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Rapid Responses: Rapid Responses published:
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echocardiography in pulmonary embolism
- dr.manan a.h. vasenwala (20 June 2003)
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Incorrect reference and link
- Michael GOODYEAR, NS CANADA B3H 2Y9 (20 June 2003)
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Guideline availability in the electronic age
- Nicholas SA Stuart (23 June 2003)
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First ever British Guideline
- Muthuramalingam Thirumaran (30 June 2003)
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Limitations of D-dimer testing
- Jonathan D Rees (2 July 2003)
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D-dimer testing should be based on a more precise estimation of the pre-test probability of PE
- Jeffrey Mann (7 July 2003)
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Diagnosis of Pulmonary Embolism in Primary Care
- Michael G Rossdale, Dr John Harvey (10 July 2003)
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dr.manan a.h. vasenwala, consultant-cardiologist (non-invasive) k.k.heart center, aligarh-202002.india
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the management of pulmonary embolism may include an echocardiogram. not only one may be fortunate in seeing a thrombus in transit in ivc, ra, rv, mpa or branches, but what effect it has on hemodynamics can be easily ascertained. also where severe hemodynamic compromise is detected, a decision to use thrombolytics can be taken on its basis.other cardiac conditions like a right myxoma, or infiltrating hypernephroma with embolism can be identified. in one case, i was fortunate to detect in a patient with suspected pe, a fibroelastoma of eustachean valve. indwelling catheters can have a thrombus attached to it.however, clinical correlation is necessary. it may not be possible to distinguish an existing right sided cardiac disease secondary to lung disease from a pulmonary embolism. Competing interests: None declared |
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Michael GOODYEAR, Assistant professor Dalhousie University, Dept Medicine, NS CANADA B3H 2Y9
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The updated guidelines (Ref 2) start on page 470, not as stated 1-14 Competing interests: None declared |
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Nicholas SA Stuart, Professor of Cancer Studies Ysbyty Gwynedd, Bangor
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Karin Janata's editorial on managing pulmonary embolism endorses the recent BTS Guidelines on Suspected Pulmonary Embolism. She also rightly expresses the hope that the guidelines will make a difference to clinical practice. It is therefore rather disappointing that the guidelines are not available freely on the web. They appear not to be available on the BTS web site and are only available on the Thorax web site to subscribers. While I understand that the publishers of Thorax will wish to protect copyright and maximise its income it would be a welcome move, in the interests of medical education and patient care, if they were generous enough to make the guidelines available to everyone. I am sure that if they did so Karin Janata's hopes would have a better chance of being realised. Competing interests: None declared |
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Muthuramalingam Thirumaran, Staff Grade Physician Dewsbury and District Hospital,Halifax road,Dewsbury,West Yorkshire WF13 4HS
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EDITOR-Karin Janata has brilliantly summarised in her editorial on the new guidelines on management of pulmonary embolism. We have to acknowledge that this is the first ever British guideline. (Italian-2001, Finnish-2000, Spanish-2001, Newzealand-1998, American-1995). Congratulations and well done to the BTS guideline development group. The group has emphasised the importance of clinical probability assessment and documentation as this can determine the results of certain imaging investigation (Ventilation perfusion scan) and also in clinical decision-making. The negative predictive value of D-Dimers cannot be underestimated. They have clearly guided us about the different assays available in the market and their sensitivities and specificities. It’s a shame still many hospitals don’t have facilities for D-Dimer assays. The guidelines group advocates Isotope scan “may” be considered as first line imaging investigation if facilities are available. The guideline group have highlighted predominantly the negative aspects of the Isotope lung scanning correctly. We all know that the Isotope lung scanning has drawbacks based on PIOPED and various other studies. I am sure everyone will agree with the author that CTPA should be the first line imaging investigation if available. The clinical implications of missing sub segmental emboli in CTPA are still debatable. The group should have highlighted the safety of Isotope Lung scan when it’s used in pregnant mothers. I will be interested to know the views of the guideline group on this issue as still some people believe that Isotope lung scan is not one hundred percent safe. Its clearly stated that there is no mortality benefit in thrombolysing non-massive PE.The group have clearly stated that there is no need to anticoagulate people for more than 4-6 weeks when the patients have a temporary risk factor. I am sure everyone will agree with me that patients are anticoagulated for longer durations than necessary. Also the importance of thrombo-prophylaxis needs to be emphasised. Hopefully this guideline will change practice. I am sure BTS will post the new guideline in their website as they normally do. Reference: 1.British Thoracic Society. Suspected acute pulmonary embolism: a practical approach. Thorax 1997; 52(suppl 4): S1-24 2.British Thoracic society guidelines for the management of suspected acute pulmonary embolism. Thorax 2003;58;470-483 3.Managing pulmonary embolism BMJ 2003; 326:1341-2 Competing interests: None declared |
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Jonathan D Rees, Specalist registrar rheumatology and general medicine Department of Rheumatology Guy's Hospital, Guy's and St Thomas' NHS Trust, St Thomas Street, LONDON
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EDITOR-The updated British Thoracic Society guidelines on the management of pulmonary embolism reviewed by Janata1 are welcomed. However the limitation of a negative D-dimer test must be emphasised. There is a misconception amongst some doctors that a negative D-dimer test excludes pulmonary embolism (PE). Indeed it has been argued in an earlier BMJ editorial that “definitive imaging might be reserved for patients with a positive [D-dimer] result.”2 Whilst this is reasonable in cases where the clinical suspicion of PE is low, this may give false reassurance where the suspicion of PE is high. As medical registrar at St Peter’s Hospital, Chertsey, I audited all patients requiring ventilation / perfusion (V/Q) scans for suspected PE over a seven month period in 2001. Sixty-seven patients with a confirmed PE had prior D-dimer testing. Of these 67 patients 7 (approximately 10%) had a negative D-dimer test. For patients where PE is strongly suspected a negative D-dimer test should therefore be interpreted with caution as it may give false reassurance. Ideally information on the sensitivity of the particular assay used should also be available. 1. Janata K. Managing pulmonary embolism. BMJ 2003;326:1341-2. (21June.) 2. Dixon AK, Coulden R, Peters AM. The non-invasive diagnosis of pulmonary embolus. BMJ 2001;323:412-3. Competing interests: None declared |
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Jeffrey Mann, Retired physician Salt Lake City, UT 84103
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I recently read the BTS's PE guidelines, and I think that it is much better (and much bolder) than most other PE guidelines. However, I think that there is one important issue that deserves greater clarification. Regarding the use of D-dimer testing, the BTS guidelines states "A negative D-dimer test reliably excludes PE in patients with low (SimpliRED, Vidas, MDA) or intermediate (Vidas, MDA) clinical probability; such patients do not require imaging for VTE." It is my belief that the above statement with respect to the Vidas D-dimer test is only correct if the patient has a pre-test clinical probability of PE < 40% and the treating clinician is willing to accept a post-test probability of PE of <5% (negative predictive value >95%) as an acceptable endpoint. Some risk-averse clinicians would only use a highly sensitive D-dimer test (eg. Vidas D-dimer test with a sensitivity of ~98%) to exclude PE if the post-test probability of PE could be reduced to <2% (negative predictive value >98%) and simple Bayesian calculations demonstrate that such a result is only possible if the pre- test clinical probability of PE is <20%. I know of no consensus threshold definitions that precisely define the threshold between low- moderate and moderate-high clinical probability of PE. I have personally used the following arbitrary definitions:- low clinical probability of PE is <20%, moderate clinical probability of PE is 21-60%, and high clinical probability of PE is >61%. If one agrees with my threshold levels, then it is theoretically not possible to reach a post-test probability of PE of <2% if the pre-test clinical probability of PE is >20% (moderate clinical probability of PE), or achieve a post- test probability of PE <5% if the pre-test clinical probability of PE is >40% (higher range of moderate probability of PE) when using the VIDAS D-dimer test in moderate probability patients. The situation is much worse with the SimpliRed D-dimer test because it has a much lower sensitivity (sensitivity ~85%), and it cannot be used to drive the post- test probability of PE to <2% (negative predictive value >98%) if the pre-test clinical probability of PE is >10% (higher range of low clinical probability of PE). See my exploratory essay [1] for further explicatory details on this important issue. I, therefore, believe that if clinicians decide to use a D-dimer test to exclude PE, then they need to make much more precise estimations of the clinical probability of PE and they also need to decide on a post-test probability of PE endpoint that they believe reliably excludes PE (eg. post-test probability of PE <2% or <5%, which translates to a negative predictive value of 98% and 95% respectively) -- prior to ordering the D- dimer test. References: 1. Mann J. A rational approach to the diagnostic workup of acute pulmonary embolism. Available at http://www.homestead.com/emguidemaps/files/PE-rationalthinking.html Competing interests: None declared |
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Michael G Rossdale, GP principal 111 Pembroke Road, Clifton Bristol BS8 3EU, Dr John Harvey
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In the past 18 months two young sportsmen in their twenties have presented to our practice with breathlessness. Both were very fit but were unable to complete the second half of their games; one played football, the other rugby. The first had some flitting chest pains, neither had any cough or haemoptysis. There was no history of recent foreign travel or immobility, no relevant family history, and they were not on medication. There were no positive findings on examination so they each had exercise pulse oximetry in the surgery. Being fit young men in their twenties they managed more than eight flights of stairs after which, their oxygen saturation was re- measured with a finger pulse oximeter. The result was a significant drop of oxygen saturation below 90% for at least one minute. They were started on low molecular weight heparin in surgery and VQ scans later confirmed the diagnosis of pulmonary embolism. This demonstrates the usefulness of exercise pulse oximetry in primary care. It is not a sensitive test but when desaturation does occur it is very likely to be due to significant lung disease or shunting. These cases also illustrate that pulmonary embolism can occur in apparently low risk individuals, and may be overlooked. Our first case had been assessed 24 hours earlier in a teaching hospital A&E Department (chest x ray and ECG only) and a previous case in a young male student was only diagnosed at post mortem. Yours faithfully Dr Michael Rossdale
Dr John E Harvey
Competing interests: None declared Editorial note
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