Editing Rapid sequence induction (section)

==== Induction agents ====
Administration of induction agents followed by neuromuscular blockade agents helps to achieve optimal conditions for intubation.<ref name="Joanna 2014"/>
* [[Etomidate]] – It is an [[imidazole]]-derivative that stimulates GABA receptors. The dosage is between 0.2 and 0.6&nbsp;mg/kg (commonly 20 to 50&nbsp;mg doses). Dose reduction may be required in those with [[hypotension]].<ref name=":4">{{cite journal | vauthors = Arteaga Velásquez J, Rodríguez JJ, Higuita-Gutiérrez LF, Montoya Vergara ME | title = A systematic review and meta-analysis of the hemodynamic effects of etomidate versus other sedatives in patients undergoing rapid sequence intubation | journal = Revista Espanola de Anestesiologia y Reanimacion | pages = 663–673 | date = October 2022 | volume = 69 | issue = 10 | pmid = 36241514 | doi = 10.1016/j.redare.2021.05.020 | s2cid = 252857226 }}</ref> Etomidate has minimal cardiovascular side effects, reduces intracerebral pressure (by reducing cerebral blood flow), and does not cause histamine release.<ref name=":4" /> It has quick onset of action, short duration of action, and undergoes hepatic elimination.<ref>{{cite book | vauthors = Williams LM, Boyd KL, Fitzgerald BM | chapter = Etomidate |date=2022 | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK535364/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30570985 }}</ref> [[Myoclonus]], pain at the site of the injection, post-operative nausea and vomiting are common.<ref name=":5">{{cite journal | vauthors = Lang B, Zhang L, Yang C, Lin Y, Zhang W, Li F | title = Pretreatment with lidocaine reduces both incidence and severity of etomidate-induced myoclonus: a meta-analysis of randomized controlled trials | language = English | journal = Drug Design, Development and Therapy | volume = 12 | pages = 3311–3319 | date = 2018-10-04 | pmid = 30323563 | pmc = 6174893 | doi = 10.2147/DDDT.S174057 | doi-access = free }}</ref> While common, the incidence and severity myoclonus can be reduced with pretreatment lidocaine without affecting hemodynamic stability of the patient.<ref name=":5" /> A rare but serious potential complication is that etomidate can also suppresses the production of [[cortisol]] and [[aldosterone]].<ref name="Joanna 2014"/>
* [[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. The dosage is 1 to 2&nbsp;mg/kg, usually given at 100&nbsp;mg. Ketamine is metabolized by liver and excreted through kidneys.<ref>{{cite book | vauthors = Rosenbaum SB, Gupta V, Patel P, Palacios JL | chapter = Ketamine |date=2022 | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK470357/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29262083 |access-date=2022-11-02 }}</ref> The drug lessen the reuptake of the [[catecholamine]], increases heart rate, blood pressure, and cardiac output, thus suitable for those with hypotension.<ref name=":6">{{cite journal | vauthors = Baekgaard JS, Eskesen TG, Sillesen M, Rasmussen LS, Steinmetz J | title = Ketamine as a Rapid Sequence Induction Agent in the Trauma Population: A Systematic Review | journal = Anesthesia and Analgesia | volume = 128 | issue = 3 | pages = 504–510 | date = March 2019 | pmid = 29944524 | doi = 10.1213/ANE.0000000000003568 | s2cid = 49427767 | doi-access = free }}</ref> However, it can worsen the cardiac depression and hypotension for those with depletion of catecholamines.<ref name=":6" /> Thus, maximum dose of 1.5&nbsp;mg/kg is need for this situation. For those with head injuries, ketamine does not appear to increase intracranial pressure, while able to maintain the mean arterial pressure.<ref name=":6" /> Ketamine also relieves bronchospasm by relaxing bronchiolar smooth muscles. However, it increases oral secretions during intubation. Ketamine is associated with nightmares, delirium, and hallucinations.<ref name="Joanna 2014"/>
* [[Propofol]] – It is a highly lipid-soluble, [[Γ-Aminobutyric acid|GABA]] agonist.<ref name=":7">{{cite book  | vauthors = Folino TB, Muco E, Safadi AO, Parks LJ | chapter = Propofol |date=2022 | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK430884/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=28613634 |access-date=2022-11-02 }}</ref> The dosage is 1.5&nbsp;mg/kg (usually 100 to 200&nbsp;mg). It has quick onset of action, can cross the [[Blood–brain barrier|blood-brain barrier]], wide tissue distribution, and can be hepatically cleared by the body quickly.<ref name=":7" /> In  the elderly, the rate of Propofol clearance is low. Therefore, lower doses of Propofol (50 to 100&nbsp;mg) should be given. It is suitable in those with kidney or liver impairment and decreases intra-cranial pressure. For those with bronchospasm, Propofol also has mild bronchodilating effect.<ref name=":7" /> However, Propofol can induce hypotension and bradycardia due to its [[calcium channel blocker]] and [[beta blocker]] properties.<ref name=":7" /> At prolonged high Propofol dosages, it can induce [[Propofol infusion syndrome]], characterized by acute refractory [[bradycardia]] leading to [[asystole]] accompanied by one of the following: [[rhabdomyolysis]], acute [[Fatty liver disease|fatty liver]] or enlarged liver, and [[metabolic acidosis]].<ref>{{cite journal | vauthors = Kam PC, Cardone D | title = Propofol infusion syndrome | journal = Anaesthesia | volume = 62 | issue = 7 | pages = 690–701 | date = July 2007 | pmid = 17567345 | doi = 10.1111/j.1365-2044.2007.05055.x | s2cid = 16370071 }}</ref> Pain during peripheral administration of Propofol can be reduced by using pretreatment lidocaine or a large bore [[peripheral venous catheter|cannula]].<ref name="Joanna 2014"/>
* [[Midazolam]] – Apart as a premedication, midazolam can be used as an induction agent at the dose of 0.2 to 0.3&nbsp;mg/kg.<ref name=":3" /> It has slow onset of action when used alone, but the onset can be improved when using together with an opioid.<ref name=":3" /> However, for those with hypotension, midazolam can further reduce the blood pressure and has cardiac depressive effects.<ref name=":6" /> Therefore, dose reduction is required for the elderly, and for those with heart and liver failure.<ref name="Joanna 2014"/>
* [[Methohexital]] – This is a barbiturate drug that works as a GABA agonist, reducing the dissociation of GABA A from its receptors.<ref name=":8">{{Citation |last1=Syed |first1=Qaisar |title=Methohexital |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK544291/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31335011 |access-date=2022-11-10 |last2=Kohli |first2=Arpan}}</ref> The dosage is 1.5&nbsp;mg/kg. It is metabolized in liver. However, methohexital can cause respiratory depression, laryngospasm, venodilatation, myocardial depression, and hypotension. Additionally, it can also cause reduced cerebral blood flow and histamine release. It can cause distal thrombosis and tissue necrosis if given into the arterial system.<ref name="Joanna 2014"/> This drug is commonly associated with pain when given through small peripheral veins.<ref name=":8" /> This can be prevented by dissolving the drug into a lipophilic mixture without reducing the potency of the drug.<ref name=":8" />