Among others, the role of lidocaine given intravenously, topically, or intracuff has been studied. Intracuff lidocaine has been shown to increase the tolerance to the endotracheal tube without reducing the swallowing reflex. However, lidocaine slowly diffuses across the tube's cuff. The addition of bicarbonates is required to increase its diffusion to the underlying tracheal tissue. Alkalinization of lidocaine allows the diffusion of 65% of its neutral base form over a period of 6 hours.