Pulmonary function in infants exposed to pethidine.

OBJECTIVE: To investigate the effects of maternal pethidine administration on pulmonary function tests in newborn infants.

PATIENTS AND METHOD: The study was carried out in the Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital. The study group consisted of 20 infants exposed to pethidine within 4 hours prior to delivery. Twenty infants whose mothers received no analgesic drug or regional anesthesia were randomly selected as the controls. Narcotic related respiratory depression was determined by Apgar scores, the need for ventilatory support in the delivery room and abnormal pulmonary function measurements.

RESULTS: There was no difference in birth weight and gestational age between the two groups of infants. Pethidine was given to mothers at a dose of 72.5 +/- 7.6 mg/kg with a mean drug-delivery interval of 152 +/- 61 minutes. One infant in each group had a 1-minute Apgar score less than 7, but there was no statistical difference in the mean Apgar score between the two groups. None of the infants whose mothers received pethidine required ventilatory support, but oxygen was provided to eight infants who were apparently cyanosed at birth. Pulmonary function measurements were performed at the age of 7.4 +/- 2.3 hours in the controls and 6.0 +/- 2.5 hours in the study group. There was no significant difference in respiratory rate, tidal volume, inspiratory time, functional residual capacity, compliance and resistance between the two groups of infants.

CONCLUSION: Severe narcotic related respiratory depression was uncommon in this study. In the first 12 hours of life, there was no significant difference in pulmonary function of the infants exposed to pethidine. It is quite safe to allow the baby to room-in with the mother if respiratory depression is not presented at birth.