Best Evidence Topics

Randomised control trial

Laurent SC, de Melo AE, Alexander-Williams JM.
The use of the McCoy laryngoscope in patients with simulated cervical spine injuries.
  • Submitted by:Simon Carley - Consultant in Emergency Medicine
  • Institution:Manchester Royal Infirmary
  • Date submitted:30th November 1999
Before CA, i rated this paper: 6/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  Difficult to categorise this study.
This study used within patient controls but randomised the order in which the laryngoscopies was done.
It basically loked at the difference in laryngoscopy between a size 3 mccoy and a macintosh.
2 Design
2.1 Is the study design suitable for the objectives
2.2 Who / what was studied?
  167 elective patients. Laryngoscopy was performed with the head in the neutral position. The order (mac or mccoy) was randomised.
Assessment was made using the Cormack score.
No patients had a grade 4 view
2.3 Was this the right sample to answer the objectives?
  Not really. Emergency patients would be better, but then again, within patient controls would then be innapropriate. This design certainly informs the debate.
2.4 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  Unknown no sample size performed. Of note, there were no grade 4 views. One could argue that the clinically important difference exists when the view is poor, a study with few poor views is arguably of little relevance.
2.5 Were all subjects accounted for?
2.6 Were all appropriate outcomes considered?
  No, Laryngoscopy was the outcome whereas successful intubation is more relevant. (though the 2 are clearly closely linked)
2.7 Has ethical approval been obtained if appropriate?
2.8 Were the patients randomised between treatments?
  Yes the order of the first technique was randomised
2.9 How was randomisation carried out?
  Coin toss
2.10 Are the outcomes clinically relevant?
  Yes as laryngoscopy is important to acheive succesful intubation
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
3.2 Are the measurements valid?
  Yes Cormack score is widely used
3.3 Are the measurements reliable?
  If we believe the laryngoscopist then yes - there is the potential for observer bias here
3.4 Are the measurements reproducible?
  Should be
3.5 Were the patients and the investigators blinded?
4 Presentation of results
4.1 Are the basic data adequately described?
4.2 Were groups comparable at baseline?
  Yes as the same patient
4.3 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
4.4 Are the results internally consistent, i.e. do the numbers add up properly?
4.5 Were side effects reported?
  There were none
5 Analysis
5.1 Are the data suitable for analysis?
5.2 Are the methods appropriate to the data?
  Not sure. Mann-Whitney U used whereas Chi2 would seem more appropriate.
5.3 Are any statistics correctly performed and interpreted?
  See 5.2
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
6.2 Is the discussion biased?
7 Interpretation
7.1 Are the authors' conclusions justified by the data?
  Yes - but limited by the elective setting
7.2 What level of evidence has this paper presented? (using CEBM levels)
7.3 Does this paper help me answer my problem?
After CA, i rated this paper: 7/10
8 Implementation
8.1 Can any necessary change be implemented in practice?
  Yes - we bought a McCoy on the basis of the BET linked to this paper.
8.2 What aids to implementation exist?
8.3 What barriers to implementation exist?
  Training but to be honest this is minimal in practice.