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Logo of bmjoInstructions for authorsCurrent ToCBMJ Open
BMJ Open. 2012; 2(5): e001785.
Published online Oct 26, 2012. doi:  10.1136/bmjopen-2012-001785
PMCID: PMC3488733
Evaluation of the self-inflating bag-valve-mask and non-rebreather mask as preoxygenation devices in volunteers
Amelia Robinson1 and Ari Ercole2
1Clinical School, University of Cambridge, Cambridge, UK
2Division of Anaesthesia, University of Cambridge, Cambridge, UK
Correspondence to Dr Ari Ercole; ae105/at/
Received July 12, 2012; Accepted September 26, 2012.
To evaluate and compare the effectiveness and tolerability of preoxygenation with the self-inflating bag-valve-mask (BVM) and non-rebreather mask (NRM) as are used before emergency anaesthesia.
Device performance evaluation.
Experimental study.
12 male and 12 female healthy volunteers (age range 24–47) with no history of clinically significant respiratory disease.
End-expiration oxygen measurements (FEO2) after 3 min of preoxygenation with BVM (without mechanical assistance) and NRM devices. Mask pressures were measured and subjective difficulty of breathing was also assessed with a visual analogue score (VAS).
Primary and secondary outcome measures
The final FEO2 achieved was 58.0% (SD 7.3%) for the NRM compared to 53.1% (SD 13.4%) for the BVM (p=0.072). Preoxygenation was associated with small increases in FECO2 that were greater for the BVM (0.50%; 95% CI 0.48 to 0.52) than the NRM (0.29%; 95% CI 0.31 to 0.28); this difference was statistically significant (p=0.028). Both devices were well tolerated on VAS assessment of difficulty of breathing although this was higher for the BVM than the NRM (median VAS 1.85/10 compared to 1.1/10; p=0.041). Inspiratory and expiratory mask pressures were higher for the BVM.
In healthy volunteers, the NRM performs comparably to the BVM in terms of the degree of denitrogenation achieved although neither performed well. Although it was well tolerated, the BVM was subjectively more difficult to breathe through and was associated with greater mask pressures and a small increase in FECO2 consistent with hypoventilation or rebreathing. Our results suggest that preoxygenation with the NRM may be a preferable approach in spontaneously breathing patients.
Keywords: Accident & Emergency Medicine
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