Determination of Optimum Time for Intravenous Cannulation in Children With Dexmedetomidine Premedication

Overview

Inhalational induction with sevoflurane, nitrous oxide, and oxygen is accepted as a safe technique to avoid any movement during intravenous cannulation in children. In addition, intranasal dexmedetomidine could be used for premedication to reduce preoperative anxiety in preschool children. Early attempts to place, an intravenous line may result in movement and respiratory complications like coughing or laryngospasm. On the other hand delay in cannulation may prevent effective management of bradycardia and hypotension. There are a number of studies examining the optimum time for cannulation after sevoflurane induction. However, it is not known whether the addition of dexmedetomidine premedication affects the time for intravenous cannulation following induction with sevoflurane and nitrous oxide.

All the children will be premedicated with intranasal 2mcg/kg dexmedetomidine 40 minutes before the surgery. Ramsay sedation scale and Turkish version of modified Yale Preoperative Anxiety Scale (mYPAS) will be measured at the time of arrival in the daycare unit and during anesthesia preparation in the operating room. The same anesthesia machine will be used in all children with the same circuit volume. The circuit will be emptied and then filled with sevoflurane (8%) and nitrous-oxygen (50:50) for 30 seconds at a high fresh gas flow (6 liter/minute). The timer will be started when the face mask is placed on the child's face for inhalational induction. The exhaled gas concentrations will be measured continuously. After the loss of eyelash reflex, the fresh gas flow will be reduced to 3 liter/minute, the sevoflurane will be reduced to 5% and the timer will be restarted. Spontaneous respiration will be allowed until intravenous cannulation and ventilation will be gently assisted as required. For the first child, the gas flow settings will be maintained for 4 minutes from the loss of eyelash reflex before intravenous cannulation is attempted. All intravenous cannulation will be performed on the dorsum of the hand by an experienced anaesthesiologist, using a 24-gauge stainless steel guide cannula. At the time of intravenous cannulation attempt, an independent observer, who will be blinded about the predetermined cannulation time, will rate the movement according to a scale (0= no movement, 1= slight extremity tension, 2= extremity withdrawal, 3= generalized movement). The intravenous cannulation will be considered unsuccessful if there is any movement, cough, or laryngospasm, and the procedure will be considered successful in the absence of any reaction. The time for the subsequent patient's intravenous cannulation will be adjusted accordingly using Dixon's up-down sequential method (starting at 4 min with 15 s as the step size). The time for cannulation will be increased by 15 s if the time will be inadequate in the previous patient, and conversely, the time for cannulation will be decreased by 15 s if the time will be adequate in the previous patient. The aim of this study will be to determine the optimum time for intravenous cannulation after the induction of anesthesia with sevoflurane, oxygen, and nitrous oxide in children with intranasal dexmedetomidine premedication.