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Arctic Medical Research vol. 53: Suppl. 2,pp. 320-324, 1994

Medical Care of Divers in the Antarctic

A. H. Milne and L. F. Thomson British Antaretic Survey Medical Unit, RGIT Survival Centre Ltd, Aberdeen, Scotland

Abstract: 'The provision of medical care for divers in the Antarctic presents a number of spcciil occupational health problems. For example, practices must take into account the cxlltmC nature of the environment with sea of -1.7° C and ambient temperatures .o~ -25'C with die attendant risks of . Affliction with any of the disorders associated with d1vmg. an: likely'° have serious consequences because of the remoteness of both the dive site and the base. Tius has led die British Antarctic Survey Medical Unit to focus on the specialist training of doctors and dive tezns to 1 prepare them for medical emergencies, the facility of twin lock recompression chambe~ and to ensure high level of medical fitness pre-dive. In spite of these precautions researc:~ has been earned out to:: that high standatds of safety are maintained. Previous research in Antarctlc has shown thal the core tcmperatun: was maintained during the dive a significant after drop was a~~t 40 mmutes ix: dive. These findings are now being re-examined in the light of increased diving activity throughout year and changes in protective suits.

Diving is conducted throughout the year at the Brit­ There are 2 groups of dysbari~ illn.ess, namely the ish Antarctic Survey (BAS) station on Signy (60° barotraumata and Sickness (DCSl. 43'S, 45° 36' W), one of the South Orkney group of Barottauma results from damage cOOSfllUClll islands. Signy is one of the 5 permanently manned on a change of volume of gas, aJn:adynormall~3 BAS stations, and is a centre for terrestrial, freshwa­ as gas (eg in , middle ear, smuses), as dcscett ter and marine biological research. change ofpressure. It is a phenomeno~ ofbolh aol . di . (" . 00creasmgvolume) The diving facility is important in support of the m vmg mcreasmg • . · volulllCl. research programmes. In recent years, BAS diving ascent (decreasing press.ure, mcreasmg ofBoyle's Barotramna is the pathological consequence · · activity has extended to other locations. 15 The care of divers in the remote, inaccessible and Law which states that the volume of !he ~ ; potentially hostile environment of the Ant.arctic is versely proportional to its abs?lute pressure given its absolute remams constant . IJ1IO' based on: 15 I. Safe diving practices. The most serious form of pu 3lld 2. Pre-dive and peri.odk medical examinations to nary of a.scent with its resultant Iun~ ~and establish conclusion on medical fitness or unfit­ 'b th tmP.umo-med1astm possl le pneumo orax, r·- ond'1 tionS. ast:· ness to dive. the most serious of all dive-related c . tpjnCd 3. Training in diving me.dicine for dive site doctor rial gas embolism (AGE). In AG~. gas is en the left 1 and n~-medical members of the . into the pulmonary vein, whence it tra~els. to ulafioO. 4. On-site treatment capability, in particular a side of the heart and into the systemic c~ to the recompression chamber. Usually, but not invariably, such ·~gasnav;~bolism 5. 24 hour UK-based emergency and less urgent brain, resulting in cerebral arten pidl fatal: cc;>ve~ for advice is facilitated by satellite commu­ (CAGE). Thiscondition~~st~be; uJ: mos' mcations. the most urgent treatment is mdica • ion ro. 6. Research progtamme& to iracase knowledge of important component of.. wbich is,;eco:=; of ps pocential haz.ards ancl to enable, ifindicated, addi­ following Boyle's Law, squeeze the . tional safety measures to be undertaken. into . . group; ot 1. Alertness to maintain. husband and develop the DCS, the second of the 2. dysooi:,~ solutiOD w overall and specific~ to diver care. illnesses, is caused by gas conung out ssion fOI· Each of~ above is~ furtlicr later in this form gas phase on and/or ~- dec~oading cl communication under "C - The Cate of 1he Diver." lowing, as a result of the di_ve, tne~e with }!efl­ tissues with gas in solution tn acco unt of ga.i The Diving..._ ry's Law. Henry's Law sta~ that the ~s di1t1-1l~ ~re are 3 groups of disorder which may befall the dissolved in a given ~uanttty of fl~~at gas U{ll111 diver (many refm:nces., inchKting I, 2, 3): proportional to the 0 non re511lt5 l. The dysbaric illnesses. which are those due to a the fluid. 'Ibe bubbling of gas out 0~ solu fai,.111fl· change of pressure. from tissue supersaroration ~ ......

rd WM & Thomson: Medical Care of Divers in the Antarctic 321

There are 2 inter-related events in DCS: 2. Pre-Dive and periodic medical examinations ,, The primary effects of the foreign body of the gas Robust physical and mental health is needed both for lllbble itself. If, for example, it presses on the the prolonged, isolated Antarctic tour and for diving. ;pinaJ cord, it may present as paraplegia, with The general, non-dive related, medical screening ~.urinary and bowel dysfunction. prior to departure for the South seeks to establish a b• A "secondary cascade" of effects as a result of view on medical fitness with a particular focus on: rubble/tissue interface cellular, biochemical and rheological events. (i) The health and safety of the individual and of lkpending primarily on the site of the "interro- his companions. pmg bubble", AGE and DCS may present clini­ (ii) Ability to perform the appointed tasks. (iii) The impact on individual and on operations were ~ in many ways -the "great mimicker" to borrow l!un !he description of syphilis. Features of either eg medical evacuation required for a foresee­ Mi ?" DCS include skin rash, joint pain, para­ able condition. t'lllleliae, numbness, breathlessness, unconscious­ (iv) The risk of adverse effects on the well-being and • paralysis, vestibular dysfunction, hypovola­ efficiency of the small, remote community. (v) Mininiising the difficulties for the Survey in * shock. and the more vague symptoms of fa­ llpc, gtneral malaise and change of affect. Urgent exercising its responsibility for the overall care ~ion is mandatory for AGE and DCS. of its employees. The medical examination for all scheduled Antarctic 2 ~re~ to diving, but not dysbaric per se. personnel comprises thorough: ~sbaric conditions caused by, or due to div­ (i) and past medical history, by discussion aig may be su~vided into those resulting from the with the examining doctor with reference to the P5CS that the di~er breathes (eg , , exarninee's completed questionnaire. IBlrogelJ ~is. contamination) (ii) Physical examination. ~llaneous ~up of disorders including (iii) Investigations: 3. ~ and ~e.anirnal injury. - Dipstix urinalysis. ldllll ~lated to di~g (conditions which may - Chest X-ray . . the ~ver ~non-diver alike) which require - Blood grouping (with tests for Hepatitis Band ~ pnncipally in the context of differen- C, VDRL and HIV, conducted with the exami­ ""'6'~1S from a dive-related disorder. nee' s informed consent following modified counselling. All who journey south may be re­ 1't Carter quired to either donate or receive blood). I. 54/t diving practices - Resting ECG if aged 35 or over. - Further investigations at the discretion of the ~ Divin~ ?fficer is appointed to su- 1iiists W:, stte, all d1vmg ~vi~. He plans and examining doctor. L\s ~~ to, his SCIUor colleague in The system generally permits the time and~­ Tbccqu· 10 Cambridge. tunity for clarification over any doubt regarding -.· lplllent used and procedures followed are medical fitness, eg report from family doctor, spe­ ~~an~ -:ven tried and proven. cialist referral for assessment, correction of disorder. ~of ative divmg.is undertaken, in tenns prin- The pre-tour South and annual periodic examina­ ·~~ion requirement consequent tion of the BAS diver embraces all the above plus ~the BSA~~ and time at. depth. BAS additional aspects of history, examination and inves­ ~an: J>lanned decompression table (4). tigation reflecting the UK guidelines for the statu­ ~~to be ".OOlpleted wen within the tory examination of commercial divers (6). flrao individuaJ . ts of this Table. Repetitive diving Additional investigations are ECG (routinely all ~ 1rilb any diver is. restricted to two dives in 24 ages), sub-maximal exercise test (as an indicator of frit There· ~dive being shallower than the physical fitness), full blood count, packed vol­ , IS IVOldaJJce of ultiple 'tltalled~yo- .. . . ume and sickle-cell trait, spirometr}' by vitalograph, 0 m descents/ascents Urtis~ to divmg) during any single dive (5). and audiometry. ~ llllvel to~~ diver~tcold, this ~-. the austral the dive site (by boat 3. Training in for d~v~ site doctor and non-medical members the diving team ~die sea ice du:::· ~ ski-doo and sledge of ' '"llglle, illness ~ . wmter). Doctors attend a 5 day course in Diving Medicine as Thcic is no d. ~ IDJury precludes diving. part of their pre-tour South preparation programme. -..ill'Ciiic~mg ~hen environmental condi­ The principal course objective is to ~ the ~­ lit\ ill'C lllaintained ~and treatment facili­ tor for a confident and effective role m the recogm­ ty. tion and management of the diving illnesses. Fol­ lowing review of the relevant physics and physiol-

~--~~~~~~~~~~~~~~~~~~- ···------Cin:umpolar H~olth 1993 b 322 Chapter 5: Cold: Reaction and Prottc!UJI ogy, the pathogenesis, clinical features and manage­ to prevent build-up in the chamber frfll! ment of diving illnesses are considered - with exten­ exhalation. sive reference to case history discussion. The re­ (iv) Good verbal communications between ms.t quirements of routine examination (and assessment and outside the chamber. of inter-current illness or injury) to determine medi­ (v) Adequate quantities of the minimum two gm cal are detailed. An additional day of air and l 00% oxygen. may be spent on familiarisation on operating a (vi) Medical lock. recompression chamber. (vii) Fire-fighting system. All Antarctic personnel undergo an intensive medi­ (viii)Depth capability of 50 metres of sea warct cal training course before their departure for the South. (msw)- 6 atmospheres absolute. Personal issue is made ofthe handbook to complement (ix) To cover the possible requirement for a deep this course (7). Members of the dive team attend an (eg 50 msw) and long air treatment: additional minimum of one day on diving medicine - scrubber and "diving " undertaken either before depar­ - Analysis of chamber gas, at least oxygen ml ture for the South or on Antarctic location. If the latter, carbon dioxide, by an unsophisticated systm training is given by the on site doctor. such as Draeger pump and tubes. All members of the dive team are instructed in Less acceptable alternatives to a chamber with Iii chamber operations on site by the Diving Officer. specifications listed above are: (i) A light- single-~an chamber (;g Iii 4. On Site treatment capability, in particular a "Hyperlite" - an impressive "fol.d-away reaJ. recompression chamber ily portable chamber with a maxnnum w~ Specific facility for the care ofdiving illness must be pressure of 3 ATA (20 msw) and oxygen included in the overall medical indent An on-site BIBS system). recompression chamber is mandatory. Of the diving Such a chamber would allow early ~ illnesses, AGE and DCS are the 2 outstandingly pression, and. therefore, a very good chanct predominant in requiring recOm.pression. Addition­ gaining full resolution for AGE 0~ OCS 001 ally, there would be indication for a standard dysbaric standard Jong oxygen table at m~W: fsr treatment table or hyperbaric oxygen at lesser pres­ 18 msw, the United States Navy Tab~ tude· sure for divers who have suffered eg hypoxia or The disadvantages of such a chamber JDC .:. · · t cannol ~ carbon monoxide poisonmg. As a single-man umt, ~e pa~en v~ The key to~ of AGE and OCS is recorn­ tended. This could be cruc1a1ly disad wilh pression canduc:tea as soon as possible (before the in the unconscious diver (not ~C()llllllOll bubble/s can do odJer than transient damage, and be­ CAGE) requiring care o~ the .airway. kl not ii fore the ~secoodaay cascade" develops harmfully, as - Adjunctive care, eg IV infusion, wou the latter IS not afJtcted by recompression per se - the possible. kl be m. cascade is a fluid attdirdia:t from a gaseous event, and - Clinical evaluation of progress wou will ~irucoold8aa:ewitbPascal'sPrinciple wbm complete without examination. pressurised). Olhetuwme&Jtmeasuresa impona11t­ _ Treatment depth limitations. earl tJ?S· ~ ~~the pp of oxygen, adjunct The "Hyperlite" is designed ~ an to ay ~ medicalioo IOC'Olftlet~ ere•. ment facility for transporta.tton nablittg tit The BAS R!COUlplc:ssiun chamlier has never been ''moth bamber" of dimensions e ...;..s er c . "t,andtbei-- required ~m- ·~ TWs ·tlOt.WilbstaJld the "Hypertite" to be pJaced within I ·on to c# ready availabi1i.7 Qf' a chamber is euemal. to be decanted without decoJllpresst~ It~ sugges1eda. roCOJCrcampeased air self­ of tender/s. CilcumstanCCS can:gle-Ol"1 -' ~tained ~ ~ appantl.1S (scuba) when a system combining ~~­ di~~· the.~- mew in the minimum "mother" chamber might be ilt'l'wr~ cntena for die.oa-$ito~" It is suggested that reJianee on theJ dC[toiti« (i) Twin-locl ·'!dow ~-compression/ chamber alone for the only means mere Clll It ~ompt~ of eg doctor to eg eumine care would be unwise. Howev~;.i bel1di'd1 .. diver, establish an intra-venous infusion. no doubt of the enormous poten no c~ (11) Adequate rocm in tile main chamber for com- single-man chamber rather~ usin8 31101~· fort of patient and tender. · (ii) Shallow in- recomPfeSS•?'1 ~ (iii) A minimum of2 uaits (for diver under treat­ gen breathing set has bad c_ons•~e111 •ii ment and his tender) of a built in breathing set well beyond that for which .ttte.... lllfC(ic .,. (BIBS) to enable IOOCJ, oxygen to be bftathed .. nnrnach 1n ru• racai designed (9). This '"t'Y·-~:. ·onaJ major f!omanom.....i&cemast. The BIBS is a gas line from OUbide ro jnsjdetbe.chtmber tefS: wi~ cold ':Je~g ~~~ (10) to t1teeUd agamst tts use, IS (JJSCUUlai;~ indicated· a bull pcneb-.Aaoetbouddwnpia= of concluding that it is~ Cimaipota,.~- tb1at cl Thomson: Medical Care of Divers in the Antarctic 323

The need for the facility of a recompression 5. Twenty four hour UK-based emergency and less chamber to enable with an oxygen ta­ urgent cover for advice ble is pre-eminent. Security and certainty of the UK-based BAS Medi­ The availability of other treatment measures cal Unit response to emergency are central to medi­ (before or after recompression) is important. cal care in the South. Following any necessary cardio-pulmonary re­ Satellite communications enable telex, facsimile, suscitation, the following are indicated: telephone and vax exchange of messages from and to Iii Oxygen, as close to 100% (and started as early) the stations and ships in the Antarctic. as possible, is the most important measure The most urgent matters are catered for by 24 pending recompression. Diving activity in the hour cover using one of 3 routes. The primary route Antarctic is usually located close to the cham­ entails a telephone call from the Antarctic to a dedi­ ber, but some sites are distanced from it by up cated Medical Unit number. This call leads to activa­ to 2 hours travel. tion of a (again) dedicated pager carried by a Medi­ Oxygen is carried by each dive team in the form cal Unit officer. The officer acknowledges receipt of of a Wenoll system. The Wenoll message locally, calls the Antarctic and liaises with allows administration of 100% oxygen on a BAS. (The officer carries a mobile telephone to lo~ flow rate thereby enabling a small and light cover need for response when in transit). cylmder (logistically essential) to be trans­ Two back-up or alternative communication routes ported. are available. (01 Adjunctive measures (11) should be consid­ ered. Their administration should not cause de­ 6. Research programmes lay in recompression, and they may be given in The main focus of study is on the effects of cold on the chamber at treabnent depth. The 2 most the diver. Bridgman (12) concluded that there was relevant adjuncts are: no acclimatisation to cold in Signy divers on the (a) An N infusion to correct hypovolaemia basis that there was no early onset of peripheral cold­ and ele1?Cnts of the "secondary cascade". induced vasodilatation. He demonstrated a small The regime used will be dictated by re­ drop in body core temperature which did not reach sponse. However, a useful approach is the frankly hypothermic levels (13). following in sequence: Current studies by Thomson are addressing core Colloid (BAS uses Haemaccel) 500 mis in and peripheral temperatures in divers and their sur­ 30minutes face tenders. The effects on these recordings of dive Crystalloid 500 mis over 4 hours profiles (depth and bottom~)~ activity, and ~f Colloid 500 mis over 2 hours air and sea temperatures, wmd-chill and other envi­ ronmental factors are being observed. (b) ~d. Its efficacy is controversial. Its anti- ammatory and anti-oedema properties Results are being linked to the 3 types of diving ~Y ™:Ip to restore a damaged micro­ suit used (neoprene wet suit, membrane and ~irculabon. It is held by some authorities to neoprene dry suit) to ascertain any differences in the im~ve Synaptic transmission. If used, the thermal protection they give. regune should be of high dosage for short 7. Alertness to maintain, husband and develop the duration, eg·- overall and specific approaches to diver care De~ne 12 mgs IV stat, followed All aspects of care me kept under review. ~ing 8mgs IM qid for l day and4 mgs IM qid ~ 1 knowledge and gaining of experience lead to un­ liiilAay or day· provements to safeguard the well-being of the diver. specfr:ra1 (eg care of the WlConscious) and filled . (eg b~r catheterisation - balloon Acknowledgement AgainWJth sterile saline) measures as indicated. Grateful acknowledgement is made for the contribu­ Rtom' th~se measures should not delay tion afforded by Dr W S Haston of the BAS Medical c~IOll. The ~e applies to detailed Unit and Dr MG White. the Institute Diving Officer at ~sment, which should await arrival of BAS. clinicaJ ev~de~ The onl~ pre-recompression brief)~ needed IS the (usually very References lllent to ~ of whether or not comrnit- l. Edmonds C, Lowry C, Pennefalher J. In: Diving _and pl°essure is indicated. Subacquatic Medicine, 3rd Ed. Butterworth and Heme­ ThtBAS mann, 1992. llir)' ~h to trea1!11ent of DCS and pulmo­ 2. Bennett PB, Elliott DH. In: The and Medi­ Ptndit. Of ascent IS summarised in the Ap- cine and Diving 4dl Ed. Balliere Tindall, 1993. 3. Milite AH. . In: Mills K. Morton .R. Page G. A Colour Adas of Accidents and Emergencies ------2nd Ed in Press. Wolfe ~~~~~~~~~~~~~~~~~~~ Circlllff(IOlar Health 1993 b 324 Chapter 5: Cold: ReactionandPriJftttllJI

4. RN Diving Manual (1972). HMSO London 11. Dutka AJ. 'Therapy for Dysbaric Central Ncrvru1 S"' 5. Douglas JDN, Milne AH. in tern Ishaemia. Adjuncts to Recompression. ln: 8aM Fish Fann Workers: A New Occupational . BMJ P~. Mool! R, Eds UHMS/NOAA.DAN w~(l 1991:302:1244-45 diver Accident Management. Duke Universiry, I~ 6. MA 1 ( 1987). The Medical Examination of Divers. In­ 12. Bridgeman SA. Peripheral Cold Acclimatisatioo in Alf. fonnation and Advice from the (UK) Health and Safety arctic Scuba Divers. Av, Space, Env Med I991:62:7JJ. Executive's Medical Division (Revised). 38 7. Milne AH, F.d Kutafid. British Antarctic Survey Medi­ 13. Bridgeman SA. (Cold Acclimatisation and Thenllli cal Handbook. British Antarctic Survey, 1988. Status of Antarctic Divers. (MD Thesis). Univenityd Aberdeen., Scotland, 1987. 8. US Navy Diving Manual (1979). US Govt Printing Office, Washington DC. Corresporm:t 9. Edmonds C, Lowry C, Pennefather J, In: Diving and Dr A H Milne, Senior Medical Adn111 Subacquatic Medicine 3nl Ed. 434-5, 549. Butterworth British Antarctic Survey Medical l111 and Heinemann, 1992. RGIT Survival Centrt Lal 10. Sullivan P, Vrana A. Trail of in-water Oxygen Recom­ 338 King Street, Aberdeen, AB2 381. ~ pression Therapy in Antarctica. SPUMS J 1992:22:46- 51

ApJJ1n'1ix: The BAS Approach to Treatment of DCS and Pulmonary Barotrauma ofAscent.

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Rogue Gas t.iy. {- l'lleumOthoru)} {- Mediastinal OIS} :1:_ {(-otber)} ~-r-- lf•Jlt CJR t "ted: ...... •.OllailllrlVidlila ...... ,....._ 1 Conliaue 100" mygt:ll• Surface chesl clmin (&f =~:.1.i,~> i) lb• •w18+9-u teccJWPlelllioa for JOgUe pa odicr per 1'illle {re.mber lalde:r lbm~If~· teCVi1J1RSS ia •stt:ps" IO dcplh al ...... needed respome _ S - JO - IS lllSW ii) 11-wilh axnm a> limit breadling 100• mygt:l1 by JllB,S. or ..... (nm1 ...... , ll&JFll tmleity X-rays: ...... ,.. UPl'D) - PA Clielt full - JnsPilalioll (R 'w lllndet oxygen) -EspUaDao - Lalenl (llJCICliacrin8I pa) iii)SO-. - Soft tissue toot of neck. so ..."ap·: - >...... 2 ..... so lllSW .Ollt of - ,._...._..somswP"' } ll&JFll micity ...... ,.. ll00.58. ti