Posted on March 15, 2015 in: Innovative Practice
by Trevor Warner, Pharm.D., clinical pharmacist, Munson Medical Center
Pharmacy practice in health-systems has progressed significantly over the years, as pharmacists have become more involved in bedside care. The emergency department (ED) is one area where pharmacists have the unique opportunity to be closely involved with the interdisciplinary team at the patient’s bedside. Rapid sequence intubation (RSI) is a prime example of where a pharmacist’s drug expertise can prove invaluable to patient care in the ED. RSI is a process that can be emergent or nonemergent and involves the administration of a sedative induction agent and a paralytic to facilitate endotracheal intubation. Due to the often chaotic and emergent nature of RSI in the ED, there exists the potential for error to occur. ED pharmacists can assist in the selection of appropriate medications, dosing, and preparation of the sedative and paralytic agents prior to RSI.
RSI consists of seven steps commonly referred to as the seven P’s: preparation, preoxygenation, pretreatment. paralysis with induction (sedation), protection of the airway and position, placement of the endotracheal tube and post-intubation management.
Pharmacists can be an integral part of pretreatment and paralysis with induction by identifying patients who need pretreatment, selecting appropriate doses and preparing the agents for administration. Pretreatment generally occurs three minutes prior to the administration of induction agents and paralytics. The purpose of pretreatment is to blunt the physiologic effects of intubation and attenuate any anxiety the patient may have. Intubation stimulates parasympathetic and sympathetic nerves located in the airway, which can result in systemic catecholamine release. This stimulation may result in increased heart rate, blood pressure and intracranial pressure (ICP). Intubation can also stimulate cough and lower airway reflexes leading to laryngospasm and/or bronchospasm. Common medications used in pretreatment include lidocaine, midazolam, fentanyl and atropine.
Lidocaine is used to suppress the cough reflex, which may help prevent any increases in ICP during RSI. This is especially desirable in patients who may have an elevated ICP on presentation such as patients with traumatic brain injury. Lidocaine may also play a role in preventing bronchospasm although the results of studies are conflicting. Lidocaine should be dosed at 1.5 mg/kg and given three minutes prior to intubation.
Fentanyl is another agent that can be used for pretreatment with the goal of decreasing the release of catecholamines during intubation. Usually dosed at 1-3 mcg/kg, fentanyl should be administered as a slow IV push over 30-60 seconds to avoid the rapid respiratory depression that can occur with rapid administration. Atropine, an antimuscarinic, is a third agent that is sometimes used as pretreatment if succinylcholine is used. Succinylcholine stimulates muscarinic receptors and can result in bradycardia, and atropine may be given in an attempt to mitigate that response. The muscarinic effects of succinylcholine are generally more dramatic in pediatric patients where atropine is used more commonly.
Induction therapy involves the use of a rapid-acting sedative to a general state of anesthesia. Sedatives should always be administered prior to neuromuscular blocking agents to prevent any psychological trauma to patients. Pharmacists can play a vital role in recommending the appropriate order of administration of RSI agents. Midazolam, etomidate and propofol are the three most commonly used induction agents in RSI. Midazolam is the most lipophilic benzodiazepine, giving it a rapid onset of 60-90 seconds when used at appropriate induction doses of 0.2-0.3 mg/kg.
While midazolam has the most rapid onset of any benzodiazepine, it is relatively slow compared to etomidate. Etomidate is the gold standard for induction in RSI with an onset of 10-15 seconds and short duration of 4-10 minutes when used at doses of 0.3 mg/kg. Propofol also has a rapid onset, although it can exhibit significant hemodynamic effects. Propofol decreases blood pressure through a reduction in preload, afterload and decreased contractility of the myocardium, which can be problematic in patients who are hemodynamically unstable. Propofol should be administered at doses of 1.5-2.5 mg/kg for RSI in normotensive, euvolemic patients.
After induction therapy has been administered and the sedative agents have been given appropriate time to take effect, neuromuscular blockers (NMBA) are administered to paralyze skeletal muscle and facilitate intubation. The depolarizing NMBA, succinylcholine, is the gold standard and is widely used in RSI. Succinycholine has a rapid onset of ≤ 45 seconds and short duration of approximately 10 minutes, making it an ideal agent for RSI. Succinycholine should be administered at a dose of 1.5 mg/kg. Succinylcholine can increase serum potassium, however, on average 0.5 mEq/L. In patients with a predisposition to hyperkalemia (burn injury, crush injury, severe infection, etc.) succinylcholine should be avoided. The non-depolarizing NMBAs (most commonly rocuronium and vecuronium) are an alternative to succinylcholine. Vecuronium has a slow onset of action at 2-3 minutes and duration of action 45-65 minutes, which limits its utility in emergent intubation. Rocuronium, however, has a faster onset of action of approximately 60 seconds and duration of action of 40-60 minutes, making it a more suitable substitute for succinylcholine. Rocuronium should be dosed at 0.6-1.2 mg/kg.
Pharmacists can play a significant role in RSI through assisting in proper drug selection, dosing and administration as well as preparation of RSI drugs and post-intubation sedation all while at the bedside. This provides pharmacists with the opportunity to become intimately involved with patient care and be a valuable asset to the ED team. For more detailed information, please see the listed references.
References available upon request from MPA office.