A pilot study to assess short-term physiologic outcomes of transitioning infants with severe bronchopulmonary dysplasia from ICU to two subacute ventilators.

INTRODUCTION: This study was designed to evaluate short-term physiologic outcomes of transitioning neonates with bronchopulmonary dysplasia (BPD) from intensive care unit (ICU) ventilators to both the Trilogy 202 (Philips Healthcare, Andover, MA) and LTV 1200 (CareFusion, Yorba Linda, CA) subacute ventilators. METHODS: Six infants with BPD requiring tracheostomies for support with a neonatal-specific ICU ventilator underwent placement of esophageal balloon catheters, airway pressure transducers, flow sensors, oxygen saturation (SpO2), and end tidal carbon dioxide (PETCO2) monitors. Noninvasive gas exchange, airflow, and airway and esophageal pressures (PES) were recorded following 20 min on the ICU ventilator. The infants were placed on the Trilogy 202 and LTV 1200 ventilators in random order at identical settings as the ICU ventilator. We measured noninvasive gas exchange, pressure-rate product (respiratory rate × ΔPES), ventilator response times, and the percentage of spontaneous breaths that triggered the ventilator at 20 min in each subject while being supported with each of the different subacute ventilators. RESULTS: The mean (SD) weight of the six infants was 4.983 (0.56) kg. There were no differences in heart rate (p = 0.51) or SpO2 (p = 0.97) but lower PETCO2, ΔPES, respiratory rate, pressure rate-product, response times, and greater percentage of subject initiated breaths that triggered the ventilator (p < 0.05) was observed with the Trilogy 202 than the LTV 1200. All six infants transitioned successfully from the ICU ventilator to the Trilogy 202 ventilator. CONCLUSION: In this small group of infants with BPD, the Trilogy 202 ventilator performed better than the LTV 1200. The improved subject efforts, per cent subject triggering, and response times observed with the Trilogy are likely related to differences in triggering algorithms, location of triggering mechanisms, and gas delivery system performance within the ventilators. These pilot data may be useful for informing future clinical study design and understanding differences in the level of support provided by different subacute ventilators in infants with BPD.

Inhaled Treprostinil Drug Delivery During Mechanical Ventilation and Spontaneous Breathing Using Two Different Nebulizers.

OBJECTIVES: To determine the feasibility of delivering inhaled treprostinil during mechanical ventilation and spontaneous unassisted ventilation using the Tyvaso Inhalation System and the vibrating mesh nebulizer. We sought to compare differences in fine particle fraction, and absolute inhaled treprostinil mass delivered to neonatal, pediatric, and adult models affixed with a face mask, conventional, and high-frequency ventilation between Tyvaso Inhalation System and with different nebulizer locations between Tyvaso Inhalation System and vibrating mesh nebulizer. DESIGN: Fine particle fraction was first determined via impaction with both the Tyvaso Inhalation System and vibrating mesh nebulizer. Next, a test lung configured with neonatal, pediatric, and adult mechanics and a filter to capture medication was attached to a realistic face model during spontaneous breathing or an endotracheal tube during conventional ventilation and high-frequency oscillator ventilator. Inhaled treprostinil was then nebulized with both the Tyvaso Inhalation System and vibrating mesh nebulizer, and the filter was analyzed via high-performance liquid chromatography. Testing was done in triplicate. Independent two-sample t tests were used to compare mean fine particle fraction and inhaled mass between devices. Analysis of variance with Tukey post hoc tests were used to compare within device differences. SETTING: Academic children's hospital aerosol research laboratory. MEASUREMENTS AND MAIN RESULTS: Fine particle fraction was not different between the Tyvaso Inhalation System and vibrating mesh nebulizer (0.78 ± 0.04 vs 0.77 ± 0.08, respectively; p = 0.79). The vibrating mesh nebulizer delivered the same or greater inhaled treprostinil than the Tyvaso Inhalation System in every simulated model and condition. When using the vibrating mesh nebulizer, delivery was highest when using high-frequency oscillator ventilator in the neonatal and pediatric models, and with the nebulizer in the distal position in the adult model. CONCLUSIONS: The vibrating mesh nebulizer is a suitable alternative to the Tyvaso Inhalation System for inhaled treprostinil delivery. Fine particle fraction is similar between devices, and vibrating mesh nebulizer delivery meets or exceeds delivery of the Tyvaso Inhalation System. Delivery for infants and children during high-frequency oscillator ventilator with the vibrating mesh nebulizer may result in higher than expected dosages.

Physiologic Effects of 3 Different Neonatal Volume-Targeted Ventilation Modes in Surfactant-Deficient Juvenile Rabbits.

BACKGROUND: Different brands of volume-targeted modes may vary the location of tidal volume (VT) monitoring and whether peak inspiratory pressure is adjusted based on inspiratory, expiratory, or leak-compensated VT. These variables may result in different levels of support provided to patients, especially when an endotracheal tube (ETT) leak is present. We hypothesized that there would be no differences in gas exchange, triggering, or work of breathing between volume-targeted modes of 3 different brands of equipment in a surfactant-deficient, spontaneously breathing animal model with and without an ETT leak. METHODS: Twelve rabbits (mean ± SD 1.61 ± 0.20 kg) were sedated, anesthetized, intubated, lavaged with 0.9% saline solution, and randomized in a crossover design so that each animal was supported by 3 different volume-targeted modes at identical settings with and without an ETT leak. After 30 min, arterial blood gas, VT, and esophageal and airway pressure were recorded for each condition, and pressure-rate product and percentage of successfully triggered breaths were calculated. RESULTS: Gas exchange and the pressure-rate product were not different between the ventilators in the absence of an ETT leak. When an ETT leak was introduced, volume-guarantee modes allowed a higher percentage of triggered breaths and peak inspiratory pressure, which resulted in higher minute ventilation, pH, and lower PaCO2 than the pressure-regulated volume control mode (P < .05). CONCLUSIONS: When a moderate ETT leak was present, volume-targeted modes that used proximal VT monitoring and triggering with adaptive leak compensation capabilities appeared more effective in providing ventilation support than did a ventilator that used measurements obtained from the back at the ventilator and does not have leak compensation.

The conversion to metered-dose inhaler with valved holding chamber to administer inhaled albuterol: a pediatric hospital experience.

BACKGROUND: Metered-dose inhalers with valved holding chambers (MDI-VHCs) have been shown to be equivalent to small-volume nebulizers (SVNs) for the delivery of bronchodilators in children. At Seattle Children's Hospital and Regional Medical Center we sought to implement the conversion from SVN to MDI-delivered albuterol in nonintubated patients receiving intermittent treatments. METHODS: There were 4 distinct interventions used to plan and implement this conversion program: (1) literature review, (2) product selection, (3) policy and operational changes, and (4) staff training. Bronchodilator administration guidelines and clinical pathways for asthma and bronchiolitis were revised to recommend MDI-VHC use in lieu of SVNs. Computerized physician order sets were amended to indicate MDI-VHC as the preferred method of delivering inhaled albuterol in children with asthma and bronchiolitis. Data from administrative case mix files and computerized medication delivery systems were used to assess the impact of our program. RESULTS: MDI-VHC utilization increased from 25% to 77% among all non-intensive-care patients receiving albuterol, and from 10% to 79% among patients with asthma (p < 0.001). Duration of stay among patients with asthma was unchanged after conversion to MDI-VHC (p = 0.53). CONCLUSIONS: Our program was very successful at promoting the use of MDI-VHC for the administration of albuterol in our pediatric hospital. Duration of stay among patients with asthma did not change during or since the implementation of this program.

Iloprost drug delivery during infant conventional and high-frequency oscillatory ventilation.

Iloprost is a selective pulmonary vasodilator approved for inhalation by the Food and Drug Administration. Iloprost has been increasingly used in the management of critically ill neonates with hypoxic lung disease. This in vitro study was designed to test the hypothesis that aerosol drug delivery could be effectively administered to infants with both conventional ventilation and high-frequency oscillatory ventilation (HFOV). A neonatal test lung model configured with newborn lung mechanics was ventilated with a conventional ventilator and an HFOV with standard settings. A vibrating-mesh nebulizer was placed (1) proximal to the patient airway in the inspiratory limb between the humidifier probe and patient wye (conventional) as well as between the vent circuit and the endotracheal tube (ETT) for HFOV and (2) between the ventilator and humidifier (distal). Iloprost was nebulized in three separate runs using three new nebulizers in each of the circuit locations. A collecting filter was placed at the distal end of the ETT for each trial. Iloprost was quantified using high-performance liquid chromatography. The percentage of nominal dose delivered was greater with the nebulizer placed proximal to the airway for conventional ventilation (10.74% ± 2%) and HFOV (29% ± 2%) than with it placed in the distal position (2.96% ± 0.2% vs. 0.96% ± 0.8%, respectively; P < 0.05). Drug delivery in proximal position was nearly threefold greater during HFOV than during conventional ventilation. In conclusion, iloprost drug delivery was best achieved when the nebulizer was placed proximal to the patient airway during neonatal mechanical ventilation. Drug delivery appears to be more efficient during HFOV than during conventional ventilation.

Bronchodilator delivery during simulated pediatric noninvasive ventilation.

BACKGROUND: Noninvasive ventilation (NIV) is usually applied using bi-level positive airway pressure devices, and many of these devices use a single-limb patient circuit with an integrated leak port to purge the circuit of exhaled carbon dioxide. Sometimes bronchodilator therapy is indicated in pediatric patients, but there have been no studies of the optimal nebulizer position, with respect to leak, during pediatric NIV. We hypothesized that there would be no differences in albuterol delivery with a vibrating-mesh nebulizer between 3 different positions/exhalation leak valve combinations in the patient circuit during simulated pediatric NIV. METHODS: A simulated upper airway model was attached to a lung model that simulated spontaneous breathing. A noninvasive ventilator equipped with heated wire circuit and heated humidifier was attached to the lung model via a pediatric oronasal mask. Albuterol (5 mg) was delivered with a vibrating-mesh nebulizer, at 3 different circuit position/leak condition combinations: prior to the humidifier and leak valve; between the humidifier and leak valve; and integrated within the mask and after the leak. Albuterol was captured on a filter and quantified with chromatography. RESULTS: Greater albuterol mass was delivered to the filter with the nebulizer integrated into the mask than at any other testing condition (P < .001). In the conditions where the nebulizer was placed prior to the exhalation leak valve, greater drug delivery was observed when the nebulizer was placed proximal to the mask (position 2) than when placed prior to the humidifier (position 3, P = .002). CONCLUSIONS: Albuterol delivery during simulated pediatric NIV was affected by the position of the nebulizer in relation to the expiratory leak valve and the nebulizer's distance from the filter. A vibrating-mesh nebulizer placed intra-mask may provide a better alternative for medication delivery than those previously used during pediatric NIV.