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Friday, December 17, 2010

Critical Care | Full text | Clinical review: Biphasic positive airway pressure and airway pressure release ventilation

Critical Care | Full text | Clinical review: Biphasic positive airway pressure and airway pressure release ventilationAPRV and BiPAP ventilate by time-cycled switching between two pressure levels in a high flow or demand valve continuous positive airway pressure (CPAP) circuit, and therefore they allow unrestricted spontaneous breathing in any phase of the mechanical ventilator cycle [4,5]. The degree of ventilatory support is determined by the duration of both CPAP levels and Vduring APRV/BiPAP [4,5]. Vdepends mainly on respiratory compliance and the difference between the CPAP levels. BiPAP is identical to APRV except that no restrictions are imposed on the duration of the low CPAP level (release pressure) [5]. Based on the initial description, APRV uses a duration of low CPAP (release time) that is equal to or less than 1.5 s.