Neonatal self‐inflating bags: Achieving titrated oxygen delivery using low flows: An experimental study

Aim To determine delivered O 2 concentration ( d FiO 2 ) during manual inflations using neonatal self‐inflating resuscitation bags ( SIBs ) at oxygen ( O 2 ) flow rates <1  L /min. Methods This experimental study, determined d FiO 2 during 216 sets of manual inflations at different O 2 flow rate ( L /min; 0.2, 0.4, 0.6, 0.8, 1.0 and 5.0), controlling peak inspiratory pressures ( PIP ; cm of H 2 O ; 10–15, 15–20 and 20–25), inflation rates (per min; 30, 40 and 60), with and without O 2 reservoir using two SIBs – the Laerdal infant resuscitator (240  mL ) and A mbu M ark IV resuscitator (300  mL ). A leak proof circuit connecting the SIB in series with pressure transducer, O 2 analyzer and test lung was used. All possible combinations were tested four times each. The d FiO 2 with each possible combination was compared using generalised estimating equation. Results The mean d FiO 2 with SIB even without reservoirs varied with rates and PIP from 75 to 93% at O 2 flow rate of 5  L /min. At 1  L /min flow itself, 65–85% O 2 is delivered. The d FiO 2 was reduced to approximately 40% with flow of 0.2  L /min, PIP 20–25 cmH 2 O and inflations 40–60 per min. Conclusion During manual breaths using neonatal SIBs , the delivered O 2 concentration of nearly 40% is attained at clinically used inflation pressures and rates by using lower flows. A graded increase in O 2 delivery from 40 to 99% was obtained with flow varying from 0.2 to 5  L /min and addition of reservoir. However, even at such low flows, reduction in O 2 concentration below 40% was unattained.