Page 432 - Clinical Application of Mechanical Ventilation

398 Chapter 12

Other conditions that can affect the patency of the ET tube include (1) kinking
or bending of the tube due to poor positioning of the patient and placement of the
ventilator circuit; (2) patient biting on the ET tube due to physical or psychologic
discomfort; and (3) malfunction of the ET tube cuff causing partial or complete
blockage.
Frequent endotracheal suctioning is sometimes necessary to maintain the patency
of the endotracheal tube. One of the problems with endotracheal suctioning is
hypoxia. Suction-induced hypoxia may be minimized by preoxygenating the pa-
tient prior to suction, limiting the total suction time to no more than 10 sec, and
using a closed inline tracheal suction system (Wilkins et al., 2003). Since the closed
Since the closed suction- suctioning system allows suctioning without disconnecting the ventilator circuit,
ing system allows suctioning
without disconnecting the F O and PEEP levels may be maintained. Closed inline suction catheters may be
I
2
ventilator circuit, F I O 2 and PEEP changed weekly (instead of daily) with no significant increase in the frequency of
levels may be maintained.
ventilator-associated pneumonia (Stoller et al., 2003). Figure 12-6 shows a closed
tracheal suction system.
Humidification and Removal of Secretions

Proper function of the ciliary blanket of the airway is dependent on adequate
humidity. In mechanical ventilation, humidification is commonly provided by a
heated humidifier, heated wire circuit, or, for short-term use, a heat and moisture
exchanger (HME, or artificial nose). Occasionally, humidification and removal of
the secretions are supplemented by use of a saline solution or mucolytic agent via a
small volume nebulizer. Instilling a saline solution directly into the airway for the
Instilling a saline solution purpose of thinning the secretions or stimulating a cough is not supported by the
directly into the airway for the
purpose of thinning the secre- literature (Branson, 2007).
tions or stimulating a cough is
not supported by the literature Saline solution used in a small volume nebulizer is delivered in an aerosol form,
(Branson, 2007). and is capable of carrying pathogens into the lower airways. Instillation of saline
solution directly into the trachea to facilitate endotracheal suctioning has also been
implicated in the contamination of the lower airways with pathogens (Hagler et al.,
1994). For these reasons, aseptic techniques for equipment handling and sterile
techniques for endotracheal suctioning must be followed in order to minimize the
occurrence of pulmonary contamination and ventilator-associated pneumonia (Sole
et al., 2003).

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Figure 12-6 An example of a closed suction system manufactured by Ballard Medical, Inc.

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