Transcript Airtraq versus standard laryngoscopy by experienced pre

Airtraq versus standard
laryngoscopy by experienced
pre-hospital laryngoscopists in a
model of difficult intubation: a
randomised cross-over trial
M Woollard,*† D Lighton,* W Mannion,† I Johns,† P O’Meara,* C Cotton,** M
Smyth††
*School of Biomedical Sciences, Charles Sturt University, Bathurst, Australia
*†Pre-hospital, Emergency, & Cardiovascular Care Applied Research Group,
Coventry University (UK)
†ACAP New South Wales Branch
**ACAP South Australia Branch
††West Midlands Ambulance Service NHS Trust, Birmingham, UK
Conflict of interest
 The authors confirm that the manufacturers of the
Airtraq had no involvement in the
conceptualisation, design, conduct, analysis, or
write-up of this trial
 However, samples of the Airtraq were donated by
the manufacturers at no cost in support of the trial
 Funding was provided by Charles Sturt University
and the Australian College of Ambulance
Paramedics
Research question
 When used by [experienced pre-hospital
laryngoscopists managing a model of a
difficult airway] does [the Airtraq] [improve
intubation success rates] compared with
[standard laryngoscopy]?
Airtraq
Airtraq
Glottis Anatomy
Epiglottis
Vocal cords
Arytenoids
Oesophagus
Airway Classification
Cormack – Lehane Grade
Justification
 Some reports of high ETT success rates (98.4%,
n= 2,700) (Bulger et al, 2002)
 However, paramedic intubation skills are criticised
– prospective, multi-centre study reported overall ETI
success rate of 91.8% (95% CI=90.2% to 93.3%, n =
1,272)
 success rates progressed from 69.9% to 84.9% to 89.9% for the
first, second and third attempts respectively (Wang et al, 2006)
– prospective observational study (n= 208) misplaced
ETT unrecognized in 5.8% of patients (95% CI = 2.6%
to 8.9%) (Jones et al, 2004)
Justification
 Prospective in-hospital observational study n= 52
– Cumulative success rate of 71.5% after 2 attempts
– Success rate by Cormack and Lehane (1984) view




Grade I = 87.5%
Grade II = 56%
Grade III = 0%
Grade IV = 0%
– Recommended ETT should be withdrawn as a
paramedic skill (Deakin et al, 2005)
Methods
 Ethics approval from Charles Sturt
University
 Convenience sample of pre-hospital
practitioners attending the Australian
College of Ambulance Professionals
conference in Adelaide, Nov 2006
– Previously intubation trained
– Authorised to practice intubation
 Written informed consent obtained
Methods
 Study-related training
– Hand-out with text and diagrams
– Maximum of five minutes training with Airtraq
 Explanation by researcher
 Demonstration by researcher
 One practice attempt by subject
Methods
 Model of difficult intubation:
– Manikin immobilised with collar + spine
board
 Subjects not permitted to loosen / remove collar
or straps
– Tongue inflated
– Cormack & Lehane grade III (epiglottis +/arytenoids visible) or grade IV (tip of
epiglottis / no airway structures visible) view
 Depends on operator skill
Manikin model of a grade III/IV view
Methods
 Prospective randomisation of sequence in which
students attempted intubation with an 8.0mm
cuffed tube using either
– Airtraq or
– Macintosh laryngoscope with size 4 blade and
malleable stylet
 One intubation attempt undertaken with each
device
– Attempt limited to 30 seconds
– Researcher confirmed ETT placement
 ‘Difficulty of use’ scored by subjects for each
device using a 100mm visual analogue scale
Results
For Macintosh and Airtraq respectively:
– Success rates 14/56 (25%) vs. 47/56 (84%)
(59% difference, 95% CI 42 to 72%, P<0.0001);
– Oesophageal intubation rates 9/56 (16%) vs.
0/56 (0%) (-16% difference, 95% CI -9 to -28%,
P=0.0014);
– Subject-rated difficulty of use scores 86 (IQ
range 71 to 93, range 12 to 100) vs 20 (IQ
range 5 to 28, range 1 to 75), p<0.001
Other observations
 Significant dental damage inflicted during all
Macintosh intubation attempts / successes!
 Subjects always reported an excellent
(grade I) view when using the Airtraq,
regardless of whether intubation successful
Limitations
 Recruiting volunteers at a clinically-focused
conference risks reducing the generalisability of
findings (selection bias):
– Population is likely to consist of practitioners with a
greater commitment to their on-going education
– May, therefore, be more skilled in tracheal intubation
than non-attendees
 Trials involving models cannot be used as a basis
for quantitatively predicting benefit in patients
Conclusions
 In experienced pre-hospital laryngoscopists
managing a manikin model of a grade III / IV
airway view, with minimal additional training,
the Airtraq significantly:
– Increases first-time intubation success rates
– Reduces the number of oesophageal intubations
– Reduces the difficulty of intubation attempts
 It also has the potential to:
– Consistently provide grade I views
– Reduce oral / dental trauma during intubation
attempts
Contact details:
[email protected]
Prof. Malcolm Woollard, Coventry University,
Room 304 Richard Crossman Building,
Priory Street, Coventry, CV1 5FB, UK
Tel: +44 24 7679 5837
References
 Bulger EM, Copass MK, Maier RV, Larsen J, Knowles J, Jurkovich GJ.
An analysis of advanced prehospital airway management. J Emerg
Med 2002;23(2):183-9
 Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics.
Anaesthesia, 1984;39:1105-11.
 Deakin CD, Peters R, Tomlinson P, Cassidy M. Securing the
prehospital airway: a comparison of laryngeal mask insertion and
endotracheal intubation by UK paramedics. Emerg Med J
2005;22(1):64-7
 Jones JH, Murphy MP, Dickson RL, Somerville GG, Brizendine EJ.
Emergency physician-verified out-of-hospital intubation: miss rates by
paramedics. Acad Emerg Med, 2004;11(6):707-9.
 Wang HE, Yealy DM. How many attempts are required to accomplish
out-of-hospital endotracheal intubation? Acad Emerge Med,
2006;13(4):372-7.