Optimizing oxygen delivery for neonatal resuscitation through self-inflating bags in settings without air-oxygen blenders.

Background: Resuscitation guidelines recommend fractional inspired oxygen (FiO₂) of 0.21-0.30 for infants at <35 weeks gestation. However, without an air-oxygen blender, an FiO₂ < 0.3 is difficult to achieve with a self-inflating resuscitation bag (SIRB). This study investigated the effects of adjustments to the oxygen flow rate (FR), peak inspiratory pressure (PIP), and ventilation rate (VR) on FiO₂ levels with SIRBs.

Methods: Two nondisposable SIRBs were used: a 280 mL bag (40 cm H₂O pop-off valve) and a 62 mL bag with a reservoir tube (25 and 40 cm H₂O pop-off valve). Both SIRBs were supplied with 100 % oxygen and connected to a flow meter, pressure gauge, oxygen analyzer, and test lung. FR (0.5, 1, 2, 5, or 10 L/min), PIP (20-29, 30-39, or ≥ 40 cm H₂O), and VR (40, 50, or 60/min) parameters were tested sequentially. FiO₂ was measured every 30 s for 150 s total, and each parameter combination was evaluated three times. Data were analyzed with a stepwise generalized linear model.

Results: FiO₂ levels stabilized after 60-90 s of bagging across all settings, ranging from 0.27 to 0.82 and 0.40-1.0 for the 280 and 62 mL SIRBs, respectively. A higher FR increased FiO₂ levels, whereas a higher PIP decreased FiO₂ levels. VR increases did not affect FiO₂ except at an FR ≥ 5 L/min. An FiO₂ < 0.30 was achievable only with the 280 mL SIRB at 0.5 L/min FR and PIP >40 cm H₂O. FR had the greatest effect (R² = 0.4916) on FiO₂. SIRB, PIP, VR, and bagging duration further improved the model's predictive power (R² = 0.9578).

Conclusions: A suitable SIRB, FR, PIP, and VR are crucial for FiO₂ titration in resuscitation. Further validation of these findings in clinical studies is warranted.