Rapid Responses to:
|
|
Rapid Responses: Rapid Responses published:
-
![[Read Rapid Response]](/icons/misc/sectionDOWN.gif)
The use of the term thromboembolism is misleading in elective orthopaedic surgery
- Almas L Khan (28 January 2006)
-
Venous thromboembolism and the Importance of Stockings
- Daniel A. Shaerf (29 January 2006)
-
Heparins are of porcine origin
- Colin White (29 January 2006)
-
potentially dangerous diagnostic pitfalls arising from diagnostic tests
- oscar,m jolobe (31 January 2006)
-
Role of venometry: An omission
- Surendra D Varman, Diraviyam Balasubramanian (3 February 2006)
|
|
|||
|
Almas L Khan, Specialist Registrar in Trauma nd Orthopaedics Freeman Hospital Newcastle NE7 7DN
Send response to journal:
|
Blan and Lip’s review of venous thromboembolism places patients undergoing elective joint replacement of the hip or knee in groups such as “strong risk factors”, or at “very high risk”. This is however highly misleading. Their statement that lower limb deep vein thrombosis has been documented in half of all major orthopaedic operations is correct, although they provide no reference for this except a link to the National Institute for Health and Clinical Excellence (NICE) and Scottish Intercollegiate Guidelines Network (SIGN) websites. These thromboses are, in the vast majority, of no clinical significance whatsoever. Unfortunately, further examination of these sites quote Warwick et al1 and Fender et al2 demonstrating the risk of symptomatic DVT at only 1.1-2.8% for hip replacements and 7-11% for knee replacements, even in patients with no thromboprophylaxis. In addition the risk of non-fatal PE is only 0.6-3%, and the risk of fatal PE is a mere 0.1-1.1%, hardly what I would call a high risk. To date not a single trial has been able to conclusively prove that any chemical thromboprophylaxis has been able to prevent a single death from PE in elective hip and knee joint replacement. According to the National Joint Registry, over 2400 joint replacements are carried out each week in the England, well above 120000 per annum, and many more in Scotland and Wales. Despite this large number, the incidence of fatal PE remains so low, that a change in its incidence due to a particular intervention remains undetectable. This is not necessarily the case in patients undergoing emergency orthopaedic surgery, however, and there is a role for thromboprophylaxis here. These views are similar to the conclusions drawn by the PEP trial3 regarding the use of aspirin in patients undergoing elective and emergency orthopaedic surgery. I would hesitate to generalise about the use of thromboprophylaxis in these groups, let alone make them into a homogenous entity. The risks of anticoagulation include persistent wound ooze and haematoma formation among others, both of which are factors in developing deep infection. As a group of patients for whom deep infection remains a problem with more serious consequences, I think it would be wise to take careful consideration before the routine use of chemical prophylaxis is applied. The BOA published its own best practice guide in 1999, in which it recommended that hip and knee replacement be regarded as moderate risk for death from pulmonary embolism. Let us not overstate its significance as an indication for the use of anticoagulant agents. Reference List (1) Warwick D, Williams MH, Bannister GC. Death and thromboembolic disease after total hip replacement. A series of 1162 cases with no routine chemical prophylaxis. J Bone Joint Surg Br 1995; 77(1):6-10. (2) Fender D, Harper WM, Thompson JR, Gregg PJ. Mortality and fatal pulmonary embolism after primary total hip replacement. Results from a regional hip register. J Bone Joint Surg Br 1997; 79(6):896-899. (3) Prevention of pulmonary embolism and deep vein thrombosis with low dose aspirin: Pulmonary Embolism Prevention (PEP) trial. Lancet 2000; 355(9212):1295-1302. Competing interests: None declared |
|||
|
|
|||
|
Daniel A. Shaerf, Preregistration House Officer, Orthopaedics and Trauma Surgery The Royal Free Hospital, Pond Street, London NW3 2QG
Send response to journal:
|
Editor: It was a delight to read in total nine pages worth of information on Venous thromboembolism (VTE) in the BMJ over the past two weeks 1,2. What did strike me amiss is that out of these nine pages only fifteen words refer to the use of compression stockings and pneumatic compression devices. I feel that these cheap and completely non-invasive means of thromboembolic deterrent should have a more marked place. The evidence behind compression stockings and pneumatic device use is well known. As long as twenty years ago there was controlled trial evidence showing the efficacy of graduated compression stockings compared to low dose heparin 3. More recently a meta-analysis showed that graduated compression stockings are a useful adjunct to Low Molecular Weight Heparins and reduce the incidence of VTE in colorectal surgery 4. Whilst I am sure everyone knows about the use of stockings in prophylaxis against VTE, I believe it important to give more space to these devices which are often used as a direct alternative to Heparins especially when the consequences of bleeding are dire. 1)Robinson GV. Pulmonary embolism in hospital practice. BMJ 2006; 332: 156-160 2)Blann AD, Lip GYH. Venous thromboembolism. BMJ 2006; 332: 215-219 3)Fasting H, Andersen K, Kraemmer Nielsen H et al. Prevention of postoperative deep venous thrombosis. Low-dose heparin versus graded pressure stockings. Acta Chir Scand. 1985; 151(3): 245-8 4)Wille-Jorgensen P, Rasmussen MS, Andersen BR et al. Heparins and mechanical methods for thromboprophylaxis in colorectal surgery. Cochrane Database Syst Rev. 2003; (4): CD001217 Competing interests: None declared |
|||
|
|
|||
|
Colin White, Consultant Physician Pontefract General Infirmary WF81PL
Send response to journal:
|
This article and last week's on pulmonary embolus made no mention of the porcine origin of heparins which is an important issue for some religions, for example, muslims. Many doctors and nurses are unaware of this and therefore cannot fully inform patients when giving advice about prophylaxis or treatment with heparin (unfractionated or low molecular weight). However, according to our trust's muslim chaplain when there is no alternative non-porcine treatment available and there is a risk to life, then it is allowable for muslims to receive a drug of porcine origin under these circumstances. Even so, some muslims may choose not to receive treatment or prophylaxis with heparin because of its porcine origin and patients do have the right to make the decision for themselves. Fondaparinux is a synthetic alternative for some of the indications for which heparins are currently used and I was interested to read that it may have advantages over low molecular weight heparin both in efficacy and cost effectiveness. Ethically, it should be available for use by muslim patients and others who object to the use of medicines of porcine origin. Competing interests: None declared |
|||
|
|
|||
|
oscar,m jolobe, retired geriatrician not appropriate(retired)
Send response to journal:
|
A shortcoming of this otherwise excellent review is that it did not draw sufficient attention to those diagnostic pitfalls which are an almost inevitable consequence of the reliance that many frontline medical staff place on diagnostic tests when differentiating between three of the most life-threatening chest pain syndromes(what I would call the three ugly sisters), namely, pulmonary embolism(PE), dissecting aortic aneurysm, and myocardial infarction. Dissecting aneutysm simulates pulmonary embolism when it presents with chest pain and/or collapse in association with an elevation in D-dimer levels of the order of > 0.5 mcg/ml(1), so much so that, according to one study "testing for d-dimer should be part of the initial assessment of patients with chest pain, especially if aortic dissection is suspected"(1). When PE presents with chest pain and an elevation in serum cardiac troponin(2) a mistaken diagnosis of myocardial infarction might lead not only to inappropriate thrombolysis, but also to a false sense of security given the likelihood that in that context, thrombolytic therapy will not be followed by a course of oral anticoagulation lasting at least three months as recommended by the authors(3). The reality is that, such is the overlap in the symptomatology of the three "ugly sisters" that, if I were to paraphrase the authors of a recent study evaluating the limitations of the chest pain history, none of the elements of the chest pain history, alone or in combination, identify a group of patients that can be safely categorised without further diagnostic testing(4). If, as in the real world, the patient with chest pain enters the diagnostic algorithm on the basis of the D-dimer test, even where PE is deemed unlikely(5), or on the basis of troponinosis, even where myocardial infarction is deemed unlikely, the consequences will be incalculable unless these diagnostic pitfalls are highlighted. OMP Jolobe References (1)Weber T., Hogler S., Auer J., et al D-dimer in Acute Aortic Dissection Chest 2003:123:1375-8 (2) Francis GS and Tang WHW Cardiac troponins in renal insufficiency and other non-ischemic cardiac conditions (3) Blann AD and Lip GYH Venous thromboembolism British Medical Journal 2006:332:215-9 (4) Swap CJ and Nagurney JT Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes Journal of the American Medical Association 2005:294:2623-9 (5) Writing Group for the Christopher Study Investigators Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-Dimer testing, and computer tomography Journal of the American Medical Association 2006:295:172-9 Competing interests: None declared |
|||
|
|
|||
|
Surendra D Varman, SpR Royal Bolton Hospital, Diraviyam Balasubramanian
Send response to journal:
|
Role of venometry: An omission Andrew D Blann et al review article on Venous thromboembolism was informative and exhaustive but not without few omissions of information regarding the diagnosis and the management of VTE. It is curious that the role of venometry (Strain gauge plethysmography ) which is well established and supported in the diagnosis of DVT was not mentioned and needless to say it is cost effective when combined with D Dimers, in evaluation of DVT in a district general hospital set up. (1) Plasma D-dimers is an end product derived from plasmin mediated degradation of cross-linked fibrin clots, and a sensitive marker for VTE but lack specificity. Therefore it cannot be used to make a positive diagnosis of VTE; however, d dimers generally have high negative predictive value and are useful as an exclusionary test, a potentially important role given that VTE is eventually ruled out in most patients investigated. (2) Flanagan et al and Robinson et al reported that computed strain gauge plethysmography can be used as a satisfactory first line investigation for the diagnosis of DVT, with a negative predictive value of 97 %.( 3, 4) As both venometry and D dimers are highly sensitive (75-95%) with a high negative predictive value ranging between 90 and 100%, they make a safer diagnostic test in ruling out a DVT with a low probability score, which obviates the need for the ultra sound, which is the current gold standard investigation. It is also known that the prevalence of DVT in patients with low clinical probability on the predictive score is around 5 %.( 5). And it had been predicted that plethysmography, together with pre- test probability scoring and a modern D-dimer test, would approach a negative predictive value of 100%, providing a cost effective strategy in the district general hospitals, where the Doppler ultrasound is still an elusive, time-consuming test and not readily available after hours. (6, 7) But the only point of contention being that Venometry though sensitive to proximal DVT, may miss out a calf DVT. A negative venometry with positive D-dimer may indicate calf DVT. Therefore these patients should undergo repeat imaging in few days time to detect extension of thrombus. (7) Treatment of DVT with LMWH in patients with renal impairment is currently not clear, though few would use a cut off of 30ml of creatinine clearance, before halving the dose.(8) The following criteria will be useful in the investigation of low probability DVT, while using the adaptation from Ho et al (8), for a high probability predictive score. .High probability of DVT:Ho et al guidelines .Low probability of DVT: Venometry & Dimer .Negative venometry& Normal D Dimer: No DVT .Negative venometry& High D Dimer: repeat venometry in 7 days and following venometry negative: No DVT venometry positive: Doppler References 1. R Sinharay, G Strang and D Bird (2002). Cost effective strategy for a safe diagnosis of deep vein thrombosis at a district general hospital. Postgraduate Medical Journal 2003; 79:363 2. Kelly J, Rudd A, Lewis RR, Hunt BJ. Plasma D-dimers in the diagnosis of venous thromboembolism. Arch Intern Med 2002 Apr 8; 162(7):747-56. 3. Flanagan DEH, Creasy T, Thomas P, et al. Computed assisted venous occlusion plethysmography in the diagnosis of acute deep vein thrombosis. Q J Med 2000; 93:277–82. 4. Robinson, Brian J., Kesteven, Patrick J. L. & Elliott, Simon T. (2002) The role of strain gauge plethysmography in the assessment of patients with suspected deep vein thrombosis. British Journal of Haematology 118 (2), 600-603. 5. Wells PS, Owen C, Doucette S, Fergusson D, and Tran H. JAMA: Does this patient have deep vein thrombosis? The Journal of the American Medical Association [NLM - MEDLINE]. Jan 11 2006.Vol.295, Iss. 2; pg. 199 6. Sinharay R. Pleuritic chest pain and hypoxia—a diagnostic dilemma. Br J Cardiol 2002; 9:589. 7. D.M. Collas, J. Brooks, P. Jacob Venometry And D-Dimer Levels In The Investigation Of Deep Venous Thrombosis - A Means Of Selecting Patients Who Do Not Require Imaging – DVT Age and Ageing, July, 2001 8. Jeff Nagge, Mark Crowther et al. Is impaired Renal function a contraindication to the Use of LMW heparin?. Arch Intern Med 2002;162:2605 -2609 9. Ho WK, Hankey GJ, Lee CH, Eikelboom JW. Venous thromboembolism: diagnosis and management of deep vein thrombosis. Med J Aust 2005;182: 476 -81.[ISI][Medline] Competing interests: None declared |
|||