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Biomedical subjects

James B Fink

Publications and source records attributed to James B Fink.

16 recordsLinked to original sources
PubMed2006

The history and physics of heliox.

Since the discovery of helium in 1868, it has found numerous applications in industry and medicine. Its low density makes helium potentially valuable in respiratory care applications, to reduce work of breathing, improve distribution of ventilation, reduce minute volume requirement, and improve aerosol delivery. This review includes a brief history of the use of heliox (a mixture of helium and oxygen) and addresses issues related to the physics of gas flow when heliox is used. Specifically covered are the Hagen-Poiseuille equation, laminar versus turbulent flow, the Reynolds number, orifice flow, Bernoulli's principle, Graham's law, wave speed, and thermal conductivity.

Animals↗
PubMed2006

Opportunities and risks of using heliox in your clinical practice.

Helium-oxygen mixture (heliox) has been advocated for clinical use since 1934, and there has been a growing array of clinical applications. Until recently, administering heliox has required jury-rigging by modifications and/or extension of available devices not designed for use with heliox. This paper reviews devices required to administer heliox and considers how devices designed to deliver air and/or oxygen have been adapted for use with heliox. Use of devices outside of their design limits adds risk and liability, whereas using Food-and-Drug-Administration cleared devices for heliox administration reduces the risk and liability.

Airway Resistance↗
PubMed2005

Aerosol deposition in neonatal ventilation.

Lung deposition of inhaled drugs in ventilated neonates has been studied in models of questionable relevance. With conventional nebulizers, pulmonary deposition has been limited to 1% of the total dose. The objective of this study was to assess lung delivery of aerosols in a model of neonatal ventilation using a conventional and novel electronic micropump nebulizer. Aerosol deposition studies with 99mTc diethylenetriamine pentaacetate (99mTc-DTPA) were performed in four macaques (2.6 kg) that were ventilated through a 3.0-mm endotracheal tube (with neonatal settings (peak inspiratory pressure 12-14 mbar, positive end-expiratory pressure 2 mbar, I/E ratio 1/2, respiratory rate 40/min), comparing a jet-nebulizer MistyNeb (3-mL charge, 4.8 microm), an electronic micropump nebulizer operating continuously [Aeroneb Professional Nebulizer (APN-C); 0.5-mL charge, 4.6 microm], and another synchronized with inspiration [Aeroneb Professional Nebulizer Synchronized (APN-S); 0.5-mL charge, 2.8 microm]. The amount of radioactivity deposited into lungs and connections and remaining in the nebulizer was measured by a gamma counter. Despite similar amounts of 99mTc-DTPA in the respiratory circuit with all nebulizers, both APN-S and APN-C delivered more drug to the lungs than MistyNeb (14.0, 12.6, and 0.5% in terms of percentage of nebulizer charge, respectively; p = 0.006). Duration of delivery was shorter with APN-C than with the two other nebulizers (2 versus 6 and 10 min for the APN-S and the MistyNeb, respectively; p < 0.001). Electronic micropump nebulizers are more efficient to administer aerosols in an animal model of ventilated neonates. Availability of Aerogen's electronic micropump nebulizers offers new opportunities to study clinical efficacy and risks of aerosol therapy in ventilated neonates.

Administration, Inhalation↗
PubMed2005

An inhaled matrix metalloprotease inhibitor prevents cigarette smoke-induced emphysema in the mouse.

Inadequately regulated proteolytic activity is responsible for the chronic lung tissue degeneration and irreversible loss of pulmonary function that define emphysema. In this study, we show that an inhaled broad-spectrum matrix metalloprotease inhibitor, ilomastat, can provide protection against the development of emphysema in cigarette smoke-treated mice. Control animals were exposed to daily cigarette smoke for 6 months. As has been reported previously, cigarette smoke was seen to increase significantly the recruitment of macrophages into the lungs of these animals, leading to concomitant alveolar airspace enlargement and emphysema. In animals treated daily with nebulized ilomastat for 6 months, lung macrophage levels were greatly reduced, and neutrophil accumulation was also inhibited. Corresponding reductions in airspace enlargement of up to 96% were observed. These striking observations suggest that delivery of ilomastat directly into the lungs of smoke-treated mice can not only inhibit lung tissue damage mediated by metalloproteases, but may also reduce that component of tissue degeneration mediated by excess neutrophil-derived products. Our data also suggest that the matrix metalloprotease inhibitors may represent a class of drugs that, when delivered by inhalation, could be used practically to treat cigarette smoking-related chronic obstructive pulmonary disease by modifying the course of the disease.

Administration, Inhalation↗
PubMed2005

Management of community-acquired pneumonia in the home: an American College of Chest Physicians clinical position statement.

The number of patients with community-acquired pneumonia (CAP) who are being treated at home is increasing for a variety of reasons. These reasons include the increased availability and cost considerations of oral antibiotics that have been shown to be effective, as well as the consideration of patient and family preferences. However, there is still considerable variability in strategies for the management of patients with CAP. This American College of Chest Physicians position statement, which was cosponsored by the American Academy of Home Care Physicians, provides recommendations on the various aspects of home care for patients with this condition. Included are recommendations for evaluation and diagnosis in the home environment and the determination of the site of care, and an outline of an in-home management plan. The position statement also provides recommendations for issues related to patient and caregiver commitment to the plan, and for monitoring and follow-up. Recommendations are directed toward immunocompetent adult patients with CAP who are at home or in other unskilled residential facilities. These patients can include previously healthy individuals or chronically ill individuals who choose not to go to the hospital, or hospitalized patients who are completing a hospital discharge plan. The recommendations in this statement take into consideration the best course of action for the patient, as determined by incorporating the most recent evidence with clinician judgment and patient preferences. These recommendations also consider the available resources. Therefore, these recommendations may not apply to every patient, and interventions may need to be structured based on the individual. In addition to providing recommendations for the home care management of patients with CAP, we hope that this clinical policy statement will alert readers to the need for more scientific evidence related to the clinical and psychosocial issues associated with managing this condition.

Caregivers↗
PubMed2005

Optimizing aerosol delivery by pressurized metered-dose inhalers.

The modern era of aerosol therapy began with the introduction of the Medihaler Epi in 1956, after a 13-year-old asthmatic told her father, an officer in the Riker company, that asthma medications should be as convenient to use as hair spray and she complained that the bulb atomizer leaked in her school bag. Since then, advances in technology have made aerosol delivery much more efficient, so that it is now the most widely used mode of medication delivery for chronic airways diseases. Today the pressurized metered-dose inhaler (pMDI) is a metal canister containing a mixture of propellants, surfactants, preservatives, and drug. However, pMDIs are underused in the United States. One barrier to use is the misconception related to pMDI effectiveness relative to small-volume nebulizers, especially among pediatricians. This is despite the strongest evidence of pMDI superiority, from well-controlled pediatric studies. In this manuscript we discuss ways to optimize the use of medications given via pMDI and examine recent changes in pMDI technology that will make drug delivery more efficient and consistent.

Administration, Inhalation↗
PubMed2005

Problems with inhaler use: a call for improved clinician and patient education.

Patient education is a critical factor in the use and misuse of medication inhalers. Inhalers represent advanced technology that is considered so easy to use that many patients and clinicians do not receive adequate training in their use. Between 28% and 68% of patients do not use metered-dose inhalers or powder inhalers well enough to benefit from the prescribed medication, and 39-67% of nurses, doctors, and respiratory therapists are unable to adequately describe or perform critical steps for using inhalers. Of an estimated 25 billion dollars spent for inhalers annually, 5-7 billion dollars is wasted because of inhaler misuse. Reimbursement and teaching strategies to improve patient education could substantially reduce these wasted resources. Problems with inhaler use, the cost of inhalers, and myths associated with inhalers are reviewed, with recommendations for strategies and techniques to better educate patients in inhaler use.

Administration, Inhalation↗
PubMed2004

Aerosol delivery to ventilated infant and pediatric patients.

Infants have low tidal volume, vital capacity, and functional residual capacity, and short respiratory cycles (low I:E ratio), which result in a low residence time for aerosol particles and, thus, low pulmonary deposition of aerosol particles (< 1% of the nominal dose), compared to adults (8-22%). Scintigraphy data suggest aerosol deposition of < 1% in both intubated and nonintubated infants. In vitro testing appears to overestimate pulmonary deposition, partly because in vitro testing does not account for exhaled aerosol. Animal models of infant ventilation tend to agree with data from human studies. However, though only a small percentage of the aerosol deposits in the lung, infants nevertheless receive considerably more aerosolized drug per kilogram of body weight than do adults. Efficient aerosol delivery to infants is challenging because of low deposition and high inter-patient and intra-patient variability, but existing systems can effectively delivery various aerosolized drugs, including bronchodilators, anti-inflammatories, and anti-infectives. Use of a nebulizer that has a low residual volume (of drug remaining in the device after nebulization) delivers up to 13%. Awareness of the variables that impact aerosol delivery efficiency can result in more effective treatment of mechanically ventilated infants.

Administration, Inhalation↗
PubMed2004

Device and equipment evaluations.

Device evaluation, which is an essential skill set for the respiratory therapist, ranges from comparing manufacturer's specifications to comprehensive device testing, either with patients or on the bench. Good device evaluations help guide decisions about device selection, procedure development, and risk and failure analysis. Poor evaluations cost time and money and fail to return value. Manufacturer's specifications alone are poor criteria for device selection, because of how and why those specifications are created and the potential gap between the manufacturer's test methods and the complexity of clinical situations. Proper clinical evaluation of devices with patients requires extensive preparation and resource expenditure, and clinical evaluations may not allow isolating key variables to determine specifics of device performance. In vitro testing, using models to simulate discrete components of device/patient interface, is less expensive and easier to conduct. This article discusses the process of experiment design and model development for device and equipment evaluations.

Biomedical Research↗
PubMed2003

The delivery of inhaled medication to the young child.

The effective and efficient delivery of aerosol medications involves physician factors (correct diagnosis and correct prescription of appropriate medications), device factors, and patient factors. For nearly all infants and children, the authors administer asthma medications either using a pMDI with a valved holding chamber or a DPI. Regardless of the device chosen, parent and patient education is critical for the appropriate use of the device, and frequent reinforcement of the educational message will often improve adherence and correct use.

Administration, Inhalation↗
PubMed2002

Positioning versus postural drainage.

For the past 70 years positioning and postural drainage have played an important role in increasing lung volumes, perfusion, oxygenation and mobilization of secretions. While gravity is not a primary mechanism for normal secretion clearance, it plays a major role in depth and pattern of ventilation, perfusion, and lymphatic drainage. Changing patient position, or turning patients on a regular basis, is a powerful tool in maintaining lung health in a broad range of patients. In contrast, postural drainage requires considerable investment of time, and has been shown to have limited benefit in most patients. Postural drainage has been shown to improve mobilization of secretions in patients with cystic fibrosis as well as patients who produce, and have difficulty clearing, large quantities of sputum. The benefits of postural drainage appear technique-dependent, requiring sufficient drainage time (3 - 15 min) for each position drained. The evidence does not support the use of vibration and percussion independent of active postural drainage. Exercise offers benefit in secretion clearance, which increases when combined with a program of postural drainage. In conclusion, routine turning, mobilization and exercise is important to maintain lung health in all patients, while postural drainage, properly applied, has been shown to improve secretion clearance in a relatively narrow range of patients with cystic fibrosis and excessive sputum production.

Contraindications↗
PubMed2002

Positive pressure techniques for airway clearance.

Positive airway pressure (PAP) has been used since the 1930s to improve oxygenation, increase lung volumes and reduce venous return. More recently, PAP has been identified as an effective method of splinting airway during expiration, improving collateral ventilation, increasing response to inhaled bronchodilators, and aiding secretion clearance in patients with cystic fibrosis and chronic bronchitis. A range of devices, administration techniques, and evidence supporting their clinical use is explored, suggesting that PAP is equivalent to postural drainage in the clearance of secretions. PAP produced by threshold and fixed orifice resistors generate different characteristic flow, and airway and esophageal pressure patterns that may contribute to different physiologic effects. Further clinical studies are required to better understand the effects of these differences.

Aerosols↗
PubMed2002

High-frequency oscillation of the airway and chest wall.

High-frequency oscillation (HFO), applied to either the airway or chest wall, has been associated with changes in sputum attributes and clearance. The evolution of evidence, both in vitro and in vivo, supporting the use of HFO is reviewed. Devices that apply HFO to the airway range from the relatively simple mechanical Flutter and Acapella devices to the more complex Percussionaire Intrapercussive Ventilators. and the Hayek Oscillator are designed to provide high-frequency chest wall compression. Operation and use of these devices are described with examples of differentiation of device types by characterization of flows, and airway and esophageal pressures. Although HFO devices span a broad range of costs, they provide a reasonable therapeutic option to support secretion clearance for patients with cystic fibrosis.

Cystic Fibrosis↗