Understanding Anesthesiology - The Global Regional Anesthesia ...

nal “classic” LMA including a design that facilitates
blind endotracheal intubation through the LMA (Fastrach
LMA) and one that is specially designed for use
with positive pressure ventilation with or without muscle
relaxation (Proseal LMA).
Endotracheal Intubation: There are 3 basic indications
for intubation:
1. To provide a patent airway. An endotracheal tube
(ETT) may be necessary to provide a patent airway
as a result of either patient or surgical factors (or
both). For example, an ETT is required to provide a
patent airway when surgery involves the oral cavity
(e.g. tonsillectomy, dental surgery). An ETT provides
a patent airway when the patient must be in the
prone position for spinal surgery. Airway pathology
such as tumour or trauma may compromise patency,
necessitating an ETT.
2. To protect the airway. Many factors predispose a patient
to aspiration. (Read more about risk of aspiration.)
A cuffed endotracheal tube, although not 100%
reliable, is the best way to protect the airway of an
anesthetized patient.
3. To facilitate positive pressure ventilation. Some surgical
procedures, by their very nature, require that
the patient be mechanically ventilated which is most
effectively and safely achieved via an ETT. Mechanical
ventilation is required when:
• the surgery requires muscle relaxation (abdominal
surgery, neurosurgery).
• the surgery is of long duration such that respiratory
muscles would become fatigued under anesthesia.
• the surgery involves the thoracic cavity.
In rare cases, an ETT may be required to improve oxygenation
in patients with critical pulmonary disease
such as Acute Respiratory Distress Syndrome (ARDS),
where 100% oxygen and positive end expiratory pressure
(PEEP) may be needed.
While intubation is most commonly performed orally,
in some settings nasotracheal intubation is preferable
such as during intra-oral surgery or when long-term intubation
is required. Nasotracheal intubation may be
accomplished in a blind fashion (i.e. without performing
laryngoscopy) in the emergency setting if the patient
is breathing spontaneously.
Nasotracheal intubation is contraindicated in patients
with coagulopathy, intranasal abnormalities, sinusitis,
extensive facial fractures or basal skull fractures.
While there are myriad devices and techniques used to
achieve intubation (oral or nasal), most often it is performed
under direct vision using a laryngoscope to ex-
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