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Pharmacotherapy for Mechanical Ventilation 451

reactions (EPS) and may include unilateral cervical muscle contraction with neck
Neck twisting, swollen twisting (torticollis), swollen tongue (laryngeal dystonia), jaw muscle spasm (tris-
tongue, jaw muscle spasm,
and flexion of head and feet mus), and flexion of head and feet backward (opisthotonus) (McEvoy, 1995). EPS
backward are some adverse occurs much less frequently with IV haloperidol than that observed with intramus-
effects of haloperidol.
cular or oral therapy. The reason for this is currently unknown (Fish, 1991).
Neuroleptic malignant syndrome is a rare, idiosyncratic, life-threatening reaction
that may occur after a single dose of haloperidol. Hyperthermia, altered conscious-
ness, labile blood pressure, diaphoresis, and tachyarrhythmias are suggestive of this
condition (Simon, 1993).
Haloperidol may also prolong the electrocardiographic QT interval that on rare
occasions can produce a polymorphic form of ventricular tachycardia known as
torsade de pointes (Fish, 1991).

Clinical Considerations. Combination therapy including a benzodiazepine, opioid, and
Combined use of a haloperidol is often necessary for control of extremely agitated, delirious patients
benzodiazepine, opioid, and
haloperidol is often necessary requiring critical care. The critical care team must be diligent in the search for revers-
for control of extremely ible causes of delirium and, if found, must correct them whenever possible.
agitated, delirious patients.
Dexmedetomidine

For decades, gamma-aminobutyric acid (GABA) receptor agonists (e.g., propofol,
midazolam) have been used extensively as a sedative of choice in the intensive care
units (Riker et al., 2009). Dexmedetomidine (Precedex) is a newer intravenous
dexmedetomidine (Precedex):
An intravenous drug that offers drug (since 1999 in the U.S.) that offers anxiolysis and analgesia but no respiratory
anxiolysis and analgesia but no depression (Bekker et al., 2005). The lack of respiratory depression is desirable for
respiratory depression.
the management of mechanically ventilated patients, especially during measure-
ment of weaning mechanics and evaluation of weaning feasibility.
Indications. Dexmedetomidine is indicated for sedation in mechanically ventilated
patients. It can be used as a continuous infusion prior to extubation, during extu-
bation, and postextubation. It is not necessary to discontinue dexmedetomidine
prior to extubation. Dexmedetomidine is also used for sedation of patients prior to
and during cardiac or vascular surgeries or other uncomfortable procedures such
as colonoscopy (Precedex, 2012). Intranasal dexemedetomidine is another route of
administration for children undergoing MRI and CT procedures. Since this drug
has a neutral pH, it is painless when given intranasally (Phillips, 2010).
Mechanism of Action. Dexmedetomidine is an a adrenoreceptor agonist with a
2
Dexmedetomidine unique combination of physiologic actions. It provides sedation and anxiolysis via
(Precedex) provides sedation
and anxiolysis via receptors receptors within the locus ceruleus (group of neurons in the pons), analgesia via
within the locus ceruleus, receptors in the spinal cord, and gradual reduction of stress response with no sig-
analgesia via receptors in
the spinal cord, and gradual nificant respiratory depression (Riker et al., 2009).
reduction of stress response
with no significant respiratory Adverse Effects. Dexmedetomidine should be administered using a dosage-controlled
depression.
infusion device, and the manufacturer recommends a duration of infusion not to
exceed 24 hours. However, randomized clinical trials comparing the drug to mid-
azolam and lorazepam have demonstrated efficacy and safety for up to 5 days of con-
tinuous use (Riker et al., 2009). Because dexmedetomidine decreases sympathetic

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