Pediatric Tracheostomy

Background

Asclepiades is said to have performed the first tracheostomy in 100 BC. In the 19^th century, tracheostomy was first widely used in the treatment of diphtheria in children, and by 1887, approximately 20,000 of these operations had been reported in Western Europe and the United States.

The scope of the procedure broadened when Galloway reported using the procedure for the respiratory care of patients with poliomyelitis. It was the epidemic of poliomyelitis in the early 1950s that stimulated the use of tracheostomy for positive-pressure ventilation, and this opened the doors for similar treatment in tetanus, cardiac surgery, severe burns, and the care of preterm infants. ^{[1, 2]}

The incidence of and indications for pediatric tracheostomy have changed over years. Upper airway obstruction secondary to infectious disorders was once the most common indication for tracheostomy. ^[3] Currently, however, the most common indication for pediatric tracheostomy is prolonged ventilation necessitated by neuromuscular or respiratory problems. ^[4]

The old dictum that tracheostomy should be performed as soon as it comes to mind may not hold true now. This article outlines the indications for and performance of tracheostomy in children. It should be kept in mind that the indications and the timing may vary, depending on the facilities available in the institution where the patient is admitted, the comfort level of the medical team in postponing the tracheostomy, and the expertise of the individual surgeon in performing the surgery.

Indications

Vaccination programs, improvements in material engineering, and anesthetic skills have dramatically reduced the number of emergency tracheostomies performed for acute upper airway obstruction. Today, the main indications for tracheostomy in a child generally involves either (1) anticipated long-term cardiorespiratory compromise resulting from chronic ventilatory (or, rarely, cardiac) insufficiency or (2) the presence of a fixed upper airway obstruction that is unlikely to resolve for a significant period of time. ^{[5, 6, 7, 8]}

In one series, subglottic stenosis (31.4%), bilateral vocal cord paralysis (22.2%), congenital airway malformations (22.2%), and tumors (11.1%) were the most common conditions that necessitated pediatric tracheostomy. ^[9] Conditions that have increased the frequency of pediatric tracheostomy over the past decade include respiratory papillomatosis, caustic alkali ingestion, and craniofacial syndromes. Conditions in which tracheostomy are now used less frequently include subglottic hemangioma and laryngeal clefts. ^[4]

Contraindications

A tracheostomy is contraindicated during surgical repair of a type IV laryngotracheoesophageal cleft, because it may erode the posterior suture line and result in a breakdown of the repair. It is preferable to managing the airway with a nasotracheal or orotracheal tube during the postoperative period with the child kept paralyzed, although many children ultimately require tracheostomy when the repair is soundly healed because of tracheomalacia, which prevents extubation. ^[10]

Technical Considerations

Performing a tracheostomy is difficult in pediatric patients, because a child's neck is anatomically different from an adult's neck in the following ways:

• The dome of the pleura extends into the neck and is thus vulnerable to injury

• The trachea is pliable and can be difficult to palpate

• The trachea can be easily retracted to a great extent with little pull, and care must be taken distinguish it from the carotid vessels

• The neck is short, and there is significantly less working space

• The cricoid can be injured if it is not correctly identified

Preprocedural Planning

A key element of planning for tracheostomy is selection of the appropriate tube size. The optimal size of the tracheostomy tube depends on the clinical indications for the procedure and the size of the airway. ^[11] The tube should be small enough to allow the child to speak but not so small that a large insufflation leak causes hypoventilation, especially during sleep. ^[12]

Both diameter and length should be considered when a tracheostomy tube is selected. Using a tube with too large a diameter may injure the tracheal mucosa by compromising its vascular supply. The injury may result in ulceration and, ultimately, fibrous stenosis. Overinflation of a cuffed tracheostomy tube for a prolonged period may produce a similar injury. The tube should be long enough to allow adequate air entry, easy suctioning, and clearance of secretions.

If the child is being ventilated, a tube large enough to allow appropriate delivery of inspired gas without leaking should be selected. Pediatric tracheostomy tubes are cuffless. Cuffed adult tracheostomy tubes are sometimes used in large children and adolescents. The diameter of the tracheostomy tube can be estimated on the basis of the size (corresponding to the inner diameter) of the child’s endotracheal tube.

Wetmore recommends the following pediatric tracheostomy tube sizes, determined on the basis of patient age and weight ^[13] :

• Premature neonates or babies who weigh less than 1000 g - 2.5 mm

• Babies who weigh 1000-2500 g – 3 mm

• Neonates aged 0-6 months – 3-3.5 mm

• Infants aged 6 months to 1 year - 3.5-4 mm

• Infants aged 1-2 years – 4-4.5 mm

• Children older than 2 years – (age [years] + 16)/4

Unlike adults, children require progressively larger tracheostomy tubes as they grow. If this requirement is not addressed in a timely fashion, nocturnal dips in oxygen saturation can occur, or low-pressure ventilator alarms may be triggered. The necessary inner diameter of the tracheostomy tube steadily increases with the child’s increasing age. ^[14]

A retrospective study by Behl and Watt found that appropriate inner and outer diameters could be conveniently calculated by means of the following formulas ^[14] :

Inner diameter (mm) = (age [years]/3) + 3.5

Outer diameter (mm) = (age [years]/3) + 5.5

The inner and outer diameters of the tracheostomy tube correlated well with patient weight, as follows ^[14] :

Inner diameter (mm) = (weight [kg] × 0.08) + 3.1

Outer diameter (mm) = (weight [kg] × 0.1) + 4.7

As the child grows, the size of the tracheostomy tube should be increased as a planned procedure at least every 2 years to prevent nocturnal desaturation. Sex is not a factor in tube size. ^[15]

The length of the tracheostomy tube is also a critical variable, especially in neonates and infants. A tube that is too short may result in accidental decannulation or formation of a false passage. If the tube is too big, the end may abrade the carina or rest within the right main bronchus, thereby occluding the left. Custom tubes fashioned from an endotracheal tube may be helpful in cases where a standard tube is unsatisfactory. In neonates and infants, the same size tube is available in 2 lengths; therefore, selecting the correct length is important.

Equipment

A tracheostomy tube is a hollow tube, with or without a cuff, that is electively inserted directly into the trachea through a surgical incision or with a wire-guided progressive dilatation technique. A number of tracheostomy tubes are available for neonatal, pediatric, and adult uses. See Tracheostomy for a full discussion of tracheostomy tube options.

The unique attributes of neonatal and pediatric airways require special tubes. These range from 2.5-5.5 mm in internal diameter and have lengths ranging from 30-36 mm for neonates and 39-56 mm for pediatric patients. Because of their small size, only single-lumen tubes are used. To avoid buildup of secretions, these tubes need to be changed more frequently. Because of the delicate developing tracheal tissue and the narrow cricoid ring, cuffed tubes are not recommended and rarely required.

One way to choose a tube for pediatric patients is by calculating the estimated internal diameter: internal diameter = (age/4) + 4

Patient Preparation

In most cases (except in an absolute emergency), tracheostomies are performed with the patient under general anesthesia, intubated, and paralyzed. The patient’s neck is extended with a shoulder roll, and the head is stabilized with a ring under the occiput. Some surgeons prefer to use a bronchoscope to define the trachea and to ventilate the patient. Other tubes in the patient (eg, a nasogastric tube) are removed so that they will not be confused with the trachea during the operation.

Monitoring and Follow-up

Home care

Once the appropriate tube is chosen, tube care consists of tube change, fixation, management of secretions, humidification of inspired air, and the application of medications. The stoma requires cleaning, protection, and dressing. Preparing the home and family environment are important prerequisites for discharge from the hospital. Finally, the child’s family or other caregivers must undergo a structured and detailed training program to become competent in long-term home care. ^{[16, 17]}

The only reported complications of home care include partial obstruction of the cannula and accidental decannulation. The low rate of documented accidents, in addition to most parents' profound appreciation of having their children at home, indicates that patients who have undergone tracheostomy and who are in need of long-term care can generally be safely treated at home. ^{[18, 19, 20]}

Decannulation

Tracheostomy indications and patient diagnoses are significant variables in predicting the possibility of early decannulation in pediatric patients who require tracheostomy. ^[21] Successful decannulation after pediatric tracheostomy depends largely on the resolution or significant improvement of the primary underlying disorder for which tracheostomy was originally performed, as well as any secondary pathologic conditions (eg, persistent granulations) that may develop at the tracheostomy site. ^[16]

Reported risk factors for the failure of decannulation include a history of prematurity, dysphagia with a history of gastrostomy tube placement, craniofacial or genetic syndromes, hydrocephalus, and bronchopulmonary dysplasia. ^[22]

It has been suggested that the most common reason for failure of decannulation is peristomal pathology (ie, granulations, suprastomal collapse, stomal tracheomalacia, stenosis). ^[23] Methods of treating established suprastomal granulations include removal with a forceps or hook under bronchoscopic endotracheal visualization; however, this approach inevitably leads to localized bleeding, impaired visualization, and incomplete removal. Potassium titanyl phosphate (KTP) laser therapy is another method used to treat this problem. ^[24]

Creation of Tracheal Stoma

Lidocaine (1%) is used along with 1:100,000 adrenaline for infiltration. A horizontal incision is made halfway between the cricoid cartilage and the sternal notch (see the video below). Subcutaneous fat and tissues are reflected, the subcutaneous fat is removed with a bipolar cautery, and the deep cervical fascia is exposed. This fascia, in turn, is cut with the bipolar cautery to expose the thyroid isthmus, which is then also divided with the cautery. Sometimes, it is possible to expose the trachea by simply retracting the isthmus superiorly.

Nonabsorbable 4-0 stay sutures are placed through the tracheal rings on each side of the midline and are left in place even after surgery. These sutures are useful for applying traction to pull up and expose the trachea, and they can be lifesaving should accidental decannulation occur before the tract is established. Lateral retractors are removed, and the trachea is elevated with stay sutures. A vertical cut is made in 2-3 rings in the midline, and no part of the tracheal wall is removed.

Skin flaps can be sutured to the tracheal lumen for further safety; however, the author generally omits this step. The endotracheal tube or bronchoscope is withdrawn, and the tracheostomy tube is simultaneously inserted. The patency of the tube is checked. The stay sutures on each side are labeled and taped on the corresponding side of the chest. A tracheostomy dressing is placed, and postoperative neck and chest radiographs are obtained to evaluate the position of the tube and to identify any pneumothorax that may have developed.

There are 3 main precautions that must be observed during the procedure. First, to the extent possible, carry out the procedure with the endotracheal tube or bronchoscope in place. This helps in defining the location of the trachea and avoiding any paratracheal dissection, which is a particular risk in infants with a pliable trachea.

Second, stay as close to the midline as possible, and do not proceed too far inferiorly. In an infant’s short neck, very little room is available for dissection. An infant's pleural spaces extend far superiorly into the neck and can easily be injured during tracheostomy. Postoperative chest radiography is needed to exclude any pneumothorax. Avoiding injury to the cricoid cartilage superiorly is also important.

Third, because of the tube’s short length (especially in infants), displacement of the tube is an important and common problem. A pediatric tracheostomy tube of a given diameter is available in 2 lengths: a longer one for children and a shorter one for infants. Tracheal stay sutures must be placed bilaterally on the incised tracheal wall and taped to the neck with a label saying ”Do not remove.” These sutures can be used to pull the trachea up into the field and facilitate replacement of the tube should it become displaced.

Percutaneous tracheostomy has already replaced surgical tracheostomy in several adult intensive care units (ICUs) and is indeed the procedure of choice in most cases. However, it is rarely done in children, partly because tracheostomy in general is performed less often in children than in adults and partly because of the relative unavailability of appropriate methods or equipment. ^[25] Toursarkissian et al reported performing 11 percutaneous tracheostomies in patients aged 10-20 years without major complications. ^[26]

Fantoni and Ripamonti described a series of translaryngeal tracheostomies (TLTs) performed in very young patients, including some who were only a few months old. ^[27] They found that the TLT mode was intrinsically safe and was perfectly suitable for the anatomy of a child.

In fact, according to the authors, as the procedure is carried out from inside to outside, the tracheal wall tends to evert, and this eversion must be limited with external pressure. This application of pressure and the resulting compression of the peristomal tissues create essential advantages (ie, complete absence of blood loss, minimal local trauma, and perfect adherence of the stoma to the cannula, particularly effective at the level of the tracheal wall) in younger children that cannot be found in other tracheal techniques.

Complications of Tracheostomy

Complications of tracheostomy may be conveniently divided into early, intermediate, and late.

Following an assessment the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) Pediatric that demonstrated that the highest contribution to composite morbidity in otolaryngology is seen in children younger than 2 years undergoing tracheostomy, a study by Mahida et al looked to determine predictive factors for complications following tracheostomy placement in this age group. The study found that of the 206 children younger than 2 years who underwent tracheostomy, 50 (24.3%) experienced a major complication within 30 days. The most common complications were pneumonia (16 [7.8%]), postoperative sepsis (12 [5.8%]), death (12 [5.8%]), and deep or organ space surgical site infections (8 [3.9%]). Neonatal age, intraventricular hemorrhage, and comorbid cardiac risk factors were independently predictive of major complications. ^[28]

Early complications

Pneumomediastinum is a potential early complication. In infants, the apex of the lung extends into the root of the neck. The surgeon must stay in the midline of the neck to prevent violation of the pleural space. ^[11]

Postoperative radiography can be used to exclude a rare pneumothorax, which can result from injury to the lung apex or high-pressure ventilation in neonates. ^[29] It has been argued that postoperative radiography should not be routine but should be reserved for cases in which there are grounds for suspecting a complication. ^[30]

With acute hemorrhage, specific attention should be paid to the thyroid isthmus. Hemorrhage is rarely a complication if the thyroid isthmus is divided with an electrocautery.

Accidental decannulation is a serious complication in children. A false passage anterior to the trachea can easily be formed during emergent reinsertion of the tracheostomy tube. Properly placed stay sutures are the best means of preventing this problem. Early tube dislodgement must be prevented by carefully adjusting the tape and placing stay sutures through the trachea on either side of the tracheal incision. If the tube is dislodged, the sutures can be pulled to either side to open the incision and bring the trachea to the surface.

Conventional adult tracheal dilators are usually too large, but a small curved artery clamp is ideal when a tube needs to be inserted. This item should be at the child’s bedside with 2 spare tracheostomy tubes (of which 1 should be a smaller size). Because shorter tubes are more likely to dislodge, the correct length for age must be selected (see Periprocedural Care).

Tubal obstruction can be prevented with appropriate perioperative tube care. Tube blockage is avoided by providing frequent suctioning and maintaining an awareness of the problem.

Subcutaneous emphysema can be avoided by using a tight-fitting tube in the trachea and making sure that the wound is not closed too tightly.

To avoid hemorrhage, vascular anomalies must be identified preoperatively. When such anomalies are present, tracheostomy should be avoided if possible.

Intermediate complications

Local infection at the tracheostomy site can produce excessive granulations. This can cause difficulty in the changing tube and result in difficult decannulation.

In chronically tracheostomy-dependent children, tracheobronchitis can occur and is typically diagnosed clinically on the basis of fever and recent onset of purulent tracheal secretions in the absence of other causes for these findings. Sputum cultures are helpful in management, but positive cultures alone are insufficient to clinch the diagnosis.

Centers for Disease Control and Prevention (CDC)/National Healthcare Safety Network (NHSN) surveillance definition for ventilator-associated tracheobronchitis (VAT) (both for ETT or tracheostomy assisted), is as follows ^[31] :

●Absence of clinical or radiographic evidence of pneumonia, AND

●A positive culture obtained by deep tracheal aspirate or bronchoscopy, AND

●≥2 of the following signs or symptoms with no other recognized cause:

•Fever >38°C (taken rectally in infants ≤1 year of age)

•Cough

•New or increased sputum production

•Rhonchi and/or wheezing

•And, in infants ≤1 year of age: Respiratory distress, apnea, and/or bradycardia

Late complications

Difficult decannulation is a common late problem. Decannulation problems in children can be due to various factors. The lower respiratory tract must be free of infection and excessive secretions when decannulation is contemplated.

If decannulation fails, microlaryngoscopy and bronchoscopy must be performed to reveal any stomal granulations in the trachea or any large suprastomal tracheal tags obstructing the lumen and to evaluate the mobility of the vocal cords. If any of these problems are present, they must be addressed before the child is decannulated. Psychological dependence on the tube is not as common as is often believed.

Tracheal granuloma frequently occurs in very young patients, in whom the margin of safety mirrors the caliber of the airway. The most common cause is granulation due either to trauma at the distal tip of the tracheostomy tube or to excessive suctioning. This complication probably results from a combination of physical features (eg, movement and the effect of plasticizers in the tube) and infective factors from the skin and airway that contribute to granulation formation.

Accidental decannulation becomes more of a risk as a young child develops the manual dexterity to remove the tracheostomy tube. Tube dislodgment and blockage remain the most important late complications and are associated with a mortality of 1-2%.

Subglottic stenosis is generally caused by inserting the tube too high and too close to the cricoid. Suprastomal collapse and tracheal stenosis (see the videos below) are also important complications. The incidence of suprastomal collapse inversely increases with the age of the child at the time of tracheostomy insertion. An epiglottic repositioning technique for supraglottic stenosis/collapse has been described. ^[32]

The incidence of persistent tracheocutaneous fistula is 19-42%.

Finally, tracheostomy can affect speech and language development, both in patients who have neurologic disorders and in those who do not. Crucial factors that affect speech and language development within the neurologically healthy group include age at the time of tracheostomy and duration of the tracheostomy before decannulation. Performing decannulation as early as possible improves the chances of normal speech and language development. ^{[33, 34]}