Orthotic Management of Congenital Tracheal Stenosis at UCSF: A Twenty-Year ReviewBy Laura Franz Orthotic Resident AbstractCongenital tracheal stenosis, a narrowing of the trachea, is a rare and potentially fatal disorder that presents a challenge to even the most experienced Orthotist. This literature review will discuss the obstruction levels, surgical management, and a history of orthoses used at the Orthotic & Prosthetic Center at University of California, San Francisco over the last twenty years. Congenital tracheal stenosis, a narrowing of the trachea, often with associated cardiopulmonary anomalies, is a rare and potentially fatal disorder that presents a challenge to even the most experienced surgeons and orthotists. Although there is a high mortality rate associated with tracheal stenosis, recent advances in surgery have lead to an increase in survival rate. Surgical options include: dilation, resection, and tracheoplasty. Post-operative care includes initially maintaining paralysis and sedation. Following resection surgery, a custom CTLSO keeping the child's head and neck in a completely flexed position, is a crucial component for a successful resection.
The average length of a newborn trachea is about 4.0cm, or about 1/3 that of an adult. The diameter of a newborn trachea is about 5.5mm (figure 1). In an adult the narrowest portion of the trachea is at the level of the vocal cords, where in the infant it is in the subglottic area, immediately below the vocal cords, and it is here that stenosis is most likely to occur (Hamelink, 1989). It is important to realize there is a difference between tracheal stenosis and tracheomalacia. Tracheomalacia is a weakness of the trachea wall, with a collapse of the lumen during inspiration and opening again during expiration. In tracheal stenosis there is a normal lumen, but narrowing of the trachea itself. There are three types of stenosis commonly recognized: segmental or focal stenosis, funnel-like narrowing, and diffuse stenosis. The majority of stenoses occur at the upper and middle trachea, which often do not require resection (Mansfield, 1980). Segmental stenosis, about 50% of tracheal stenosis cases, is evenly distributed between the subcricoid area, the central trachea, and above the carina. Funnel-like stenosis, or a narrowing over the entire trachea, makes up about 20% of the cases, and a left pulmonary artery sling is commonly associated with this type. Diffuse stenosis, or generalized hypoplasia, makes up the remaining 30% of cases (Landing, 1979). Distal tracheal lesions are difficult to manage and have a higher morbidity and mortality rate than subglottic and high tracheal lesions. Left untreated, stenosis of the distal trachea can lead to lethal airway obstruction (figure 2).
Symptoms of tracheal stenosis include stridor with inspiration, retraction of the chest wall, and prolonged expiration. Manifestation of tracheal stenosis may also present in the form of repeated respiratory infections, barking cough, wheezing, cyanotic attacks, repeated croup, bronchitis, bronchiolitis, near-miss sudden death syndrome, and feeding difficulties. Infants may also hold their heads hyperextended to minimize compression or buckling of the trachea. Symptoms usually are apparent at birth or within one month, but may take as long as several months to become evident. Because the infant's trachea is so narrow any obstruction is significant. For example, "one millimeter of edema in the subglottic region of the normal newborn infant will reduce the airway to 32% of its former area" (Hamelink, 1989). X-ray examination, barium swallow with video recording, xeroradiogrphy of the upper trachea, computed tomographic scan, inspiratory and expiratory flow volume curves, echocardiography, angiography, brochoscopy, and bronchograms are all diagnostic tools in determining if there is a stenosis present (Nakayama, et. al, 1982). However, if the stenosis is severe, time may not allow for an extensive diagnostic workup, and some of these studies may further traumatize the trachea and lead to complete obstruction. For this reason, studies should be performed with much consideration and planning. Indications for operation in one study by Thorm E. Lobe, et. al., in 1987 included: "unrelenting respiratory distress despite maximal nonoperative therapy, ventilatory dependency, multiple admissions for respiratory symptoms including 'reactive airway diseases' and asthma, and failure to thrive." Multiple techniques have been suggested from watching and waiting to intensive respiratory supportive therapy (Lobe, et. al, 1987). According to Nakayama, et. al., "key factors in prognosis are the length of involved trachea and the caliber of the airway proximal and distal to the lesion." There are three prevailing surgical methods for treating tracheal stenosis: dilation, tracheoplasty, and resection. Stenotic area may be visualized on tracheoscopy or bronchoscopy, which then also allows for direct dilation of the stenotic area. Dilation may need to be repeated in cases of narrow stenotic areas, and corticosteroids are often used in dilation procedures (Hamelink, 1989). In tracheoplasty a longitudinal incision in the trachea over the stenotic segment is made a graft is then sutured into the trachea to enlarge the lumen diameter (Hamelink, 1989). Common material for grafting includes: esophagus tissue, pericardial patch, tibial periosteum, costal cartilage, and dura. Tracheal resection is only performed in cases of severe stenosis that cannot be dilated (Hamelink, 1989). Resection may also be performed in cases of funnel or segmental congenital tracheal stenosis and pulmonary artery sling cases with complete tracheal rings (Mansfield, 1980). Resection of the stenotic segment with end-to-end anastamosis is considered standard treatment for short lesion. One-third to one-half of the trachea can be resected safely, with the trachea growing to 80% of its normal length.
In performing a tracheal resection surgery, "the trachea should be transected at the most distal area of narrowing so that a sterile endotracheal tube and connecting tubing can be placed into the distal airway to continue ventilation" (Nakayama, et. al, 1982). In a normal length trachea, the incisions for exposing the trachea are a transverse cervical and median sternotomy. However, in an elongated trachea, or one with irregular bronchial branches, a posterolateral thoractomy on the opposite side of the aorta must be performed. A tracheal tube is then placed in the right or left main bronchus, and the trachea is transected proximally, at various levels, until the widest lumen is identified for anastomosis. When tying off sutures it is imperative the head and neck are flexed to relieve tension on the sutures (Nakayama, et. al, 1982), (Figure 3). Several approaches of resection and reconstruction have been used, all of which have been ineffective. Prosthetic replacements have been unsuccessful "because granulation tissue leads to progressive airway stenosis and infection is always present" (Hamelink, 1989). Other unsuccessful reconstructions included using the patients left bronchus to reconstruct the trachea as well as using a tracheal replacement with an autologous esophagus. Following surgery, close attention to the airway is essential, as well as evaluation of arterial blood gas levels to detect acidosis or respiratory failure. "It is especially important to avoid endotracheal intubation postoperatively and, if necessary only for a short time (Alstrup, 1984). Patients should also be kept quiet and sedated (complete paralysis) to avoid strain on the repair site. When turning a patient, care should be taken to turn the patient as a unit (rotate the head, neck and body at the same time). One of the most important post-operative items is to maintain the head and neck in a flexed position to minimize tension on the surgery site. This position should be maintained for 4-6 weeks (Hamelink, 1989). In performing an extensive literature review, only three articles were found to mention the use of orthoses following tracheal stenosis resection surgery (Harrison, et. al., 1980; Longaker, et. al, 1990; Nakayama, et. al., 1982). However, only Longaker, and Nakayama presented pictures of the children in the orthoses, and no extensive guidelines were given. Orthotist's at the Orthotic & Prosthetic Center at UCSF have had the opportunity over the last twenty years to work with surgeons and fabricate orthoses for children following tracheal reconstruction. The process is challenging every step of the way (Christensen). The first challenge faced by an Orthotist is pre-operative measurement; as only about half of the time does the opportunity arise to see the patient prior to surgery. For this reason, one of the key factors in fabricating an orthosis is to be able to make it in the ICU, if necessary. However, the most important features of the orthosis are elimination of cervical extension and proximal and distal drift, and allowing for easy management of nursing care, especially in the ICU (Harrison, et. al., 1980). The child must also be able to wear the orthosis continuously for at least 4-6 weeks (Nakayama, et. al, 1982). Other key features to keep in mind while fabricating the orthosis is to allow for regular cleaning, avoid skin breakdown from too much pressure applied to the head, and finally to allow maximum function with neck near maximum flexion when the patient becomes mobile.
The first orthosis made at UCSF, in 1980, was a total contact headpiece with extensions running anteriorly and posteriorly down the upper spine (figure 4). The orthosis was worn by a 16-month-old child. It was worn for six weeks with minimal skin breakdown, but was difficult to open and clean. The major problem with the orthosis was the lack of extension control, especially for a child who was beginning to become active, which lead to the conclusion that the next orthosis needed longer distal lever arms.
In 1985, ready to improve on the previous design by providing more extension control, a modified sling design was fabricated, for a four-month-old baby. The orthosis was designed from a plaster impression of the posterior aspect of the patient's head and entire spine. An anterior strap was used to keep the patient cradled in a flexed position. Skin monitoring instructions were given, but within two days a grade III ulcer developed on top of the patient's head, as too much pressure was applied to the area. The anterior strap and superior portion of the headpiece were eliminated and replaced with an extended Philadelphia collar. These changes offered relief to the ulcerated area and unrestricted access to the patient's torso, but the success of these changes compromised some cervical extension control (figure 5, 6), thus increasing the sedation and paralysis time. In 1990, the orthosis used was a modified SOMI orthosis adapted to maintain cervical flexion. This design was used on older patients and required several modifications for holding the head in flexion and controlling proximal and distal migration of the orthosis on these more active children. The orthosis was made of kydex, had a high anterior thoracic pad, to counter the flexion force of the occipital pad, and strapping around torso and legs to limit proximal migration (figure 7). The swivel control of the occipital piece was retained, which was a significant advantage over the first orthosis for control of the head and neck. As this design was difficult to clean while on the patient, two braces were fabricated for each patient. In this way one could be worn and one cleaned, while the patient was kept in a stable position at all times. This design caused a significant amount of fabrication and adjustment time. And due to the lower profile design of the orthosis, the patient's were kept sedated longer. However, since this design was successful, with minimal skin lesions, it was used four more times over the next ten years.
The last orthosis used was in 2001 and was modeled after the Milwaukee brace. It was custom fabricated, as pre-operative measurements and fabrication were possible, for a 5-year-old boy. The orthosis had a molded headpiece lined with sheepskin. The headpiece kept the head in a 30-degree flexed position, stopped extension, and had a split in it so the skin on the head could be reached and cleaned (figure 8). However, too much pressure was concentrated on the occiput and a stage III ulcer developed (figure 9). By using a gel donut relief pad the area was relieved and the ulcer gradually healed. This orthosis was higher profile, fitting for a child this age who needed more control of head flexion once no longer sedated.
The final orthosis fabricated at UCSF, also in 2001, again was custom fabricated pre-operatively, for a two year old child. This orthosis was total contact, thermoplastic, and similar to the Milwaukee model, but was bivalved for easy donning and cleaning, and lined with sheepskin for comfort (figure 10). Due to the success of the surgery, the surgeon did not feel the orthosis was necessary and was not used.
In conclusion, tracheal stenosis is a rare and potentially lethal disorder that may require resection of the narrow portion of the trachea. In treating these patients an experienced surgeon and a creative orthotist with an understanding of biomechanics is required. The Orthotist's at UCSF have learned over the years in taking care of children following tracheal resection surgery that by increasing the length of the lever arms on the CTLSO's an increase in motion control is gained. This helps keep the head and neck in a flexed position and limits extension. The lever arms in the first orthosis were not long enough, and through the use of the other orthoses over the years it was determined that by extending the orthosis to the pelvis cervical extension was best controlled. This design, of extending the orthosis to the pelvis, not only stopped cervical extension, but also prevented migration of the orthosis when supine, sitting, or standing. The control of the different orthoses was also directly related to the age and activity level of the children. The older, more active children required an orthosis that would offer more control the head flexion, thus a higher profile orthosis was needed. It is important to remember that too much control may cause too much skin pressure, resulting in skin breakdown. Although it did cause skin breakdown, the modified Milwaukee, was ultimately the most successful with keeping the child's head in a flexed position, allowing minimal movement of the orthosis, easy skin care, and ease of donning by the family and nursing staff. In the future, improved skin care needs to be addressed while staying focused on the orthotic criteria of taking care of children recovering from tracheal stenosis resection.
Work Cited
I would like to extend a special thank you to James Jackson, RFO who put countless hours of work into fabricating many of the aforementioned orthoses, found old orthoses for pictures, and helped put into perspective the history of orthotic management of congenital tracheal stenosis. |
