Chapter 36 Aerosol Drug Therapy

Chapter 36 Aerosol Drug Therapy
Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Learning Objectives Define the term “aerosol.”
Describe how particle size, motion, and airway characteristics affect aerosol deposition. Describe how aerosols are generated. List the hazards associated with aerosol drug therapy. Describe how to select the best aerosol drug delivery system for a given patient. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Learning Objectives (cont.)
Describe how to initiate and modify aerosol drug therapy. State the information patients need to know to properly self-administer drug aerosol therapy. Describe how to assess patient response to bronchodilator therapy at the point of care. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Learning Objectives (cont.)
Describe how to apply aerosol therapy in special circumstances. Describe how to protect patients and caregivers from exposure to aerosolized drugs. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Introduction Aerosol is suspension of solid or liquid particles in gas
In clinical setting, medical aerosols are generated with devices that physically disperse matter into small particles & suspend them into gas Atomizers Nebulizers Inhalers Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Introduction (cont.) Medication aerosol provides higher therapeutic index Higher local drug concentration in lung Lower systemic effects Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Characteristics of Therapeutic Aerosols
Aerosol Output Mass of fluid or drug contained in aerosol Output rate is mass of aerosol generated per unit of time Varies depending on different nebulizers & inhalers used Emitted dose describes mass of drug leaving mouthpiece as aerosol Measured by collecting aerosol that leaves nebulizer on filters Gravimetric analysis measures aerosol weight Assay measures quantity of drug Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Characteristics of Therapeutic Aerosols (cont.)
Particle size Depends on 3 factors Substance being nebulized Method used Environmental conditions Methods to measure medical aerosol particle distribution include: Cascade impaction Laser diffraction Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Particle size (cont.) Geometric standard deviation (GSD) describes variability of particle sizes Heterodisperse aerosols are aerosols with particles of different sizes Monodisperse aerosols are aerosols with particles of similar sizes Greater the GSD, wider range of particle sizes & more heterodisperse aerosols Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Deposition Only fraction of emitted aerosol (emitted dose) will be inhaled Only fraction of inhaled (respirable dose) is deposited in lungs Amount of drug inhaled called “inhaled mass.” Portion of inhaled mass that can reach lower airways is “respirable mass” Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Deposition (cont.) Influenced by Inspiratory flow rate Flow pattern Respiratory rate Inhaled volume I:E ratio Breath-holding Key mechanisms of aerosol deposition include: Inertial impaction Gravimetric sedimentation Brownian diffusion Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Key mechanisms causing aerosol deposition include all of the following, except:
Sedimentation inertial impaction Brownian diffusion osmosis Answer: D Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Deposition (cont.) Inertial impaction Occurs when aerosol in motion collides with & are deposited on surface Primary deposition mechanism for larger particles (>5 µm). Greater mass & velocity of moving object, then greater inertia & greater tendency of that object to continue moving along its set path Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Inertial impaction of large particles, the masses of which tend to maintain their motion in straight lines. As airway direction changes, the particles are deposited on nearby walls. Smaller particles are carried around corners by the airstream and fall out less readily. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Deposition (cont.) Sedimentation Occurs when aerosol particles settle out of suspension & are deposited due to gravity Represents primary mechanism for deposition of small particles (1-5 µm) Breath-holding after inhalation of aerosol increases sedimentation & distribution across lungs Greater mass of particle, the faster it settles Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure 36-02A. Effect of mass on particle size. Large particles (A) are more susceptible to the force of gravity than smaller particles (B), which are more affected by the bombardment of molecules deposited by diffusion. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Deposition (cont.) Brownian diffusion Primary deposition mechanism for very small particles (<3 µm) deep within lung Particles between 1 & 0.5 µm have very low mass & are so stable that most remain in suspension & are exhaled back into environment Particles <0.5 µm have greater retention rate in lungs Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Range of particle size for common aerosols in the environment and the influence of inertial impactions, sedimentation, and diffusion. (Modified from Yu CP, Nicolaides P, Soong TT, et al: Effect of random airway sizes on aerosol deposition. Am Ind Hyg Assoc J 40:999, 1979.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aging Process by which aerosol suspension changes over time How aerosol ages depends on: Composition of aerosol Initial size of its particles Particle size can change due to evaporation or hygroscopic water absorption Time in suspension Ambient condition Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Total lung deposition of a fine aerosol of particles 1 µm in diameter in healthy adults and in subjects with obstructive airway disease. Numbers over the bar indicate the percentage increase above normal value.COPD, Patients with chronic obstructive pulmonary disease; Dp, particle diameter; SAD, smoker with symptoms of small airways disease; f, respiratory rate; VT, tidal volume. (Modified from Kim CS: Methods of calculating lung delivery and deposition of aerosol particles. Respir Care 45:695, 2000.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Hazards of Aerosol Therapy
Primary hazard of aerosol drug therapy is adverse reaction to medication Other possible hazards: Infection Airway reactivity Pulmonary & systemic effects of bland aerosols Drug concentration changes during nebulization Eye irritation Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Hazards of aerosol drug therapy include all of the following, except:
Infection Hyperinflation systemic effects eye irritation Answer: B Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol Drug Delivery Systems
Pressurized metered-dose inhalers (pMDIs) Pressurized canister containing prescribed drug in volatile propellant combined with surfactant & dispersing agent Most commonly prescribed method of aerosol therapy Portable, compact, & easy to use Provides multidose convenience Has serious limitation Lacks counter to indicate number of doses remaining in canister Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol Drug Delivery Systems (cont.)
Pressurized metered-dose inhalers (cont.) Most pMDIs are “press and breathe” Variations of pMDIs Breath-actuated pMDIs Incorporates trigger activated during inhalation Reduces need for patient/caregiver to coordinate metered dose inhaler actuation with inhalation Aerocount Autohaler Flow-triggered Eliminates need for hand-breath coordination Easihaler & Tempo Breath-actuated Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Components of a pMDI, including function of the metering valve. (From Gardenhire DS: Rau’s respiratory care pharmacology, ed 8, St. Louis, 2012, Mosby.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Factors affecting pMDI performance & drug delivery Temperature Decreased temperature (<10º C) decrease output of CFC pMDIs Nozzle size & cleanliness As debris builds up on nozzle or actuator orifice, emitted dose is reduced Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Factors affecting pMDI performance & drug delivery (cont.) Priming Shaking device & releasing one or more sprays into air when pMDI is new or has not been used for awhile Mixes drug & propellant Required to provide adequate dose Timing of actuation intervals When propellants are released, device cools & changes aerosol output Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol delivery characteristics pMDIs can produce particles in respirable range (MMAD 2-6 µm) ~80% of aerosol deposits in oropharynx Pulmonary deposition ranges between 10% & 20% in adults & larger children Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Technique for use of pMDI Most patients do not use proper technique Thorough education of patient can take up to 30 minutes MDI should be actuated at beginning of inspiration with mouthpiece held 4 cm in front of open mouth Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Technique for use of pMDI (cont.) Concerns with open-mouth technique Ipratropium bromide administration along with poor coordination can result in drug being sprayed into eyes Anticholinergic agents have been associated with increased ocular pressure Steroid pMDIs can increase incidence of opportunistic oral yeast infection & dysphonia Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

pMDI accessory devices Breath-actuated pMDIs Trigger actuation when patient inhales Useful when patient cannot coordinate inhalation with actuation Spacers Simple valveless extension device that adds distance between pMDI outlet & patient’s mouth Reduces oropharyngeal deposition & need for hand-breath coordination Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

pMDI accessory devices (cont.) Holding chambers Incorporates one or more valves that prevent aerosol in chamber from being cleared on exhalation Provides less oropharyngeal deposition, higher respirable drug dosages, & better protection from poor hand-breath coordination than simple spacers Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure pMDI and accessory devices consisting of spacer and holding chambers. All of the accessory devices reduce oropharyngeal deposition. Small volume spacers (e.g., Optihaler [Philips Respironics, Murrysville, PA] and Myst Assist [Philips Respironics, Murrysville, PA]) offer no additional advantage, but large volume spacers (e.g., toilet paper roll and Ellipse [Ellipse Technologies, Irving, CA]) improve inhaled aerosol with delay between actuation and inspiration. Only the bag (e.g., Inspirease [Schering Plough, Kenilworth, NJ]) and valved holding chambers (e.g., Aerochamber [Invicare, Elyria, OH], Optichamber [Philips Respironics, Murrysville, PA], Ace [Smiths Medical, Kent, UK], and Medispacer [Cardinal Health, Dublin, OH]) protect the patient from blowing the dose away when the pMDI is actuated during expiration. (Modified from Wilkes W, Fink J, Dhand R: Selecting an accessory device with a metered-dose inhaler: variable influence of accessory devices on fine particle dose, throat deposition, and drug delivery with asynchronous actuation from a metered-dose inhaler. J Aerosol Med 14:351, 2001.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Dry powder inhalers Breath-actuated dosing system Patient creates aerosol by drawing air through dose of finely milled drug powder Dispersion of powder into respirable particles depends on creation of turbulent flow in inhaler Flow is function of ability of patient to inhale powder with sufficiently high inspiratory flow rate Do not use propellants & do not require hand-breath coordination needed for pMDIs Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Aerosolization of dry powder. (Modified from Dhand R, Fink J: Dry powder inhalers. Respir Care 44:940, 1999.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Dry powder inhalers (cont.) Categorized based on design of their dose containers Unit-dose DPI Aerolizer & Handihaler dispense individual doses of drug from punctured gelatin capsules Multiple-unit dose DPI Diskhaler contains case of four or eight individual blister packets of medication on disk inserted into inhaler Multiple dose Drug Reservoir DPI Twisthaler, Flexhaler, & Diskus are preloaded with quantity of pure drug sufficient for dispensing 120 doses of medication Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure 36-14A. Some currently available DPIs: A and B, Multiple-dose dpi: diskus inhaler C, Unit-dose dpi: aerolizer. (GlaxoSmithKline, used with permission.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Dry powder inhalers (cont.) Factors affecting DPI performance & drug delivery include Intrinsic resistance & inspiratory flow rate Exposure to humidity & moisture Patient’s inspiratory flow ability Technique for use of DPI Patients must generate inspiratory flow rate of at least L/min to produce respirable powder aerosol DPIs should not be used by infants, small children, those who cannot follow instructions, & patients with severe airway obstruction Requires cleaning in accordance with product label Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

requires high inspiratory flow most units are single dose
What is a disadvantage of using a pressurized metered-dose inhaler versus a dry-powder inhaler? requires high inspiratory flow most units are single dose determining the amount of drug remaining contamination Answer: C Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Pneumatic (jet) nebulizers Most nebulizers are powered by high-pressure oxygen or air provided by portable compressor, compressed gas cylinder, or 50-psi wall outlet Factors affecting nebulizer performance nebulizer design gas pressure gas density medication characteristics Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure 36-18A. A, Small-volume jet nebulizer with tube reservoir for liquid drug delivery. B, Schematic of a small-volume jet nebulizer. (DeVilbiss Healthcare, Somerset PA.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

medication characteristics ambient relative humidity
The main factors the affect the performance of a pneumatic jet nebulizer include all of the following, except: nebulizer design gas pressure medication characteristics ambient relative humidity Answer: D Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Small volume nebulizers (SVN) Four categories Continuous nebulizer with simple reservoir May increase inhaled dose by 5-10%, or increase inhaled dose from 10 to 11% with 6-inch piece of reservoir tube Continuous nebulizer with collection reservoir bag Bag reservoirs hold aerosol generated during exhalation Allows small particles to remain in suspension for inhalation with next breath while larger particles rain out Attributed to 30-50% increase in inhaled dose Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Small volume nebulizers (SVN) (cont.) Four categories Breath enhanced (BE) Generate aerosol continuously, utilizing system of vents & one-way valves Breath actuated nebulizer (BAN) Can increase inhaled aerosol mass by 3-4 fold over conventional continuous nebulization Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure 36-19A. Variety of available aerosol devices. A and C, Passive meshB, Active vibrating mesh. (Courtesy Omron Healthcare, Inc. Bannockburn, IL.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Small volume nebulizers (SVN) (cont.) Technique Slow inspiratory flow optimize SVN aerosol deposition Selection of delivery method (mask or mouthpiece) is based on patient ability, preference, & comfort Infection control issues Nebulizers should be cleaned & disinfected, or rinsed with sterile water, & air dried between uses Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Large-volume jet nebulizers Also used to deliver aerosolized drugs to lungs Particularly useful when traditional dosing strategies for patients with bronchospasm are not effective Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Large-volume jet nebulizers (cont.) Special large-volume nebulizers provide CBT HEART Westmed HOPE Small-particle aerosol generator (SPAG) Designed specifically for administration of ribavirin Incorporates drying chamber with its own flow control to produce stable aerosol Concerns include caregiver exposure to drug & drug precipitation can jam breathing valves in mechanical ventilator circuit Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Hand-bulb atomizers & spray pumps Used to administer sympathomimetic, anticholinergic, antiinflamatory, & anesthetic aerosols to upper airway Deposition with hand-bulb atomizer applied to nose occurs mostly in anterior nasal passages with clearance to nasopharynx Spray pump produces aerosol suspension with large particle size, which are ideal for upper airway deposition Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Ultrasonic nebulizers (USNs) Uses piezoelectric crystal to produce aerosol Crystal converts electrical energy into high-frequency vibrations to produce aerosol Capable of higher aerosol outputs ( ml/min) & higher aerosol densities than are conventional jet nebulizers Output is directly affected by amplitude setting Particle size is inversely proportional to frequency of vibrations Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Ultrasonic nebulizers (cont.) Large-volume USN Incorporates air blowers to carry mist to patient Primarily used for delivery of bland aerosol therapy or sputum induction Low flow through nebulizer is associated with smaller particles & higher mist density Temperature of solution placed in USN increases during use Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Ultrasonic nebulizers (cont.) Small-volume USNs Used to deliver aerosolized medications Can be used to deliver bronchodilators, antibiotics, & anti-inflammatory agents Can be used to administer undiluted bronchodilator to patient with severe bronchospasm Patient’s inspiratory flow draws aerosol from nebulizer into lung Does not add extra gas flow to ventilator circuit, reducing need to change & reset ventilator & alarm settings during aerosol administration Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Small volume USN designed for use with mechanical ventilation. A vibrating piezoceramic crystal generates ultrasonic waves that pass through couplant (sterile buffer water) and the medication cup to generate a fountain (or standing wave) of medication that produces aerosol particles. (Courtesy Siemens, Tarrytown, New York.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Vibrating mesh (VM) nebulizers Types Active Utilizes dome-shaped aperture plate (attached to piezo ceramic element), containing more than 1000 funnel-shaped apertures Exit velocity of aerosol is low (<4 m/sec) Particle size can range between 2-3 µm (MMAD), varying with exit diameter of apertures Can nebulize single drops as small as 15 µL of formulations containing small & large molecules, suspensions, microsuspensions, & liposomes Includes Aeroneb Go pro, Solo, & eFlow (Pari) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Vibrating mesh (VM) nebulizers (cont.) Types Passive Utilizes mesh separated from ultrasonic horn by liquid to be nebulized Includes NEU-22 (Omron) & I-neb (respironics) Residual drug volume range from mL Care should be exercised when transitioning to these devices Greater percentage of standard unit doses are emitted as aerosol Higher doses may create adverse effects Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

igure 36-26A. VM nebulizers use two basic configurations. Active VM nebulizer (A) has an aperture plate with funnel-shaped holes vibrated by a piezoelectric transducer surrounding the aperture plate found in the Aeroneb Solo (Aerogen, Galway, Ireland) and eFlow (Pari, Midlothian, VA; A). Passive VM nebulizer (B) uses an ultrasonic horn to push fluid through a stationary mesh found in the NEU-22 (Omron; B) and iNeb (Phillips/Respironics, Murrysville, PA). Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

New nebulizer designs for liquids AERs Has built-in electronic monitoring capabilities for measuring inspiratory flow rate (IFR) Dose administered is logged to provide record of treatments Uses drug solution in unit-dose, sterile, preservative-free blister pack containing µL of fluid Emitted dose is more than 70% of dose contained in blister with inspiratory flow rate ranging from L/min Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

New nebulizer designs for liquids (cont.) Respimat Small hand held inhaler Uses mechanical energy to create aerosol from liquid solutions to produce low-velocity spray (10 mm/sec) that delivers unit dose in single actuation Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Smart nebulizers I-neb (Phillips respironics) Breath-actuated passive vibrating mesh nebulizer Has adaptive aerosol delivery that monitors pressure changes & inspiratory time for patient’s first three consecutive breaths Drug is aerosolized over 50% of inspiratory maneuver during fourth & subsequent breaths Has been released for delivery of prostacyclin Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure The iNeb (bottom left) is a smart nebulizer with adaptive aerosol delivery (AAD) and targeted inhalation mode (TIM). AAD delivers a precise preset dose with variation between patients. A microprocessor tracks the patient’s breathing pattern on a running average of the previous three breaths, generating aerosol for 50% of the predicted inspiration (upper left). TIM progressively guides the patient to take longer inspirations, increasing to achieve optimal inhalation duration (right). Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Smart nebulizers (cont.) Akita (Activaero) Controls inspiratory flow to keep it slow (12-15 lpm) & reduce impaction loss of aerosols in upper airways Patient pulmonary function is stored on smart card programmed to tell device when to generate aerosol during inhalation Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Special medication delivery issues for infants & children Smaller airway diameter than adults Breathing rate is faster Nose breathing filters out large particles Lower minute volumes Patient cooperation & ability varies with age & developmental ability Aerosols should never be administered to crying child Crying reduces lower airway deposition of aerosol medication Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure 36-28A. Drug deposition of radiolabeled albuterol in a young child (A)inhaling with a pMDI/space through a non-tightly fitted facemask; (B) inhaling with a nebulizer through a non-tightly fitted facemask; (C) inhaling with a pMDI/spacer through a tightly fitted facemask, screaming during inhalation; (E, F) inhaling with a pMDI/spacer through a tightly fitted facemask, quietly inhaling; and (G, H) inhaling from a nebulizer through a tightly fitted facemask, quietly inhaling. (Redrawn from Erzinger, S, Schueepp, KG, Brooks-Wildhaber, J, et al: Facemasks and aerosol delivery in vivo. J Aerosol Med 2007;20(suppl 1.):S78-S84.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Blow-by technique Used if patient cannot tolerate mask treatment Practitioner directs aerosol from nebulizer toward patient’s nose & mouth distance of several inches from face Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol Drug Delivery Systems (cont.) 36-29
Figure Selecting an aerosol drug delivery system. When the need is established for aerosol drug delivery, the formulations available for the prescribed medication should be determined. If a pMDI is available, it is the first choice for cost and convenience. The patient’s ability to coordinate actuation with inspiration and the need to reduce oropharyngeal deposition (e.g., steroids) determine need for a holding chamber or a breath-actuated unit. Nebulizers are the first choice when the formulation is available only as a solution. When the ordered medication is unavailable for inhalation use, the RT should recommend a substitution to the ordering physician. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Assessment-Based Bronchodilator Therapy Protocols

Assessment-Based Bronchodilator Therapy Protocols (cont.)
Role of RT Assess patient response Ongoing patient assessment is key to effective bronchodilator therapy protocol Peak flow measurement can provide trends if same device is used from one treatment to next Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Assessment-Based Bronchodilator Therapy Protocols (cont.)
Role of RT(cont.) Assess patient response Components of patient assessment Patient interviewing Observation Measurement of vital signs Auscultation Blood gas analysis Oximetry Conduct dose-response titration to determine best dosage for patients with moderate obstruction Patient education Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Special Considerations
Acute care & “off label” use Off-label use Clinicians may explore & consider nonstandard methods (doses, frequency, & devices) for administration of approved inhaled drugs to patients in acute care environment Use of drugs that have not been approved for inhalation, ranging from heparin to certain antibiotics Should be avoided when approved & viable alternative exists Off-label administration should always be backed by appropriate departmental or institutional policies & procedures Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Special Considerations (cont.)
Continuous nebulization for refractory bronchospasm CBT with nebulized albuterol doses ranging from 5-20 mg/hour have proved to be safe for adult & pediatric patients with severe asthma Patient carefully assessed every 30 minutes for first 2 hours; then hourly Patient must be observed for adverse drug responses Positive response indicated by increase in PEFR of at least 10% after first hour of therapy Goal is at least 50% of predicted value Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure Algorithm for CBT for patients younger than 5 years with pediatric asthma in extremis. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

The goal for PEFR is at least 50% of predicted value.
Which of the following is NOT true regarding continuous bronchodilator therapy? CBT has proved to be safe for adult and pediatric patients with severe asthma. An increase in PEFR of at least 10-15% after the first hour of therapy indicates a positive response. Once CBT is started, the patient need not be assessed throughout the therapy. The goal for PEFR is at least 50% of predicted value. Answer: D Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol administration to mechanically ventilated patients 4 primary forms of aerosol generator used to deliver aerosols during mechanical ventilation SVN USN VM pMDI with third part adapter Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Aerosol administration to mechanically ventilated patients (cont.) Techniques used for assessing response to bronchodilator Measure change in difference between peak & plateau pressures Drop in peak pressure during mechanical ventilation suggests effective bronchodilation Automatic positive end-expiratory pressure levels may decrease in response to bronchodilators Breath-to-breath variations Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Non-invasive ventilation Administered with standard & bi-level ventilators Bi-level ventilators often utilize flow turbine, with fixed valve or leak in circuit which permits excess flow to vent to atmosphere High-flow nasal oxygen Type & location of nebulizer used with high-flow nasal oxygen, cannula size, respiratory pattern, & oxygen flow affect inhaled dose Heliox (80:20) improve aerosol delivery at higher flow rates Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Intrapulmonary percussive ventilation Provides high-frequency oscillation of airway while administering aerosol particles Aerosol generator should be placed in circuit as close to patient’s airway High frequency oscillatory ventilation Administration of albuterol sulfate via VM placed between ventilator circuit & patient airway delivers >10% of dose to infants & adults Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Controlling Environmental Contamination
Nebulized drugs may enter room directly from nebulizer or during patient exhalation Pentamidine & ribavirin were associated with health risks to caregivers Continuous pneumatic nebulizers produce greatest amount of second-hand aerosol Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Use of one-way valves & filters can help Negative-pressure rooms & treatment booths are useful strategies Personal protective equipment is recommended when caring for patient with disease that can be spread by airborne route Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Figure In vitro model. (From Bhashyam AR, Wolf MT, Marcinkowski AL, et al: Aerosol delivery through nasal cannulas: an in vitro study. J Aerosol Med Pulm Drug Deliv 21:181, 2008.) Figure Emerson treatment booth provides containment of aerosol during therapy. Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

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