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Wednesday, December 19, 2012

What is a ventilator?

A ventilator is a machine that breathes for a patient.  Most are set up in critical care units in hospitals, but some patients require home ventilators.

Most of the machines today are micro-processors.  Depending on the mode and other settings dialed in determines how a patient will breathe.

Some modes of ventilation do all the breathing for the patient, while others allow the patient control the ventilator.

This distinction is important because when a patient is not breathing, perhaps due to paralysis either intentional or unintentional, it's important to "control" all his breathing.  Control is also nice when a patient is very sick, has very sick lungs or a very sick heart, and you want the patient to rest completely.  In these cases you'll want to paralyze the patient and set the ventilator to a control mode -- complete control of all breaths.

Yet when a patient is awake and alert, or just waking up, it feels exorbitantly uncomfortable having air forced into your lungs.  For this reason sedation and paralytics are necessary to use control modes.  Yet when a patient is not awake, it's hard to know when a patient is ready to come off the ventilator.  Hence, newer modes were needed that allowed the patient to have more control over his breathing, as opposed to the ventilator doing all the work.

For this reason, most -- probably all -- modern ventilators allow for control modes, but most modes allow for the patient to control the ventilator.  This has the advantage of making being on a ventilator more comfortable, requires the need for less sedatives, and facilitates weaning (that means, doing what is necessary to get the patient off the ventilator.

To place a person on a ventilator a person will either have to be intubated or trached.  Intubation is where an endotracheal tube (ETT) is placed in the patient's airway.  A trach is where a trach tube is inserted into the patients neck.  The ventilator circuit will connect with either the ETT or the trach tube.

Most ventilators are only temporarily used, usually just long enough to allow the patient time to recover from a disease process, or to allow time for a physician to work his magic.  Ventilators are often used during surgeries, and the ventilator is discontinued as soon as the patient starts to wake up.

Some patients have muscle or nerve diseases that make it so their muscles of respiration do not work.  These patients may require a full time ventilator that they can use at home and when they travel.  These ventilators are generally small and easy to set up and use.

Hospital ventilators are generally larger and are generally microprocessor units.  In this way the computer inside allows the patient to control the ventilator instead of the other way around.  The RT will dial in the respiratory rate, tidal volume, flow, and desired mode depending on the patient needs.  There is little math required.

Some hospitals have ventilator management protocols and extubation protocols so that the RT can make the appropriate changes to the ventilator as the patient recovers.  Some hospitals do not have protocols, or have only a few. Where no protocols are present, the doctor makes the calls, and orders what the settings are.

Protocols are nice because they give caregivers the freedom to make necessary changes as the patient improves, in order to provide better comfort and cooperation with the machines.  Most studies show ventilator protocols speed weaning of the patient from the machine, and so most hospitals have some type of protocol.

Ventilators are required any time a patient meets criteria for intubation, and you can see these indications by clicking here.

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Anonymous said...

Picture is wrong... RT periodically checks the vent...

Rick Frea said...

That's funny. I didn't even notice that.