Specialist, Department of Anaesthesiology, Corniche Hospital, Abu-Dhabi, UAE Abstract Rapid sequence induction-intubation and cricoid pressure – facts and fallaciesĮmail: Professor, Department of Anaesthesiology, Kasturba Medical College, Manipal, India They might also modify the sequence of drugs for RSI or develop a more detailed backup plan in case of failed intubation.Indian Journal of Respiratory Care Volume 3 | Issue 1 | Year 2014 If the preintubation examination predicts a difficult airway, the clinician may select an alternative method to RSI. The most common reason why nondepolarizing NMBAs shouldn't be used for RSI is when the airway is predicted to be difficult. The time it takes to reach intubation-level paralysis is approximately 45 to 60 seconds, with a duration of action lasting around 45 minutes. A higher dose usually results in more consistent paralysis and allows for easier laryngoscopy due to the added mechanical advantage of having the patient completely paralyzed from the start. The recommended dose for this neuromuscular blocking agent (NMBAs) is 1.5 mg/kg, given intravenously (IV), according to the patient's total body weight (except in myasthenia gravis where a lower dose of 0.6 mg/kg IV should be used). The other agent that has a rapid onset is rocuronium which is a nondepolarizing neuromuscular blocking agent (NMBAs). These conditions constitute denervating diseases (eg, multiple sclerosis, amyotrophic lateral sclerosis), inherited myopathies (eg, Duchenne muscular dystrophy), burns, after 72 hours, crush injuries after 72 hours, rhabdomyolysis, prolonged total body immobilization and severe, prolonged intraabdominal infections. SCh is contraindicated in malignant hyperthermia, hyperkalemia, and in conditions that upregulate the ACh receptors and increase the risk of hyperkalemia. Given as a 1.5 mg/kg intravenous (IV) dose (except in myasthenia gravis where a higher dose at 2 mg/kg IV should be used), paralysis sets in 45 to 60 seconds after dosing for rapid sequence intubation and generally lasts for 6 to 10 minutes. SCh is commonly used in emergency settings because it works rapidly and provides dependable intubating conditions. This leads to muscle fasciculations followed by paralysis. SCh binds directly to the postsynaptic ACh receptors on motor endplates, causing continuous stimulation of these receptors. ![]() ![]() The depolarizing agent succinylcholine (SCh) is an analog of acetylcholine (ACh). Ketamine has a time to effect of 45 to 60 seconds, and a duration of action of 10 to 20 minutes. In patients with hypertension or when ICP elevation is suspected, ketamine should be avoided as it can worsen blood pressure. The RSI induction dose of ketamine is 1 to 2 mg/kg IV. If a patient has already maximally activated the sympathetic response and depleted all of their reserve (for example, patients in profound hypovolemic shock), administering ketamine may cause them to experience low blood pressure. However, it is only possible to stimulate the sympathetic nervous system with ketamine if there is enough sympathetic reserve. For this reason, ketamine may be a better choice than etomidate for patients who are at risk of hypotension. It has mild direct cardiovascular effects, but in patients with an intact autonomic nervous system, ketamine can actually cause sympathetic stimulation and an increase in blood pressure, heart rate, and cardiac output. Ketamine works by blocking NMDA receptors. We will now go over the three most typical induction agents-etomidate, ketamine, and propofol-and discuss their possible side effects and the best clinical setting for each agent. The length of time it takes for the drugs to take action after administration varies depending on which agent is selected, but regardless, our objective is to achieve adequate sedation and paralysis in 45-60 seconds. Instead, we calculate the dose of each agent ahead of time to get the desired effect. RSI does not entail titration of these agents to reach this state. ![]() We choose agents for paralysis and induction with the intent of causing unconsciousness and full muscle relaxation rapidly. Therefore, the choice of induction medication should be done carefully to minimize these risks and cardiovascular status should be optimized with crystalloids, blood products, vasopressors, or inotropes before beginning RSI. Although RSI is associated with less rate of complications, however, patients who are critically ill may experience hypotension as a result of the rapid induction.
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