2-21. ENDOTRACHEAL INTUBATION
a. An endotracheal tube may be inserted through the nose or mouth into the
trachea. This procedure is normally done by a physician or a nurse anesthetist.
Endotracheal intubation may be done during surgery to facilitate anesthesia and control
respirations, to bypass an upper airway obstruction, or to permit connection of the
b. Endotrachial (ET) tubes generally have an inflatable cuff, which holds the
tube in place in the trachea and prevents aspiration of upper respiratory tract secretions
into the lower respiratory tract. The cuff must be deflated periodically to prevent injury
to the trachea.
c. If intubation is necessary for an extended period of time, a tracheotomy is
performed and the patient is intubated with a tracheostomy tube. This surgical
procedure will be discussed in section VI.
2-22. MECHANICAL VENTILATION
a. When a patient is unable to maintain appropriate levels of arterial oxygen and
carbon dioxide by normal breathing, some sort of mechanical assistance becomes
necessary. A mechanical ventilator is a positive pressure-breathing device that
maintains respirations automatically. Ventilators may be used for complete or partial
control of a patient's respirations.
b. Mechanical ventilators are used in three modes of operation: assist, control,
and assist-control. Determination is made by the physician according to the needs of
(1) Control mode is used for the patient whose respiratory drive is absent or
excessive. The ventilator initiates breathes at a pre-set rate and will not respond to any
patient attempts to initiate a breath.
(2) Assist mode is used for the patient who is able to make an inspiratory
effort, but is unable to inhale an adequate amount of air. The patient initiates each
breath and the ventilator then augments the breath to achieve a preset volume of air.
(3) Assist-control mode is used for the patient who has an erratic respiratory
pattern. The ventilator will function in assist mode as long as the patient maintains an
adequate respiratory rate. If the patient's respiratory rate falls below a preset level, the
machine will switch to control mode and initiate breaths. The ventilator will switch from
assist to control as determined by the needs of the patient.
c. The ventilator settings are determined by the physician.
Tidal volume--The amount of air delivered for each inhalation.