347 - Comparison of work of breathing indices and oxygen saturation at discharge in preterm and term infants

Newborns commonly demonstrate thoracoabdominal asynchrony (TAA) secondary to highly compliant rib cage and immature respiratory muscles. Increased TAA represents increased work of breathing (WOB) indices.  Respiratory inductive plethysmography (RIP) is a noninvasive way to objectively assess TAA and  WOB indices. Normative WOB index data for full-term infants at discharge has not been established.

Objective:

To establish WOB indices (phase angle(Փ), labor breathing index (LBI), respiratory rate (RR), O₂ saturations (%) at discharge for full-term infants (born >37 weeks) and to compare these findings with those at discharge for premature infants (born 24–37-weeks' gestation) without bronchopulmonary dysplasia (BPD).

Design/Methods:

A prospective observational study was performed on infants at a single center nursery. Term infants had RIP and pulse oximetry measurements (mean ±SEM) in supine position within 48 hours of discharge. PneuRIP, a portable, bedside software, provided real time thoracoabdominal motion (Figure 1) for WOB index determinations. Term data was compared to data collected at discharge in our previous study of premature infants without BPD.  A sub-analysis of waveform data with minimal movement artifact was also performed.

Results:

Preliminary data includes 29 full- term infants. Corrected gestational age [39.20 ± 1.02 vs 31.52 ± 1.73; p< 0.01] and weight (g) at the time of study [3412 ± 426 vs 1292 ± 168; p< 0.01] differed between groups (Table 1). The WOB analysis included 79.5% of total data due to crying, apnea, & movement artifact. Phase angle was increased in term infants compared to preterm infants Փ [81^°±2 vs 67°±4; p< 0.05] & term infants had lower LBI [1.14±0.02 vs 1.38±0.04; p< 0.01], HR [126±2 vs 158±2; p < 0.01] and saturations [95%±0.5 vs 97%±0.3; p< 0.01] (Table 2). Comparison of WOB indices from a cohort of infants with minimal waveform artifact did not differ between term and preterm infants (Table 2).

Conclusion(s):

This is the first study to compare WOB indices for both term and preterm infants at discharge.  Term infants were observed to have increased movement artifact during data collection; however, trends in thoracoabdominal motion & WOB indices findings suggest that term and preterm infants have different breathing patterns. We have ongoing data collection and analysis to further delineate whether these observations represent true differences in preterm/full-term breathing patterns.