Diving Doctor – Doctor Oliver looks at the DAN report in the April issue of Sportdiver

The most recent DAN report 2008 makes sober, useful reading. The report is free to all and is a remarkable service to the whole diving community. The report can be obtained by email from the DAN web site


While the report came out in 2008, and relates mostly to 2006, the main points are still very much up to date. There are sections on Project Dive Exploration, diving injuries, diving fatalities and breath holding incidents. The introduction highlights the diver’s responsibility for the maintenance of their medical, physical and psychological fitness, but I would recommend it as reading for anyone responsible for looking after divers. At a personal health level, perhaps stopping smoking and regular blood pressure checks are most important areas to concentrate on. After allergy, high blood pressure was the most common chronic medical condition, at 7 % of 1081 Project Dive Exploration divers. High blood pressure is the single most important factor in causing heart disease leading to heart attacks and, while we all feel like this will not happen to us, 90,000 people die of a heart attack every year in the UK. This makes it the biggest single killer.

Unfortunately, high blood pressure and heart disease do not have symptoms until late in the process, hence the need for your GP to check for it. In the absence of any other medical problems, a yearly blood pressure check from 40yrs in men and 50 yrs in women would be reasonable. The goal is a blood pressure of no more than 140/90. The top number is the pressure when the heart is contracting and should be no more than 140mmHg, and the bottom number is the pressure when the heart is relaxed and should be no more than 90mmHg, but multiple checks are useful to confirm the results.

Explanations for the cause of high blood pressure are not always clear, but these are common associations:

Overweight or obese

Not enough physical exercise

Too much salt or fat in your diet

Drinking too much alcohol


Insufficient fruit and vegetables

Diabetes Mellitus

Family history of high blood pressure.

The most healthy option is to tackle these associations before medications are used.

To characterize some of these effects in a standard fashion, quickly, simply and with minimal equipment, the much debated measure of body composition, body mass index (BMI) is commonly used. The result is obtained by dividing weight in kilograms by height in meters squared (kg/m2, normal=18.5 to 24.9) Divers tend to hate this measure as there are problems with its use, but the report outlines the waist to hip ratio as a predictor of its usefulness. Divide the circumference of your hips at the narrowest point, by the circumference at the widest point in centimeters or inches. The result should be less than 0.8 in men and 0.7 in women if BMI is a good guide to your body composition. Neither of these measures give a complete picture, but are useful screening tools and give a guide to personal trends overtime.

Despite the debates, the DAN report is clear that, in recent years people with a high BMI are commonly involved in diving incidents and where medical history was available, 38% of fatalities had heart disease and 11% had high blood pressure. These are clearly important health issues for us all.

Read the May issue of Sportdiver for Doctor Oliver’s next article.