However, the difference lies in the fact that the induction drug and neuromuscular blocking agent are administered in rapid succession with no time allowed for manual ventilation.Commonly used hypnotics include thiopental, propofol and etomidate. The neuromuscular blocking agents paralyze all of the skeletal muscles, most notably and importantly in the oropharynx, larynx, and diaphragm. Opioids such as fentanyl may be given to attenuate the responses to the intubation process (accelerated heart rate and increased intracranial pressure). This is supposed to have advantages in patients with ischemic heart disease and those with brain injury (e.g. after traumatic brain injury or stroke). Lidocaine is also theorized to blunt a rise in intracranial pressure during laryngoscopy, although this remains controversial and its use varies greatly. Atropine may be used to prevent a reflex bradycardia from vagal stimulation during laryngoscopy, especially in young children and infants. Despite their common use, such adjunctive medications have not been demonstrated to improve outcomes. Positioning
Positioning involves bringing the axes of the mouth, pharynx, and larynx into alignment, leading to whats called the "sniffing" position. The sniffing position can be achieved by placing a rolled towel underneath the head and neck, effectively extending the head and flexing the neck. You are at proper alignment when the ear is inline with the sternum.As described by Brian Arthur Sellick in 1961, cricoid pressure (alternatively known as Sellicks maneuver) may be used to occlude the esophagus with the goal of preventing aspiration. Placement of tube
During this stage, laryngoscopy is performed to visualize the glottis.
Lidocaine – It is used to reduce the sympathetic response in those who have suspected raised intracranial pressure (ICP) or those who received succinylcholine which also causes increase ICP or those with underlying asthma that have bronchospasm. Administration of lidocaine can causes reduction in mean arterial pressure (MAP). The dosage is 1.5 mg/kg. This drug is metabolised by liver. The side effects are: hypotension, arrythmia (irregular heart beat). Lidocaine can further interact with other drugs such as amiodarone and monoamine oxidase inhibitor to cause hypotension, and dronedarone to cause arrhythmia. Induction agents
Administration of induction agents followed by neuromuscular blockade agents helps to achieve optimal conditions for intubation. Etomidate – It is an imidazole-derivative that stimulates GABA receptors. The dosage is between 0.2 and 0.6 mg/kg (commonly 20 to 50 mg doses). Dose reduction may be required in those with hypotension. Etomidate has minimal cardiovascular side effects, reduces intracerebral pressure (by reducing cerebral blood flow), and does not cause histamine release. It has quick onset of action, short duration of action, and undergoes hepatic elimination. Myoclonus, pain at the site of the injection, post-operative nausea and vomiting are common. It can also suppresses the production of cortisol and aldosterone. Ketamine – It is highly lipophilic and crosses the blood-brain barrier. It inhibits the binding of glutamine to N-Methyl-D-aspartic acid (NMDA) receptors in Thalamocortical radiations and limbic system, causing amnesia. Through the same blockade of NMDA receptor, ketamine is also effective as a painkiller.