Understanding Anesthesiology - The Global Regional Anesthesia ...

Important effects include increased intracranial pressure,
increased intragastric pressure and post-operative
myalgia.
The most critical effects of Sch relate to its interaction
with muscle cells. Sch elevates serum potassium by 0.5
mEq/L in patients with normal neuromuscular function
and is therefore contraindicated in hyperkalemic patients
or in patients with renal failure, for whom even a small
rise in potassium could have critical implications. Sch
can cause an exaggerated release of potassium, leading
to fatal hyperkalemia, in those with neuromuscular or
muscle disease. Examples include recent paralysis (spinal
cord injury or stroke), amyotrophic lateral sclerosis,
Duchenne’s muscular dystrophy and recent burn or
crush injury.
Sch is a potent trigger of malignant hyperthermia (MH)
and is therefore contraindicated in MH-susceptible patients.
Sch is contraindicated in patients with pseudocholinesterase
deficiency in whom the paralysis will
be prolonged.
A more complete discussion of succinylcholine can be
found in Chapter 6.
Maintenance
If no further agents were administered following the
induction of anesthesia the patient would awaken
within minutes. Therefore, maintenance of anesthesia
requires the delivery of pharmacologic agents with the
aim of achieving the “four A’s of anesthesia” and hemodynamic
stability throughout the surgical procedure. A
further consideration is the length of the procedure and
the need to awaken the patient at the end of the case.
The maintenance phase of anesthesia involves the use
of inhaled agents, opioids and non-depolarizing muscle
relaxants (NDMR). These agents are described later
in this chapter.
The anesthesiologist must be ever vigilant. Problems
related to the airway, breathing and circulation (ABC’s)
are most critical and can occur during any phase of anesthesia.
Several of the problems that are unique to the
maintenance phase of anesthesia are discussed below.
Awareness
“Awareness” refers to a complication of anesthesia
whereby a patient who has received a general anesthetic
becomes conscious of his or her environment during
the surgical procedure. The patient may or may not
experience pain and may or may not recall the events
post-operatively. The incidence of awareness with recall
has been estimated at 0.2-1.0%. Some types of surgical
procedures such as Caesarian section, cardiac surgery
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