Friday, 19 March 2004 00:00

Children & Diving

By Dr Simon Mitchell

For some years now PADI has offered a 'Junior Open Water Diver' program for children aged 12 - 15 years. Graduates of this course are certified to dive in open water under the direct supervision of a qualified adult diver. More recently PADI has introduced its 'Bubblemaker' program. This program is provided for children aged 8 - 11 years and offers the opportunity to try scuba in confined water less than 2 metres under the direct supervision of an Assistant Instructor or above.

Part 1

It was perhaps predictable that this attempt to introduce diving to younger persons would result in expressions of concern about safety from various quarters, including members of the medical community. Unfortunately, in the absence of published data describing the safety of diving in children, much of the commentary on this issue is based on speculation and emotion. Under these circumstances it is easy for discussants on both sides to lose perspective, and the debate may not necessarily generate the right answers. As both a diving physician and an experienced diving instructor I am well positioned to simultaneously appreciate both supportive and cynical views on children in diving. It follows that in this article I will review what is known (and not known) about the safety of diving for children, and present my own views on the issue.

Many of the basic rules and considerations that determine the appropriateness of diving for any candidate are common to both children and adults. For example, any of the medical problems that would reduce the safety of diving for an adult would also do so for a child. Specific concerns about children and diving arise from the myriad of physical, physiological, pathophysiological and psychological differences between adults and children and I will review some of those that are relevant to diving below. This type of discussion is complicated by the difficulty in strictly defining a 'child'. Many of the relevant characteristics evolve with age along a gradual continuum. The adult 'form' of different characteristics may be acquired at different ages, and there may be considerable variation between individuals in this regard. Generalisations must be made with caution.

Physical differences.

Children are usually of smaller and less powerful stature than adults. Scuba gear is heavy and smaller children would find it very difficult to cope with wearing full scuba on land. Swimming with bulky scuba equipment also requires strength and stamina. Careful selection and configuration may ameliorate these problems and there is an ever-increasing range of options in sizes and styles of many items. Nevertheless, physical limitation can be an important safety issue in open water and it can be argued that children could easily find themselves in a situation where they have trouble coping. This is a critical consideration that in part predicates the requirement for certified adult supervision at Junior Open Water (JOW) level. Adults accompanying JOW divers must recognise their responsibility to avoid open water environments that may tax the less physically capable diver. Notwithstanding adult supervision, it is important that instructors teaching JOW divers carefully appraise each teenager's ability to cope with the physical demands of diving. Not all will 'make the grade' and instructors are the 'gate-keepers' in this regard. JOW diver candidates who find it physically difficult to cope must not be certified. It would be especially inappropriate at this level to simply counsel struggling students about their limitations and issue the certificate anyway.

Coordination and dexterity may be less well developed in children although by JOW diver age most children should be capable of learning diving skills to a standard comparable to that of adults. Psychological problems and limitations with mentation (see later) may be a greater barrier to the achievement of adequate skill levels than physical limitations. Nevertheless, irrespective of the reason for any difficulty in achieving adequate skill levels, the instructor once again has a crucial role in ensuring appropriate achievement prior to certification.

Another physical difference between children and adults is the higher surface area to body weight ratio seen in children. For this reason, children will drop their core temperature more rapidly when immersed or exposed to wind in a wet wetsuit. They are therefore at greater risk of becoming hypothermic. Careful attention must be given to thermal protection, especially when diving in temperate environments. This is easier said than done. Teenagers at JOW level are growing rapidly and maintaining a wetsuit that fits adequately is a difficult (and perhaps expensive) task. Nevertheless, it is most certainly not an insurmountable problem; just one that needs attention.

Almost paradoxically, these concerns are less relevant to the younger Bubblemakers because they would only ever use scuba in confined water. Equipment could be carefully tailored to the small stature of the participants in this program, and donned only when standing in the water to avoid the danger of falling while walking out of water. Achievement of excellence in skills is neither necessary nor even desirable. The aim of the program is to provide an experience, not teach how to dive. Hypothermia is unlikely to ever be a problem in a confined water situation.

Part 2

Physiological differences

One of the most obvious difference between children and adults is that children are growing. With reference to my previously specified threshold age of 15, it should be noted that growing does not stop in many teenagers until as late as 20 years. Changes in height occur mainly because of elongation of the long bones. These bones grow at their ends, in a region called the epiphysis. The epiphysis lies just behind the articular surface that helps form any joint that the bone is connected to. It functions in a manner analogous to the operation of those large roading machines that move slowly forward laying down completed road behind them. The epiphysis is a complicated 'biological machine' that moves forward leaving 'completed' bone behind. At some point in the late teenage years the epiphyses are said to 'close' and bone elongation permanently ceases.

It has been suggested that epiphyseal tissue might be vulnerable to bubble formation during decompression. The obvious concern is that any such bubbling might damage the epiphysis, cause premature closure, and therefore inhibit growth. To my knowledge however, there are no data at all from animal or human studies that support this theory. Moreover, many thousands of dives are made by divers qualified to Open Water and above who are between the ages of 15 - 20 years, and I have not yet seen any clinical reports of apparent epiphyseal damage occurring in the cases of decompression illness that have occurred in this age group. I therefore believe there is insufficient evidence supporting this theory to justify altering our recommendations about diving in teenagers. Were we truly serious about this, we would not only discourage JOW divers, but also any diver less than 20. The issue is not really relevant to Bubblemakers since the inert gas exposure in 2 metres or less would be insufficient to cause bubble formation from dissolved inert gas in any tissue on ascent. Any concerns about this risk in JOWs or Open Water Divers less than 20 year can be largely addressed by ensuring conservative diving practice in this age group.

Eustachian tube function is critical for equalising pressure in the middle ears, and is often less developed in children up to age 12-13. This is one of the reasons why young children commonly suffer protracted ear infections. By JOW diver age, there should be little difficulty in teaching candidates to valsalva effectively. However, younger 'divers' in the Bubblemaker age range may be at greater risk of aural barotrauma. Even if it is assumed that eustachian tube function is normal, it may be difficult to teach young children to reliably perform a valsalva manoeuvre. This is one of the important factors underpinning the choice of 2 meters as the absolute maximum depth for this program. Most experienced instructors teaching at Open Water level would agree that one of the problems inherent in teaching confined water sessions in 2 meters or less is that trainees often don't have to valsalva. Subsequently, problems with 'equalisation' may be unmasked in the deeper open water dives when the diver really needs to valsalva for the first time. Thus, it is likely that a descent to 2 meters would result in no aural barotrauma, even in the absence of an effective valsalva manoeuvre. Any deeper however, and the risk would increase substantially. It follows that 'Bubblemaking experiences' should never take place in water deeper than the absolute maximum of 2 meters.

Pathophysiological differences

Just as there are some diseases which are more common in adulthood, so too are there illnesses that are more common in childhood. An important category in this regard are the atopic (allergic) diseases. These include asthma, hayfever, and eczema. The argument that asthma may predispose the diver to pulmonary barotrauma and its potentially life threatening complications will be familiar to diving instructors. I would advise that children with a history of asthma are not admitted to Bubblemaker or JOW programs. At least 50% of them will grow out of their asthma at or soon after puberty and the issue of diving can then be revisited at an age where they are eligible for an Open Water course. At older ages they will be better placed to understand the issues of risk and discretionary determinations of 'fitness to dive' that are necessary when dealing with previous or very mild asthmatics. Similarly, children with active hayfever should not be admitted to these programs because hayfever may predispose to aural and sinus barotrauma. This is especially important for JOW divers who will venture into deeper water situations.

Psychological differences

In the debate over children and diving, few issues are more vexing than the differences between adults and children in psychology and mentation. Children are less able to assimilate technical information (unless it concerns computers it would seem!) and may struggle with some of the more conceptually challenging aspects of diving theory. Attention and concentration are less developed in children and they are less able to stick to a plan. They are more impetuous than adult divers and if some underwater marvel captures their attention they are more likely to swim off to explore, and less likely to worry about where their buddy is.

Once again, these considerations have implications for both instructors and adults supervising JOW divers. Instructors should not certify those candidates who struggle more than normal with basic diving knowledge, who demonstrate a tendency to panic, or who demonstrate poor levels of attention, motivation, co-operation, or teamwork. Adults supervising JOW divers should not expect vigilant monitoring of dive parameters such as air consumption, time and depth by the junior diver. Nor should they assume that the JOW diver will obediently follow them to the letter of the buddy system. The purpose of the dive for the adult should be successful supervision of the JOW diver, not, for example, filling a catch bag with crayfish.

Since the Bubblemaker will never venture outside the highly controlled confined water situation, concerns over psychology and mentation are perhaps more relevant to the JOW diver. However, it has been argued that inattention and poor appreciation of risk may increase the risk of pulmonary barotrauma (lung over-expansion) for the Bubblemaker. It is impossible to deny that divers of any age, Bubblemakers included, are at risk of pulmonary barotrauma and its life threatening complications even when diving in 2m or less. This risk can be minimised by ensuring that the 2 meter maximum depth is adhered to, and by close supervision of participating candidates by instructors.

Part 3

Is it safe for children to dive?

Commentary such as that above in which various risks are enumerated and discussed inevitably make an activity sound horrendously dangerous! What is more, no one could argue that aural barotrauma or pulmonary barotrauma is never going to occur in a Bubblemaker. No one will suggest that it would be impossible for a JOW diver to become separated from his or her supervising adult and get into serious difficulty. Eventually, all of these events will occur. But qualitative discussion of potential problems misses the point. The important questions are 'what is the incidence of these potential complications?' and 'what incidence is unacceptable?'

Many parents allow their child to ride a bike to school every day knowing that each year many will be seriously injured in accidents. Thousands of children play hard contact sports like American football or rugby despite the well-understood risk of injury. Perhaps subconsciously, parents make risk-benefit decisions about their childrens' activities every day.

Diving should be no different in this regard. However, it is difficult to assess where the various diving activities on offer to the various age groups fall with regard to relative risk. Intuitively, I think that I would be more comfortable with my 10-year-old participating in a Bubblemaker experience than riding a bicycle on a public road and there is some data to support my perception of low relative risk. First, the Confederation Mondiale des Activites Subaquatique (CMAS) has run a program similar Bubblemaker for years and now has records of close to 1,000,000 exposures without serious injury. In addition, PADI issued 122,298 JOW certifications between 1988 and 1998 and is aware of only one fatal accident involving a JOW diver. These admittedly crude data do indicate that the true risk of serious injury in these diving activities is very low. I must admit to more reservations about JOW divers than Bubblemakers, but provided both instructors and adult supervisors understand their responsibilities to the former, then these concerns are relatively minor. On the basis of my perceptions of relative risk, I believe that both the Bubblemaker and JOW diver programs will provide a rewarding and comparatively safe introduction to diving.