There are two neuromuscular blocking agents that have short enough onset times to be used in rapid sequence intubation and induction: succinylcholine and rocuronium.
Onset and Duration
Succinylcholine’s time of onset of paralysis is 45 to 60 seconds and a duration of action of 6 to 10 minutes. Rocuronium has a time of onset of 45 to 60 seconds with a duration of action of approximately 45 minutes. Because of the longer duration of action, rocuronium is generally not recommended when prolonged neuromuscular blockade is not needed or less desired - such as in cases where the clinician will need to obtain or repeat a neurological exam in a timely manner (traumatic brain injuries, strokes, intracranial hemorrhages, etc.).
Succinylcholine has a much faster duration of action over rocuronium making it desirable in those neurological cases mentioned above, however, there are some side effects and contraindications to consider.
Adverse Effects and Contraindications
Succinylcholine is absolutely contraindicated in patients with a history of strong family history of malignant hyperthermia and in those patients who are at risk for severe hyperkalemia.
Determining the patients at risk for severe hyperkalemia can be determined by suggestive findings on electrocardiography, or when history suggests at risk pathology or at-risk medical history. For example, fatal cases of hyperkalemia have occurred in patients with rhabdomyolysis given succinylcholine. Also pathologies that cause upregulation of acetylcholine receptors, increases the risk of severe hyperkalemia from succinylcholine in susceptible patients. Receptor upregulation can take several days to develop, but once it is present hyperkalemia develops within a few minutes after succinylcholine is given. Because of these risks, succinylcholine is not recommended in the following clinical scenarios:
- Malignant hyperthermia history (personal or family)
- Neuromuscular disease
- Muscular dystrophy
- Stroke over 72 hours old
- Rhabdomyolysis
- Burn over 72 hours old
- Significant hyperkalemia (eg, suggested by characteristic changes on an electrocardiogram)
Succinylcholine and bradycardia
Succinylcholine causes nicotinic activation that manifests as muscle fasciculations, along with muscarinic stimulation that may lead to bradycardia in selected patients. Bradycardia in children is of particular importance because of the attribution of succinylcholine in causing the bradycardia, although data on this is controversial. Pretreatment with atropine may help to prevent this side effect, although no large randomized trials have been performed to assess this
The ICU Book
A fundamental and respected resource in critical care. Including a review of various common critical care pathology, ariway and mechnical ventilation.
Indications and Contraindications to Rapid Sequence Intubation
Indications for RSI are simply those patients who cannot ventilate, oxygenate or fail to protect their aiway. Contraindications are few and relative.
Seven P's of RSI - The Process of Rapid Sequence Intubation
RSI involves the use of an induction agent, followed immediately by a neuromuscular blocking agent to quickly create an optimal environment for intubation.