Association of Oro-tracheal tube inserted depth with anatomi-cal parameters among infants

:  Endotracheal intubation is a common procedure done in infants and neonates requiring respiratory support. More often this procedure is done in emergency setting, where predicting data such as weight of the patient may not be easy. After intubation, it is a standard medical practice to confirm the clinically effective position of the tip of the ET tube initially by chest auscultation and later by EtCO2. Optimal Endotracheal (ET) tube positioning is important, and the ideal position is halfway between vocal cord and carina. If an ET tube is placed too high accidental extubation may occur, if placed too low then endobronchial intubation, poor ventilation, atelectasis or pneumothorax may occur. The initial clinical assessment of the appropriate intubation depth is to auscultate equal  air entry to the bilateral lungs. Nevertheless, it lacks a quantitative or qualitative change of breathing sound detected on auscultation, despite 1cm downward displacement of the ET tube tip into the main bronchus; one study indicated that up to 60% of endobronchial intubations were by equal breath sound auscultation. Thus, several methods have been reported to determine the proper ET tube depth for  intubation and the accurate ET tube tip position, such as the well-known 7-8-9 Rule, body parameters as a predictor, the manufacturer’s markings on the tube tip and sonogram. Also, a number of nomograms are available to predict this depth from external body measurements such as weight, head circumference, crown-heel or crown-rump length. However, many of these studies have their limitations.