High frequency ventilation

Jump to navigation Jump to search

WikiDoc Resources for High frequency ventilation

Articles

Most recent articles on High frequency ventilation

Most cited articles on High frequency ventilation

Review articles on High frequency ventilation

Articles on High frequency ventilation in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on High frequency ventilation

Images of High frequency ventilation

Photos of High frequency ventilation

Podcasts & MP3s on High frequency ventilation

Videos on High frequency ventilation

Evidence Based Medicine

Cochrane Collaboration on High frequency ventilation

Bandolier on High frequency ventilation

TRIP on High frequency ventilation

Clinical Trials

Ongoing Trials on High frequency ventilation at Clinical Trials.gov

Trial results on High frequency ventilation

Clinical Trials on High frequency ventilation at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on High frequency ventilation

NICE Guidance on High frequency ventilation

NHS PRODIGY Guidance

FDA on High frequency ventilation

CDC on High frequency ventilation

Books

Books on High frequency ventilation

News

High frequency ventilation in the news

Be alerted to news on High frequency ventilation

News trends on High frequency ventilation

Commentary

Blogs on High frequency ventilation

Definitions

Definitions of High frequency ventilation

Patient Resources / Community

Patient resources on High frequency ventilation

Discussion groups on High frequency ventilation

Patient Handouts on High frequency ventilation

Directions to Hospitals Treating High frequency ventilation

Risk calculators and risk factors for High frequency ventilation

Healthcare Provider Resources

Symptoms of High frequency ventilation

Causes & Risk Factors for High frequency ventilation

Diagnostic studies for High frequency ventilation

Treatment of High frequency ventilation

Continuing Medical Education (CME)

CME Programs on High frequency ventilation

International

High frequency ventilation en Espanol

High frequency ventilation en Francais

Business

High frequency ventilation in the Marketplace

Patents on High frequency ventilation

Experimental / Informatics

List of terms related to High frequency ventilation

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Overview

High frequency ventilation is a type of mechanical ventilation that employs very high respiratory rates (>150 breaths per minute) and very small tidal volumes (usually below anatomical dead space). The primary goal of HFV is to achieve ventilation and oxygenation at a reduced risk of ventilator induced lung injury (VILI). This is commonly referred to as lung protective ventilation.

Ventilator induced lung injury

Ventilator induced lung injury is caused by multiple factors. The human lung is designed to ventilate effectively by using negative pressure in the thorax. Once positive pressure is applied, some degree of VILI is likely to occur.

One major causative factor is the over stretching of the airways and alveoli. During mechanical ventilation, the flow of gas into the lung will take the path of least resistance. Areas of the lung that are collapsed (atelectasis) or filled with secretions will be under inflated, while those areas that are relatively normal will be over inflated. These areas will become over distended and injured. This may be reduced by using smaller tidal volumes.

During positive pressure ventilation, atelectatic regions will inflate, however the alveoli will be unstable and will collapse during the expiratory phase of the breath. This repeated alveolar collapse and expansion (RACE) will cause VILI. By opening the lung and keeping the lung open RACE (and VILI) is reduced.

Types of High Frequency Ventilation

There are different flavors 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.

High Frequency Oscillatory Ventilation (HFOV)

High Frequency Oscillatory Ventilation is characterized by high respiratory rates generally between 3-7 hertz (180-420 breaths per minute). In HFOV the pressure oscillates (60-90 cmH20)around the constant distending pressure (equivalent to the PEEP - usually around 20-30 cmH20). Thus gas is pushed into the lung during inspiration, and then pulled out during expiration. HFOV generates tidal volumes of 1-3 mL/kg; less than the dead space of the lung. Tidal volume is dependent on endotrachial tube size, power and hertz. Different mechanisms of gas transfer come into play in HFOV compared to normal mechanical ventilation. It is used in patients who have hypoxia refractory to normal mechanical ventilation severe ARDS, ALI and other other Oxygenation issues that cannot be corrected with normal means of ventilation.

High Frequency Jet Ventilation (HFJV)

High Frequency Jet Ventilation employs a small cannula placed in the airway at the opening of the endotracheal tube (ett). A high pressure ‘’jet’’ of gas flows out of the cannula and into the airway. This jet of gas occurs for a very brief duration, about 0.02 seconds, and at a very high frequency: 10-20 hertz. Conventional mechanical breaths are frequently required to aid in ventilation.

High Frequency Flow Interruption (HFFI)

High Frequency Flow Interruption is similar to HFJV but the gas control mechanism is different. Frequently a rotating bar or ball with a small opening is placed in the path of a high pressure gas. As the bar or ball rotates and the opening lines-up with the gas flow, a small, brief pulse of gas is allowed to enter the airway. Frequencies for HFFI are typically limited to maximum of about 15 hertz.

High Frequency Positive Pressure Ventilation (HFPPV)

High Frequency Positive Pressure Ventilation is typically utilized by using a conventional ventilator at the upper frequency range of the device (typically 90-100 breaths per minute). A conventional breath type is used and tidal volumes are usually higher than (HFOV, HFJV and HFFI). With newer and specifically designed devices becoming popular, HFPPV is rarely used clinically any more.

References

Template:WH Template:WikiDoc Sources