Nodal Rhythm and Bradycardia During Inhalation Induction with Sevoflurane in Infants: a Comparison of Incremental and High-concentration Techniques

We studied heart rate and rhythm changes during sevoflurane inhalation induction in 60 healthy, unpremedicated infants. Patients were allocated randomly to receive an incremental (2% sevoflurane, increased every four to six breaths by 2% increments, to 8%) or high-concentration induction technique (8% sevoflurane from the outset). The ECG was recorded for 330 s (30 s pre- and 300 s postinduction) using a mini-Holter device (Recollect Dual Channel, Hertford Medical) and later analysed by an independent observer. Twelve patients developed nodal rhythm (six in each group), but no other dysrhythmias were recorded. The onset of nodal rhythm was associated with bradycardia (< 80 bpm) in seven out of 12 cases, and occurred significantly earlier in the high-concentration group (median 123 (range 99-139) s versus 164 (127-138) s). Its duration was similar in both groups (62 (2-84) s versus 90 (20-167) s). These findings highlight the importance of using continuous ECG analysis when studying volatile anaesthetic agents in young children.