Endotracheal intubation in airway management is the placement of an endotracheal tube (ETT) in a patient’s trachea to maintain an open airway.
Indications for Intubation
Distress may include atypical vital signs, respiratory distress, low blood pressure, low heart rate, and low O2 saturation, as well as other atypical findings in the patient. Intubation can help provide oxygenation and alleviate the neonate from the work of breathing. Less stress will be placed on the patient and allow for improved management of cardiorespiratory symptoms.
Meconium is one of the first stools produced by a newborn infant after birth. It is made up of ingested intestinal epithelial cells, bile acids, digestive enzymes, lanugo hair, and amniotic fluid. Respiratory problems can occur as a result of meconium aspiration syndrome (MAS) when infants pass stool into the amniotic fluid prior to birth. Current protocol recommends intubation for MAS when the newborn infant presents as nonvigorous, defined as either poor muscle tone, HR < 100 beats/min, or a poor respiratory effort.
Prematurity With Respiratory Distress
Respiratory distress in infants may be caused by an insufficiency in the production of surfactant. When noninvasive measures prove ineffective, a physician can utilize tracheal intubation to provide adequate ventilation.
See Cause of Respiratory Distress discussed previously, and Chapter 12.
Airway obstruction that is caused by a foreign body, or swelling, or by an injury to the trachea, larynx, or bronchi may be treated by tracheal intubation. Bypassing the blockage with an ETT allows the patient to maintain an open airway and preserve normal respiration.
Transport to a Higher Level of Care
Controversy exists on the necessity of intubation prior to transfer to higher level of care in patients in whom there is a danger of airway decompensation. Community physicians may not express the same level of comfort and self-confidence in performing advanced procedures in pediatric patients as their receiving hospital counterparts. If a child is in danger of losing his or her airway, the transferring physician must weigh the benefits and risks of deferring intubation. A child who decompensates during transport may have a worse outcome if intubation is required in an out-of-hospital setting. However, specially trained critical care transport providers demonstrate a high rate of successful intubation.
Visual grading scales have been utilized to aid the physician in assessment of a patient’s predicted difficulty with endotracheal intubation. Studies have questioned the specificity of such grading systems. The classifications may not be as applicable to small children due to patient’s cooperation with examination and anatomical variation.
The Mallampati score is a grading scale that applies a 1-4 numerical annotation: 1 is a patient who is relatively easy to intubate, and 4 is a patient who is very difficult to intubate. Numerical values are assigned by assessing a patient’s oral cavity preprocedure (Figure 9–5).
Class 1: visualize faucial pillars, soft palate, and uvula
Class 2: visualize faucial pillars and soft palate
Class 3: visualize hard and soft palates
Class 4: visualize hard palate only
The Cormack-Lehane system categorizes the difficulty of intubation by the visibility of specific anatomical features upon laryngoscopy (Figure 9–6).
Grade 1: view the entire laryngeal aperture
Grade 2: view parts of the laryngeal aperture or the arytenoids
Grade 3: view only the epiglottis
Grade 4: view of only the soft palate
An argument has been made for the use of an uncuffed endotracheal tube (ETT) for intubation of children younger than 8 years. However, the advantages of a cuffed ETT include a possibly better seal, lower gas leak, and a decreased chance of recurrent laryngoscopy. The recommended cuff inflation pressure is less than 20 cm H2O.
The traditional teaching of using a patient’s fifth finger to gauge the size of the ETT may result in tube sizes that are 1-2 mm larger than necessary. Age formulas given below are preferred over finger estimations, however the latter is clinically acceptable when no other means are available.
The Broselow tape is a color-coded system used by health care professionals to determine appropriate medication doses and equipment sizes based on a pediatric patient’s height and weight. The Broselow tape is a means to determine the correct ETT size for a pediatric patient in the absence of age-related information in emergent situations.
A bag-valve-mask is a noninvasive means of providing oxygen to a patient during preparation for intubation, as discussed previously in the Bag-valve-mask section.
Suction is used during intubation to remove apparent secretions that can potentially hinder the procedure.
Laryngoscope Blade: Miller vs MacIntosh
A laryngoscope blade is used during endotracheal intubation to allow the physician to view the larynx directly. The blades come in variable sizes and shapes with the most common the Miller (straight) and the Macintosh (curved). The difference in intubation success with the blades can be attributed to the proper technique relative to the blade used, as well as the choice of correct size.
The Miller blade is placed posterior to the epiglottis and directly lifts the epiglottis. This is the preferred blade for infants and young children, who may have a “floppy” epiglottis. The Miller blade is generally used for children years and older, but if necessary the Miller blade can be used for children of any age. A Miller 0 blade should be used only in premature infants and average-sized newborns. A Miller 1 blade is appropriate for most infants beyond the immediate newborn period.
The Macintosh blade slips in the vallecula (space between the epiglottis and the tongue) and indirectly lifts the epiglottis. The Macintosh curved blade is used primarily in older children and adults.
The size of the laryngoscope blade is estimated using the distance between the upper incisor teeth and the angle of the mandible. In children younger than 8 years, studies have shown that blades that measured within 1 cm of this anatomical distance had better first attempt results.
A stylet is a device used to assist and guide in the placement of an ETT during the intubation of patient. The stylet is placed in the ETT tube and removed only after the tube has been placed successfully for intubation. It is essential to leave enough distance between the end of the stylet and the end of the ETT to avoid injury to the airway.
Preoxygenation with a 100% oxygen source in a spontaneously breathing patient allows for “nitrogen washout” and provides an oxygen reservoir for patients while they are apneic during an intubation procedure. Studies have shown that preoxygenation greater than the customary 3-4 minutes has little to no benefit.
Current recommendations indicate the use of a non-rebreather facemask to provide preoxygenation. Noninvasive ventilation by means of CPAP may be a more effective means of preoxygenation in critically ill patients.
The “sniffing” position is recommended for a patient in preparation for intubation. The position provides adequate visualization of the glottis opening. It is achieved by moving the head forward and slightly extending the atlanto-occipital joint (Figure 9–7).
Rapid sequence induction (RSI) is the preferred method of intubation in patients with no known increased risk of complication. The RSI consists of prompt administration of an induction agent and neuromuscular blocking agent. The combination of the two drugs causes immediate paralysis and sedation in a patient and results in ideal tracheal intubation conditions (Table 9–1). Studies have shown efficacy and safety of RSI in pediatric patients.
Table 9–1.Drug dosages. |Favorite Table|Download (.pdf) Table 9–1. Drug dosages.
| ||Dosage ||Comments ||Onset ||Duration |
|Pretreatment || || || || |
|Atropine ||.02 mg/kg IV ||minimum dose: 0.1 mg ||2-4 min ||4 h |
| ||IV/IO: .04-.06 mg ||Maximum dose: Child: 0.5 mg || |
| || ||Maximum dose: Adult: 1 mg || |
|Neuroprotective || || || || |
|Fentanyl ||2-3 mcg/kg IV || ||30-60 sec ||30-45 min |
|Lidocaine ||1-1.5 mg/kg IV || ||45-90 sec ||120 min |
|Sedation || || || || |
|Etomidate ||0.3 mg/kg IV || ||30-60 sec ||3-5 min |
|Midazolam ||0.1-0.3 mg/kg IV ||Benzodiazepine ||60-90 sec ||15-30 min |
|Thiopental ||3-5 mg/kg IV ||Barbiturate of choice ||< 30 sec ||5-10 min |
|Propofol ||2-3 mg/kg IV || ||15-45 sec ||3-10 min |
|Ketamine ||1-2 mg/kg IV || ||30-60 sec ||5-10 min |
|Paralysis || || || || |
|Succinylcholine ||0.3-2 mg/kg IV ||Depolarizing agent ||45 sec ||4-6 min |
|Rocuronium ||0.6-1.2 mg/kg IV ||Nondepolarizing ||< 1 min ||30-60 min |
|Vecuronium ||0.08-0.1 mg/kg IV ||Nondepolarizing ||2 min ||45-65 min |
The procedure of RSI and intubation can cause undesirable physiologic changes. Pretreatment is used to help blunt the negative effects. Pretreatment medications should be given 3-5 minutes prior to RSI.
The use of atropine as a pretreatment for intubation in pediatric intubation is controversial. Atropine has traditionally been used in tracheal intubation to depress the heightened vagal response (bradycardia) of pediatric patients. However, some studies have shown an increase in tachycardia and cardiac arrhythmia in patients who were administered atropine as pretreatment for intubation.
Patients who require intubation and have sustained head trauma or are otherwise at risk for increased intracranial pressure (ICP) may benefit from pretreatment measures designed to lower ICP. Classically, lidocaine and fentanyl have been used. Lidocaine is believed to decrease the cough reflex and prevent elevation in ICP. Fentanyl is an opioid analgesic that can blunt the sympathetic response to intubation. A defasiculating dose of rocuronium or vecuronium may also be given at 1/10th the standard paralytic dose to prevent fasiculations and subsequent elevation in ICP.
The use of etomidate in RSI remains controversial. Studies have shown that the use of etomidate can result in adrenal suppression and therefore have the potential to cause complications in children with septic shock. It is unclear if such complications will occur after administration of a single dose. Other studies support the efficacy of etomidate as a sedation treatment for RSI in children. Etomidate is still a widely used induction agent due to its relative hemodynamic stability.
Of the benzodiazepines, midazolam is the most commonly used for induction. Midazolam has the potential to cause respiratory depression and may have some undesirable hemodynamic effects. Benzodiazepines can be reversed with flumazenil, however this may reduce the seizure threshold.
Thiopental is a drug capable of induction of sedation for RSI. Thiopental has been used in patients with elevated ICP who are hemodynamically stable. The adverse effects of thiopental include histamine release, myocardial depression, venodilation, and hypotension.
Propofol is a powerful sedative/hypnotic, and may depress pharyngeal and laryngeal muscle tone to allow for ease of tracheal intubation. The use of propofol can cause hypotension and myocardial depression. Propofol does not have strong analgesic properties, and may cause pain upon infusion.
Ketamine is an n-methyl-d-aspartate (NMDA) receptor antagonist that has a wide range of effects including analgesia and anesthesia. Ketamine is one of the few RSI induction agents that will also cause analgesia in addition to its sedative effects. The adverse side effects of ketamine include possible increased heart rate and blood pressure, and this drug should be used with caution in patients who are hypertensive.
Neuromuscular Blocking Agents (Paralytics)
Succinylcholine is a depolarizing agent and recommended by many sources for neuromuscular block in RSI. Although succinylcholine is the most widely used medication for paralysis, it is not without adverse effects. Succinylcholine can potentially cause hyperkalemia, muscle fasiculations, and increased intraocular pressure. The potential for hyperkalemia restricts the use of succinylcholine for patients with malignant hyperthermia, hyperkalemia, recent burn or severe infection, denervating injuries, acute lateral sclerosis (ALS), or multiple sclerosis. In young children, the administration of succinylcholine in undiagnosed myopathies may leave patients at risk of hyperkalemia.
Despite its drawbacks, it has a faster onset of action and far shorter duration of effect than the nondepolarizing agents. This can be advantageous in a patient in whom there is a risk of failed intubation, especially if that patient is otherwise spontaneously breathing, or would be difficult to ventilate by other means if paralyzed for an extended period.
Rocuronium is part of a class of agents known as short-acting nondepolarizing neuromuscular blockers. Rocuronium exhibits less danger for hyperkalemia than succinylcholine. However, it has a longer time of onset and duration of effect. A physician may elect to give higher doses to shorten the onset of paralysis, however the duration of effect will also be lengthened.
Vecuronium is a nondepolarizing medication that acts similarly to rocuronium. Vecuronium also has a relatively longer onset and duration of action compared with succinylcholine.
Direct laryngoscopy can be used to assist in the visualization of the larynx for endotracheal intubation. Before intubation, all equipment, including suction, light bulbs on laryngoscope blades, and cuffs on ETT should be checked. The patient is placed in as ideal a position as possible (see Figure 9-7). The patient is given pretreatment and rapid sequence medications as indicated. The laryngoscope blade is held in the left hand. The right hand is used to part the lips and teeth. The laryngoscope blade is inserted along the right side of the mouth, sweeping the tongue to the left. Using the laryngoscope, the jaw, tongue, and epiglottis are lifted upward, taking care not to rock the laryngoscope backward and leverage against the upper teeth or maxilla. The vocal cords are visualized, and the appropriate ETT is inserted between them. The ETT is inserted to an appropriate depth, an initial estimation of which can be made by taking the diameter of the tube (in mm) and multiplying by 3. This will give an initial depth in centimeter. However, the position of the tube must be verified.
Tube Placement Verification Methods
The verification of ETT placement is a critical step in the intubation procedure. The possibility of misplacement can lead to hypoxic brain injury and death in a pediatric patient. It is important to note that no single verification method is 100% reliable and sensitive. Multiple methods should be considered and utilized in a patient to confirm the proper execution of endotracheal intubation. Verification should be repeated in patients who are moved or transported.
Visualization of the ETT passing through the vocal cords provides strong evidence of proper placement. However, difficult intubations under emergent conditions can limit and prohibit direct visualization.
Auscultation of equal breath sounds in the lungs can indicate proper ETT placement. The juxtaposition of the esophagus to the trachea in a pediatric patient can create sounds that may mask an esophageal intubation. During BVM-induced ventilation, breaths auscultated over the patient’s bilateral axillae are reassuring; however, breaths heard over the stomach indicate improper placement of the tube.
The rising and falling of a child’s chest may indicate proper ETT placement, however esophageal ventilation has also been shown to produce a similar chest rise.
Condensation seen in the ETT may be seen with tracheal placement. This method is considered unreliable because of the occurrence of water vapor in misplaced esophageal tubes.
Esophageal Intubation Detectors
Esophageal intubation detectors (EIDs) are more reliable than auscultation or chest rise for patients that are in cardiac arrest or are hypotensive. Self-inflating bulbs can be placed on an ETT and will inflate rapidly if correct placement is made. The absence of inflation or inflation taking longer than 5 seconds will indicate the necessity for ETT reassessment. Self-inflating bulbs are not recommended for children younger than 5 years or who weigh less than 20 kg.
A colorimetric device can be placed on an ETT to identify the presence of exhaled carbon dioxide. Patients who have been successfully intubated will exhale enough carbon dioxide to cause a color change from purple to yellow. In patients receiving humidified gas, the colorimetric device can be rendered useless within 15 minutes. The device contains paper that changes color in an acidic environment. Several conditions can cause difficulties in using a colorimetric device, such as the endotracheal administration of epinephrine, status asthmaticus, large glottic air leak, and acidic contamination.
Capnography is the detection of end-tidal CO2 on a breath-to-breath basis using measurements made by infrared spectrometry. Strong constant waveforms indicate proper tracheal intubation. There is a danger of false positives in patients who are bag-valve-mask ventilated and have had ETT placement in the pharynx. In the prehospital setting, capnography has been found to be more reliable than auscultation in the verification of ETT placement. However, end-tidal CO2 detection as a whole is less accurate in patients who are in cardiac arrest.
Intubation is considered successful if the tip of the ETT is between 2 and 6 cm above the carina, subject to variation with patient size. Verification of placement in the trachea can be made via a chest x-ray (CXR) to rule out placement in the esophagus. Chest radiographs are taken traditionally from anteroposterior view with the patient in the supine position and the head midline. Chest radiography is often discouraged as sole confirmation of correct ETT placement in an emergent setting because of the amount of time necessary to complete the procedure.
The most common complications of endotracheal intubation include esophageal intubation, aspiration, dental trauma, laceration to the oral airway, and hypoxia. Esophageal intubation increases the risk of gastric inflation and oxygen deprivation in the patient. Hypoxia can lead to tissue and cerebral damage, bradycardia, arrhythmia, and death. Proper tube placement verification methods identify most improperly placed ETTs.
Alternative Methods to Secure the Airway
A laryngeal mask airway (LMA) can be a successful alternative in patients who are difficult to intubate. It should be considered in situations where bag-mask ventilation and intubation are difficult or not possible. An LMA is usually placed in a patient’s pharynx and is subsequently easier to manage in an emergent setting. A balloon cuff is inflated to create a seal to establish a clear airway. A higher rate of complication has been noted in children compared with adults in the clinical setting. However, LMA is preferred over endotracheal intubation when a skilled practitioner is unavailable for endotracheal intubation. Relative contraindications for LMAs include unsedated patients and children with clear gag reflexes.
An LMA can also be used as a channel to assist in the tracheal intubation of a patient. Intubating laryngeal mask airways (ILMAs) provide specific features that can assist during intubation. An ILMA allows for larger ETT, a removable circuit connector, and the ability to lift the epiglottis. An ETT may be channeled through an LMA or ILMA to facilitate access to the trachea.
Cricothyrotomy (also called cricothyroidotomy) is an emergency procedure used to create a patent airway between the cricoid and thyroid cartilage. It is generally indicated in conditions where intubation or ventilation is contraindicated or cannot be performed. Cricothyrotomy may be performed on patients who are expected to have a difficult airway as determined by preprocedure tests. Serious complications of cricothyrotomy make it the “last ditch effort” in oxygenating a patient in acute distress. It has few absolute contraindications beyond that of accessibility and/or identification of the cricothyroid membrane. Two different methods of cricothyrotomy are available for short-term emergent use: surgical and needle.
Indications for cricothyrotomy include
Surgical cricothyrotomy is indicated for patients older than 12 years who meet the criteria for emergent ventilation as listed above. It allows for ventilation and oxygenation. Identification of the cricothyroid membrane is the first step in the procedure. A midline incision should be made on the cricothyroid membrane while avoiding the branches from the inferior thyroid and anterior jugular veins. The incision should be deep enough to gently enter the tracheal space. A tracheal hook may be used to maintain the tract to the trachea. The tracheostomy tube is then placed through the membrane. Care must be given not to insert the tube too far, because it can easily pass the carina and into a main bronchus. There are a number of commercially produced cricothyrotomy kits.
Tube size will be smaller than that used for orotracheal intubation to allow for the diminished cricothryroid space. A 6.0 ETT is often used in adult-sized patients. For smaller pediatric patients, a 4.5-5.5 ETT may be used. The ETT should be cuffed. The cuff allows some flexibility in tube selection if a slightly smaller size is chosen, but the largest size that can easily and safely be passed will allow for improved airway resistance and pulmonary toilet.
Needle Jet Cricothyrotomy
Needle jet cricothyrotomy is the preferred method used in patients younger than 12 years. A needle jet cricothryotomy is very similar to the surgical technique except for the use of a needle to puncture and gain access to the trachea. A syringe with approximately 1-2 mL of saline solution is mounted on a large bore (14-16 gauge) IV catheter with needle. The cricothyroid membrane is punctured, and angled at a 45-degree angle, pointed inferiorly. The needle is advanced while withdrawing with the syringe. Once the trachea is reached, air will be aspirated into the syringe. The catheter may be slid over the needle into the trachea. Many commercially available IV catheters have relatively flimsy plastic walls, and care must be taken not to kink them. Alternatively, if a kit is used, a small incision is then made to create a larger opening. A guide wire is fed through the needle and the needle is withdrawn. A dilator and subsequently a catheter are placed over the wire.
Once the catheter is secured, it must be attached directly to wall oxygen (not through a regulator) via tubing with a release valve. Alternatively a hole may be cut into the tubing small enough for a thumb to occlude which may serve as a pressure release valve. The patient should receive 1 second of jetted, pressurized 100% oxygen for every 4 seconds of pressure release. The patient is not effectively ventilated during this time. This is a temporizing measure only to allow for other definitive airway management techniques to be initiated.
Complications of cricothyrotomy are numerous and serious, including
Multiple modes of ventilation are available for postintubation care in the pediatric patient. Ventilator management is an extensive topic, covered briefly below.
Volume controlled ventilation (VCV) uses a set volume as the marker for cycling the ventilator. The ventilator functions by delivering constant volumes of inhalation to the patient. Improperly managed VCV may result in excessive pressure, especially under conditions of decreased compliance and may result in ventilator induced lung injury.
Care must be taken, especially in small children, if VCV is used. The volumes used in such patients are small. When the volume of the tubing and the rest of the circuit is added, the margin of error in many ventilators may not be within sufficient limits to avoid barotrauma.
Pressure controlled ventilation (PCV) delivers pressure to the patient as the driving force for ventilation. The volume that a patient receives is a function of the pressure administered, as well as other factors such as lung compliance.
Studies suggest some advantages of PCV over VCV. Airway pressures can be better controlled in patients who receive PCV over VCV, resulting in less lung injury.
Sedation after intubation is necessary when the duration of action of paralytic drugs outlasts the induction medication. A study of short-acting etomidate and rocuronium or vecuronium in pediatric patients showed that patients experienced inadequate sedative effects in the presence of paralysis. Emergency physicians should be aware of drug duration during RSI to avoid having a paralyzed patient who is not appropriately sedated. This is particularly apparent when using the longer lasting paralytics such as rocuronium or vecuronium.
Postintubation sedation also helps with patient comfort and ability to tolerate the ventilator. It can help reduce airway pressures and be beneficial for hemodynamics. Commonly used emergency department sedation regimens include intravenous (IV) continuous drips of fentanyl, versed, propofol, and ketamine.
Suction catheters are used in postintubation care to prevent aspiration. It is important to have a suction catheter available to remove any secretions in the oral cavity, pharynx, or trachea. Installed and portable suction units provide varying vacuum forces and must be adjusted before use. Recommended maximum tracheal suction force is between 80 and 120 mm Hg in children. Suction catheters that are used via the ETT should not be inserted farther than the ETT to avoid tracheal trauma.
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