Page 622 - Clinical Application of Mechanical Ventilation

588 Chapter 18

Types of Ventilatory Support. If the patient does not have adequate spontaneous ven-
tilation for an extended time, positive pressure or negative pressure ventilators are
the equipment of choice. Positive pressure ventilation requires an artificial airway,
whereas negative pressure ventilation can be provided without an artificial airway.
One exception to this practice is the presence of significant airway obstruction.
A backup ventilator may be necessary if the patient is totally dependent on me-
A backup ventilator may chanical ventilation. For patients who are using mechanical ventilation on a part-
be necessary if the patient
is totally dependent on time basis (e.g., during sleep), a backup system may not be needed or may not be
mechanical ventilation. financially justifiable.
Other methods of providing ventilatory support include the chest cuirass, raincoat
or wrap, pneumobelt, rocking bed, and diaphragmatic pacing. A chest cuirass ventila-
tor is a shell that fits over the patient’s chest wall (Figure 18-1). The raincoat or wrap is
Other methods of an airtight jacket that seals at the arms, hips, and neck. It covers a larger area than the
providing ventilatory support
include the chest cuirass, chest cuirass and does not impinge on the chest and abdomen. For this reason, it offers
raincoat or wrap, pneumobelt, a larger inspiratory volume to the user. The raincoat or wrap is more difficult to get
rocking bed, and diaphrag-
matic pacing. into and usually requires help from another person in the home. The pneumobelt is a
corsetlike belt attached to a positive pressure generator. The positive pressure inflates
the belt, squeezes the abdomen, and pushes the diaphragm upward. An alternating se-
quence of positive pressure and ambient pressure provided to the pneumobelt produces
ventilation. The rocking bed relies on motion to displace the abdominal contents to
facilitate diaphragmatic motion and ventilation (Hill, 1994; Votroubek, 1995).

Diaphragmatic Pacing. Diaphragmatic pacing or bilateral pacing of the phrenic
nerves does not actually provide mechanical ventilation. Rather, it is used to aug-
ment spontaneous ventilation. Diaphragmatic pacing has been used in infants and
children for more than a decade (Ilbawi et al., 1985). The pacing system includes
an external transmitter and antenna placed on the skin over a receiver implanted
subcutaneously. At a predetermined interval, the receiver sends electrical energy to
an electrode placed near the thoracic phrenic nerves. When the phrenic nerves are
stimulated by electrical energy, the diaphragm contracts (Votroubek, 1995).

Courtesy of Post-Polio Health International

Figure 18-1 Chest cuirass in use by a man following the polio epidemic in the 1950’s.

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.