Comparison of Perfusion Index, T Wave Amplitude, Systolic Blood Pressure and Heart Rate

• change of perfusion index from baseline [ Time Frame: during 5 min after injection of epinephrine containing test dose or saline ] [ Designated as safety issue: Yes ]
  we will observe the change of perfusion index from baseline during 5 min after injection of epinephrine containing test dose or saline. Patients whose perfusion index decrease more than 25% are defined as positive response.we will obtain the sensitivity, specificity, positive predictive value, negative predictive value using perfusion index criteria to determine the reliability of perfusion index criteria.
  
  

• change of systolic blood pressure, heart rate, T-wave amplitude from baseline [ Time Frame: during 5 min after injection of epinephrine containing test dose or saline ] [ Designated as safety issue: Yes ]
  

Intravenous injection of local anesthetics could result in life-threatening complications during general anesthesia. Physicians usually use local anesthetics containing epinephrine to detect intravascular injection. Existing methods including heart rate, systolic blood pressure and T-wave amplitude are unreliable to detect intravascular injection during anesthesia and a method using changes in perfusion index was recently suggested. This study was designed to determine whether perfusion index is a reliable method to detect intravascular injection of epinephrine containing local anesthetics and to compare its reliability with conventional criteria in sevoflurane anesthetized adults.

We will randomize patients to 2 groups: a saline group and an epinephrine group. Changes in perfusion index, systolic blood pressure, heart rate and T-wave amplitude will be measured during 5 minutes after injection of 3 mL of saline or 1% lidocaine containing epinephrine. we will determine sensitivity, specificity, positive predictive value and negative predictive value.