530 SECTION V Pediatric Critical Care Pulmonary subglottis leads to stridor and respiratory distress Various scales have been devised to quantify the severity of stridor and to document the progressio[.]
530 S E C T I O N V Pediatric Critical Care: Pulmonary subglottis leads to stridor and respiratory distress Various scales have been devised to quantify the severity of stridor and to document the progression of the illness and its response to therapy One of the most commonly used scales is the Westley scale (Table 47.1), which has been validated.62,63 TABLE Westley Croup Score for Assessing 47.1 Croup Severity Clinical Findings Points Level of Consciousness Normal (including sleep) Disoriented/encephalopathic Cyanosis Absent With agitation At rest Stridor Absent With agitation At rest Air Exchange Normal Decreased Markedly decreased Retractions Absent Mild (nasal flaring) Moderate (suprasternal and intercostal) Severe (all accessory muscles used) Total score ranges from to 17 points and can be grouped into categories of mild (0–2), moderate (3–7), severe (8–11), and impending respiratory failure (12–17) Workup of a child with croup often involves chest and neck radiographs These will show a narrowing of the tracheal lumen that reaches its narrowest point in the subglottis just below the vocal cords, also known as the “steeple sign” (Fig 47.10) The upper glottis, which can be visualized on lateral neck radiographs, is normal Flexible laryngoscopy is not recommended in patients with an active croup infection as airway stimulation and agitation can further worsen edema and precipitate respiratory failure Supportive therapy should be maximized prior to any intervention A mixture of 80% helium and 20% oxygen (heliox) may be beneficial in severe cases because it permits greater gas flow past areas of narrowing than standard oxygen/nitrogen mixtures First-line medical therapy for an acute episode of laryngotracheobronchitis is nebulized epinephrine, which has been proven to measurably reduce airway inflammation and obstruction.64 This occurs as a result of a-adrenergic receptor stimulation in the trachea, which produces vasoconstriction and decreases edema Rebound edema may occur several hours later after the effects of the epinephrine dissipate Glucocorticoids are also beneficial adjuncts for treating croup.65 Oral, intramuscular, and nebulized corticosteroids have all been shown to be beneficial in randomized, blinded trials.66,67 They are proven to reduce the need for endotracheal intubation, hasten improvement in the first 24 hours of treatment, shorten the duration of admission, and reduce the frequency of readmission.59 Severe cases of croup may require endotracheal intubation The endotracheal tube (ETT) should be smaller than would normally be used to avoid additional injury to the swollen tracheal mucosa Medical treatment should be continued, and the ETT should be regularly checked for an audible leak When that is present, extubation can be attempted with a high probability that reintubation will not be necessary.68 If a leak does not become apparent after to days, an extubation trial should still be considered, because prolonged intubation may increase risk for subglottic injury Refractory or recurrent croup should raise suspicion for anatomic abnormalities, which are present in approximately 11% of children with multiple episodes of laryngotracheobronchitis.69 • Fig 47.10 Anteroposterior radiographs of the neck showing a normal tracheal air column (left, arrow- heads) and a subglottis narrowed by edema from laryngotracheobronchitis (right, arrowheads), giving it the characteristic “steeple sign.” (Courtesy Andrew Inglis Jr.) CHAPTER 47 Diseases of the Upper Respiratory Tract 531 • Fig 47.11 Epiglottitis causing a severely swollen epiglottis (arrows), necessitating endotracheal intubation (Courtesy Andrew Inglis Jr.) Epiglottitis Epiglottitis, also sometimes called supraglottitis, is an acute infectious inflammation of the upper airway that may lead to rapid respiratory decline and is often classified as an airway emergency (Fig 47.11) Haemophilus influenzae type B was once the most common cause of this infection However, with widespread use of the Hib vaccine in the past few decades, epiglottitis has become far less common.70 Currently, rates of infectious agents such as Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, and others have risen, although H influenzae is still a risk in unvaccinated patients.71 The classic presentation for epiglottis includes “the four D’s”— drooling, dyspnea, dysphagia, and dysphonia.72 Patients will typically be febrile, appear toxic and anxious, and may naturally position themselves in a tripod position (sitting upright, leaning forward, supporting themselves with the hands, mouth open) Neck and laryngeal palpation will be exquisitely tender Evaluation of a patient with suspected epiglottitis should proceed expeditiously Care must be taken to avoid agitating the patient and attempts to examine the oropharynx or place an intravenous line should be deferred If the patient is stable, a lateral neck radiograph can be obtained, which will classically show the “thumb sign” with thickening of the epiglottis (Fig 47.12).71 An otolaryngology consult should be obtained if available, and the child should be transported to the operating room as soon as possible The airway is typically secured with orotracheal or nasotracheal intubation after the patient is anesthetized, but the surgeon should always be prepared to perform an emergent tracheostomy, if necessary Cultures should be obtained to direct antibiotic therapy Intubation is often necessary for 24 to 48 hours to allow the swollen epiglottis to return to normal size Similar to laryngotracheobronchitis, extubation should be considered after an audible leak is heard around the ETT or after to days of endotracheal intubation.71 • Fig 47.12 Lateral radiograph showing a thickened, blunted epiglottis (arrow), also known as the “thumb sign.” (Courtesy Andrew Inglis Jr.) Bacterial Tracheitis Bacterial tracheitis is a rare condition that occurs as a secondary superinfection after a viral upper respiratory tract infection.73 Thick, membranous secretions coat the trachea, which not clear effectively with coughing S aureus is the most commonly isolated bacteria, accounting for 65% of cases.74 Frequently, but not always, bacterial tracheitis will resemble laryngotracheal bronchitis (croup); however, patients with bacterial tracheitis appear much more ill at time of presentation Unlike patients with croup, symptoms show little or no response to nebulized epinephrine Plain film radiographs may show hazy thickening of the trachea but are less valuable diagnostic tools than bronchoscopy Airway endoscopy is beneficial not only for diagnosis but also for obtaining cultures and clearing the airway of purulent debris75 (Fig 47.13) Antibiotics and respiratory support, sometimes with endotracheal intubation, are the mainstays of treatment Patients should be closely monitored for concurrent pneumonia, which occurs in 54% of cases.76 Peritonsillar Abscess The initial presentation of a peritonsillar abscess may mimic more serious airway infections Patients often present to the office or emergency department with fever, sore throat, muffled voice, and drooling Differentiating factors include lack of stridor and presence of otalgia and trismus On examination, the tonsil will appear erythematous, enlarged, and medialized, and may have an exudative covering Uvular deviation to the contralateral side of the pharynx may also occur If clinical suspicion is strong, imaging is not needed, and the clinician should proceed with treatment If a diagnosis is uncertain or if a patient has 532 S E C T I O N V Pediatric Critical Care: Pulmonary • Fig 47.13 Endoscopic photo of a patient’s airway with bacterial tracheitis Note the mucosal edema and mucopurulent secretions Rigid endoscopy can be both diagnostic and therapeutic, as secretions can be suctioned from the airway, alleviating symptoms of airway obstruction • Fig 47.14 Computed failed medical therapy, imaging may be a helpful adjunct In these cases, transcervical ultrasound or CT scan may be indicated.77 For an antibiotic-naive patient, medical therapy with intravenous or oral antibiotics should be trialed, as more than 50% of children with peritonsillar abscess will improve without procedural intervention.78 If a patient continues to worsen despite appropriate antibiotic treatment, either needle aspiration or incisional drainage in the operating room should be undertaken The most common bacteria isolated from peritonsillar abscess drainage are group A Streptococcus and Fusobacterium species.79,80 Retropharyngeal Abscess The retropharyngeal space lies deep to the fascial covering the posterior pharynx and esophagus It extends from the skull base superiorly to the mediastinum inferiorly and is fused in the midline with a lymph node chain on both sides These lymph nodes receive drainage from the nose, sinuses, pharynx, and eustachian tubes They generally regress with age but predispose pediatric patients to bacterial infection in this region when they become enlarged.80 Symptoms of a retropharyngeal space infection include dysphagia, muffled speech or cry, neck stiffness, and cervical lymphadenopathy Neck stiffness, or even torticollis, is much more likely to be seen in patients with abscess as opposed to just lymphadenitis.81 Posterior pharyngeal bulging may sometimes be seen, but the oral examination often is unremarkable A lateral neck radiograph often shows thickening of the prevertebral soft tissues, and an air-fluid level may be present CT scanning with contrast may also be employed in diagnosis of retropharyngeal abscess (Fig 47.14) Although important, the degree of prevertebral soft-tissue thickness and abscess dimension in a CT scan does not reliably predict the quantity of purulent material obtained at the time of surgical drainage.82 Similarly to peritonsillar abscess, antibiotic therapy may be attempted before surgery in the absence of respiratory distress.81 tomography scan of the neck with intravenous contrast of a patient with a left retropharyngeal abscess of considerable size causing airway compression and deviation Iatrogenic and Acquired Disorders of the Upper Airway Airway obstruction or damage may occur incidentally as a result of an unforeseen accident such as trauma, burns, or ingestion Especially in infants who may not be able to recount a history, a high suspicion on the part of the provider is critical for timely diagnosis and treatment Airway disease may also occur inadvertently as a result of medical interventions Many of these disorders result from scarring of the larynx or trachea from endotracheal intubation Knowledge of the pathogenesis of conditions can aid not only with treatment but also, more importantly, with prevention and is of particular importance to the critical care practitioner Laryngotracheal (Subglottic) Stenosis Laryngotracheal stenosis can present as a congenital airway obstruction, but far more often is a complication of prolonged or repeated endotracheal intubation.80,83 Injury occurs most commonly at the level of the cricoid cartilage, just below the vocal cords, at the level of the subglottis The cricoid is a complete circumferential ring of cartilage and therefore cannot expand under pressure This makes the subglottis particularly prone to edema, pressure necrosis, and scarring, which is why laryngotracheal stenosis is often synonymous with subglottic stenosis (SGS) ETT size plays an important role in pathogenesis of SGS Too large an ETT can compress the subglottic mucosa, leading to ischemia, necrosis, and, finally, scarring It was previously thought that cuffed ETTs may increase the risk of SGS, but more recent data suggest that, with careful monitoring of cuff pressure, they may actually be preferable.84–86 In addition to ETT size, factors such as individual susceptibility, movement of the ETT, presence of infection, and duration of intubation all play a role in laryngeal intubation injury The odds of prevention are enhanced by reducing CHAPTER 47 Diseases of the Upper Respiratory Tract the duration of intubation as much as judiciously possible and by choosing the smallest ETT size that will allow for adequate ventilation and pulmonary hygiene.83 SGS is often diagnosed when an infant presents with multiple upper respiratory infections These are often accompanied by biphasic stridor that worsens with agitation Presentation can mimic croup; therefore, providers should have a high index of suspicion when patients have prolonged or recurrent episodes.83 A detailed history is critical, especially regarding prematurity and past intubations The gold standard for diagnosis is operative laryngoscopy and bronchoscopy Voice and feeding evaluation should also be obtained in a patient with SGS as they may play an important part if subsequent surgery is needed SGS may be treated in a variety of ways, generally determined by the severity of the stenosis and related symptoms The most commonly used grading scale for SGS is the Myer-Cotton scale (Fig 47.15).84 A tracheostomy sometimes is needed as a temporary measure to bypass the obstruction The ultimate goal of surgical therapy is restoration of the airway and decannulation if a tracheostomy is in place Surgical treatments may include balloon dilation, endoscopic scar excision, cricoid expansion via cricoid split and cartilage grafts, and excision of the stenotic segment and reanastomosis via cricotracheal resection.85 Postoperative care of these patients, often in an intensive care setting, is critical Depending on the type of reconstruction, to 14 days are needed for the larynx and trachea to heal Some providers advocate for heavy sedation and neuromuscular blockade to minimize the chance of accidental extubation and trauma caused by the ETT, while others choose to keep the patient awake either with an ETT or tracheostomy in place.86,87 Classification From To No obstruction 50% obstruction Grade I Grade II 51% obstruction 70% obstruction Grade III 71% obstruction 99% obstruction Grade IV • Fig No detectable lumen 47.15 Myer-Cotton grading scale for subglottic stenosis (From Myer CM 3rd, O’Connor DM, Cotton RT Proposed grading system for subglottic stenosis based on endotracheal tube size Ann Otol Rhinol Laryngol 103[4 Pt 1]:319–323, 1994.) 533 Pediatric Tracheostomy Pediatric tracheostomies are placed for a variety of reasons, which can be generally grouped into three categories: airway obstruction, assisted ventilation, and pulmonary toilet Continued progress in neonatal medicine over the past few decades has resulted in survival of a greater number of premature newborns This has led to an increase in medical complexity of these very young patients, necessitating lengthy mechanical ventilation to treat infant respiratory distress syndrome and bronchopulmonary dysplasia While overall tracheostomy rates have remained stable, reason for placement has shifted significantly from infectious causes to need for prolonged respiratory support.88 As noted earlier, prolonged intubation increases the risk of subglottic stenosis and long-term airway compromise.83 Placement of a tracheostomy may prevent this complication The timing of tracheostomy placement depends on several factors, including the patient’s age, underlying illness, and severity of the condition that makes a tracheostomy necessary In many intensive care units (ICUs), tracheostomy is standard procedure in patients who are anticipated to need long-term respiratory support There is evidence showing that early tracheostomy placement in these patients leads to lower morbidity, shorter duration of mechanical ventilation, and shorter ICU stays.86,89–91,93 However, it should be noted that tracheostomies are not without risk Careful counseling and weighing of risk and benefit should take place prior to placement A review of the pediatric tracheostomy literature reveals a complication rate of 10% to 58% and a mortality rate of 0% to 3.6%.92,94 Complications can range from minor transient events, such as tube obstruction from mucous plugging, to more severe events, such as tracheal stenosis and tracheoinnominate fistula, although severe complications are very rare After a tracheostomy tube has been placed, careful postoperative care is essential Monitoring by attentive, well-trained providers can prevent many complications Until a tract has formed in the stoma between the cervical and tracheal epithelium, precautions must be taken to prevent accidental displacement of the tracheostomy tube Stay sutures are often placed in the trachea to assist with replacement in the event of accidental decannulation Even with these in place, replacement in an emergency situation with a struggling patient can be challenging A hasty replacement attempt may result in the cannula being incorrectly located in the pretracheal soft tissue (false tract) as opposed to the tracheal lumen, resulting in asphyxiation If positive-pressure ventilation is applied while the tube is in a false-tract position, subcutaneous emphysema will result, followed by mediastinal air dissection and even tension pneumothorax Because of these risks, patients routinely stay in the ICU for to days postoperatively If necessary, sedation can be given to reduce the risk of displacement while the stoma matures If accidental displacement does occur, replacement can be facilitated by attempting to visualize the tracheal lumen within the stoma before the tube is passed It is also important to remember that many tracheostomy patients can be intubated from above in case of emergency A patient is prepared for decannulation of the tracheostomy when the initial reason for placement has resolved or has been corrected It is common practice to undergo a formal airway evaluation in the operating room prior to tracheostomy removal to ensure the absence of other factors that would prevent a safe decannulation These factors may include vocal fold insufficiency, stomal granulation, suprastomal tracheal collapse, tracheal stenosis, or tracheomalacia.95 Closure of the stoma by secondary intention is 534 S E C T I O N V Pediatric Critical Care: Pulmonary • Fig 47.16 Endoscopic photograph during a rigid bronchoscopy showing • Fig 47.17 Chest radiograph demonstrating a radiopaque foreign body a portion of a nut that was aspirated into the right mainstem bronchus aspirated into the left mainstem bronchus preferred; an occlusive dressing is generally placed after tracheostomy tube removal to aid this Patients should be monitored in a hospital setting, often in an ICU, for at least 24 to 48 hours after decannulation before discharge visualize an AFB on a chest radiograph does not exclude the diagnosis For suspected cases, imaging should include inspiratory and expiratory radiographs, as a single anteroposterior radiograph will be unremarkable in 18% of patients with an AFB.100 If the foreign body produces ball-valve bronchial obstruction, hyperinflation of the involved lung will be seen during the expiratory image (Fig 47.18) The only definitive way to diagnose an AFB is with bronchoscopy, which is warranted any time clinical suspicion is high Bronchoscopy is both diagnostic and therapeutic, as the foreign body can be removed at the time that it is directly visualized Foreign Body Aspiration Foreign body aspiration is a common cause of airway obstruction in pediatric patients Although intervention techniques have significantly improved over time—along with lower mortality rates from foreign body ingestion—the overall incidence of foreign body aspiration has not recently changed.96 Nuts, seeds, and legumes (peanuts) are the most frequent offenders in children97 (Fig 47.16) The majority of patients seen for airway foreign body (AFB) aspiration are between ages of and years, and 95% are younger than age 10 years Children under years old are at the highest risk of mortality from AFB ingestion.98 Most foreign bodies pass through the laryngeal inlet and become lodged more distally in the airway, but 1% to 7% may present in the upper airway.99 These are predominantly items with irregular or sharp edges Once distal to the vocal cords, the most common location of AFBs is the right mainstem bronchus.96 This occurs due to its greater diameter as compared with the left and with its more acute angle in relation to the trachea When a pediatric patient aspirates a foreign body, it typically causes coughing, choking, and gagging, leading to obvious distress However, as the event is not always witnessed, diagnosis may be delayed in many patients It is estimated that only 30% of patients aspirating foreign bodies receive medical attention within the first 24 hours, and 20% to 50% are not detected for over a week.96,100 Symptoms after the inciting event may be subtle, manifesting as chronic cough or wheezing Due to the ubiquitous nature of these symptoms, other etiologies may be investigated before diagnosing AFB If left in place long enough, foreign bodies can cause pneumonia and may lead to bronchiectasis Initial workup for a foreign body should include a detailed physical examination and chest radiographs (Fig 47.17) Unfortunately, many foreign bodies are not radiopaque; thus, failure to Burn Injury to the Upper Airway Any patient being treated for burns is at a theoretical risk of thermal injury to the airway Luckily, the upper airway has efficient cooling capacity and only 15% of patients who present with burn injury have involvement below the vocal cords.101 The presence of facial burns, singed nasal hair, hoarseness, or stridor should raise suspicion for burn injury to the airway Respiratory compromise is not always present at time of initial evaluation but may develop later as swelling worsens Any evidence of respiratory symptoms in a burn patient should be investigated with neck and chest radiographs Nasolaryngoscopy has not been proven to change treatment outcomes (such as decision to intubate) for airway burn patients but can be helpful for evaluating extent of injury.102 Evidence of airway swelling on imaging or deteriorating clinical status should prompt endotracheal intubation to secure the airway Tracheostomy should be avoided in these patients if possible, as they are at an increased risk of infection.103 Even after acute injury has passed, inhalation injuries frequently have long-term consequences, such as dysphonia and airway stenosis.101 Airway Trauma Airway management is a key step in any trauma assessment but is particularly important for injuries to the head and neck Facial trauma can disfigure oral anatomy and make endotracheal intubation difficult Patients with obvious facial trauma are also at risk ... an airway emergency (Fig 47.11) Haemophilus influenzae type B was once the most common cause of this infection However, with widespread use of the Hib vaccine in the past few decades, epiglottitis... stable, a lateral neck radiograph can be obtained, which will classically show the “thumb sign” with thickening of the epiglottis (Fig 47.12).71 An otolaryngology consult should be obtained if available,... the ETT or after to days of endotracheal intubation.71 • Fig 47.12 Lateral radiograph showing a thickened, blunted epiglottis (arrow), also known as the “thumb sign.” (Courtesy Andrew Inglis Jr.)