Effect of Different Low Flow Rates on Gas Exchange in Anesthetized Children During Apnea A Single Blinded Randomized Study

Introduction: During induction of general anesthesia using muscle relaxant, all patients experience a period of apnea which begins when mask ventilation is stopped prior to laryngoscopy and tracheal intubation and ends when ventilation is resumed. This period is a critical time as pediatrics especially infants and younger children are more liable for hypoxia than older children and adolescents. Hypoxia during this period of time in turn, had been proved to increase morbidity and mortality. Apneic oxygenation means uptake of oxygen by the blood from the lungs in the absence of spontaneous respiration or positive pressure ventilation, and its effectiveness in reducing the risk of hypoxemia during intubation in children had been proved. Many variables and outcomes had been studied during low flow apneic oxygenation in pediatrics and it was found that, it doesn't not only reduce the risk of hypoxemia but also prolongs of the safe apnea time up to 6 mins even when compared with high flow apneic oxygenation.

Anesthetic technique:

All children will undergo routine preoperative investigations: Complete blood count and coagulation profile. First, they will be examined as regards the fulfillment of inclusion criteria to be in the study or to be excluded from the study. Then, All children will receive premedication using midazolam 0.5 mg/kg intramuscular and intramuscular atropine 0.02 mg /kg.

Before induction of anaesthesia, patient characteristics and vital signs will be recorded {pulse oximetry, ECG, non-invasive blood pressure, end-tidal carbon dioxide}and will be applied all over the operation.

While establishing of IV access, all children will be preoxygenated using 6 liter/min of 100% O2 for 3 mins and if there will be a difficulty in obtaining an IV access, patients will be induced with inhaled sevoflurane followed by the placement of an IV cannula. Then, 2-3mg/Kg of Propofol, 1mcg/Kg of Fentanyl, and 0.3-0.5 mg/kg of Atracurium will be given. During induction of anesthesia an expert pediatric anesthesiologist will introduce an arterial radial cannula.