1. Another case of obstruction to an anaesthetic circuit
M.M. Ward, S.J. Collins 
British Journal of Anaesthesia 
Volume 90, Issue 1, Pages (January 2003)
DOI: /bja/aeg503
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
The occlusive cap fits onto the Laerdal mask and the angle piece.
British Journal of Anaesthesia  , DOI: ( /bja/aeg503)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
The normal use of a safety cap on the angle piece. The safety cap has a flange, making it impossible to connect the circuit to the Laerdal mask.
British Journal of Anaesthesia  , DOI: ( /bja/aeg503)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions