An Open Water Swim Safety Idea

SwimBalloon

 

 

 

As I mentioned in my last blog post, I recently visited in Tokyo with the Japan Triathlon Union about the issue of athlete safety.  I had the chance to speak (albeit with translation!) with the race directors from many of Japan’s major triathlon races.

Dr. Masakazu Kawai, from the Yamagata prefecture, had a novel idea about swim safety to share with the group.

But first, to set the stage….

We know that being able to rescue a swimmer in distress in one of the most important aspects of an effective safety plan for a triathlon or stand-alone open water swim.  Fortunately, in most cases, the on-water lifesaving team is able to spot swimmers in distress who might be struggling to swim, or wave, or even simply yell that they need help.

For the lifeless swimmer–the victim of drowning, near drowning, or cardiac arrest–identification of the victim can be much more challenging.  And yet identification of the victim, prompt rescue from the water, and provision of CPR and use of the AED, if needed, is the chain of action that must be accomplished in just a very few minutes in order to avoid a fatality.  This chain all begins with identifying the victim.

In a crowd of swimmers, oftentimes all wearing black wetsuits, it can be hard to spot the single athlete who has gone lifeless and who is floating, but no longer swimming.  From afar, it can be difficult to tell whose arms are whose and it can be difficult to tell if a head is rotating to take a breath.

This is where Dr. Kawai’s idea might be helpful.  He suggests the use of a small, inflated, brightly-colored balloon that would be attached to each swimmer’s swim cap.  As the athlete is swimming, the balloon would bob left and right, with each turn of the head.  If an athlete goes lifeless, the balloon would simply sit still on the top of the water.  In a group of swimmers, then, there would be a very visible clue to a single lifeless swimmer–the single balloon that was no longer bobbing.  This might be visible even from a considerable distance and allow early, perhaps immediate, recognition of the lifeless swimmer.

Watch a short video clip that shows the idea and let me know what you think.  I’ll pass along any feedback to Dr. Kawai.  He’s also looking for event organizers to trial his idea.  We need simple, creative ideas like this.

Kawai

 

 

 

 

 

 

 

Related Posts:

  1. Some Great New Videos from WTC SwimSmart Initiative
  2. Swim Safe in 2014
  3. Triathlon Safety Initiatives

Japan and Triathlon Fatalities

TokyoShrineTower

 

 

 

 

 

 

I’ve recently returned from a trip to Tokyo, Japan, where I was the guest of the Japan Triathlon Union (JTU).  The occasion was their organization’s 5th Annual Forum, which this year was devoted to the issue of triathlon race safety.

I appreciate the kind invitation from Mr. Otsuka and Mr. Nakayama, the help of JTU’s Kenta Kodama with the travel arrangements, and the tremendous help with translation from Ms. Tomoko Wada.  My hosts were gracious in every way.  I must also thank the kind folks at USA Triathlon (USAT)–Terri Waters and Kathy Matejka, for help with gathering some updated information to present in Japan, and USAT President Barry Siff for making the necessary connections with JTU.

As readers here will know, I’ve had an interest in triathlon-related fatalities and the broader issue of sudden cardiac death among endurance athletes.  I had the opportunity to lead a recent USAT effort to learn more about triathlon-related fatalities and our work resulted in a 2012 report entitled “Fatality Incidents Study.” As I’ve said before, this report is good reading for athletes and event organizers who are looking for recommendations about how to race safely and conduct events with athlete safety as a first priority.

Sadly, there were 6 triathlon-related fatalities in Japan in 2015, the most ever in a single year there.  Dr. Ryoji Kasanami, the Chairman of the JTU’s Medical Committee, had become familiar with our work here in the USA and was interested in learning how our findings might help JTU with better safety planning, on the parts of both athletes and event organizers.

I gave a talk at the Forum where I outlined the USAT experience with fatalities since 2003.  In large part, the information is summarized in my previous blog post, Triathlon Fatalities: 2013 in review.  I was able to include some updates through the 2015 season, but the central themes were the same now as then:

  • There is variation in the fatality rate from year to year, with an overall fatality rate of ~1 per 70,000 participants
  • Most fatalities occur during the swim portion of events
  • Most victims are male
  • Fatalities are most common among middle-aged athletes
  • There have been no fatalities among elite (professional) athletes
  • Among victims, there is a wide range in athlete experience and ability
  • There is a small number of trauma-related fatalities, arising from bicycle crashes
  • Among non-traumatic fatalities, the vast majority suffered cardiac arrest at the race venue
  • Available autopsy information for non-traumatic fatalities has shown heart abnormalities in the majority

Dr. Kevin Harris, from the Minneapolis Heart Institute, and I will be presenting an abstract at the upcoming American College of Cardiology meeting in April in Chicago on this topic.  We’ll be sharing consolidated information about 106 fatalities, including the autopsy findings from 41 of the non-traumatic fatalities.  I’ll report back here at the blog with an update in April.

Dr. Kasanami shared information about the Japanese experience with 37 fatalities over the past 3 decades.  There were many similarities to the experience in the USA:

  • Some years were “safer” than others
  • Most fatalities occurred during the swim portion of events
  • Most victims were male
  • Fatalities were most common among middle-aged athletes
  • There have been no fatalities among elite athletes
  • There were no fatalities in young athletes

There were also some notable differences:

  • There were no fatalities during the bike portion
  • Autopsy was seldom performed in the victims

Interestingly, the bike course is always closed to vehicular traffic during triathlons in Japan, and this might obviously have an impact on the number of crashes and trauma-related fatalities.  One interesting anecdote shared by a pathologist attendee related to the finding of inner ear bleeding (hemorrhage) in 2 victims.  I’m not sure about the significance of this observation.

I’m intrigued by the many similarities of the Japanese experience with race-related fatalities.  I also know from preliminary discussions with officials at Triathlon Australia that the experience in Australia is similar as well.  I suspect that the causes of cardiac arrest in participating athletes are common broadly, and are more dependent on simply the human condition rather than race-related factors that might be specific to one region or another (eg, race safety or technical rules, approach to medical care on site, warm-up, etc.).

I’ll mention here that the Medical Committee of the International Triathlon Union (ITU) is very interested in this issue, particularly as it relates to elite athletes.  I understand that efforts are being made to implement the requirement for mandatory periodic health evaluations, including EKG screening, for youth, U23, and elite athletes who participate in ITU races, perhaps beginning in the 2017 season.  This follows on the heels of the international rowing federation adopting a similar policy, gradually, during the 2014 and 2015 seasons.

I worry a little about the ITU focus on elite athletes, since the problem of race-related fatalities seems to be largely one of age-group athletes, but I hope that age-group athletes will be paying attention to any recommendations that are implemented.

Lastly, I’ll close with some photographs from the trip.  Since this was my first-ever visit to Tokyo and Japan, my hosts graciously afforded me about 8 hours of free time one day for the purpose of sightseeing and I took advantage.  I hope to return to Japan soon to see even more.

TokyoFishMarketTokyoSkyline


 

 

 

 

 

 

ImperialPalace

 

 

 

 

Related Posts:

  1. Triathlon Fatalities: 2013 in Review
  2. Fatal Arrhythmias in Open Water Swimming: What’s the Mechanism?
  3. Triathlon-Related Deaths: The Facts and What You Should Know

 

Triathlon, Open Water Swimming, and the Heart: What Can We Learn From Dolphins and Seals?

dolphin

 

 

 

 

 

 

A recent study about marine mammals caught my eye.  I don’t know much about non-human biology and physiology, but this study on dolphins and seals may shed some light on the problem of fatalities during open water swimming or triathlon events.

The Study

A group of investigators headed by Terrie Williams from the University of California at Santa Cruz shared their report, “Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals” in the January 16th edition of Nature Communications (1).

This group of investigators has been interested in the physiology of the so-called “dive response” in marine mammals.  This is a response that is governed by the involuntary, or autonomic, nervous system, which has two antagonistic components:  the parasympathetic nervous system and the sympathetic nervous system.  As a group, the marine mammals depend on feeding by chasing pray to depths that can range up to 3,000 m.  Even at lesser depths, these mammals must maintain a breath-hold under large hydrostatic pressures while they undergo extreme exertion to catch their pray.  During a dive, breath-holding stimulates the parasympathetic nervous system to slow the heart rate (producing bradycardia).  At the same time, the exertion required to chase pray stimulates the sympathetic nervous system, producing an increase in the heart rate.  The current study offers the first detailed study of the interplay between the components of the autonomic nervous system during routine diving and feeding activity in these animals.

The investigators created an electrocardiograph-accelerometer depth monitor that was deployed on 10 Atlantic bottle-nosed dolphins and 3 Weddell seals.  This device allowed high-fidelity recording of the heart rate, ECG, water depth, and swimming stroke frequency (a measure of exertion) during dives.  For the dolphins, measurements were made for 74 dives to depths of up to 210 m.  For the seals, measurements were made for 91 dives to depths of up to 390 m.

The Results

As expected, there was a strong relationship between diving depth and heart rate for both species, with heart rates falling during descent and reaching a minimum at the lowest depth of the dive.  Superimposed on this effect was an additional effect of exertion.  For the dolphins, the maximum heart rate was 1.7 to 3.7 times greater during periods of extreme exercise compared to gliding alone.  For the seals, the maximum heart rate was 1.5 to 1.8 times greater during periods of extreme exercise compared to gliding alone.

The surprising finding was that cardiac arrhythmias occurred in more than 73% of the dives.  The investigators defined arrhythmias to include ectopic beats or significantly increased variability in the interbeat interval (IBI).  There were apparently no sustained or fatal arrhythmias., but there were discrete examples of “wandering pacemaker” and ventricular premature beats.  In the Weddell seals, there were often patterns of alternating periods of tachycardia (fast heart rate) and bradycardia (low heart rate) during periods of constant, intense exertion.

The presence of cardiac arrhythmias was strongly correlated with increased depth of dive (parasympathetic activation) and increased exertion (sympathetic activation).  As an example, cardiac arrhythmias occurred in 81% of the dolphin dives to >210 m but in only 26% of dives to <100 m.

The authors concluded that our previous understanding of the dive reflex in marine mammals was not totally correct.  Given that these animals depend on diving for their food sources, the development of cardiac arrhythmias during feeding appears to be mal-adaptive.  In fact, feeding might actually be dangerous.

My Thoughts

At first glance, the physiology of the diving response of dolphins and seals during feeding seems far afield from open water swimming and triathlon.  And moreover, we already know about the development of cardiac arrhythmias during submersion in breath-holding humans as well as other marine species.  The important observation here, though, is what I might call “irritability” or “instability” in the heart rhythm during periods of intense parasympathetic and intense sympathetic activation….and that’s the possible link to human fatalities during open water swimming or triathlon.

We know from autopsy reports of triathletes who’ve died during the swim portion of an event that there are sometimes only subtle abnormalities of the heart, and often nothing that seems explanatory.  That leaves us in a difficult position to explain such deaths.  In a previous blog post, I wrote about one very plausible hypothesis. Two UK physiologist,s X and X, proposed the concept of “autonomic conflict,” where a surge in both the parasympathetic and sympathetic stimulation of the heart might lead to a fatal arrhythmia.  I’ve been intrigued with this hypothesis because it seems to fit many of the observations made about the swim victims.  It is easy to see where exertion, cold water, anxiety, etc. might lead to strong sympathetic activation.  And it’s equally easy to see where facial wetting, water entering the mouth/hypopharynx/nasopharynx, and breath-holding, even without diving, might lead to strong parasympathetic activation.  In that instant, in an athlete with some sort of susceptible heart, a fatal arrhythmia might occur.

The new observations about the dolphins and seals seem to play into this hypothesis.

 

Related Posts:

1. Fatalities in Open Water Swimming:  What’s the Mechanism?

2. Triathlon Fatalities:  2013 in Review

 

Reference:

1.  Williams TM, Fuirman LA, Kendall T, et al.  Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals.  Nature Communications 2015;6:6055.

 

 

 

In the News: Cardiac Screening for Adult Recreational Athletes

Swiss flag

 

 

 

 

An important new study caught my eye.  In last week’s British Journal of Sports Medicine, Andrea Menafoglio and her colleagues from Bellinzona, Switzerland published (epublished ahead of print) a report entitled, “Cardiovascular evaluation of middle-aged individuals engaged in high-intensity sport activities:  implications for workload, yield and economic costs.”(1)

The study is important because it addresses the issue of cardiovascular screening in adult, recreational athletes, an area that’s received very little attention.

By comparison, the issue of cardiac screening for young, competitive athletes has received a great deal of attention over the past 25 years.  Many prominent medical scientific organizations have issued recommendations for pre-participation screening in young athletes, including the American Heart Association (1), American College of Cardiology (ACC), American Academy of Family Practice (AAFP), American Academy of Pediatrics (AAP), American College of Sports Medicine (ACSM), American Medical Society for Sports Medicine (AMSSM), just to name some of the American organizations.

These recommendations form the basis for the widespread use of mandatory pre-participation screening in secondary schools and colleges. The goal of such screening programs is to reduce the number of fatalities from sudden cardiac problems that arise during sporting activities.   The successes and pitfalls of such screening programs have been reported and the findings have engendered lively debate about what elements to include in screening programs, their effectiveness, and justification of their cost.

In this new study, the investigators report on a “real world” glimpse into cardiovascular screening in adult, recreational athletes.  Their aims were to evaluate the practicality of such a screening program, to measure the prevalence of previously unrecognized cardiovascular conditions in this group, and to determine the costs associated with initial screening and follow-up evaluation of athletes with an abnormal initial evaluation.

 

The Study

The investigators enrolled 785 athletes, aged 35-65 years (mean, 46.8 years), who engaged in “high-intensity sports” for at least 2 hours per week.  The athletes’ sports included running (in 33%) and cycling (in 24%), among others.  The majority of subjects (73%) were male.  The athletes were primarily “amateur” (69.7), but the group included some who competed in regional (23.7%), national (4.6%), or international competition (2.0%).

Athletes with a known history of cardiovascular disease, except for treated high blood pressure, as well as athletes who had previously undergone cardiac screening within the previous year were excluded.

Each athlete underwent a cardiac screening evaluation according to the current guidelines established by the European Association of Cardiovascular Prevention and Rehabilitation (EACPR).  The evaluation was free to each athlete and included:

  • Thorough personal and family medical history
  • Physical examination
  • ECG
  • Estimation of the individual’s cardiovascular risk using the Systemic Coronary Risk Evaluation (SCORE) chart for Switzerland
  • Blood testing for total cholesterol and serum glucose.

The SCORE chart was used to estimate the athlete’s 10-year risk of death due to atherosclerotic heart disease based on gender, age, total cholesterol level, systolic blood pressure, and smoking status.  Athletes were deemed at “high risk” if their predicted risk was >5% or if any single risk factor (eg, total cholesterol, blood pressure) was markedly abnormal.  The cost of this screening evaluation was reported to be $130 per athlete, or $102,050 total.

 

The Findings

The screening evaluation was abnormal in 112 athletes (14.3% of the total):

  • 5.1% due to abnormal, “pathologic” ECG findings
  • 4.7% because of abnormal physical examination
  • 1.6% due to a “positive” personal or family medical history
  • 4.1% because an athlete was at “high risk” for atherosclerotic heart disease

Each of these athletes then underwent subsequent, more detailed testing to shed more light on the athlete’s cardiac circumstance and to determine if a true cardiac problem was present.  These tests included, among others:  echocardiogram (an ultrasound examination of the heart’s structure and function); stress test; 24-hour blood pressure monitoring; 24-hour Holter monitoring (of the ECG, continuously, to evaluate for arrhythmias); cardiac MRI; coronary angiography; and tilt testing.  A total of 194 such tests were performed and these additional tests had a total cost of $54,556.

In the end, a new, previously unsuspected cardiovascular problem was identified in 22 (or 2.8% of the 785) athletes:

  • 8 with hypertension
  • 5 with mitral valve prolapse and at least moderate mitral regurgitation
  • 3 with biscuspid aortic valve (2 with moderate aortic regurgitation and 1 with mild aortic stenosis)
  • 1 with mild pulmonary valve stenosis
  • 1 with vaso-vagal syncope
  • 1 with Wolf-Parkinson-White syndrome
  • 1 with hypertrophic cardiomyopathy (HCM)*
  • 1 with significant coronary artery disease and “old” myocardial infarction*
  • 1 with abdominal aortic aneurysm*

This group included 19 men and 3 women.  Of these 22 athletes with newly diagnosed cardiac conditions, 3 were deemed ineligible to participate in their sports because of unacceptably high risk of cardiovascular events (indicated by an asterisk, above).  Each of the 3 athletes who were deemed ineligible for sports activities were identified by an abnormal ECG during the initial screening.

The other 90 athletes with an abnormal initial screening evaluation were “cleared” on the basis of their subsequent testing.  We might refer to these athletes as the “false-positives”–those with an abnormal initial screening evaluation, but no real cardiovascular problem.

Interestingly, no diagnosis of coronary artery disease (CAD) resulted from the 76 exercise stress tests that were performed.

 

The Investigators’ Conclusions

The authors reached 4 main conclusions:

  1. The screening program was effective in identifying a small, but significant, number of athletes with significant cardiovascular conditions that required treatment or monitoring.
  2. The screening program was effective in identifying a very small number of athletes in whom continued participation in sports activities was thought to be dangerous.
  3. Inclusion of the ECG in the initial screening evaluation was important.
  4. The screening program was practical and the costs were reasonable.

 

My Thoughts

This study provides some pertinent data to help frame our discussions about cardiovascular screening for adult, recreational athletes.  The study population here appears to be typical in many regards, and I suspect the study results can reasonably be generalized to athletic populations far beyond Switzerland.

Adult, recreational athletes are not typically bound by the mandatory pre-participation cardiac screening programs that are used for young, competitive athletes.  They have to make their own decisions in this regard.  They must decide whether “getting checked out” is worth the expense.  Athletes might have a variety of relevant questions.  How likely am I to discover a previously unrecognized cardiac problem–particularly if I don’t have any symptoms?  What are the chances that I could be a false-positive–with the burden of additional diagnostic testing to sort things out?  What will this all cost?

Each of these questions now has an answer.

With regard to the first question, there is an approximately 3% chance of identifying a previously unrecognized, unsuspected, and presumably asymptomatic, cardiovascular condition.  On t op of that, there is an approximately 4% chance of identifying a high risk profile, based on risk factors, that deserves close follow-up.  And finally, there is an approximately 0.4% chance (3 athletes among 785) of identifying a serious cardiovascular condition that places an athlete at undue risk of sudden cardiac death during exercise.  It’s not clear from the study whether these risks are similar for men and women.

The second question also has an answer.  The chance of a false-positive, using this particular screening evaluation, was approximately 11.5% (90 athletes among 785).  That is a fairly large number.  Recall that each of these athletes required additional diagnostic testing–at additional cost–to establish that they didn’t actually have a problem after all.

The third question has also been answered–at least in Switzerland.  The average cost of the screening program–initial evaluation plus the costs of additional testing that was needed–was $199 per athlete.  The cost for the 663 athletes who had a normal screening evaluation was only $130.  Obviously, the costs for the remaining 122 athletes, with an abnormal screening evaluation, and who required additional diagnostic testing, were greater.  All of these costs would be much higher in the United States, I suspect, and this issue is compounded by the fact that most health insurance policies don’t cover screening evaluations such as these.  For many American athletes, these expenses would be out-of-pocket.

At any rate, this new information will be helpful as athletes have discussions with their physicians about whether or not to pursue cardiac screening.

Those are my thoughts about the issue from the athlete perspective.

From the physician perspective, I think it’s important to note that all of the stress testing results were normal.  These are expensive tests.  We need to keep in mind that the pre-test probability of an abnormal finding in an asymptomatic population of exercisers is extraordinarily low.  Perhaps, it’s best to think twice before ordering a stress test in this situation.

And finally, from the perspective of the event organizer, the prevalence data here is enlightening.  Governing bodies and race directors should be aware that several percent of participating athletes will have unsuspected cardiovascular problems, including 0.4% who are at high risk of sudden cardiac death during exercise.  These numbers should inform safety planning efforts.  It shouldn’t be surprising that we have a small number of cardiac emergencies and even fatalities in recreational competitions involving adult athletes.

 

Reference:

1.  Menafoglio A, Di Valentino M, Porretta AP, et al.  Cardiovascular evaluation of middle-aged individuals engaged in high-intensity sport activities:  implications for workload, yield and economic costs.  Br J Sports Med 2014;01-6.  doi:10.1136/bjsports-2014-093857.

Gender Differences in Sports-Related Sudden Cardiac Death

 

A Research Letter was published in last week’s Journal of the American Medical Association that provided updated information about the French experience with sports-related sudden cardiac death (SCD) in the general population.  I’ve talked here at the blog previously about reporting by this group of investigators on their comprehensive study from 2011.

Last week’s report focused on the time period from 2005 to 2010.  The investigators identified cases of SCD during moderate to vigorous exercise among athletes who were primarily recreational, rather than competitive, athletes.  Overall, 775 incidents of SCD were identified.


The incidence of sports-related SCD per million participants per year was:

2.96 for athletes aged 15-34
6.63 for athletes aged 35-54
7.51 for athletes aged 55-75.

and

5.45 for all athletes, overall.


But looking at gender, the incidence of sports-related SCD per million participants per year was:

10.07 for men

and only

0.51 for women.

During the study period, the 3 most common sports activities for women were cycling, jogging, and swimming.  For those sports, the incidence of sports-related SCD per million participants per year were all  less than 0.5.  In contrast, the incidence of SCD for men in those sports was 6.5, 4.7, and 0.9, respectively.

Implications

There are at least a couple possible explanations.  First, there may just be something different about men and women when it comes to predisposition to SCD.  One obvious difference is the greater prevalence of coronary artery disease in adult men compared to women, but there may be other such differences as well.  Another possibility is that, on a population basis, the intensity of exertion during participation might be different for men and women.

Regardless of the explanation, though, there is an implication with respect to screening.  One of the criticisms of routine cardiac screening for young competitive athletes–yet alone, for recreational athletes–has been the limited resources and associated costs of physical examinations and diagnostic tests such as EKG’s or echocardiograms.  Knowing that the risk of sports-related SCD may be 10+ times greater for men than for women and several-fold greater for athletes older (rather than younger) than 35 years might help us focus our screening efforts on the portion of the recreational athlete population that is at greatest risk.