Egan's Chapter 40

Aerosol Drug Deposition is influenced by:

a. inspiratory flow rate, flow pattern, RR, inhaled volume, I:E ratio, breath-holding

Key mechanisms of aerosol deposition:

- Inertial impaction

- Gravimetric sedimentation

- Brownian diffusion

only ________ of ______ will be inhaled

only fraction of emitted aerosol (dose) will be inhaled

only _____ of ______ is deposited in lungs

only fraction of inhaled (respirable dose) is deposited in lungs

What is amount of drug inhaled called?

inhaled mass

What portion is respirable mass?

Portion of inhaled mass that can reach lower airways

Inertial impaction: what is the primary deposition mechanism for larger particles

Greater than 5 µm

The greater the mass and velocity of moving object...

The greater the inertia and tendency of that object to continue moving along its set path

Sedimentation occurs when...

aerosol particles settle out of suspension and are deposited due to gravity

sedimentation: primary mechanism for deposition of small particles

1-5 µm

breath-holding after inhalation of aerosol...

increases sedimentation adn distribution across lungs

the greater the mass of particle

the faster it settles

Brownian diffusion: primary deposition mechanism for very small particles deep within the lungs

less than 3 µm

Upper airway: nose, larynx, trachea

- Recommended MMAD

- 5 to greater than 50 µm

Lower airways

- Recommended MMAD

- 2 to 5 µm

Parenchyma: alveolar region

- Recommended MMAD

- 1 to 3 µm

Parenchyma

- Recommended MMAD

- Less than 0.1 µm

Particle Size: methods to measure medical aerosol particle distribution:

- Cascade impaction

•MMAD—mass median aerodynamic diameter

- Laser diffraction

•VMD—volume median diameter

Particle size depends on three factors:

1.Substance being nebulized

2.Method used to generate the aerosol

3.Environmental conditions

Particle size: heterodisperse:

contains particles of many different sizes

Particle size: 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 and more heterodisperse aerosols

Primary hazard of aerosol drug therapy:

adverse RXN to medication

Possible hazards of aerosol therapy:

- Infection

- Airway reactivity

- Pulmonary and systemic effects of bland aerosols

- Drug concentration changes during nebulization

- Eye irritation à ex. Atrovent (anticholinergic), worsens some forms of glaucoma (nebulizer)

- Secondhand exposure to aerosol drugs

What do you do if your patient has a glaucoma and needs to use a nebulizer?

put a bacterial filter on the end of the hand held nebulizer

pMDI: pressurized canister containing prescribed drug in volatile propellant is combined with...

surfactant and dispersing agent

HFA is the propellant used

What is the most commonly prescribe method of aerosol therapy in the U.S. and why?

pMDI

b/c it is protable, compact, and easy to use

provides multidose convenience

BUT has serious limitation (lacks counter to indicate number of doses remaining in canister)

Most pMDIs are

"press and breathe"

Aerospan

Has a built-in valveless spacer that improves hand-breath coordination

Breath-actuated pMDIs

•Incorporate trigger activated during inhalation

•Reduce need for patient/caregiver to coordinate metered dose inhaler actuation with inhalation

Tempo Inhaler "orphan medication"

breath actuated

Factors affecting pMDI performance and drug delivery

- Temperature

•This problem has been less serious with the newer HFA pMDIs, temp lower than 10 C decreases output of MDIs

- Nozzle size and cleanliness

•As debris builds up on nozzle or actuator orifice, emitted dose is reduced

- Priming

•Shaking device and releasing one or more sprays into air when pMDI is new or has not been used for a while

•Mixes drug and propellant

•Required to provide adequate dose

- Timing of actuation intervals

•When propellants are released, device cools and changes aerosol output

pMDIs: aerosol delivery characteristics

- (MMAD 2-6 µm)

- About 80% of aerosol deposits in oropharynx

- Pulmonary deposition ranges between 10% and 20% in adults and larger children

•Breath hold allows maximal deposition

DPI technique

- Patients must generate inspiratory flow rate of at least 40-60 L/min to produce respirable powder aerosol

- DPIs should not be used by infants, small children, those who cannot follow instructions, and patients with severe airway obstruction

- Requires cleaning in accordance with product label

Pneumatic (Jet) Nebulizer: most nebulizers are powered by...

high-pressure oxygen or air.

Pneumatic (Jet) Nebulizer: provided by ....

portable compressor, compressed gas cylinder (E cylinder), or 50-psi wall outlet

Pneumatic (Jet) Nebulizer: factors affecting nebulizer performance

1. nebulizer design

2. flow* --> faster the flow, the shorter the treatment

3. gas source *

4. density* --> 5-20 mL of medication

5. humidity & temperature

6. characteristics of drug formulation

flow rate for Pneumatic (Jet) nebulizer

8 L/min

Continuous nebulizer with simple reservoir (SVN)

May increase inhaled dose by 5% to 10%, or increase inhaled dose from 10% to 11% with 6-inch piece of reservoir tube

Continuous nebulizer with collection reservoir bag (SVN)

1. Bag reservoirs hold aerosol generated during exhalation

2. Allows small particles to remain in suspension for inhalation with next breath while larger particles rain out

3. Attributed to 30% to 50% increase in inhaled dose

3.Breath enhanced (BE) (SVN)

Generate aerosol continuously, utilizing system of vents and one-way valves

Breath actuated nebulizer (BAN) (SVN)

Can increase inhaled aerosol mass by three- to fourfold over conventional continuous nebulization

SVN technique

•Selection of delivery method (mask or mouthpiece) is based on patient ability, preference, and comfort

Small particle aerosol generator (SPAG)

1. The regulator is connected to two flowmeters that separately control flow to the nebulizer and flow through the drying chamber

2. Nebulizer flow should be maintained at approximately 7 L/min with total flow from both flowmeters not less than 15 L/min

In addition to the inhaler, what other equipment would be needed to teach the patient?

I. Spacer device

II. Pulse oximeter

III. Peak flowmeter

I only

After performing the inhalation, the RT instructs the patient to perform a breath holding maneuver. The purpose of this maneuver is to _________________________.

A. promote strong cough

B. improve inertial impaction

C. improve venous return

D. increase medication delivery

D. increase medication delivery

While attempting to administer albuterol via SVN to a patient who had a recent CVA, the RT notes the patient is unable to hold the nebulizer or keep her lips sealed on the mouthpiece. The RT should:

A. provide subcutaneous administration of the medication

B. switch to an MDI

C. discontinue the medication

D. utilize an aerosol mask for delivery

D. utilize an aerosol mask for delivery

An MDI is ordered for a patient who is intubated and being mechanically ventilated and humidified via HME. Which of the following is the most appropriate way to administer the bronchodilator?

A. Place the MDI actuation spacer between the HME and endotracheal tube and use

B. Place the MDI in the expiratory limb of the ventilator circuit

C. Remove the HME altogether and deliver an SVN instead of an MDI

D. Recommend changing the delivery method to a SVN

A. Place the MDI actuation spacer between the HME and endotracheal tube and use

An alert adult patient with asthma is receiving bronchodilator therapy via SVN during a hospitalization. What should the RT do in regard to this therapy when the patient is ready for discharge?

A. Recommend training in home use of the SVN

B. Recommend administration of the drug via IPPB

C. Recommend oral administration of the medication

D. Recommend an MDI and MDI instruction

D. Recommend an MDI and MDI instruction

Which of the following devices is most suitable for delivery of Ribavirin?

A. Ultrasonic nebulizer

B. SPAG (small particle aerosol generator)

C. Optineb

D. Atomizer

B. SPAG (small particle aerosol generator)

Match the desired location of nebulized particle(s) to its recommended MMAD: Upper airway: nose, larynx, and trachea

5 to > 50 micrometers

Match the desired location of nebulized particle(s) to its recommended MMAD: Lower airways

2 to 5 micrometers

Match the desired location of nebulized particle(s) to its recommended MMAD: Parenchyma: alveolar region

1 to 3 micrometers

Match the desired location of nebulized particle(s) to its recommended MMAD: Parenchyma

< 0.1 micrometers

What are the recommended steps for nebulizer cleaning and disinfecting in the home?(Include hot and cold methods).

1) Clean the nebulizer parts using dish detergent and water.

2) Disinfect using either hot or cold method.

1. Cold method: soak in 70% isopropyl alcohol for 5 minutes then in3% hydrogen peroxide for 30 minutes.

2. Hot method: boil for 5 minutes, microwave for 5 minutes, wash inthe dish washer (if it can achieve greater than 158 F or 70 C for 30minutes)

3) Rinse (if you use a cold disinfectant) with sterile water.

4) Air-dry thoroughly prior to storage.

What is the recommendation (2 steps) for a hand-held disposable nebulizer in thehospital?

1) After each use you should rinse out the residual volume with sterile waterthen wipe down the mask/mouthpiece with an alcohol pad

2) Discard the nebulizer every 24 hours

What are the common manufacturer cleaning instruction recommendations for ametered-dose inhaler? Why is this done?

The common manufacturer cleaning instruction is to rinse the actuator well underwarm running water for approximately 30 seconds (one end then the other) atleast once a week. It is import to make sure the metal canister does not get wet.The purpose in rinsing the actuator is to remove any medication buildup that canblock the spray medication.

What is the recommended cleaning strategy for a (dry) powder inhaler?

You should firstly avoid getting it wet at all costs to avoid inhibiting properfunction and delivery of proper medication. You must use proper hand hygienebefore use, wipe the mouthpiece off with a clean DRY cloth (e.g. paper towel),and properly store the dry inhaler when not in use.

What are 4 respiratory therapist responsibilities for education and prevention withpatients on aerosol therapy and infection control?

1) Be knowledgeable of the standard procedures for using all the aerosoldelivery devices

.2) To be aware of the infection prevention and control guidelines/recommendations in regard to handling/care of the aerosol deliverydevices.

3) Another responsibility is to understand the patient-related issues in aerosoltherapy to enhance the patient's education efforts.

4) Being a patient advocate, while seeking support and guidance from allstakeholders to assist you in providing quality care, education, and time inregard to the patient that we serve

What is SPAG specifically used for?

administration of ribavirin, typically for infants w/ RSV

Provide a simple, short explanation of atelectasis

Atelectasis is when there is a pulmonary complication, such as lung collapse, due to alveolar collapse.

Provide a simple, short explanation of sustained maximal inspiration

A sustained maximal inspiration is a long slow deep breath followed by a 3-4 second hold that is meant to simulate a yawn or sigh.

Scenario: You're interacting with a patient who has never performed an Incentive Spirometer. Complete the following sentences:

The purpose of this treatment is to...

This device will...

o The purpose of this treatment is to coach your lungs into expanding more and more until you reach your maximal inspiration.

o This device will mimic a natural sigh.

What is the primary purpose of CPAP?

The primary purpose of a CPAP is to continuously provide pressure while you sleep to keep your airways open.

What caused compression atelectasis?

Compression atelectasis is caused the transthoracic pressure exceeds the trans alveolar pressure. This is caused by a mechanism that increases the pressure gradient.

Why are postoperative patients at highest risk for development of atelectasis?

Postoperative patients are at highest risk for development of atelectasis because problems coughing effectively which reduces their ability to take deep breaths and can cause retained secretions that can cause absorption atelectasis.

IPPB is used to treat atelectasis. Specifically, when would IPPB be indicated compared with IS?

We would use the IPPB instead of the IS either when the IS has failed or the patient's vital capacity is less than 15 mL/kg.

List 4 contraindications to IPPB.

Tension pneumothorax

ICP > 15 mmHg

Hemodynamic instability

Active hemoptysis

List three current positive airway pressure (PAP) therapies.

CPAP

IPPB

PEP

What are two contraindications to CPAP therapy and briefly explain.

A recent facial, oral, or skull surgery could be irritated by the fitted mask because of how particular the fit is.

Someone who is hemodynamically unstable should not use a CPAP because the CPAP reduces stroke volume and this could pose other health risks.

What are 4 procedures that increase the risk of atelectasis occurring?

Anesthesia use

Use of muscle relaxants

Cardiopulmonary surgery

What are 4 patient (comorbidity) related factors associated with increased risk of atelectasis occurring?

1. Not being able to clear the airway

2. Inability to open up the glottis causing mucus build up

3. Difficulty swallowing liquids causing a pool of saliva and mucus in pharynx

4. Excessive pharyngeal secretions that are similar to post-nasal drip

What happens to West lung zone 1 during general anesthesia and why?

During general anesthesia there is an increase in alveolar dead space and decrease in patient tidal volume. This is because of the positive pressure from the general anesthesia that causes the collapse from the alveolar pressure.

What does diffusion impairment reflect and what are 3 underlying lung diseases that could contribute to this?

- Diffusion impairment reflects the result of reduction in global perfusion of the lungs and reduction in the conductance of alveolar capillary membrane.

- Underlying lung diseases that can cause this: COPD Sarcoidosis Cystic fibrosis

What are 2 prevention methods for prevention and treatment of atelectasis?

- Chest physiotherapy

- Use of IS (incentive spirometry)