Abstract 1870 Poster Session I, Saturday, 5/1 (poster 42)

Development of the diaphragm in the newborn has not been extensively studied. We have previously described diaphragm ultrasonography as a noninvasive and effort independent technique to assess diaphragm thickness and performance (AJRCCM 1997:150:1570). In this study, using similar methodology, we longitudinally measured diaphragm thickness (tdi) and excursion (edi) in stable preterm infants between 26 and 37 weeks gestational age (GA). We hypothesized that in preterm infants tdi is positively related to GA, body weight (BW), body length (BL), head circumference (HC), and nutritional intake (NI). Thirty four infants (16 males and 18 females, GAs between 26-32 wks at the time of recruitment into the study) were followed longitudinally to discharge or transfer out from NICU. All infants were clinically stable and off ventilatory support at the time of inclusion into the study. Infants were studied while supine and at least one hour post prandial. We measured tdi and edi ultrasound and various anthropometric dimensions by standard techniques weekly. Daily nutritional intake was recorded. Results are shown in the table.

Table 1 No caption available
Full size table

With this study, we describe the normal tdi and edi values for stable preterm infants. Further, we found that 1) diaphragm thickness is positively correlated (p<0.01) with GA (R=0.40), BW (R=0.52), BL (R=0.53), and HC (0.49), but not with nutritional intake (R=0.09); 2) diaphragm excursion decreases with increasing gestational age. We speculate that the greater tdi with increasing GA is due to increased diaphragmatic muscle mass and greater edi at lower gestational ages reflects chest wall compliance.