Evaluating Hemodynamic and T Wave Criteria of Simulated Intravascular Test Doses Using Bupivacaine or Isoproterenol in Anesthetized Children

An increase in T wave amplitude > or =25% is a reliable indicator for detecting intravascular injection of lidocaine-epinephrine test dose in anesthetized children. We examined whether a simulated IV test dose containing bupivacaine instead of lidocaine, and isoproterenol instead of epinephrine, produces reliable changes in heart rate (HR) and T wave morphology. One hundred healthy infants and children (6-72 mo) were randomized to one of five groups (n = 20 each) during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen: atropine pretreatment (0.01 mg/kg IV) followed by 0.25% bupivacaine containing epinephrine 0.5 microg/kg IV, atropine followed by normal saline, atropine followed by 1% lidocaine containing isoproterenol 0.1 microg/kg, saline pretreatment followed by the lidocaine-isoproterenol test dose, and saline followed by saline. HR was recorded every 20 s and T wave amplitude of lead II was continuously recorded. All patients receiving the bupivacaine-epinephrine test dose and none receiving saline met the HR (positive if > or =10 bpm increase) and T wave criteria (positive if > or =25% increase in amplitude). The isoproterenol-containing test dose produced positive responses based only on the HR criterion with or without atropine pretreatment. Our results indicate that HR and T wave changes are useful if a bupivacaine-epinephrine test dose is used and that HR is the only useful indicator if an isoproterenol-containing test dose is used in sevoflurane-anesthetized children.