Many researchers have investigated the effectiveness of contrast water therapy (CWT) or compression stockings (CS) during recovery, using subsequent performance as the principal outcome measure. However, data in the literature are contradictory, mainly because of the methodology used. Purpose: Based on well-controlled performance measures, this study aimed to compare the effects of CWT, CS or passive recovery (PR) on subsequent performance. Methods: After inclusion based on reproducibility criteria (intra-participant variability in performance test lower than the expected differences between the recovery interventions, i.e. 1.5%), 12 competitive male cyclists (peak power output: 5.0 ± 0.2 W/kg; cycling practice: 4.9 ± 0.4 times/week; intra-participant variability: 1.2 ± 0.2%) came to the laboratory three times in a random crossover design. Each time visit, they performed a tiring exercise on a cycle ergometer, followed by a 5-min performance test during which the mean power output was recorded, separated by a 15-min recovery period during which a 12-min PR, CWT (1:2 (cold: 10-12°C to warm: 36-38°C) min ratio) or CS (~20 mmHg) was implemented. Results: Compared with PR (353.8 ± 13.1 W), performance was significantly higher after CWT (368.1 ± 12.3 W) and CS (360.5 ± 14.8 W). Moreover, performance was significantly higher after CWT than after CS. Conclusion: Athletes can use this information as a way of improving their performance in competition format using repeated high-intensity exercises in a short period of time, such as in mountain bike, track or BMX races. Moreover, these data reinforce interest for researchers to consider performance tests with high test-retest reproducibility, especially when small but real benefits are expected.

PurposeThis longitudinal study aimed at comparing heart rate variability (HRV) in elite athletes identified either in 'fatigue' or in 'no-fatigue' state in 'real life' conditions.Methods57 elite Nordic-skiers were surveyed over 4 years. R-R intervals were recorded supine (SU) and standing (ST). A fatigue state was quoted with a validated questionnaire. A multilevel linear regression model was used to analyze relationships between heart rate (HR) and HRV descriptors [total spectral power (TP), power in low (LF) and high frequency (HF) ranges expressed in ms(2) and normalized units (nu)] and the status without and with fatigue. The variables not distributed normally were transformed by taking their common logarithm (log10).Results172 trials were identified as in a 'fatigue' and 891 as in 'no-fatigue' state. All supine HR and HRV parameters (Beta±SE) were significantly different (P<0.0001) between 'fatigue' and 'no-fatigue': HRSU (+6.27±0.61 bpm), logTPSU (-0.36±0.04), logLFSU (-0.27±0.04), logHFSU (-0.46±0.05), logLF/HFSU (+0.19±0.03), HFSU(nu) (-9.55±1.33). Differences were also significant (P<0.0001) in standing: HRST (+8.83±0.89), logTPST (-0.28±0.03), logLFST (-0.29±0.03), logHFST (-0.32±0.04). Also, intra-individual variance of HRV parameters was larger (P<0.05) in the 'fatigue' state (logTPSU: 0.26 vs. 0.07, logLFSU: 0.28 vs. 0.11, logHFSU: 0.32 vs. 0.08, logTPST: 0.13 vs. 0.07, logLFST: 0.16 vs. 0.07, logHFST: 0.25 vs. 0.14).ConclusionHRV was significantly lower in 'fatigue' vs. 'no-fatigue' but accompanied with larger intra-individual variance of HRV parameters in 'fatigue'. The broader intra-individual variance of HRV parameters might encompass different changes from no-fatigue state, possibly reflecting different fatigue-induced alterations of HRV pattern.

Background: A dysregulation of the cardiac autonomic nervous system, studied by baroreflex sensitivity (BRS), has been shown in patients with COPD related to cigarette smoking. Several factors including hypoxemia, poor physical fitness and pulmonary hyperinflation have been suspected. Occupational COPD is frequent in dairy farmers, but patients9 characteristics might be different compared with smoking-related COPD. Objective: To examine the presence and eventually the causes of cardiac autonomic nervous dysregulation in dairy farmers with COPD. Methods: BRS was compared between 2 groups of patients with mild/moderate COPD (related either to cigarette smoking or to dairy farming) and 2 groups of healthy matched controls. Peak workload served to evaluate physical fitness. Pulmonary hyperinflation was judged by the ratio of inspiratory capacity (IC) on total lung capacity (TLC). PaO2 was measured at rest. Results: The main results are given in a Table. There was a positive correlation between PaO2 and BRS (r2=0.16; p Conclusions: Depressed baroreflex sensitivity, a characteristic of smoking-related COPD, was not found in dairy farmers with mild/moderate COPD. This difference could be due to a lower PaO2 in smoking-related COPD patients.