DAN medics and re­searchers an­swer your ques­tions about dive medicine

Scuba Diver Australasia + Ocean Planet - - Research, Education & Medicine -

Q: I was di­ag­nosed with leukaemia and un­der­went treat­ment. I am in re­mis­sion and was re­cently cleared by my doc­tors for ex­er­cise with­out re­stric­tion. I feel well and need only sched­uled fol­lowups. I have al­ways wanted to scuba dive but am un­sure given my con­di­tion and sub­se­quent treat­ment. Can I dive, and are there any re­stric­tions or pre­cau­tions I should be aware of?

A: Symp­toms as­so­ci­ated with leukaemia in­clude dizzi­ness, fa­tigue, fever, weak­ness, weight loss, anaemia, easy bruis­ing and bleed­ing, short­ness of breath and in­fec­tions. Clearly, these all have the po­ten­tial to af­fect one’s well-be­ing while div­ing. You and your doc­tor should con­sider two im­por­tant cri­te­ria. First, div­ing should be con­sid­ered only for pa­tients

who are in re­mis­sion – as you are.

It’s im­por­tant that all divers be free from any dis­tract­ing or dis­abling symp­toms. Sec­ond, it is im­por­tant that you and your physi­cian con­firm that you are not only in good health but also have good ex­er­cise tol­er­ance. As you may know, many dive ac­ci­dents re­sult from chal­lenges posed by the div­ing en­vi­ron­ment such as cur­rents, sur­face swims, weather and sea con­di­tions. All divers must be pre­pared to face such chal­lenges be­fore re­turn­ing to the wa­ter.

[Dan Nord, EMT-P, CHT]

Q: I have no­ticed that be­gin­ning scuba divers of­ten get nose­bleeds af­ter dives. What causes them?

A: Divers, es­pe­cially new divers, some­times re­port nose­bleeds af­ter div­ing pri­mar­ily be­cause they are un­aware of the im­por­tance of equal­is­ing the si­nuses and mid­dle ears. The baro­trauma that re­sults when the si­nuses are not equalised can cause blood ves­sels in the lin­ing of the nose to burst. These ves­sels lie very close to the mu­cous mem­branes that line the nose and si­nuses, and the blood can come from ei­ther of these lin­ings. This type of baro­trauma, gen­er­ally the re­sult of air be­ing trapped within the si­nuses, is not al­ways painful, though the pres­ence of blood can be dis­con­cert­ing. With this type of in­jury, blood can also run down the back of the throat or pool in the si­nus below the eye and emerge later. It can also act as a growth medium for bac­te­ria and lead to si­nus in­fec­tions.

In­di­vid­u­als with a his­tory of si­nus trou­ble, al­ler­gies, a bro­ken nose or a de­vi­ated sep­tum as well as divers who cur­rently have a cold may find equal­i­sa­tion dif­fi­cult and may ex­pe­ri­ence prob­lems with nose­bleeds. It’s al­ways best to not dive with a cold, con­ges­tion or any other con­di­tion that might block the si­nus pas­sages.

We sug­gest a slow, gen­tle de­scent with fre­quent equal­is­ing to help de­crease the risk of si­nus baro­trauma. Divers who are un­able to equalise their si­nuses or have fre­quent nose­bleeds when scuba div­ing should see their per­sonal physi­cian or a spe­cial­ist in ear, nose and throat

(ENT) care for eval­u­a­tion.

[Dan Nord, EMT-P, CHT]

Q: Is there any rea­son cold wa­ter might in­crease the like­li­hood of lung squeeze while free­d­iv­ing? I have ex­pe­ri­enced lung squeeze a few times, but only in cold wa­ter. I was shal­lower than 30 me­tres. In warm wa­ter I can reach 50 me­tres, so I believe the squeeze is some­how re­lated to the wa­ter tem­per­a­ture.

A: You de­scribed your con­di­tion as lung squeeze, but it sounds like your ques­tion is re­ally about what might have caused you to cough up blood from your lungs (pre­sum­ably) un­der the con­di­tions you de­scribe. Given the vari­able im­pact of depth on the de­vel­op­ment of the con­di­tion, you could be ex­pe­ri­enc­ing a form of im­mer­sion pul­monary oedema (IPE).

IPE is a mul­ti­fac­to­rial con­di­tion, largely a net ef­fect of in­creased cen­tral blood vol­ume, pres­sures within the chest and, for com­pressed-gas divers, in­creased breath­ing re­sis­tance. The squeeze is a pri­mary com­po­nent, but only part of the story. Im­mer­sion pro­duces a shift in blood from the pe­riph­ery to the core, and this ef­fect can be mag­ni­fied in cold wa­ter or par­tially repli­cated by wear­ing a tight wet­suit. Ex­ces­sive fluid in­take (hy­per­hy­dra­tion) in­creases the risk.

For com­pressed-gas divers, res­pi­ra­tory load­ing (most im­por­tant, the ef­fort to in­hale) in­creases with wa­ter im­mer­sion, with breath­ing through a mouth­piece that adds re­sis­tance (par­tic­u­larly as gas den­sity in­creases) and with ex­er­tion. Us­ing com­pressed gas or free­d­iv­ing, if the net ef­fect of the var­i­ous stres­sors is a suf­fi­cient in­crease in the pul­monary artery pres­sure, cap­il­lary stress fail­ure can pro­duce a shift of blood into the lungs. Symp­toms of IPE can in­clude the per­cep­tion of strain or stiff­ness in breath­ing, cough­ing and the cough­ing up of small amounts of blood.

While I can­not con­firm that this is what you are ex­pe­ri­enc­ing, it may be that the cen­tral blood vol­ume in­crease mag­ni­fied by the cold wa­ter is the stres­sor that takes you over the edge that you skirt in warmer wa­ter ex­po­sures. IPE is most likely to ap­pear when mul­ti­ple pre­dis­pos­ing fac­tors are act­ing in con­cert. You may have found your own thresh­old.

I en­cour­age you to con­sult with your med­i­cal mon­i­tors, keeping in mind that the clas­sic squeeze is not the only risk that free­d­ivers face.

[Neal W. Pollock, PhD]

ABOVE It’s al­ways best not to dive with any con­di­tion that might block the si­nus pas­sages

BELOW Leukaemia is a type of bone mar­row can­cer of ma­lig­nant plasma cells, as­so­ci­ated with bone pain, bone frac­tures and anaemia

ABOVE Lung squeeze is the dam­age or in­jury to the lungs due t0 in­creased en­vi­ron­men­tal pres­sure on the closed gas spaces of the lungs dur­ing breath-hold div­ing

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