Chapter 10. Rapid Sequence Induction

Rapid sequence induction (RSI) of anesthesia, sometimes referred to as “crash” induction, has become a safe and effective method of establishing emergent airway control in patients with suspected life-threatening emergencies. It ensures optimal patient compliance in a well-controlled environment. RSI involves the near simultaneous administration of a potent sedative–hypnotic agent and a neuromuscular blocking agent.1–20 Various pretreatment drug regimens have been advocated to prevent potentially deleterious side effects, such as aspiration of gastric contents, cardiovascular excitation or depression, and intracranial pressure elevation.

The first endotracheal tubes were developed for the resuscitation of the newborns and victims of drowning in the nineteenth century, but were not used in anesthesia until 1878.13 Muscle relaxants were not prepared until some 60 years later. Succinylcholine was prepared by the Nobel Laureate Daniel Bovet in 1949, after which it gained the widespread usage it still enjoys today. The RSI technique did not come into modern day practice until the end of World War II.

Patients can be hypoxic, confused, uncooperative, unstable, and unknowing of their medications or medical conditions and can require airway control within minutes of arrival at the Emergency Department. RSI is the preferred method for securing the airway in the Emergency Department, as these patients are at risk for aspiration. These risks include vomiting from gastrointestinal obstruction, opioids, or hypotension; regurgitation from diabetic gastroparesis, gastroesophageal reflux, increased gastric pressure, or decreased lower esophageal sphincter tone; impaired laryngeal protective reflexes; and difficult airway management.7 Conditions such as recent meal ingestion, pain, obesity, and pregnancy place patients at higher risk as well.

The primary indication for RSI is to quickly protect and secure the patient's airway. The rationale behind RSI is to create an environment in which the trachea can be intubated as quickly and with as little difficulty as possible. The clinical conditions occurring at the time of attempted intubation are therefore of great importance. During RSI, the drugs used to produce hypnosis and muscle relaxation interact together to produce the intubating conditions. A complete list of the indications for RSI appears in Table 10-1.

There are few contraindications to RSI. It should not be performed by an inexperienced intubator. If the physician has doubts about his or her ability to intubate the patient, an awake intubation should be considered. The unavailability of equipment, contraindications to muscle relaxants, and critically ill patients in whom the airway can be secured by other methods (fiberoptic intubation, topical anesthesia, or minimal sedation with a benzodiazepine and/or narcotic) are also contraindications to RSI. Any contraindication to the use of succinylcholine is also a contraindication to RSI. Table 10-2 lists the many common contraindications to the use of succinylcholine. Patients in cardiopulmonary arrest do not require RSI as they should not have any muscle tone to overcome. A relative contraindication is a patient in whom bag-valve-mask ventilation is difficult or anticipated to be difficult.

• Supplemental oxygen with appropriate tubing and connectors
• Laryngoscope handle with extra batteries
• Laryngoscope blades, various sizes and types
• Endotracheal tubes, various sizes
• Wire stylet, malleable type
• Nonrebreather oxygen masks, various sizes
• Oropharyngeal airways, various sizes
• Nasopharyngeal airways, various sizes
• Alternative airway devices
• Suction source with appropriate tubing
• Suction catheters for endotracheal tubes
• Yankauer suction catheter
• Bag-valve-mask devices, various sizes
• Face masks, various sizes
• Stethoscope
• Water-soluble lubricant or anesthetic jelly
• Tape
• Benzoin adhesive
• Syringes, 10 and 20 mL
• Medications drawn up and labeled
• Pulse oximeter
• Cardiac monitor
• Automatic sphygmomanometer
• End-tidal carbon dioxide (CO2) monitor/device
• Crash cart
• Resuscitation medications
• Personnel (respiratory technician, medication nurse, recorder, in-line stabilization assistant)

The equipment required for RSI is the same as that for any intubation.10,13 Complete details regarding the selection of properly sized equipment can be found in Chapters 7 and 11. In addition, backup equipment should be readily available if the patient cannot be intubated. This can be a laryngeal mask airway, a cricothyroidotomy tray, a retrograde guidewire kit, or a percutaneous jet ventilation system to name a few.

RSI can be performed with little or no preparation. If possible, a few steps can be performed while the patient is being evaluated. Administer supplemental oxygen to the patient with a nonrebreather mask. Apply a noninvasive blood pressure cuff, continuous pulse oximetry, and cardiac monitoring. Obtain intravenous access. If time permits, pharmacologic agents can be used to increase gastric pH and motility (antacids, H2 receptor blockers, and metoclopramide). An antisialagogue (atropine or glycopyrrolate) may also be administered to decrease excessive oral and respiratory tract secretions.

Evaluate the airway (Chapter 6). If, after evaluation of the airway, there is sufficient doubt as to the possibility of intubating the patient successfully, a neuromuscular relaxant should not be administered. Consideration should be given to securing the airway in another fashion (e.g., awake intubation).

The three main characteristics of RSI are preoxygenation, application of cricoid pressure, and the avoidance of positive pressure ventilation (if possible) prior to securing the airway with a cuffed endotracheal tube. In addition, RSI requires the presence of ancillary equipment and experienced assistance. The details of timing, drug choice, and dosage are not rigidly defined. A RSI protocol is described below from start to finish.

Preoxygenate the patient with 100% O2 by a nonrebreather mask, or ventilate with a bag-valve-mask device using cricoid pressure. This will build an oxygen reserve and prevent hypoxemia during induction. Traditionally, preoxygenation for 5 minutes is the routine practice. If this is not practical, attempt to preoxygenate the patient for 3 minutes.6 However, four maximal inspirations are equally effective in the cooperative patient.6 Oxygen administration via noninvasive positive pressure ventilation can improve oxygenation more rapidly than by a face mask.21

While an assistant is preoxygenating the patient, evaluate the airway to anticipate any difficulties during the intubation (Chapter 6). Assemble all required equipment. Connect the bag-valve device to a mask and an oxygen supply. Lubricate and place the malleable stylet into the endotracheal tube. Attach a syringe to the inflation port of the endotracheal tube cuff. Inflate the cuff to look for any air leaks. Deflate the cuff and leave the syringe attached to the inflation port. Attach the laryngoscope blade to the handle and make sure that the light is functional. Simultaneously, the nurses should apply a noninvasive blood pressure cuff, continuous pulse oximetry, and cardiac monitoring to the patient. They should also draw up and label the required medications, establish intravenous access, set up the suction, record all events, and continuously observe the noninvasive blood pressure readings, cardiac monitor, and pulse oximeter.

If there is no suspicion of a cervical spine injury, position the patient in the optimum “sniffing” position. If there is suspicion of a cervical spine injury, an assistant should provide manual in-line axial stabilization of the head and neck during the intubation sequence and remove the anterior aspect of the cervical spine collar to allow for maximal mouth opening and access to the neck.

Premedicate the patient (Table 10-3). The mnemonic “LOAD” has been used to indicate the pretreatment drugs for RSI.15 The mnemonic stands for lidocaine, opioid (specifically, fentanyl), atropine, and defasciculation. Lidocaine (1.0 to 1.5 mg/kg) can be given to blunt the intracranial pressure response, transient hypertension, bronchospasm, and tachycardia associated with intubation. Fentanyl (2 to 3 μg/kg) or one of its derivatives can be given to also blunt the intracranial pressure response, transient hypertension, and tachycardia associated with intubation. Atropine (0.01 to 0.02 mg/kg, minimum 0.1 mg, maximum 1.0 mg) should be given to children less than 1 year old to prevent bradycardia in response to direct laryngoscopy. Administer a defasciculating dose of a nondepolarizing neuromuscular blocking agent. This is one-tenth of the intubating dose (Table 10-4). Phenylephrine (50 μg) can be given to attenuate the hypotensive response to intubation. Administer an appropriate induction agent as indicated by the clinical setting and patient's hemodynamic status (Tables 10-5 and 10-6). Flush the intravenous line with 5 to 10 mL of 0.9% normal saline solution after each drug to ensure delivery.

Administer a neuromuscular blocking agent.1,2,5 Numerous agents are available (Table 10-4). The most commonly used medications are succinylcholine (1.0 to 1.5 mg/kg) or rocuronium (1.0 to 1.2 mg/kg). Succinylcholine is the preferred agent. Its effects are short lasting (4 to 6 minutes). This is especially useful if the patient cannot be intubated, as they will need to be ventilated with a bag-valve-mask device until the succinylcholine wears off. Rocuronium allows the same intubating conditions as succinylcholine except that it lasts for 30 to 60 minutes. This is problematic if the patient cannot be intubated.

An assistant should apply cricoid pressure as soon as the patient loses consciousness and maintain it until successful oral endotracheal intubation has been confirmed. Avoid mask ventilation if possible. If hypoxemia or hypercarbia ensues, begin mask ventilation to a maximum pressure of 20 cmH2O while maintaining cricoid pressure.

Intubate the trachea 60 to 90 seconds after the succinylcholine (or rocuronium) has been administered and the patient's muscles are relaxed, as noted by apnea and jaw relation. Confirm the correct position of the endotracheal tube by visualizing the tube passing through the vocal cords, observing sustained presence of end-tidal CO2 on the capnograph, and auscultating breath sounds at the midaxillary lines.11,12 Auscultate over the epigastric area to ensure that ventilation is not audible over the stomach. Release cricoid pressure. If indicated, administer a long-acting paralytic agent (Table 10-4). After successful intubation, administer additional sedative hypnotics and analgesics as dictated by clinical needs. Obtain a chest radiograph to confirm proper placement of the endotracheal tube.

Special Considerations in Pediatric Patients

Rapid sequence induction is often used in the Emergency Department for securing the airway of pediatric patients. The indications and equipment, except for being smaller, are essentially not different than in the adult patient. Infants and young children have developmental differences in head and neck anatomy (Chapter 6). These differences make the Miller blade the preferred laryngoscope blade for intubation in this group. Infants and young children have a higher volume of distribution, which is why they require different doses of induction agents as reflected in Tables 10-4 & 10-5.

Preoxygenation is particularly important for infants and children. Compared with adults, these young patients have a higher oxygen consumption rate and a lower functional residual capacity. Consequently, oxygen desaturation occurs much more rapidly. If the child is desaturating or apneic, careful bag-mask ventilation with small tidal volumes (while maintaining cricoid pressure) should be performed to achieve adequate preoxygenation.

The use of succinylcholine remains controversial in pediatrics. Rapid sequence induction and laryngospasm are perhaps the last remaining indications for the use of succinylcholine in pediatrics. In 1994, the US Food and Drug Administration (FDA) recommended that the use of succinylcholine in children be reserved for emergency intubation and instances where the immediate securing of the airway is necessary due to the risks of hyperkalemia. This includes patients with laryngospasm, difficult airways, full stomachs, or for intramuscular use. If a child has no vascular access, succinylcholine (4 mg/kg) can be administered intramuscularly. It will provide a maximum onset of blockade in 3 to 4 minutes and last approximately 20 minutes. If there is a contraindication to using succinylcholine, rocuronium can be used for RSI. Children between 2 and 12 years old require more rocuronium than adults. The recommended doses are 0.9 to 1.2 mg/kg in this age group.

Atropine is commonly used in young children. Atropine (20 μg/kg) administered as a premedication is indicated in all children<1 year old and in all ages if a second dose of succinylcholine is required to intubate the patient.19 There is a risk of bradycardia with the use of succinylcholine in children. This can be attenuated by premedicating the patient with atropine (20 μg/kg) or glycopyrrolate (10 μg/kg).20

Confirm that endotracheal intubation is successful. This includes auscultation, fogging of the endotracheal tube with ventilations, as well as presence of persistent end-tidal CO2. End-tidal CO2 can be confirmed using a capnograph or a chemical (colorimetric) indicator device that consists of a pH-sensitive indicator where the dye changes its color in the presence of CO2. A minimum of six breaths should be administered before a determination is made regarding successful endotracheal intubation. This will eliminate false-positive readings obtained by CO2 forced into the stomach during mask ventilation, antacids in the stomach, or carbonated drinks in the stomach. False-negative results may be seen with very low tidal volumes and low end-tidal CO2 concentrations during severe hypotension or cardiac arrest. During cardiopulmonary resuscitation (CPR), a negative result requires an alternative method of confirming the position of the endotracheal tube because compromised circulation causes low end-tidal CO2.12 Other methods used to confirm endotracheal intubation include fiberoptic endoscopy with direct visualization of the tracheal rings and carina, pulse oximetry (low saturation is a late sign for esophageal intubation), blood gas analysis, chest radiography, and a variety of detection devices. Please refer to Chapter 12 for more information regarding the confirmation of endotracheal intubation.

The aftercare is the same as for any intubated patient. Secure the endotracheal tube with tape or a commercially available device. Administer adequate sedation and neuromuscular relaxation as necessary. Place a nasogastric tube to decompress the stomach.

The complications associated with RSI are numerous (Table 10-7), ranging from minor airway trauma to cerebral anoxia and death. These can result from the RSI or the intubation. The technique of RSI should be performed only by experienced physicians. The availability of alternate invasive airway devices and techniques can often prevent complications if oral endotracheal intubation is unsuccessful. A more complete discussion is contained in Chapter 11.

RSI is the preferred method to secure an airway on an emergent basis and where there is a risk of aspiration of gastric contents. In experienced hands, it is a relatively safe procedure with few complications. The choice of pharmacologic agents used will vary by physician experience, physician preference, the clinical condition of the patient, and the pharmacology of the agents.