Understanding Anesthesiology - The Global Regional Anesthesia ...

arely actively reversed in order to achieve emergence.
There is no “antidote” to the inhaled agents; offset of
effect relies on the timely discontinuation of administration
followed by excretion through the lungs. While an
opioid antagonist (naloxone) exists, there are several
disadvantages to using it to reverse opioid effect at the
end of surgery. Firstly, unless very carefully titrated, its
use will lead to a startled, hyper-alert patient who complains
of pain at the operative site. Hypertension, tachycardia,
myocardial ischemia and pulmonary edema
may result. Secondly, the duration of effect of the antagonist
is shorter than that of many of the opioid agonists
therefore “re-narcotization” in the PACU is a risk.
Finally, naloxone is an expensive drug whose use adds
unnecessarily to the cost of the anesthetic. Flumazenil
is a specific benzodiazepine antagonist which may play
a role in the occasional surgical patient whose decreased
level of consciousness is attributed to benzodiazepines.
Like naloxone, flumazenil has a shorter duration
of action than most of the benzodiazepine agonists
therefore rebound sedation may occur.
Extubation
If an endotracheal tube is used to maintain the airway
intra-operatively, it must be removed at some point during
the emergence phase of anesthesia. It is important
to time the extubation properly, so as to avoid the potential
post-extubation complications:
• airway obstruction
• aspiration
• inadequate ventilation
• laryngospasm
If the patient meets three simple criteria, most emergence
complications can be avoided. The anesthesiologist
must ensure that:
• the patient has regained their drive to breathe. Sufficient
offset of effect of opioids is required for the patient
to resume and maintain spontaneous respiration.
• the patient has normal muscle strength. A “weak” patient
will not have enough strength to keep the
tongue from falling to the back of the pharynx and
causing airway obstruction. Muscle strength is also
required to achieve satisfactory tidal volumes. Adequate
muscle strength is required for the cough reflex
which protects the airway from aspiration.
• the patient is awake enough to obey commands. An
adequate level of consciousness is required in order
for the patient to protect his airway from aspiration
and to avoid laryngospasm.
Laryngospasm (reflexive closure of the vocal cords) deserves
special mention. Laryngospasm is the airway’s
response to irritation. It can occur immediately after ex-
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