Ventilators: A Comprehensive Guide

In 1928, doctors used the first ventilator to help a young patient with respiratory paralysis (per Harvard T.H. Chan School of Public Health). Originally called the "iron lung," the first respirator came into high demand during a polio epidemic a few years after its initial trial, because the machine could give short-term help to the body as nerves and muscles affected by the virus recovered (via STAT). In addition, this gadget made it so that respiratory failure no longer resulted in death.

According to the National Heart, Lung, and Blood Institute, ventilators move air in and out of your lungs through a mask or breathing tube. Used for patients who cannot breathe on their own, most ventilators are found in hospitals or medical transports, though some do exist for use in the home. Kathy Langley, a nurse and instructor at the University of Alabama Birmingham School of Nursing, explains to UAB News that "It becomes an external set of lungs. The ventilator allows the patient to rest and to heal while the machine does the work of the lungs."

When placed on a ventilator, a tube goes into your airways, and a device pushes air into your lungs through that tube (per Self). According to the American Thoracic Society, this endotracheal tube (ET tube) goes through your mouth or nose and into your windpipe. The other end connects to the ventilator. Oxygen is not only pushed into your lungs, but this machine also maintains pressure in your lungs so your alveoli don't collapse. Additionally, the ET tube enables medical professionals to suction out any mucous buildup.

The oxygenation and ventilation pressure settings must be personalized and monitored while you remain on the machine (via Self). The three types of breath settings available on a ventilator are controlled, assisted, and supported. REBELEM explains that when your ventilator is set to controlled breathing, it does all of the work, and breaths are delivered at a specific interval. The setting of assisted breaths gets activated when you try to breathe on your own and suck on the tube to create a change in pressure. The ventilator then takes over and does the breathing work for you. However, if you fail to initiate the breath, the machine still has a setting that causes it to breathe for you automatically. Finally, supported breath mode offers minor support to patients who can trigger the ventilator independently but who need help completing the breathing motions.

Medical professionals use pressure-cycled ventilators to either partially or entirely aid patient-initiated breathing to reach a consistent airway pressure during each inhalation (per ScienceDirect). Once the pre-set airway pressure is met, exhalation begins. Though the force of the pressure remains the same for each inhalation, the volume of oxygen delivered changes depending on airway resistance, lung compliance, and ventilator stability (per Tracheostomy Education).

RT Magazine reports that pressure-cycled ventilators offer several patient advantages. First and foremost, the machine correlates patient needs and flow delivery. As a result, you are more comfortable and are less in need of sedatives and other medications while using the device. Furthermore, pressure-cycled ventilators enhance the air dispersion throughout the lungs, reducing barotrauma risk while improving the oxygen delivery to your arteries and tissues, especially during bronchospasms that cause high pressure and low distribution.

Pressure-cycled ventilation is most often used to remove patients from mechanical ventilation, enabling their lungs to take on more work with each breath (via Merck Manuals).

Going on a ventilator starts with the administration of a combination of sedatives and paralytic agents (per Insider). You may also get medication that causes you to become unconscious (via The Ohio State University Wexner Medical Center). Brian Boer, an ICU doctor and pulmonologist at the University of Nebraska Medical Center, told Insider that this reduces gagging during the procedure. Yale Medicine's Lauren Ferrante, a pulmonary and critical care specialist, explains that it also helps prevent self-harm if you suffer from delirium or confusion while on the ventilator.

Dr. Boer further explained that a doctor uses a speculum to widen your airway and slides the breathing tube down to your lungs (via Insider). At that point, a small cuff gets placed around the tube to prevent particles from escaping, and then the machine gently pumps highly oxygenated air at a steady rate, simulating breathing. You will also have a feeding tube inserted into your nose or mouth because you can't eat while on a ventilator. Finally, the medical team takes an x-ray to ensure proper placement and an ultrasound to check for proper lung inflation. The entire process takes around 15 minutes.

The American Thoracic Society explains that ventilators help to maintain life while someone heals. However, ventilators on their own do not treat the illnesses or accidents that caused their initial need. Therefore, those caring for you while you're on a ventilator do their best to ensure your time on the device is as limited as possible.

However, the ultimate length of time depends on several factors. One element that comes into consideration is your health before you needed a ventilator. For example, if your lungs weren't strong before you were intubated or you have other damaged organs, your stay on a ventilator would be longer than someone who didn't have the additional problems. Pulmonologist Lauren Ferrante at Yale Medicine adds that the initial reason your doctor chose to use a ventilator also comes into play when determining how long you will need it. These machines may be used for just a few hours during surgery, or for days to weeks in the case of lung injuries and severe illnesses like pneumonia. Additionally, she adds that the longer you stay on a ventilator, the weaker your lungs become.

Though ventilators help keep you alive by aiding you in breathing when you cannot do so on your own, they are not without complications. One of the most common and the most serious is developing pneumonia or another chest infection while you are intubated (per the National Heart Lung and Blood Institute). In fact, the Virginia Department of Health reports that nearly 50,000 cases of ventilator-associated pneumonia (VAP) occur annually, and this type of illness accounts for close to 40% of all hospital-related pneumonia infections.

Merck Manuals defines VAP as occurring after at least two full days of intubation. The infection results from a breach of your airway defense system. When you are on a ventilator, you cannot cough or clear mucous that accumulates in your lungs, resulting in bacteria pooling in both the tube cuff and the tube itself. Signs of VAP include fever, increased white blood cell count and tracheal secretions, and decreased oxygenation. Testing for VAP consists of a chest x-ray and blood culture. If you have the infection, VAP gets treated with antibiotics.

According to a study published in Tanaffos, VAP occurs in up to one-quarter of all ventilated patients. And it's a quite serious complication, as the mortality rate for VAP is nearly 50% (via Institute for Healthcare Improvement).

According to Benumof's Airway Management (Second Edition), ventilator-induced lung injury (VILI) is defined as acute lung damage resulting from the use of mechanical ventilation. Patients most often present with hypoxemia when VILI occurs. Doctors diagnose VILI by ruling out other causes of low blood oxygen levels through CT scans and x-rays, according to Ventilator-Induced Lung Injury (VILI).

Clinics in Chest Medicine details four types of VILI: barotrauma, volutrauma, atelectrauma, and biotrauma. Barotrauma and volutrauma are both caused by high lung pressure. Atelectrauma is attributed to the stress on the lung caused by repeated opening and closing of alveoli while on a ventilator (per European Society of Intensive Care Medicine). Finally, biotrauma is an inflammatory response to mechanical lung injury.

Researchers reported in Nature Communications that part of the reason ventilation can lead to lung injury is that the body sees the ventilator as an invader. To fight this enemy, inflammation occurs. Your body then releases a microRNA to combat the irritation. However, the body fails to make enough to fight the ventilator it perceives as the enemy. The researchers note, though, that if this bodily response can be harnessed and the microRNA more effectively delivered, it may help to prevent lung injury during ventilation — though more research on this issue is needed.

According to a review published in the British Medical Journal, one in five ventilated patients fails to come off the machine the first time their medical team tries to wean them. The number of failures tends to increase as patients stay ventilated longer. The primary reason many patients fail to wean is the disproportion between your muscles' work while breathing and their capacity to do the job (per Cancer Therapy Advisor). Another cause of failure is cardiac disease resulting in inadequate blood flow and oxygen delivery to your respiratory muscles, causing fatigue.

The best way to determine if a patient is ready to be weaned off a ventilator is by performing a series of tests that show oxygen concentration, artery tension, and pressure and sedation levels (per the British Medical Journal). These evaluations can be performed daily, lowering the number of patients who remain intubated for longer than 21 days and decreasing mortality rates. The most common sign of failure is rapid shallow breathing upon disconnection of the ventilator.

Medical professionals sometimes perform a tracheostomy on patients who fail to wean (via the Intensive Care Hotline). During this procedure, a tube gets placed in their neck, allowing them to breathe. Tracheostomy is easier to tolerate, decreases sedation, makes suctioning and talking easier, and improves the ability to brush teeth and maintain oral hygiene. As the patient heals further, eventually the hope is that the trache tube can also be removed, and the patient will breathe entirely on their own again (per the Intensive Care Hotline).