Neuroleptanalgesia-Anesthesia
In 1949, Laborit and Huygenard introduced the concept of an anesthetic
technique that blocked not only cerebrocortical responses but also some cellular,
endocrine, and autonomic mechanisms usually activated by surgical stimulation. This
state was called "ganglioplegia" or "neuroplegia" (artificial hibernation) and was
achieved by the use of a "lytic cocktail" consisting of chlorpromazine, promethazine,
and meperidine. From this idea, in 1959, De Castro and Mundeleer derived the concept
of neuroleptanalgesia, which involved the combination of a major transquilizer (usually
the butyrophenone droperidol) and a potent opioid analgesic (fentanyl) to produce
a detached, pain-free state of immobilization and insensitivity to pain. Neuroleptanalgesia
is characterized by analgesia, suppression of motor activity, suppression of autonomic
reflexes, maintenance of cardiovascular stability, and amnesia in most patients.
The addition of an inhaled agent, usually N2
O, improves amnesia and has
been called neuroleptanesthesia.
"Neuroleptic" drugs traditionally include the phenothiazines (e.g.,
chlorpromazine) and the butyrophenones (e.g., haloperidol and droperidol). Butyrophenones
cause sedation, transquility, immobility, antiemesis, an extrapyramidal syndrome
with face and neck dyskinesia, oculogyric crises, torticollis, agitation, and hallucinations.
Administering droperidol alone, without analgesics or other sedatives, often produces
feelings of discomfort or dysphoria in patients. The cardiovascular effects of droperidol
are
most often limited to mild hypotension that is thought to be mediated through α-adrenergic
blockade. There is little respiratory depression induced by droperidol, although
significant variability exists, and occasional respiratory depression may be noted.
Droperidol and other butyrophenones may enhance hypoxia-induced increases in ventilation
in humans because of their antidopaminergic effects at the carotid body. Droperidol
can be used as a premedicant (0.025–0.075 mg/kg IM), an antiemetic (0.01–0.02
mg/kg IV), an adjunct for awake intubations (0.025–0.1 mg/kg IV) and treatment
for agitated, belligerent, or psychotic patients (0.05–0.2 mg/kg IV or IM).
Neuroleptanalgesia or neuroleptanesthesia is contraindicated in patients receiving
monoamine oxidase inhibitors (MAOIs), in those who abuse drugs or alcohol, or those
with Parkinson's disease.
