The efficacy of perfusion index as an indicator for intravascular injection of epinephrine -containing epidural test dose in ketamine-anesthetized children

Abstract

Objective Perfusion index (PI) is a noninvasive numerical value of peripheral perfusion obtained from a pulse oximeter.In this study,we evaluated the efficacy of PI for detecting intravascular injection of a simulated epidural test dose containing epinephrine in children during ketamine-based anesthesia.Methods Forty pediatric patients ASA Ⅰ,2-8 years,male,scheduled for elective surgery under ketamine basal anesthesia were randomized to receive either 0.1 ml/kg of 1％ lidocaine with epinephrine 5 mg/L or 0.1 ml/kg of saline IV (n=20 each),to simulate an accidental intravascular test dose.HR,SBP,TWA and PI were monitored for 3 min after injection.Results Injecting the test dose resulted in an average maximum PI decrease by (61.4±11.6)％ at 40 s.Moreover,maximal increases in HR(35±6) bpm,SBP[(19±10) mm Hg(1 mm Hg=0.133 kPa)] and TWA [(23.05±11.74)％]were (35±6) bpm at 20 s,60 s and 20 s after test dose injections,respectively.Using the PI criterion for intravascular injection (positive if PI decreases≥30％ from the preinjection value) the sensitivity,specificity,positive predictive,and negative predictive values were 100％.Conclusions PI is a reliable altemative to conventional hemodynamic criteria for detection of an intravaseular injection of epidural test dose in ketamine-anesthetized pediatric patients. Key words: Ketamine; Basal anesthesia; Epidural test dose; Perfusion index