Effect of intralipid on the neonatal pulmonary bed: an echographic study.

The effect of Intralipid infusion on pulmonary vascular resistance was studied prospectively by serial echocardiography on 13 occasions in six low birth weight infants. After 90 minutes of Intralipid infusion, the ratio of right ventricular preejection period to ejection time (RVPEP/ET) rose from 0.232 +/- 0.025 (mean +/- SD) to 0.285 +/- 0.035 (P = 0.0001). Of the 13 infusions studied, six (43%) resulted in RVPEP/ET values suggestive of pulmonary hypertension. Six LBW infants were observed over the same time period without Intralipid infusion, and RVPEP/ET did not change (0.209 +/- 0.035 vs 0.194 +/- 0.024). The increase in RVPEP/ET with Intralipid administration could not be explained by differences in preload or contractility, and most likely reflects an increase in pulmonary vascular tone. Caution in the use of Intralipid is recommended in infants who would be at particular risk from increased pulmonary vascular resistance.