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Indications:
1. Trauma patients with Glasgow Coma Scale of nine or less with gag reflex. 2. Trauma patients with significant facial trauma and poor airway control. 3. Closed head injury or major stroke with unconsciousness. 4. Burn patients with airway involvement and inevitable airway loss. 5. Respiratory exhaustion such as severe asthma, CHF or COPD with hypoxia. 6. Overdoses with altered mental status where loss of airway is inevitable. |
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Preparation: Procedure: |
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Rapid Sequence Intubation Indications * Failure to maintain airway tone o Swelling of upper airway as in anaphylaxis or infection o Facial or neck trauma with oropharyngeal bleeding or hematoma * Decreased consciousness and loss of airway reflexes o Failure to protect airway against aspiration - Decreased consciousness that leads to regurgitation of vomit, secretions, or blood * Failure to ventilate o End result of failure to maintain and protect airway o Prolonged respiratory effort that results in fatigue or failure, as in status asthmaticus or severe COPD * Failure to oxygenate (ie, transport oxygen to pulmonary capillary blood) o End result of failure to maintain and protect airway or failure to ventilate o Diffuse pulmonary edema o Acute respiratory distress syndrome o Large pneumonia or air-space disease o Pulmonary embolism o Cyanide toxicity, carbon monoxide toxicity, methemoglobinemia * Anticipated clinical course or deterioration (eg, need for situation control, tests, procedures) o Uncooperative trauma patient with life-threatening injuries who needs procedures (eg, chest tube) or immediate CT scanning o Stab wound to neck with expanding hematoma o Septic shock with high minute-ventilation and poor peripheral perfusion o Intracranial hemorrhage with altered mental status and need for close blood pressure control o Cervical spine fracture with concern for edema and loss of airway patency * Absolute o Total upper airway obstruction, which requires a surgical airway o Total loss of facial/oropharyngeal landmarks, which requires a surgical airway * Relative o Anticipated "difficult" airway, in which endotracheal intubation may be unsuccessful, resulting in reliance on successful bag-valve-mask (BVM) ventilation to keep an unconscious patient alive + In this scenario, techniques for awake intubation and difficult airway adjuncts can be used. + Multiple methods can be used to evaluate the airway and the risk of difficult intubation (eg, LEMON rule, 3-3-2, Mallampati class, McCormack and Lehane grade). Please refer to the Difficult Airway Assessment section below for details. o The "crash" airway, in which the patient is in an arrest situation, unconscious and apneic + In this scenario, the patient is already unconscious and may be flaccid; further, no time is available for preoxygenation, pretreatment, or induction and paralysis. + BVM ventilation, intubation, or both should be performed immediately without medications. Anesthesia Rapid sequence intubation (RSI) is predicated on the administration of medications in a specific sequence. The 3 phases of medication administration are pretreatment, induction, and paralysis. Preoxygenation is helpful before these phases begin. Preoxygenation * Preoxygenation with high-flow oxygen via a nonrebreather mask for 5 minutes leading up to intubation results in supersaturation of oxygen in the alveoli by way of displacement of nitrogen (nitrogen washout). This allows the patient to maintain blood oxygen saturation during the apneic period of paralysis and allows the practitioner more time to successfully intubate. * In healthy adult volunteers who have been preoxygenated for 3-5 minutes, the average time to desaturation (oxygen saturation < 90%) is approximately 8 minutes. This time is significantly shorter in patients who are critically ill and have a much higher metabolic demand for oxygen.[1] * Use the least assistance necessary to obtain good oxygen saturation and adequate preoxygenation (see Technique section below). o High-flow oxygen via nonrebreather mask may be appropriate for a patient with good respiratory effort. o High-flow oxygen via well-fitting bag-valve-mask (BVM) without additional positive pressure (ie, squeezing the bag) may be needed for those with more respiratory compromise. o High-flow oxygen via BVM with positive pressure assistance (squeezing the bag) is used only when necessary. Pretreatment * Pretreatment agents may be used to mitigate the physiologic response to laryngoscopy and induction and paralysis, which may be undesirable in certain clinical situations. * Pretreatment medications are typically administered 2-3 minutes prior to induction and paralysis. These medications can be remembered by using the mnemonic LOAD (ie, Lidocaine, Opioid analgesic, Atropine, Defasciculating agents). o Lidocaine (1.5 mg/kg IV) may suppress the cough or gag reflex experienced during laryngoscopy and has been considered to play a role in blunting increases in mean arterial pressure (MAP), heart rate (HR), and intracranial pressure (ICP). For this reason, it is commonly administered to patients with suspected intracranial hemorrhage, tumor, or any other process that may result in increased ICP, and it may be considered as part of RSI for patients in whom increased MAP could be harmful (eg, leaking aortic aneurysm). However, studies do not consistently demonstrate the effectiveness of lidocaine for these indications in patients in the emergency department (ED), and, based on this lack of evidence, a statement regarding its absolute indication cannot be made.[8, 9, 10, 11, 12, 13, 14, 15, 16, 7] o Opioid analgesic (fentanyl 3 mcg/kg IV) mitigates the physiologic increase in sympathetic tone associated with direct laryngoscopy (ie, blunts increases in blood pressure, heart rate, and mean arterial pressure). One author recommends this in patients with suspected high ICP,[17, 18, 19] though some data also suggest that these agents may increase ICP.[20, 21, 22, 23, 24, 25] Opioid analgesics may also be useful in patients with an aortic emergency (eg, aortic dissection or leaking aortic aneurysm) in whom blood pressure spikes should be avoided. At this time, no conclusive evidence supports the use of opioids in RSI. o Atropine (0.02 mg/kg IV) may decrease the incidence of bradydysrhythmia associated with direct laryngoscopy (stimulation of parasympathetic receptors in the laryngopharynx) and administration of succinylcholine (direct stimulation of cardiac muscarinic receptors). Previous recommendations indicated that all children younger than 10 years receive atropine prior to intubation, but this has fallen out of favor because of the lack of supporting data. Even if bradydysrhythmias occur, they are usually self-limited and clinically nonrelevant. However, atropine should be available in case a clinically significant decrease in heart rate occurs. Because of the increase in cardiac vagal tone, atropine can be considered for use in children younger than 1 year and should at least be at the bedside in this age group.[26, 27] o Some evidence indicates that bradycardia can occur equally with or without atropine during intubation.[28, 26] Atropine can also be used in adolescents and adults for symptomatic bradycardia. o A "defasciculating" dose of a nondepolarizing agent may reduce the duration and intensity of muscle fasciculations observed with the administration of succinylcholine (due to the stimulation of nicotinic acetylcholine receptors). The recommended dose is 10% of the paralyzing dose (eg, 0.01 mg/kg for vecuronium). Equivocal studies suggest such pretreatment may help reduce increases in intracranial pressure related to the procedure. o The crux of RSI is to take the awake patient, with an assumed full stomach, and very quickly induce a state of unconsciousness and paralysis and securing the airway. This is done without positive pressure ventilation, if possible. Induction * Induction agents provide a rapid loss of consciousness that facilitates ease of intubation and avoids psychic harm to the patient. o Etomidate (Amidate) (0.3 mg/kg IV) - Rapid onset, short duration, cerebroprotective, and not associated with significant drop in blood pressure; hemodynamically neutral compared with other agents, such as sodium thiopental. Most common agent used in the United States. o Ketamine (Ketalar) (1-2 mg/kg IV) - "Dissociative" state, analgesic properties, bronchodilator, may increase intracranial pressure. Consider for patients with asthma or anaphylactic shock; avoid in patients with suspected or known aortic dissection or abdominal aortic aneurysm and in patients with acute myocardial infarction. The general teaching has also been to avoid use of ketamine in patients in whom increased ICP is a concern; in particular, trauma patients with evidence of head injury. However, a review of recent literature supports its use in this scenario as the hemodynamic stimulation induced by ketamine may, in fact, improve cerebral perfusion and prevent secondary penumbra ischemia. Furthermore, in the laboratory, ketamine seems to have neuroprotective properties.[29, 30, 31] o Propofol (Diprivan) (2 mg/kg IV) - Rapid onset, short duration, cerebral protective. However, propofol is a myocardial depressant and also decreases systemic vascular resistance. o Midazolam (Versed) (0.3 mg/kg IV) - Slower onset (2-3 min without opioid pretreatment) and longer duration (up to several hours) than etomidate. A study by Sagarin et al from a national airway registry demonstrated that midazolam is usually underdosed when used for RSI, presumably because of the concern for hypotension.[3] Note that the induction dose is about 20 mg for a 70-kg person. Use of midazolam as an induction agent is not recommended because of its delayed time to induction, predilection for hypotension at induction doses, and prolonged duration of action. Paralysis * Paralyzing agents provide neuromuscular blockade and are administered immediately after the induction agent. * Neuromuscular blockade does not provide sedation, analgesia, or amnesia; thus, administering a potent induction agent is important. o Depolarizing neuromuscular blocker (eg, succinylcholine [Anectine] at 2 mg/kg IV or 4 mg/kg IM): Rapid onset (45-60 sec) and shortest duration of action (8-10 min). Should be used with caution in patients with known or suspected hyperkalemia and those with neuromuscular disease. o Zink's 1995 prospective study of 100 patients in the ED undergoing RSI did not find a change in serum potassium level from before to after RSI with succinylcholine. Exclusion criteria were minimal; a limitation was that postintubation potassium level was checked at only 1 time interval (5 min).[32] o Nondepolarizing neuromuscular blocker (eg, rocuronium [Zemuron] at 1-1.2 mg/kg IV): Slightly longer onset of action (60-75 sec) than succinylcholine and longer duration of action (30-60 min). Use with caution in patients in whom difficult intubation is possible. Does not result in muscle depolarization or defasciculation and does not exacerbate hyperkalemia. Equipment * Laryngoscope (see image below) o Confirm that light source is functional prior to intubation. o A 2010 study demonstrated that single-use metal laryngoscope blades resulted in a lower failed intubation rate than did reusable metal blades.[33] * 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 * Assistant for cricoid pressure Positioning In cases of trauma in which cervical spine injury is suspected and not yet ruled out, intubation must be performed without movement of the head. Immobilization is best provided by an experienced assistant. In cases in which cervical injury is not a concern, proper head positioning greatly improves visualization. * In the neutral position, the oral, pharyngeal, and laryngeal axes are not aligned to permit adequate visualization of the glottic opening (see image below). * Place the patient in the sniffing position for adequate visualization; flex the neck and extend the head. This position helps to align the axes and facilitates visualization of the glottic opening. * Recent studies have shown that simple head extension alone (without neck flexion) was as effective as the sniffing position in facilitating endotracheal intubation.[34] Technique Preparation * Confirm that intubation equipment is functional. * Assess the patient for difficult airway (see Difficult Airway Assessment section below for recommended method). If the patient meets criteria for difficult airway, rapid sequence intubation (RSI) may be inappropriate. Nonparalysis procedures may be an alternative. * Establish intravenous access. * Draw up essential drugs and determine sequence of administration (induction agent immediately followed by paralytic agent). * Review possible contraindications to medications. * Attach necessary monitoring equipment. * Check endotracheal (ET) tube cuff for leak. * Ensure functioning light bulb on laryngoscope blade. Preoxygenation * Administer 100% oxygen via a nonrebreather mask for 3 minutes for nitrogen washout. This is done without positive pressure ventilation using a tight seal. * Though rarely possible in the emergent situation, the patient can take 8 vital capacity (as deep as possible) breaths of 100% oxygen. Studies have shown this can prevent apnea-induced desaturation for 3-5 minutes.[35] * Assist ventilation with bag-valve-mask (BVM) system only if needed to obtain oxygen saturation ≥ 90%. Pretreatment * Consider administration of drugs to mitigate the adverse effects associated with intubation. * See Anesthesia for more information. 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 * Though clinical dogma dictates that the Sellick maneuver (firm pressure over the cricoid cartilage to compress the proximal esophagus) be initiated to prevent regurgitation of gastric contents, literature is lacking in support of this technique and in fact may impede laryngeal view. o Initiate this maneuver upon observing the beginning of unconsciousness. o Maintain pressure throughout intubation sequence until the position of the ET tube is verified. Note that proper laryngeal view has been shown to be best accomplished by the bimanual method and should be used if the Sellick maneuver fails to show the vocal cords. o Classical teaching dictates that cricoid pressure decreases the risk of gastric regurgitation into the lungs. However, in a study by Smith et al, the esophagus was partially lateral to the trachea in more than 50% of the subjects.[36] Also, in an ultrasound study, 29 of 33 esophagi were partially displaced to the left of the trachea.[37] In a meta-analysis, Butler and Sen showed that little evidence supports the notion that cricoid pressure decreases the risk of aspiration in RSI.[38] Placement with proof * Visualize the ET tube passing through the vocal cords. * Confirm tube placement. o Observe color change on a qualitative end-tidal carbon dioxide device. o 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. o Two pilot studies have shown that ultrasonography can reliably detect passage of a tracheal tube into either the trachea or esophagus without inadvertent ventilation of the stomach.[37, 39] Postintubation management * Secure the ET tube into place. * Initiate mechanical ventilation. * Obtain a chest radiograph. o Assess pulmonary status. o Note this modality does not confirm placement; rather, it assesses the height above the carina. o Ensure that mainstem intubation has not occurred. * Administer appropriate analgesic and sedative agents for patient comfort, to decrease O2 demand, and to decrease ICP. Pearls # To simplify rapid sequence intubation (RSI), one can think of administering essentially 2 drugs: an induction agent (etomidate) and a paralytic agent (succinylcholine). These fulfill the criteria of possessing a short onset/duration and high potency. # To intubate a trauma patient with C-spine precautions, the cervical collar may be removed with a dedicated assistant providing inline immobilization. Removing the anterior part of the cervical collar while maintaining inline cervical spine immobilization is acceptable and may cause less cervical spine movement than cervical collar immobilization during laryngoscopy for endotracheal intubation. # Position the head and neck in 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. # The patient must be adequately preoxygenated to prevent desaturation during the period of apnea after the paralytic agent has been administered (to minimize the risk of gastric content aspiration). 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 nonrebreather mask is usually used, but for patients who are noted to desaturate (eg, beyond 90%), breaths delivered via 100% oxygen bag-valve-mask (BVM) 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 the patient is not able to maintain airway reflexes) and should be continued until inflation of the tracheal cuff of the endotracheal tube in the trachea. Note, however, that recent evidence questions the benefit of this modality.[38, 40] # Firm backward, upward, and rightward pressure (BURP) on the patient's thyroid cartilage can improve the Cormack/Lehane view up to one full grade. Typically, the assistant performing the Sellick maneuver can assist, resulting in a combined Sellick-BURP maneuver. # A No. 3 Macintosh or No. 3 Miller blade is generally sufficient for most patients, but a No. 4 blade (ie, next larger size) may be required in some adults. Note, some clinicians routinely use a No. 4 Macintosh blade, as it can be used in substitution of a Miller without switching blades. # A recent study by Brown III et al shows an overall improvement in glottic exposure with video compared to direct laryngoscopy.[41] More importantly, 25% of patients undergoing direct laryngoscopy displayed a poor glottic view; the use of video laryngoscopy improved this to a good view in nearly 80% of these patients. # 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 for patients with a critical disease or traumatic process. The selection of technique and specific agents is determined individually 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. # Accurate confirmation of correct placement of the tube in the trachea is essential. * Direct visualization of the tube was previously the criterion standard for confirming placement; however, this method can be fraught with human error. * The current criterion standard is end-tidal carbon dioxide detection, using either a calorimetric capnometer that changes color from purple to yellow with CO2 exposure or a quantitative capnometer that measures CO2 levels and can display a waveform. The yellow color change should occur rapidly within 1-2 breaths, and esophageal or supraglottic placement should be assumed if the color change is less rapid or does not occur at all. Color change may not be reliable in cases of prolonged cardiac arrest. * Clinical parameters such as pulse oximetry readings or tube condensation may be nonspecific and misleading. A canine study by Kelly and colleagues demonstrated tube condensation in up to 83% of esophageal intubations.[42] # The step of preoxygenation maximizes hemoglobin and plasma oxygen saturation and creates an oxygen reservoir in the lungs by replacing nitrogen at the alveolar level and supersaturating the blood with oxygen (nitrogen washout). * This oxygen reservoir in the lungs can eliminate the need for BVM ventilation for most patients undergoing RSI during the iatrogenically created period of apnea. * Preoxygenation is accomplished by delivering 100% oxygen at high flow given to a spontaneously breathing patient through a nonrebreather mask for 3 minutes without "bagging" the patient. # Studies such as the one by Barker and colleagues have shown that 8 vital capacity breaths over 60 seconds results in the same degree of preoxygenation as the standard 3 minutes of tidal volume breathing of 100% oxygen by mask. This technique may be used as an alternate to the traditional 3-min tidal volume technique. Comorbidities such as the presence of a hypermetabolic state, obesity, or a primary respiratory problem (eg, congestive heart failure, acute respiratory distress syndrome, pneumonia) cause patients to desaturate rapidly despite attempts at adequate preoxygenation. # A patient who is hypoxemic during attempts at intubation should undergo positive pressure ventilation with a BVM to raise PaO2 levels. Consider applying cricoid pressure Complications * Esophageal intubation * Iatrogenic induction of an obstructive airway * Right mainstem intubation * Pneumothorax * Dental trauma * Postintubation pneumonia * Vocal cord avulsion * Failure to intubate * Hypotension * Aspiration Difficult Airway Assessment Several methods exist to quickly assess the probability of success during tracheal intubation.[1] One tool for rapid assessment is the LEMON law, as described below. A patient in extremis may not be able to cooperate with all the sections of the LEMON assessment. 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 in the first image below), and is able to fit 2 finger breadths between the hyoid bone and the thyroid cartilage (see thyrohyoid distance in the second image below). 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 (see image below). 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. |