Keep those legs moving

first_imgKeep those legs movingOn 1 Oct 2001 in Personnel Today Related posts:No related photos. Previous Article Next Article Comments are closed. Economyclass syndrome does not discriminate – even business class travellers are atrisk. The latest research about travellers’ thrombosis is discussed.  By Hazel CullinaneTravelhealth advice for business travellers is provided by many sources includingindependent travel clinics, GP practices and occupational health departments.However, much of this advice has concentrated on travel health risks whileabroad and not on the health risks associated with the journey itself.Theissue of travellers’ thrombosis or the misleading term “economy classsyndrome” has created much media attention over the last year since thetragic death of 28-year-old Emma Christofensen of a pulmonary embolism (PE),following a flight from Australia to London. The issue of aviation health hasalso captured the attention of the House of Lords, with the Select Committee onScience and Technology producing a report on air travel and health, in November2001. This was following extensive oral and written evidence from variousparties including the airline industry, aircraft manufacturers, passengerinterest groups and medical experts. Whilethe media has raised the issue of travellers’ thrombosis it has also raisedpublic concern regarding the safety of air travel. Air travel is regarded asone of the safest forms of transport with nearly two billion passengerstravelling globally every year2. With the number of business travellersdoubling over the last 20 years occupational health practitioners are wellplaced to provide advice on travel health and related aviation health issues. Thisarticle aims to provide information and advice for occupational healthpractitioners to address the issue of travellers’ thrombosis with theirorganisation’s business travellers.Whatis travellers’ thrombosis?Ithas been known for many years that slowing of venous flow or stagnation ofblood can be a risk factor for the development of deep vein thrombosis (DVT)3.Immobility can slow circulation. This is one of the reasons why health careprofessionals encourage patients to mobilise early following surgery, and useother preventative measures including prophylactic anti-embolic stockings andanticoagulants. The calf muscles, by contracting and relaxing, exert a pumpaction on the deep veins, so sitting for prolonged periods without changingposition slows venous return, particularly in the lower legs. Circulation maybe further hindered by the compression of the popliteal vein against the edgeof the seat. Venous flow velocity has been shown to be two-thirds less sittingthan if supine4. Althoughthe term economy class syndrome was first coined by Cruickshank and colleagues4and has recently been widely used by the media, based on the theory that acramped seated position is a significant factor in the development of DVT andPE, travellers’ thrombosis can also occur in first or business class5. Equally,the risk of DVT can be associated with other forms of transport where prolongedimmobility occurs, such as during train, car and coach journeys6. The House ofLords Select Committee recommended that health care professionals and othersshould stop using the misleading term economy class syndrome but instead useflight-related DVT or travellers’ thrombosis1.Signsand symptoms Smallblood clots, which may be reabsorbed by the body, do not necessarily result inany signs or symptoms. However if the blood clot enlarges it can cause painand/or swelling of the leg, increased tenderness, redness and warmth duringtravel or even several days afterwards. DVTs are not dangerous butcomplications can arise. If part of the blood clot breaks off it can travel inthe circulatory system and block a blood vessel resulting in an embolus. Oneper cent of all people with DVT develop a PE7. While this event is rare it canbe life threatening. IncidenceAshighlighted by the House of Lords’ Select Committee report, the true incidenceof travellers’ thrombosis is unknown and further research is required1. Theincidence of deep vein thrombosis in the general population below the age of 40years is thought to be 1 per 3000 per annum8 with the incidence rate increasingwith age. Researchfindings Itis not only immobilisation that is a risk factor for deep vein thrombosis butalso a prolonged seated position. In 1940, Dr Keith Simpson, a Londonpathologist reported a six-fold increase in people dying as a result of DVTstravelling to their lungs during the blackouts of the Second World War. Theyoccurred in people who sat in crowded air raid shelters on deck-chairs, with thepopliteal vein obstructed against the wooden slat of the chair. The problem wasresolved with the introduction of sleeping bunks. Since1940 there have been several case reports of people experiencing DVT and PEfollowing long haul travel, including Homans in 1954 who identified two casesof DVT9. Since then there have been over 250 published cases of DVT thought tobe associated with travel. Unfortunatelymost of the early reports recorded single or small numbers of cases. There havebeen only a few case control studies to investigate any association betweentravel and the development of a DVT. However, the findings do not appear tocorrelate. Ferrariand colleagues’ case control study conducted in a cardiac unit in a Frenchhospital located close to an international airport found that a history ofrecent air travel occurred in 39 subjects (24.5 per cent) in the DVT group,compared to 12 cases (7.5 per cent) in the control group. Historyof travel occurred almost four times more frequently in the DVT group (oddsratio of 3.98)6, but the incidence of DVT was higher in subjects who had arecent history of car travel (28 cases) than train (2 cases) and air travel (9cases). The mean duration of travel was 5.4 hours. Kraaijenhagenand co-workers’ study  included a cohortof 1,911 patients, of which 463 (24 per cent) were diagnosed with DVT. Thirtytwo patients with DVT were compared to 104 controls where suspected DVT hadbeen ruled out. A history of prolonged travel by air, car, bus, train or boatof more than three continuous hours was investigated. Mean duration of travelwas found to be longer than seven hours. As only four of the DVT patients werefound to have a history of travel compared to 13 of the patients without DVT,no correlation was found between travel and DVT. Itcould be argued that not all confounding factors were controlled, as it ispossible that patients who had travelled had developed clots which may havespontaneously lysed and therefore they could have been assigned to the controlgroup. It could also be argued that Ferrari et al6 might have introducedreferral bias by having a prior knowledge of a history of recent long-distancetravel in the cases. Alarge retrospective study was conducted in the north of England over a 12-monthperiod in five hospitals serving a relatively fixed population of 650,000.Allpatients with DVT were asked whether they had travelled in the four weeks priorto diagnosis. It was found that only 24 cases were identified out of a total of634 cases giving an incidence of 0.4 per 10,00010. It is thought that theincidence of DVT in air travellers is small and therefore large prospectivecase control studies are required to examine symptomatic travellers for thedevelopment of travellers’ thrombosis. Riskfactors Variousrisk factors have been recognised for DVT from studies on surgical patients. Preventivemeasures Thereis little research regarding preventive measures for travellers’ thrombosis.Recently Scurr et al conducted a small randomised prospective control study tolook at the efficacy of using graduated compression stockings for airtravellers11. The study included 200 passengers over the age of 50 who wereflying long haul with a flight duration of at least eight hours. Bloodscreening, including for factor V Leiden deficiency, D-dimers and, whereappropriate, thombophilia screens and venous ultrasonography were conductedboth before and after travel. Onegroup wore below-knee graduated elastic compression stockings, the other groupdid not. Twelve passengers who did not wear the stockings developed signs ofDVT but were asymptomatic. No passengers who wore the stockings developed avenous clot. However, four of the passengers who wore  stockings developed superficial thrombophlebitis. While thefindings appear to support the case for compression stockings, not allconfounding factors were controlled, such as delays in taking D-dimersresulting in negative results but positive ultrasonography. It could also beargued that diagnosis of DVT was not confirmed by venography even thoughD-dimers were negative. The incidence of DVT was high in the study (10 percent). It could also be argued that while the study design tried to eradicatebias, the technicians carrying out ultrasonography may have been influenced bypatients discussing their experience of the flight including whether or notthey wore stockings. Subjects were also over the age of 50 and therefore theirage would put them at higher risk. Thefindings did not indicate any incidence of serious complications. BothVirgin Atlantic Airways and British Airways have special assistance departmentswho are able to advise health professionals and passengers on fitness to fly. Useof aspirinTheuse of aspirin is controversial. Aspirin has been used as a preventive measurefor heart attacks. However, further research is required to show if anybenefits can be derived for prevention of DVT. It is also important to notethat some people who take aspirin will have a gastric bleed or allergicreaction. Aswith any medication, the person should be made aware of possible side effectsand contra-indications before use. Exerciseequipment Thereare many pieces of equipment that have recently been designed to encouragepeople to exercise during a flight. The use of such equipment is up to theindividual. Gentleexercises to increase circulation can be carried out in the seat. The majorityof airlines display appropriate exercises either in in-flight magazines, inpassenger health leaflets or on in-flight entertainment systems. Post-travelItis important to inform travellers that if they do develop swollen, painful legsor breathing difficulties after a long journey they should see a local doctoras a matter of urgency. Futureresearch Ithas been recognised by the House of Lords and the World Health Organisationthat further research is required on the incidence of travellers’thrombosis,  the risk factors,preventative measures and whether there is anything intrinsic to air travelthat increases the risk of DVT.Researchersin Australia are trying to acquire funding from the Australian government toset up a multicentre case control study involving 1,600 DVT cases and 1,600matched controls, aiming at testing all modes of transport and the incidence oftravellers’ thrombosis.TheWorld Health Organisation, in collaboration with airlines through IATA, is alsoaddressing the issue of research. Study protocols are currently beingdeveloped. The UK Government, through the Department of Health, the Departmentof Transport, local government and the regions have set up an interdepartmentalAviation Health Working Group to oversee further research and to provide adviceto air travellers and the airline industry. SummaryItis important that travel health advice does not concentrate solely on thehealth risks while abroad but also includes advice on the health risksassociated with the journey. With the correct advice occupational healthpractitioners can play a significant role in advising their business travellersabout the prevention of travellers’ thrombosis. HazelCullinane, a former OH manager at Virgin Atlantic, now works with BUPAReferences1.House of Lords (1999-2000) Fifth Report, Select Committee on Science andTechnology, London: Stationary Office. 2.CAA (1999) Passengers at Gatwick, Heathrow and Manchester Airports in 1998(CAP703), CAA.3.Henriksen O (1976) Local nervous mechanism in regulation of blood flow in humansubcutaneous tissue. Acta Physiologica Scandinavica, 97:385-391.4.Cruickshank  JN, Gorlin R, Jennett R(1988) Air travel and thrombotic episodes. The economy class syndrome. Lancet ,27: 497-498.5.Ernsting J, Nicholson AN, Rainford DJ (1999) Aviation medicine, 661.Butterworth Heinemann.6.Ferrari E, Chevallier T, Chapelier A, et al (1999) Travel as a risk factor forvenous thromboembolic disease. A case study. Chest, 115: 440-444.7.Kakkar VV et al (1975) Lancet, ii: 45-51.8.Anderson F A et al (1991) Archives of .Internal Medicine, 151(5): 933-938.9.Homans J (1954) Thrombosis of the leg veins due to prolonged sitting. NewEngland Journal of Medicine, 250:148-149.10.Kesteven PLJ (2000) Travellers thrombosis. Thorax 55(Suppl 1): S32-S36.11.ScurrJH, Machin SJ, Baile-King, Mackie IJ, McDonald S & Smith PD (2001)Frequency and prevention of symptomless deep-vein thrombosis in long-haulflights: a randomised trial. Lancet, 357:9267.UsefulwebsitesHealthAdvice to Travellers:      www.doh.gov.uk/traveladvice/Departmentof Health website:  www.doh.gov.ukFCOwebsite:                           www.fco.gov.uk/travel/Knowbefore you go:                www.fco.gov.uk/knowbeforeyougoBritishAirways:                        www.britishairways.com/health/VirginAtlantic:                          www.virgin-atlantic.com/Riskfactors–People over 40 years of age–People with a history of DVT/PE or strong family history–Women who are pregnant or have had baby in the last six weeks–Previous or current history of malignant disease, heart failure or circulationproblems or who have undergone recent surgery or have injured the lower limbs–People with a current or previous history of a blood disorder that affectsblood clotting such as Factor V Leiden deficiency  –People who are dehydrated–Women taking the contraceptive pill –There is some debate as to whether obesity or current tobacco smoking aresignificant risk factors for DVT PreventivemeasuresAllpassengers should:–Avoid dehydration by limiting alcohol and caffeine-containing drinks prior toand during the flight and drink plenty of non-alcoholic drinks–Exercise calf muscles by pumping feet on the floor either standing or sittingevery 30 minutes during the journey–Take short walks around the aircraft when safe to do so, ie when seat beltsigns are off, or around the departure lounge if flight is severely delayed–Avoid sitting with legs crossed, ideally sit with feet flat on the floor orsupported by a footrest–Ideally avoid taking sleeping tablets–Breathe deeply to help improve circulationPassengerswith predisposing factors should also:–Consider wearing compression stockings, measured and fitted correctly, before theyflyIfpassengers have: –A previous or current history of clotting disorders –A family history of clotting conditions–A history of cancer –Had recent major surgery –Had a recent stroke they should consult their doctor regardingtheir fitness to fly and the possible use of a prophylactic anti-coagulant suchas low molecular heparin last_img read more

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