Abstract
Background:
The RAM cannula® consists of nasal prongs that can be used to administer oxygen, continuous, and bilevel positive airway pressure therapies. Studies have reported the efficacy and utility of the RAM cannula in inpatients requiring noninvasive ventilation (NIV); however, there is limited literature on the use of the RAM cannula to provide NIV in the outpatient setting.
Objectives:
This study aimed to describe the clinical features and outcomes of children who used NIV via RAM cannula in the outpatient setting.
Design:
Retrospective review.
Methods:
We conducted a retrospective review of children treated with outpatient NIV via RAM cannula at our institution between January 2010 and March 2023. The analyzed data included age, diagnoses, indications for NIV, duration of RAM cannula use, complications, and outcomes at 6 months.
Results:
We identified 20 patients who used outpatient NIV via RAM cannula during the study period. The median age at initiation of NIV via RAM cannula was 5.8 months (IQR 2.4-9.9 months). Indications for NIV included sleep-related hypoventilation (15%), restrictive lung disease (25%), obstructive sleep apnea (45%), and chronic respiratory failure (50%), with 6 patients having ⩾2 indications for NIV. RAM cannula was utilized for inability to tolerate conventional NIV interfaces (80%), to alleviate dyspnea (60%), and to avoid tracheostomy (55%). Patients used NIV via RAM cannula for a median duration of 7.7 months (IQR 3.7-20.6 months). Patient outcomes included ongoing usage of RAM cannula (55%), changing to conventional NIV interfaces (15%) or oxygen (10%), weaning off respiratory support (5%), and death (15%). There were no complications related to using the RAM cannula.
Conclusion:
Our study demonstrates the utility of outpatient NIV via RAM cannula in children with a variety of diagnoses until clinical improvement or tolerance of conventional interfaces, and for avoidance of tracheostomy.
Introduction
Noninvasive ventilation (NIV) is being increasingly utilized in infants and children for the management of sleep-disordered breathing and respiratory failure.1-3 Modalities of NIV such as high-flow nasal cannula, continuous positive airway pressure (CPAP), and bilevel positive airway pressure (BPAP) are often used in the inpatient setting to provide respiratory support following extubation, or to avoid intubation during acute illnesses.2,4 In the inpatient setting, NIV is often used in the pediatric, neonatal, and cardiac intensive care units (ICU) for the management of acute respiratory failure. In neonatal ICUs, NIV is widely utilized for the respiratory management of preterm infants with respiratory distress syndrome and bronchopulmonary dysplasia (BPD).5,6 Additionally, NIV is being increasingly used in infants and children for the outpatient management of sleep-disordered breathing, respiratory control disorders, neuromuscular diseases, and chronic respiratory failure.1-3,7,8 The interfaces used for outpatient NIV include nasal, oro-nasal, nasal pillows, and total face masks. Despite the availability of several interfaces to provide CPAP and BPAP therapy to children, outpatient use of NIV is challenging due to limited interface sizes, poor interface fit, and lack of cooperation of the child.1-3 Risks of outpatient NIV with conventional interfaces include skin ulceration, aspiration with full-face masks, and midface hypoplasia.1,2
The RAM cannula consists of soft and flexible nasal prongs to administer supplemental oxygen and NIV in infants and children.5,6,9,10 In a lung simulator model, an appropriately sized RAM cannula resulted in transmission of 60% to 70% of the ventilator set inspiratory and expiratory pressures. 6 In contrast to short binasal prongs, a popular interface to deliver nasal CPAP in infants in the neonatal ICU, the risk for nasal trauma was lower with the RAM cannula. 5 Since the RAM cannula covers a smaller area of the face in contrast to conventional NIV masks, it could be better tolerated in infants and children requiring NIV.10,11 Although the RAM cannula has been used in the inpatient setting and ICUs, there is limited literature regarding the safety, efficacy, and long-term outcomes of children using the RAM cannula for outpatient NIV.4,10,11 At our institution, the RAM cannula has been utilized for outpatient NIV in children with sleep-disordered breathing, chronic respiratory failure, and genetic conditions when conventional NIV interfaces were not tolerated either due to limited patient cooperation, lack of well-fitting interfaces (such as with craniofacial and genetic disorders), and for patients seeking comfort-based care without invasive ventilation via tracheostomy. Based on our experience with using the RAM cannula for outpatient NIV, we hypothesized that NIV via the RAM cannula can be used in the outpatient management of infants and young children. The aims of our study were to describe the clinical features and outcomes of infants and children who used outpatient NIV via the RAM cannula.
Methods
We conducted a retrospective study of children aged 0 to 18 years who utilized the RAM cannula® (Neotech, Valencia, California, USA) for NIV at our hospital between January 2010 and March 2023. The Institutional Review Board at Children’s Healthcare of Atlanta approved the study. In this study, NIV was defined as the administration of CPAP or BPAP using various interfaces. Patients were identified by reviewing the medical records of patients who received NIV in-hospital and in the outpatient pulmonology and sleep medicine clinics at Children’s Healthcare of Atlanta during the study period. Patients were included if they used the RAM cannula for NIV in the outpatient setting. Patients were excluded if they only used the RAM cannula in the inpatient setting or if they used other interfaces for NIV in the outpatient setting. Deidentified demographic and clinical data were collected for eligible patients during the study period. The data recorded and analyzed included age, diagnoses, indications for NIV, polysomnography results, duration of NIV use via RAM cannula, ventilator settings, complications, and outcomes. In this study, patient diagnoses were obtained by reviewing the medical records. In patients with restrictive lung disease, the diagnosis was based on clinical data and pulmonary function tests were not performed. Patient outcomes were analyzed for 6 months following the initiation of NIV via the RAM cannula.
At our institution, for patients pursuing outpatient NIV via the RAM cannula, the respiratory therapist fitted an appropriately sized RAM cannula. The RAM cannula is available in 7 sizes based on the nasal prongs septal space and outer diameter. 12 CPAP and BPAP settings were programmed by the physician treating the patient and included titration of settings based on oxygen saturations, capillary/venous blood gas results, work of breathing, or recent polysomnography results. The goals of titrating NIV settings were to optimize oxygenation, ventilation, patient comfort, and to reduce work of breathing. Patients received outpatient multidisciplinary care in the pediatric pulmonology and sleep medicine clinics staffed by a pediatric pulmonologist, pediatric sleep physician, sleep psychologist, respiratory therapist, nurse coordinator, and social worker. Patients were seen every 2 to 3 months in the outpatient clinic. Outpatient evaluations such as overnight pulse oximetry recordings, capillary/venous blood gas tests, and capnography were performed at the discretion of the physician treating the patient. Descriptive statistics (median, interquartile range (IQR), counts, and percentages) were used for analysis and reporting of results. Sample size calculation and power analysis were not performed since we retrospectively reviewed all outpatients who used NIV via the RAM cannula during the study period.
Results
We identified 20 patients who used outpatient NIV via the RAM cannula during the study period. Among patients using outpatient NIV via the RAM cannula, 18 (90%) patients started using NIV in the inpatient setting and were subsequently discharged home on NIV. Two patients started using NIV via the RAM cannula in the outpatient clinic. The median age and weight at the initiation of NIV via the RAM cannula was 5.8 months (IQR 2.4-9.9 months) and 5.0 kg (IQR 4.2-6.7 kg), respectively (Table 1). Patients using NIV had underlying diagnoses such as genetic disorders (65%; like Trisomy 18 and Trisomy 21), restrictive lung diseases (RLD, 25%), and BPD (20%). Most patients used NIV for chronic hypercapnic respiratory failure (50%). Other indications for NIV were obstructive sleep apnea (OSA, 45%), RLD (25%), and sleep-related hypoventilation (15%). Thirteen patients underwent diagnostic polysomnography before initiation of NIV or during the study period at a median age of 9.9 months (IQR 2.4-15.9 months). Polysomnography showed OSA (92%), central sleep apnea (8%), sleep-related hypoxemia (46%), and sleep-related hypoventilation (54%).
Clinical characteristics of the study population, n = 20.
Abbreviations: AHI, apnea-hypopnea index; IQR, interquartile range; NIV, noninvasive ventilation.
Genetic disorders included Trisomy 18 (n = 6), Trisomy 21 (n = 2), Prader-Willi syndrome (n = 1), partial trisomy 2q (n = 1), Crouzon syndrome (n = 1), and osteogenesis imperfecta (n = 2). Restrictive lung diseases included prune belly syndrome (n = 1), osteogenesis imperfecta (n = 2), arthrogryposis (n = 1), and thoracic insufficiency (n = 1). Two patients had Trisomy 21 and bronchopulmonary dysplasia. Two patients had osteogenesis imperfecta and restrictive lung disease.
Six patients had more than 1 indication for NIV use.
The most common indication for utilizing the RAM cannula for NIV was intolerance of conventional NIV interfaces (80%) (Table 2). Other indications for using the RAM cannula were to alleviate dyspnea (60%) and to avoid tracheostomy (55%) based on parental preference or due to redirection of care to comfort-based care (n = 2, 10%). Patients used the RAM cannula for a median duration of 7.7 months (IQR 3.7-20.6 months). Most patients used NIV via the RAM cannula for 24 hours per day (55%), while others used it only during sleep (25%), during sleep and some daytime use (15%), or during the daytime only (5%). NIV was used in CPAP or BPAP spontaneous timed (ST) modes. The Trilogy ventilator (Phillips Respironics, USA) was used to deliver CPAP or BPAP via the RAM cannula. Among patients using CPAP (n = 7), the median CPAP pressure was 8 cm H2O (7.5-9.5 cm H2O). Among patients using BPAP ST mode, the median inspiratory positive airway pressure (IPAP), expiratory positive airway pressure (EPAP), and back-up respiratory rates were 24 (15-30) cm H2O, 10 (8-10) cm H2O, and 22 (20-30) breaths per minute, respectively. None of the patients underwent polysomnography for titration of NIV settings via the RAM cannula.
Respiratory support and outcomes, n = 20.
Abbreviations: BPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; EPAP, expiratory positive airway pressure; IPAP, inspiratory positive airway pressure; IQR, interquartile range; PAP, positive airway pressure.
Two patients utilized both CPAP and BPAP modes using CPAP during the day and BPAP at night.
Patient outcomes were analyzed for 6 months following the initiation of NIV via the RAM cannula. Eleven (55%) patients continued using NIV via the RAM cannula. Three (15%) patients had discontinued using the RAM cannula and used conventional NIV masks due to increased respiratory support requirements. Due to clinical improvement, 2 patients were weaned off NIV and transitioned to supplemental oxygen via nasal cannula, and 1 patient was weaned off respiratory support. There were no complications such as skin ulceration, nasal injury, or aspiration related to using the RAM cannula for NIV. There were no unexpected deaths during the study period. However, there were 3 (15%) deaths due to progression of underlying disease related to Trisomy 18. Among the 3 deaths, 2 patients died in the outpatient setting and received home hospice care. One death occurred due to multiorgan failure leading to redirection of care to comfort-based care.
We identified 6 patients who started using NIV via the RAM cannula in the inpatient setting with the intention for subsequent outpatient use (Table 3). However, these patients were not discharged home on NIV via RAM cannula and were transitioned to conventional NIV interfaces (n = 2) or underwent tracheostomy (n = 4) due to inability to achieve optimal oxygenation and ventilation with the RAM cannula despite increasing the ventilator settings. Therefore, these patients were excluded from our analysis.
Clinical characteristics of patients who used NIV via RAM cannula inpatient but could not be discharged home on the RAM cannula, n = 6.
Abbreviations: IQR, interquartile range; PAP, positive airway pressure.
Discussion
This study evaluated the clinical features and outcomes of 20 children who used outpatient NIV via the RAM cannula. We found that outpatient NIV via the RAM cannula can be used in infants and children with a variety of diagnoses to avoid tracheostomy, to improve gas exchange, and to alleviate dyspnea. Most patients started using NIV via the RAM cannula in the inpatient setting when they were unable to tolerate conventional NIV interfaces. Additionally, the RAM cannula was well-tolerated by children and there were no associated complications.
Studies have demonstrated the utility of NIV via the RAM cannula in infants with prematurity hospitalized in the neonatal ICU and for escalation and de-escalation of respiratory support in the cardiac ICU.4,5,9 De Jesus Rojas et al 10 reported a retrospective study of 18 children (mean age 7 ± 6.3 years) who used outpatient NIV via the RAM cannula for an average duration of 8.4 months. Similar to our study, patients had a variety of underlying diagnoses such as OSA, Trisomy 21, and RLDs and used the RAM cannula due to intolerance of conventional interfaces, to reduce dyspnea, and to avoid tracheostomy. In contrast to the study by De Jesus Rojas et al, the patients in our study were younger and predominantly <1 year of age. This suggests that outpatient NIV via the RAM cannula can be utilized even in infants. Infants have a greater risk for airway obstruction and gas exchange abnormalities due to anatomical and physiological factors. 13 In a single-center study of 29 infants who received home CPAP therapy for a variety of etiologies, Joshi et al 7 reported that CPAP is an effective long-term therapy during infancy. Similar to our study, patients had underlying diseases like Trisomy 21, RLDs, and craniofacial disorders and some children were weaned from CPAP therapy. In contrast to the study by Joshi et al 7 where nasal masks were the most used interfaces for CPAP therapy, patients in our study used the RAM cannula for NIV. Therefore, utilizing home NIV via the RAM cannula may permit time for airway and lung growth and potential improvement in OSA.
Families may seek long-term NIV for their child to avoid tracheostomy, especially when their child has a life-limiting diagnosis.2,10 Indeed, mechanical ventilation via tracheostomy is associated with increased burden of care, delayed speech, increased respiratory infections, and potentially fatal tracheostomy-related accidents such as tracheal bleeding, obstruction, and accidental decannulation.2,8 Despite the increasing prevalence of children using long-term home NIV, there are limited options for NIV interfaces in children that may affect adherence to NIV.2,3 Successful use of NIV may depend on several variables including a comfortable and well-fitting interface, motivation of the patient and their parents, and cooperation of the child. The challenges to finding a well-fitting NIV interface include a limited variety of pediatric interface options and facial anatomical abnormalities that may preclude a good mask fit.1,2,10 In contrast to the conventional NIV interfaces that include a mask and headgear, the RAM cannula consists of nasal prongs that fit in the patient’s nares and may be better tolerated by children using home NIV. In this study, 3 patients transitioned from the RAM cannula to conventional NIV interfaces due to increased respiratory requirements rather than intolerance or discomfort with the RAM cannula.
In this study, the indications for home NIV therapy during infancy and the utilization of the RAM cannula for outpatient NIV were similar to prior reports.7,10 In our study, many patients who used NIV via the RAM cannula had genetic conditions such as Trisomy 18 and Trisomy 21 complicated by sleep-disordered breathing and chronic respiratory failure. Some patients require continuous ventilator support that may be challenging to use with conventional NIV interfaces that are generally meant for use during sleep. 1 However, some of the patients in this study used the RAM cannula for continuous NIV suggesting that the RAM cannula could be utilized in children requiring full-time NIV. One of the adverse effects of long-term NIV via conventional NIV masks is facial growth impairment possibly related to the pressure of the mask of the developing facial bones.1,2,14 The RAM cannula occupies less area on the face and is a nasal prong interface; therefore, we speculate that there could be lower risk for facial growth abnormalities. However, the effects of long-term NIV via the RAM cannula on facial growth need further systematic evaluation.
In our study, some patients could not be discharged home with NIV via the RAM cannula due to requirements of increased respiratory support necessitating conventional NIV interfaces or tracheostomy. These findings suggest that clinicians considering the RAM cannula for outpatient NIV must carefully monitor the oxygen saturations, work of breathing, and carbon dioxide levels to ensure optimal gas exchange with NIV via the RAM cannula. Indeed, studies have demonstrated that only 60% to 70% of the ventilator set pressures were delivered to the infant using an appropriately sized RAM cannula. Smaller RAM cannula sizes relative to the size of the nares may lead to significant reduction in pressure transmission.6,15 The ideal RAM cannula size should fill approximately 80% of the nares. 12 Claassen et al 9 reported that clinicians using the RAM cannula for bubble CPAP therapy would need to increase ventilator pressures to compensate for pressure losses and to achieve adequate lung inflation. These studies highlight the importance of selecting an appropriately sized RAM cannula and adjusting ventilator settings to achieve optimal oxygenation and ventilation.6,9,15 Additionally, in our study, due to interface leaks, ventilator alarms could not be programmed when patients used NIV via the RAM cannula. Therefore, patients were instructed to use pulse oximetry as a monitoring device when they used NIV.
The median CPAP pressure reported by Joshi et al in 29 infants using home CPAP therapy with conventional nasal interfaces was 5.7 cm H2O. In patients using home NIV via the RAM cannula, De Jesus Rojas et al reported a mean CPAP setting of 7 cm H2O and BPAP settings of IPAP 15 cm H2O, EPAP 6 cm H2O, and respiratory rate of 13 per minute. Although the median CPAP setting (8 cm H2O) in our study was similar to the CPAP settings reported by De Jesus Rojas et al, 10 they were higher than the CPAP settings used by Joshi et al 7 in infants using CPAP via conventional nasal masks possibly due to interface leaks. The BPAP settings in our study were higher than the settings used by De Jesus Rojas et al. 10 This could be attributed to the age differences, interface leaks, inherent clinical features, and diagnoses of patients in these studies. Therefore, clinicians planning to use home NIV via the RAM cannula should pay close attention to the cannula size and ventilator settings, and increase ventilator settings, if required. Optimal NIV settings are best identified by performing polysomnography. 16 This entails titration of settings per established polysomnography standards using CPAP/BPAP device generated airflow signals that requires an adequate mask seal.17,18 Joshi et al 7 reported improvement in the apnea-hypopnea index during polysomnogram CPAP titration in infants receiving CPAP therapy via conventional interfaces. However, due to mask leak limitations with the RAM cannula and the anticipated effects on airflow signals, NIV titration via polysomnography could not be performed.
With advances in neonatal care and ventilation strategies, there is an increased survival of extremely preterm infants with severe BPD. Although some patients with severe BPD may require a tracheostomy for ventilation access, other patients may continue requiring respiratory support following extubation for a prolonged duration. 19 Our study demonstrates that home NIV via the RAM cannula could be used in some patients with severe BPD to facilitate hospital discharge, to allow time for lung growth and development, and to avoid tracheostomy. Indeed, in our study, at 6-month follow-up, patients with BPD using home NIV via the RAM cannula were either weaned off NIV or weaned to supplemental oxygen therapy highlighting the utility of home NIV in some patients with BPD.
Our study was limited by a single center retrospective study design with a relatively small sample size. Follow-up data was only collected for 6 months after initiation of home NIV therapy via the RAM cannula. Therefore, long-term outcomes of children using the RAM cannula for home NIV require further study. Although the parents reported tolerance and adherence to NIV, ventilator downloads and adherence data were not collected. Since patients did not undergo polysomnography to titrate NIV settings using the RAM cannula, future studies should evaluate the best practices for selecting eligible patients for home NIV and titration of NIV settings with the RAM cannula. In addition, our study lacked systematic measurements of oxygen saturations, carbon dioxide levels, and work of breathing before and after initiation of NIV via the RAM cannula.
Conclusion
Our study demonstrates the utility of outpatient NIV via the RAM cannula in children with a variety of underlying diagnoses until clinical improvement or tolerance of conventional NIV interfaces, and for avoidance of tracheostomy.
