page_title: High-frequency ventilation
section_title: Bunnell LifePulse jet ventilator
hierarchical_section_title: High-frequency ventilation / High-frequency jet ventilation (passive) / Bunnell LifePulse jet ventilator
caption_attribution_description: English: Bidirectional Flow During HFJV
context_page_description: High-frequency ventilation is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value. and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury, especially in the context of ARDS and acute lung injury. This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.
  High-frequency ventilation may be used alone, or in combination with conventional mechanical ventilation. In general, those devices that need conventional mechanical ventilation do not produce the same lung protective effects as those that can operate without tidal breathing. Specifications and capabilities will vary depending on the device manufacturer.
context_section_description: High-frequency jet ventilation (HFJV) is provided by the Bunnell Life Pulse High-Frequency Ventilator.  HFJV employs an endotracheal tube adaptor in place for the normal 15 mm ET tube adaptor. A high pressure "jet" of gas flows out of the adaptor and into the airway. This jet of gas occurs for a very brief duration, about 0.02 seconds, and at high-frequency: 4-11 hertz. Tidal volumes ≤ 1 ml/Kg are used during HFJV. This combination of small tidal volumes delivered for very short periods of time creates the lowest possible distal airway and alveolar pressures produced by a mechanical ventilator. Exhalation is passive. Jet ventilators utilize various I:E ratios—between 1:1.1 and 1:12—to help achieve optimal exhalation. Conventional mechanical breaths are sometimes used to aid in reinflating the lung. Optimal PEEP is used to maintain alveolar inflation and promote ventilation-to-perfusion matching. Jet ventilation has been shown to reduce ventilator induced lung injury by as much as 20%.  Usage of high-frequency jet ventilation is recommended in neonates and adults with severe lung injury.
caption: Bidirectional Flow During HFJV
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