2020A12 Using a labelled diagram, describe how a self-inflating bag-valve-mask resuscitation device works.

Use

· Spontaneous ventilation

· Mechanical ventilation

Pros

Logistics:

· Simple

· Cheap

· Portable

· No power required (hand-compressible, self-expanding bag

· No O₂ supply required (air inlet valve opens if subatmospheric)

Function:

· Compatible with face mask, LMA, ETT (15mm adaptor)

· Can deliver 100% O₂ (2L bag + large reservoir)

· Protection against barotrauma (high pressure relief valve ~30cmH₂O)

· Minimal dead space (non-rebreather valve close to patient)

· Relatively low resistance to flow in inspiration

· Minimal waste of fresh gas (one-way refill valve)

Cons

Logistics:

· Bulky near patient’s head

· No measurements (pressure, flow, CO₂)

Function:

· Easy to overventilate + insufflate the stomach (rapidly re-inflating bag)

· Spont vent inspiratory pressure drop of 2cmH₂O exceeds recommendation

· Valve malfunction or misassembly can cause barotrauma, failure of oxygenation and ventilation

Fun fact: AMBU = artificial manual breathing unit