Airway Pharmacology

Douglas S. Gardenhire

Objectives

Upon the completion of the chapter activities and content review topics, the student should be able to:

1. Administer drugs.

2. Describe the three phases that constitute the course of drug action from dose to effect.

3. Describe the classes of drugs that are delivered via the aerosol route.

4. Compare the available aerosol formulations, brand names, and dosages for each specific drug class.

5. Select the appropriate drug class for a given patient or clinical situation.

Key Terms

Drug administration phase

Pharmacokinetic phase

Pharmacodynamic phase

Six rights of medication administration

Content Review Topics

Computerized Physician Order Entry (CPOE)

Global Initiative for Chronic Obstructive Lung Disease (GOLD)

Institute for Safe Medication Practice (ISMP)

National Asthma Education and Prevention Program (NAEPP)

Pulmonary medications

Equipment

Mock medication ampoules

Small-volume nebulizer

The primary objective of airway pharmacology is the delivery of inhaled aerosols to the respiratory tract for the diagnosis and treatment of pulmonary diseases. Because the administration of medications is such an important part of the daily activities of a respiratory therapist (RT), a deep understanding of them is essential. How medications work is an important part of the assessment process and in choosing the right medication to treat the pulmonary needs of your patients.

Three phases constitute the course of drug action from dose to effect: (1) the drug administration phase, (2) the pharmacokinetic phase, and (3) the pharmacodynamic phase. These three phases of drug action may be applied to treatment of the respiratory tract with bronchoactive inhaled agents and are defined in Box 18-1. Devices that are most commonly used to administer orally inhaled aerosols are the metered-dose inhaler (MDI), the small-volume nebulizer (SVN), and the dry-powder inhaler (DPI). They will be discussed in more detail in Chapter 19.

Box 18-1 Phases of Drug Action

• Drug administration phase: describes the method by which a drug dose is made available to the body

• Pharmacokinetic phase: describes the time course and disposition of a drug in the body based on its absorption, distribution, metabolism, and elimination

• Pharmacodynamic phase: describes the mechanisms of drug action by which a drug molecule causes its effects in the body

Reality Check Some facilities utilize computerized physician order entry (CPOE), which eliminates the need for written orders. Still, errors such as juxtaposition errors (choosing the wrong medication or dosage that is next on the list) could be made.

Treatment of the respiratory tract with inhaled aerosols offers many advantages such as: (1) Doses are usually smaller than doses for systemic administration, (2) the onset of drug action is rapid, (3) delivery is targeted to the organ requiring treatment, and (4) systemic side effects are often fewer and less severe.

The delivery of inhaled aerosols in treating respiratory disease also has some disadvantages, and these include (1) a number of variables affecting the delivered dose and (2) lack of adequate knowledge about device performance and use among patients and caregivers. Although other drug classes are used in respiratory care, this chapter will focus on medication administration and a review of bronchoactive inhaled aerosols.

» Skill Check Lists

18-1 Medication Administration

With RTs being responsible for the administration of numerous pulmonary medications, it may be a complex and demanding part of their daily responsibilities. Patients may be receiving several different inhaled medications during their hospital stay. Consequently, it is important to always practice safe medication administration. In the United States, The Joint Commission (TJC) accredits health care organizations, and improving patient safety must be a constant goal of the organizations. Medication safety aspects of the national patient safety goals are listed in Box 18-2.

Box 18-2 Joint Commission 2011 National Patient Safety Goals

Implications for Medication Administration

• Use at least two patient identifiers when providing care, treatment, and services.

• Improve the effectiveness of communication among caregivers.

• Improve safety in using medications.

• Accurately and completely reconcile medications across the continuum of care.

Safe medication administration begins with the six rights of medication administration:

6. Right documentation

Regardless of how you receive an order (verbal, written, protocol), you should always compare it with the medication administration record (MAR; eMAR for electronic versions) to ensure that the right medication is being administered. Many respiratory medications come in ampoules with measured doses. This does not negate the responsibility of the therapist to confirm that the right dose is being given. Concentration differences and the addition of a combination medication may result in a dose error if the RT is not careful. Two patient identifiers are mandatory before giving medication to a patient. The majority of respiratory medications are given via aerosolization. However, the order always has a designated route. The RT should assess the patient and make sure that the ordered route is the best for the patient’s current condition. The Institute for Safe Medication Practice (ISMP) compiled a list of error-prone abbreviations. Table 18-1 lists some abbreviations that are commonly misinterpreted. The right time for respiratory medications to be delivered may help the patient control his or her symptoms, as with delivery of inhaled corticosteroids, or used to relieve current complaints such as shortness of breath caused by bronchospasm.

TABLE 18-1

Institute for Safe Medication Practice List of Error-Prone Abbreviations *

Abbreviation	Intended Meaning	Misinterpretation	Correction
µg	Microgram	Mistaken as “mg”	Use “mcg”
AD, AS, AU	Right ear, left ear, each ear	Mistaken as OD, OS, OU (right eye, left eye, each eye)	Use “right ear,” “left ear,” or “each ear”
OD, OS, OU	Right eye, left eye, each eye	Mistaken as AD, AS, AU (right ear, left ear, each ear)	Use “right eye,” “left eye,” or “each eye”
BT	Bedtime	Mistaken as “BID” (twice daily)	Use “bedtime”
cc	Cubic centimeters	Mistaken as “u” (units)	Use “mL”
D/C	Discharge or discontinue	Premature discontinuation of medication if D/C (intended to mean “discharge”) has been misinterpreted as “discontinued” when followed by a list of discharge medications	Use “discharge” and “discontinue”
IJ	Injection	Mistaken as “IV” or “intrajugular”	Use “injection”
IN	Intranasal	Mistaken as “IM” or “IV”	Use “intranasal” or “NAS”
HS	Half-strength	Mistaken as bedtime	Use “half-strength”
hs	At bedtime, hour of sleep	Mistaken as half-strength	Use “bedtime”
IU**	International unit	Mistaken as IV (intravenous) or 10 (ten)	Use “units”
o.d. or OD	Once daily	Mistaken as “right eye” (OD—oculus dexter), leading to oral liquid medications administered in the eye	Use “daily”
OJ	Orange juice	Mistaken as OD or OS (right or left eye); drugs meant to be diluted in orange juice may be given in the eye	Use “orange juice”
Per os	By mouth, orally	The “os” can be mistaken as “left eye” (OS—oculus sinister)	Use “PO,” “by mouth,” or “orally”
q.d. or QD**	Every day	Mistaken as q.i.d., especially if the period after the “q” or the tail of the “q” is misunderstood as an “i”	Use “daily”
qhs	Nightly at bedtime	Mistaken as “qhr” or every hour	Use “nightly”
qn	Nightly or at bedtime	Mistaken as “qhr” or every hour	Use “nightly” or “at bedtime”
q.o.d. or QOD**	Every other day	Mistaken as q.d. (daily) or q.i.d. (4 times daily) if the “o” is poorly written	Use “every other day”
q1d	Daily	Mistaken as q.i.d. (4 times daily)	Use “daily”
q6PM, etc.	Every evening at 6 PM	Mistaken as every 6 hours	Use “6 PM nightly” or “6 PM daily”
SC, SQ, sub q	Subcutaneous	SC mistaken as SL (sublingual); SQ mistaken as “5 every”; the “q” in “sub q” has been mistaken for “every” (e.g., a heparin dose ordered “sub q 2 hours before surgery” misunderstood as every 2 hours before surgery)	Use “subcut” or “subcutaneously”
ss	Sliding scale (insulin) or (apothecary)	Mistaken as “55”	Spell out “sliding scale”; use “one-half” or “”
SSRI	Sliding scale regular insulin	Mistaken as selective-serotonin reuptake inhibitor	Spell out “sliding scale (insulin)”
SSI	Sliding scale insulin	Mistaken as Strong Solution of Iodine (Lugol’s)	Spell out “sliding scale (insulin)”
i/d	One daily	Mistaken as “tid”	Use “1 daily”
TIW or tiw	3 times a week	Mistaken as “3 times a day” or “twice a week”	Use “3 times weekly”
U or u**	Unit	Mistaken as the number 0 or 4, causing a 10-fold overdose or greater (e.g., 4U seen as 40 or 4u seen as 44); mistaken as “cc” so dose given in volume instead of units (e.g., 4u seen as 4cc)	Use “unit”