129 CARDIAC OUTPUT CHANGES SECONDARY TO THEOPHYLLINE THERAPY IN PRETERM INFANTS

Article metrics

Abstract

The action of theophylline on the neonatal heart was studied in 11 clinically stable preterm infants. Mean (±SE) birth weight was 1230±390 g and the gestational age 30.7±2.8 wks. Median postnatal age was 12 days. Indications for theophylline therapy were BPD in 3, extubation in 7, and apnea in 1 neonate. Theophylline was given as IV aminophylline using a loading dose of 6.8 mg/kg and a maintenance dose of 2 mg/kg q 8 h. Cardiac output, stroke volume; and heart rate were measured using a combination of pulsed Doppler ultrasound and M-mode echocardiography before the start, on days 1, 2, 3 and 7, and after discontinuation of the drug. Arterial blood pressure was obtained by Dinamap.

An increase in cardiac output (p<0.01) was found on days 1, 2, 3, and 7. Stroke volume was significantly higher (p<0.02) on days 1, 2, 3, but comparable to pretreatment values by day 7. Heart rate was augmented significantly (p<0.01) throughout the treatment period. Mean arterial blood pressure did not change. All but one of the neonates had theophylline levels between 6 and 13 mg/1.

We conclude that during the first days of theophylline therapy both inotropic and chronotropic effects prevail. At 7 days the inotropic effect has disappeared, whereas the chronotropic effect persists. The metabolic cost of the increased cardiac output during theophylline therapy in the preterm infant deserves further attention.

Author information

Rights and permissions

Reprints and Permissions

About this article