Page 231 - Clinical Application of Mechanical Ventilation

Noninvasive Positive Pressure Ventilation 197

sudden cardiovascular death, and increased risk for brain infarction (Kyzer &
Charuzi, 1998).
Treatments for OSA include oral applications such as prosthetic mandibular
advancement (Ishida et al., 1998; Millman, Rosenberg & Kramer, 1998), surgi-
cal interventions such as tonsillectomy and uvulopalatopharyngoplasty for upper
obstructions (Miyazaki, Itasaka & Tada et al., 1998; Powell, Riley & Robinson,
1998), and weight reduction gastric surgery for morbidly obese patients (Kyzer &
Charuzi, 1998). Conservative therapies such as weight loss and patient positioning
have been disappointing. CPAP has become the treatment of choice for the vast
majority of patients with moderate to severe OSA (Henderson & Strollo, 1999;
Rosenthal et al., 1998; Wilkins & Dexter, 1998). The procedure to titrate CPAP
level is discussed later in this chapter.

USE Of BIlEVEl POSITIVE AIRwAy PRESSURE

(BIlEVEl PAP)

Bilevel positive airway pressure (bilevel PAP) differs from CPAP in that bilevel
bilevel positive airway pres-
sure (bilevel PAP): Bilevel PAP PAP has two pressure levels, whereas CPAP has only one. Bilevel PAP has an in-
has two pressure levels, whereas spiratory positive airway pressure (IPAP) setting that provides mechanical breaths
CPAP has only one.
and an expiratory positive airway pressure (EPAP) level that functions as positive
end-expiratory pressure (PEEP). When bilevel PAP is used as an adjunct to pro-
vide mechanical ventilation, the two major indications are acute respiratory failure
positive end-expiratory
pressure (PEEP): An airway (Aboussouan, 2010; Abou-Shala, 1996; Jasmer, 1997; Keenan, 1997; Kramer et al.,
pressure that is above 0 cm H 2 O at 1995; Wysocki et al., 1995) and acute hypercapnic exacerbations of COPD (Diaz
end-expiration.
et al., 1997; Girault et al., 1997). The most common criteria for the determination
of acute respiratory failure are blood gas results. Typical results may show par-
tially compensated respiratory acidosis with moderate hypoxemia (e.g., pH ,7.35,
Two indications for bi-
2
level PAP are acute respiratory PaCO . 50 mm Hg, PO , 55 mm Hg). For patients with hypoxemic respiratory
2
failure and acute hypercapnic failure, refractory hypoxemia may be present in addition to increasing PCO . A
exacerbations of COPD. 2
PaO /F O (P/F) index of less than 250 mm Hg suggests presence of refractory hy-
2
I
2
poxemia (PaO does not respond to high F O ). In patients with acute cardiogenic
2
2
I
pulmonary edema, CPAP or bilevel PAP ventilation has been found to reduce the
need for subsequent mechanical ventilation (Peter et al., 2006).
Patients who are unable to use or tolerate a nasal or oronasal mask are not can-
didates for NPPV (e.g., facial trauma, claustrophobia, mouth breather, and lack
of teeth). These patients may try a full-face mask. Inability to protect the airway
from secretions or aspirations is also a contraindication for NPPV. NPPV should
not be used in apneic patients. For apneic patients, traditional mechanical ventila-
tion is indicated. Furthermore, patients who have acute respiratory distress should
not be treated with NPPV, as this strategy may delay endotracheal intubation and
initiation of mechanical ventilation. Delay to implement mechanical ventilation
may lead to poor patient outcome (Wood et al., 1998). Table 7-3 outlines the com-
mon indications and contraindications for NPPV.

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.