Evaluating hemodynamic and T wave criteria of simulated intravascular testdoses using bupivacaine or isoproterenol in anesthetized children

An increase in T wave amplitude greater than or equal to 25% is a reliable indicator for detecting intravascular injection of lidocaine-epinephrine te st dose in anesthetized children. We examined whether a simulated IV test d ose containing bupivacaine instead of lidocaine, and isoproterenol instead of epinephrine, produces reliable changes in heart rate (HR) and T wave mor phology. 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 pretre atment (0.01 mg/kg IV) followed by 0.25% bupivacaine containing epinephrine 0.5 mu g/kg IV, atropine followed by normal saline, atropine followed by 1 % lidocaine containing isoproterenol 0.1 mu g/kg, saline pretreatment follo wed 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 continuous ly recorded. All patients receiving the bupivacaine-epinephrine test dose a nd none receiving saline met the HR (positive if greater than or equal to 1 0 bpm increase) and T wave criteria (positive if greater than or equal to 2 5% 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.