Diagnosis of Swimming Induced Pulmonary Edema-A Review

Swimming-Induced Pulmonary Edema Masquerading as Acute Respiratory Distress Syndrome: A Case Report

Immersion pulmonary edema, also known as swimming-induced pulmonary edema (SIPE), manifests with cough, dyspnea, hemoptysis, and hypoxemia from flash pulmonary edema after surface swimming, often in healthy young individuals with no predisposing conditions. SIPE commonly resolves spontaneously within 24-48 hours but can be fatal. Post-mortem findings demonstrate heavy, edematous lungs and frothy airways. Although these pathologic findings are like those seen in patients with drowning, SIPE, by definition, is associated with pulmonary edema that develops with a closed glottis without drowning/aspiration. However, patients who develop SIPE during swimming could lose consciousness and drown. Its pathophysiology is poorly understood, and the medical literature infrequently describes SIPE. Due to the multifactorial and complex pathophysiology and the scarcity of medical literature describing SIPE, the diagnosis could be difficult at presentation. This case report elaborates on diagnosing and treating swimming-induced pulmonary edema in a hypertensive and obese female who presented to our emergency room with an acute onset of shortness of breath after recreational swimming in a pool.

Characterizing Immersion Pulmonary Edema (IPE): A Comparative Study of Military and Recreational Divers

BACKGROUND

Immersion Pulmonary Edema (IPE) is a common and potentially serious diving accident that can have significant respiratory and cardiac consequences and, in some cases, be fatal. Our objective was to characterize cases of IPE among military trainees and recreational divers and to associate their occurrence with exposure and individual background factors such as age and comorbidity. We conducted a retrospective analysis on the medical records and diving parameters of all patients who were treated for IPE at the Hyperbaric Medicine Department of Sainte-Anne Military Hospital in Toulon, France, between January 2017 and August 2019. In total, 57 subjects were included in this study, with ages ranging from 20 to 62 years. These subjects were divided into two distinct groups based on exposure categories: (1) underwater/surface military training and (2) recreational scuba diving. The first group consisted of 14 individuals (25%) with a mean age of 26.5 ± 2.6 years; while, the second group comprised 43 individuals (75%) with a mean age of 51.2 ± 7.5 years. All divers under the age of 40 were military divers.

RESULTS

In 40% of cases, IPE occurred following intense physical exercise. However, this association was observed in only 26% of recreational divers, compared to 86% of military divers. Among civilian recreational divers, no cases of IPE were observed in subjects under the age of 40. The intensity of symptoms was similar between the two groups, but the duration of hospitalization was significantly longer for the recreational subjects.

CONCLUSION

It seems that the occurrence of IPE in young and healthy individuals requires their engagement in vigorous physical activity. Additionally, exposure to significant ventilatory constraints is a contributing factor, with the intensity of these conditions seemingly exclusive to military diving environments. In contrast, among civilian recreational divers, IPE tends to occur in subjects with an average age twice that of military divers. Moreover, these individuals exhibit more prominent comorbidity factors, and the average level of environmental stressors is comparatively lower.

Symptom Duration, Recurrence, and Long-Term Effects of Swimming-Induced Pulmonary Edema: A 30-Month Follow-Up Study

BACKGROUND

Swimming-induced pulmonary edema (SIPE) has been reported to subside within 24 to 48 h, but comprehensive follow-up studies on symptom duration and long-term effects are missing.

RESEARCH QUESTION

What are the symptom duration, recurrence, and long-term effects of SIPE?

STUDY DESIGN AND METHODS

A follow-up study was conducted, based on 165 cases of SIPE from Sweden's largest open-water swimming event with 26,125 individuals participating during 2017-2019. Data on patient characteristics, clinical findings, and symptoms were collected at admission. Telephone interviews at 10 days and 30 months were performed to explore symptom duration, recurrence of SIPE symptoms, need for medical evaluation, and long-term effects of self-assessed general health and physical activity level.

RESULTS

Follow-up at 10 days was performed for 132 cases and at 30 months for 152 cases. Most of the patients were women, and their mean age was 48 years. At the 10-day follow-up, symptom duration > 2 days after the swimming race was reported by 38%. The most common symptoms were dyspnea and cough. In patients at 30-month follow-up, recurrence of respiratory symptoms during open-water swimming was reported by 28%. In multivariable logistic regression, asthma was independently associated with both symptom duration > 2 days and recurrence of SIPE symptoms (P = .045 and P = .022, respectively). Most participants reported equal or improved general health (93%) and physical activity level (85%) after experiencing SIPE, but 58% had not swum in open water since the event.

INTERPRETATION

The present large cohort study challenges the established hallmark of SIPE symptom duration < 48 h, whereas SIPE recurrence was in the previously reported range. At 30 months, most patients reported unchanged self-assessed general health and physical activity level. These findings add to our understanding of the course of SIPE and can provide evidence-based information to swimmers and health care professionals.

Myocardial oedema in the setting of immersion pulmonary oedema - Cause or effect?

Immersion pulmonary oedema (IPE) is an under-reported and poorly understood phenomenon thought to be related to exercise-induced haemodynamic changes while submersed in water. Previous work has demonstrated reversible myocardial dysfunction during acute episodes. We present a case of IPE with concomitant, transient, left ventricular myocardial oedema characterised via MRI. This is a novel finding and may be evidence of left ventricular strain due to pressure overload or secondary to a subclinical myocarditis.

An Unusual Presentation of Pulmonary Edema During an Ice Dive at Altitude

Military diving operations occur in a wide range of austere environments, including high-altitude environments and cold weather environments; however, rarely do both conditions combine. Ice diving at altitude combines the physiologic risks of diving, a hypothermic environment, and a high-altitude environment all in one. Careful planning and consideration of the potential injuries and disease processes affiliated with the aforementioned physiologic risks must be considered. In this case report, we describe a Navy diver who became obtunded secondary to hypoxia during an ice dive at 2,987 m (9,800 ft) elevation and was subsequently diagnosed with high-altitude pulmonary edema. Further consideration of the environment, activities, and history does not make this a clear case, and swimming-induced pulmonary edema which physiologically possesses many overlaps with high-altitude pulmonary edema may have contributed or been the ultimate causal factor for the diver's acute response.

Case Series of Triathletes with Takotsubo Cardiomyopathy Presenting with Swimming-Induced Pulmonary Edema

Objectives

To report three cases of triathletes who presented with swimming-induced pulmonary edema (SIPE) following water immersion. They were subsequently diagnosed with Takotsubo cardiomyopathy (TCM).

Design

Retrospective case series.

Method

All cases were recreational athletes competing in mass participation triathlons between June 2018 and 2019. They were initially managed by the event medical team and subsequently at the local tertiary level hospital. Written consent was gained from all the subjects.

Results

The three triathletes were aged between 50 and 60 years, two were females, and all presented with acute dyspnoea on exiting the water. Two also presented with chest pain and haemoptysis. A diagnosis of SIPE was suspected by the medical event team on initial presentation of low oxygen saturations and clinical signs of pulmonary oedema. All were transferred to the local emergency department and had signs of pulmonary oedema on chest radiographs. Further investigations led to a diagnosis of TCM with findings of T wave inversion in anterolateral electrocardiogram leads and apical hypokinesia on transthoracic echocardiogram and unobstructed coronary arteries.

Conclusions

This case series presents triathletes diagnosed with SIPE and TCM following the open water swim phase. It is unclear whether the myocardial dysfunction contributed to causation of SIPE or was the result of SIPE. Mass participation race organizers must be prepared that both SIPE and TCM can present in this population. Those presenting with an episode of SIPE require prompt evaluation of their cardiac and pulmonary physiology. Further research is required to ascertain the exact nature of the relationship between TCM and SIPE.

An update on environment-induced pulmonary edema – “When the lungs leak under water and in thin air”

Acute pulmonary edema is a serious condition that may occur as a result of increased hydrostatic forces within the lung microvasculature or increased microvascular permeability. Heart failure or other cardiac or renal disease are common causes of cardiogenic pulmonary edema. However, pulmonary edema may even occur in young and healthy individuals when exposed to extreme environments, such as immersion in water or at high altitude. Immersion pulmonary edema (IPE) and high-altitude pulmonary edema (HAPE) share some morphological and clinical characteristics; however, their underlying mechanisms may be different. An emerging understanding of IPE indicates that an increase in pulmonary artery and capillary pressures caused by substantial redistribution of venous blood from the extremities to the chest, in combination with stimuli aggravating the effects of water immersion, such as exercise and cold temperature, play an important role, distinct from hypoxia-induced vasoconstriction in high altitude pulmonary edema. This review aims at a current perspective on both IPE and HAPE, providing a comparative view of clinical presentation and pathophysiology. A particular emphasis will be on recent advances in understanding of the pathophysiology and occurrence of IPE with a future perspective on remaining research needs.

Swimming-induced pulmonary edema with review of literature

Swimming-induced pulmonary edema (SIPE) is a rare form of non-cardiogenic pulmonary edema occurring in swimmers. It is important to consider the diagnosis of SIPE and differentiate it from aspiration pneumonitis in patients presenting with respiratory distress after swimming. We report a case of military recruit who developed SIPE. This is the first reported case of SIPE from India. Owing to the paucity of reported cases, the treatment of this entity in the literature is anecdotal, and we present successful management of SIPE with non-invasive ventilation and diuretics. A review of literature is made to understand the diagnosis, pathophysiology, and management of SIPE.

Research Progress on the Mechanism of Right Heart-Related Pulmonary Edema

Objective. To investigate the mechanisms underlying the development of right heart-associated PE. Background. Right heart-related pulmonary edema (PE) refers to PE resulting from impaired right heart function caused by primary or secondary factors, which is common in critically ill patients. Although the clinical manifestations of different types of right heart-related PE are similar, the pathophysiological changes and treatment methods are significantly different. According to the hemodynamic mechanism, right heart-related PE is primarily classified into two types. One is the increase of right heart flow, including extravascular compression, intravascular compression, cardiac compression, and cardiac decompression. The other type is the abnormal distribution of pulmonary circulation, including obstruction, resistance, pleural decompression, or negative pressure. With the development of hemodynamic monitoring, hemodynamic data not only help us understand the specific pathogenesis of right heart-related PE but also assist us in determining the direction of therapy and enabling individualized treatment. Summary. This article presents a review on right heart-associated PE, with a perspective of hemodynamic analysis, and emphasizes the importance of right heart function in the management of circulation. Understanding the mechanism of right heart-associated PE will not only aid in better monitoring right heart function but also help intensivists make a more accurate identification of various types of PE in the clinic.

Swimming-Induced Pulmonary Edema: Evaluation of Prehospital Treatment With CPAP or Positive Expiratory Pressure Device

BACKGROUND

Swimming-induced pulmonary edema (SIPE) occasionally occurs during swimming in cold open water. Although optimal treatment for SIPE is unknown, non-invasive positive pressure ventilation (NPPV) is an option for prehospital treatment.

RESEARCH QUESTION

Is NPPV a feasible and safe prehospital treatment for SIPE, and which outcome measures reflect recovery after treatment?

STUDY DESIGN AND METHODS

A prospective observational study was conducted at Vansbrosimningen, Sweden's largest open water swimming event, from 2017 through 2019. Swimmers with a diagnosis of SIPE and with peripheral oxygen saturation (Spo2) of ≤ 95%, persistent respiratory symptoms, or both were eligible for the study. NPPV was administered on site as CPAP by facial mask or as positive expiratory pressure (PEP) by a PEP device. Discharge criteria were Spo2 of > 95% and clinical recovery. Four outcome measures were evaluated: Spo2, crackles on pulmonary auscultation, pulmonary edema on lung ultrasound (LUS), and patient-reported respiratory symptoms.

RESULTS

Of 119 treated individuals, 94 received CPAP, 24 received treatment with a PEP device, and one required tracheal intubation. In total, 108 individuals (91%) were discharged after NPPV for a median of 10 to 20 min and 11 individuals (9%) required hospital transfer. NPPV resulted in increased Spo2 from a median of 91% to 97% (P < .0001) together with improvement of six patient-reported respiratory symptoms (median numerical rating scales, 1-7 to 0-1; P < .0001). No significant decrease in auscultation of crackles (93% vs 87%; P = .508) or pulmonary edema on LUS (100% vs 97%; P = .500) was seen during NPPV treatment.

INTERPRETATION

NPPV administered as CPAP or via a PEP device proved feasible and safe as prehospital treatment for SIPE with a vast majority of patients discharged on site. Spo2 and patient-reported respiratory symptoms reflected recovery after treatment, whereas pulmonary auscultation or LUS findings did not.

Latent Class Analysis of Decompression Sickness Symptoms of Women Divers

This study aimed to investigate the types of clinical manifestations of decompression sickness among women divers (haenyeos) in Jeju using latent class analysis and to identify factors related to the condition. A total of 527 haenyeos who received their certification in diving fishery from Jeju and were working from 15 March to 31 May 2021 were included in this study. According to the results of the study, the latent classes were classified into type 1, type 2, and mixed symptoms groups (Akaike information criterion (AIC) = 6587.29, Bayesian information criterion (BIC) = 6698.23, sample size-adjusted BIC (saBIC) = 6615.70). For personal characteristics, age (χ2 = 40.31, p < 0.001) and education level (χ2 = 28.15, p < 0.001) showed a significant difference by latent class type. For work-related characteristics, diving experience (χ2 = 29.99, p < 0.001) and break time (χ2 = 9.32, p = 0.011) showed a significant difference by latent class type. The health-related characteristics, menopausal period (χ2 = 40.10, p < 0.001), body mass index (χ2 = 14.80, p = 0.013), and fatigue level (χ2 = 58.23, p < 0.001), showed a significant difference by latent class type. Rather than approaching the management of work-related diseases simply from the work environment perspective, it is important to increase the availability of health professionals who are capable of continuous health monitoring and management of women divers in their workplace.

[Sudden-onset dyspnea, cough and hemoptysis in a previously healthy 46-year-old female swimmer]

This case report describes the case of a patient that developed suddenly dyspnea, cough and hemoptysis while swimming. Under the clinical presentation of pulmonary edema she required short-term invasive ventilation. Initially, echocardiography showed globally highly reduced systolic left ventricular function, which rapidly normalized. After exclusion of other pulmonary or cardiac causes swimming-induced pulmonary edema was diagnosed. This should be considered in cases of pulmonary edema, particularly in patients practicing sports with contact to water.

Immersion pulmonary oedema in a triathlete - a diagnostic challenge in sports cardiology

Immersion pulmonary oedema, also referred to as swimming-induced pulmonary oedema, is a form of pulmonary oedema which usually occurs during swimming in cold water. The condition is most common in triathlon athletes; it was first reported in military divers. The main symptoms include acute dyspnoea, cough, and occasionally haemoptysis, which usually subside within approximately 48 hours. The pathomechanism is not fully understood, but oedema is suspected to be due to an increased systemic vascular resistance that overloads the left ventricle. The diagnostic process can be challenging and require multiple stages to rule out a number of other possible conditions. In view of the circumstances in which incidents typically occur, immersion pulmonary oedema poses an immediate life threat to individuals involved in selected forms of physical activity, where survival is often determined by appropriate training of medical services.

Incidence of Swimming-Induced Pulmonary Edema: A Cohort Study Based on 47,600 Open-Water Swimming Distances

Background

Despite increasing awareness of swimming-induced pulmonary edema (SIPE), large population-based studies are lacking and the incidence is unknown.

Research Question

What is the incidence of SIPE in a mixed group of competitive and recreational swimmers during a large open-water swimming event?

Methods

In four consecutive years (2016-2019), a prospective cohort study was conducted during Sweden’s largest open-water swimming event, Vansbrosimningen. All swimmers seeking medical care with acute respiratory symptoms were eligible for the study. SIPE diagnosis was based on clinical findings in 2016 and 2017 and pulmonary edema assessed by lung ultrasound in 2018 and 2019. Data on patient characteristics, clinical findings, and information about the race were collected.

Results

Based on 47,573 consecutive swimming distances, 322 patients with acute respiratory symptoms (0.68%; CI, 0.61%-0.75%) were treated at the mobile medical unit. Of these, 211 patients (0.44%; CI, 0.39%-0.51%) received a diagnosis of SIPE. The annual incidence of SIPE was 0.34%, 0.47%, 0.41%, and 0.57%, respectively, from 2016 through 2019. Most patients diagnosed with SIPE were women (90%), despite about equal percentages of men and women participating (47% men and 53% women). The incidence of SIPE overall was 0.75% in women and 0.09% in men. The incidence increased with age, from 0.08% in the youngest age group (18-30 years) to 1.1% in the oldest age group (≥ 61 years). Based on multiple logistic regression analysis, the adjusted odds for SIPE occurring was 8.59 times higher for women compared with men and 12.74 times higher for the oldest age group compared with the youngest age group.

Interpretation

The incidence of SIPE over 4 years during a large open-water swimming event in Sweden was 0.44%. The incidence was higher in women than in men and increased with age.

Breath-Hold Diving - The Physiology of Diving Deep and Returning

Breath-hold diving involves highly integrative physiology and extreme responses to both exercise and asphyxia during progressive elevations in hydrostatic pressure. With astonishing depth records exceeding 100 m, and up to 214 m on a single breath, the human capacity for deep breath-hold diving continues to refute expectations. The physiological challenges and responses occurring during a deep dive highlight the coordinated interplay of oxygen conservation, exercise economy, and hyperbaric management. In this review, the physiology of deep diving is portrayed as it occurs across the phases of a dive: the first 20 m; passive descent; maximal depth; ascent; last 10 m, and surfacing. The acute risks of diving (i.e., pulmonary barotrauma, nitrogen narcosis, and decompression sickness) and the potential long-term medical consequences to breath-hold diving are summarized, and an emphasis on future areas of research of this unique field of physiological adaptation are provided.

Incidence and Impact of Swimming-Induced Pulmonary Edema on Navy SEAL Candidates

BACKGROUND

Respiratory complications such as swimming-induced pulmonary edema (SIPE) are a common feature of United States Navy Special Warfare (NSW) training.

RESEARCH QUESTION

This study was designed to evaluate the incidence and clinical features of SIPE seen in this population.

STUDY DESIGN AND METHODS

A prospective, observational review of all NSW candidates over a 15-month period was designed. Baseline height, weight, and ECG data were obtained. Candidates with respiratory issues were evaluated with a two-view chest radiograph and ECG while symptomatic and were closely followed up. The chest radiograph and clinical data were then independently reviewed.

RESULTS

A total of 2,117 NSW candidates participated in training during the study period, with 106 cases of SIPE identified (5.0%). Ten additional cases of SIPE were repeat episodes in candidates already diagnosed. Forty-four cases of pneumonia were identified (no repeat cases). The majority had cough (90.4%), frothy-pink sputum (35.6%), and hemoptysis (23.7%). Overall, 80.1% of candidates had an oxygen saturation ≥ 90%. Physical examination findings were variable: crackles (50%), wheezing (36%), and rhonchi (19%). Several had more than one feature; 23% presented with a normal examination. Radiologic findings in patients with SIPE most commonly revealed an interstitial pattern with perifissural thickening, larger average azygos vein diameter, larger average heart size, and normal lung height. ECG findings were not significantly different from baseline. Height and weight were not significantly different between the groups. Lower water temperatures were suggestive of increased SIPE incidence, but this was not a statistically significant trend.

INTERPRETATION

The burden of SIPE in NSW training was greater than anticipated. Clinical symptoms and physical examination assisted by imaging were able to differentiate SIPE from pneumonia. ECG was not a useful diagnostic or screening tool, and height and weight did not affect risk of SIPE.

TRIAL REGISTRY

Institutional Review Board registration at Naval Medical Center, San Diego, California; Registration No.: NMCSD.2017.0020.

Lung function and oxygen saturation after participation in Norseman Xtreme Triathlon

OBJECTIVES

To examine evidence of exercise-induced bronchoconstriction (EIB) defined as ≥10% reduction in forced expiratory volume in one second (FEV₁ ) and exercise-induced arterial hypoxemia (EIAH) defined as ≥4% reduction in oxygen saturation (SpO₂ ) from before to after participation in the Norseman Xtreme Triathlon. Secondarily, to assess whether changes in FEV₁ and SpO₂ are related to respiratory symptoms, training volume, and race time.

METHODS

In this quasi-experimental non-controlled study, we included 63 triathletes (50♂/13♀) aged 40.3 (±9.0) years (mean ± SD). Fifty-seven (46♂/11♀) measured lung function and 54 (44♂/10♀) measured SpO₂ before the race, 8-10 minutes after the race (post-test 1) and the day after the race (post-test 2). Respiratory symptoms and training volume were recorded with modified AQUA questionnaire. ANOVA for repeated measures was used to detect differences in lung function and SpO₂ . Statistical significance was accepted at 0.05 level.

RESULTS

Twenty-six participants (46%) presented with EIB at post-test 1 and 16 (28%) at post-test 2. Lung function variables were significantly reduced from baseline to post-test 1 and 2. Thirty-five participants (65%) showed evidence of mild to moderate EIAH. No significant correlations were observed except a weak correlation between maximal reduction in FEV₁ and respiratory symptoms (r = 0.35, P = .016).

CONCLUSION

Our results demonstrated that 46% of the participants presented with EIB and 65% showed evidence of EIAH after the Norseman Xtreme Triathlon. Changes in FEV₁ and SpO₂ were not correlated to weekly training hours or race time. We observed a weak correlation between maximal reduction in FEV₁ and respiratory symptoms.

Snorkeling Induced Pulmonary Edema: A Case Report and Review of the Literature

Swimming-induced pulmonary edema (SIPE), also called immersion pulmonary edema (IPE), is a medical condition seen in various water-based activities such as scuba diving, swimming, aqua jogging, triathlete competition and snorkeling. It occurs when transcapillary filtration of low protein fluid collects in the lungs, in the absence of water aspiration during an aquatic activity, causing acute dyspnea, cough and/or hemoptysis. The hallmark of this entity is the complete resolution of symptoms within 48 hours. SIPE in snorkeling is an under-reported and understudied subject. The true prevalence of SIPE is unknown with an estimated range from 1.8-60% among combat swimmers trainee and 1.4% in triathletes. Recent developments have been done in elucidating the pathophysiology of SIPE with regards to pulmonary capillary pressure so that the predisposing factors and potential causes can be targeted. SIPE can be a potentially life-threatening condition, which needs to be recognized by the swimmers, divers, supervising physicians in order to diagnose and manage it promptly. We report a rare case of SIPE in snorkeling which presented with acute respiratory symptoms and managed with supportive measures in the hospital.

Complete upper airway collapse and apnoea during tethered swimming in horses

BACKGROUND

There is limited knowledge of the breathing strategy and impact on the patency of the upper respiratory tract (URT) in swimming horses.

OBJECTIVES

To describe the respiratory responses and endoscopic appearance of the URT during tethered swimming in horses.

STUDY DESIGN

Prospective descriptive study.

METHODS

Ten race-fit horses, with no history of URT obstruction, were examined during tethered swimming. Endoscopic examination, heart rate, sound recordings and above and below water video recordings were obtained. Plasma lactate concentration was measured before and 5 min after swimming and tracheal endoscopy was performed 30 min after exercise to assess for presence of blood or mucus. Four horses also underwent endoscopy during exercise on the track.

RESULTS

Mean (±s.d.) breathing frequency was 28 ± 5 breaths/min during swimming, with a brief inspiration (mean ± s.d. T_I  = 0.51 ± 0.08 s), followed by a period of apnoea (1.59 ± 0.53 s) and then a short, forced expiration (T_E  = 0.42 ± 0.5 s). During apnoea all horses exhibited complete collapse of the URT including closure of the external nares, nasopharynx and rima glottidis (with bilateral adduction of the arytenoid cartilages and vocal folds) and, in two horses, epiglottic retroversion. No horses had URT collapse during overground exercise. Locomotor-respiratory coupling was not observed during swimming. Median (IQR) plasma lactate post swim was 4.71 mmol/L (2.08-8.09 mmol/L) vs 0.68 mmol/L (0.65-0.71 mmol/L) preswim. Post swim endoscopy revealed grade 1 exercise-induced pulmonary haemorrhage (EIPH) in 2 horses. Median mucus grade was 1 (range 0-3).

MAIN LIMITATIONS

Overground endoscopy was not performed in all horses.

CONCLUSIONS

Horses experienced complete URT collapse associated with post inspiratory apnoea when swimming. The reason for this is unknown but may be to aid buoyancy or associated with the mammalian dive response - a survival reflex to preserve oxygen stores and prevent water entering the lungs.

Late-Presenting Swimming-Induced Pulmonary Edema: A Case Report Series from the Norseman Xtreme Triathlon

Swimming-induced pulmonary edema (SIPE) may develop during strenuous physical exertion in water. This case series reports on three cases of suspected late-presenting SIPE during the Norseman Xtreme Triathlon. A 30-year-old male professional (PRO) triathlete, a 40-year-old female AGE GROUP triathlete and a 34-year-old male AGE GROUP triathlete presented with shortness of breath, chest tightness and coughing up pink sputum during the last part of the bike phase. All three athletes reported an improvement in breathing during the first major uphill of the bike phase and increasing symptoms during the downhill. The PRO athlete had a thoracic computed tomography, and the scan showed bilateral ground glass opacity in the peripheral lungs. The male AGE GROUP athlete had a normal chest x-ray. Both athletes were admitted for further observation and discharged from hospital the following day, with complete regression of symptoms. The female athlete recovered quickly following pre-hospital oxygen treatment. Non-cardiogenic pulmonary edema associated with endurance sports is rare but potentially very dangerous. Knowledge and awareness of possible risk factors and symptoms are essential, and the results presented in this report emphasize the importance of being aware of the possible delayed development of symptoms. To determine the presence of pulmonary edema elicited by strenuous exercise, equipment for measuring oxygen saturation should be available for the medical staff on site.

Evaluation of the Heart Function of Swimmers Subjected to Exhaustive Repetitive Endurance Efforts During a 500-km Relay

Aim: Knowledge of the human body's ability to adapt to repeated endurance efforts during swimming is limited. We echocardiographically assessed the impact of an exhausting and repetitive swimming effort on cardiac activity. Materials: Fourteen well-trained amateur swimmers (8 female swimmers aged 16-43 years and 6 male swimmers aged 13-67 years old) participated in an ultramarathon relay. Over 5 days, swimmers swam 500 km in the Warta River (in 5-km intervals). Each swimmer swam seven intervals, each within 44:46 to 60:02 min. Objective difficulties included low water temperatures, strong winds, rain, and night conditions. Methods: Transthoracic echocardiography (TTE) was performed three times: at baseline (the day before exertion), at peak effort, and during recovery (48 h after the event). The heart rate (HR) of each swimmer was monitored. Results: Swimmers completed the ultramarathon relay within approximately 91 h. The average HR value at the end of each interval was 91% HRmax. TTE test results showed no significant changes indicative of deterioration of myocardial function at peak effort or after 48 h. Significant increases in left ventricular (LV) ejection fraction, LV fractional shortening (LVFS), LV myocardial systolic velocity, and right ventricular (RV) fractional area changes observed on day 2 after swimming were compared to baseline values and peak effort values. No significant changes in diastolic heart function were observed. Conclusion: Echocardiography assessment indicated that prolonged intense swimming does not affect LV or RV function. Supercompensation of the post-event RV function and increased global LV systolic function demonstrated ventricular interaction after prolonged intense swimming.

Sudden Unexpected Death and the Mammalian Dive Response: Catastrophic Failure of a Complex Tightly Coupled System

In tightly coupled complex systems, when two or more factors or events interact in unanticipated ways, catastrophic failures of high-risk technical systems happen rarely, but quickly. Safety features are commonly built into complex systems to avoid disasters but are often part of the problem. The human body may be considered as a complex tightly coupled system at risk of rare catastrophic failure (sudden unexpected death, SUD) when certain factors or events interact. The mammalian dive response (MDR) is a built-in safety feature of the body that normally conserves oxygen during acute hypoxia. Activation of the MDR is the final pathway to sudden cardiac (SCD) in some cases of sudden infant death syndrome (SIDS), sudden unexpected death in epilepsy (SUDEP), and sudden cardiac death in water (SCDIW, fatal drowning). There is no single cause in any of these death scenarios, but an array of, unanticipated, often unknown, factors or events that activate or interact with the mammalian dive reflex. In any particular case, the relevant risk factors or events might include a combination of genetic, developmental, metabolic, disease, environmental, or operational influences. Determination of a single cause in any of these death scenarios is unlikely. The common thread among these seemingly different death scenarios is activation of the mammalian dive response. The human body is a complex tightly coupled system at risk of rare catastrophic failure when that "safety feature" is activated.

The breathless swimmer: could this be swimming-induced pulmonary edema?

Swimming-induced pulmonary edema is an infrequently encountered cause of acute respiratory distress in open-water swimmers. The condition can be challenging, with athletes often wanting answers to three main questions regarding (i) a definitive and robust diagnosis, (ii) the risk of recurrence, and (iii) what can be done to avoid recurrence. This commentary provides an overview of the best available evidence, in light of a recently published systematic review.

Troponins in scuba divers with immersion pulmonary edema

Immersion pulmonary edema (IPE) is a serious complication of water immersion during scuba diving. Myocardial ischemia can occur during IPE that worsens outcome. Because myocardial injury impacts the therapeutic management, we aim to evaluate the profile of cardiac markers (creatine phosphokinase (CPK), brain natriuretic peptide (BNP), highly sensitive troponin T (TnT-hs) and ultrasensitive troponin I (TnI-us) of divers with IPE. Twelve male scuba divers admitted for suspected IPE were included. The collection of blood samples was performed at hospital entrance (T0) and 6 h later (T0 + 6 h). Diagnosis was confirmed by echocardiography or computed-tomography scan. Mean ± S.D. BNP (pg/ml) was 348 ± 324 at T0 and 223 ± 177 at T0 + 6 h (P<0.01), while mean CPK (international units (IUs)), and mean TnT-hs (pg/ml) increased in the same times 238 ± 200 compared with 545 ± 39, (P=0.008) and 128 ± 42 compared with 269 ± 210, (P=0.01), respectively; no significant change was observed concerning TnI-us (pg/ml): 110 ± 34 compared with 330 ± 77, P=0.12. At T0 + 6 h, three patients had high TnI-us, while six patients had high TnT-hs. Mean CPK was correlated with TnT-hs but not with TnI-us. Coronary angiographies were normal. The increase in TnT during IPE may be secondary to the release of troponin from non-cardiac origin. The measurement of TnI in place of TnT permits in some cases to avoid additional examinations, especially unnecessary invasive investigations.

Occurrence, Risk Factors, Prognosis and Prevention of Swimming-Induced Pulmonary Oedema: a Systematic Review

Background

Swimming-induced pulmonary oedema (SIPE) can affect people with no underlying health problems, but may be life threatening and is poorly understood. The aim of this systematic review was to synthesise the evidence on SIPE incidence, prevalence, risk factors, short- and long-term outcomes, recurrence and effectiveness of interventions to prevent recurrences.

Methods

We carried out a literature search using bibliographic databases and reference lists. Risk of bias was assessed by adapting existing quality assessment tools including those developed by the National Heart Lung and Blood Institute.

Results

Nine studies met the inclusion criteria. Quantitative synthesis was not possible because of study heterogeneity. Five studies, which differed from each other in case definition, swimming environment, population characteristics and denominators, reported an incidence of 0.01% of UK triathlons raced over 5 years in unspecified swimming environments (one study, not fully reported, of men and women of unspecified age); 0.5% of river races swum over 3 days in Sweden (one study, of men and women up to the age of 70); and 1.8–26.7% of time trials in the sea around Israel (three studies of male teenage military trainees). One study reported that 1.4% of triathletes in the USA had experienced SIPE. One study found that hypertension, female sex, fish oil use, long course distance and another lower initial lung volumes and flows were risk factors for SIPE. A third study reported that higher mean pulmonary artery pressures and pulmonary artery wedge pressures, and lower tidal volumes were associated with SIPE. Three studies suggested that SIPE symptoms usually resolve within 24 h, although a restrictive deficit in lung function persisted for a week in one small study. We found no studies that reported deaths from SIPE. The single small study of longer-term outcomes reported no difference between affected and unaffected swimmers. Two studies suggested that around 30% of people report recurrences of SIPE. Two very small uncontrolled studies of the effect of sildenafil for recurrence prevention were inconclusive.

Conclusions

SIPE may be an important public health problem affecting the growing number of recreational open water swimmers. Further research should clarify the frequency of SIPE among recreational open water swimmers, confirm reported risk factors and explore others, explore long-term consequences and test interventions to prevent recurrences.

Electronic supplementary material

The online version of this article (10.1186/s40798-018-0158-8) contains supplementary material, which is available to authorized users.

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