Understanding Anesthesiology - The Global Regional Anesthesia ...

• more rapid return of respiratory function, consciousness
and airway control following the completion of
the procedure
• provision of post-operative analgesia with appropriate
timing and dosing of opioids administered intraoperatively
A balanced technique is still the most common technique
used for the provision of general anesthesia.
However, with the development of short-acting intravenous
agents such as propofol and remifentanil, the
above-described goals of general anesthesia can be attained
with the use of intravenous agents alone, usually
by continuous infusion. This is called “Total Intravenous
Anesthesia” or “TIVA”.
After the patient has been assessed, the equipment and
drugs prepared and the anesthetic technique determined,
one can proceed with administering the anesthetic.
A general anesthetic consists of four phases: induction,
maintenance, emergence and recovery.
Induction
The goal of the induction phase of anesthesia is to induce
unconsciousness in a fashion which is pleasant,
rapid and maintains hemodynamic stability. If the anesthetic
plan includes control of the airway and ventilation
then the induction phase also aims to achieve muscle
relaxation to facilitate endotracheal intubation.
Anesthesia can be induced by having the patient
breathe increasing concentrations of inhaled gases by
mask. While there are settings where this is the desired
technique, it tends to be slow and can be unpleasant.
More commonly, anesthesia is induced with shortacting
intravenous agents such as propofol, ketamine,
thiopental or etomidate, followed by a muscle relaxant
if indicated. In most cases, a non-depolarizing muscle
relaxant (NDMR) is used. NDMR are discussed later in
this chapter. Understanding the dynamics of induction
requires a grasp of the essential pharmacology of these
agents; the reader can do so by touching the hyperlink
on each drug or by visiting Chapter 6.
Rapid Sequence Induction
Although regurgitation and aspiration are potential
complications of any anesthetic, there are factors which
place some patients at higher risk (Table 7). The obvious
risk factor is recent intake of solid food. However,
even a prolonged period of fasting does not guarantee
an “empty stomach” if gastric emptying is delayed. Ex-
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