Best Evidence Topics


Rodger MA
Diagnostic Value of Arterial Blood Gas Measurement in Suspected Pulmonary Embolism
American Journal of Respiratory and Critical Care Medicine
2000; 162: 2105-2108
  • Submitted by:Margaret Maloba - SpR
  • Institution:Manchester Royal Infirmary
  • Date submitted:28th May 2003
Before CA, i rated this paper: 7/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  very clear
2 Design
2.1 Is the study design suitable for the objectives?
  yes. To validate previously published prediction rules.
2.2 Who / what was studied?
  293 consecutive patients referred for VQ scan or pulmonary Angiography
2.3 Was a control group used if appropriate?
  not needed
2.4 Were outcomes defined at the start of the study?
2.5 Was this the right sample to answer the objectives?
2.6 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  sample size not calculated
2.7 Were all subjects accounted for?
2.8 Were all appropriate outcomes considered?
2.9 Has ethical approval been obtained if appropriate?
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
  Yes. Arterial blood gases on 155 of 212 patients. Imaging on all patients.
3.2 Was the assessment of outcomes blinded?
3.3 Was follow up sufficiently long and complete?
  Not recorded
3.4 Are the measurements valid?
3.5 Are the measurements reliable?
3.6 Are the measurements reproducible?
4 Presentation of results
4.1 Are the basic data adequately described?
4.2 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
  very clear
4.3 How large are the effects within a specified time?
4.4 Are the results internally consistent, i.e. do the numbers add up properly?
  Not quite. No blood gases on 57/212 subjects(25%)
5 Analysis
5.1 Are the data suitable for analysis?
  yes indeed
5.2 Are the methods appropriate to the data?
5.3 Are any statistics correctly performed and interpreted?
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
  yes. very much so
6.2 Is the discussion biased?
7 Interpretation
7.1 Are the author's conclusions justified by the data?
7.2 What level of evidence has this paper presented? (using CEBM levels)
  2 or 3
7.3 Does this paper help me to answer my problem?
After CA, i rated this paper: 6/10
8 Implementation
8.1 Can any necessary change be implemented in practice?
  Yes, it removes our previous reliance on blood gases in diagnosis of PE
8.2 What aids to implementation exist?
  wider availability of imaging
8.3 What barriers to implementation exist?
  difficulty with access to quick imaging
8.4 Are the study patients similar to your own?
8.5 Does the paper give any conclusions that will affect what you will offer or tell your patient?
  Yes. Negative findings in blood gases will not rule out PE