Low versus High Gas Flow Rate for Respiratory Support of Infants at Birth: A Manikin Study

Abstract

Background: Neonatal resuscitation guidelines do not specify the gas flow rate during mask ventilation. Aim: Investigating the effect of gas flow rates on pressures, volumes delivered and mask leak. Methods: Flow 5 and 10 liters/min were tested. In study part 1, pressure ranges were measured when ventilating an intubated manikin with a Neopuff®. In study part 2, pediatric staff mask-ventilated a manikin (peak inflation pressure (PIP) 30 cm H₂O, positive end expiratory pressure (PEEP) 5 cm H₂O). We measured pressures, expired tidal volume (V_Te) and mask leak. Results: Study part 1:an intubated manikin was ventilated with flow 5 versus 10 liters/min: range in PEEP was 0.4–3.6 and 2–14 cm H₂O, respectively, maximum PIP was 73 cm H₂O with both flow rates. Study part 2: when mask ventilation was given with flow 5 versus 10 liters/min: leak decreased (24% (8–85) vs. 80% (34– 94); p < 0.0001), V_Te increased (6.7 (5.1–7.8) vs. 4.7 (2.4–7.0) ml; p < 0.001), PEEP decreased (3.1 (0.8) vs. 3.7 (0.7) cm H₂O; p < 0.001), PIP was similar (28.1 (2.7) vs. 28.0 (2.3) cm H₂O; NS). Large leaks decreased V_Te and PEEP during both flow rates, PIP only with flow 5 liters/min. Conclusion: A low flow rate during neonatal mask ventilation may be a good alternative approach in reducing mask leak, provided that inflation time and flow rate warrants set pressures. Only large leaks seem to influence delivered pressures and volumes. Before resuscitation guidelines are advised, more studies on gas flow rates are needed.

Influence of the Hand Squeeze and Mask Distensibility on Tidal Volume Measurements during Neonatal Mask Ventilation

“…It was speculated that the higher pressurization, leading to larger gas distension of the mask and thus more bouncing, would explain higher incidence of leak by breaking the seal [11]. However, our current findings do not support this relationship.…”

“…Te Pas et al [11] reported that leak decreased using a lower gas flow rate (5 l/min) during PPV when compared to a higher gas flow rate (10 l/min). It was speculated that the higher pressurization, leading to larger gas distension of the mask and thus more bouncing, would explain higher incidence of leak by breaking the seal [11].…”

“…Also, although participants were told that leak was possible, less effort could have been provided to reduce mask leak given that the mask was fixated on position due to the visibility of the pressure gauge on the Neopuff. However, participants were taught that a decrease in pressure occur only when there is a large mask leak, as a recent study has shown performed in our unit [11]. …”

Changes in Positive End-Expiratory Pressure Alter the Distribution of Ventilation within the Lung Immediately after Birth in Newborn Rabbits

“…Not all positive pressure ventilation devices deliver a set PEEP reliably [31], [32] and face mask leak is common [33] and if large (>60%) substantially reduces the effective PEEP level [12]. Our results suggest that if the loss of PEEP is gradual (i.e.…”

“…However, providing consistent end-expiratory pressure support in the delivery room can be difficult and changing levels often cannot be avoided. Indeed, face mask leak is common [12], [13] and assisted ventilation is often interrupted by mask repositioning, suctioning or intubation, which can rapidly decrease lung gas volumes [14]. Little is known about how these pressure changes alter the distribution of ventilation within the immature lung.…”