Paediatric reservoir bags: just how easily do they burst?
Jocelyn Erskine ST5Graham Bell Consultant Anaesthetist
Kevin Jerome ODPRHSC, Glasgow
Background Patients inadvertently connected to circle breathing system with APL fully closed
Risk of developing high pressure within breathing system and possibility of transmission to patient
Decision to conduct a quality control study to investigate how much pressure a reservoir bag can withstand
MethodsPre-used closed Intersurgical® reservoir bags
0.5, 1 and 2 litre sizes from cohort of batch numbers
Digital pressure monitor
Penlon Prima SP® anaesthetic machine
Outwith standard operating hours
1 pair of ear defenders!
Druck® Digital Pressure Indicator
MethodsPressure monitor connected to expiratory limb of circle via standard oxygen tubing
Patient end of the circle occluded
APL fully closed, bags inflated with an oxygen/air mix
Maximal pressure prior to each bag bursting recorded in cmH2O
iPhone App (Multi Measures, SkyPaw Co. Ltd) measured max decibels at bursting
Testing apparatus
Results91 bags: 45 x 0.5L
39 x 1L
7 x 2L
Bag size (Litres) Pburst (cmH2O) Max dB
0.5 48.3 (6.2 [31.0-60.5])
99.5 (2.3 [94-105])
1 48.7 (6.3 [35.9-61.5])
101 (1.5 [95-101])
2 32.1 (5.6 [24.5-39.5])
100 (0.7 [99-101])
Results are mean (SD[range])
Pattern of bursting
DiscussionOne of the main functions of the reservoir bag is to limit the pressure within the circuit
Law of Laplace: P= 2(tension)/R
Intersurgical® bags: made of vulcanised rubber, subjected to ISO standard quality assurance checks
No measurement of pressure required to burst bag
Bags burst at pressures <60cmH2O
Inconceivable it wouldn’t be noticed!
AcknowledgementsThanks to:
Graham Bell & Kevin Jerome
Medical Physics, RHSC
MRI Dept, RHSC
Adrian Cox at Intersurgical
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