The clinical benefits of APRV include the preservation of spontaneous breathing and comfort with most spontaneous breathing occurring at high CPAP but it can occur throughout the ventilatory cycle with little work of breathing being imposed by the ventilator. In BiPAP the circuit switches between a high and low airway pressure in an adjustable time sequence. If the patient is not breathing spontaneously, this mechanical volume displacement is taken as a pressure controlled mechanical ventilation. The mandatory breaths are pressure controlled and the spontaneous breaths can be pressure supported. In BiLevel the ventilator cycling between the two pressure levels can be synchronized with the patient to prevent a cycle to low pressure just as a patient takes a breath.
Spontaneous breaths can be pressure supported at the high and low pressure levels.
The advantages of this method of ventilation are the decreased level of sedation required to facilitate patient acceptance of the ventilator and the concept of a single modality to ventilate the patient. BiLevel can offer full ventilatory support and can then be weaned off, as the patient ventilatory needs resolve. High Frequency Ventilation High Frequency Ventilation can be either jet ventilation or oscillation. Air or supplementary O2 is entrained with the jetted ventilatory breath and expiration is purely passive. Another situation where it may come in handy is when you are treating a disrupted airway or massive bronchopleural fistula as the non bulk flow of gas decreases the amount of gas escaping out of the fistula.