“Neuromuscular blockade [using succinlycholine or rocuronium] is the cornerstone of rapid sequence intubation (RSI) optimizing conditions for tracheal intubation while minimizing the risks of aspiration or other adverse effects.” (1) The neuromuscular blocking agents (NMBAs) only paralyze the patient so it is critical to use a sedative-induction agent (etomidate or ketamine) along with the NMBA. And if neuromuscular blockadge is maintained post intubation it is critical that appropriate sedation is provided.
In the Airway Management book the authors state that “Succinylcholine (SCh) is the NMBA of choice for emergency RSI because of its rapid onset and relatively brief duration of action. A personal or family history of malignant hyperthermia is an absolute contraindication to the use of SCh. . . . . Certain conditions [burns, denervation, crush injuries, severe infections, inherited myopathies (including undiagnosed myopathies in pediatric patients), and pre-existing hyperkalemia], described in “Adverse Effects” [described on pp 258 +259 of the Airway Manual], place patients at risk for SCh-related hyperkalemia and represent absolute contraindication to SCh.“
The recommended dose of succinlycholine in adults is 1.5 mg per kg dosed on the total body weight.
“In children younger than 10 years, length-based dosage is recommended, but if weight is used as the determinant, the recommended dose of SCh for emergency RSI is 2 mg per kg IV, and in newborn (younger than 12 months), the appropriate dose is 3 mg per kg IV.”
“In 1993, the U.S. Food and Drug Administration (FDA), in conjunction with pharmaceutiacal companies, revised the package labeling for SCh in the wake of reports of hyperkalemic cardiac arrest following the administration of SCh to patients with previously undiagnosed neuromuscular disease. Initially, it stated that SCh was contraindicated for elective anesthesia in pediatric patients because of this concern, although the wording was subsequently altered to embrace a risk-benefit analysis when deciding to use SCh in children. However, both the initial advisory warning and the revised warning continue to recommend SCh for emergency or full-stomach intubation in children.” (3)
Succinylcholine can cause bradycardia and so atropine needs to be available.
“On occasion, SCh may cause transient trismus/masseter muscle spasm, especially in children. This manifests as jaw muscle rigidity associated with limb muscle flaccidity. . . . If masseter muscle spasm interferes with intubation, an intubating dose of a competitive nondepolarizing agent (e.g., rocuronium 1 mg per kg [IV] should be administered and will relax the involved muscles. Masseter spasm should prompt serious consideration of the diagnosis of Malignant Hyperthermia.”
In the US and Canada, the emergency malignant hyperthermia hotline is 1-800-644-9737 and ask for “index zero”. Many excellent resources, including free CME, are available at the Malignant Hyperthermia Association website at www.mhaus.org.
Succinlycholine can cause prolonged neuromuscular blockade (paralysis) in patients with an acquired pseudocholesterase deficiency (“from liver disease, cocaine abuse, pregnancy, burns, oral contraceptives, metoclopramide, bambuterol, or esmolol”) and in patients with congenital pseudocholesterase absence or abnormality.
Rocuronium (as well as vecuronium and pancuronium) are nondepolarizing or competitive NMBAs.
The dose of rocuronium is 1 mg per kg and the time to an intubation level of paralysis is 60 seconds. The duration of paralysis is 40 to 60 minutes and rocuronium is pregnancy category B.
“Rocuronium, 1 mg per kg IV, is the drug of choice when succinlycholine is contraindicated.”
“The only contraindication to a competitive NMBA [e.g., rocuronium] is known prior anaphylaxis to that agent.”
“For postintubation management when continued neuromuscular blockade is desired, vecuronium 0.1 mg per kg IV or pancuronium 0.1 mg per kg IV is appropriate, in concert with adequate sedation.”
(1) Manual of Emergency Airway Management 4th ed, 2012. RM Walls and MF Murphy, p 255.
(2) Ibid., pp 255-259.
(3) Ibid., p 281.
(4) Ibid., pp 260+261.