Assessment Considerations for PMV® Candidacy in the Pediatric Population
Jessica Shaw, MS, CCC-SLP
Premature birth is defined as birth before 37 weeks gestation and is the leading cause of death in babies in the United States. According to the March of Dimes, for the first time in eight years, the preterm birth rate in United States has increased to 9.63% as reported by the National Center for Health Statistics (NCHS) (2016 Premature Birth Report Card, 2016). These premature infants often face health issues such as respiratory complications, jaundice, retinopathy of prematurity, developmental delays, and gastrointestinal complications, among others. The National Academy of Medicine reports that preterm birth costs $26 billion dollars annually. Due to advances in medical technology and scientific innovation, more micro-preemies, those born at less than 26 weeks gestation or less than 800g, and those with congenital abnormalities are surviving, but not without frequently facing prolonged medical challenges.
Due to the underdevelopment of the respiratory system and risk for development of Bronchopulmonary Dysplasia (BPD), respiratory support via mechanical ventilation is imperative for children who survive early birth. Bronchopulmonary Dysplasia is a form of chronic lung disease that can develop in preterm infants who have been treated with oxygen or positive pressure ventilation. Symptoms of BPD include tachypnea (increased respiratory rate), tachycardia (increased heart rate), frequent desaturations, and increased respiratory effort. Increased respiratory effort may be evidenced by any of the following: retractions, grunting, or nasal flaring. This is despite the introduction of surfactant therapy and increased use of noninvasive positive pressure ventilation (Overman, et al., 2013). Many of these infants will require tracheostomy placement due to the need for prolonged mechanical ventilation or the presence of upper airway abnormalities which prohibit successful extubation. Supportive research has stated that early tracheostomy has reduced the occurrence of associated subglottic and tracheal stenosis for children who have had prolonged intubation (Overman, et al., 2013).
Impact of a Tracheostomy
Tracheostomy is the outcome of the tracheotomy procedure that creates an artificial airway in the trachea and redirects airflow, bypassing the patient’s upper airway. This procedure is performed by a pediatric surgeon or otolaryngologist. One method for this procedure is to have a vertical or horizontal incision made below the level of the vocal folds over the 3rd-4th cartilage ring (Alladi, et al., 2004), creating a stoma wherein a tracheostomy tube is placed to create the artificial airway. Indications for tracheostomy placement include the need for long-term mechanical ventilation, upper airway obstruction, poor pulmonary hygiene, and poor secretion management (Abraham, 2003). When looking at the reasons for tracheostomy in 184 infants, 78.8% of those born at extremely low birth weight had more than one reason for tracheostomy placement, including diagnoses such as bronchopulmonary dysplasia, congenital heart defect, subglottic stenosis, respiratory failure, and laryngeal ortracheomalacia (Overman, et al., 2013). While tracheostomy placement is often lifesaving, the placement of tracheostomy is not without secondary complications.
Documented complications of tracheostomy placement include tracheal infections, accidental decannulation, obstruction, reduced or absent airway protection, reduced secretion management, swallowing deficits, and reduced ability to produce voice (Abraham, 2003). In children who undergo tracheostomy prior to the development of speech during infancy or early childhood, the development of oral communication and verbal interaction with their environment may be delayed. Use of a Passy Muir® Tracheostomy and Ventilator Speaking and Swallowing Valve (PMV®) can aid in the ability to restore airflow through the upper airway, which would allow a child to produce a cry or voicing and normalize aspects of language development.
Additionally, the use of the PMV has been documented to improve secretion management, aid in weaning of respiratory support, and improve airway protection responses in both adults and children due to the restoration of upper airway sensation (Sutt et al., 2015; Blumenfeld et al., 2011). It has been stated that use of PMV in appropriate candidates less than two years of age has resulted in more normal acquisition of vocal exploration and speech development (Engleman & Turnage-Carrier, 1997; Jiang & Morrison, 2003). Considering the positive outcome with PMV use, clinicians working with the pediatric population with tracheostomies should aim to establish PMV use as soon as medically and clinically appropriate.
Assessment For Passy Muir® Valve Use In Children
Assessment for PMV use in children can create additional challenges for the clinician when compared to evaluation for use in adults. Children, specifically infants and those under the age of two years or those with developmental delays, are not able to voice on command which would typically be a method used with older children or adults during assessment of upper airway patency. When initially assessing with digital occlusion, voicing or attempting to voice is generally used to look for an ability to pass air around the tracheostomy tube and up through the vocal cords. Very young children also cannot articulate feelings of discomfort during PMV trials. Furthermore, in young children who have had a tracheostomy for the majority of their life, they may not be able to complete a more normalized exhalation process and may not be able to coordinate exhalation with phonation. Because volitional voicing may not be possible with infants and young children, other considerations must be used during assessment and treatment. A clinician may have to target this coordination with therapeutic interventions until true voicing can be heard. This is different when compared to an older child or an adult patient with a tracheostomy who has had prior experience of vocalizing and speaking without the presence of the artificial airway.
Clinical assessment considerations
When moving toward assessment of the nonverbal or young child, the first step is to complete a thorough review of their medical history and discuss it with the child’s medical team to rule out any contraindications for PMV use. Contraindications for PMV use may include severe subglottic stenosis, severe tracheomalacia, tracheal edema, bilateral vocal fold paralysis in the adducted position, severely reduced lung compliance, or the presence of an inflated cuff or foam-filled cuff tracheostomy tube. Due to the small size of the pediatric trachea, there is a greater risk of airway obstruction. The airway diameter in infants less than six months of age is approximately 4 mm and grows to 8-11 mm by the time a child is approximately 10 years of age. Considering this small tracheal size, even slight congenital or inflammatory obstruction can lead to increased risk of airway obstruction (Alladi, et al., 2004). Therefore, the proper sizing of the diameter of the tracheostomy tube in relation to the size of the child’s airway is crucial to adequate airflow through the upper airway and for successful usage of a PMV.
In the pediatric population, both pediatric and neonatal tracheostomy tubes may be used. The difference between the two is length, with the pediatric tube being longer than the neonatal tube but the inner diameter remaining the same. It is the inner diameter of the tracheostomy tube that is often described when the question is asked, “what size tracheostomy tube do they have?” Throughout the time that a child may remain tracheostomized, the size and length of the tracheostomy tube requires modification to accommodate changes in airway due to growth or respiratory support needs. A pediatric otolaryngologist can assess the airway and tracheostomy by direct laryngoscopy to determine appropriate size and length. Because of these potential changes, the clinician must continually monitor and evaluate the needs of the child.
Another variable to consider that affects the tracheostomy and potential obstruction in a child’s trachea is the presence or absence of a cuff. Placement of the PMV requires full deflation of the cuff, yet having the added circumference of the deflated cuff material present can reduce airflow and affect the ability to use the Valve. When working as part of an interdisciplinary team, it is beneficial to attempt to transition a child to a cuffless trach as soon as medically appropriate, to reduce its impact on the child’s transition to Valve use.
Airway Assessment: Digital Occlusion
Successful use of the PMV is directly related to the amount of air that will flow around the tracheostomy tube and up through the larynx, nose, and mouth. Variables affecting this airflow include tracheostomy tube size in relation to patient’s tracheal diameter, as well as the presence or absence of any anatomical or structural narrowing (i.e. subglottic stenosis). One way that assessment of airway patency can be completed is via bronchoscopy; however, this is an invasive procedure that is unable to be conducted in a wide variety of environments and involves many disciplines (Utrarachkij, et al., 2005).
Current standard practice for bedside evaluation of PMV candidacy in pediatrics is to assess upper airway patency via digital occlusion of the tracheal hub. The clinician occludes the hub by lightly placing a gloved fingertip over the end of the trach tube hub. After digital occlusion and with close clinical monitoring, the clinician then waits to hear voicing or listens for upper airway breath sound, via stethoscope, or by assessing for airflow out through the nose and mouth (e.g. use of a mirror under the nose to look for fogging). While these assessment measures will demonstrate a clinical measure of airflow, it does not give information to the clinician regarding the amount of exhaled air that is moving up and out through the mouth and nose. Use of spirometry has been documented as an objective measure of upper airway patency; however, the use of spirometry continues to depend on the child’s ability to follow commands and coordinate breathing into the spirometer, which can be difficult for some younger or developmentally disabled patients (Utrarachkij, et al., 2005). The added medical complexity and cognitive limitations of this younger population may make identification of successful and unsuccessful PMV trials difficult to distinguish from each other.
Prior to placement of the PMV, the clinician should note the baseline measurements for the infant or child. These would include heart rate, respiratory rate, and oxygen saturations. The clinician also should acquire a good indication of skin color and respiratory pattern through observation. Once baseline measurements are obtained, one indicator of successful PMV use is with observed adequate voicing. With an infant or young child this may include crying, cooing, babbling, or any other vocalizations. Moreover, the child should be comfortable, without changes in respiratory pattern or increased respiratory effort.
During this time, the clinician should not only be monitoring for impact on respiratory function but should be observing the overall state of the child and monitor for changes in physiological or autonomic indicators such as heart rate, oxygen saturation, and respiratory rate. Furthermore, clinical observations should be taken in relation to the child’s coloring, looking for signs of perioral cyanosis and other indicators of decompensation (becoming flushed, sweating, etc.).
Utilization of the PMV is often seen as the first step towards removal of the tracheostomy in a patient who is deemed a candidate for eventual decannulation by their medical team. When a patient achieves wearing the PMV for all waking hours and is on a weaning protocol, the next step is capping of the tracheostomy tube. During capping trials, a solid cover is placed on the tracheostomy hub which completely closes off the tracheostomy and normalizes the use of patient’s upper airway. As part of the medical team, the clinician will assess tolerance of tracheostomy by capping, utilizing a similar protocol as for the PMV assessment. Once a patient is wearing a cap during all waking hours, the patient may then be referred to their otolaryngologist or pulmonologist for consideration for decannulation. In some facilities, this may involve repeat bronchoscopy or an overnight sleep study to assess respiratory readiness for decannulation.
Airway Assessment: Transtracheal Pressure Measurement
As we move towards more objective and data driven clinical practice, the question is asked: how can we more instrumentally and objectively assess the status of a child’s upper airway when they are non-verbal at the time of evaluation? There is documentation in the literature to support the use of end expiratory pressure (EEP) or transtracheal pressure (TTP) during passive exhalation to non-invasively assess upper airway patency as part of the assessment procedures in the pediatric patient for PMV use (Utrarachkij, et al., 2005). This is accomplished using a manometer attached to the PMV via connection tubing and a Washington Tee adapter, or similar adapter that is then placed onto the tracheal hub. The manometer provides a reading of pressure at the level of the tracheostomy at the end of the exhalation. Research has shown a positive relationship between children who demonstrate a clinical inability to wear the PMV as judged by change in heart rate, oxygen saturation, report of respiratory difficulties (chest tightness or coughing), or abnormal breathing patterns during a five minute PMV trial and higher TTP measurements of greater than 10 cmH2O (Utrarachkij, et al., 2005). Furthermore, TTP of < 6 cmH2O was associated with observed clinical tolerance and easier transition of children to PMV wearing schedules (Buckland, et al. 2012; Abraham, 1997, 1995). Research has shown that TTP up to 10 cmH2O is consistent with successful PMV wearing (Buckland, et al., 2012). It is important to note that these TTP measures are to be completed during passive exhalation, such as resting breaths; coughing and other more forceful exhalations will result in increased numbers in TTP and will skew the readings. These measurements also must be taken when a child is calm and quiet, as play and other activities may increase the numbers. Therefore, when air is purposefully expelled with increased force in order to produce voice, in an attempt to clear the airway, or increased due to play or other activities, the manometer pressure reading is not accurate.
An additional factor in PMV usage in children is a behavioral response to the placement of the PMV during assessment and ongoing trials. Children who have undergone tracheotomy at a very early age are often hypersensitive to the feeling of upper airflow through their nose and mouth. For infants and many young children, this may be something that they have not experienced in their lifetime. Due to this lack of experience, children may demonstrate various clinical presentations that appear as respiratory difficulties but require behavioral adjustments. A child may exhibit blowing off the PMV or breath holding, which otherwise may be interpreted as clinical intolerance. The difficulty a clinician faces is determining if these observed symptoms are behavioral or due to reduced upper airway patency or airflow. The presentation of the two may look very similar to the naked eye of the clinician. Monitoring TTP can help determine the etiology of the observed behaviors; whereas, if the TTP is < 6 cmH2O then research has shown it is less likely that the clinical presentation is due to a structural or anatomical issue. If it is determined to be behavioral in nature, clinicians working with a pediatric population should engage the child in some desensitization and use distraction or play therapy during PMV trials. Often with young children, the clinician will institute these techniques prior to the initial assessment in order to set the child up for success. By doing so, the clinician may elicit a period of time that a child can demonstrate passive exhalations while wearing the PMV by helping the child become more comfortable and relaxed during the assessment. As previously discussed, transtracheal pressures are most accurately and reliably measured during passive exhalation. By achieving adequate and accurate TTP measurements, the clinician will have a better clinical assessment for use of the PMV.
If a child demonstrates elevated TTP, further assessment completed by a physician and the clinical team to evaluate airway management may assist with improving upper airway patency and use of the PMV. Elevated TTP, in conjunction with laryngoscopy demonstrating poor tracheal lumen fit (tracheostomy tube size within the diameter of the trachea), provides sufficient clinical information to support the need for a change in tracheostomy tube size. Changing the tracheostomy tube size may allow for improved upper airflow in those children without identified structural or anatomical etiology. Reducing the outer diameter of the tracheostomy tube and increasing the space in the tracheal lumen can improve airflow through the upper airway. This, in turn, can improve use of the PMV and improve clinical tolerance for wearing the Valve secondary to the increased room surrounding the cannula for airflow to move around the tracheostomy tube and into the upper airway.
After assessment of the pediatric patient is completed, if a child demonstrates clinical tolerance of the Valve as evidenced by all physiologic parameters remaining stable and TTP pressure of no greater than 10 cm H2O during passive exhalations, the patient should be started on a wearing schedule based on their behavioral tolerance. This wearing schedule should be advanced until the child reaches the goal of wearing their PMV during all waking hours. During the advancement of the PMV schedule, these children are participating in speech and language therapy with the clinician. Goals of therapy are often focused on advancing language skills, improving functional vocalizations, or cognitive therapy, based on the child’s current and premorbid functioning. Additionally, while research has mixed data on the effects of reducing laryngeal penetration or aspiration in children with tracheostomies (Ongkasuwan, et al., 2014), due to the restoration of upper airflow and improved airway protection via improved cough that is linked to PMV placement (Suiter, et al., 2003), clinicians may consider addressing PMV placement prior to initiating therapeutic feeding goals.
If initial assessment does not indicate that a child is a candidate for Valve use at the time of evaluation, the reason for the difficulty should be considered. If it is due to change in any physiologic parameters previously mentioned or the TTP is consistently above 10 cmH2O, then the medical team must further assess the options. Another consideration is to monitor for increasing TTP with each exhalation. Changes in physiologic parameters or TTP being high may involve a referral to a pediatric otolaryngologist to assess the airway for any signs of stenosis or narrowing and for consideration for reduction in the size of the tracheostomy tube.
Pediatric tracheostomy placement is occurring with greater incidence due to the advancements in medical interventions and the increased survival rate of infants who are premature and those with congenital abnormalities. Long term tracheostomy placement has been associated with delayed acquisition of language and social development (Cowell, et al., 2013). Additionally, long term tracheostomy can impact parent-child bonding and the ability of the child’s family to know their wants and needs due to the communication impairment (Lieu, et al., 1999). Assessment and usage of PMV is important for the normalization and development of the social and language development of these children and can be seen as a first step towards decannulation. Due to the limited volitional participation of infants and young children, the clinical assessment of pediatric use of the PMV presents with specific challenges that are unlike those observed in the adult population. Airway patency is directly related to the successful wearing of a PMV but is difficult to assess objectively through clinical judgement alone. The use of transtracheal pressure monitoring through manometry is a great asset to the evaluation for PMV use in the pediatric population.
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