16Alert Diver, SEAP

By DAN Medical Staff

Families should consider carefullythe decision to allow their pre-teensto dive. Do they have the physicalstamina? Do they have the copingskills in a dive emergency? Will theybe safe dive buddies?

These are just a few of theconsiderations responsible diverswant answers to before they make thedecision to let their kids learn to dive.

This statement has been developedin consultation with the DAN staffphysicians and other medicalspecialists at Duke UniversityMedical Centre.

A search of the Medline database (apart of the U.S. National Library ofMedicine that contains referencesand abstracts from 4,600 biomedicaljournals) since 1966 revealed nopapers dealing with the issue of howthe physiological differencesbetween adults and otherwisehealthy children would alter thechild's capability and risks associatedwith diving. Therefore, anyrecommendations made would bebased on theoretical considerationstaking into account what is knownabout normal growth anddevelopment, and the empiricalevidence that exists where childrenyounger than age 12 have scubadived.

In addressing the question ofchildren and diving, we haveconsidered what we feel are the mainissues that must be addressed inconsidering children and scubadiving. These are:• Since a patent foramen ovale is arisk factor in developingdecompression illness, we looked forevidence that there is an increasedincidence of patent foramen ovale(PFO) in children.• Because of differences in centralnervous system (CNS) development,is there evidence that children aremore susceptible to oxygen toxicity?• Are growing bones in pre-pubertalchildren more susceptible to injuryfrom decompression illness or silentbubbles?

• Is there any difference in the lungtissue or chest wall of childrencompared to adults, which mightmake children more susceptible topulmonary barotrauma?• Given that young children have anincreased incidence of asthmacompared to adults, is diving morelikely to trigger an asthmatic attack?• Do children have an increasedpropensity for ear barotrauma?• Are there special considerationsneeded to determine whether achild's thermal protection isadequate?• Because large amounts of venousgas emboli (VGE) are thought to beassociated with the development ofdecompression illness, is there

Young DiversDAN Offers an Assessment of Medical Issues Associated

with Children and Diving

Robert Zimmerman Photo

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evidence that children have a higherpropensity to form VGE than adults?• Are children, whose CNS is stilldeveloping, more susceptible ingeneral to decompression illnessthan adults?• If children do get decompressionillness, will an immature CNS resultin an increased severity compared toadults?• Do children have the strength andendurance to cope withemergencies?

The above are felt to be the mostimportant medical and physiologicalconsiderations in assessing the medicalissues associated with children anddiving. They do not, however, addressbehavioral or psychological issues,which may be equally, if not moreimportant than any medical andphysiological considerations and shouldbe addressed when considering theinvolvement of children in scuba diving.

Is there any evidence forincreased incidence of patentforamen ovale (PFO) in children?One paper has looked at the agedistribution of PFO.1 This paperlooked at the incidence of PFO incadavers down to age 10. They foundan increased incidence of PFO inthe 10- to 20-year-old groupcompared to other groups. They didnot specify the actual ages of thecases. However, this incidence wasbased only on six cases (three with apatent PFO) out of a total of 705,and the true binomial incidencecould be between 11 percent and 88percent. Thus, there is a suggestionof an increased incidence of PFOas age decreases below 20.

Are children more susceptible tooxygen toxicity? Clinical experiencehere at Duke University shows noparticular difference in susceptibilityof children down to age 8 to eitherpulmonary or CNS oxygen toxicity.Only a single paper was found whichattempted to address the subject.2They were only able to cite animaldata that showed that the effect ofage on susceptibility to pulmonaryoxygen toxicity was species- specific.In some instances immaturity wasprotective, in others it was not.Are growing bones moresusceptible to injury fromdecompression sickness or silentbubbles? In growing children up tothe age of 18, bones continue togrow from a region called the physis,which in log bones (arms and legs)is near each end. This area consistsof mostly cartilage and has no bloodsupply, it depends on diffusion ofsubstances to and from adjacenttissue which has a blood supply.If this area is injured, then abnormalbone growth will result, such as oneleg being longer that the other. Themain causes of injury to this regionare weight-bearing sports activitiessuch as skiing, rollerblading, iceskating, football, etc. Accidentalfractures are also common causes ofinjury to the physis.Joints are affected in musculoskeletaldecompression sickness, andosteonecrosis has been associatedwith divers who have done manynear-saturation dives, such as tunnelworkers. We do not know the exactanatomical site of joint involvement,and there is no published evidencesuggesting that the physis is moresusceptible to decompression sicknessin children compared to adults.

Children are unlikely to be exposedto the conditions most oftenassociated with osteonecrosis inadults, but sports divers dooccasionally develop osteonecrosis.Thus, we support time and depthrestrictions for children. Restrictionshave been imposed by certificationorganisations such as SSI, PADI andCMAS for children in confined andopen-water environments.

Is there any difference in the lungtissue or chest wall that mightmake children more susceptibleto pulmonary barotrauma?Up to about age 8, the pulmonaryalveoli are still multiplying,pulmonary elasticity is decreased,and chest wall compliance increased.This puts children 8 and younger ata theoretical increased risk ofpulmonary barotrauma, although wehave found nothing published in theliterature addressing this possibility.

Based on this consideration, CMAS,PADI, SDI and SSI haverecommended that children youngerthan age 8 not scuba dive, and weconcur. Given the variation in ratesof growth and maturity, it wouldeven seem prudent to raise theminimum age to closer to puberty(not less than 10 years old) to excludeany chance of children withimmature lungs from diving.Organisations including SSI, SDI andPADI have all agreed.

Are children more likely to havean asthma episode while diving?Risk factors that might provoke anasthma attack, such as cold orexercise, are present in the dryenvironment as well as underwater.However, the possibility of salt-

18Alert Diver, SEAP

water aspiration adds an additionalrisk factor. In addition, a child'sreaction to an asthma attackunderwater may involve a higherpanic component than in an adult,putting them at increased risk ofinjury. Unfortunately, there is nocontrolled study data to accept orrefute these hypotheses.

Do children have an increasedpropensity for ear barotrauma?Up to age 8, the Eustachian tube,which is responsible for equalizingthe middle ear, is more tortuous,compared to adults. This is why earinfections are more common inchildren than adults. Dr. GuyVandenhoven reported on hisexperience with 234 children, ages6-12, in a Belgian diving club from1985-1992 and found barotraumaand ear infections to be the mostcommon medical sequelae to diving.

Are there special considerationsneeded to determine whetherthermal protection is adequate?Children have a higher surface area/volume ratio and smaller bodymass, which means under similar

conditions with similar thermalprotection they will cool faster.Special attention must be paid toensure that children do not becomehypothermic during diving. Exposureprotection designed for children'ssizes is recommended wherewarranted.

Do children have a higherpropensity to form venous gasemboli (VGE) than adults? Nostudies have been done comparingpost-dive VGE incidence in childrencompared to adults.

Are children more susceptible todecompression sickness thanadults? There are no published datawhich could be used to answer thisquestion. However, organisationsincluding PADI, SSI and TDI haveall imposed depth and timerestrictions to address this.

If children do get decompressionsickness, is it likely to be ofincreased severity compared toadults? There are no published datawhich could be used to answer thisquestion.

Do children have the strengthand endurance to cope withemergencies? Children have lessstrength and endurance than adults.Whether it is sufficient to cope withemergencies, swim against currents,or board a boat under less than idealconditions is unknown, since theappropriate human factor studieshave not been carried out.

SUMMARYBased on the above considerations,the only data available that could beused to establish a minimum age fordiving are based on pulmonarydevelopment. This suggests thepossibility of and increasedsusceptibility to pulmonarybarotrauma for pre-pubertalchildren, especially those youngerthan 10 years old. There is no otherdata available that would assist inmaking this determination.

It should also be noted that theempirical data and collectiveexperience with children scubadiving seems to be based on shallow-water, protected diving. There isinsufficient information available tomake any evidence-based medicaljudgment for or against involvingchildren in scuba diving.

As more children under the age of12 dive, additional empirical datawill gradually accumulate. However,in order for this data to be useful inmaking medically based decisionsregarding children in diving, it willhave to be carefully collected, vettedand analysed.

While the above represents the fruitof DAN's best effort at looking atthe problem, we realise there may bequality data available that has notyet been published. For as wide aperspective as possible, we inviteanyone with substantive commentseither on DAN's assessment or theissues pertinent to children in divingin general to forward them the DAN.We realise that this issue willgenerate a lot of personal opinion,and while these are useful,conclusions backed up by actual dataor records are the most useful.

There is insufficient informationavailable to make any evidence-based medical judgment for oragainst involving children inscuba diving.

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