Verification of Appropriate Insertion Depth of Endotracheal Tube Placement in Infants and Young Children by Ultrasonography

• time to verification of appropriate insertion depth of endotracheal tube placement [ Time Frame: 10 min after anesthetic induction ] [ Designated as safety issue: Yes ]
  time to verification of appropriate insertion depth of endotracheal tube placement by a independent observer
  
  

• incidence of repositioning of endotracheal tube placement [ Time Frame: 20 min after anesthetic induction ] [ Designated as safety issue: Yes ]
  incidence of repositioning of endotracheal tube placement (when it is found that the depth of endotracheal tube placement was inadequate by pulse oximetry or airway pressure monitoring)
  
  
• the incidence of inadequate depth of endotracheal tube placement by chest X-ray after surgery [ Time Frame: 30 minutes after the end of surgery ] [ Designated as safety issue: Yes ]
  the incidence of inadequate depth of endotracheal tube placement by chest X-ray after surgery assessed by the radiologist
  
  
• blood pressure [ Time Frame: 5, 10, 20 min after anesthetic induction ] [ Designated as safety issue: Yes ]
  systolic, diastolic, mean blood pressure before attempt of endotracheal intubation (5 min), during determining the depth of endotracheal tube placement (10 min), after determining the depth of endotracheal tube placement (20 min)
  
  
• heart rate [ Time Frame: 5, 10, 20 min after anesthetic induction ] [ Designated as safety issue: Yes ]
  heart rate before attempt of endotracheal intubation (5 min), during determining the depth of endotracheal tube placement (10 min), after determining the depth of endotracheal tube placement (20 min)
  
  
• pulse oximetry [ Time Frame: 5, 10, 20 min after anesthetic induction ] [ Designated as safety issue: Yes ]
  pulse oximetry before attempt of endotracheal intubation (5 min), during determining the depth of endotracheal tube placement (10 min), after determining the depth of endotracheal tube placement (20 min)
  
  

It is difficult to determine the adequate depth of endotracheal tube placement in infants and young children. It is usually determined by an equation according to the patient's age (12 + age/2, cm) or auscultation method. The auscultation method is to intentionally place the tip of the endotracheal tube into the right main stem bronchus and then withdraw it until breath sounds are equal. The tube is fixed 1 or 2 cm proximal to the point where breath sounds become equal. However, in small children or infant, as the breadth sound in unilateral lung transmits the contralateral lung field and is often difficult to listen in a noisy operation room, it is often difficult to determine the depth by auscultation method. Pleural sliding sign, or sliding lung sign is a ultrasonographic finding that the visceral pleura moves against the parietal pleura. It is used to identify whether the lung is ventilated by ultrasound. The investigators are trying to use this pleural sliding sign to determine the depth of endotracheal tube, and compare this method with auscultation method.