This study aims to compare the accuracy of measurement between ultrasonography and Cole formula in predicting uncuffed endotracheal tube diameter.

Approval from Ethical Committee of Faculty of Medicine Universitas Indonesia was acquired prior conducting the study. Subjects were given informed consent before enrolling the study. Non-invasive blood pressure (NIBP) monitor, ECG and pulse-oximeter was set on the subjects in the operation room. The uncuffed endotracheal tube (ETT) diameter predictions were measured firstly using ultrasonography (USG), then with Cole formula. After that, polyvinyl chloride (Mallinckrodt) ETT intubation with Cole diameter measurement was inserted using direct laryngoscopy. If the ETT was too small, use a 0.5 mm bigger ETT than the prediction diameter, if it too big, use a 0.5 mm smaller ETT than the prediction diameter. Reintubation and measurements using both methods were recorded. If bradycardia or desaturation happened, positive pressure ventilation, 100% oxygen, atropine 0,01-0,02 mg/kg, adrenaline 0,01 mg/kg could be given. Data was analyzed using SPSS using Bivariat Chi-square test or Fisher Exact Test (categorical comparative analytical study).

Inclusion Criteria:

• Subjects aged 1-6 years old, Malayan race, planned to undergo elective surgery with general anesthesia with intubation
• Subjects with ASA status I-II
• Cooperative subjects
• Subjects whose parents had signed the informed consent

Exclusion Criteria:

• Subjects with allergies to Ultrasonography jelly
• Subjects with difficult airway
• Subjects with mass in the neck area
• Subjects with respiratory diseases
• Subjects with growth & development disorders
• Subjects with malnutrition (<5% percentile) and obesity (>95% percentile).

Drop out criteria:

• Subjects with cardiorespiratory disorder during intubation
• Subjects who were failed to be intubated twice.