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