Exercise-associated hyponatremia: role of cytokines

Hyponatremia-A New Diagnostic Marker for Complicated Acute Appendicitis in Children: A Systematic Review and Meta-Analysis

Background: Acute appendicitis in the pediatric population remains a diagnostic challenge for clinicians. Despite many biochemical markers, imaging modalities and scoring systems, initial misdiagnosis and complication rates are high in children. This suggests the need for investigations directed towards new diagnostic tools to aid in the diagnosis. Recent studies have shown a correlation between serum sodium levels and complicated appendicitis. Although the exact reasons for hyponatremia in patients with complicated appendicitis are not known, there is persuasive data to support the role of pro-inflammatory cytokines such as IL-6 in the non-osmotic release of antidiuretic hormone. This meta-analysis aims to investigate all available data on hyponatremia as a diagnostic marker of complicated appendicitis in the pediatric population. Methods: The literature search was conducted by two independent investigators according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The scientific databases (PubMed, EMBASE, Web of Science, and Scopus) were systematically searched for relevant studies using the keywords (hyponatremia) AND (appendicitis) AND (children). The methodological quality was assessed using a validated scale, and RevMan 5.4 software was utilized for pooled analysis. Results: Seven studies were included in the final meta-analysis, five of which were retrospective. A total of 1615 and 2808 cases were distributed into two groups: group A with complicated appendicitis and group B with uncomplicated acute appendicitis, respectively. The studies compared serum sodium levels of patients among the groups. Pooling the data demonstrated significantly lower serum sodium levels in children with complicated appendicitis vs. the non-complicated appendicitis (WMD: −3.29, 95% CI = −4.52 to −2.07, p < 0.00001). The estimated heterogeneity among the included studies was substantial and statistically significant (I2 = 98%, p < 0.00001). Conclusion: The results of the present meta-analysis indicate that hyponatremia has potential to be utilized as a biochemical marker in the diagnosis of complicated appendicitis in the pediatric population. However, well designed prospective diagnostic efficiency studies are essential to consolidate the association between hyponatremia and complicated acute appendicitis.

Changes in Factors Regulating Serum Sodium Homeostasis During Two Ultra-Endurance Mountain Races of Different Distances: 69km vs. 121km

Overdrinking and non-osmotic arginine vasopressin release are the main risk factors for exercise-associated hyponatremia (EAH) in ultra-marathon events. However, particularly during ultra-marathon running in mountainous regions, eccentric exercise and hypoxia, which have been shown to modulate inflammation, hormones regulating fluid homeostasis (hypoxia), and oxidative stress, could contribute to serum sodium changes in a dose-dependent manner. To the best of our knowledge, the contribution of these factors, the extent of which depends on the duration and geographical location of the race, has not been well studied. Twelve male participants (11 finishers) of the short (69km, 4,260m elevation-gain) and 15 male participants (seven finishers) of the long (121km, 7,554m elevation-gain) single-stage Südtirol Ultra Sky-Race took part in this observational field study. Venous blood was drawn immediately before and after the race. Analyses included serum sodium concentration, copeptin (a stable marker for vasopressin), markers of inflammation, muscle damage and oxidative stress. Heart rate was measured during the race and race time was obtained from the race office. During the short and the long competition two and one finishers, respectively showed serum sodium concentrations >145mmol/L. During the long competition, one athlete showed serum sodium concentrations <135mmol/L. Only during the short competition percent changes in serum sodium concentrations of the finishers were related to percent changes in body mass (r=-0.812, p=0.002), total time (r=-0.608, p=0.047) and training impulse (TRIMP) (r=-0.653, p=0.030). Data show a curvilinear (quadratic) relationship between percent changes in serum sodium concentration and body mass with race time when including all runners (short, long, finishers and non-finishers). The observed prevalence of hypo- and hypernatremia is comparable to literature reports, as is the relationship between serum sodium changes and race time, race intensity and body mass changes of the finishers of the short race. The curvilinear relationship indicates that there might be a turning point of changes in serum sodium and body mass changes after a race time of approximately 20h. Since the turning point is represented mainly by non-finishers, regardless of race duration slight decrease in body mass and a slight increase in serum sodium concentration should be targeted to complete the race. Drinking to the dictate of thirst seems an adequate approach to achieve this goal.

Electrolyte Beverage Intake to Promote Hydration and Maintain Kidney Function in Guatemalan Sugarcane Workers Laboring in Hot Conditions

OBJECTIVES

To evaluate impact of electrolyte supplementation on hydration status and health outcomes in Guatemalan agricultural workers performing heavy work under hot climatic conditions.

METHODS

A 3-week pragmatic trial was conducted with a group of 50 workers during the 2017 to 2018 sugarcane harvest. Workers received an electrolyte hydration intervention during 2 of the 3 weeks. Blood and urine samples were collected each week.

RESULTS

Increased electrolyte intake resulted in less muscle injury. Kidney function was maintained across the intervention period. Workers were adequately hydrated and average electrolyte levels remained in normal ranges. Mild indications of hyponatremia occurred at higher levels of fluid intake.

CONCLUSIONS

This trial demonstrates the feasibility of maintaining workers' electrolyte levels under extremely hot and humid conditions while mitigating muscle injury. Electrolyte supplementation should be added to standard workplace water, rest, and shade interventions to protect workers.

[Exercise-Associated Hyponatremia in Endurance Performance]

Exercise-Associated Hyponatremia in Endurance Performance Abstract. Exercise-associated hyponatremia is defined as a plasma sodium concentration of <135 mmol/l and was first described by Timothy Noakes at the Comrades Marathon in South Africa in the mid-1980s. A decrease in plasma sodium <135 mmol/l occurs with excessive fluid intake. Risk factors include long to very long endurance performance, extreme climatic conditions, female gender and competitions in the USA. Regarding its prevalence by sport, exercise-associated hyponatraemia tends to occur while swimming and running, but rarely when cycling. While mild exercise-associated hyponatremia does not lead to clinical symptoms, severe hyponatremia due to cerebral edema can lead to neurological deficits and even death. The best prevention of exercise-associated hyponatremia is the reduction of fluid intake during exercise.

A case report of hyponatremia after surgery for Conn's adenoma

Primary aldosteronism (PA), also known as Conn's syndrome, is a frequent cause of secondary hypertension. If PA is due to a documented unilateral adrenal adenoma, adrenalectomy is the treatment of choice. Endocrine Society guidelines suggest monitoring potassium after adrenalectomy, while there is no mention of sodium disorders after surgery. Here we report the case of a patient with Conn's syndrome who developed hyponatremia after surgery. This was an unexpected event in the course of the treatment, which sheds light on the fact that low levels of aldosterone strongly influence sodium concentration, and advises clinicians to monitor sodium after adrenalectomy.

Management of Severe Rhabdomyolysis and Exercise-Associated Hyponatremia in a Female with Anorexia Nervosa and Excessive Compulsive Exercising

This case report describes the management of a 49-year-old female with restricting-type anorexia nervosa and excessive compulsive exercising associated with rhabdomyolysis, high levels of serum creatine kinase (CK) (3,238 U/L), and marked hyponatremia (Na⁺: 123 mEq/L) in the absence of purging behaviours or psychogenic polydipsia; it is the first case report to describe exercise-associated hyponatremia in a patient with anorexia nervosa. The patient, who presented with a body mass index (BMI) of 13.4 kg/m², was successfully treated by means of an adapted inpatient version of an enhanced form of cognitive behavioural therapy (CBT-E). Within a few days, careful water restriction, solute refeeding, and the specific cognitive behavioural strategies and procedures used to address the patient's excessive compulsive exercising and undereating produced a marked reduction in CK levels, which normalised within one week. Exercise-associated hyponatremia also gradually improved, with serum sodium levels returning to normal within two weeks. The patient thereby avoided severe complications such as cerebral or pulmonary oedema or acute renal failure and was discharged after 20 weeks of treatment with a BMI of 19.0 kg/m² and improved eating disorder psychopathology.

Special Considerations in Medical Screening for Participants in Remote Endurance Events

As participation at remote endurance events increases, so does the need to screen participants for potentially problematic medical conditions, but this process has been ill-defined to date. This article aims to outline a general approach to screening and discusses common or important medical conditions that may need consideration in the screening process. Medical conditions that are considered low risk may translate to high-risk conditions in the setting of a remote and austere location. Medical directors of remote endurance events should have a familiarity with assessing risks and applying informed consent principles to participation. While there are no specific standards on medical disqualification from an event based on medical history alone, several systematic considerations should be made that allow for an assessment of risk to an individual for a specific event. The medical director and event director, in discussion with the athlete and treating clinician when appropriate, should come to a consensus on participation when high-risk medical conditions become apparent during the screening process. Both modifications and accommodations to participation may be used to mitigate both clinical and medicolegal risk and allow for participation.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

High incidence of hyponatremia in rowers during a four-week training camp

PURPOSE

To investigate the incidence of hyponatremia and its relationship to plasma copeptin, a surrogate marker for arginine vasopressin (AVP) during 28 days of high-volume rowing training.

METHODS

Thirty rowers from the German junior national team (21 male) were studied during a training camp. Serum sodium ([Na(+)]), osmolality, and copeptin were measured before the beginning of the camp (day 0), and at days 7, 13, 18, 24, and 28. Daily fluid intake, body weight, urine parameters, and training volume were recorded.

RESULTS

Seventy percent of the rowers developed hyponatremia at least once. At day 18, training volume and incidence of hyponatremia (43%) were highest. [Na(+)] decreased from 143 ± 9 mmol·L(-1) (day 0) to 135 ± 5 mmol·L(-1) (day 18, P < .01). Hyponatremia was correlated significantly with weight gain compared with the previous day (P < .01). Copeptin decreased from day 0 to 28 (male: 6.7 ± 2.8 to 3.6 ± 1.7 pmol·L(-1); P < .05; female: 4.8 ± 1.1 to 3.2 ± 1.5 pmol·L(-1); P < .05), being only partially suppressed. Relative fluid intake per body surface area increased from day 7 (male: 2.79 ± 0.78 L·m(-2); female: 2.20 ± 0.70 L·m(-2)) to day 28 (3.88 ± 0.69 L·m(2) and 2.65 ± 0.93 L·m(-2); P < .05). No athlete developed symptomatic hyponatremia.

CONCLUSION

Prolonged high-volume rowing training can lead to a high incidence of hyponatremia. Overdrinking and inadequate suppression of AVP contribute to its development.

Fatal water intoxication and cardiac arrest in runners during marathons: prevention and treatment based on validated clinical paradigms

Cerebral edema due to exercise-associated hyponatremia and cardiac arrest due to atherosclerotic heart disease cause rare marathon-related fatalities in young female and middle-aged male runners, respectively. Studies in asymptomatic middle-aged male physician-runners during races identified inflammation due to skeletal muscle injury after glycogen depletion as the shared underlying cause. Nonosmotic secretion of arginine vasopressin as a neuroendocrine stress response to rhabdomyolysis mediates hyponatremia as a variant of the syndrome of inappropriate antidiuretic hormone secretion. Fatal hyponatremic encephalopathy in young female runners was curtailed using emergent infusion of intravenous hypertonic (3%) saline to reverse cerebral edema on the basis of this paradigm. This treatment was arrived at through a consensus process within the medical community. An increasing frequency of cardiac arrest and sudden death has been identified in middle-aged male runners in 2 studies since the year 2000. Same-aged asymptomatic male physician-runners showed post-race elevations in interleukin-6 and C-reactive protein, biomarkers that predict acute cardiac events in healthy persons. Hypercoagulability with in vivo platelet activation and release of cardiac troponin and N-terminal pro-brain natriuretic peptide were also observed post-race in these same subjects. High short-term risk for atherothrombosis during races as shown by stratification of biomarkers in asymptomatic men may render nonobstructive coronary atherosclerotic plaques vulnerable to rupture. Pre-race aspirin use in this high-risk subgroup is prudent according to conclusive evidence for preventing first acute myocardial infarctions in same-aged healthy male physicians. On the basis of validated clinical paradigms, taking a low-dose aspirin before a marathon and drinking to thirst during the race may avert preventable deaths in susceptible runners.

Wilderness Medical Society practice guidelines for treatment of exercise-associated hyponatremia: 2014 update

Exercise-associated hyponatremia (EAH) is defined by a serum or plasma sodium concentration below the normal reference range of 135 mmol/L that occurs during or up to 24 hours after prolonged physical activity. It is reported to occur in individual physical activities or during organized endurance events conducted in austere environments in which medical care is limited and often not available, and patient evacuation to definitive care is often greatly delayed. Rapid recognition and appropriate treatment are essential in the severe form to ensure a positive outcome. Failure in this regard is a recognized cause of event-related fatality. In an effort to produce best practice guidelines for EAH in the austere environment, the Wilderness Medical Society convened an expert panel. The panel was charged with the development of evidence-based guidelines for management of EAH. Recommendations are made regarding the situations when sodium concentration can be assessed in the field and when these values are not known. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks/burdens for each parameter according to the methodology stipulated by the American College of Chest Physicians. This is an updated version of the original WMS Practice Guidelines for Treatment of Exercise-Associated Hyponatremia published in Wilderness & Environmental Medicine 2013;24(3):228-240.

Incidence of Exercise-Associated Hyponatremia and Its Association With Nonosmotic Stimuli of Arginine Vasopressin in the GNW100s Ultra-endurance Marathon

OBJECTIVES

(1) To examine the incidence of exercise-associated hyponatremia (EAH) during and after an ultramarathon and (2) to evaluate hypothesized nonosmotic stimuli [interleukin-6 (IL-6), hypoglycemia, ambient temperature] with arginine vasopressin (AVP) concentrations in hyponatremic versus normonatremic runners.

DESIGN

Prospective cohort study.

SETTING

The Great North Walk 100s ultramarathons.

PARTICIPANTS

Fifteen runners participated in either 103.7- or 173.7-km ultramarathons.

MAIN OUTCOME MEASURES

Serum sodium concentration ([Na]) and AVP concentration. Secondary outcome measures included IL-6, blood glucose, ambient temperature, weight change, fluid consumption, and use of nonsteroidal anti-inflammatory drugs (NSAIDs).

RESULTS

Postrace EAH incidence was 4 of 15 runners, whereas EAH incidence at any point during the race was in 10 of 15 runners. A significant positive correlation was noted between AVP and IL-6 (r = 0.31, P < 0.05) but not between AVP and blood glucose (r = 0.09, nonsignificant) or ambient temperature (r = -0.12, NS). Subgroup analysis revealed that the correlation between AVP and IL-6 was significant in hyponatremic (r = 0.37, P < 0.05) but not normonatremic runners (r = 0.31, NS). Hyponatremic runners lost less weight than normonatremic runners (2.5 vs. 3.7 kg, P < 0.05, respectively) despite similar fluid consumption. Seven of 10 hyponatremic runners consumed NSAIDs versus 0 of 5 normonatremic runners.

CONCLUSIONS

Exercise-associated hyponatremia incidence mid-race is higher than postrace, suggesting that 40% of runners are able to self-correct low serum [Na] status during an ultramarathon. Interleukin-6 seems to be the main nonosmotic stimulus associated with AVP in hyponatremic runners. Nonsteroidal anti-inflammatory ingestion is more common in hyponatremic versus normonatremic runners.

CLINICAL RELEVANCE

Exercise-associated hyponatremia associated with nonosmotic AVP secretion may be more common during ultramarathon races without discriminatory clinical symptomatology.

Rhabdomyolysis and exercise-associated hyponatremia in ultra-bikers and ultra-runners

Background

Exercise-associated hyponatremia (EAH), rhabdomyolysis and renal failure appear to be a unique problem in ultra-endurance racers.

Methods

We investigated the combined occurrence of EAH and rhabdomyolysis in seven different ultra-endurance races and disciplines (i.e. multi-stage mountain biking, 24-h mountain biking, 24-h ultra-running and 100-km ultra-running).

Results

Two (15.4 %) ultra-runners (man and woman) from hyponatremic ultra-athletes (n = 13) and four (4 %) ultra-runners (four men) from the normonatremic group (n = 100) showed rhabdomyolysis following elevated blood creatine kinase (CK) levels > 10,000 U/L without the development of renal failure and the necessity of a medical treatment. Post-race creatine kinase, plasma and urine creatinine significantly increased, while plasma [Na⁺] and creatine clearance decreased in hyponatremic and normonatremic athletes, respectively. The percentage increase of CK was higher in the hyponatremic compared to the normonatremic group (P < 0.05). Post-race CK levels were higher in ultra-runners compared to mountain bikers (P < 0.01), in faster normonatremic (P < 0.05) and older and more experienced hyponatremic ultra-athletes (P < 0.05). In all finishers, pre-race plasma [K⁺] was related to post-race CK (P < 0.05).

Conclusions

Hyponatremic ultra-athletes tended to develop exercise-induced rhabdomyolysis more frequently than normonatremic ultra-athletes. Ultra-runners tended to develop rhabdomyolysis more frequently than mountain bikers. We found no association between post-race plasma [Na⁺] and CK concentration in both hypo- and normonatremic ultra-athletes.

Employment of vasopressin receptor antagonists in management of hyponatraemia and volume overload in some clinical conditions

WHAT IS KNOWN AND OBJECTIVE

Hyponatraemia, the most common electrolyte imbalance occurring in hospitalized subjects, is usually classified as hypovolaemic, euvolaemic or hypervolaemic. Hyponatraemia is a predictor of death among subjects with chronic heart failure and cirrhosis. The inappropriate secretion of the antidiuretic hormone (AVP) seems to be of pivotal importance in the decline of serum sodium concentration in these clinical conditions. The objective of this review was to summarize recent progress in management of hyponatraemia in SIADH, cirrhosis and heart failure.

METHODS

Literature searches were conducted on the topics of hyponatraemia and vasopressin receptor antagonists, using PubMed, pharmaceutical company websites and news reports. The information was evaluated for relevance and quality, critically assessed and summarized.

RESULTS AND DISCUSSION

The initial treatment of severe hyponatraemia is directed towards the prevention or management of neurological manifestations and consists of an intravenous infusion of hypertonic saline. Fluid restriction is indicated in oedematous states. Diuretics alone or in combination with other specific drugs remain the main strategy in the management of volume overload in heart failure. In resistant cases, ultrafiltration can lead to effective removal of isotonic fluid preventing new episodes of decompensation; however, aquapheresis is associated with increased costs and other limits. In several trials, the efficacy of vasopressin receptor antagonists in euvolaemic patients (inappropriate antidiuretic hormone secretion) or in hypervolaemic hyponatraemia (chronic heart failure, cirrhosis) has been evaluated. It was found that vaptans, which promote aquaresis, were superior to a placebo in raising and maintaining serum sodium concentrations in these subjects.

WHAT IS NEW AND CONCLUSIONS

Combined with conventional therapy, vasopressin receptor antagonists (AVP-R antagonists) are able to increase the excretion of electrolyte-free water and the sodium concentration. Further studies are needed to assess efficacious outcomes of aquaresis compared with aquapheresis and with conventional therapy.

Physiopathological, Epidemiological, Clinical and Therapeutic Aspects of Exercise-Associated Hyponatremia

Exercise-associated hyponatremia (EAH) is dilutional hyponatremia, a variant of inappropriate antidiuretic hormone secretion (SIADH), characterized by a plasma concentration of sodium lower than 135 mEq/L. The prevalence of EAH is common in endurance (<6 hours) and ultra-endurance events (>6 hours in duration), in which both athletes and medical providers need to be aware of risk factors, symptom presentation, and management. The development of EAH is a combination of excessive water intake, inadequate suppression of the secretion of the antidiuretic hormone (ADH) (due to non osmotic stimuli), long race duration, and very high or very low ambient temperatures. Additional risk factors include female gender, slower race times, and use of nonsteroidal anti-inflammatory drugs. Signs and symptoms of EAH include nausea, vomiting, confusion, headache and seizures; it may result in severe clinical conditions associated with pulmonary and cerebral edema, respiratory failure and death. A rapid diagnosis and appropriate treatment with a hypertonic saline solution is essential in the severe form to ensure a positive outcome.

Hyponatremia-associated rhabdomyolysis following exercise in an adolescent with cystic fibrosis

Adolescents with well-controlled cystic fibrosis, including good lung function and appropriate growth, commonly participate in competitive athletic activities. We present the case of an adolescent male with cystic fibrosis, hyponatremia, dehydration, and rhabdomyolysis after participating in football practice on a summer morning. The patient presented with severe myalgia and serum sodium of 129 mmol/L, chloride 90 mmol/L, and creatine phosphokinase 1146 U/L. Aggressive hydration with intravenous 0.9% saline resulted in clinical improvement with no renal or muscular sequelae. Health care providers need to educate patients with cystic fibrosis about maintaining adequate hydration and sodium repletion during exercise. Research is needed regarding the appropriate amount and composition of oral rehydration fluids in exercising individuals with cystic fibrosis, as the physiology encountered in these patients provides a unique challenge to maintaining electrolyte balance and stimulation of thirst.

Pheidippides redux: reducing risk for acute cardiac events during marathon running

Prolonged strenuous exercise such as marathon running transiently increases the absolute and relative risk for sudden cardiac death. A 17-fold increase in the latter over resting baseline in previously sedentary middle-aged men is reduced due to cardioprotection from training in experienced marathon runners. Exertional rhabdomyolysis as a common occurrence during the race is accompanied by neutrophilia and elevated biomarkers of inflammation, including interleukin-6 and C-reactive protein. A hemostatic imbalance with prothrombotic effects includes in vivo platelet activation during the race. Suggesting a pathogenic role for these findings, plaque rupture due to atherothrombosis triggers acute exertional cardiac events, including sudden death, in low-risk runners as in high-risk patients such as those with diabetes mellitus. Strategies including prophylactic aspirin are considered to decrease the risk for acute cardiac events.

Hemolysis induced by an extreme mountain ultra-marathon is not associated with a decrease in total red blood cell volume

Prolonged running is known to induce hemolysis. It has been suggested that hemolysis may lead to a significant loss of red blood cells; however, its actual impact on the erythrocyte pool is unknown. Here, we test the hypothesis that prolonged running with high hemolytic potential decreases total red blood cell volume (RCV). Hemolysis (n = 22) and RCV (n = 19) were quantified in ultra-marathon runners before and after a 166-km long mountain ultra-endurance marathon (RUN) with 9500 m of altitude gain/loss. Assessment of total hemoglobin mass (Hbmass) and RCV was performed using a carbon monoxide rebreathing technique. RUN induced a marked acute-phase response and promoted hemolysis, as shown by a decrease in serum haptoglobin (P < 0.05). Elevated serum erythropoietin concentration and reticulocyte count after RUN were indicative of erythropoietic stimulation. Following RUN, runners experienced hemodilution, mediated by a large plasma volume expansion and associated with a large increase in plasma aldosterone. However, neither Hbmass nor RCV were found to be altered after RUN. Our findings indicate that mechanical/physiological stress associated with RUN promotes hemolysis but this has no impact on total erythrocyte volume. We therefore suggest that exercise 'anemia' is entirely due to plasma volume expansion and not to a concomitant decrease in RCV.

Marathon runner with acute hyponatremia: a neurological disorder

We report the case of an athletic 49-year-old female who has run the 2011 Marathon of Paris and was addressed to the hospital for a confusion. The investigations revealed a cerebral edema complicating a severe hyponatremia secondary to an exercise-associated hyponatremia (EAH). Using 3% hypertonic saline solution, the evolution the patient rapidly improve allowing discharge after 7 days. We then discuss the importance of EAH in long-term efforts.

Early subclinical increase in pulmonary water content in athletes performing sustained heavy exercise at sea level: ultrasound lung comet-tail evidence

Whether prolonged strenuous exercise performed by athletes at sea level can produce interstitial pulmonary edema is under debate. Chest sonography allows to estimate extravascular lung water, creating ultrasound lung comet-tail (ULC) artifacts. The aim of the study was to determine whether pulmonary water content increases in Ironmen (n = 31) during race at sea level and its correlation with cardiopulmonary function and systemic proinflammatory and cardiac biohumoral markers. A multiple factor analysis approach was used to determine the relations between systemic modifications and ULCs by assessing correlations among variables and groups of variables showing significant pre-post changes. All athletes were asymptomatic for cough and dyspnea at rest and after the race. Immediately after the race, a score of more than five comet tail artifacts, the threshold for a significant detection, was present in 23 athletes (74%; 16.3 ± 11.2; P < 0.01 ULC after the race vs. rest) but decreased 12 h after the end of the race (13 athletes; 42%; 6.3 ± 8.0; P < 0.01 vs. soon after the race). Multiple factor analysis showed significant correlations between ULCs and cardiac-related variables and NH(2)-terminal pro-brain natriuretic peptide. Healthy athletes developed subclinical increase in pulmonary water content immediately after an Ironman race at sea level, as shown by the increased number of ULCs related to cardiac changes occurring during exercise. Hemodynamic changes are one of several potential factors contributing to the mechanisms of ULCs.

Pulmonary edema in healthy subjects in extreme conditions

There are several pieces of evidence showing occurrence of pulmonary edema (PE) in healthy subjects in extreme conditions consisting of extreme psychophysical demand in normal environment and psychophysical performances in extreme environment. A combination of different mechanisms, such as mechanical, hemodynamic, biochemical, and hypoxemic ones, may underlie PE leading to an increase in lung vascular hydrostatic pressure and lung vascular permeability and/or a downregulation of the alveolar fluid reabsorption pathways. PE can be functionally detected by closing volume measurement and lung diffusing capacity test to different gases or directly visualized by multiple imaging techniques. Among them chest ultrasonography can detect and quantify the extravascular lung water, creating “comet-tail” ultrasound artefacts (ULCs) from water-thickened pulmonary interlobular septa. In this paper the physiopathological mechanisms of PE, the functional and imaging techniques applied to detect and quantify the phenomenon, and three models of extreme conditions, that is, ironman athletes, climbers and breath-hold divers, are described.

Hyponatremia and inflammation: the emerging role of interleukin-6 in osmoregulation

Although hyponatremia is a recognized complication of several inflammatory diseases, its pathophysiology in this setting has remained elusive until recently. A growing body of evidence now points to an important role for interleukin-6 in the non-osmotic release of vasopressin. Here, we review this evidence by exploring the immuno-neuroendocrine pathways connecting interleukin-6 with vasopressin. The importance of these connections extends to several clinical scenarios of hyponatremia and inflammation, including hospital-acquired hyponatremia, postoperative hyponatremia, exercise-associated hyponatremia, and hyponatremia in the elderly. Besides insights in pathophysiology, the recognition of the propensity for antidiuresis during inflammation is also important with regard to monitoring patients and selecting the appropriate intravenous fluid regimen, for which recommendations are provided.

Exercise-associated hyponatremia: the influence of pre-exercise carbohydrate status combined with high volume fluid intake on sodium concentrations and fluid balance

To evaluate the effect of hydration and carbohydrate (CHO) status on plasma sodium, fluid balance, and regulatory factors (IL-6 & ADH) during and after exercise; 10 males completed the following conditions: low CHO, euhydrated (fluid intake = sweat loss) (LCEH); low CHO, dehydrated (no fluid) (LCDH); high CHO, euhydrated (HCEH); and high CHO, dehydrated (HCDH). Each trial consisted of 90-min cycling at 60% VO(2) max in a 35°C environment followed by 3-h rehydration (RH). During RH, subjects received either 150% of sweat loss (LCDH & HCDH) or an additional 50% of sweat loss (LCEH and HCEH). Blood was analyzed for glucose, IL-6, ADH, and Na(+). Post-exercise Na(+) was greater (p < 0.001) for LCDH and HCDH (141.7 + 0.72 and 141.6 + 0.4 mM) versus LCEH and HCEH (136.4 + 0.6 and 135.9 + 0.3 mM). Post-exercise IL-6 was similar in all conditions, and post-exercise ADH was greater (p = 0.01) in dehydrated versus euhydrated conditions. The rate of urine production was greater in HCEH (7.59 + 3.0 mL/min) compared to all other conditions (3.86 + 2.2, 5.29 + 3.1, and 2.96 + 1.1 mL/min for LCDH, LCEH, and HCDH, respectively). Despite CHO and hydration manipulations, no regulatory effects of IL-6 and ADH on plasma [Na(+)] were observed. With euhydration during exercise and additional fluid consumed during recovery, a high-CHO status increased urinary output during recovery, and it decreased the frequency of hyponatremia (Na(+) < 135 mM). Therefore, a high-CHO status may provide some protection against exercise-associated hyponatremia.

Arginine vasopressin, fluid balance and exercise: is exercise-associated hyponatraemia a disorder of arginine vasopressin secretion?

The ability of the human body to regulate plasma osmolality (POsm) within a very narrow and well defined physiological range underscores the vital importance of preserving water and sodium balance at rest and during exercise. The principle endocrine regulator of whole body fluid homeostasis is the posterior pituitary hormone, arginine vasopressin (AVP). Inappropriate AVP secretion may perpetuate either slow or rapid violation of these biological boundaries, thereby promoting pathophysiology, morbidity and occasional mortality. In the resting state, AVP secretion is primarily regulated by changes in POsm (osmotic regulation). The osmotic regulation of AVP secretion during exercise, however, may possibly be enhanced or overridden by many potential non-osmotic factors concurrently stimulated during physical activity, particularly during competition. The prevalence of these highly volatile non-osmotic AVP stimuli during strenuous or prolonged physical activity may reflect a teleological mechanism to promote water conservation during exercise. However, non-osmotic AVP secretion, combined with high fluid availability plus sustained fluid intake (exceeding fluid output), has been hypothesized to lead to an increase in both the incidence and related deaths from exercise-associated hyponatraemia (EAH) in lay and military populations. Inappropriately, high plasma AVP concentrations ([AVP](p)) associated with low blood sodium concentrations facilitate fluid retention and sodium loss, thereby possibly reconciling both the water intoxication and sodium loss theories of hyponatraemia that are currently under debate. Therefore, given the potential for a variety of exercise-induced non-osmotic stimuli for AVP secretion, hydration strategies must be flexible, individualized and open to change during competitive events to prevent the occurrence of rare, but life-threatening, EAH. This review focuses on the potential osmotic and non-osmotic stimuli to AVP secretion that may affect fluid homeostasis during physical activity. Recent laboratory and field data support: (i) stimulatory effects of exercise intensity and duration on [AVP](p); (ii) possible relationships between changes in POsm with changes in both sweat and urinary osmolality; (iii) alterations in the AVP osmoregulatory set-point by sex steroid hormones; (iv) differences in [AVP](p) in trained versus untrained athletes; and (v) potential inter-relationships between AVP and classical (aldosterone, atrial natriuretic peptide) and non-classical (oxytocin, interleukin-6) endocrine mediators. The review concludes with a hypothesis on how sustained fluid intakes beyond the capacity for fluid loss might possibly facilitate the development of hyponatraemia if exercise-induced non-osmotic stimuli override 'normal' osmotic suppression of AVP when hypo-osmolality exists.

Exercise-associated hyponatremia during winter sports

Exercise-associated hyponatremia (EAH) is hyponatremia that occurs <or= 24 hours after prolonged physical activity. It is a potentially serious complication of marathons, triathlons, and ultradistance events, and can occur in hot and cold environments. Clear evidence indicates that EAH is a dilutional hyponatremia caused by excessive fluid consumption and the inappropriate release of arginine vasopressin. Cerebral and pulmonary edema can cause serious signs and symptoms, including altered mental status, respiratory distress, seizures, coma, and death. Rapid diagnosis and urgent treatment with hypertonic saline is necessary to prevent severe complications or death. Prevention is based on educating athletes to avoid excessive drinking before, during, and after exercise.

Pulmonary oedema and hyponatraemia after an ironman triathlon

A 36-year-old man presented with symptoms of acute pulmonary oedema at the conclusion of the Australian ironman triathlon. He was alert, orientated, with an oxygen saturation of 75% on room air. Chest examination revealed bilateral basal crepitations. Serum sodium was 120 mmol/L and chest x ray revealed bilateral basal opacities. He was treated for acute pulmonary oedema with prompt improvement and given 200 ml of intravenous hypertonic saline followed by normal saline. Serum sodium decreased to 117 mmol/L and 30 hours after presentation he had a seizure. He fully recovered and was discharged 5 days after admission. This case highlights that exercise-associated hyponatraemia and pulmonary oedema are still not widely understood and there is still a reluctance to treat hyponatraemia aggressively with ongoing hypertonic saline.

Case report: exercise-associated hyponatremia with rhabdomyolysis during endurance exercise

Exercise-associated hyponatremia (EAH) has been well described in the literature, and its pathogenesis has been elucidated. The most common presenting symptoms of EAH are confusion or severe alterations in mental status. Although rhabdomyolysis in association with hyponatremia has been described in other settings, only 1 case of EAH associated with rhabdomyolysis at presentation has been previously described. In this article, we report on the occurrence of EAH with rhabdomyolysis in 4 athletes participating in the West Highland Way Race, a 95-mile endurance foot race. The pathogenesis of this association is described with implications for therapy.

Fitness alters fluid regulatory but not behavioural responses to hypohydrated exercise

Dehydration is typical during prolonged exercise. Because training stimulates numerous adaptations, some involving fluid regulation, it is conceivable that training involves adaptations to dehydration. This study tested the hypothesis that trained individuals have altered fluid regulatory, but not behavioural or perceptual responses to exercise when hypohydrated. Six trained (V.O2 peak: 65+/-8 mL kg(-1) min(-1)) and six untrained (V.O2 peak: 45+/-4 mL kg(-1) min(-1)) males cycled for 40 min at 70%V.O2 peak, once whilst euhydrated (EUH) and once whilst hypohydrated by ~2% body mass (HYPO), before a 40-min performance trial with euhydration (in EUH) or ad libitum drinking (in HYPO), in temperate conditions (24.3 degrees C, 50% rh). Baseline hydration was achieved by complete or partial rehydration from exercise+heat stress on the previous evening. Body mass was reduced (-1.8+/-0.1%) and plasma osmolality was increased (5+/-1 mosmol kg(-1)) similarly between fitness groups in HYPO compared to EUH (P<0.05). During exercise, plasma [AVP] rose more in HYPO than EUH; the elevation was greater in the Untrained (4.1+/-1.7 vs. 2.0+/-0.8 pmol L(-1), P<0.01) than Trained (1.4+/-0.6 vs. 1.1+/-0.5 pmol L(-1), P<0.01; P=0.02). Increases in plasma [AVP] relative to osmolality were higher in Untrained than Trained (0.47+/-0.06 vs. 0.025+/-0.05 pmol mosmol(-1), P=0.03). Fitness groups had equivalent thirst ratings during fixed exercise but Trained were thirstier than Untrained when self regulating in HYPO (4.0+/-1.5 vs. 2.7+/-1.2; P=0.05); thus Trained tended to consume more fluid (1.20+/-0.16 vs. 0.88+/-0.16 L; P=0.19), but maintained similar hypohydration consistent with their greater sweat rate during HYPO. In conclusion, aerobic fitness attenuates the neuroendocrine ([AVP]) response to hypohydrated exercise, but not perceptual (thirst) or behavioural (ad libitum drinking) responses.

Osmotic and nonosmotic regulation of arginine vasopressin during prolonged endurance exercise

CONTEXT

Although the primary cause of exercise-associated hyponatremia (EAH) is relative overconsumption of fluids beyond the kidneys' ability to excrete excess fluid, the mechanisms limiting maximum renal excretory ability during exercise remain to be elucidated.

OBJECTIVE

The objective of the study was to: 1) perform a comprehensive evaluation of the endocrine secretion of pituitary, natriuretic and adrenal steroid hormones, and cytokines immediately before and after running an ultramarathon; and 2) evaluate the relationship between osmotic and nonosmotic stimuli to arginine vasopressin (AVP) secretion within the overall context of assessing the hormonal regulation of fluid balance during prolonged endurance exercise.

DESIGN

This was an observational study.

SETTING

The study setting was a 56-km ultramarathon.

PARTICIPANTS

Eighty-two runners participated in the study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

Plasma sodium concentration [Na(+)] and plasma volume [(AVP)(p)] were measured.

RESULTS

Fluid homeostasis during exercise (356 +/- 4 min) was maintained with ad libitum fluid intakes. [Na(+)] was maintained from before the race (139.3 +/- 0.3 mmol/liter) to after the race (138.1 +/- 0.4 mmol/liter) with a significant decrease in plasma volume (-8.5 +/- 0.1%, P < 0.01). Increases in the plasma (AVP)(p) (3.9-fold), oxytocin (1.9-fold), brain natriuretic peptide (4.5-fold), and IL-6 (12.5-fold) were highly significant (P < 0.0001). Changes in brain natriuretic peptide, oxytocin, and corticosterone were associated with 47% of the variance noted in (AVP)(p) and 13% of the variance in plasma [Na(+)] in pathway analyses.

CONCLUSIONS

(AVP)(p) was markedly elevated after the ultramarathon despite unchanged plasma [Na(+)](.) Therefore, an inability to maximally suppress (AVP)(P) during exercise as a result of nonosmotic stimulation of AVP secretion may contribute to the pathogenesis of exercise-associated hyponatremia if voluntary fluid intake were to exceed fluid output.

Hyponatremia in psychiatric patients: update on evaluation and management

BACKGROUND

Hyponatremia (serum sodium concentration < 136 mEq/L) is a prevalent and potentially dangerous medical comorbidity in psychiatric patients.

METHODS

MEDLINE was used to identify peer-reviewed publications that described the role of arginine vasopressin (AVP) in the pathogenesis of hyponatremia, the presentation and treatment of hyponatremia in psychiatric patients, and promising new treatment options.

RESULTS

Polydipsia may lead to hyponatremia in patients with schizophrenia, which is mediated, in part, by a reduced osmotic threshold for the release of AVP and by a defect in the osmoregulation of thirst. Acute-onset hyponatremia may require emergent treatment with hypertonic (3%) saline, whereas chronic cases mandate gradual correction to minimize the risk of osmotic demyelination. The AVP-receptor antagonists, including conivaptan, tolvaptan, lixivaptan, and satavaptan, represent a therapeutic advance in the treatment of dilutional hyponatremia.

CONCLUSION

Based on the role of AVP in the development of hyponatremia, further studies are warranted to determine the efficacy of the AVP-receptor antagonists in psychiatric patients with hyponatremia.

Athletic performance and serial weight changes during 12- and 24-hour ultra-marathons

OBJECTIVE

The principal objective of this study was to evaluate serial weight changes in athletes during 12- and 24-hour ultra-marathons and to correlate these changes with athletic performance, namely the distance covered.

DESIGN

This was a prospective study.

SETTING

The 2003 Soochow University international ultra-marathon.

PARTICIPANTS

Fifty-two race participants.

INTERVENTIONS

12- or 24-hour ultra-marathon.

MAIN OUTCOME MEASUREMENTS

Body weight changes were measured before, at 4-hour intervals during, and immediately after the 12- and 24-hour races.

RESULTS

Significant overall decreases in body weight were apparent at the conclusion of both races. The mean relative body weight change after the 12-hour race was -2.89 +/- 1.56%, ranging from 0 to 6.5%. The mean relative body weight change after the 24-hour race was -5.05 +/- 2.28%, ranging from -0.77% to -11.40%. Of runners in the 24-hour race, 26% lost greater than 7% of baseline body weight during the race. During both the 12- and 24-hour races, the greatest weight change (decrease) occurred during the first 4 hours. Weight remained relatively stable after 8 hours, although a further decrease was apparent between 16 and 20 hours in the 24-hour participants. Weight change had no bearing on performance in the 12-hour race, whereas weight loss was positively associated with performance in the 24-hour race.

CONCLUSIONS

Our findings demonstrate that the majority of weight decrease/dehydration in both the 12- and 24-hour races occurred during the first 8 hours. Hence, to maintain body weight, fluid intake should be optimized in the first 8 hours for both 12- and 24-hour runners and in 16 to 20 hours for 24-hour marathon runners.

The Sensory Psychobiology of Thirst and Salt Appetite

Thirst and the hunger for sodium containing fluids and food (i.e., sodium appetite) are the consequences of the generation of unique central nervous system states. Altered body fluid homeostasis produces sensory and perceptional changes that arise from signals generated in the body that serve as indices of body fluid balance and distribution. These signaling mechanisms activate networks of brain neurons that use specific neurochemicals to communicate between cells and process information. The brain integrates information derived from various bodily sources so that thirst and sodium appetite are in a true sense the synthetic products of the nervous system. In recent years much has been learned about the stimuli and receptor systems involved in signaling the brain to reflect the status of bodily fluids and about the central neural substrates that process such inputs to generate thirst and sodium appetite. Knowledge about the sensory nature of thirst and sodium appetite provides a basis for understanding the biological constraints under which thirst and sodium appetite operate. This information is important for appreciating the extent to which thirst and sodium appetite motivational states and behaviors can be relied on to maintain and repair disruptions of body fluid homeostasis.

Hyponatremia in marathon runners due to inappropriate arginine vasopressin secretion

PURPOSE

Exercise-associated hyponatremia (EAH), as defined by a blood sodium concentration [Na+] less than 135 mmol/L, may lead to hypotonic encephalopathy with fatal cerebral edema. Understanding the pathogenetic role of antidiuresis may lead to improved strategies for prevention and treatment.

METHODS

Normonatremic marathon runners were tested pre- and post-race for creatine kinase, interleukin-6, cortisol, prolactin, and arginine vasopressin. Similar testing also was carried out in runners with encephalopathy caused by EAH, including 2 cases with fatal cerebral edema.

RESULTS

Normonatremic runners (n = 33; 2001) with a mean 3% decrease in body weight showed a 40-fold increase in interleukin-6 (66.6 +/- 11.9 pg/mL from 1.6 +/- 0.5 pg/mL, P = .001), which was significantly correlated with increases in creatine kinase (r = 0.88, P = <.0001), cortisol (r = 0.70, P = .0003), and prolactin (r = 0.67, P <.007), but not arginine vasopressin (r = 0.44, P = .07). Collapsed runners with EAH (n = 22; 2004) showed a mean blood urea nitrogen less than 15 mg/dL with measurable plasma levels of arginine vasopressin (>0.5 pg/mL) in 43% of cases. Two marathon runners with fatal cerebral edema additionally showed less than maximally dilute urines (>100 mmol/kg/H2O) and urine [Na+] greater than 25 mEq/L.

CONCLUSIONS

Cases of EAH fulfill the essential diagnostic criteria for the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Runners with hypotonic encephalopathy at subsequent races were treated with intravenous hypertonic (3%) saline on the basis of this paradigm, which resulted in rapid clinical improvement without adverse effects. Release of muscle-derived interleukin-6 may play a role in the nonosmotic secretion of arginine vasopressin, thereby linking rhabdomyolysis to the pathogenesis of EAH.

Novel risk factors for hospital-acquired hyponatraemia: a matched case-control study

BACKGROUND

Hospital-acquired hyponatraemia is a common and potentially serious condition. Risk factors for hospital-acquired hyponatraemia have not been studied in a controlled fashion. Methods From 1501 patients in whom serum sodium (S(Na)) was determined, 50 cases with hospital-acquired hyponatraemia (in-hospital decrease in S(Na)>or= 7 mmol/l to < 136 mmol/l) were identified. They were matched by age, gender and department to 69 normonatraemic controls.

RESULTS

In the 50 cases, S(Na) fell from 141 +/- 2 to 130 +/- 4 mmol/l, while controls remained normonatraemic. During the development of hyponatraemia, C-reactive protein (CRP) increased in cases (median from 23 to 146 mg/l), whereas it decreased in controls (median from 31 to 24 mg/l, P = 0.008). Additional factors associated with hospital-acquired hyponatraemia included diabetes mellitus (16/50 vs. 10/69, P = 0.009) and the use of insulin (12/50 vs. 4/69, P = 0.007), antibiotics (41/50 vs. 38/69, P = 0.006) and opioids (32/50 vs. 27/69, P = 0.005). Multivariate conditional logistic regression showed that the use of insulin [odds ratio (OR) 10.5, 95% confidence interval (CI) 1.5-72.4], antibiotics (OR 4.5, 95% CI 1.4-14.6) and opioids (OR 2.9, 95% CI 1.1-7.8) was also independently associated with hospital-acquired hyponatraemia. Mortality (6/50 vs. 1/69, P = 0.04) and intensive care admission (15/50 vs. 7/69, P = 0.008) were higher in cases.

CONCLUSIONS

An increase in CRP and the use of insulin, antibiotics and opioids are novel risk factors for hospital-acquired hyponatraemia. These factors represent interesting new clues regarding the pathophysiology of hospital-acquired hyponatraemia, suggesting that the acute-phase response, pain and/or direct drug effects could be involved in the release of antidiuretic hormone.

Hypertonic (3%) Sodium Chloride for Emergent Treatment of Exercise-Associated Hypotonic Encephalopathy

Exercise-associated hyponatraemia (EAH) is an acute-onset imbalance in the tonicity of extracellular fluids during or after endurance exercise which results in a blood sodium concentration <135 mmol/L. Both excessive fluid intake and a concurrent decrease in urine formation contribute to this rapid-onset, predominantly dilutional, decrease in serum sodium, which can result in life-threatening pulmonary and cerebral oedema. Marathon runners with hypotonic encephalopathy related to EAH, including two cases with fatal cerebral oedema, demonstrated non-osmotic secretion of arginine vasopressin and fulfilled the essential diagnostic criteria for the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The pathophysiology of SIADH as the proximate cause of EAH accounts for otherwise puzzling clinical observations such as cases occurring after only moderate fluid intake or presenting hours after races. This formulation provides a framework for enhancing prevention by monitoring weight changes during races to detect positive fluid balance before the onset of mental status changes. Most importantly, SIADH supports a strategy for use of oral and intravenous hypertonic solutions, including 3% sodium chloride, for the emergent treatment of moderate and life-threatening symptoms of hypotonic encephalopathy, respectively.

Exercise-associated hyponatremia

Exercise-associated hyponatremia has been described after sustained physical exertion during marathons, triathlons, and other endurance athletic events. As these events have become more popular, the incidence of serious hyponatremia has increased and associated fatalities have occurred. The pathogenesis of this condition remains incompletely understood but largely depends on excessive water intake. Furthermore, hormonal (especially abnormalities in arginine vasopressin secretion) and renal abnormalities in water handling that predispose individuals to the development of severe, life-threatening hyponatremia may be present. This review focuses on the epidemiology, pathogenesis, and therapy of exercise-associated hyponatremia.

Nephrogenic syndrome of inappropriate antidiuresis: a novel disorder in water balance in pediatric patients

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common cause of hyponatremia. We report findings in 2 unrelated male infants whose clinical presentation and laboratory findings were consistent with SIADH, but who exhibited unmeasurable arginine vasopressin (AVP) levels on repeated occasions. We hypothesized that these infants had a novel gain of function defect in the AVP-signaling pathway. DNA sequencing of each patient's vasopressin V2 receptor (V2R) gene identified mutations (R137C or R137L) in each. R137H mutations have been reported previously to cause nephrogenic diabetes insipidus. To further characterize the effects of these mutations, we re-created each mutation by site-directed mutagenesis in a vasopressin V2R expression vector and cotransfected COS-7 cells with wild-type and mutant vasopressin V2R vectors and a cyclic adenosine monophosphate-responsive luciferase reporter plasmid. The luciferase activity was induced 7.5-fold (R137L mutant; P = 0.0037) and 4-fold (R137C mutant; P = 0.013) more than the wild-type vasopressin V2R, which is the empty vector or the inactivating R137H mutant. This novel gain of function mutation in the vasopressin V2R can cause constitutive activation of the receptor and resultant hyponatremia. These findings represent a previously unrecognized genetic disease, which was designated as nephrogenic syndrome of inappropriate antidiuresis. A number of questions have emerged, including the following: (1) What is the frequency? (2) Are there nonrenal manifestations? (3) Are heterozygotes affected? (4) What is the optimal therapy? and (5) How do these mutations cause constitutive activation of the receptor?