Rapid Sequence Induction: Succinyl Choline vs Rocuronium After Pretreatment With Dexmedetomidine

Rapid sequence induction (RSI) is a well-established anesthetic procedure routinely used in emergency and trauma setting, and in elective situations when there is high risk of regurgitation/aspiration The ideal neuromuscular relaxant agent used for RSI should have a quick onset of action, which is a major advantage in trauma setting as it mitigates the risk of aspiration and desaturation when endotracheal intubation should be performed as early as possible. It also should have a quick offset to ensure that if trials at endotracheal intubation were unsuccessful, there would be quick neuromuscular recovery, with return to spontaneous breathing before the patient start desaturation. Moreover, it should have minimal cardiovascular or systemic side effects.

Typically, succinyl choline has been the neuromuscular agent of choice for RSI as it has the quickest onset and offset of action compared to other muscle relaxants. However, it has potentially risky- sometimes fatal- side effects that make it far from being ideal neuromuscular blocking agent in RSI.

Owing to its fast onset of action and stable hemodynamics Rocuronium, a non-depolarizing muscle blocker, has been suggested as possible alternative to succinyl choline in RSI. The standard rocuronium intubating dose of during routine anesthesia is 0.6 mg/ kg, which results in adequate intubation conditions within 60 seconds in nearly all patients.

The recommended rocuronium intubating dose during RSI anesthesia is 1.0-1.2 mg/kg, after which optimum tracheal intubation conditions are also achieved within 60 seconds in nearly all patients. If the standard dose of 0.6 mg/ kg is given on RSI of anesthesia, it is advised to wait 90 seconds before attempting to intubate the trachea.

Nevertheless, this high dose has long duration of action and may pose a risk in patients with unpredictable difficult intubation.

Dexmedetomidine (DEX), is a selective centrally acting α 2-adrenergic receptors agonist that has been used successfully as procedural adjuvant, e.g., to minimize the stress response to laryngoscopy during endotracheal intubation and has gained popularity in the peri-operative period, due to its unique action as anxiolytic, sedative with no respiratory depression, analgesic, opioid sparing effect, and Its ability to decrease overall anesthetic requirements.

The aim of our study is to compare a combination of standard intubating dose of DEX and rocuronium (0.6 mg /kg) to succinyl choline as regard endotracheal intubation condition during RSI.

Material and method

Patients will be randomly allocated to one of two groups, of 120 each. The Dex pretreatment/ rocuronium group (DR group), and saline pretreatment/succinyl group (SS group). In the DR group, patients shall receive pretreatment with Dex 1 µg / kg in 10 ml 0.9% saline over 10 minutes and rocuronium 0.6 mg/kg is the intubating muscle relaxant. In the SS group, patients receive pretreatment with 10 ml 0.9% saline over 10 minutes, and succinyl choline 1mg/ kg is the intubating muscle relaxant. Pretreatments will be given over 10 minutes using infusion pump.

As soon as the pretreatment is completed, intravenous (IV) fentanyl 0.1 μg / kg and preoxygenation for 3 minutes with a facemask, after which anesthesia is induced with IV propofol 2 mg/ kg. Standardized intubating procedure is carried out that on loss of consciousness, the neuromuscular relaxant drug is given per protocol, and 45 seconds later the intubating anesthetist will be called in the operating room, at 50 seconds laryngoscopy is introduced and at 60 seconds, the trachea would be expectedly successfully intubated. To minimize interobserver bias, all intubations will be conducted by two designated senior consultants. No ventilation will be carried out before orotracheal intubation. No cricoid pressure shall be performed.