312 - Applied Forces during Simulated Neonatal Face-Mask Positive Pressure Ventilation

Poster Number: 312
Publication Number: 312.348

Jacqueline Hannan, University of Michigan, Ann Arbor, MI, United States; Gary M. Weiner, University of Michigan Medical School, Ann Arbor, MI, United States; Leia Stirling, University of Michigan, Ann Arbor, MI, United States

Background: Neonatal positive pressure ventilation (PPV) with a face mask requires an applied force to seal the mask against the newborn’s face. Inadequate force leads to leak and ineffective ventilation, while excess force may obstruct the airway and cause injury. The forces applied at key locations on a newborn’s face have not been described. Understanding how these forces are applied may improve training and device design.

Objective: (1) Develop a reference dataset for applied force at the mask interface and under the head, (2) Assess differences in applied forces between commonly used PPV devices and masks.

Design/Methods: Experienced neonatal healthcare providers performed simulated PPV on a high-fidelity SimNewB™ full-term manikin for two minutes in 4 separate trials. Participants used a 500-mL self-inflating bag (SIB) and NeoPuff™T-piece resuscitator with an infant anatomic inflated-rim mask (Medline) and a 60 mm round membrane-rim mask (Fisher Paykel) in a randomized 2x2 experimental design. Forces (Newtons) applied at the mentum, nasal bridge, and left and right zygomatic arch were continuously measured using ultrathin force sensors (SingleTact) applied to the manikin’s skin (Fig.1). Overall force under the manikin’s head was measured using a digital scale. Data were analyzed across each condition, and two repeated measures ANOVA were fit (mean of head and face sensor forces) to assess effects of ventilation device and mask type at each sensor, with post-hoc confidence intervals determined.

Results: 27 clinicians participated in this simulation study. There was no difference in the mean force applied under the head between the SIB and T-piece (mean difference:1.84 N, 95% CI:[-0.01, 3.69 N], p=0.052); however, participants applied less force under the head using the round compared with anatomic mask (mean difference:3.23 N, 95% CI:[1.14, 5.31 N], p=0.003) (Fig.2). No interaction between mask and PPV device was found. Differences were observed at each face sensor across all conditions with the greatest mean force applied at the left zygomatic arch (1.27 N, 95% CI:[1.07, 1.46 N]) and the least mean force applied at the mentum (0.47 N, 95% CI:[0.41, 0.52 N])  (Fig.3). No interaction effects were found between mask and PPV device at any of the face sensors.

Conclusion(s): In this study, the mean force applied to the neonatal manikin’s head during face mask PPV was decreased when using a round membrane-rim mask. Forces applied to the manikin’s face varied between locations but were not affected by device or mask type. Future analyses will correlate forces to mask leak, peak inflation pressure, and tidal volume.