What is the role of pretreatment medications prior to rapid sequence intubation (RSI)?

Updated: Apr 07, 2020
  • Author: Keith A Lafferty, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Answer

Pretreatment agents may be used to mitigate the physiologic response to laryngoscopy and induction and paralysis, which may be undesirable in certain clinical situations.  Note though clinical dogma has supported their use in the past, evidence in the literature is deficient in this area and because of this, these are mentioned from a historical perspective. 

Pretreatment medications are typically administered 2-3 minutes prior to induction and paralysis. These medications can be remembered by using the mnemonic LOAD (ie, Lidocaine, Opioid analgesic, Atropine, Defasciculating agents).

Lidocaine (1.5 mg/kg IV) may suppress the cough or gag reflex experienced during laryngoscopy and has been considered to play a role in blunting increases in mean arterial pressure (MAP), heart rate (HR), and intracranial pressure (ICP). For this reason, it is commonly administered to patients with suspected intracranial hemorrhage, tumor, or any other process that may result in increased ICP, and it may be considered as part of RSI for patients in whom increased MAP could be harmful (eg, leaking aortic aneurysm). However, studies do not consistently demonstrate the effectiveness of lidocaine for these indications in patients in the emergency department (ED), and, based on this lack of evidence, a statement regarding its absolute indication cannot be made. [8, 18, 19, 20, 21, 22, 23, 24, 25, 26]

Opioid analgesic (fentanyl 3 mcg/kg IV) mitigates the physiologic increase in sympathetic tone associated with direct laryngoscopy (ie, blunts increases in blood pressure, heart rate, and mean arterial pressure). One author recommends this in patients with suspected high ICP, [27, 28, 29] though some data also suggest that these agents may increase ICP. [30, 31, 32, 33, 34, 35] Opioid analgesics may also be useful in patients with an aortic emergency (eg, aortic dissection or leaking aortic aneurysm) in whom blood pressure spikes should be avoided. At this time, no conclusive evidence supports the use of opioids in RSI.

Atropine (0.02 mg/kg IV) may decrease the incidence of bradydysrhythmia associated with direct laryngoscopy (stimulation of parasympathetic receptors in the laryngopharynx) and administration of succinylcholine (direct stimulation of cardiac muscarinic receptors). Previous recommendations indicated that all children younger than 10 years receive atropine prior to intubation, but this has fallen out of favor because of the lack of supporting data. Even if bradydysrhythmias occur, they are usually self-limited and clinically nonrelevant. However, atropine should be available in case a clinically significant decrease in heart rate occurs. Because of the increase in cardiac vagal tone, atropine can be considered for use in children younger than 1 year and should at least be at the bedside in this age group. [36, 37] Some evidence indicates that bradycardia can occur equally with or without atropine during intubation. [36, 38] Atropine can also be used in adolescents and adults for symptomatic bradycardia.

A "defasciculating" dose of a nondepolarizing agent may reduce the duration and intensity of muscle fasciculations observed with the administration of succinylcholine (due to the stimulation of nicotinic acetylcholine receptors). The recommended dose is 10% of the paralyzing dose (eg, 0.01 mg/kg for vecuronium). Equivocal studies suggest such pretreatment may help reduce increases in intracranial pressure related to the procedure.

Some practitioners bypass the pretreatment phase and go straight to induction agents. The exception is that some still administer opioids, but in conjunction with the induction agent and not as pretreatment.

The crux of RSI is to take the awake patient, with an assumed full stomach, and very quickly induce a state of unconsciousness and paralysis and securing the airway. This is done without positive-pressure ventilation, if possible.


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