Phenobarbital, neonatal seizures and cerebral oxygen metabolism

Sokoloff MD, Plegue MA, Chervin RD, Barks JD, Shellhaas RA. Phenobarbital and
neonatal seizures affect cerebral oxygen metabolism: a near-infrared spectroscopy
study. Pediatr Res. 2015 Jul;78(1):91-96.

Abstract
BACKGROUND:
Near-infrared spectroscopy (NIRS) measures oxygen metabolism and is increasingly used for monitoring critically ill neonates. The implications of NIRS-recorded data in this population are poorly understood. We evaluated NIRS monitoring for neonates with seizures.
METHODS:
In neonates monitored with video-electroencephalography, NIRS-measured cerebral regional oxygen saturation (rSO₂) and systemic O₂ saturation were recorded every 5 s. Mean rSO₂ was extracted for 1-h blocks before, during, and after phenobarbital doses. For each electrographic seizure, mean rSO₂ was extracted for a period of three times the duration of the seizure before and after the ictal pattern, as well as during the seizure. Linear mixed models were developed to assess the impact of phenobarbital administration and of seizures on rSO₂ and fractional tissue oxygen extraction.
RESULTS:
For 20 neonates (estimated gestational age: 39.6 ± 1.5 wk), 61 phenobarbital doses and 40 seizures were analyzed. Cerebral rSO₂ rose (P = 0.005), and fractional tissue oxygen extraction declined (P = 0.018) with increasing phenobarbital doses. rSO₂ declined during seizures, compared with baseline and postictal phases (baseline 81.2 vs. ictal 77.7 vs. postictal 79.4; P = 0.004). Fractional tissue oxygen extraction was highest during seizures (P = 0.002).
CONCLUSIONS:
Cerebral oxygen metabolism decreases after phenobarbital administration and increases during seizures. These small, but clear, changes in cerebral oxygen metabolism merit assessment for potential clinical impact.