health

Mobile Medical Applications: Is Apple Leading the Pack or Catching Up?

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.

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High-Fat Diet and Risk of Decompression Illness

dietObesity has been long considered a risk factor for decompression sickness (DCS). It has been based on findings in animal studies and epidemiological data in military diving. There was no data to confirm the same effects of obesity on incidence of DCS in recreational diving; however, there were some studies indicating a positive correlation between body mass index (BMI) and likelihood of venous gas emboli (circulating gas bubbles) after dive.

In a recent paper, Kaczerska D, et al. The influence of high-fat diets on the occurrence of decompression stress after air dives. UHM 2013;40(6):487-497, intended to test possible effects of high fat intake on risk of DCS.

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Heart Attack Symptoms in Women

ImageHeart 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.

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Medicinal nicotine and diving

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Smoking has been recognized as a major health problem, which decreases physical fitness and increases risk of serious illness and premature death.  The surgeon general’s “Smoking and Health” report released in 1964  launched the anti-smoking campaign in United States. Back then, 42 percent of adult population smoked in comparison to today’s 18 percent. The government set the goal to reduce this to about 12 percent of the adult population by 2020. While the public awareness is there, individuals still struggle with the habit mostly due to the addictive nature of nicotine. Smoking is less prevalent among divers, but it is still a problem because its acute and chronic effects may contribute to scuba diving fatalities.

(Learn more about the current state of smoking in America, with this PBS NewsHour Interview with Acting Surgeon General Boris Lushniak)

Acute effects of  smoking

Nicotine affects the body in many ways. It increases blood pressure and heart rate frequency. The mechanism of blood pressure and heart rate elevation by nicotine occurs via activation of the sympathetic nervous system with release of norepinephrine and epinephrine (adrenaline).  Cigarette smoking results in sympathetic neural arousal that lasts for 24 hours. This is reflected in a loss of natural heart rate variability and an increased risk of arrhythmia. Narrowing of blood vessels requires the heart to work harder and use more oxygen, while the simultaneous narrowing of the coronary arteries diminishes the blood and oxygen supply to the heart muscle, which can contribute to myocardial infarction. Carbon monoxide reduces availability of oxygen in blood and may exaggerate hypoxia of heart muscles. Nicotine also induces endothelial dysfunction and increased tendency to clotting. Besides that, cigarette smoke contains many toxins other than nicotine (for example, carbon monoxide and oxidant gases) that might contribute to cardiovascular toxicity. Chronic smoking contributes to development of atherosclerosis, heart disease, cancer and premature death.

Major health damage related to smoking is caused by various components of the smoke, but nicotine has its own adverse effects. In an attempt to reduce risks while satisfying the cravings for nicotine, several products that deliver nicotine without smoke have been brought to the market. They are in form of skin patches, nasal spray, chewing gums and inhalers. The most recent, the e-cigarette,  is generating a lot of public discussion. It is important to note that while administering nicotine without smoke may reduce health damage caused by smoke components, it does not reduce effects of nicotine.

Divers are encouraged to cease smoking. Any effective help is welcomed. Medicinal nicotine may be the way to go for those who have failed in their previous attempts, but medical supervision is advised. Some means of delivery of medicinal nicotine, like chewing gums, nasal sprays, dermal patches and inhalers have been approved or tolerated by FDA which summarizes mainstream medical judgement. However some methods raise concerns about propagating the addiction, such as the more elaborate deliveries like the e-cigarette. Divers on a cessation program using medicinal nicotine must be aware of the side effects of nicotine use, nicotine overdose and nicotine withdrawal symptoms.

Side effects

Adverse effects of medicinal nicotine depend on dose and method of administration. Using nicotine inhalers  may cause local irritation in mouth and throat, coughing and rhinitis, change of taste, pain in jaw and neck, tooth disorders and sinusitis. Lozenge and chewing gums may cause dyspepsia. Other adverse events occurring in greater than 3% of patients on active drug include nausea, headache, influenza-like symptoms, pain, back pain, allergy, paresthesia, flatulence and fever.

Nicotine overdose

The overdose of nicotine among adult smokers is not very likely; however, a person can overdose on nicotine through a combination of nicotine patches, nicotine gum, nicotine inhaler cartridges and/or tobacco smoking at the same time. Intoxications with nicotine have been reported and causes include ingestion of nicotine pharmaceuticals, tobacco products, and prolonged skin contacts with nicotine containing plants or accidental ingestion of pesticides containing nicotine. The initial symptoms are caused by stimulatory effects and include nausea and vomiting, excessive salivation, abdominal pain, pallor, sweating, hypertension, tachycardia, ataxia, tremor, headache, dizziness, muscle twitching, and seizures. This may be later followed by depressor effects including low blood pressure and slow heart rate, central nervous system depression, coma, muscular weakness and/or paralysis, with difficulty breathing or respiratory failure.

Withdrawal

Symptoms of withdrawal may occur early on in the smoking cessation process and while on medicinal nicotine. Common withdrawal symptoms include dizziness, anxiety, sleep disorder, depression, drug dependence, fatigue and myalgia.

Diving and medicinal nicotine

Divers are encouraged to quit smoking using any possible help they need with due medical supervision. However, use of medicinal nicotine as a convenient replacement or addition to smoking may be unsafe and is not advised. While on a cessation program, divers must be aware of potential adverse effects which may be confused for dive related symptoms. As with all  medical interventions, it is wise to abstain from diving for a while to weather out possible adverse events and their interaction with dive safety.

Post written by: Petar Denoble, MD, D.Sc.

Obesity, The Heart & Diving

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How does obesity affect your heart and why can obese divers develop heart trouble at apparently low level of exertion?

Obesity is an escalating problem and is linked to a spectrum of cardiac dysfunctions that affect feeling of wellbeing, physical fitness and longevity. In a recent review paper Rider O.J. et al, summarize current knowledge about how obesity affects the heart. The most notable fact is the change of source of the fuel from which the heart derives its energy. By excluding glucose and relying mostly on fatty acids, the energy process becomes less efficient and the heart needs more oxygen for the same level of work. In the long run, lipids become toxic for heart cells and lead to structural changes and weakening of the heart muscles, which is disabling and life threatening. In case of divers who feel fit enough to dive, however, the danger comes from the increased needs of heart for oxygen even at rest. In some cases, even a small increase in exercise level may cause a significant hypoxia of heart muscles which can lead to major troubles.

The good thing is that the problem can be improved by moderate weight loss. However, weight regulation should be started sooner rather than later when changes may become irreversible.

Read the full paper: OJ Rider, P Cox, D Tyler, K Clarke and S Neubauer. Myocardial substrate metabolism in obesity. International Journal of Obesity (2013) 37, 972–979; doi:10.1038/ijo.2012.170; published online 16 October 2012

Learn more from DAN FAQs: Healthy But Overweight

Post written by: Petar Denoble, MD, D.Sc.

Four Healthy Lifestyle Behaviors Slow Down Progression of Atherosclerosis and Lower Risk of Death

Gabriella FabbriThe 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.

Learn more about cardiovascular health.

Post written by: Petar Denoble, MD, D.Sc.

DAN Investigates Implanted Cardiac Devices: Volunteers Needed

ImageIn a recent divers’ health survey that DAN conducted, 25 participants, or one in 200, reported having an implanted pacemaker device. The median age of divers with implanted devices was 64 (39 to 90) years and 95% were male. We did not anticipate this and the survey did not ask about reasons for pacemaker implants, but we have learned something about their health status.

  • About 64% active divers with pacemakers were either overweight or obese.
  • 22 reported that they regularly participate in vigorous exercise such as running, biking, swimming, weightlifting, etc.
  • Half were diagnosed with hypercholesterolemia, 9 with hypertension and 4 with diabetes.
  •  Few still indulge in some high risk habits such as heavy drinking and tobacco smoking.
  • When asked to describe their general health, one participant answered it was excellent, 12 very good, 10 good, and one diver said that his health was fair or poor.

Five of the respondents with implanted pacemakers had basic certifications, 16 had advanced and four held instructor-level diving certifications. In terms of diving habits, the respondents with implanted pacemakers reported they:

  • Perform about 30 dives per year (median)
  • Have been active divers for an average of 20 years
  • Have logged a median of 460 total lifetime dives per diver.

Divers with pacemakers don’t seem to be less active than other divers, but we did not explore the circumstances and severity of their dives. We did not ask about specific symptoms or manifestations related to underlying conditions for which they received the pacemaker nor about possible unwanted side effects of pacemakers.

 Volunteers with Pacemakers Needed

This is why DAN designed a new study to learn about specific issues experienced by divers with pacemakers choosing to dive with or without medical clearance. DAN is looking for volunteers to participate in the “Diving Experience of Divers with Implanted Cardiac Devices” study, which consists of an online survey that takes approximately 10 minutes to complete, in addition to a possible follow-up interview if clarification is needed. If you would like to participate in this investigative study, ongoing through August* 2013, please contact DAN Research (919-684-2948 or research@dan.org). Participants will not be compensated for participation.

Post written by: Petar Denoble, MD, D.Sc.

*NOTE: This study has been extended through November 2013.