Comparison of nostril sizes of newborn infants with outer diameter of endotracheal tubes.

BACKGROUND: Recommendations for endotracheal tube (ETT) size usually refer to the inner diameter (ID). Outer diameters (OD), however, vary greatly between manufacturers, which in some brands might cause difficulties in passing the ETT through the nostrils if choosing the nasal route for intubation. Even though the nostrils are dilatable by an ETT, it might be difficult to pass an ETT through the posterior naris (narrowest point of the nasal passage), if the OD is bigger than the nostrils. Therefore, nostril size may provide some guidance for the appropriate ETT size preventing unsuccessful intubation attempts. This study therefore compares nostril sizes of newborn infants with ODs of ETTs from several manufacturers. METHODS: This is a subgroup analysis of a prospective observational study, performed in a single tertiary perinatal centre in Germany. The diameter of the nostril of infants born between 34 and 41 weeks´ gestation was measured in 3D images using 3dMDvultus software and compared to the OD of ETT from five different manufacturers. RESULTS: Comparisons of nostril sizes with ODs of different ETTs were made for 99 infants with a mean (SD) birthweight of 3058g (559) [range: 1850-4100g]. Mean (SD) nostril size was 5.3mm (0.6). The OD of the 3.5mm ETT of different manufacturers ranged from 4.8-5.3mm and was thus larger than the nostril size of 20-46% of late preterm or term infants. Some OD of a 3.0mm ETT were even bigger than the OD of a 3.5mm ETT (e.g. the 3.0mm ETT from Rüsch® has an OD of 5.0mm while the 3.5mm ETT from Portex® has an OD of 4.8mm). CONCLUSIONS: Clinicians should be aware of the OD of ETTs to reduce unsuccessful intubation attempts caused by ETT sizes not fitting the nasal cavity. Generated data may help to adapt recommendations in future. TRIAL REGISTRATION: Subgroup analysis of the "Fitting of Commonly Available Face Masks for Late Preterm and Term Infants (CAFF)"-study: NCT03369028, www.ClinicalTrials.gov , December 11, 2017.

An approach to define newborns´ sniffing position using an angle based on reproducible facial landmarks.

BACKGROUND: The neutral or sniffing position is advised for mask ventilation in neonates to avoid airway obstruction. As definitions are manifold and often unspecific, we wanted to investigate the reliability and reproducibility of angle measurements based on facial landmarks that may be used in future clinical trials to determine a hypothetical head position with minimal airway obstruction during mask ventilation. METHODS: In a prospective single-center observational study, 2D sagittal photographs of 24 near-term and term infants were taken, with five raters marking facial landmarks to assess interobserver agreement of those landmarks and angle δ, defined as the angle between the line parallel to the lying surface and the line crossing Subnasale (Sn) and Porion' (P'). Angle δ was assessed in sniffing (δsniff ) and physiologic (δphys ) head position, the former based on a published, yet poorly defined head position where the tip of the nose aligns to the ceiling with the head in a supine, relaxed mid-position. RESULTS: Infants had a mean (SD) gestational age of 37.3 (2.3) weeks. Angle δ could be determined in all 48 images taken in either the sniffing or the physiological head position. Interobserver correlation coefficient was 98.6 for all measurements independent of head position. Angle δsniff was 90.5° (5.7) in the sniffing position. CONCLUSIONS: This study provides a new measuring technique using an angle that is reproducible and reliable and may be used in future studies to correlate head position with airway obstruction.

Do commonly available round facemasks fit near-term and term infants?

OBJECTIVE: With inappropriately large facemasks, it is more difficult to create a seal on the face, potentially leading to ineffective ventilation during neonatal stabilisation. We investigated whether commonly available round facemasks are of appropriate size by measuring facial dimensions in near-term and term infants using two-dimensional (2D) and three-dimensional (3D) images. DESIGN: Prospective single-centre observational study. SETTING: Infants born in our centre at 34-41 weeks' gestation were eligible. INTERVENTION: Patients were photographed with 2D and 3D technique. MAIN OUTCOME MEASURES: Distances between nasion and gnathion were measured and compared with the outer diameter of various round facemasks. METHODS: 2D and 3D images were performed using standard equipment. Correlations between gestational age and the above-mentioned distances were assessed using Pearson's r. RESULTS: Images were taken from 102 infants with a mean (SD) gestational age of 37.9 (2.3) weeks. Mean distance between nasion and gnathion was 46.9 mm (5.1) in 2D and 49.9 mm (4.1) in 3D images, that is, on average 3 mm smaller in 2D than with 3D (p<0.01). Based on these measurements, round facemasks with an external diameter of 50 mm seemed fitting for most (61%) term infants and 42 mm masks for most (72%) near-term infants (GA 34-36 weeks). CONCLUSIONS: Round facemasks with an external diameter of 60 mm are too large for almost all newborn infants, while 42/50 mm round facemasks are well fitting. Important anatomical structures were only visible using 3D images. CLINICAL TRIAL REGISTRATION NUMBER: NCT03369028.