SAFETY continued
prudent to continue or “called” the dive, the fatal situation may have been averted. With an aging active diving population (the average age of injured recreational divers being somewhere between 40 and 50), diseases associated with age are likely to be an issue. When you look at sports-related deaths, coronary artery
immersion and constriction of peripheral blood vessels, an increased physical workload due to the resistance of water and the increased work of breathing through the regulator. When you add additional exertion caused by swimming against a current, wave action or simply working hard to compensate for poor buoyancy, the risk of a dive-provoked cardiac event may be signifi- cantly increased. This risk can be exacerbated by emotional stress brought on by diving in an unfamiliar location, having been away from diving for an extended period or diving beyond one’s limits. Divers who are aware of the conditions that contribute to arrhythmias may be able to mitigate these risks associated with immersion. For example, the risks associated with exposure to cold can be mitigated by having the appropriate exposure protection whether it be wetsuits, drysuits or even diveskins. For those diving in extreme coldwater conditions, heated undergarments and heated gloves are available. For the risks associated with increased workload, divers can mitigate those risks by having a properly tuned regulator and reducing drag in the water by becoming more streamlined and improving their buoyancy control.
disease is the leading cause of sudden cardiac death in those over the age of 35. The risk of cardiac-related death in divers
Cardiac events now rank the second leading cause of death in scuba divers behind drowning.
steadily increases with age with divers older than 50 having a risk 12.9 times that of younger divers. From the DAN data, 25% of the divers who suffered a cardiac event while diving were completely asymptomatic and were totally unaware of their condition. It is estimated that over 3 million Americans and approximately 2.8 million Europeans will scuba dive each year. While recre- ational diving fatalities are rare (averaging 82 worldwide) the number involving cardiac-related issues is on the increase. From 1989 to 2015, the proportion of diving fatalities involving those from the 50–59-year-old age group increased from 15% to 35%, while fatalities in the over-60s increased significantly from 5% to 20%. Cardiac events now rank the second leading cause of death in scuba divers behind drown- ing. We know that diving exposes divers' bodies to various stressors that independently affect cardiovascular function that may initiate an irregular heartbeat called an arrhythmia. These stressors include immersion, exposure to cold, and in- creased workload while diving. The combined effect of these factors is that the volume of blood in the vessels of the chest and heart increases significantly, stretching the walls of the heart and major vessels. While there is nothing we can do to mitigate the stressor of immersion, with some degree of fore- thought and preparation, we may be able to mitigate the po- tential for an arrhythmia by managing the other stressors. With immersion, blood pressure slightly increases, and the heart has to work harder to maintain circulation. These con- ditions contribute to various changes in heart rhythm (ar- rhythmias) that range from a slow heart rate (bradycardia) caused by cold, to fast heart rate (tachyarrhythmia) caused by the body’s response to stress. Older divers, especially those with cardiovascular disease, are at greater risk of adverse reactions to these stresses. It is vital that divers be aware of the effects of immersion on the cardiovascular system while scuba diving. There is also an increased strain on the heart due to
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