Abstract 1239 Poster Session I, Saturday, 5/1 (poster 63)

Introduction: We have previously shown that very low birth weight infants show abnormal values for compliance and resistance when studied before discharge. There is very few information if these changes correlate with lung parenchymal or airways abnormalities. Recent developments in imaging techniques, as the High Resolution CT Scan have provided a new tool to investigate the lung in a greater detail.

Objective: Study the prevalence of functional and radiological abnormalities in very low birth weight infants before discharge.

Methodology: This is a longitudinal study which includes all preterm AGA infants born with less than 1500 g and/or gestational age < 34 weeks, after january 1998. We excluded infants with congenital malformations, SGA and congenital infections. We measured air flow and esophageal pressure using a face mask, a pneumotach and a water filled catheter system. All signal were digitized in a microcomputer and stored for further analysis. Compliance (C) and Resistance (R) were calculated according to the regression analysis technique. Before discharge, infants with abnormal values for C and R (defined as C< 1.2 ml/cmH20/kg and R> 40 cmH20/ml/s)performed a High Resolution CT Scan(HRCT). The HRCT was analysed by a radiologist blind to infant condition.

Results: We admitted a total of 31 infants from January to September 98. Birth Weight was 1152+/-38 g. and Gest.Age-29.6+/-3.3 weeks (mean+/-SD). A total of 22/31 showed abnormal values for C or R according to our criteria and performed a HRCT. Mean values for all infants were: C=1.4 ml/cmH20 and R= 58 cmH20/ml/s. Out of the 22 HRCTs, 4 were classified as normal, 7 with minor changes and 11 with definite abnormalities. Most infants with low compliance had abnormal HRCTs -8/11(72%). A total of 20 infants showed normal compliance values and 11 infants in this group performed a HRCT because of R abnormalities. In this sub-group only 3/11(28%) showed definite abnormalities in the HRCT. The other infants showed minor changes or were normal, according to the Radiologist. Mean values for C in infants with abnormal HRCT were 1.17+/-0.38 vs 1.51+/-0.45 ml/cmH20/kg in infants with minor or no changes in the HRCT-p<0.05 (Fisher exact test).

Conclusions: 1) Our data show a high prevalence of lung functional and radiological abnormalities in preterm infants before discharge. 2) Abnormal values for lung compliance appear to correlate with changes in the High Resolution CT Scan.