Propofol injection pain in children: a prospective randomized double-blind trial of a new propofol formulation versus propofol with added lidocaine

The incidence of pain on injection of propofol remains unacceptably high in children, despite various strategies to reduce it. A new drug formulation of propofol has, in adult studies, been reported to cause less injection pain compared with other propofol solutions. The aim of the present prospective randomized double-blind clinical trial was to compare the incidence of pain-free injection following the use of this new formulation with that following the use of propofol with added lidocaine in children undergoing day case surgery. Eighty-three children (age range 2–18 yr) were randomized to receive 3 mg kg−1 of either Propofol-Lipuro® (propofol dissolved in a mixture of medium- and long-chain triglycerides [MCT–LCT]; group pL, n=42) or Diprivan® (propofol dissolved in long-chain triglycerides [LCT]) with added lidocaine (0.3 mg kg−1) (group pD, n=41). A specially trained nurse anaesthetist assessed the occurrence of injection pain using a four-graded pain scale. Significantly fewer patients had an entirely pain-free propofol injection in group pL (33.3%) than in group pD (61.0%) (P=0.016). A new MCT–LCT propofol formulation as a plain solution was associated with a higher incidence of injection pain than LCT propofol with added lidocaine when used for induction of anaesthesia in children.