Incidence of epileptiform EEG activity in children during mask induction of anaesthesia with brief administration of 8% sevoflurane

Abstract

Background: A high incidence of epileptiform activity in the electroencephalogram (EEG) was reported in children undergoing mask induction of anaesthesia with administration of high doses of sevoflurane for 5 minutes and longer. This study was performed to investigate whether reducing the time of exposure to a high inhaled sevoflurane concentration would affect the incidence of epileptiform EEG activity. It was hypothesized that no epileptiform activity would occur, when the inhaled sevoflurane concentration would be reduced from 8% to 4% immediately after the loss of consciousness.

Methodology/principal findings: 70 children (age 7-96 months, ASA I-II, premedication with midazolam) were anaesthetized with 8% sevoflurane in 100% oxygen via face mask. Immediately after loss of consciousness, the sevoflurane concentration was reduced to 4%. EEGs were recorded continuously and were later analyzed visually with regard to epileptiform EEG patterns. Sevoflurane at a concentration of 8% was given for 1.2 ± 0.4 min (mean ± SD). In 14 children (20%) epileptiform EEG patterns without motor manifestations were observed (delta with spikes (DSP), rhythmic polyspikes (PSR), epileptiform discharges (PED) in 10, 10, 4 children (14%, 14%, 6%)). 38 children (54%) had slow, rhythmic delta waves with high amplitudes (DS) appearing on average before DSP.

Conclusions/significance: The hypothesis that no epileptiform potentials would occur during induction of anaesthesia with a reduction of the inspired sevoflurane concentration from 8% to 4% directly after LOC was not proved. Even if 8% sevoflurane is administered only briefly for induction of anaesthesia, epileptiform EEG activity may be observed in children despite premedication with midazolam.

Conflict of interest statement

Competing Interests: B. Schultz and AS are members of the research group which developed the EEG classification algorithms for depth of anaesthesia that are implemented in the EEG monitor Narcotrend. In the study presented in this article the device was merely used as a means for EEG data collection. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials.

Figures

Figure 1. Delta with spikes (DSP), rhythmic polyspikes (PSR), and periodic epileptiform discharges (PED).

Typical examples are indicated by asterisks.

Figure 2. High amplitude, regular delta activity (07:53:05) and epileptiform potentials (from 07:54:24 on) during an induction of anaesthesia.

Figure 3. Spindle-shaped, regular delta activity with high amplitudes (DS) starting at 08:03:21.