Table 3
Author, date and countryPatient groupStudy type (level of evidence)OutcomesKey resultsStudy weaknesses
Goldberg JS et al, 1990, UK62 men aged 18–70 years old, ASA I, II and III. Simulated difficult intubation drill, using laryngoscope to increase larynoscopy grade.Prospective observational study3 separate observers recorded time to recognition of tracheal and oesophageal intubation, by observing IR capnography, FEF end-tidal colourimeter, and auscultaion respectively.All three methods confirmed correct positioning in 100% (n=51) cases. Colourimeter and capnograph were faster than chest auscultation. All oesophageal intubations (n=11) confirmed by all 3 methods. One oesophageal intubation gave mild colour change but correctly interpreted.Study only used haemodynamically stable patients
Observers were specialist anaesthetic staff as were those intubating
Observers not blinded to other detection methods
Anton WR et al, 1991, USA60 emergency intubations, out with theatre – respiratory failure n=29, CPR n=9, self-extubation n=7, ET tube change n=6, airway protection n=3. ? other 6Prospective observational studyObservation of colour change in FEF colourimeter within 6 breaths post intubation. Observation of a positive signal from portable TRIMED IR CO2 detector within 6 breaths post intubationPositive signal of exhaled CO2 produced within 6 breaths by 59 of 60 by FEF detector, and 58 of 60 by TRIMED. Of the 9 CPR patients 5 showed a colour change that was “subtle”, into the brown range. One patient receiving CPR took 20 breaths before a positive signal was received in eitherDoctors were presumably anaesthetists
There were no oesophageal intubations
Kelly JS et al, 1992, USA20 children age 6 months to 8 years undergoing elective anaesthesiaProspective observational studyColour change in Fenem CO2 detector versus IR capnographer reading in 1.spontaneous mask ventilation 2.post tracheal intubation10 breaths during each point were monitoredOf total 400 breaths, 398 registered yellow colour in the FEF colourimeter with expiration. This correlated with capnography readings.
 2 breaths fell into brown range–both of these during mask ventilation, corrected by mask adjustmentAll patients haemodynamically stable, with optimal intubating conditions
There were no oesophageal intubations
Participants were specialist anaesthetists
Puntervoll SA et al, 2002, Norway14 female patients undergoing general anaesthesiaExperimental studyDetection of tracheal placement100% in both devicesSmall numbers
Not emergency intubation
All had both tracheal and oesophageal tubes passedDetection of oesophageal misplacementIn 5 patients with expired air placed in the oesophagus the colourimeter changed colour
CO2v capnography