Abby Motz, MSc, RRT-NPS, and John Pack, RRT, Cincinnati Children’s Hospital, Cincinnati, OH
Introduction: Airway stenting is becoming a popular intervention for relieving airway obstructions, as well as tracheobronchial malacia and stenosis in the pediatric population. Three types of airway stents are frequently used: silicone, metal, or hybrid (metallic support structures with a silicone body).1,2,3 Airway stents are typically placed under general anesthesia with a rigid bronchoscope, but can also be placed with a flexible bronchoscope with the aid of fluoroscopy.2,3,4 In addition, airway stenting can facilitate airway secretion removal from those areas of the lung(s) in which the stent is located.
Airway clearance techniques can be employed to aid in secretion removal and to improve atelectasis. Common airway clearance devices include: chest physiotherapy (manual or high frequency chest oscillation), cough assist, flutter or acapella therapy, intermittent percussive ventilation, and suctioning. Although evidence regarding efficacy is limited, the choice of which airway clearance device to use for a specific patient or patient population is generally decided based on pertinent clinical signs and symptoms, as well as the degree of purulent mucus plugging. There are very few reports that discuss the need for airway stenting due to vascular compression in combination with aggressive pulmonary clearance techniques in the pediatric population.
Case: This case involves a four-year-old female with trisomy 21 and a history of a right ventricular (RV) dominant unbalanced artrio-ventricular (AV) canal with hypoplastic left ventricle and left pulmonary artery (LPA) hypoplasia who was admitted for elective Fontan palliation (Fig. 1).
She had previously undergone both Norwood and Bidirectional Glenn palliations. At the time of her pre-Fontan catheterization, moderate LPA stenosis was noted. Her LPA was balloon dilated and a stent was placed (1910 Genesis) with angiographic improvement (Fig. 2).
She underwent extracardiac fenestrated Fontan palliation. During her postoperative period, she was hypotensive with signs of severe low cardiac output and high Fontan pressures, so she was taken back to the OR for Fontan takedown. On post-operative day 3, following Fontan takedown, she was successfully weaned from inhaled nitric oxide (iNO) and mechanical ventilation, and was extubated to high-flow nasal cannula (HFNC) at 8 lpm. She was subsequently weaned to a standard nasal cannula (NC), and manual chest physiotherapy (CPT) was order to augment secretion removal.
On post-operative day 8, she required reintubation and mechanical ventilation, and was placed on iNO due to progressive respiratory distress and worsening arterial blood gases and chest x-ray. Bedside flexible bronchoscopy revealed severe compression of her left main stem bronchus (LMSB), rendering her left lung essentially nonfunctional (Fig.3).
Fluoroscopic assessment during catheterization demonstrated the left lung was hyperinflated with minimal left diaphragm movement, demonstrating poor left lung ventilation due to air trapping in the left lung. The left lung hyperinflation also resulted in decreased blood flow to the left lung due to increased left lung airway pressures. This observation explained her failed Fontan palliation because she was essentially a single lung Fontan palliation. The patient underwent both rigid and flexible bronchoscopies in which a 6 x 19 mm silastic stent (Hood) was placed in her LMSB from just below the carina and extending distally, bridging the area of the collapsed airway.
On post-operative day 11, a bedside bronchoscopy revealed that the silastic stent was migrating proximally and causing circumferential necrosis of the mucosa of the LMSB (Fig.4).
Subsequently, the stent was removed via a rigid bronchoscopy. Her positive end expiratory pressure (PEEP) was increased from 5 cmH2O to 10 cmH2O and aggressive bag ventilation, suction, and saline lavage were performed in an effort to maintain left lung patency. Over the next 18 days, the patient received 12 bedside bronchoscopies to treat persistent atelectasis, mucus plugging, and bronchial compression. During this time frame, she remained on high ventilation settings with iNO administration and required frequent bag-ventilation, suction, CPT, and lavage to facilitate secretion removal and to maintain adequate oxygenation and ventilation.
Due to the need for aggressive pulmonary clearance resulting from severe LMSB compression, the medical team opted to replace the bronchial stent rather than remove the left lung. Over the next eight days, the patient was transitioned to vest CPT, successfully weaned from mechanical ventilation, and extubated to 8 lpm HFNC with iNO.
Over the next two days, she became febrile, with increased work-of-breathing and apneic episodes. She was placed on full-face BiPAP with 100% oxygen and iNO. The patient continued to decompensate with poor oxygenation and was emergently reintubated and placed on mechanical ventilation. Shortly after reintubation, another bedside bronchoscopy was performed for lung recruitment and to evaluate the location of the LMSB stent, which was confirmed to be in good position with minimal compression.
Two days later, the patient had a cuffed pediatric Arcadia tracheostomy tube placed. Six days after receiving her tracheostomy tube, the patient was weaned off iNO and manual CPT was re-initiated. She successfully transitioned to cool mist trials during the day via trach collar, vest CPT, and BiPAP ventilation while sleeping. She was transferred from the ICU to the transitional care unit and was successfully discharged home.
Discussion: Airway stents are being used with increasing frequency for bronchial compression in the pediatric population. Vascular compression of the airways is among the most common causes of pediatric bronchial compression, especially in patients with congenital heart defects that involve the great vessels.5 Ferandos et al. reported 23% of the patients who required airway stents for bronchial compression had adjacent vascular stents.6 Additional studies have produced the same findings in regards to complications from the use of stents in the pulmonary arteries.7,8 In the current case, placement of the LPA stent inadvertently resulted in LMSB compression that was associated with severe hyperinflation of the left lung, which caused decreased mobility of the left hemi-diaphragm and decreased ventilation and perfusion of the left lung.
Mucus plugging and atelectasis are secondary complications associated with airway compression. In our patient’s case, she developed severe mucus plugging, and essentially her entire left lung became atelectatic. The use of airway stents was an option we chose over a possible lungectomy. Our patient had two different airway stents placed due to complications associated with her silastic stent. The most common complications associated with airway stent placement are the formation of granulation tissue, fracture, and stent migration.4,9 Our patient’s Hood stent caused significant granulation tissue as well as periodic migration into her right main stem bronchus; thus the removal of her stent.
Because her mucus plugging was so severe, almost daily bronchoscopies were needed to remove her secretions. Because of the accessibility and the relative ease of use, flexible bronchoscopy should be considered an option for aggressive secretion removal.10 Complications from flexible bronchoscopy are rare, but include transient hypoxemia and hypercarbia, as well as increased peak inspiratory pressures and low minute volumes if the patient is receiving mechanical ventilation.
Less invasive airway clearance options should be considered to relieve mucus plugging and atelectasis in addition to bronchoscopy. Manual CPT, vest CPT, bag (manual ventilation with PEEP), suction, and lavage are all done at the patient’s bedside with relative ease.11 Hemodynamics should be closely monitored during these procedures to ensure that the patient does not have any adverse effects like decreased HR, oxygen saturations, and blood pressure. Our patient tolerated these additional procedures without any side effects.
In closing, with severe extrinsic compression of the LMSB, airway stenting should be considered a treatment option in addition to aggressive pulmonary airway clearance.
Susan Butler, BS, RRT-NPS, CPHQ, Children’s Hospital of Philadelphia, Philadelphia, PA
The anatomy of the pediatric and neonatal airway differs significantly from that of the adult. Smaller airway structures and resistance factors put these patients at high risk for adverse events associated with intubation and airway management. As part of an organizational safety initiative and quality improvement process at the Children’s Hospital of Philadelphia, an airway management and escalation pathway standard was developed to address possible anticipated and unanticipated adverse safety events associated with placement of an endotracheal or tracheostomy tube in these patients.
Creating a situational awareness to reduce emergencies was the first step in the process. The group focused on the “at risk” patient, targeting early identification, a shared definitional framework, and implications for management plans and patient placement. Standardized operational definitions were enlisted through peer-reviewed journal and multi-departmental evaluation. These, most importantly, included airway and patient characteristics of the at risk populations.
Difficult Airway was defined as any patient who:
Critical Airway was defined as any patient who:
An algorithm for identification of the unanticipated difficult airway patient was adopted organizationally to be used as a guide during intubation. The algorithm contains a clear, consistent pathway to intubation, provides guidance for early recognition of intubation failure, and includes a decision tree for system activation and airway maintenance. Use of this failure index promoted an early interruption of additional failed attempts.
To further increase system reliability, the team created an orchestrated response system that includes uniform equipment, availability of skilled personnel, pre-defined roles and responsibilities, full time team coverage, standard clinical approaches, and a quality review system.
The team formalized a standardized, reliable, layered communication system, including an electronic activation similar to code calls and rapid response team notification. All devices are carried 24/7. The system is tested for notification verification weekly with a test call/page requiring response.
Another key concept was standardizing the Difficult Airway Carts such that if the Airway Response Team is called to any of the critical areas, there will be no problems finding equipment necessary for airway securement. Carts employ human factors engineering concepts common in other emergency response or “code” carts. For the most part, the carts already contained most of the equipment. For maximum patient safety, it was recommended that various sized bronchoscopes also be included.
The committee made recommendations to ensure adequate documentation in the electronic health record (EHR), with visual cues and a record of the problem in several places. Bedside signs were developed to call attention to patients at risk and to document a solution to securing the airway in an emergency.
Critical and Difficult Airway Signs: Color coding was used to aid in rapid visual discrimination between the two types of scenarios. The reverse side of the signs were printed with the airway features’ qualifying operational definitions.
The signs are located outside patient rooms (HIPAA compliant) and at the head of the patients’ beds. The signs inside the rooms are inscribed with patient identifiers, anomalous airway features, and the method last used to successfully place the airway (with tools and approach used, type of airway, and additional information needed to replace and re-secure a dislodged airway).
Education was provided by unit and departmental representatives as each phase of the process went live. Screensavers with key points were deployed throughout the clinical areas and an interactive learning module was created and assigned to a broad clinical audience.
During implementation, a quality improvement team collected a data tool completed by the charge respiratory therapist, who is an integral part of the emergency response team. The form gathered objective and subjective data regarding response time, team dynamics, equipment employed during the emergency, and patient disposition.
The quality improvement team conducted rounds on known difficult and critical airway patients for accuracy in signage and EMR flags for emergency information. Just-in-time feedback was given to the bedside team for any deficiencies. Providers were contacted to provide reminders or to gather more information when gaps in documentation were found. This helped to support education provided during implementation.
The NEAR-4-Kids intubation registry provided intubation statistics, as well as data for individual intubation events.
Safety promotion and quality improvement science contributed to the development, promotion, and acceptance of the process. A determined organizational focus to prevent harm, provide high reliability care, and improve outcomes helped engage departments and practitioners in the context of our organizational improvement framework.
Early lessons from implementation included limitations of the practitioner notification process and in physician coverage. Anesthesia increased their hospital presence and otorhinolaryngology backup support was expanded.
Next steps include further automation of EMR reporting for data collection and analysis.
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