Page 457 - Clinical Application of Mechanical Ventilation

Pharmacotherapy for Mechanical Ventilation 423

Stimulants
(Phenylephrine)
Alpha-1
Inhibitors-Nonspecific
(Phentolamine)
Alpha-2
Stimulants (Clonidine)

Sympathetic
Pathway *Primarily Beta-1,
(Adrenergic Mild Beta-2
Receptors) Beta-1
Inhibitors
(Esmolol, Atenolol)

Inhibitors
(Experimental Use Only)
Autonomic Nervous
System Agents Beta-2
Stimulants
(Albuterol, Formoterol)
Commonly Used for
Bronchodilator Effect

Inhibitors – Anticholinergic
(Ipratropium, Tiotropium)
Parasympathetic Pathway
(Cholinergic Receptors) © Cengage Learning 2014
Stimulants – Cholinergic
(Methacholine)
Figure 13-1 Examples of drugs that exert their effects on the sympathetic and parasympa-
thetic pathways under the autonomic nervous system.

Bronchodilation can be achieved by eliciting an adrenergic response (sympathomi-
metic action) or by interfering with the cholinergic response (parasympatholytic ac-
tion). Many bronchodilators use the sympathomimetic action (sympathomimetic
sympathomimetic broncho-
dilators: Adrenergic agonists. bronchodilators) while other bronchodilators take advantage of the parasympa-
Drugs that dilate the airways by tholytic action (parasympatholytic bronchodilators). Table 13-1 shows these two
stimulating the beta-2 receptors
of the sympathetic nervous pathways to achieve bronchodilation.
system. Examples are epineph-
rine (Adrenaline) and albuterol
(Ventolin, Proventil). Adrenergic Bronchodilators (Sympathomimetics)

Adrenergic bronchodilators are agents that stimulate the adrenergic receptors via
parasympatholytic bron-
chodilators: Anticholinergic the sympathetic nerve fibers of the autonomic nervous system.
bronchodilators. Drugs that
dilate the airways by inhibiting Mechanism of Action. Sympathetic adrenergic receptors are distributed throughout
the parasympathetic branch of
the autonomic nervous system. the body. They are identified and classified according to their response to specific
Examples are atropine and ipratro- neurotransmitter substances. Alpha 1, alpha 2, beta 1, and beta 2 are the types that
pium bromide (Atrovent).
have been identified. Some important effects associated with these receptors are
shown in Table 13-2.

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