Understanding Anesthesiology - The Global Regional Anesthesia ...

amples of conditions which impair gastric emptying include
diabetes, trauma, recent opioid administration
and bowel obstruction. Finally, decreased integrity of
the lower esophageal sphincter, as occurs in pregnancy
and obesity, increases the risk of regurgitation of stomach
contents. In patients deemed to be at increased risk
for aspiration, the time between inducing anesthesia
and securing the airway with a cuffed endotracheal
tube must be minimized. Such a technique is termed a
“rapid sequence induction”.
A rapid sequence induction is performed as follows:
1. Suction apparatus is checked and kept readily available.
2. Pre-oxygenation of patient with 100% oxygen for 3-5
minutes.
3. Application of cricoid pressure (Sellick’s maneuver)
by assistant.
4. Induction with pre-calculated dose of induction
agent followed immediately by intubating dose of
depolarizing muscle relaxant (succinylcholine). A
rapidly acting non-depolarizing agent (e.g. rocuronium)
is commonly used in a so-called “modified”
rapid sequence induction.
5. Intubation of trachea, cuff inflation and verification
of proper tube position.
The purpose of pre-oxygenation is to lessen the risk of
hypoxemia occurring during the apneic period after induction.
Although pre-oxygenation does increase the
patient’s arterial PO2 prior to induction, its most important
effect is the de-nitrogenation of the functional residual
capacity of the lungs. Traditionally teaching is
that the Sellick maneuver provides occlusion of the
esophagus between the cricoid cartilage (a complete circumferential
cartilage) and the cervical vertebrae thus
minimizing the risk of passive regurgitation.
Succinylcholine
Succinylcholine (Sch), a depolarizing muscle relaxant,
is a very useful and very powerful drug; the anesthesiologist
must understand the effects and contraindications
of Sch in order to avoid causing harm or death.
Succinylcholine causes rapid, profound and brief muscular
paralysis. It acts by attaching to nicotinic cholinergic
receptors at the neuromuscular junction. There, it
mimics the action of acetylcholine, thus depolarizing
the post-junctional membrane. Neuromuscular blockade
(paralysis) develops because a depolarized postjunctional
membrane cannot respond to subsequent release
of acetylcholine.
Succinylcholine has effects on almost every organ system,
most of them being secondary to the depolarization
and subsequent contraction of skeletal muscle.
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