1527CHAPTER 127 Airway Management around the mask and avoid gastric distention Therefore, it is not an optimal airway device in patients with severe subglottic airway obstruction, in those with parenc[.]
CHAPTER 127 Airway Management around the mask and avoid gastric distention Therefore, it is not an optimal airway device in patients with severe subglottic airway obstruction, in those with parenchymal disease requiring high ventilatory pressures, or in obese persons.151 It also is not the ideal technique to use in a patient with a full stomach because its design does not completely prohibit aspiration of gastric contents, although the seal is somewhat protective.152 However, in an emergency situation, the benefit of providing oxygenation and ventilation via an LMA outweighs the risk of an aspiration event Other scenarios that may limit placement of the LMA include excessive neck extension, limited mouth opening, or excessive application of cricoid pressure.151 Video Laryngoscopy Video laryngoscopy allows visualization of the larynx without requiring a direct line of sight aligning the oral, pharyngeal, and tracheal axes In adults with a difficult airway, video assistance improves visualization and permits more rapid intubation.153 Visualization in children is also improved, but evidence published to date suggests that the first-pass success rate is lower and time to intubation longer than with direct laryngoscopy, even when performed by experienced anesthesiologists, at least in patients for whom airway visualization is only moderately difficult.154–158 On the other hand, studies of simulated difficult airway management in infants have shown improved intubation rates without a longer time to intubation.156 At present, it appears that these devices may be most valuable in difficult situations—anticipated difficult airway, including cervical spine instability and craniofacial abnormalities, and unanticipated difficult or failed intubation—rather than as an advance in routine laryngoscopy.159,160 The video laryngoscope also provides a useful opportunity for teaching airway skills Some devices include laryngoscope blades similar to standard Mac and Miller blades A duplicate video image allows an instructor to view the attempted routine intubation in real time and provide immediate guidance and evaluation.161,162 Flexible Fiberoptic Bronchoscopy Flexible fiberoptic bronchoscopy is an effective means of securing a difficult airway, especially in patients with cervical spine instability or those in whom limited jaw mobility or oropharyngeal lesions prevent good visualization of the larynx.49,163 Assuming that the operator has clinical proficiency, the procedure is almost always successful, with little or no trauma to the patient The nasal route is routinely chosen because it is easier to use, better tolerated, and safer for the instrument than other routes A topical vasoconstrictive agent and local anesthetic are applied to the nasal mucosa The ETT is advanced through the nose into the nasopharynx, and the flexible scope is threaded through it The scope is advanced through the vocal cords, and the tube is passed over it into the trachea Alternatively, the tube with its connector removed may be threaded retrograde over the scope The scope is advanced through the nose, to the nasopharynx, and through the larynx into the trachea The ETT is advanced over the bronchoscope into good position The bronchoscopist then visualizes and secures the position of the tube in the trachea and carefully withdraws the scope The flexible fiberoptic bronchoscope also can be used with an intubating LMA While the LMA may not be used commonly in the pediatric ICU, it can provide an immediately accessible means of securing a difficulty airway and serve as a conduit to establishing a definitive airway Once adequate oxygenation and ventilation 1527 are established with prior LMA placement, a fiberoptic scope can be threaded through the LMA into the airway and an ETT advanced over it.164,165 Cricothyrotomy, Tracheostomy, and Retrograde Intubation Although airway management by endotracheal intubation is the appropriate first choice for most pediatric patients, intubation may not be possible and in some circumstances should not be attempted without surgical backup Such situations include massive facial trauma, oropharyngeal hemorrhage, epiglottitis, presence of a foreign body, and severe upper airway obstruction.166 In such circumstances, it is crucial that the surgical team be assembled and readily available to perform a tracheostomy in the operating room, time permitting A tracheostomy may be the preferred initial management strategy if the patient’s clinical status permits (tracheostomy is discussed in more extensive detail later in this chapter) Cricothyrotomy is an alternative to tracheostomy for rapidly establishing an airway in apneic or severely distressed patients The child’s head and neck are extended with a roll under the shoulders The cricothyroid membrane is palpated between the inferior margin of the thyroid cartilage and the superior edge of the cricoid cartilage With one hand (or an assistant) stabilizing the larynx and trachea, the clinician punctures the membrane in the midline with a large angiocatheter, withdraws the stylet, and connects the catheter to a source of oxygen using the connector to a size ETT Kits are available that facilitate cricothyrotomy with the Seldinger technique Oxygenation is rapidly improved in spontaneously breathing patients, but CO2 elimination is minimal Transtracheal jet ventilation is effective through such catheters provided that the upper airway permits passive exhalation; otherwise, severe hyperinflation and life-threatening barotrauma are certain Retrograde intubation can be accomplished using the aforementioned approach Once the cricothyroid membrane has been punctured and the catheter has been placed in the tracheal lumen, a long wire from a vascular access kit is advanced cephalad into the mouth With the wire firmly secure, an ETT may be advanced into the trachea Once the tube is in the tracheal lumen, the wire is withdrawn and the tube is advanced into the desired position If the wire is insufficiently stiff to permit passage of the tube into the trachea, an ETT exchanger can be advanced over the wire first, followed by the ETT In adults and adolescents, a small horizontal incision over the cricothyroid membrane is an alternative approach Once the membrane is incised, it is spread vertically, and a standard tracheostomy or ETT is inserted into the tracheal lumen This approach is not recommended for infants and young children except in highly skilled hands of an otolaryngologist because of the potential for grave injury to a small, soft trachea or nearby neurovascular structures Complications are similar to those of tracheostomy Complication rates of 10% to 40% are reported in adults.167 The available literature pertaining to pediatric patients, particularly in younger children, comprises mostly case reports Extubation Extubation is appropriate when the conditions for intubation are no longer present In general, this means that the work of breathing has decreased to a level manageable by the patient In most cases, ideal conditions for extubation occur when oxygenation is adequate with the administration of 40% oxygen or less; spontaneous tidal volume is greater than 3.5 mL/kg; the patient can 1528 S E C T I O N X I V Pediatric Critical Care: Anesthesia Principles in the Pediatric Intensive Care Unit sustain a normal Paco2 with a near normal respiratory rate for age without mechanical breaths or use of accessory muscles; secretions are manageable; upper airway reflexes are intact; and neuromuscular function is sufficiently good to achieve an adequate vital capacity and maximum inspiratory pressure.168 Although standard teaching suggests that extubation is most likely to be successful when there is an air leak around the ETT at less than 30 cm H2O, research indicates that the presence or absence of a leak is a poor predictor of extubation success.169 If intubation was for relief of upper airway obstruction, a direct inspection showing more normal anatomy is of particular value, and the significance of a leak may be greater In patients who previously had a difficult-tomanage airway, extubation over a tube changer or in the operating room, with surgical support available, should be considered.170 Before extubation, the child is put on NPO status for to hours depending on the nature of the medications and feeds (clears vs formula) If the child is on nasoduodenal feeds, a shorter time may be considered The tube and pharynx are suctioned thoroughly, and the child is ventilated with 100% oxygen to provide a reservoir of oxygen as a buffer against laryngospasm at extubation With the lungs fully inflated, the ETT is removed, and the child is provided with humidified oxygen and observed closely Postextubation stridor is common and may range from mild to life-threatening Children younger than years are most frequently affected by postextubation stridor Factors contributing to airway edema include a tight ETT or cuff, traumatic or repeated intubations, excessive movement of the tube (or patient), preexisting airway abnormalities, and airway infection.171 Cool mist or humidified oxygen is sufficient treatment for children with mild symptoms Nebulized racemic epinephrine (0.5 mL of a 2.25% solution in 2.5 mL of saline solution delivered intermittently or continuously) effectively relieves more severe upper airway obstruction in most children, probably by local vasoconstriction Only the l-isomer in the racemic formulation is biologically active Epinephrine available for cardiovascular use is as safe, effective, and less expensive if half the racemic dose is used After its use, edema may recur; thus, close observation must continue The value of corticosteroids is more controversial, in part because most studies not differentiate multiple causes of croup.172–180 Patients at high risk for postextubation stridor (e.g., those with multiple intubation attempts) appear most likely to benefit.175–177 Dexamethasone (0.25 mg/kg per dose every 4–6 hours for doses total) is recommended in selected cases The work of breathing through a narrowed upper airway can be decreased by inhalation of a low-density gas mixture Oxygen in helium is less dense than air or pure oxygen and permits higher inspiratory flow at lower resistance Helium-oxygen mixtures are commercially available, usually providing 20% oxygen in 80% helium More oxygen can be added to the mix as needed Although traditional teaching holds that at least 70% helium is necessary to decrease airway resistance enough to make a clinical difference in the work of breathing, experience demonstrates value at considerably lower concentrations If pharmacologic treatment is ineffective, noninvasive ventilatory support may prevent the need for reintubation, but meticulous attention to the patient’s work of breathing is critical to recognize potential catastrophic airway obstruction Reintubation with a smaller tube for 12 to 24 hours may be necessary Continued dexamethasone treatment and sedation to minimize agitation and additional airway trauma may permit resolution of symptoms Persistent symptoms are an indication for bedside flexible nasal endoscopy or diagnostic laryngotracheobronchoscopy in the operating suite Complications of Endotracheal Intubation Complications of intubation can be divided into those related to placement of the artificial airway, those that occur while the ETT is in place, and those related to extubation or appearing late (Table 127.4) Immediate complications usually are related to the underlying disease process; the physiologic effects of laryngoscopy, intubation, and administration of positive pressure; or direct trauma to airway structures The child’s general condition, TABLE 127.4 Complications of Endotracheal Intubation Immediate Maintenance Extubation/Late Hemodynamic instability Obstruction Laryngospasm Dysrhythmias Sinusitis Gagging, vomiting Apnea Otitis (similar to immediate) Aspiration Physiologic g PAO2 Sore throat h PaCO2 Dysphonia, aphonia Coughing Laryngospasm Gagging, vomiting, regurgitation, aspiration h Intracranial pressure h Intraocular pressure Traumatic Nasal septum laceration, perforation Lip, tongue ulceration Laryngeal or tracheal granuloma Nasal turbinate injury Nares ulceration Vocal cord paralysis Tooth loss or injury Palatal erosion, cleft formation Subglottic stenosis Lip, tongue, palate laceration, hematoma Vocal cord edema, ulceration Tonsillar or adenoid avulsion, laceration, hematoma Laryngeal and tracheal mucosal ischemia, ulceration, necrosis Laryngeal strictures Recurrent laryngeal nerve damage Cervical spine subluxation Subglottic edema, ulceration Malposition Esophageal Mainstem intubation Mainstem bronchus Inadvertent extubation Intracranial Atelectasis Soft tissue CHAPTER 127 Airway Management tube size, cuff pressure, movement, airway infection, systemic perfusion, duration of intubation, and attention to meticulous airway care are factors that influence the development of problems during maintenance of the airway.181 Laryngospasm, aspiration, and failure (or inability) to deflate a cuff cause complications at extubation Although laryngeal or tracheal injury may be obvious at the time of intubation, symptoms may be delayed to weeks Prolonged Intubation The safe duration of endotracheal intubation in infants and children is not clear Since the 1950s, the accepted period has increased from less than 12 hours to an undefined much longer period Subglottic stenosis is reported to occur in 1% to 8% of infants after prolonged intubation, but a similar incidence has been noted after intubation for less than week.182 In older infants, children, and adults, it is becoming evident that there is no clear safe period Complications can occur immediately at intubation or may not be seen until many weeks or even months of ETT use.183 The decision to transition to tracheostomy should not be based on an arbitrary time limit but rather on the relative advantages and disadvantages of one artificial airway over another in each individual patient Tracheostomy Indications for tracheostomy include structural abnormalities of the upper airway requiring surgery, laryngeal trauma or complex craniofacial injury, severe facial burns, congenital anomalies lacking surgical treatment, vocal cord paralysis, and iatrogenic injury to the upper airway Severe chronic neurologic dysfunction with impaired protective reflexes is an additional indication Even without evidence of upper airway damage, tracheostomy may be performed to provide a more comfortable airway, which simultaneously provides airway protection and respiratory support, decreases sedation needs, and allows greater patient mobility Greater mobility is advantageous, especially for those undergoing chronic ventilation, because it enables patients to engage in early rehabilitation during which nutritional, developmental, and psychosocial needs may be met.184–187 Adult studies are increasingly supportive of early tracheostomy placement over late placement, with benefits including decreased ICU length of stay, reduction in duration of mechanical ventilation, decreased incidence of ventilatorassociated pneumonia, and decreased mortality Pediatric studies are much smaller and have mixed results but seem to favor early tracheostomy placement as well.188–190 Tracheostomy spares laryngeal and subglottic structures from the trauma of an artificial airway, particularly in active or thrashing patients Tracheostomy tubes are less likely to be inadvertently dislodged or to become obstructed, but if either problem occurs early after tracheostomy, it is more likely to be catastrophic Because the tube is inserted below the cricoid ring, it is often possible to use a larger tracheostomy tube rather than an ETT Nevertheless, a larger leak around the tube may interfere markedly with effective ventilation in patients who require high airway pressures Complications in the early postoperative period include bleeding, subcutaneous air dissection, pneumothorax, pneumomediastinum, injury to the recurrent laryngeal nerve, and death, usually as a consequence of lost airway control intraoperatively or an unrecognized complication from the preceding list Nearly all 1529 pediatric patients can and should be intubated before tracheostomy Prior intubation decreases the incidence of most technical problems Exceptions include patients with complex facial or airway injuries or deformities and those in whom no other means of establishing an airway have been successful and placement is emergent in nature Wound colonization occurs rapidly Bacterial infection may occur, rarely involving major cervical and mediastinal structures Swallowing difficulty is common and may result from the tube and fixation tapes, limiting excursion of the larynx Aspiration may result from alteration of the laryngeal closure reflex Tracheostomy tube obstruction or accidental dislodgment is suspected when the patient becomes agitated and shows signs of increased respiratory distress, a suction catheter no longer passes freely, manual ventilation is ineffective, or, in case of dislodgment, the child is suddenly able to vocalize In such cases, the tube should be removed and replaced with a new one The child is placed supine with the head and neck extended Oxygen is delivered to the nose, mouth, and tracheal stoma If manual ventilation is necessary, the stoma can be occluded to allow bag-mask ventilation as previously described A fresh tracheostomy tube is inserted, initially directed posteriorly and then caudad Replacement with a smaller tube or ETT may be necessary if resistance is encountered Resistance to passage of a suction catheter or ineffective ventilation after replacement of a tracheostomy tube, particularly in the first to 10 days postoperatively, is highly suggestive that a “false passage” has been created in a tissue plane outside the tracheal lumen Pediatric otolaryngologists will often leave stay sutures in place for fresh tracheostomy placements as a safety measure to help avoid false passage in case a new tracheostomy dislodges Stay sutures can be pulled to tension, effectively pulling the trachea flush to the skin, allowing the provider to replace the tracheostomy tube Reestablishing tracheal cannulation may require surgical intervention if this fails Life-threatening pneumothorax or pneumomediastinum occurs frequently in such patients Late complications include granuloma or stricture formation at the stoma or where the tip of the tube meets the tracheal wall Persistent posterior wall pressure may cause tracheoesophageal fistula formation Erosion into the innominate artery is another rare occurrence, usually when the tracheostomy incision is below the third tracheal ring The importance of having an experienced, well-trained staff immediately available to address problems is supported by data showing that mortality related to tracheostomy is significantly lower when performed in a children’s hospital and decreases with increasing volume.191 Decannulation occurs when the indications for tracheostomy are no longer present Diagnostic laryngotracheobronchoscopy before a planned decannulation enables practitioners to identify problems likely to interfere with effective breathing, including granulation tissue, severely stenotic areas, or vocal cord abnormalities If none is present, the indwelling tube is replaced with successively smaller tubes until the smallest available is in place and the child is breathing well If no distress occurs, the tube is removed and the stoma is covered It is noteworthy that in recent years, as patients with significant chronic conditions and cerebral disabilities live longer and the lives of many are prolonged by tracheostomy placement with or without mechanical ventilation, ethical discussions have been sparked regarding how to best serve them Studies show that 90% of patients receiving tracheostomies in North American pediatric ICUs have significant chronic conditions and that 50% have 1530 S E C T I O N X I V Pediatric Critical Care: Anesthesia Principles in the Pediatric Intensive Care Unit moderate or worsening cerebral disability Incidence of and practices surrounding tracheostomy vary significantly between sites Physician attitudes, family beliefs, and availability of multidisciplinary teams all can play a role.192,193 Long-term follow-up studies on the morbidity, mortality, and decannulation rates in this patient population are slowly becoming available and will be important as practitioners hold informed consent discussions with caregivers regarding their loved ones.194 Special Circumstances Full Stomach Patients with a full stomach are at high risk for aspiration of gastric contents during airway manipulation, particularly if protective airway reflexes are impaired This impairment may have iatrogenic causes from induction drugs administered by the intensivist or result from neurologic sequelae of the disease process Much of the morbidity associated with aspiration can be attributed to the effects of acid aspiration Aspiration of fluid with a pH below 1.8 is associated with a high incidence of severe pulmonary dysfunction and death Aspiration of fluid with a pH between 1.8 and 2.5 produces symptoms of moderate severity When fluid with a pH above 2.5 is aspirated, sequelae are less a consequence of the acid than of other characteristics of the material aspirated.195 Other risk factors include the volume aspirated, the presence and nature of particulate food particles, contamination by bacterial pathogens, underlying pulmonary or systemic disease, and immunosuppression.196 Food particles may physically obstruct small or even large central airways and cause alterations in lung volume in segments distal to the obstruction In addition, certain foods may cause severe local inflammatory changes Bacterial contamination of the upper gastrointestinal tract secondary to bowel obstruction or even antacid administration greatly increases the risks of respiratory infection after aspiration Patients who have eaten shortly before intubation (,8 hours) should be assumed to have a full stomach.197 In addition, those with bowel obstruction, pharyngeal or upper gastrointestinal bleeding, trauma, or acute onset of illness within hours of eating and those who are pregnant, have ileus, or have tense abdominal distention from any cause should be considered to have a full stomach Emerging studies with point-of-care ultrasound have shown that some patients continue to have gastric contents even after the recommended NPO time198,199: • Clear liquids: hours • Breast milk: hours • Formula: hours • Light meal: hours • Heavy meal: hours Although delaying airway manipulation might be the measure most certain to prevent aspiration, this approach is not a realistic option in many situations confronting the intensivist In a conscious child, the volume of gastric contents can be minimized by suction through a relatively large-gauge nasogastric tube, but complete emptying of the stomach, particularly of large food particles and blood clots, is rarely possible Additionally, H2 antagonists and proton pump inhibitors effectively decrease both the volume and acid content of gastric secretions, but a 60- to 90-minute wait is required after administration before the effect becomes adequate Moreover, antacids, H2 blockers, and proton pump inhibitors not decrease the volume of gastric contents already present in the stomach Anticholinergic agents such as atropine or glycopyrrolate also reduce gastric acidity but slowly and less effectively than the H2 antagonists In addition, they may decrease gastroesophageal sphincter tone and appear to have no value in preventing the acid aspiration syndrome Antacids can effectively neutralize gastric pH However, when aspirated, particulate antacids (aluminum and magnesium hydroxides) produce inflammatory changes as severe as gastric acid and food particles Clear antacids, such as sodium citrate or AlkaSeltzer, appear to provide true protection They effectively increase gastric pH and, when aspirated, appear to produce damage no more severe than that caused by normal saline solution However, their use has not become common clinical practice.200 Intubation is at once protective of the patient vulnerable to gastric aspiration and itself a risk to the patient In an alert child with intact protective airway reflexes, it may be appropriate to pass a nasogastric tube to decrease the volume of gastric contents A clear antacid (e.g., sodium citrate, 10–30 mL) can be administered orally or through the tube, which then is removed In a child with impaired reflexes, no effort to pass a nasogastric tube should be made because of the risk of inducing vomiting or regurgitation with subsequent aspiration The intensivist should examine the patient’s airway to be as certain as possible that intubation will not be difficult, as discussed previously If intubation likely will be straightforward, a rapid-sequence induction (RSI) is indicated (Box 127.4) The goal of this intubation method is to minimize the likelihood of vomiting or regurgitation during the time between loss of protective reflexes and correct positioning of the ETT The sequence consists of preoxygenation; avoidance of positive-pressure ventilation, including bag-mask ventilation; administration of an intravenous sedative or anesthetic with immediate cricoid pressure; pharmacologic paralysis; and endotracheal intubation Properly • BOX 127.4 Rapid-Sequence Intubation for Full Stomach Indications Inadequate NPO time Pharyngeal or upper gastrointestinal bleeding Intestinal obstruction or ileus (includes acute onset of illness and trauma) Tense abdominal distention Pregnancy Relative Contraindications “Difficult” airway Profuse hemorrhage obscuring visualization Upper airway obstruction Increased intracranial pressure Procedure Prepare all necessary equipment, including suction devices Allow patient to breathe 100% oxygen for minutes Direct assistant to apply cricoid pressure Rapidly infuse anesthetic or sedative/analgesic and neuromuscular blocking agents intravenously Allow patient to continue to breathe oxygen until apneic Avoid manual ventilation to minimize gastric distention Perform laryngoscopy and orotracheal intubation with stylet in endotracheal tube Confirm endotracheal tube placement Release cricoid pressure NPO, Nothing by mouth CHAPTER 127 Airway Management applied, cricoid pressure decreases the likelihood of insufflation of gas into the stomach, which may prevent regurgitation of gastric contents into the trachea and improve visualization of the larynx201,202 (see Fig 127.9).105,203–205 On the other hand, excessive pressure may actually increase the likelihood of vomiting, occlude the trachea, or make visualization more difficult The patient spontaneously breathes 100% oxygen by mask for to minutes before further manipulation If the child can cooperate and has relatively normal gas exchange, four deep breaths provide a reasonable pulmonary reservoir of oxygen However, in patients with severe pulmonary parenchymal disease, improvement in oxygenation may be limited and require a longer period of oxygenation.206 If other factors in the child’s condition permit, next steps in the rapid sequence intubation should be delayed until hemoglobin saturation reaches 100% or oxygenation reaches a plateau Bag-mask ventilation or positive-pressure ventilation of any kind must be avoided for a true RSI and intubation to be performed Once preoxygenation is complete, the anesthetic or sedative is administered by rapid intravenous infusion, an assistant applies cricoid pressure immediately, and, as consciousness is lost, a muscle relaxant is given The mask supplying oxygen is kept in place until the patient becomes apneic Again, to avoid gastric distention and regurgitation, no effort is made to assist ventilation Once the patient is flaccid and apneic, the intensivist performs laryngoscopy and intubates the patient Use of a stylet in the ETT facilitates rapid intubation Only after correct tube position is verified and the tube cuff, if present, is inflated should cricoid pressure be relieved and manual ventilation begun If the intubation is unexpectedly difficult and the patient shows evidence of progressive hypoxemia, manual ventilation between attempts may be necessary but should be done with continued cricoid pressure Some centers use a high-flow nasal cannula for both preoxygenation and apneic oxygenation during RSI to avoid desaturation However, studies show mixed results at this time.207–211 Multiple combinations of drugs can be used for RSI/intubation, but the same principle must be applied They must have fast onset to achieve intubating conditions for an RSI Propofol, ketamine, or etomidate may be used as the intravenous anesthetic during an RSI They all have quick onset and should be chosen by pairing the presenting clinical scenario with the appropriate drug of choice based on its benefits and adverse effects as previously discussed Although sodium thiopental is also an ideal drug for RSI, it has been unavailable in the United States since 2011 Sedatives and analgesics such as benzodiazepines and narcotics should not be used for RSI given their nonideal duration of onset and inability to achieve adequate depth of anesthesia Succinylcholine or rocuronium may be used as NMBAs during an RSI Succinylcholine classically produces ideal intubating conditions rapidly, but it has multiple adverse effects (as noted previously) that may make it an undesirable choice to the intensivist Rocuronium, when given at two times the usual intubating dose, produces good conditions for intubation nearly as quickly as does succinylcholine (45 s) and without adverse effects, but the effects last longer Rocuronium is the current best alternative, with its rapid onset and quicker reversibility with sugammadex.212 Sugammadex is now widely available in the United States and can be used to reverse the effects of rocuronium quickly if the intensivist encounters a “cannot intubate–cannot ventilate” scenario after induction as previously discussed in the difficult airway section Table 127.3 lists suggested drugs and doses Many patients encountered by the intensivist have poor pulmonary reserve and are at risk of desaturating much more rapidly and profoundly than non-ICU patients These include, but are 1531 not limited to, infants; patients with acute respiratory failure due to acute respiratory distress syndrome, pulmonary contusions, pneumonia, and so on; and patients with chronic respiratory failure caused by chronic lung disease, pulmonary hypoplasia, cystic fibrosis, and the like Patients such as these may not tolerate the period of apnea after induction that is required for a true RSI/ intubation In these patients, we may perform what is commonly referred to as a modified RSI The sequence of events is identical to that of a true RSI, but after administration of the induction medications and application of cricoid pressure, rather than apneic oxygenation, the patient is gently hand ventilated with small tidal volumes to minimize gastric insufflation This technique is used to avoid desaturation and subsequent hemodynamic instability that may be associated with poor pulmonary reserve Interestingly, this technique is referred to as modified rapid sequence; however, when RSI/intubation was initially described in 1951, mask ventilation was still part of the sequence It was not until 1963 that W.D Wylie suggested a period of apnea after induction.213–215 Increased Intracranial Pressure and Neurologic Dysfunction The intensivist is frequently called on to intubate children with severe central nervous system dysfunction resulting from infection, hemorrhage, trauma, hydrocephalus, or mass lesions, any of which may be associated with actual or imminent intracranial hypertension and herniation In most circumstances, the intensivist can observe signs of elevated ICP or recognize situations in which the likelihood is high, but there is no clinical measure of its severity Current guidelines recommend intubation for patients with a Glasgow Coma Scale score of or less.216 Intubation under these conditions should be undertaken with the recognition that it is a likely stimulus for further and potentially lethal intracranial hypertension The most immediate method of lowering ICP is to decrease CBF (volume) through hyperventilation Unfortunately, the process of intubation has the potential to decrease minute ventilation and increase cerebral blood volume even when performed with great caution and preparation Under normal circumstances, CBF is closely coupled to the cerebral metabolic oxygen requirement (CMRO2) Cerebral oxygen consumption and blood flow increase with increasing body temperature, motor activity, pain or other noxious stimuli, and seizure activity Blood flow also increases rapidly when Pao2 falls below 50 to 60 mm Hg and linearly as Paco2 increases over a wide range With intact autoregulation, blood flow is independent of systemic blood pressure except at very high or low levels However, when autoregulation is impaired, mean arterial pressure may affect CBF over a much broader range Elevated intrathoracic pressure during struggling, coughing, or Valsalva maneuvers may impede jugular venous drainage and result in intracranial venous congestion Laryngoscopy and intubation are powerfully noxious stimuli In the awake, unsedated child and even in the severely obtunded patient, laryngoscopy and intubation likely will precipitate vigorous struggle, coughing, pain (anxiety), and marked evidence of autonomic stimulation.29,42,43,217 In most patients, sympathetic discharge predominates, with tachycardia, hypertension, and diaphoresis In the infant, vagal stimulation often predominates, with resulting bradycardia Even in the lightly anesthetized patient, laryngoscopy itself and then intubation are associated with hypertension, tachycardia, and increased ICP As might be predicted, massive surges in ICP are more likely to occur in patients suspected of having borderline or high baseline ICP before intubation than in those who have ... gastric insufflation This technique is used to avoid desaturation and subsequent hemodynamic instability that may be associated with poor pulmonary reserve Interestingly, this technique is referred... necessary to decrease airway resistance enough to make a clinical difference in the work of breathing, experience demonstrates value at considerably lower concentrations If pharmacologic treatment... support may prevent the need for reintubation, but meticulous attention to the patient’s work of breathing is critical to recognize potential catastrophic airway obstruction Reintubation with a smaller