CHILDREN AND DIVING
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From: The Professional Association of Diving Instructors,
THE UNDERSEA JOURNAL ? FIRST QUARTER 2001
Are children more susceptible to oxygen toxicity?
Clinical experience here at Duke shows no particular difference in susceptibility of children down to age 8 to either pulmonary or CNS oxygen toxicity. Only a single paper was found which attempted to address the subject (Bland RD. American review of Respiratory Disease. 122(5 pt 2) 45?54, 1980). They were only able to cite animal data that showed that the effect of age on susceptibility to pulmonary oxygen toxicity was species specific, in some immaturity was protective, in others it was not.
[The recreational dive community regards a PP02 of 1.4 bar as a conservative figure when discussing the possible onset of acute oxygen toxicity. PADI has not approved 10 and 11 year?old children for enriched air nitrox, technical or deep diving courses. So, given that children will breathe compressed air only, they would need to dive to 60 metres/195 feet before reaching a PP02 of 1.4 bar. Again, given the 12 metre/40 foot limit, this is an incredibly generous safety margin. Pulmonary oxygen toxicity is a concern for those breathing elevated PP02 over time and is not relevant to this discussion.]
Are growing bones more susceptible to injury from decompression sickness or silent bubbles?
In growing children up to the age of 18, bones continue to grow from a region called the physis which, in long bones (arms and legs), is near each end. This area consists of mostly cartilage and has no blood supply, it depends on diffusion of substances to and from adjacent tissue, which has a blood supply. If this area is injured then abnormal bone growth will result, such as one leg being longer than the other. The main causes of injury to this region are weight bearing sports activities such as skiing, rollerblading, ice?skating, football, etc. Accidental fractures are also common causes of injury to the physis.
Joints are affected in musculoskeletal decompression sickness and osteonecrosis has been associated with divers who have done many near saturation dives, such as tunnel workers. We do not know the exact anatomical site of joint involvement and there is no published evidence suggesting that the physis is more susceptible to decompression sickness in children compared to adults. Children are unlikely to be exposed to the conditions most often associated with osteonecrosis in adults, but sport divers do occasionally develop osteonecrosis. Thus, we support time and depth restrictions for children. Restrictions have been imposed by organizations such as SSI, PADI and CMAS for children in confined and open water environments.
[Limiting 10? and I I ?year?old children to a maximum depth of 12 metres/40 feet avoids this issue almost entirely. It's worth mentioning that, given its poor blood supply, the physis is a "slow" tissue (it "on gasses" and "off gasses" slowly). Slow tissues are more of a factor on longer duration dives where there is plenty of time for tissues with poor blood supply to absorb nitrogen. Hence the enhanced osteonecrosis concerns for caisson workers and saturation divers who spend a good deal of time under significant pressure. Given the depth restrictions and the relatively short bottom times imposed on 10 and 11 year?olds, and the fact that scuba diving is a non?impact activity, risks to the physis can be considered minimal.]
Is there any difference in the lung tissue or chest wall, which might make children more susceptible to pulmonary barotrauma?
Up to about age 8 the pulmonary alveoli are still multiplying, pulmonary elasticity is decreased, and chest wall compliance increased. This puts children 8 and younger at a theoretical increased risk of pulmonary barotrauma, although we have found nothing published in the literature addressing this possibility. Based on this consideration, CMAS, PADI, SDI and SSI have recommend that children younger than age 8 not scuba dive and we concur. Given the variation in rates of growth and maturity it would even seem prudent to raise the minimum age to closer to puberty (not less than 10 years old) to exclude any chance of children with immature lungs from diving. Organizations including SSI, SDI and PADI have all agreed.
[This is, quite simply, the primary reason for the 10 year-old limit.]
Are children more likely to have an asthmatic attack while diving?
Risk factors that might provoke an asthmatic attack such as cold or exercise are present in the dry environment as well as underwater. However, the possibility of salt?water aspiration adds an additional risk factor. In addition, a child's reaction to an asthmatic attack underwater may involve a higher panic component than in an adult, putting them at increased of injury. Unfortunately there is no controlled study data to accept or refute these hypotheses.
[Active asthma is a contraindication to diving, for both adults and children. This is a determination made by doctors and parents for 10 and 11 year?olds. If a 10 or 11 year?old child, has active asthma, or if there is any doubt at all, the only possible recommendation is to avoid diving completely. This goes for older children and adults, too.]
Do children have an increased propensity for ear barotrauma?
Up to age 8, the Eustachian tube, which is responsible for equalizing the middle ear, is more tortuous compared to adults. This is why ear infections are more common in children than adults. Dr.Guy Vandenhoven reported on his experience with 234 children, ages 6?12, in a Belgian Diving club (personal communication) from 1985?1992 and found barotrauma and ear infections to be the most common medical sequelae to diving.
[This is another reason for PADI's 10 year?old limit. And a very good reason to make sure that you, as a PADI Professional, ensure everyone in your dive training programs can equalize properly. I don't need to elaborate on that here, but it's worth pointing out that equalization of ears and mask is one of the first and most important skills any diver needs to master.]
Are there special considerations needed to determine whether thermal protection is adequate?
Children have a higher surface area/volume ratio and smaller body mass, which means under similar conditions with similar thermal protection they will cool faster. Special attention must be paid to ensure that children do not become hypothermic during diving. Exposure protection designed for children's sizes is recommended where warranted.
[Make sure children have adequate thermal protection and monitor them closely for signs of chilling.]
Do children have a higher propensity to form venous gas emboli (VGE) than adults?
No studies have been done comparing post dive VGE incidence in children compared to adults. Are children more susceptible to decompression sickness than adults? There are no published data that could be used to answer this question. However, organizations including PADI, SSI and SDI have all imposed depth and time restrictions to address this.
If children do get decompression sickness, is it likely to be of increased severity compared to adults?
There is no published data, which could be used to answer this question.
Do children have the strength and endurance to cope with emergencies?
Children have less strength and endurance than adults. Whether it is sufficient to cope with emergencies, swim against currents, or board a boat under less than ideal conditions is unknown since the appropriate human factor studies have not been carried out.
[This is not unique to 10 and 11 year old children. PADI Professionals have helped divers deal with this issue for years. Specific to this age group however, is the requirement that they dive with a parent, guardian or PADI Professional within the 12 metre/40 foot limit. PADI is defining the envelope within which these children may dive. You must further define it based on local conditions. Philosophically, the very premise of the PADI Rescue Diver course reflects this issue in that there is never only one way to deal with an emergency or stressful situation. Addressing this concern from a practical perspective begins way back with dive site selection: Make sure the site is appropriate for divers' age and experience levels. It is not reasonable or prudent to expect children to simply tag along on dive trips designed for experienced adults. Emphasize the importance of dive planning and sticking to the plan. Ensure adequate supervision, etc. (You know what I mean, you do it every day). That said, there are numerous instances of children younger than 10 making emergency assistance calls and helping adults in distress in other ways. Who's to say, for example, that a 10 year?old couldn't help by offering an alternate air source?]
Summary
Based on the above considerations the only data available that could be used to establish a minimum age for diving are based on pulmonary development. This suggests the possibility of and increased susceptibility to pulmonary barotrauma for pre?pubertal children, especially those less than 10 years old. There is no other data available that would assist in making this determination. It should also be noted that the empirical data and collective experience with children scuba diving seems to be based on shallow water, protected diving.
There is insufficient information available to make any evidence?based medical judgment for or against involving children in scuba diving. As more children under the age of 12 dive, additional empirical data will gradually accumulate. However, in order for these data to be useful in making medically based decisions regarding children in diving it will have to be carefully collected, vetted, and analyzed.
While the above represents the fruit of DAN's best effort at looking at the problem we realize there may be quality data available that has not yet been published. For as wide a perspective as possible we are inviting anyone with substantive comments either on DAN's assessment of the issues pertinent to children in diving in general to forward them to DAN. We realize that this issue will generate a lot of personal opinions, and while these are useful, conclusions backed up by actual data or records are the most constructive.
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