Page 208 - Clinical Application of Mechanical Ventilation

174 Chapter 6

Secretions must be removed by way of ET suctioning. However, frequent and
inappropriate ET suctioning can cause mucosal damage and increase the inci-
dence of suction-induced hypoxemia and arrhythmias. Therefore, ET suctioning
should not be done on a preset sechedule; it should be done only when indicated.
The size of a suction catheter should be large enough for removal of secretions.
However, an oversized suction catheter may impede airflow through the ET
tube. As a rule of thumb, the outside diameter of the suction catheter should
not exceed 50% of the inside diameter of the ET tube (Wilkins et al., 2003).
The appropriate suction For example, a size 12 Fr suction catheter should be used to suction a size
catheter size in French (Fr)
may be estimated by multiply- 8 ET tube. The equation is (8 mm 3 3)/2. The 3 in the equation is the factor
ing the ET tube size by 3, and to convert mm to Fr. The 2 in the equation is to obtain 50% of the ET tube
then dividing by 2. The equa-
tion is Fr 5 (mm 3 3) / 2. diameter. If the calculate size is not available, the next larger suction catheter
may be used.
The level of vacuum pressure should be kept between 70 and 150 mm Hg for
adults and lower for infants and children (Figure 6-18). The effectiveness of suction
(based on the amount of secretion removed) is optimal at a vacuum pressure of
100 mm Hg. Pressures higher than 100 mm Hg are not more effective but more
likely to cause damage to the tracheal wall (Hahn, 2010).
Suction-induced hypoxemia may be avoided by preoxygenating the patient with
To avoid suction-induced 100% oxygen and limiting the duration of suctioning from 10 to 15 sec for adults and
hypoxemia, preoxygenate the
patient and keep the duration up to 5 sec for pediatric patients (Hahn, 2010). A closed in-line suction system (e.g.,
of suction to less than 15 sec. Ballard) may be useful to suction patients who have copious amounts of secretions. This
system allows suctioning without the need to disconnect the ventilator circuit. Since it
is a closed system, the PEEP level as well as other ventilation and oxygenation settings
on the ventilator may be maintained throughout the suctioning period (Rodenhizer,
2004). As an added financial benefit over the traditional disposable suction catheters,
the in-line suction system does not require frequent changes (Kollef et al., 1997).

© Cengage Learning 2014

Figure 6-18 A Puritan-Bennett suction regulator with vacuum pressures ranging from 0 to
200 mm Hg.

Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.