 Originally made from latex rubber , most modern endotracheal tubes today are constructed of polyvinyl chloride . Tubes constructed of silicone rubber , wire @-@ reinforced silicone rubber or stainless steel are also available for special applications . For human use , tubes range in size from 2 to 10 @.@ 5 mm ( 0 @.@ 1 to 0 @.@ 4 in ) in internal diameter . The size is chosen based on the patient 's body size , with the smaller sizes being used for infants and children . Most endotracheal tubes have an inflatable cuff to seal the tracheobronchial tree against leakage of respiratory gases and pulmonary aspiration of gastric contents , blood , secretions and other fluids . <unk> tubes are also available , though their use is limited mostly to children ( in small children , the cricoid cartilage is the narrowest portion of the airway and usually provides an adequate seal for mechanical ventilation ) . 
