Epinephrine test dose in children: is it interpretable on ECG monitor?

Background: Epidural and other regional blocks are performed in children under general anesthesia; the response to a 'test dose' may be altered during administration of general anesthetics. Limited data is available describing changes in electrocardiogram, blood pressure and heart rate (HR) following unintentional intravascular injection of a lidocaine-epinephrine-containing test dose, under sevoflurane anesthesia in children.

Methods: Sixty-eight children undergoing elective surgeries under sevoflurane anesthesia were administered 0.1 ml x kg(-1) of 1% lidocaine with epinephrine 0.5 microg x kg(-1) or normal saline intravenously, to simulate an accidental intravascular test dose. T-wave changes in lead II on the anesthesia monitor and on a printed ECG were noted over the initial 1 min as well as changes in HR and systolic blood pressure (SBP) over an initial 3 min period.

Results: Following injection of lidocaine-epinephrine, a significant increase in T-wave amplitude in lead II was noted in 91% of children on the ECG monitor and in 94% of children on the ECG printout of the same lead. In 64% of children, an increase in HR of > or =10 b x min(-1) and in 76% of children an increase in SBP of > or =15 mmHg was noted.

Conclusion: An increase in T-wave amplitude can easily be detected by carefully observing the ECG monitor or an ECG printout within a minute following the accidental i.v. administration of 0.1 ml x kg(-1) of 1% lidocaine-epinephrine (0.5 microg x kg(-1)) regional anesthetic test dose in children under sevoflurane anesthesia.