Neonatal self-inflating bags: achieving titrated oxygen delivery using low flows: an experimental study

Area of Science:

• Neonatal Resuscitation
• Respiratory Physiology
• Medical Device Engineering

Background:

• Self-inflating resuscitation bags (SIBs) are crucial for neonatal resuscitation.
• Optimizing oxygen delivery (dFiO2) from SIBs, especially at low flow rates, is essential for clinical practice.
• Understanding the impact of various parameters on dFiO2 is critical for improving patient outcomes.

Purpose of the Study:

• To determine the delivered oxygen concentration (dFiO2) during manual inflations using neonatal SIBs.
• To investigate dFiO2 at oxygen flow rates below 1 L/min.
• To assess the influence of different flow rates, peak inspiratory pressures (PIP), and inflation rates on dFiO2.

Main Methods:

• Experimental study involving 216 sets of manual inflations with two types of neonatal SIBs.
• Tested various oxygen flow rates (0.2-5.0 L/min), PIP (10-25 cmH2O), and inflation rates (30-60/min).
• Evaluated dFiO2 with and without an oxygen reservoir using a leak-proof circuit, pressure transducer, O2 analyzer, and test lung.

Main Results:

• Mean dFiO2 ranged from 75% to 93% at 5 L/min without reservoirs.
• At 1 L/min, SIBs delivered 65-85% oxygen.
• dFiO2 decreased to approximately 40% at 0.2 L/min with PIP of 20-25 cmH2O and inflations of 40-60/min.

Conclusions:

• Neonatal SIBs can achieve nearly 40% dFiO2 at clinically relevant pressures and rates using low oxygen flows.
• A graded increase in dFiO2 from 40% to 99% was observed with increasing flow rates (0.2-5 L/min) and the addition of a reservoir.
• Even at low flows, achieving dFiO2 below 40% was not possible with the tested configurations.