The US is running short on ventilators amid the coronavirus pandemic. Here's how they work and why they're so important.

• Ventilators are in short supply in the US.
• Reported symptoms of patients with coronavirus include difficulty breathing.
• Ventilators, which blow air into patients' lungs to assist the natural process of breathing, could be the difference between life and death for some.
• Visit Business Insider's homepage for more stories.

The US does not have enough ventilators, the medical machines that could be the difference between life and death for COVID-19 virus patients struggling to breathe.

A February report from the Center for Health Security at Johns Hopkins revealed the US has about 160,000 ventilators ready for use in hospitals, with another 8,900 held in a national reserve. New York Gov. Andrew Cuomo has warned repeatedly that his state, the epicenter of coronavirus in the US, is at risk of running out of the machines.

About 1 million Americans might need a ventilator during the coronavirus outbreak, according to projections from Dr. James Lawler, an infectious diseases specialist and public health expert at the University of Nebraska Medical Center. Lawler's projections didn't include a time frame, and all of those people might not need a ventilator at the same time.

How a ventilator works

Some patients with COVID-19 have reported shortness of breath and trouble breathing. A ventilator, which varies in appearance but typically has a square or rectangular base with a hose-like pipe on one side which carries air from the machine to the patient, would be able to help struggling patients.

"Basically a ventilator is something that blows air into your lungs to assist the natural process of breathing," Dr. Nicholas Hill, the chief of pulmonary and critical care at Tufts University School of Medicine, told Business Insider.

There are fundamentally two different kinds of respiratory failure, Hill said.

The first kind is called hypercapnic respiratory failure, which is when not enough air is getting in and out of the lungs, causing carbon dioxide to build up. Non-invasive ventilation would be used to treat this sort of failure.

The second kind, called hypoxemic respiratory failure, is when not enough oxygen is entering someone's bloodstream. This sort of failure is often caused by infections like pneumonia, which can cause damage to the lungs. The coronavirus is also shown to cause such damage.

When this happens, Hill said, the lungs become inflamed and build up fluid, causing them to not function properly.

"We treat that by giving higher fractions of oxygen," Hill said. "We can give you 100% oxygen to get your oxygen levels in the blood up, but we have to be careful because that 100% oxygen could be damaging too."

Addressing the ventilator shortage in New York

In New York, the state with the most reported COVID-19 patients in the country, there are still enough ventilators to sustain the fewer than 800 coronavirus patients who currently need to be on the machines, Gov. Cuomo said at a press conference on Tuesday morning. But the governor has estimated that the state will soon need 30,000 ventilators for the virus' peak, which is expected to take place in a few weeks.

The limited availability of ventilators has prompted Cuomo to propose using one ventilator for two patients if things get worse. That could be risky for patients since ventilators are usually built to help just one person at a time. If ventilators are shared among two patients, they would each need to have similar lung capacities and body sizes for things to go smoothly.

Doing that would be a "desperate, desperate measure," said Hill, who said focusing on manufacturing more ventilators would be the best option to save lives.

Do you work in healthcare? Business Insider would like to hear what you're seeing on the front lines of the coronavirus response. Email the author at ylee@businessinsider.com.

Hilary Brueck contributed reporting.

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