A team of top researchers and leaders of the Divers Alert Network (DAN) addressed the demands of public safety diving during the recent DEMA show in Las Vegas. DEMA is an organization dedicated to the business side of diving. DAN’s President and Director of Training, Dan Orr, pointed out that diving accidents could cause injuries and losses that might be irreversible. Yet, most diving accidents could have been prevented.
Diving involves nature’s conditions, physiology, physics and technology, any of which could cause such problems as running out of breathing gas, entrapment, equipment failures, rough water conditions, injury, buoyancy problems, inappropriate breathing gas, and health conditions that impair a diver’s abilities. But the human element in diving also unwittingly—or deliberately—puts aside known procedures and safety measures, creating mistakes and crises that could have been avoided, Orr said.
Diving involves what might appear to be “routine” procedures, but which, in fact, are vital to diver safety, said Orr. Such things as avoiding peer pressure, configuring diving gear on the dock rather than aboard the boat where rough water might reign, knowing how to deploy or share an air supply to another diver without losing one’s own supply, being able to operate the dive gear octopus in any conditions, knowing how to ditch weights in one motion, doing pre-dive equipment checks for self and buddy, achieving correct buoyancy, and setting a communications system are all things good divers know, but they must be practiced regularly, said Orr.
“Consider the risks and your diving ability,” he said. “Practice basic and emergency skills regularly. Stay within your ability.” He added that there should always be a method to “call the dive, at any time, for any reason, no argument,” because safety must be paramount.
Statistics show that the diving population is actually getting older—perhaps due to the time and money older individuals might have for sport diving, and the fact that people live longer these days, have better medicine and controls for chronic conditions, and stay with the sport because it is appealing. But the trend seems true for public safety divers, too, who have usually been at diving work longer, developing the specialized skills needed for rescue and recovery.
Age can be a factor in safe diving, said Neal Pollock, Ph.D., DAN Research Director and Research Associate at the Center for Hyperbaric Medicine and Environmental Physiology of the Duke University Medical Center, because divers need physical ability, emotional maturity and intellectual ability to be safe divers. They must master a reasonable knowledge base, recognize and manage visible and invisible hazards, think clearly and act effectively when under the stress that an underwater emergency can create. There is certainly no upper limit for a diver’s age, but a safe diver needs the individual capacity and health to avoid compromising safety.
Aerobic capacity, learning and retention, processing ability, and flexibility in the brain’s functions are important to safe diving. Dr. Pollock said, “You need strength and endurance to dive.” A fitness strategy means doing regular exercise. “Use it or lose it!” he warned. For example, good pulmonary function can be promoted by regular exercise.
Diving’s positive effects involve a physical prowess that encourages a diver to get fit and stay fit, and to keep to a plan of sound nutrition. Diving also has an intellectual component that stimulates continued learning and critical thinking skills. And it has an emotional element that motivates individuals to be engaged in both self-appraisal and group interaction to assure safety and fitness among divers and their teams.
Physical health is important. Chronic disease such as hypertension, heart disease, and diabetes (or pre-diabetes) can be risk factors to safe diving, said Pollock. Immersing the body in water sends blood to the heart and that could adversely affect a diver whose physical health is such that the stress of immersion, the demands of buoyancy, the stress of cold water, or the weight of dive gear create a danger.
Pollock recommends working with one’s physician, preferably one familiar with the demands of diving, to maintain a health level that tolerates the tasks and hazards associated with diving. For example, managing glucose levels on the day of the dive, or knowing what effects various medicines have for divers is vital to health and safety.
Because older individuals tend to have a higher mean skin temperature, an equipment change might be needed for the diver who feels more discomfort in colder water or whose physical ability is affected by cold water. Public safety divers cannot usually choose their venue, so cold water may be the rule, but a warmer wet suit or drysuit can help. Despite it popular use, neoprene actually responds poorly to pressure. Neoprene compresses, reduces insulation and alters the suit’s fit.
In fact, the space between the suit and the body actually increases as the suit compresses. Good ankle, wrist and neck seals will help—for a while. A dry suit reduces heat loss, but the diver needs wicking fabric next to the skin to reduce loss of body heat due to evaporation and conduction. Use synthetic, not cotton, material next to the skin to wick away moisture.
Suits that feature a type of in-suit heating may be warm, but they can also create a potential decompression hazard because, if the power is lost, the diver gets cold quickly and might hasten ascent without proper rest stops. Age-related vision changes can be remedied by such means as surgical correction, gas permeable lenses, or a vision-corrected mask.
Public safety and commercial divers may have threshold shifts in their ability to equalize mid-ear pressure. The inability to equalize effectively can stress the ear structures, said Pollock, and such stresses could result in transient or even permanent damage. Use the lowest stress equalizing technique that does the job, and that can be done gently and often and early in the dive, he said.
“Use the method that works for you, not someone else.” Deal with ear infections immediately because some viruses can drop hearing ability 30 to 40 percent and cause permanent damage if not cleared within 72 hours, he said. Also, hearing damage from noise can occur in some public safety and commercial diving. “Avoid extreme noise exposure,” Pollock recommended. And, because much public safety diving occurs in contaminated water, wear isolation gear, he said, and wear a helmet to avoid contamination of the head.
Replacement joints and orthopedic problems may influence the selection, wearing, transporting, and donning/doffing of diving equipment. Again, judgment must be used to determine whether such replacements will compromise safety. Pacemakers and stents may be compatible with diving after the patient has fully recovered, but such evaluations must be done on a case-by-case basis. “You have to do your homework” with your physician, Pollock said.
Gradient factors may have to be adjusted by the older diver. Maximum allowable pressure should be set at 30/70, Pollock recommended. “Keep the ascent profile lower,” so that individual needs and tolerances can be met. Dive computers can be reliable and flexible, but they might give a “false sense of security,” he said.
“Build in a safety margin and, as you age, build in more.” He added that weights should be able to be ditched in one effort to release all the weights. Putting weights in back pockets or where they cannot be easily ditched will affect a diver’s control. “Dive smarter; not harder,” Pollock said.
Medications can have positive effects on health, but they also may require different considerations from divers. “The action of medicine under hyperbaric conditions is largely untested,” said Pollock. Interaction hazards can be magnified by multiple medicines. Consult with a physician about such effects and whether diving safety will be compromised. Even seemingly innocuous drugs such as “baby aspirin” or blood thinners may pose a hazard in diving because diving subjects its participants to bumps and bangs.
Petar Denoble, M.D., D. Sc., is the Senior Research Director of DAN Medical Research. He specializes in studies in open circuit, closed circuit, deep bounce and saturation diving. He said oxygen can be toxic at high pressure and individual susceptibility to such toxicity can vary, but most persons affected by oxygen toxicity will exhibit central nervous system disturbances including seizures, ocular hyperbaric induced myopia that can last weeks, and pulmonary problems. All are dose-dependent.
Symptoms might include lip twitching, nausea, vertigo, respiratory disturbances, body twitching, a felling of drowsiness, numbness, confusion, visual disturbances, acoustic hallucinations, and parathaesia. Although some of these symptoms might seem harmless, they could be fatal such as a seizure that makes the diver drop the mouthpiece or make an inappropriate ascent. Dr. Denoble recommended a mouthpiece holder or full facemask for extra safety.
Those most at risk for oxygen toxicity are close circuit oxygen divers, nitrox divers, mixed gas open circuit, or those who have been treated with hyperbaric oxygen, but case-by-case variations can occur.
Some prescription and over-the-counter drugs can have adverse effects on a diver. Cialis®, Viagra®, Sudafed®, Aleve®, statins, antihistamines, decongestants, and antidepressants can remain potent in the body for hours to even days, and may have side or after effects that cause restlessness, nausea, vomiting, headache, drowsiness, nervousness, dizziness, difficulty sleeping, stomach pain, dry membranes, difficulty breathing, slowing of coordination, slow judgment, irregular heartbeat, hypertension, imbalance, vasodilatation, some increases in blood pressure, myocardial infarction and arrhythmia.
Dr. Denoble advised asking one’s physician about side effects and their possible exacerbation in diving or in going to greater depths than ordinary. And such drugs may actually lower an individual’s threshold for oxygen toxicity.
Ear and sinus problems plague some divers. Martin McCafferty, EMT-P, DMT, EMD-A, is a Medical Information Specialist for DAN. He said about 40 percent of the inquiries DAN receives about diver health tend to involve questions about ears and sinuses, including motion sickness while traveling by boat to and from a diving area. DAN has an Emergency Hotline phone number of (919) 684-9111.
He explained that the ear has is actually an outer ear and ear canal, middle ear (also the Eustachian tubes), and inner ear (and auditory nerves), any of which can be affected by diving. The frontal sinuses above the eyebrows, (which tend to be the most problematic), sinuses near the cheekbones, behind the eyes, and toward the back of the head can be affected by diving. An active cold, congestion or allergy can exacerbate diver’s ear and sinus problems, he said. Symptoms can include dizziness, uncoordinated gait, a sense of spinning, vomiting, congestion, or pain behind the eyes.
Middle ear problems usually involve feeling a fullness or “water” in the ear (not in the ear canal), muffled hearing, dizziness, lightheadedness, tinnitus, discomfort, hearing pops or cracks on yawning as the air moves, acute pain, hearing loss, feeling off balance, or having blood in the sputum. Sinus problems are usually marked by pressure in the sinuses, lightheadedness, dizziness, localized headache, pain at the forehead/cheeks/upper teeth/occipital area/behind the eyes; severe dizziness, numb cheeks/teeth/gum line, or bloody nose or blood in the mask.
Learning the right technique for equalizing is important, said McCafferty, and the technique that works for one person might not work for another. All sinuses need to equalize at the same time with the ears. The openings to the sinuses are small so mucus or congestion can interfere when trying to equalize. “If you’re feeling increased pressure, equalize literally every two feet!” he said, adding that repeatedly equalizing on the way to the dive site, pushing the lower jaw forward to loosen the muscles to open the Eustachian tubes, and other techniques can help the process of equalizing.
Stephenie Slahor, Ph.D., J.D., writes in the fields of law enforcement and security. She can be reached at email@example.com. Photos courtesy of Dive Rescue International.