In the months following the Vertical Blue 2023 luggage search of Croatian freediving athletes Vitomir Maricic, Petar Klovar, and Sanda Delija, freedivers took to social media and online platforms to debate the performance-enhancing effects of the drugs allegedly found in their luggage.
Unfortunately, this is a largely unexplored topic due to the limited scientific research on freediving.
The purpose of this article is to take a deeper look into how medications get placed on the World Anti-Doping Agency’s (WADA) Prohibited List, understand the different types of evidence in medicine, explore clinical studies related to each of the substances that have become the topic of online discussions, provide input from medical professionals on the use of furosemide in treating freediving-related lung conditions, and hear from Maricic on the substances from the July 4th luggage search.
Freediving Doping Controversy
After 12 months of extensive investigation, including over 400 hours of research and interviews by author Kristina Zvaritch, DeeperBlue.com is exclusively releasing this four-part series about doping in freediving. The series is inspired by the events that preceded the 2023 edition of the renowned Vertical Blue freediving competition and its aftermath. Kristina received no compensation for this investigation.
The series includes the following articles:
- Freediving Doping Controversy: Part 1 – Everything You Need to Know About Vertical Blue 2023
- Freediving Doping Controversy: Part 2 – What Happened to Tory George?
- Freediving Doping Controversy: Part 3 – Examining the Drugs in Question (this article)
- Freediving Doping Controversy: Part 4 – When Ethics Are Forgotten
While this article delves into technical details about doping substances and medical evidence, you can jump straight to the summary for a brief, non-technical overview of the findings.
Substances on WADA’s Prohibited List
WADA reviews its Prohibited List annually, consulting scientific, medical, and anti-doping experts. This list undergoes constant review to adapt to new scientific research and information from various sources.
First, for a substance to be added to WADA’s Prohibited List, it must be placed in the Monitoring Program to “detect potential patterns of misuse in sport.” A proposed substance must be deemed to fulfill two of the following three criteria:
- It has the potential to enhance or enhance sports performance.
- It represents an actual or potential health risk to the Athlete.
- It violates the spirit of sport (this definition is outlined in the WADA Code).
WADA’s Prohibited List is long and extensive, and not every drug listed is inherently harmful or clearly and visibly performance-enhancing. And while the public often sees elite freedivers as healthy individuals with no need for drugs, there are medications on the list that both non-competitive freedivers and non-freedivers may be using, unaware that they’re on WADA’s Prohibited List.
For example, I use spironolactone to treat hormonal acne – other women use it to treat female pattern hair loss. I was surprised to find that it is on WADA’s list as a diuretic and masking agent. Some women use Clomifene for fertility, which is listed as an anti-estrogenic substance on the Prohibited List. If someone takes peptide hormones to heal faster from an injury – you will find those on the list. A diabetic freediver who uses insulin? Yes, it is indeed on the Prohibited List as a metabolic modulator.
Since substances on the Prohibited List include medications that people need to function in everyday life, WADA created Therapeutic Use Exemptions (TUEs) – waivers granted to athletes that allow them to use substances or methods that are otherwise prohibited by anti-doping regulations due to an underlying medical condition.
As stated previously, some medications are necessary because athletes have physical or mental conditions that require medication for legitimate therapeutic reasons. The ultimate goal of the TUE process is to create an environment where competition is fierce yet fair and where an athlete’s health needs will never stop them from participating.
Readers should note that WADA offers a free Anti-Doping Education and Learning (ADEL) platform with programs targeting athletes, coaches, parents, medical professionals, and more. Register and join ADEL to learn more about how WADA protects clean sport.
Alleged Substances Found in the Vertical Blue 2023 Luggage Search
On July 4, 2023, a group of freediving athletes arrived on Long Island, Bahamas, for the annual Vertical Blue competition, and William Trubridge, the event organizer, intercepted them. These athletes were told they needed to undergo a ‘gateway check’ luggage search and subsequently had their baggage inspected by Trubridge and two armed police officers. Trubridge wrote down the substances that were allegedly found in their belongings. At the same time, Croatian athletes Vitomir Maricic and Petar Klovar stayed behind to undergo doping control by a Bahamas Anti-Doping Commission doping control officer.
Three days later, Vertical Blue released an official statement on its Instagram page regarding the luggage search, which listed both Croatian athletes by name.
The official statement reads, “During the search, four (4) known Performance Enhancing Drugs (PEDs) were discovered in the luggage of both athletes. These included substances that are on the WADA banned list for all sport, as well as other prescription drugs that are known to be PEDs for freediving, and are included on the banned list for VB according to its doping policy.”
The four medications were as follows:
- Sildenafil – Part of the phosphodiesterase type 5 (PDE5) inhibitor drug class, sildenafil is primarily used to treat erectile dysfunction.
- Diazepam and alprazolam – Belonging to the benzodiazepine drug class, they are used to treat anxiety, mental health-related conditions, and seizures.
- Furosemide – Classified as part of the loop diuretic drug class, it treats and manages fluid overload conditions.
Readers should note that of the four medications listed above, only one appears on WADA’s Prohibited List for 2023—furosemide. However, furosemide isn’t listed as a performance-enhancing drug; instead, it is listed in the ‘Diuretics and Masking Agents’ class.
The rest belong on the list provided in VB Doping Control Policy and Procedures (a document unique to Vertical Blue that stated that along with WADA’s prohibited list of substances, there were additional prohibited drugs, possible random baggage searches, and more).
Vertical Blue’s list includes:
- All substances currently banned by WADA
- Thioamides and other prescribed thyroid suppressants
- Benzodiazepines (e.g. Xanax, Valium)
- Beta-blockers (BBs) and calcium channel blockers (CCBs)
- Any prescription-only substance that enhances performance in apnea/freediving and for which the athlete does not have a current prescription.
Why Vertical Blue created its own additional prohibited list
I asked Trubridge what his concerns and suspicions were in the lead-up to Vertical Blue 2023. He told me, “The concerns and suspicions were that people who were intending on coming to the event and maybe taking performance-enhancing substances. Not only the performance-enhancing substances that are on the WADA List and currently banned for freediving, but also performance-enhancing drugs by the definition of a prescription pharmaceutical. For instance, benzodiazepines were one of these clusters of drugs that aren’t banned for freediving or any other sport. And we started to hear that at the end of 2022, others were talking openly about the use of benzodiazepines.”
“So there was a group of freedivers who said, ‘Hang on a minute, that’s a drug with a lot of side effects.’ So it classifies as a potentially harmful substance and has a performance-enhancing effect. If that’s the only reason athletes are taking it, it’s no different to taking any of the other substances on the list. It makes sense if something is anti-anxiety and has been shown to slow down the heart rate would have a performance-enhancing effect on freediving. So that was one of the substances that we decided wouldn’t be tolerated at Vertical Blue.”
However, while furosemide is a WADA-banned substance and benzodiazepines were listed by name in the Vertical Blue Doping Policy and Procedures, sildenafil was notably absent from the list.
In an interview, Trubridge confirmed that sildenafil was under the category of “any prescription-only substance that enhances performance in apnea/freediving.”
“Sildenafil isn’t actually listed in the Vertical Blue Policy and Procedures,” Trubridge told me. “But that was something that we then (kind of in the course of research and actually discovering it in the luggage of the Croatians), we then did kind of research on it. And there were studies that show that in regular sport, it doesn’t do anything. But in sports where there is hypoxia, such as endurance sports at altitude and low oxygen, then it does have a benefit. And so, it was obvious that there was a potential that this was a PED.”
In other words, the investigation into sildenafil’s possible performance-enhancing effects in freediving only began after its alleged discovery in the Croatian athletes’ luggage.
I asked Trubridge, who concluded that sildenafil has potential as a PED, and he informed me that it was “advisors, most of them doctors or research scientists.” Among those experts were Dr. Frank B. Pernett, a Pulmonary Medicine specialist and Ph.D. candidate, and Dr. Juan D. Guerrero, a General Physician and competitive athlete.
Types of Evidence in Medicine
In medicine and healthcare, many types of evidence are used to inform practices, treatments, and decision-making; however, not all types are equal. Below, we will discuss clinical guidelines, clinical studies, expert clinical opinion, anecdotal evidence, and the value of each type of evidence in healthcare.
Clinical guidelines
Clinical guidelines are carefully-created recommendations that help doctors and patients decide on the best healthcare for specific medical situations. They are created by committees of clinicians practicing in a particular field with academic and clinical knowledge. Within clinical guidelines are literature reviews of all clinical studies of specific disease states, assessments and ratings of clinical studies based on the quality of evidence, and clinical recommendations based on the quantity and quality of evidence to support the recommendation.
An example of a well-established clinical guideline is the American Diabetes Association’s Standards of Care in Diabetes 2023.
In an ideal world, we would have clinical guidelines for freediving medicine based on clinical studies of freedivers, with recommendations in the guidelines rated according to the quality of evidence found in a comprehensive literature review. The guidelines would consider treating the patient’s ailment best while avoiding therapies that have demonstrated performance enhancement potential in freediving. Providers could use the guidelines’ recommendations and clinical experience to tailor the treatment best to help the patient.
However, clinicians today are far from being able to make strong recommendations on freediving-related diseases based on current evidence. For example, see UHMS’ Best Practice Guidelines on the Prevention and Treatment of Decompression Sickness and Arterial Gas Embolism. Their introduction states, “The committee carefully reviewed evidence that was available. However, for many of the issues, there was little or no published scientific evidence upon which to base recommendations. Therefore, evidence for the current recommendations is based mainly on expert opinion (American Heart Association Class II, level of evidence C).”
Clinical studies
Clinical studies (also known as clinical trials or clinical research) are research investigations where people volunteer to test new treatments, interventions, or tests to prevent, detect, treat, or manage various diseases or conditions. An optimal clinical study in freediving would include many participants who represent typical competitive freedivers, and a statistician would help design the study to get meaningful results. If possible, the study would use random selection and keep researchers and participants unaware of who gets the treatment. It would also be helpful to use a placebo for comparison. These factors would provide more reliable and valid results.
When discussing drugs that theoretically enhance freediving performance, I asked various medical professionals and researchers if they knew of any published studies about the safety or performance-enhancing effects of the substances mentioned in this article for freedivers. None of them could provide such studies. I also searched for these studies myself but couldn’t find any.
Expert clinical opinion
Expert clinical opinion involves the judgment and recommendations of highly experienced healthcare professionals or specialists in a particular medical field. However, expert opinions about a drug’s performance-enhancing effects are not a reliable substitute for clinical studies. A single medical provider’s expert clinical opinion may lack objectivity or be influenced by personal bias (for example, if a medical provider actively competes in freediving competitions, they would be naturally biased). It can also be limited due to a narrow scope of practice or specific patient population. Furthermore, a medical provider’s expert clinical opinion can be outdated if the medical provider doesn’t keep up with the latest research.
While expert medical opinion can still be valuable, it cannot replace a well-conducted clinical study.
Anecdotal evidence
Anecdotal evidence comes from one or more individuals’ personal experiences. It is the least reliable and lowest-quality type of evidence in medicine. It does not include control groups or standardization, and the reporter’s experience may simply be a matter of chance. It is not peer-reviewed, is heavily subject to bias, and does not account for variables such as other medications taken, lifestyle factors, and underlying health conditions.
This means that even if a few individuals report improved performance after using a substance, it is not proof it will work for everyone.
Clinical Studies Involving Sildenafil, Benzodiazepines, and Furosemide
NOTE: All clinical information in this article has been reviewed for accuracy by a board-certified clinical pharmacy specialist intimately familiar with the ethics of medical research.
Sildenafil
Sildenafil was one medication allegedly found in one of the athletes’ luggage on July 4th at Vertical Blue 2023. More commonly known by its brand name Viagra, sildenafil is not banned by WADA. William Trubridge, the event organizer of Vertical Blue 2023, confirmed to me that on the VB Doping Control Policy and Procedures, sildenafil fell under the category “any prescription-only substance that enhances performance in apnea/freediving and for which the athlete does not have a current prescription.”
Indications
According to drug information provided by Merative, Micromedex as published in Mayo Clinic, sildenafil is approved for two indications: pulmonary arterial hypertension and erectile dysfunction. Among other off-label uses, the Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update suggest sildenafil may be considered as a possible off-label treatment option to prevent or treat High Altitude Pulmonary Edema (HAPE), a form of severe high-altitude respiratory illness in mountaineers. However, this would be the fourth-line option behind descent, supplemental oxygen administration, and nifedipine. Depending on the reference utilized, sildenafil is assigned either a weak recommendation based on low-quality evidence or is not recommended.
Sildenafil and exercise
One study by researchers from the University of British Columbia reviewed 14 published studies regarding sildenafil and exercise. The conclusion of the study showed that the vasodilatory effect of sildenafil helps reduce pulmonary artery pressure (where deoxygenated blood is transported from the right heart ventricle to the lungs) during workouts and at rest. It also increases the cardiac output (i.e., making the heart more efficient) during exercise. It moderately improves blood oxygen saturation (i.e., increases the oxygen level in the blood) at high altitudes. However, researchers stated it did not affect performance overall.
This is also true of another study conducted by WADA, which concluded that “sildenafil is unlikely to exert beneficial effects in oxygen delivery or exercise performance at altitudes < 4000 m for the vast majority of the endurance-trained men or women.”
NOTE: While sildenafil has been shown to improve blood flow and oxygen levels at high altitudes, the pharmacist who reviewed the clinical studies informed me we cannot assume that those benefits apply to a sport that takes place entirely underwater where athletes hold their breath.
Anecdotal reports regarding sildenafil aiding in recovery
Social media users allege that sildenafil may have performance-enhancing potential by helping the athlete recover faster from depth sessions. This, in turn, could help them progress in depth faster than an athlete who is not taking prescription medications for recovery.
While I wasn’t able to find any studies studying the use of sildenafil for this application, anecdotal information discussed in the freediving community suggests that taking sildenafil before a dive is unsafe and may predispose an athlete to an increased risk of pulmonary barotrauma (a lung injury caused by pressure changes during deep dives, often referred to as a ‘lung squeeze’ by freedivers).
Potential side effects
A 2013 study showed an increased risk of decompression sickness (DCS) in rats when using sildenafil before being “exposed to compressed air to induce decompression stress and bubble formation.” Researchers initially hypothesized that sildenafil could “have a beneficial role on decompression by reducing bubble formation.” However, after administering sildenafil to rats and subjecting them to compressed air to induce decompression stress and bubble formation, researchers discovered that “pre-treatment with sildenafil promotes the onset and severity of neurological DCS. When considering the use of phosphodiesterase-5 blockers in the context of diving, careful discussion with a physician should be recommended.”
Conclusions
Due to the known potential risks based on animal studies, it would be unethical to conduct a clinical study on sildenafil in relation to diving activities. Therefore, any claims about sildenafil being performance-enhancing could never be evidence-based, as no researchers would participate in a clinical study that could harm humans.
Moreover, the pharmacist who reviewed these studies told me that the benefits observed in high-altitude studies cannot be assumed to apply to freediving, an underwater sport involving breath-holding rather than continuous breathing.
Benzodiazepines
Diazepam and alprazolam, the substances allegedly found in luggage at Vertical Blue 2023, both fall under a class of medications called benzodiazepines. Benzodiazepines are on Vertical Blue 2023’s list of prohibited substances – WADA does not currently ban them.
Indications
According to Australia’s Alcohol and Drug Foundation, benzodiazepines are depressant drugs that “slow down the messages traveling between the brain and the body.” They are also “minor tranquilizers, usually prescribed by doctors to relieve stress and anxiety and to help people sleep.” According to Mayo Clinic, frequent travelers may also use them to help with jet lag and adjust to a new time zone.
Benzodiazepines are classified as controlled substances due to their potential for abuse, misuse, and addiction potential.
Benzodiazepines in sports and archery
Trubridge stated to me that benzodiazepines should be considered a PED in freediving because they possess anti-anxiety properties, which could be regarded as helpful due to a lowered heart rate. However, studies on the effect of benzodiazepines in archery seem to show the opposite. Although archery and freediving are fundamentally different sports, both require mental focus, concentration, physical control and precision, and stress and relaxation management – all of which benzodiazepines could be hypothesized to benefit.
In an article titled “The role of tranquillizers in sport and exercise,” the author concluded that “Tranquilizing drugs do not appear on the International Olympic Committee’s list of banned substances primarily because there is no evidence to suggest that they possess direct performance enhancing properties.”
The author goes on to state that “the general observation is that the tranquilizing drugs can impair psychomotor performance, motor ability, maximal isometric strength, and maximal power output both immediately after ingestion and up to 36 h afterward.”
In another WADA study titled “Effects of Anxiolytics on Fine-Tuning (Neuromuscular) Activity Performance,” researchers investigated rumors that some archers used anxiolytics to diminish anxiety and reduce body sway when taking a shot, which could positively affect performance. Elite archers were given benzodiazepines or a placebo to evaluate the effects of anxiolytics on their performance. Researchers concluded that “the results did not show any difference between the groups, neither in physical performance characteristic nor in other parameters.”
The conclusion also stated that diazepam was given in a single, relatively low dose of 5mg because “since benzodiazepines cause sedation and inhibition of motor activity in higher doses, they are expected to negatively affect motor performance in athletic competitions requiring fine-tuning skills.”
The data also showed that the resting heart rates of archers who had taken diazepam were unaffected, and there were no marked changes in heart rates while shooting.
Risk of dependence
What numerous studies have found on benzodiazepines is that they are highly addictive and have a high potential for abuse, as is reflected in the 2022 study “Benzodiazepines in sport, an underestimated problem: Recommendations for sports medicine physicians’ practice,” researchers concluded the study with a nine-point list of recommendations for sports medicine physicians “to help [athletes] in future situations which entail benzodiazepine prescription, the recognition of addiction, and intervention strategies” since “benzodiazepines are among the most commonly prescribed medications for insomnia and anxiety.”
Conclusions
The studies above conclude that low doses of benzodiazepines showed no marked changes in physical performance in archery and that higher doses would go on to affect psychomotor performance and other factors negatively.
While these effects are not dangerous in archery, they present a serious danger in deep freediving. Additionally, the potential for addiction and abuse is something to be considered by prescribing physicians.
I also reached out directly to WADA to ask if they had ever considered adding benzodiazepines to the Prohibited List. They told me that a substance must meet two of the following three criteria to be considered for inclusion:
- It has the potential to enhance or enhance sports performance.
- It represents an actual or potential health risk to the Athlete.
- It violates the spirit of sport (this definition is outlined in the WADA Code).
The WADA representative went on to state that “currently, there is no indication that benzodiazepines fulfill two of the three criteria.”
Furosemide
Furosemide is a prescription drug that is currently on WADA’s 2023 Prohibited List under ‘S5 – Diuretics and Masking Agents’ class.
Indications
According to Mayo Clinic, furosemide is a loop diuretic “given to help treat fluid retention (edema) and swelling that is caused by congestive heart failure, liver disease, kidney disease, or other medical conditions.” Mayo Clinic’s page on pulmonary edema states that “diuretics, such as furosemide (Lasix), decrease the pressure caused by excess fluid in the heart and lungs.”
Diuretics in sports
Diuretics are “medicines that help you move extra fluid and salt out of your body,” and they do so by making you urinate more frequently, as stated by Cleveland Clinic. With regards to the use of diuretics in sports, a 2010 study found that “although there is little evidence of athletic performance enhancement following diuretic administration, their abuse is widespread among athletes who want to lose weight quickly.”
While this can be helpful in wrestling and boxing (where weight categories exist), dehydration is dangerous in freediving due to immersion diuresis (the urge to urinate), sweating in a wetsuit, and breathing through the mouth. According to DailyMed, furosemide is well-documented to cause significant drops in blood pressure and electrolyte imbalances, among other adverse effects.
Diuretics as a masking agent
Given that diuretics can be used to mask doping agents by reducing their concentration in urine, a 2021 study posed the question, “Can furosemide mask the use of performance-enhancing drugs?” Researchers concluded that “the masking effect of furosemide is limited. Furosemide is a doping agent that is mainly relevant for sports with weight categories.”
This conclusion is further corroborated by a paper from 2010 titled “The abuse of diuretics as performance-enhancing drugs and masking agents in sport doping: pharmacology, toxicology and analysis.” The authors stated, “In the 1990s, the analysis of diuretics in doping (by LC-UV or GC/MS) was a challenge for anti-doping laboratories due to the heterogeneity of the substances included. Since the advent of robust and reliable LC/MS instruments their detection in urine samples is no longer a problem.”
In simpler terms, detecting diuretics in urine samples for doping control was difficult years ago, but advanced technology has made it much easier to detect today. So much so that trace quantities of six specific diuretics, including furosemide, which can be present as contaminants in both prescription and over-the-counter medications, “may be sufficient to cause an Adverse Analytical Finding in a Sample collected from an Athlete who took such a product, due to the improved sensitivity of the testing methods used by WADA-accredited laboratories.”
To address this issue, WADA-accredited laboratories had to establish minimum reporting levels for these diuretics (20 ng/mL, a dose that wouldn’t be able to mask the presence of another prohibited substance in a sample) so that they wouldn’t trigger Adverse Analytical Findings or Atypical Findings in athlete samples.
Conclusions
A study on diuretics in sports shows little evidence of performance enhancement in athletes after ingesting diuretics – they are used mainly by athletes who want to lose weight quickly. Diuretics are also readily detectable in modern-day doping control.
Furosemide as Pharmacotherapy for Freediving-Induced Pulmonary Syndrome
Freediving lungs at great depths
While some social media users suggested that the accused athletes likely used furosemide as a masking agent for other substances, others mentioned that furosemide is also sometimes used as a treatment for pulmonary edema or pulmonary barotrauma.
In deep freediving, blood shift, pulmonary edema, and pulmonary barotrauma are not separate conditions but different levels of the same process.
Blood shift
When freedivers dive deeper than the point their lungs reach residual volume, blood shifts from the arms and legs to the core, mainly into the lungs, causing pulmonary capillaries to become very engorged and dilated with blood. At the same time, air spaces experience negative pressure, drawing fluid in—this is called the ‘blood shift’ and is a natural occurrence of freediving past residual volume depth.
Pulmonary edema
Depending on the fluid build-up in the lungs, this can turn into pulmonary edema. Pulmonary edema is defined as the abnormal buildup of fluid in the lung tissue (‘parenchyma’), which is expected to some degree after very deep dives in freediving. Pulmonary edema can be due to cardiogenic (heart) or non-cardiogenic (lung) issues – the fluid is the same, but what separates them is the root cause.
Pulmonary barotrauma
When there is too much negative pressure or too much stress on the vessels, blood can leak out of the vessels and into the air spaces, resulting in pulmonary barotrauma (also referred to as a ‘lung squeeze’ in freediving). Pulmonary barotrauma can range from mild to severe, and the treatment and recovery times depend on the severity and any resulting complications.
Expert clinical opinions
I followed up with three physicians with experience in pulmonary and diving medicine to get their thoughts on furosemide as a pharmacological treatment for pulmonary edema. Additionally, I asked Croatian athlete Vitomir Maricic, one of the athletes whose luggage was searched by Vertical Blue 2023’s event organizer, William Trubridge, and armed, off-duty Royal Bahamas police officers.
All four individuals were invited to speak at and attend the “Barotrauma and SIPE in Freediving” workshop in San Diego, California, on October 27 – 28, 2023. At this workshop, sponsored by Divers Alert Network (DAN) America and the University of California San Diego Center for Excellence in Diving, researchers, educators, athletes, and scientists gathered to combine their collective knowledge and coin the term ‘FIPS,’ which stands for ‘freediving-induced pulmonary syndrome.’
According to the workshop proceedings, FIPS can include “components of SIPE/IPE [swimming-induced pulmonary edema/immersion pulmonary edema], Barotrauma (ascent or descent), aspiration and other still unresolved pathophysiological mechanisms.”
Dr. Richard Moon, MD, FACP, FCCP
Dr. Richard Moon, a clinical anesthesiologist, pulmonologist, and the Medical Director of the Duke Center for Hyperbaric Medicine & Environmental Physiology, explained that non-cardiogenic pulmonary edema occurs in freedivers from excessively elevated pulmonary capillary pressure.
For treating pulmonary edema in freedivers, Dr. Moon told me that “measures include administration of oxygen, noninvasive ventilation (for example, CPAP), and in severe cases, endotracheal intubation. In addition, administration of drugs to lower pulmonary capillary pressure may be used.” He went on to say that “in freedivers, pulmonary capillary pressure returns to normal soon after exiting the water, so in most instances, oxygenation could be maintained while the body resolves the edema by simply administering oxygen with or without CPAP.”
Dr. Moon concluded by saying that if the above measures are not adequate, furosemide may be helpful in extreme cases to reduce pulmonary capillary pressure further. This information can also be found in the consumer version of the MSD Manual on treating Swimming-Induced Pulmonary Edema, authored by Dr. Moon.
Dr. Fernando ‘Bizo’ Silva, MD, MS, DiDMM
Dr. Fernando ‘Bizo’ Silva, an Emergency Medicine specialist and diplomate in Diving and Marine Medicine specializing in lung ultrasounds and lung injuries, has experience on the medical team in various competitions.
He worries about freedivers’ vasomotility (i.e., the ability of blood vessels to expand and contract to regulate blood flow and maintain blood pressure in the body) after a deep dive. While in the emergency room, diuretics are often used to treat pulmonary edema. Dr. Silva mentioned that freedivers who have encountered pulmonary edema from a deep dive should be treated differently since their vasomotility is affected after deep dives due to blood shift and the mammalian dive reflex.
“When you come up from a deep dive, your vasculature, or how the arteries squeeze and maintain under pressure, is impaired,” Dr. Silva explained. “And diuretics not only cause you to urinate, they also have an effect on how arteries squeeze. That means we may interfere with this process if we give diuretics within minutes after a deep dive, which could result in changes in the vasomotility such as dangerously low blood pressure or a lack of responsiveness of the arteries squeezing. That’s why I say that giving diuretics and other medications that affect vasomotility is potentially very catastrophically dangerous for freedivers – at least until I have more information.”
Dr. Igor Barkovic, MD, Ph.D., Assistant Professor
Dr. Igor Barkovic is a pulmonologist and critical care specialist who heads the Centre for Research and Education in Undersea, Hyperbaric, and Maritime Medicine in Rijeka, Croatia. He has spoken at various conferences and authored multiple scientific research papers on breath-hold diving.
He is also the physician who prescribed Vitomir Maricic and Petar Klovar furosemide for use in especially remote locations in extreme emergency situations in this letter.
Dr. Barkovic informed me that pulmonary edema in deep freediving results from the gorge of blood that comes to the thorax and enters pulmonary circulation. He sees this as parallel to cardiogenic pulmonary edema, where the first line of treatment is diuretics because the heart has less work to do removing the blood from pulmonary circulation.
“Drawing parallels is the most you can do if there are no results, so we made a parallel to cardiogenic edema,” Dr. Barkovic told me. “Vitomir and Petar go to remote islands in Croatia and all over the world and ask me what they should do – I told them that they need oxygen, provided them with a CPAP machine, and prescribed them furosemide. How do I prove the three together will work? There’s no proof – no one has done it, but it’s logical to me since it’s similar to cardiogenic edema.”
“I told them not to use it beforehand because it is not helpful and doesn’t enhance results – it can even be dangerous to use it before diving. But it’s about severity. After FIPS – and only if they have such problems that they need to go to the emergency room and there is none – then they can use it on themselves. I asked my colleagues around Croatia about what they would do. 100% of the cardiologists and pulmonologists told me if they saw pulmonary edema, they would give diuretics (for example, furosemide).”
Dr. Barkovic touched on an interesting point. “This is a really narrow part of medicine, and no one in the world is an expert or knows everything about it because there is very little known about the topic,” he told me. “I’d like to stress that someone who is against it can have their own opinion, but they cannot be sure if it is good or not good because there is no evidence. It is hard to be an expert at something that humans know very little about – I don’t think that there are more than 10 – 20 people around that can perform such results as Vitomir and Petar. So we are all speaking about something we don’t know much about.”
Vitomir Maricic weighs in
Vitomir Maricic, one of the Croatian freediving athletes whose luggage was searched in the weeks leading up to Vertical Blue 2023, is a pulmonary rehabilitator who actively participates in multiple research projects concerning safety in deep freediving in the Centre for Research and Education in Undersea, Hyperbaric and Maritime Medicine in Rijeka, Croatia. He also helped design the ‘Lung Squeeze Survey’ sponsored by Divers Alert Network (DAN) and the University of California San Diego (UCSD).
Maricic’s views on furosemide
Maricic maintains that furosemide is an emergency treatment medicine for pulmonary edema. “Petar Klovar and I never actually needed to use it, and I believe the vast majority of cases in freediving can be managed without it. Using it also means you can test positive for it, so you are immediately out of any competition until you explain why you used it and get a TUE. In our case, since we are part of ADAMS, we’d have to exclude ourselves from everything since we can get tested at any time and any place and then fail doping control. So it’s not an option unless it’s really a life-saving thing.”
ADAMS stands for Anti-Doping Administration and Management System, an essential tool used by WADA and anti-doping organizations to ensure effective monitoring and implementation of anti-doping regulations. Maricic has been part of ADAMS since 2018, while Klovar joined in 2021. They estimate that in 2023 alone, Maricic had 6 to 8 in- and out-of-competition tests, and Klovar had 12 or more. Furthermore, Maricic stated to me that neither had tested positive nor missed a single control.
“A diuretic would also leave you dehydrated, and probably you wouldn’t be able to come close to any good results anyway, so in any case, using it means many complications for an athlete,” Maricic continued. “I only once saw a freediving victim where I wish I had furosemide nearby since it was very hard to keep their saturation above 80%, even with the help of oxygen. It was lucky we had enough oxygen in that case. Even though I would use this only in extremely severe cases, it would be no surprise that it would be something you get in a hospital, even for a very light squeeze, and we see it happening all the time.”
Furosemide and retroactive TUEs
Maricic also shared his interpretation of Article 2.6 of the WADA Code. In his opinion, a TUE isn’t necessary for furosemide if it’s intended for life-threatening emergencies rather than therapy. He is referring to a comment in the Code regarding Articles 2.6.1 and 2.6.2, which states, “Acceptable justification may include, for example, [a] an Athlete or a team doctor carrying Prohibited Substances or Prohibited Methods for dealing with acute and emergency situations [e.g., an epinephrine auto-injector].”
Furthermore, Article 4.1 of WADA’s International Standards for Therapeutic Use Exemptions allows athletes to apply for a retroactive TUE (“a TUE for a prohibited substance or prohibited method after using or possessing the substance or method in question”) if a prohibited substance is used or in their possession for emergency treatment.
“All prescribed medications come with official documents issued with them; furosemide is one of those, just like benzodiazepines or any other medicines you need a prescription for,” he told me. “I personally told this to William Trubridge on several occasions after he himself asked if we had the documentation for the medications we carried. I answered ‘yes’ in front of everyone there, but he never bothered to ask us again or check anything. In fact, it seemed he did not really want to hear this and was hoping we would say no. Later, it became clear to me that for his plan, it was irrelevant. The goal was to get us in trouble, not to investigate or to fight doping.”
Conclusions
It is clear that the topic of how to treat FIPS is still majorly unexplored, and physicians of different specialties and backgrounds differ in their approaches to managing the condition regarding freediving. Multiple participants of the “Barotrauma and SIPE in Freediving” workshop stated that discussions left them with more questions than answers. However, there is hope that this workshop is the first step and that more research will follow to understand FIPS better and provide guidance in its management.
Vertical Blue’s Location
It is important to note that Vertical Blue takes place in Dean’s Blue Hole in Long Island, Bahamas. At this remote location, a fatal accident occurred during the 2013 edition of the competition. Nicholas Mevoli was pronounced dead at the Deadman’s Cay Clinic on Long Island following his no-fins dive to 72m (236ft). Autopsies attributed his cause of death to “pulmonary hemorrhage due to barotrauma.”
Furthermore, an athlete who participated in Vertical Blue in recent years suffered a severe case of FIPS. According to a report from Vertical Blue’s Chief Medic, the island is quoted to have “very poor medical provision. There is no hospital, and only a clinic. There is one physician for the whole island. They are not accustomed with managing very sick patients.”
It went on to state that getting an X-ray or CT scan on Long Island is impossible. Therefore, in a very serious medical emergency, it appears that the only way to get the necessary medical care would be to get airlifted to either Nassau, Grand Bahama, or the United States, potentially taking hours to reach a hospital equipped for such an emergency.
Vitomir Maricic on the Alleged Substances
I had questions about the substances allegedly found in the Croatian athletes’ bags. When I contacted Vitomir Maricic in December 2023, he informed me that his lawyer advised him not to speak publicly. In September 2024, I again contacted him and asked him the following questions, and I published his answers as he told me.
I also tried Petar Klovar, who declined to comment, stating, “The reason I don’t feel inclined to comment is because emotions and ego are what created this scandal/situation in the first place. My comments and opinions are not of great use because they are subjective. My only interest is for facts to finally come out so people can realistically look upon this situation and create their own opinions.”
Have you ever used performance-enhancing drugs?
“No, not only have we never used them, we strongly advocated against it with the athletes that have confessed to us to using them. Of course, we are talking about potentially performance-enhancing drugs, not the actual performance-enhancing drugs that are banned – we would discontinue any kind of work or collaboration with them.”
“I personally had a bad experience when I started freediving, coaching a guy who was using actual performance-enhancing drugs while he was swimming (in his swimming career before he started freediving). After, he failed a doping control in freediving. Of course, without knowing any of this, this experience was one of the worst coaching experiences in my career. The disappointment that I had after in this athlete – I definitely make sure to always ask people and to make it clear that I need to know everything they’re taking. In case it’s something that’s actually performance-enhancing and banned, then we’re not working together, and that’s it.”
“In my opinion, there is a reason why these drugs [benzodiazepines and sildenafil] are not listed as performance-enhancing – because they are not. And the athletes who experiment with them have more of a placebo effect, being unaware that any drug can alter our natural homeostasis, which in my opinion, is never good in sports, as it can have negative side effects.”
“Anyone who has spent some time training with us knows that we rely on a lifetime of sport, modern training principles, and a positive mindset with a playful and experimental approach to competing.”
Did your team have furosemide, benzodiazepines, and sildenafil in your luggage on July 4, 2023?
“Yes, some of the substances we did indeed carry with us, as recommended by our medical team.”
Why did you have these substances in your luggage?
“We can’t really put all substances under a common denominator – sildenafil has a very known usage. Benzodiazepines as well can be useful with many neurological and muscle-related issues, as well as helping restore a circadian rhythm, which is important to athletes often traveling between continents. Diuretics can be a life-saving measure in cases that can occur in freediving, and having these drugs with you in locations like remote Caribbean islands where no hospital or proper pharmacy is available. All these things are very easy to check to anyone with a critical mind and the reasoning to understand right from wrong sources.”
“None of these drugs is in any way performance enhancing, in fact, it is detrimental to freediving performance and can be dangerous, which is also very clear to anyone who actually wants to think about it.”
Do you have prescriptions for these medications?
“Yes, of course, for anything we carry across borders, if needed, we have all the right medical documentation to legally have it with us. With having these medications, we never had any advantage over any competitor, nor have we used them or would recommend them to be used for freediving performance. Even the WADA Code has an extra section on possession, which deals specifically with substances like furosemide.”
Upon request, Maricic provided me with the documentation of all the prescriptions except for sildenafil.
Have you ever taken furosemide?
“We have never actually taken furosemide or any other diuretic. Luckily, we never had such an emergency that we would need it. Furosemide is taken in specific cases of lung squeezes where other means of recovery are not possible. Taking it outside of a life-threatening scenario would be absurd. Firstly, it is very detrimental to any kind of sports performance, and secondly, we would need to step out of any competition circuit because, since we can get tested on a daily basis, we could also fail a control in case we take furosemide any minute.”
“Of course, we could eventually get a TUE in this case, but you can’t get a TUE in 5 minutes and we can get tested anytime, anyplace, since we are in the most strict WADA ADAMS category. So, taking this anywhere can put us at risk of failing a control. Hiding a substance with furosemide makes no sense for exactly the same reason. A long time ago, when these substances were not so easily detectable, this was more commonly used – now, its only purpose is in weight-category sports, where extreme dehydration from a diuretic can drop your weight category, other than the actual medical use, which is, among other things, specifically used for lung edema.”
“This is also easy to check, and many freedivers have this experience themselves, as they get furosemide when they are ‘evacuated’ to a hospital for lung squeeze. This is done ‘just in case’ and as part of standard procedure, since hospitals are not too familiar with lung squeezes, so they do it to protect themselves in a way. In reality, 99.9% of these diving-related traumas are treated without diuretics. But there are cases where this is necessary.”
Brief Summary
For a substance to be proposed for addition to WADA’s Monitoring Program and then subsequently the Prohibited List, it must fulfill two out of the three criteria: it has the potential to enhance sports performance, it represents an actual or potential health risk, or it violates the spirit of the sport. However, some medications are necessary for people to function in everyday life, so WADA created Therapeutic Use Exemptions (TUEs).
In medicine, different types of evidence are used to inform practices. Clinical guidelines contain literature reviews of clinical studies and are rated based on the level of evidence and quality. In the absence of clinical studies, expert clinical opinion is not considered an equal substitute. Furthermore, anecdotal evidence is considered the least reliable and lowest-quality type of evidence in medicine.
When looking closely at clinical studies on sildenafil, most examine performance-enhancing benefits at higher altitudes but conclude there are no such benefits at lower altitudes. The pharmacist who reviewed the clinical studies I included told me it’s important to note that the altitude-related benefits of sildenafil in continuously breathing participants cannot be assumed to apply to underwater breath-holding sports.
Additionally, a concerning clinical study showed that administering sildenafil to rats and exposing them to decompression “promotes the onset and severity of neurological DCS,” making it unethical for researchers to perform similar clinical studies on humans in the future.
Regarding benzodiazepines, studies I found showed low doses of benzodiazepines given to clinical study participants showed no marked changes in physical performance. In contrast, higher doses would negatively affect psychomotor performance and other factors. These adverse effects would present a significant danger for freedivers at depth. Additionally, there is a high potential for addiction to benzodiazepines, which is a crucial factor physicians must consider before prescribing them.
As for furosemide, diuretics help remove extra fluid and salt from the body by increasing urine production. This can heighten the risk of dehydration, which is especially dangerous for freediving performances. A 2010 study found little evidence of athletic performance enhancement from diuretics, though their abuse is common among athletes seeking rapid weight loss for sports with weight categories. Diuretics have been administered to patients in emergency departments presenting with symptoms of pulmonary edema. While they might have been used in the past to mask doping agents, modern-day doping control easily detects their presence in urine.
Furosemide remains a typical pharmacological treatment given to patients experiencing pulmonary edema in the emergency room; however, its use for freediving-related injuries is not as clear. Three physicians had differing opinions on using it to treat freediving-related pulmonary edema and pulmonary barotrauma, and treatment in medicine often varies between physicians due to different backgrounds and experiences.
After he was asked about furosemide, competitive freediving athlete Vitomir Maricic stated that he and fellow athlete Petar Klovar have never had to use it and that the vast majority of cases in freediving don’t need it. He mentioned that it’s also not an option for them to use unless they need it since they get tested out-of-competition often throughout the year. According to the WADA Code, substances needed to treat acute emergencies can be justified. Maricic maintains that when he told William Trubridge (Vertical Blue’s event organizer and fellow athlete who searched Maricic’s and Klovar’s luggage) that he and Klovar had documentation for all medications they were carrying, Trubridge didn’t follow up on the claim.
Vertical Blue remains a remote location, unequipped to handle serious medical emergencies. US freediver Nicholas Mevoli died in a tragic accident at Vertical Blue 2013 due to “pulmonary hemorrhage caused by barotrauma.” According to a report from Vertical Blue’s Chief Medic, the island is quoted as having poor medical provision, no hospital, and only a clinic, and it isn’t used to treating very sick patients. In life-threatening situations, patients requiring urgent medical care on Long Island must be airlifted to Nassau, Grand Bahama, or the United States. This journey could potentially take hours.
I asked Maricic about the team’s use of PEDS, to which he stated they have never used them and advocated against them. As for the substances being in their luggage, he confirmed that they were and stated their medical uses and the fact that they had prescriptions for them, which I confirmed. Maricic also stated his team has never had to take furosemide and that they haven’t yet had an emergency situation where it was needed.
Final Thoughts
This in-depth look at the substances allegedly found in athlete luggage at Vertical Blue 2023 highlights the lack of clear, evidence-based guidance regarding medications and freediving performance. It also emphasizes that not all types of evidence are equal, so it is important to consider the source and, at times, conduct your research when given new information, particularly regarding potentially performance-enhancing medications in freediving.
However, some critical questions remain:
- How can policies and procedures be adjusted to eliminate gray areas that athletes might exploit while protecting their rights and medical privacy?
- Should athletes be required to disclose to the public the medications they are taking and the medical reasons for taking them in the event they are accused of doping?
- Given the lack of clinical studies specific to freediving, how should freediving organizations balance the use of medications for legitimate medical purposes against concerns about potential performance enhancement?
- When freediving organizations or competition organizers add substances to their prohibited list not yet included in WADA’s Prohibited List, how can they ensure their testing procedures align with WADA’s sample collection and analysis protocols?
As competitive freediving continues to evolve, standardized, well-researched policies are desperately needed. If freediving aims to become part of the Olympics, funded clinical studies and the creation of clinical guidelines can help ensure fair competition and athlete safety, especially in the public eye.
The final article of this series will further explore the VB2023 luggage search and doping control and aim to address unanswered questions surrounding these events.
