Effect of face mask design on inhaled mass of nebulized albuterol, using a pediatric breathing model.

BACKGROUND: Aerosol face mask design and the distance at which the face mask is held from the face affect the delivery of nebulized medication to pediatric patients. OBJECTIVE: To measure the inhaled mass of nebulized albuterol with 3 types of pediatric face mask, at 3 different distances from the face, with a model of a spontaneously breathing infant. METHODS: We compared a standard pediatric face mask and 2 proprietary pediatric face masks (one shaped to resemble a dragon face, the other shaped to resemble a fish face). The albuterol was nebulized with a widely used jet nebulizer. Aerosol delivery with each type of mask was measured with the mask at 0 cm (ie, mask directly applied to the mannequin face), 1 cm, and 2 cm from the mannequin face. In each test the nebulizer was filled with a 3-mL unit dose of albuterol sulfate and powered by oxygen at 8 L/min, with a total nebulization time of 5 min. The mannequin face was connected to a lung simulator that simulated a spontaneously breathing infant. We measured inhaled mass by collecting the aerosol on a 2-way anesthesia filter that was attached to the back of the mannequin's oral opening via a 15-mm silicon adapter. We also measured residual drug left in the nebulizer, and estimated the drug lost to the atmosphere. RESULTS: The mean +/- SD inhaled percentage of the nominal dose values at 0 cm, 1 cm, and 2 cm, respectively, were 2.18 +/- 0.53%, 1.45 +/- 0.46%, and 0.92 +/- 0.51% with the standard mask; 2.65 +/- 0.55%, 1.7 +/- 0.38%, and 1.3 +/- 0.37% with the dragon mask; and 3.67 +/- 0.8%, 2.92 +/- 0.4%, and 2.26 +/- 0.56% with the fish mask. With all 3 masks there was a statistically significant difference (p < 0.001) in inhaled mass between the 0 cm and 2 cm distance. The fish mask had a significantly higher (p < 0.001) inhaled mass than the dragon mask or the standard mask, at all 3 distances. CONCLUSIONS: The inhaled mass of albuterol is significantly reduced when the mask is moved away from the face. The fish mask had significantly higher inhaled mass than the standard mask or the dragon mask, under the conditions we studied. Mask design may affect nebulized albuterol delivery to pediatric patients.

The importance of nonelectrostatic materials in holding chambers for delivery of hydrofluoroalkane albuterol.

INTRODUCTION: Electrostatic attraction of aerosolized particles to the inner walls of an aerosol holding chamber (HC) made from a nonconducting material can reduce medication delivery, particularly if there is a delay between actuation and inhalation. OBJECTIVE: Compare total emitted mass and fine-particle mass (mass of particles < 4.7 microm) of hydrofluoroalkane-propelled albuterol from similar-sized HCs manufactured from conductive material (Vortex), charge-dissipative material (AeroChamber Max), and nonconductive material (OptiChamber Advantage, ProChamber, Breathrite, PocketChamber, and ACE), with and without wash/rinse pretreatment of the HC interior with ionic detergent, and with 2-s and 5-s delays between actuation and inhalation. METHODS: All the HCs were evaluated (1) directly from their packaging (with no wash/rinse pretreatment) and (2) after washing with ionic detergent and rinsing and drip-drying. We used an apparatus that interfaced between the HC mouthpiece and the induction port of an 8-stage Andersen cascade impactor to simulate a poorly coordinated patient, with delays of 2 s and 5 s between actuation and inhalation/sampling, at 28.3 L/min. RESULTS: With the 2-s delay, the delivered fine-particle mass per actuation, before and after (respectively) wash/rinse pretreatment was: AeroChamber Max: 23.8 +/- 4.8 microg, 21.5 +/- 3.2 microg; Vortex: 16.2 +/- 1.7 microg, 15.5 +/- 2.0 microg; OptiChamber Advantage: 2.6 +/- 1.2 microg, 6.7 +/- 2.3 microg; ProChamber: 1.6 +/- 0.4 microg, 5.1 +/- 2.5 microg; Breathrite: 2.0 +/- 0.9 microg, 3.2 +/- 1.8 microg; PocketChamber: 3.4 +/- 1.6 microg, 1.7 +/- 1.6 microg; ACE: 4.5 +/- 0.9 microg, 5.4 +/- 2.9 microg. Similar trends, but greater reduction in aerosol delivery, were observed with the 5-s delay. Significantly greater fine-particle mass was delivered from HCs made from conducting or charge-dissipative materials than from those made from nonconductive polymers, even after wash/rinse pretreatment (p < 0.01). The fine-particle mass was also significantly greater from the AeroChamber Max than from the Vortex, irrespective of wash/rinse pretreatment or delay interval (p < 0.01). CONCLUSION: HCs made from electrically conductive materials emit significantly greater fine-particle mass, with either a 2-s or 5-s delay, than do HCs made from nonconducting materials, even with wash/rinse pretreatment.

Practical problems with aerosol therapy in COPD.

Inhaled aerosol drugs commonly used by patients with chronic obstructive pulmonary disease include short-acting and long-acting bronchodilators, as well as corticosteroids. These agents are available in a variety of inhaler devices, which include metered-dose inhalers (MDI), breath-actuated MDIs, nebulizers, and, currently, 5 different models of dry powder inhaler (DPI). There is evidence to suggest that multiple inhaler types cause confusion among patients and increase errors in patient use. Problems with MDIs include failure to coordinate inhalation with actuation of the MDI, inadequate breath-hold, and inappropriately fast inspiratory flow. Lack of a dose counter makes determining the number of remaining doses in an MDI problematic. Patient misuse of MDIs is compounded by lack of knowledge of correct use among health-care professionals. Several factors often seen with elderly patients have been identified as predictive of incorrect use of MDIs. These include mental-state scores, hand strength, and ideomotor dyspraxia. Holding chambers and spacers are partially intended to reduce the need for inhalation-actuation coordination with MDI use. However, such add-on devices can be subject to incorrect assembly. Possible delays between MDI actuation and inhalation, rapid inspiration, chamber electrostatic charge, and firing multiple puffs into the chamber can all reduce the availability of inhaled drug. Because they are breath-actuated, DPIs remove the need for inhalation-actuation synchrony, but there is evidence that patient errors in use of DPIs may be similar to those with MDIs. One of the biggest problems is loading and priming the DPI for use, and this may be due to the fact that every DPI model in current use is different. Medical personnel's knowledge of correct DPI use has also been shown to be lacking. The optimum inhalation profiles are different for the various DPIs, but, generally, chronic obstructive pulmonary disease patients have been shown to achieve a minimum therapeutic dose, although the inhaled amount may be suboptimal. A limitation of DPIs that have multidose powder reservoirs (eg, the Turbuhaler) is ambient humidity, which can reduce the released dose. Small-volume nebulizers are limited by bulk, treatment time, and variable performance, but are easy for patients to use. Important features identified by patients for an ideal inhaler are ease of use during an attack, dose counter, and general ease of use and learning. A breath-actuated-pMDI, such as the Autohaler, ranked at the top of inhaler preference in a study of 100 patients with airflow obstruction, compared to DPIs and MDIs. Short of a universal simple inhaler, patient and caregiver education remains the best solution to correct patient errors in use.

An investigation of nebulized bronchodilator delivery using a pediatric lung model of spontaneous breathing.

BACKGROUND: The literature lacks comparative data on nebulizer aerosol delivered via mask versus T-piece, to spontaneously breathing pediatric subjects. PURPOSE: To compare total inhaled drug mass delivered via standard pediatric aerosol mask versus via T-piece, with increasing distance. METHODS: We used a sample of 5 nebulizers, operated under manufacturers' conditions, with a standard pediatric aerosol mask and with a T-piece capped at one end, at 0 cm, 1 cm, and 2 cm from an inhalation filter placed at the inlet of a pediatric test lung. Inhaled drug mass was analyzed with spectrophotometry. Aerosol particle size was measured separately from the breathing simulations, using a laser particle sizer to determine fine-particle mass (particles < 4.7 mum) and fine-particle fraction as percent of total mass. The fine-particle fraction was used to estimate the fine-particle mass. RESULTS: The mean + SD values for inhaled drug mass as a percentage of nominal dose, at 0 cm, 1 cm, and 2 cm, with the mask were 2.88 + 0.79%, 1.61 + 0.65%, and 1.3 + 0.42%, respectively, and with the T-piece were 4.14 + 1.37%, 3.77 + 1.04%, and 3.47 + 0.64%, respectively. There was a statistically greater inhaled drug mass with T-piece than with mask, overall (p < 0.01), and a significant decrease with mask or T-piece as distance increased (p < 0.01). The difference between mask and T-piece for inhaled drug mass at 2 cm was statistically significant (p < 0.018). The mean + SD values for fine-particle mass estimated as a percentage of total drug mass at 0, 1, and 2 cm, with the mask were 1.39 + 0.36%, 0.78 + 0.29%, and 0.64 + 0.20%, respectively, and with the T-piece were 2.1 + 0.63%, 1.84 + 0.45%, and 1.71 + 0.27%, respectively. CONCLUSION: Inhaled drug mass was greater with T-piece than with a standard pediatric aerosol mask under the conditions studied.

Determinants of patient adherence to an aerosol regimen.

Patient adherence with prescribed inhaled therapy is related to morbidity and mortality. The terms "compliance" and "adherence" are used in the literature to describe agreement between prescribed medication and patient practice, with "adherence" implying active patient participation. Patient adherence with inhaled medication can be perfect, good, adequate, poor, or nonexistent, although criteria for such levels are not standardized and may vary from one study to another. Generally, nonadherence can be classified into unintentional (not understood) or intentional (understood but not followed). Failing to understand correct use of an inhaler exemplifies unintentional nonadherence, while refusing to take medication for fear of adverse effects constitutes intentional nonadherence. There are various measures of adherence, including biochemical monitoring of subjects, electronic or mechanical device monitors, direct observation of patients, medical/pharmacy records, counting remaining doses, clinician judgment, and patient self-report or diaries. The methods cited are in order of more to less objective, although even electronic monitoring can be prone to patient deception. Adherence is notoriously higher when determined by patient self-report, compared to electronic monitors. A general lack of adherence with inhaled medications has been documented in studies, and adherence declines over time, even with return clinic visits. Lack of correct aerosol-device use is a particular type of nonadherence, and clinician knowledge of correct use has been shown to be imperfect. Other factors related to patient adherence include the complexity of the inhalation regimen (dosing frequency, number of drugs), route of administration (oral vs inhaled), type of inhaled agent (corticosteroid adherence is worse than with short-acting beta2 agonists), patient awareness of monitoring, as well as a variety of patient beliefs and sociocultural and psychological factors. Good communication skills among clinicians and patient education about inhaled medications are central to improving adherence.

Characteristics of a successful respiratory therapy education program.

Because of the increasing demand for program effectiveness, program outcomes have become important for quality assessment in respiratory care education. Respiratory care programs and their institutions must ensure that programs in which they invest their time, energy, and money have there sources necessary to provide quality preparation of program graduates. To determine how well an educational program achieves its goal in producing competent respiratory therapists, respiratory therapy programs must be assessed through key personnel, teaching, clinical education, and enrollment management. The processes such as developing faculty,improving instruction and enhancing students' learning, and strengthening the structure of the respiratory therapy program with competent personnel and effective enrollment management practices determine the direction and rate of success of the respiratory care program at GSU.

Positive expiratory pressure device acceptance by hospitalized children with sickle cell disease is comparable to incentive spirometry.

BACKGROUND: The pulmonary complication in sickle cell disease known as acute chest syndrome (ACS) has potential for high morbidity and mortality. A randomized trial demonstrated that incentive spirometry (IS) reduces the rate of ACS, leading to a role for respiratory therapy in hospital management of sickle cell pain. However, use of IS can be limited by chest wall pain, or by difficulty with the coordinated inspiration in a young child. Intermittent positive expiratory pressure (PEP) therapy may be easier for a child's coordination and more comfortable than IS for a child with chest wall pain. PURPOSE: To compare PEP therapy with conventional IS for children hospitalized for sickle cell pain with respect to patient satisfaction, length of hospital stay, and progression to ACS. METHODS: This pilot study enrolled 20 children upon hospitalization for sickle cell pain in the thorax, randomly assigning them to either PEP (n = 11) or IS (n = 9) therapy, administered by a therapist hourly while awake. RESULTS: The randomization assigned an older distribution to PEP than IS (12.3 vs 8.8 y). Patient satisfaction was high for both respiratory care devices, and there was no difference between the PEP and IS groups (4.5 vs 4.4, p = 0.81). Length of hospital stay was similar (5 vs 4.3 d, p = 0.56). No children in either group progressed to ACS. CONCLUSION: These preliminary results show no difference in the primary outcomes in the 2 groups. Intermittent PEP therapy warrants further study as an alternative to IS for sickle cell patients at high risk for ACS, as effective preventive respiratory therapy.

The inhalation of drugs: advantages and problems.

Inhalation is a very old method of drug delivery, and in the 20th century it became a mainstay of respiratory care, known as aerosol therapy. Use of inhaled epinephrine for relief of asthma was reported as early as 1929, in England. An early version of a dry powder inhaler (DPI) was the Aerohalor, used to administer penicillin dust to treat respiratory infections. In the 1950s, the Wright nebulizer was the precursor of the modern hand-held jet-venturi nebulizer. In 1956, the first metered-dose inhaler (MDI) was approved for clinical use, followed by the SpinHaler DPI for cromolyn sodium in 1971. The scientific basis for aerosol therapy developed relatively late, following the 1974 Sugarloaf Conference on the scientific basis of respiratory therapy. Early data on the drug-delivery efficiency of the common aerosol delivery devices (MDI, DPI, and nebulizer) showed lung deposition of approximately 10-15% of the total, nominal dose. Despite problems with low lung deposition with all of the early devices, evidence accumulated that supported the advantages of the inhalation route over other drug-administration routes. Inhaled drugs are localized to the target organ, which generally allows for a lower dose than is necessary with systemic delivery (oral or injection), and thus fewer and less severe adverse effects. The 3 types of aerosol device (MDI, DPI, and nebulizer) can be clinically equivalent. It may be necessary to increase the number of MDI puffs to achieve results equivalent to the larger nominal dose from a nebulizer. Design and lung-deposition improvement of MDIs, DPIs, and nebulizers are exemplified by the new hydrofluoroalkane-propelled MDI formulation of beclomethasone, the metered-dose liquid-spray Respimat, and the DPI system of the Spiros. Differences among aerosol delivery devices create challenges to patient use and caregiver instruction. Potential improvements in aerosol delivery include better standardization of function and patient use, greater reliability, and reduction of drug loss.

Device selection and outcomes of aerosol therapy: Evidence-based guidelines: American College of Chest Physicians/American College of Asthma, Allergy, and Immunology.

BACKGROUND: The proliferation of inhaler devices has resulted in a confusing number of choices for clinicians who are selecting a delivery device for aerosol therapy. There are advantages and disadvantages associated with each device category. Evidence-based guidelines for the selection of the appropriate aerosol delivery device in specific clinical settings are needed. AIM: (1) To compare the efficacy and adverse effects of treatment using nebulizers vs pressurized metered-dose inhalers (MDIs) with or without a spacer/holding chamber vs dry powder inhalers (DPIs) as delivery systems for beta-agonists, anticholinergic agents, and corticosteroids for several commonly encountered clinical settings and patient populations, and (2) to provide recommendations to clinicians to aid them in selecting a particular aerosol delivery device for their patients. METHODS: A systematic review of pertinent randomized, controlled clinical trials (RCTs) was undertaken using MEDLINE, EmBase, and the Cochrane Library databases. A broad search strategy was chosen, combining terms related to aerosol devices or drugs with the diseases of interest in various patient groups and clinical settings. Only RCTs in which the same drug was administered with different devices were included. RCTs (394 trials) assessing inhaled corticosteroid, beta2-agonist, and anticholinergic agents delivered by an MDI, an MDI with a spacer/holding chamber, a nebulizer, or a DPI were identified for the years 1982 to 2001. A total of 254 outcomes were tabulated. Of the 131 studies that met the eligibility criteria, only 59 (primarily those that tested beta2-agonists) proved to have useable data. RESULTS: None of the pooled metaanalyses showed a significant difference between devices in any efficacy outcome in any patient group for each of the clinical settings that was investigated. The adverse effects that were reported were minimal and were related to the increased drug dose that was delivered. Each of the delivery devices provided similar outcomes in patients using the correct technique for inhalation. CONCLUSIONS: Devices used for the delivery of bronchodilators and steroids can be equally efficacious. When selecting an aerosol delivery device for patients with asthma and COPD, the following should be considered: device/drug availability; clinical setting; patient age and the ability to use the selected device correctly; device use with multiple medications; cost and reimbursement; drug administration time; convenience in both outpatient and inpatient settings; and physician and patient preference.

Searching the literature and selecting the right references.

The ability to locate published data on a topic is a fundamental skill in the research process, and it aids in formulating and refining a research question and planning the study. Searching the literature for published studies on a topic relevant to one's question requires knowledge of databases such as MEDLINE, Cumulative Index to Nursing and Allied Health, or Hospital Literature Index. PubMed provides access to MEDLINE and over 12 million citations in the medical literature. When searching in PubMed you can apply various "limits," such as what fields the search term is in (eg, author, title, text word, journal), type of report (eg, clinical trial, review, editorial), language, patient age, gender, and human or animal study. The "Boolean operators" (AND, OR, and NOT) can further focus and refine your search. However, to be sure that you retrieve all the files of interest and don't miss any files that might be critical to your understanding of the topic, you must search all fields and be careful not to exclude potentially important files with the NOT operator.

Performance comparison of nebulizer designs: constant-output, breath-enhanced, and dosimetric.

INTRODUCTION: Design differences among pneumatically powered, small-volume nebulizers affect drug disposition (percentage of the dose delivered to the patient, lost to deposition in the equipment, and lost via exhalation to ambient air) and thus affect drug availability and efficacy. OBJECTIVE: Evaluate in vitro the dose disposition with 5 nebulizer models, of 3 types (constant-output, breath-enhanced, and dosimetric), using simulated normal, adult breathing. METHODS: We compared 5 nebulizer models: 2 constant-output (Misty-Neb and SideStream), 1 breath-enhanced (Pari LCD), and 2 dosimetric (Circulaire and AeroEclipse). Each nebulizer was filled with a 3-mL unit-dose of albuterol sulfate and powered by oxygen at 8 L/min. The nebulizers were connected to an induction throat, connected to a breathing simulator. We measured (1) inhaled drug (subdivided into mass deposited in the induction throat and mass deposited in the filter at the distal end of the induction throat), (2) exhaled drug (lost to the ambient air), (3) drug lost to deposition in the apparatus, and (4) drug left in the unit-dose bottle. The duration of nebulization (until sputter) was measured with a stopwatch. All drug amounts were analyzed via spectrophotometry and expressed as a percentage of the total dose. RESULTS: The mean +/- SD inhaled drug percentages were: Misty-Neb 17.2 +/- 0.4%, SideStream 15.8 +/- 2.8%, Pari LCD 15.2 +/- 4.2%, Circulaire 8.7 +/- 1.0%, and AeroEclipse 38.7 +/- 1.3%. The mean +/- SD percentages of drug lost to the ambient air were: Misty-Neb 26.8 +/- 0.7%, SideStream 17.3 +/- 0.4%, Pari LCD 18.3 +/- 0.8%, Circulaire 12.3 +/- 0.8%, and AeroEclipse 6.6 +/- 3.3%. The mean +/- SD percentages of drug lost to deposition in the apparatus were: Misty-Neb 52.3 +/- 0.6%, SideStream 63.4 +/- 3.0%, Pari LCD 62.5 +/- 4.0%, Circulaire 75.8 +/- 0.5%, and AeroEclipse 51.0 +/- 2.1%. Duration of nebulization was shortest with the Circulaire and longest with the AeroEclipse (p < 0.05 via 1-way analysis of variance). CONCLUSIONS: The nebulizers we tested differ significantly in overall drug disposition. The dosimetric AeroEclipse provided the largest inhaled drug mass and the lowest loss to ambient air, with the test conditions we used. method.

Nebulized bronchodilator formulations: unit-dose or multi-dose?

BACKGROUND: Nosocomial infections linked to the use of multi-dose bronchodilator nebulizer formulations have been reported in the literature. OBJECTIVE: Survey American hospital respiratory therapy services to determine practice patterns, opinions, and awareness regarding unit-dose and multi-dose bronchodilator formulations. METHODS: A quota sample targeted 4 hospital size categories (0-100 beds, 101-200 beds, 201-400 beds, and > 400 beds) using a listing of general medical/surgical hospitals from the American Hospital Association. Hospitals were contacted via telephone to identify the director of respiratory therapy services, who was invited to complete a 29-item Web-based survey of their hospital practices and their opinions about and knowledge of issues with multi-dose and unit-dose bronchodilator formulations. RESULTS: One thousand forty-seven hospitals were recruited and 409 valid surveys were completed (completion rate 39%). The reported mean +/- SD percentage of unit-dose nebulizer treatments was 80.2 +/- 26.2%. Seventy-two percent (296) of respondents indicated having a policy and procedure manual that deals specifically with nebulized bronchodilator solutions, but only 107 reported having internal monitoring guidelines for compliance with those policies and procedures. Multi-dose bottles of bronchodilator concentrate were used with multiple patients in 77% of cases, and on average 9.7 +/- 8.5 patients were treated with the same multi-dose bottle. Eighty-one percent of respondents reported that treatments from multi-dose bottles are prepared at the bedside. The length of time a multi-dose bottle was kept (after being opened) ranged from 24 hours (8%) to 1 month (11%), and only 3% of respondents reported following manufacturers' recommendations. In the respondents' opinion the chief advantage of multi-dose was cost per dose (84%), and the chief advantage of unit-dose was less risk of contamination (92%). With other factors (therapist time, cost of saline diluent for multi-dose concentrate, dose-error, and contamination) considered, 73% thought that unit-dose vials were more cost-effective. Three hundred thirty-six respondents (82%) thought that a sterile, low-volume (0.5 mL) unit-dose vial of bronchodilator concentrate would be useful, and 249 (74%) of those 336 respondents indicated that such a formulation would replace multi-dose bottles. Only 56% of respondents knew about the evidence regarding the risk of contamination with multi-dose bottles. CONCLUSIONS: Multi-dose bottles of bronchodilator solution are used in approximately 20% of nebulizer treatments, and without strict adherence to infection control procedures they are a potential source of nosocomial infection. A sterile, low-volume unit-dose vial of bronchodilator concentrate would be a useful alternative to multi-dose concentrate for modifying doses or mixing drugs in nebulizer therapy.

Design principles of liquid nebulization devices currently in use.

Liquid nebulization is a common method of medical aerosol generation. Nebulizers are of 2 types: jet (or pneumatic) small-volume nebulizer, and ultrasonic nebulizer. Jet nebulizers are based on the venturi principle, whereas ultrasonic nebulizers use the converse piezoelectric effect to convert alternating current to high-frequency acoustic energy. Important variables for both types of nebulizer are treatment time required, particle size produced, and aerosol drug output. There are several advantages to jet nebulization, including that effective use requires only simple, tidal breathing, and that dose modification and dose compounding are possible. Disadvantages include the length of treatment time and equipment size. Design modifications to the constant-output nebulizer have resulted in breath-enhanced, open-vent nebulizers such as the Pari LC Plus and the dosimetric AeroEclipse. Ultrasonic nebulizers generally have a higher output rate than jet nebulizers, but a larger average particle size. Ultrasonic nebulizers can also substantially increase reservoir solution temperature, the opposite of jet nebulizer cooling. Drug concentration in the reservoir does not increase with ultrasonic nebulization, as it does with jet nebulization. Ultrasonic nebulizers have the same advantages as jet nebulizers. Ultrasonic nebulizers are more expensive and fragile than jet nebulizers, may cause drug degradation, and do not nebulize suspensions well. Neither type of nebulizer meets the criteria for an ideal inhaler: efficient and quick dose delivery with reproducibility, cost-effectiveness, and no ambient contamination by lost aerosol.