Arzu Ari

Inhalation Therapy in Patients Receiving Mechanical Ventilation: An Update

Incremental gains in understanding the influence of various factors on aerosol delivery in concert with technological advancements over the past 2 decades have fueled an ever burgeoning literature on aerosol therapy during mechanical ventilation. In-line use of pressurized metered-dose inhalers (pMDIs) and nebulizers is influenced by a host of factors, some of which are unique to ventilator-supported patients. This article reviews the impact of various factors on aerosol delivery with pMDIs and nebulizers, and elucidates the correlation between in-vitro estimates and in-vivo measurement of aerosol deposition in the lung. Aerosolized bronchodilator therapy with pMDIs and nebulizers is commonly employed in intensive care units (ICUs), and bronchodilators are among the most frequently used therapies in mechanically ventilated patients. The use of inhaled bronchodilators is not restricted to mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) and asthma, as they are routinely employed in other ventilator-dependent patients without confirmed airflow obstruction. The efficacy and safety of bronchodilator therapy has generated a great deal of interest in employing other inhaled therapies, such as surfactant, antibiotics, prostacyclins, diuretics, anticoagulants and mucoactive agents, among others, in attempts to improve outcomes in critically ill ICU patients receiving mechanical ventilation.

In vitro comparison of heliox and oxygen in aerosol delivery using pediatric high flow nasal cannula

Drug administration via high flow nasal cannula (HFNC) has been described in pediatrics but the amount of albuterol delivery with an HFNC is not known. The purpose of this study is to quantify aerosol delivery with heliox and oxygen (O2) in a model of pediatric ventilation. A vibrating mesh nebulizer (Aeroneb Solo, Aerogen) was placed on the inspiratory inlet of a heated humidifier and heated wire circuit attached to a pediatric nasal cannula (Optiflow, Fisher & Paykel). Breathing parameters were tidal volume (Vt) 100 ml, respiratory rate (RR) 20/min, and I‐time of 1 sec. Albuterol sulfate (2.5 mg/3 ml) was administered through a pediatric HFNC with O2 (100%) and heliox (80/20% mixture). A total of 12 runs, using O2 and heliox were conducted at 3 and 6 L/min (n = 3). Drug was collected on an absolute filter, eluted and measured using spectrophotometry. The percent inhaled dose (mean ± SD) was similar with heliox and O2 at 3 L/min (11.41 ± 1.54 and 10.65 ± 0.51, respectively; P = 0.465). However at 6 L/min drug deposition was ≥2‐fold greater with heliox (5.42 ± 0.54) than O2 (1.95 ± 0.50; P = 0.01). Using a pediatric model of HFNC, reducing delivered flow from 6 to 3 L/min increased inhaled albuterol delivery ≥2‐fold but eliminated the increase in inhaled drug efficiency associated with heliox. Pediatr. Pulmonol. 2011; 46:795–801.

Aerosol Delivery Device Selection for Spontaneously Breathing Patients: 2012

Using an electronic literature search for published articles indexed in PubMed between January 1990 and August 2011, the update of this clinical practice guideline is the result of reviewing 84 clinical trials, 54 reviews, 25 in vitro studies, and 7 evidence-based guidelines. The recommendations below are made following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria: 1: It is recommended that selection of the appropriate aerosol generator and interface be made based on the patients age, physical and cognitive ability, cost, and the availability of the prescribed drug for use with a specific device. 2: Nebulizers and pressurized metered-dose inhalers (pMDIs) with valved holding chambers are suggested for use with children ≤ 4 years of age and adults who cannot coordinate the use of pMDI or dry-powder inhaler (DPI). 3: It is suggested that administration of aerosols with DPIs be restricted to patients ≥ 4 years of age who can demonstrate sufficient flow for the specific inhaler. 4: For patients who cannot correctly use a mouthpiece, aerosol masks are suggested as the interface of choice. 5: It is suggested that blow-by not be used for aerosol administration. 6: It is suggested that aerosol therapy be administered with a relaxed and nondistressed breathing pattern. 7: Unit dose medications are suggested to reduce the risk of infection. 8: It is suggested that nebulizer/drug combinations should be used as approved by the FDA. 9: It is recommended that healthcare providers know the correct use of aerosol generators; they should teach and periodically re-teach patients about how to use aerosol devices correctly. 10: It is suggested that intermittent positive-pressure breathing should not be used for aerosol therapy. 11: It is recommended that either nebulizer or pMDI can be used for aerosol delivery during noninvasive ventilation.

An In Vitro Evaluation of Aerosol Delivery Through Tracheostomy and Endotracheal Tubes Using Different Interfaces

BACKGROUND: Previous research reporting factors influencing aerosol delivery in intubated patients has been largely focused on the endotracheal tube (ETT) during mechanical ventilation, with little comparative analysis of effect of types of artificial airways and their interfaces on aerosol delivery during spontaneous breathing. The purpose of this study was to compare aerosol delivery via tracheostomy tube (TT) and ETT, using interfaces such as T-piece, tracheostomy collar, and manual resuscitation bag. METHODS: A teaching manikin was intubated with either an ETT (8.0 mm inner diameter) and TT (8 mm inner diameter). Both bronchi were connected to a collecting filter, attached to a sinusoidal pump simulating the breathing pattern of a spontaneously breathing adult (tidal volume 450 mL, respiratory rate 20 breaths/min, inspiratory-expiratory ratio 1:2). Albuterol sulfate (2.5 mg/3 mL) was nebulized through a jet nebulizer, using each airway and interface as appropriate (n = 3). Drug on the filter was eluted and analyzed with spectrophotometry, and expressed as mean percent of loaded dose delivered. Descriptive statistics, the Student t test, and one-way analysis of variance were applied. RESULTS: A greater percentage of nominal dose was delivered via TT than ETT with both T-piece (13.79 ± 2.59% vs 9.05 ± 0.70%) and manual resuscitation bag (45.75 ± 1.8% vs 27.23 ± 8.98%, P = .038 and P = .025, respectively). Use of manual resuscitation bag with both TT and ETT increased lung dose more than 3-fold. Inhaled dose with tracheostomy collar was (6.92 ± 0.81%) less than T-piece with TT (P = .01). CONCLUSION: In this adult model of spontaneous ventilation, aerosol therapy through ETT was less efficient than TT, while the manual resuscitation bag was more efficient than T-piece or tracheostomy collar.

Factors affecting bronchodilator delivery in mechanically ventilated adults

BACKGROUND Bronchodilators are increasingly being used in patients undergoing mechanical ventilation. There are multiple factors that affect bronchodilator delivery during mechanical ventilation. These factors can be classified into three categories: ventilator-related factors, circuit-related factors and device-related factors. AIMS The purpose of this paper is to review in depth each of the factors affecting bronchodilator delivery during mechanical ventilation. SEARCH STRATEGIES A literature search was undertaken using several databases including Cochrane, Pubmed, Medline, Cinahl and Science Direct. The literature search, although limited to the English language, covered materials from 1985 to May 2009. CONCLUSION Aerosolized bronchodilator delivery to mechanically ventilated patients is complex as a result of the multiple factors that affect the amount of aerosol deposited in the lower respiratory tract. When these factors are not carefully controlled and the optimum technique for aerosol delivery is not utilized, a greater proportion of the aerosol will deposit in the ventilator circuits and artificial airways decreasing the available dose to the patient. Attention to these factors and optimizing aerosol delivery techniques will help to reach therapeutic endpoints of bronchodilator therapy in patients receiving ventilatory support. RELEVANCE TO CLINICAL PRACTICE Bronchodilator delivery during mechanical ventilation is factor and technique dependent. A clear understanding of the factors affecting aerosol drug delivery during mechanical ventilation is very important in optimizing the efficiency of bronchodilator delivery in mechanically ventilated adults. Through the recommendations made in this paper, clinicians will be able to optimize both their technique and the therapeutic outcomes of aerosol drug delivery in patients receiving ventilator support.

Guidelines for aerosol devices in infants, children and adults: which to choose, why and how to achieve effective aerosol therapy

Multiple types of aerosol devices are commonly used for the administration of medical aerosol therapy to patients with pulmonary diseases. All of these devices have been shown to be effective in trials where they are used correctly. However, failure to operate any of these devices properly has been associated with poor clinical response and limited patient adherence to therapy. Therefore, the selection of the best aerosol device for the individual patient is very important for optimizing the results of medical aerosol therapy. This article presents the rationale for selecting the most appropriate aerosol device to administer inhaled drugs in specific patient populations, with emphasis on patient-, drug-, device- and environment-related factors and with a comparison between the available devices. The following recommendations for the selection of the ‘best’ aerosol device for each patient population are intended to help clinicians gain a clear understanding of the specific issues and challenges so that they can optimize aerosol drug delivery and its therapeutic outcomes in patients.

Aerosol delivery to intubated patients

Introduction: Approximately 20 million patients are intubated in the USA each year, primarily for the administration of drugs. While the vast majority of these medications are administered as gas or instilled, there is a growing practice of aerosol administration to intubated patients, often associated with mechanical ventilation. As no drugs have been approved for aerosol administration to intubated infants or adults, much of these practices are technically off-label. Areas covered: History and advances in aerosol delivery with methods to determine delivery, with variables that impact delivery and the evolution of new technology and techniques. A literature search was undertaken using several databases including Cochrane, PubMed, Medline, Cinahl and Science Direct, covered materials from 1885 through January 2013. Expert opinion: As aerosol deposition has increased with newer technologies from 1 – 3% up to 30 – 60%, there exists an opportunity to develop drugs to better treat these sickest of patients and address the current unmet medical need.

Aerosol Therapy in Pulmonary Critical Care

Aerosolized medications are routinely used for the treatment of critically ill patients. This paper reviews aerosol delivery devices with a focus on issues related to their performance in pulmonary critical care. Factors affecting aerosol drug delivery to mechanically ventilated adults and spontaneously breathing patients with artificial airways are reviewed. Device selection, optimum device technique, and unmet medical needs of aerosol medicine in pulmonary critical care are also discussed.

Comparison of HFNC, bubble CPAP and SiPAP on aerosol delivery in neonates: An in-vitro study

Aerosol drug delivery via high flow nasal cannula (HFNC), bubble continuous positive airway pressure (CPAP), and synchronized inspiratory positive airway pressure (SiPAP) has not been quantified in spontaneously breathing premature infants. Objectives: The purpose of this study was to compare aerosol delivery via HFNC, bubble CPAP, and SiPAP in a model of a simulated spontaneously breathing preterm infant. Working hypothesis: The types of CPAP systems and nebulizer positions used during aerosol therapy will impact aerosol deposition in simulated spontaneously breathing infants. Study design: Quantitative, comparative, in‐vitro study. Methodology: A breath simulator was set to preterm infant settings (VT: 9 ml, RR: 50 bpm and Ti: 0.5 sec) and connected to the trachea of an anatomical upper airway model of a preterm infant via collecting filter distal to the trachea. The HFNC (Optiflow; Fisher & Paykel), Bubble CPAP (Fisher & Paykel), and SiPAP (Carefusion) were attached to the nares of the model via each devices proprietary nasal cannula and set to deliver a baseline of 5 cm H2O pressure. Albuterol sulfate (2.5 mg/0.5 ml) was aerosolized with a mesh nebulizer (Aeroneb Solo) positioned1 proximal to the patient and2 prior to the humidifier (n = 5). The drug was eluted from the filter with 0.1 N HCl and analyzed via spectrophotometry (276 nm). Data were analyzed using descriptive statistics, t‐tests, and one‐way analysis of variance (ANOVA), with P < 0.05 significant. Results: At position 1, the trend of lower deposition (mean ± SD%) across devices was not significant (0.90 ± 0.26, 0.70 ± 0.16 and 0.59 ± 0.19, respectively; P = 0.098); however, in position 2, drug delivery with SiPAP (0.79 ± 0.11) was lower compared to both HFNC (1.30 ± 0.17; P = 0.003) and bubble CPAP (1.24 ± 0.24; p = 0.008). Placement of the nebulizer prior to the humidifier increased deposition with all devices (P < 0.05). Conclusions: Aerosol can be delivered via all three devices used in this study. Device selection and nebulizer position impacted aerosol delivery in this simulated model of a spontaneously breathing preterm infant. Pediatr Pulmonol. 2015; 50:1099–1106.

Quantifying Aerosol Delivery in Simulated Spontaneously Breathing Patients With Tracheostomy Using Different Humidification Systems With or Without Exhaled Humidity

BACKGROUND: Aerosol and humidification therapy are used in long-term airway management of critically ill patients with a tracheostomy. The purpose of this study was to determine delivery efficiency of jet and mesh nebulizers combined with different humidification systems in a model of a spontaneously breathing tracheotomized adult with or without exhaled heated humidity. METHODS: An in vitro model was constructed to simulate a spontaneously breathing adult (tidal volume, 400 mL; breathing frequency, 20 breaths/min; inspiratory-expiratory ratio, 1:2) with a tracheostomy using a teaching manikin attached to a test lung through a collecting filter (Vital Signs Respirgard II). Exhaled heat and humidity were simulated using a cascade humidifier set to deliver 37°C and >95% relative humidity. Albuterol sulfate (2.5 mg/3 mL) was administered with a jet nebulizer (AirLife Misty Max) operated at 10 L/min and a mesh nebulizer (Aeroneb Solo) using a heated pass-over humidifier, unheated large volume humidifier both at 40 L/min output and heat-and-moisture exchanger. Inhaled drug eluted from the filter was analyzed via spectrophotometry (276 nm). RESULTS: Delivery efficiency of the jet nebulizer was less than that of the mesh nebulizer under all conditions (P < .05). Aerosol delivery with each nebulizer was greatest on room air and lowest when heated humidifiers with higher flows were used. Exhaled humidity decreased drug delivery up to 44%. CONCLUSIONS: The jet nebulizer was less efficient than the mesh nebulizer in all conditions tested in this study. Aerosol deposition with each nebulizer was lowest with the heated humidifier with high flow. Exhaled humidity reduced inhaled dose of drug compared with a standard model with nonheated/nonhumidified exhalation. Further clinical research is warranted to understand the impact of exhaled humidity on aerosol drug delivery in spontaneously breathing patients with tracheostomy using different types of humidifiers.