Apple Inc. recently announced the release of ResearchKit, an open-source software framework that is expected to enhance medical research. Apple claims its product enables everyone to take part in research that will advance medical knowledge and that it is “taking research out of the lab and into the real world.”
Mobile health technology, including wearable sensors and mobile applications, has been available for some time. Companies have been developing mobile medical applications (MMAs) for so long that the U.S. Food and Drug Administration (FDA) has already established their classifications and safety-monitoring rules and the Federal Communications Commission (FCC) has established rules and the frequency band for use with wireless body sensors. While it appears that Apple actually was lagging behind, it is encouraging that it finally joined the trend.
While vacationing in Croatia, I heard a story about a diver who fits the description of people I sometimes call “robo-divers.” The story’s hero is a famous Croatian sponge diver, with whom I share an acquaintance. My friend, who is one of his teammates, described this robo-diver’s practice, which is similar to previously described empirical dive practices of other local sponge divers: Reportedly, he does four descents per day to extreme depths, after each of which he ascends very slowly without decompression stops. After the last dive of the day, he quickly takes his boat to shallow waters (within approximately 10 minutes) and descends for about two hours of decompression, split between stops at nine, six and three meters (30, 20 and 10 feet).
I don’t know about his decompression sickness history, but I do know that he is 64 years old now, and the fact that he has survived this long following those types of dive practices make me think of him more as a robot than as a man of flesh and bone. At very least, it is unlikely that this diver has a PFO.
Between July 15-17, the Office of Naval Research (ONR) and the Naval Sea Systems Command (NAVSEA) hosted an undersea medicine progress review meeting in Durham, North Carolina. The presentations focused primarily on topics of interest for the Navy, but most of the research also benefits recreational and technical divers. One topic I found particularly interesting concerns the combined effect of increased carbon dioxide levels (CO2) in breathing gas and the breathing resistance that breathing apparatuses impose on divers.
If breathing is unimpeded, slightly increased levels of CO2 pose no problem. However, the more CO2 that is inhaled, the less CO2 can be added, and a larger breathing volume per unit of time will be required to wash out the same amount of CO2. This increase of breathing volumes occurs automatically, successfully washing out the metabolic CO2 and maintaining a nearly normal level of CO2 in arterial blood (even during exercise when the internal metabolic production of CO2 is increased).
Acute breathing difficulty during swimming or diving may be associated with Immersion Pulmonary Edema (IPE). At SPUMS 2014, Peter Wilmshurst presented a summary of his rich clinical experience. In his opinion, IPE is an underestimated cause of fatalities. Problem with diagnosis of IPE in scuba diving is its rapid evolution. Divers may be overwhelmed with an internal lung flood before they realize the nature of their breathing difficulty and can safely exit the water.
At the 43rd Annual Scientific Meeting of South Pacific Underwater Medical Society going on May 18 – 25, 2014, a key theme is PFO and diving. The keynote speaker is Dr. Peter Wilmshurst, the cardiologist and diving physician who first described the association between PFO and decompression sickness in 1986. Here, he presented his findings in several hundred cases of DCS. His insight into this problem is most valuable and we are looking forward to the publication of a synthesis of his findings.
Deep vein thrombosis (DVT) is a condition in which a blood clot (thrombus) forms in one or more of the deep veins, usually in the legs. Blood clots can break free and travel with blood causing life-threatening condition like pulmonary embolism (PE) or a stroke due to paradoxical embolism in people with patent foramen ovale (PFO). DVT is not related to diving, but divers often travel and thus are exposed to risk of DVT. In case of acute DVT, divers must not dive.
Crowdsourcing is a means to raise funds through public contributions in a manner which allows a large number of small contributions to make a difference. Originally started in technology areas where considerable upfront capital was required to make the project viable, SciFund and Experiment.com have taken this into the research arena to allow small research projects to gain support. As those in research know, it is notoriously difficult to raise funds for small research projects and crowdsourcing provides that opportunity. As an example of how well it can work, Experiment has raised $600,000 over the last 4 years.
Heart disease is the leading cause of death in women and heart attack is the leading cause of hospitalization. The characteristics of this disease in women may differ from those known in men; the age of onset, presence of risk factors, probability of aggressive diagnosis and treatment vary in men and women.
For example, heart disease develops 7 to 10 years later in women than in men (potentially because of a protective effect of estrogen). Heart attack (myocardial infarction, MI) is less frequent in young women than in men, but young women with heart attack are at greater risk of dying within 28 days of the attack. Common risk factors for heart disease have similar predicting value both for men and women; however, men more frequently have smoking as risk a factor, whereas women more frequently have hypertension, diabetes, hypercholesterolemia and angina. Although women typically smoke less, the relative risk for MI of women who smoke was 1.5 to 2 times greater than of men who smoked, especially in younger age (< 55 years). Higher prevalence of diabetes contributes to higher mortality rates of MI among women.
Generally, habitual physical activity reduces risk of death due to heart disease, but in susceptible persons vigorous activity can increase the risk of sudden cardiac death and acute myocardial infarction. Susceptible adult individuals are primarily those with atherosclerotic disease.
The incidence of both acute myocardial infarction and sudden death is greatest in habitually sedentary individuals. Habitually sedentary men are 56 times more likely to experience cardiac death during or after vigorous exercise than while resting; however, very physically active men are only five times more likely to die during or after vigorous exercise than at rest.2 Similarly acute myocardial infarction during or soon after vigorous physical exertion is 50 times more likely in least active than in most active subjects.3
Maintaining physical fitness through regular physical activity may help to reduce premature death because a disproportionate number of fatal cardiac events occur in the least physically active subjects performing unaccustomed physical activity. While sedentary people are advised to change their lifestyle and adopt regular physical exercise starting with low intensity and gradually increasing over time, they may need a preparticipation screening. Subjects with any health limitations need medical clearing and preferably a professional fitness coach. High-risk patients should be excluded from certain activities. For a brief set of guidelines, read “When to consult a health-care provider before engaging in physical activities.”
Even the most restrictive policies will never be able to completely prevent cardiovascular events associated with exercise. For individuals who exercise, it is important to recognize and report prodromal symptoms (symptoms preceding cardiac event). Prodromal symptoms were present in 50% of joggers, 75% of squash players, and 81% of distance runners who died during exercise. Prodromal symptoms may include chest pain/angina, increasing fatigue, indigestion/heartburn/gastrointestinal symptoms, excessive breathlessness, ear or neck pain, vague malaise, upper respiratory tract infection, dizziness/palpitations or severe headache. People who exercise have to be aware of this and physicians should inquire about exercise and these symptoms during exams.
For more details about risk/benefit and strategies to mitigate risks see the paper of Thompson PD et al.
Thompson PD et al. Scientific Statement From the American Heart Association Council on Nutrition, Physical Exercise and Acute Cardiovascular Events: Placing the Risks Into Perspective: Physical Activity, and Metabolism and the Council on Clinical Cardiology.Circulation. 2007;115:2358-2368; originally published online April 27, 2007; http://circ.ahajournals.org/content/115/17/2358
Siscovick DS, Weiss NS, Fletcher RH, Lasky T. The incidence of primary cardiac arrest during vigorous exercise. N Engl J Med. 1984;311: 874–877.
Mittleman MA, Maclure M, Tofler GH, Sherwood JB, Goldberg RJ, Muller JE. Triggering of acute myocardial infarction by heavy physical exertion: protection against triggering by regular exertion: Determinants of Myocardial Infarction Onset Study Investigators. N Engl J Med. 1993;329:1677–1683.
The Multi-Ethnic Study of Atherosclerosis (MESA) included 6,229 US adults aged 44 to 84. All patients were given one point for each of four behaviors they had option to follow: a Mediterranean-style diet, 150 minutes of moderate-intensity physical activity per week, maintaining a healthy body-mass index (BMI), and not smoking. All participants also underwent coronary artery calcium screening at baseline and three years later.
People with higher score (healthier lifestyle) had slower progression of atherosclerosis and 80% less risk of death in the observed period. Each of the healthy behaviors contributed independently to better outcome.
Of the behaviors investigated, however, smoking was the most devastating. Subjects who exercised, ate healthily and maintained normal weight, but smoked, were still worse off than people who did nothing else right but stayed away from cigarettes. Not smoking is the best individual thing people (including scuba divers) can do for their health.
Read full paper: Ahmed HM, Blaha MJ, Nasir K, et al. Low-risk lifestyle, coronary calcium, cardiovascular events, and mortality: results from MESA. Am J Epidemiol 2013; DOI:10.1093/aje/kws453. Available at: http://aje.oxfordjournals.org.