Page 125 - Clinical Application of Mechanical Ventilation

Operating Modes of Mechanical Ventilation 91

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Figure 4-3 Continuous positive airway pressure (CPAP) of 10 cm H 2 O. © Cengage Learning 2014

CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP)

Continuous positive airway pressure (CPAP) is PEEP applied to the airway
of a patient who is breathing spontaneously (Figure 4-3). The indications for
CPAP are essentially the same as for PEEP with the additional requirement
eucapnic ventilation: The that the patient must have adequate lung functions that can sustain eucapnic
amount of ventilation needed ventilation documented by the PaCO . In adults, CPAP may be given via a
to bring the patient’s PaCO 2 to 2
normal. face mask, nasal mask, or endotracheal tube. In neonates, nasal CPAP is the
method of choice.

BILEVEL POSITIVE AIRWAY PRESSURE (BiPAP)

bilevel positive airway pres- Bilevel positive airway pressure (BiPAP) allows the clinician to apply independent
sure (BiPAP): An airway pressure positive airway pressures to both inspiration and expiration. IPAP (inspiratory) and
strategy that applies independent
positive airway pressures (PAP) to EPAP (expiratory) are used to define when the positive airway pressure is present.
both inspiration and expiration.
IPAP provides positive pressure breaths, and it improves ventilation and hypox-
emia due to hypoventilation. EPAP is in essence CPAP, and it improves oxygen-
ation by increasing the functional residual capacity and reducing intrapulmonary
shunting.

Indications for BiPAP

BiPAP appears to be of value in preventing intubation of the end-stage COPD pa-
BiPAP appears to be of tient (Ambrosino et al., 1992; Confalonieri et al., 1994; Renston et al., 1994) and in
value in preventing intubation
of the end-stage COPD patient supporting patients with chronic ventilatory failure (Strumpf, 1990). Other indica-
and in supporting patients tions of BiPAP include patients with restrictive chest wall disease (Hill, 1992), neu-
with chronic ventilatory
failure. romuscular disease (Ellis et al., 1987), and nocturnal hypoventilation (Carroll et al.,
1988; Waldhorn, 1992). See Chapter 7, “Noninvasive Positive Pressure Ventilation.”

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