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Clinical Procedures > Respiratory Management
Tracheal Intubation, Rapid Sequence Intubation
Article Last Updated: Mar 13, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 15  
Author: Rick Kulkarni, MD, Medical Director, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Editors: Andrew K Chang, MD, Assistant Professor, Department of Emergency Medicine, Albert Einstein College of Medicine, Montefiore Medical Center; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Luis M Lovato, MD, Assistant Clinical Professor, David Geffen School of Medicine at UCLA; Director of Critical Care, Department of Emergency Medicine, Olive View/UCLA Medical Center; Gil Z Shlamovitz, MD, Staff Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center; Jonathan Adler, MD, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital; Division of Emergency Medicine, Harvard Medical School
Author and Editor Disclosure
Synonyms and related keywords:
endotracheal intubation, oral intubation, tracheal intubation, orotracheal intubation, intubation, rapid sequence intubation, RSI, anesthesia and intubation, airway pharmacology, managing the acute airway, emergency airway management, emergency intubation, rapid tracheal intubation, difficult airway
Tracheal intubation is a complex skill that takes experience and confidence to successfully perform. It can be performed in any clinical setting in which the appropriate equipment, including a ventilator, medications, and trained personnel, is available. The procedure should be performed in any of several common patient presentations, including, but not limited to, cardiac arrest, sepsis, airway obstruction, multiple trauma, closed head injury when the patient is having difficulty maintaining a patent airway, problems with ventilation or oxygenation, or an anticipated deterioration of the patient's condition. Except for defibrillation in witnessed pulseless loss of consciousness, tracheal intubation is the first procedure performed on a critically ill patient with respiratory insufficiency or respiratory failure.
In the emergency department setting, patients are typically tracheally intubated using a specific protocol known as rapid sequence intubation (RSI). Unlike in the preoperative setting, in which the patient has fasted for a minimum of 6-8 hours before the procedure, patients who need emergent intubation are assumed to have a full stomach. The key point in RSI is to not assist ventilation (eg, bag-valve-mask ventilation) of the patient for continued oxygenation after the administration of paralytic medications to avoid insufflation of the stomach, leading to regurgitation of stomach contents and possible aspiration.
With adequate preoxygenation preceding paralysis, desaturation is avoided during RSI despite a period of apnea. In healthy adult volunteers who have been preoxygenated for 3-5 minutes, the average time to desaturation (defined as an oxygen saturation <90%) is approximately 8 minutes. A patient in critical condition with respiratory compromise may have significantly less "reserve."
- Failure to protect the airway
- Failure to maintain the airway
- Failure of ventilation
- Failure of oxygenation
- Anticipated clinical deterioration (eg, expanding neck hematoma)
- Absolute
- Total upper airway obstruction
- Total loss of facial landmarks
- Relative
- Anticipated difficult airway
RSI is a protocol predicated on the successful administration of several medications in a specific sequence. The medications fall into one of several categories of agents: pretreatment, induction, and paralytic. - Pretreatment agents help to mitigate the adverse effects associated not only with the physical process of intubation (eg, undesirable patient behavior such as coughing or gagging and typically observed physiologic changes) but also with other medications that are used in the procedure, such as succinylcholine. In addition to oxygen, these medications can be remembered by using the mnemonic LOAD.
- Oxygen administration per protocol creates a surplus of dissolved oxygen in the blood, thereby increasing the time to desaturating during the procedure.
- Lidocaine (1.5 mg/kg) suppresses the cough reflex, may decrease cerebral oxygen demand, and may relieve bronchospasm associated with intubation. It should be used in patients with a "tight brain or tight lungs" (eg, suspected or known increased intracranial pressure, reactive airways disease).
- Opioid analgesic (eg, fentanyl at 3 mcg/kg) mitigates the typical increase in sympathetic tone usually noted with direct laryngoscopy (ie, controls increases in blood pressure, heart rate, and mean arterial pressure). It may also provide systemic analgesia and light sedation.
- Atropine (0.02 mg/kg) may decrease the incidence of dangerous bradydysrhythmia associated with direct laryngoscopy (stimulation of parasympathetic receptors in the laryngopharynx) and administration of succinylcholine (direct stimulation of cardiac muscarinic receptors). When used, it is usually administered to children younger than 10 years; however, it also can be used in adolescents and adults if necessary (eg, symptomatic bradycardia).
- Defasciculating agents (10% of the full paralyzing dose of a nondepolarizing neuromuscular blocking agent) reduce the duration and intensity of muscle fasciculations observed with the administration of succinylcholine (due to the stimulation of nicotinic acetylcholine receptors). Equivocal studies suggest such pretreatment may help to reduce increases in intracranial pressure related to the procedure.
- Induction agents provide rapid loss of consciousness immediately prior to paralysis and intubation.
- Sodium thiopental (Pentothal) (3-5 mg/kg) - Rapid onset, short duration, cerebroprotective, associated with significant drop in blood pressure. Generally avoided in most patients since status of cardiovascular reserve is not known in the emergent setting and superior agents are available.
- Etomidate (Amidate) (0.3 mg/kg) - Rapid onset, short duration, cerebroprotective, and not associated with significant drop in blood pressure; hemodynamically neutral compared with other agents, such as sodium thiopental. Used in most intubations in the United States.
- Ketamine (Ketalar) (1-2 mg/kg) - "Dissociative" state, analgesic properties, bronchodilator, may increase intracranial pressure. Consider for patients with asthma or anaphylactic shock; avoid in other patients such as trauma patients at risk for head injury, patients with suspected or known aortic dissection or abdominal aortic aneurysm, and patients with acute myocardial infarction.
- Midazolam (Versed) (0.2-0.3 mg/kg) - Slower onset and longer duration than etomidate or thiopental. May be used as a second-line agent.
- Paralyzing agent must be administered immediately following the administration of the induction agent. Neuromuscular blockade does not provide sedation, analgesia, or amnesia.
- Depolarizing neuromuscular blocker (eg, succinylcholine [Anectine] at 2 mg/kg IV or 4 mg/kg IM)
- Non-depolarizing neuromuscular blocker (eg, vecuronium [Norcuron] at 0.15 mg/kg IV, rocuronium [Zemuron] at 0.6-1 mg/kg IV)
- Laryngoscope (confirm that light source is functional prior to intubation)
Laryngoscope handle, #3 Macintosh (curved) blade, and #3 Miller (straight) blade.
- Endotracheal (ET) tube
- Stylet
- Syringe, 10 mL (to inflate ET tube balloon)
- Suction catheter (eg, Yankauer)
- Carbon dioxide detector (eg, Easycap)
- Oral and nasal airways
- Ambu bag and mask attached to oxygen source
Head positioning for tracheal intubation is essential.
- Preparation
- Confirm that intubation equipment is functional.
- Assess the patient for difficult airway (see Difficult Airway Assessment for recommended method). If the patient meets criteria for difficult airway, rapid sequence intubation may be inappropriate. Awake laryngoscopy may be an alternative.
- Establish intravenous access.
- Draw up essential drugs and determine sequence of administration.
- Review possible contraindications to medications.
- Attach necessary monitoring equipment.
- Check endotracheal (ET) tube cuff for leak.
- Tighten light bulb on laryngoscope blade.
- Preoxygenation
- If time allows, administer 100% oxygen via a non-rebreather mask for 3 minutes.
- If time is limited, instruct patient to take 8 vital capacity (as deep as possible) breaths of 100% oxygen.
- Assist ventilation with bag-valve-mask system, if needed, to obtain oxygen saturation ³90%.
- Pretreatment: Administer drugs to mitigate the adverse effects associated with intubation.
- Paralysis with induction
- Administer a rapidly-acting induction agent to produce loss of consciousness.
- Administer a neuromuscular blocking agent immediately after the induction agent.
- These medications should be administered as an intravenous push.
- Protection and positioning
- Apply Sellick's maneuver (firm pressure over the cricoid cartilage) to prevent regurgitation of gastric contents.
- Initiate this maneuver upon observing the beginning of unconsciousness.
- Maintain pressure throughout intubation sequence until the position of the ET tube is verified.
- Placement with proof
- Intubate the patient.
- Confirm tube placement.
- Observe color change on a qualitative end-tidal carbon dioxide device.
- Use the 5-point auscultation method: listen over each lateral lung field, the left axilla, and the left supraclavicular region for good breath sounds. No air movement should occur over the stomach.
- Post-intubation management
- Tie the ET tube into place.
- Initiate mechanical ventilation.
- Obtain a chest radiograph.
- Assess pulmonary status.
- Confirm tube placement (do not use radiograph as primary method to confirm tube placement).
- Ensure that mainstem intubation has not occurred.
- Administer appropriate analgesic and sedative agents for patient comfort.
- To intubate a trauma patient with C-spine precautions, the cervical collar may be removed with a dedicated assistant providing in-line immobilization.
- Position the head and neck into the sniffing position by flexing the neck and extending the atlanto-occipital joint. Reposition the head if an adequate view of the glottic opening is not achieved.
- In order to prevent desaturation during the period of apnea after the paralytic agent has been administered (to minimize the risk of gastric content aspiration), the patient must have been adequately preoxygenated. The least amount of ventilation support required to obtain good oxygen saturation should be used during this period. Blow-by high-flow oxygen via a non-rebreather mask is usually used, but for patients who are noted to desaturate (eg, beyond 90%), breaths delivered via 100% oxygen bag-valve-mask, perhaps even with 2 operators, may be required.
- To minimize the risk of gastric aspiration, the Sellick maneuver (firm pressure over the thyroid cartilage) may be initiated as soon as positive pressure ventilation is started (eg, during pretreatment if tolerated by the patient) and should be continued until inflation of the tracheal cuff of the endotracheal tube in the trachea.
- Firm backward, upward, and rightward (BURP) pressure on the patient's thyroid cartilage can improve the Cormack and Lehane view up to one full grade. Typically, the assistant performing the Sellick maneuver can assist, resulting in a combined Sellick-BURP maneuver.
- A #3 Macintosh or Miller blade is generally sufficient for most patients, but a #4 blade (ie, next larger size) may be required in some adults.
- Provide appropriate analgesia and sedation for patient comfort after RSI is successfully completed, especially if the patient is chemically paralyzed with a longer-acting paralytic agent (eg, vecuronium).
- RSI is a procedure performed for patients with a critical disease or traumatic process. The selection of technique and specific agents is individually determined for each patient and situation. This article focuses on straightforward RSI for adults. Different techniques, equipment, and agents may be used for complex or rescue situations.
- Right mainstem intubation
- Pneumothorax
- Dental trauma
- Post-intubation pneumonia
- Vocal cord avulsion
- Failure to intubate
- Hypotension
- Esophageal intubation
DIFFICULT AIRWAY ASSESSMENT
Several methods exist to quickly assess the probability of success during tracheal intubation. One tool for rapid assessment is the LEMON law, as described below.
L: Look externally
Assessing the difficulty of an airway based on external physical features is not sensitive (not all patients who have a difficult airway appear to have a difficult airway prior to intubation) but is quite specific (most patients who appear to have a difficult airway do indeed have a difficult airway). Physical features such as a small mandible, large tongue, and short bull neck are all red flags for a difficult airway.
E: Evaluate the 3-3-2 rule
The chance for success is increased if the patient is able to insert 3 of his or her own fingers between the teeth, can accommodate 3 finger breadths between the hyoid bone and the mentum (see hyomental distance below), and is able to fit 2 finger breadths between the hyoid bone and the thyroid cartilage (see thyrohyoid distance below).
Hyomental distance (3 finger breadths).
Thyrohyoid distance (2 finger breadths).
M: Mallampati classification
The Mallampati assessment is ideally performed when the patient is seated with the mouth open and the tongue protruding without phonating. In many patients intubated for emergent indications, this type of assessment is not possible. A crude assessment can be performed with the patient in the supine position to gain an appreciation of the size of the mouth opening and the likelihood that the tongue and oropharynx may be factors in successful intubation.
Mallampati classification.
O: Obstruction
Obstruction of the upper airway is a marker for a difficult airway. Three signs of upper airway obstruction are difficulty swallowing secretions (secondary to pain or obstruction), stridor (an ominous sign which occurs when <10% of normal caliber of airway circumference is clear), and a muffled (hot-potato) voice.
N: Neck mobility
The inability to move the neck affects optimal visualization of the glottis during direct laryngoscopy. Cervical spine immobilization in trauma (with a C-collar) can compromise normal mobility, as can intrinsic cervical spine immobility due to medical conditions such as ankylosing spondylitis or rheumatoid arthritis.
American Academy of Emergency Medicine
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American Association for Respiratory Care
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eMedicine.com, Inc: Prehospital Airway Devices
eMedicine.com, Inc: Rapid Sequence Induction
eMedicine.com, Inc: Rapid Sequence Induction – Induction and Pretreatment Medications
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Proper alignment of the axes for tracheal intubation. |
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Laryngoscope handle, #3 Macintosh (curved) blade, and #3 Miller (straight) blade. |
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- Bair AE, Filbin MR, Kulkarni RG, Walls RM. The failed intubation attempt in the emergency department: analysis of prevalence, rescue techniques, and personnel. Journal of Emergency Medicine. 2002;23(2):131-40. [Medline].
- Sagarin MJ, Barton ED, Chng YM, Walls RM. Airway management by US and Canadian emergency medicine residents: a multicenter analysis of more than 6,000 endotracheal intubation attempts. Annals of Emergency Medicine. 2005;46(4):328-36. [Medline].
- Walls RM. Rapid Sequence Intubation. In: Walls RM, ed-in-chief; Murphy MF, Luten RC, Schneider RE, eds. Manual of Emergency Airway Management. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2004:22-31.
- Walls RM. The Decision to Intubate. In: Walls RM, ed-in-chief; Murphy MF, Luten RC, Schneider RE, eds. Manual of Emergency Airway Management. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2004:1-7.
Tracheal Intubation, Rapid Sequence Intubation excerpt Article Last Updated: Mar 13, 2006
Topic originally published: Mar 8, 2006
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