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Pharmacotherapy for Mechanical Ventilation 429

The end result for these individuals is higher maintenance theophylline dosages to
maintain bronchodilation (Cottrell et al., 1995).

Anti-Inflammatory Agents (Corticosteroids)

In addition to the drugs that exert their bronchodilation effects using the pathways
corticosteroids: Hormones that in the autonomic nervous system, corticosteroids are a different group of drugs that
are released from the cortex of are useful in the management of bronchoconstriction and airflow obstruction due to
the adrenal gland. Their potent
anti-inflammatory effects make airway inflammation. Corticosteroids are powerful, naturally occurring hormones
corticosteroids useful in the treat-
ment of asthma and chronic bron- that are released from the adrenal cortex. Their anti-inflammatory effects make them
chitis. Corticosteroids are available first-line drugs in the management of chronic asthma and other long-term airway
for intravenous administration as
well as inhalation. Examples of inflammatory conditions. In the intensive care setting, they have been used with
inhaled steroids are dexametha- favorable results in status asthmaticus, acute exacerbation of COPD, inhalation air-
sone (Decadron, Respihaler),
beclomethasone (Beclovent, way injury, drug-induced pneumonitis, septic shock, ARDS, and spinal cord injury.
Vanceril), flunisolide (AeroBid), Corticosteroids have no bronchodilator effect and should not be given alone during
and triamcinolone (Azmacort).
an acute asthma attack. The effects of corticosteroids require an onset time of about
2 to 24 hours, further demonstrating their inappropriateness in acute situations.
Mechanism of Action. The general functions of corticosteroids include (1) carbohy-
drate metabolism, (2) immunosuppression, and (3) reduced inflammation. Their
specific mechanism in reducing inflammation is complex, involving genetic changes
to target cells of inflammation. The combination of the steroid with its receptor site
(nucleus of target cell) results in altered cellular function.
Normally, an inflammatory response results in the release of histamine and bra-
Corticosteroids return dykinin (among other mediators) from the mast cell, causing bronchoconstriction
constricted airways to normal
by blocking the inflammatory and increased capillary permeability. This leads to early-phase bronchoconstriction
mediators. and late-phase submucosal edema and hyperactivity (Gardenhire, 2007). With al-
tered cellular function, these and other mediators are blocked and inflammation is
reduced.
Adverse Effects. Corticosteroids are available for oral, intravenous, and inhalation
administration (Tables 13-6 and 13-7), and, as with most agents, the inhalation
route is favored for its convenience, smaller dosage, and fewer adverse effects.
The most frequent adverse effects reported with a metered-dose inhaler (MDI)
use are hoarseness and oral fungal infections (e.g., candidiasis). To prevent fungal

TABLE 13-6 Corticosteroids for Metered-Dose Inhaler (MDI) Use

Drug MDI Dosage Frequency
Beclomethasone (QVAR) 2 puffs 2 times/day

Flunisolide (AeroBid) 2 puffs 2 times/day

Triamcinolone (Azmacort) 2 puffs 3 to 4 times/day
Fluticasone propionate (Flovent) 2 puffs 2 times/day
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