Abstract 2045

Introduction:

Morphine is widely used in the NICU for analgesia and sedation. High dose opiate administration has been associated with seizures in animal models and some human studies, including our previous report in which such seizures stopped abruptly with naloxone administration.

Objective:

Our objective was to assess the frequency of occurrence of EEG abnormalities during continuous infusion of therapeutic doses of morphine (10 to 20 mcg/kg/hour) to stable infants admitted to a NICU.

Methods:

Consecutive infants admitted to the NICU who received morphine administration were the subjects for the study. They were included if gestational age at birth was >28 weeks, there were no biochemical or metabolic derangements, and there were no clinical seizures or neurological abnormalities. An EEG was performed during the infusion of morphine and was repeated >24 hours after morphine was discontinued. The clinician reading the EEGs was blinded as to whether or not the recording was done while the patient was on or off morphine. EEGs were classified as abnormal if the findings were clearly abnormal/atypical for the conceptional age.

Results:

Of 12 patients thus far studied, the mean (±SD) gestational age at birth was 33.9±3.6 weeks. The mean (±SD) birth weight was 2,112±773 g. All babies had abnormal EEGs while on morphine. In three patients (25%) the abnormal EEGs (excessive spikes) persisted while off morphine (these were premature neonates). In the other 9 infants (75%) the EEG normalized after discontinuation of morphine. The most common abnormality (11/12; 92%) was excessive interictal spiking (epileptiform activity). No seizures were recorded. Eight (67%) had discontinuous/invariant/nonreactive EEGs abnormal for conceptional age; these all reverted to normal. No baby had clinical seizures; all did well clinically and were discharged home in stable condition.

Conclusion:

Therapeutic doses of morphine can induce significant EEG changes that should be taken into consideration when interpreting EEGs on neonates. A study with longer EEG recordings, to detect nonconvulsive seizures in babies on continuous opiate infusion, appears to be justified.