How Do Ventilators Actually Work?


We asked a doctor at UCLA to break it down for us.

Amid talk of ventilator shortages, our Wake-Up Call newsletter (subscribe here) is examining how these live-saving machines actually work. Dr. Nina Shapiro, a pediatric airway surgeon at Mattel Children’s Hospital UCLA, explains how health care professionals manage the subtleties of ventilators — and keep patients alive.

During the challenging days of Covid-19, we’ve all been hearing so much about the need for ventilators. As a Californian, I was thrilled to hear that Governor Gavin Newsom decided to send off 500 of these precious machines to states in need. I’m a pediatric airway surgeon. In my field, ventilators are near and dear to our hearts; they are part of our daily work. Until these past weeks, I had never even considered the notion of a ventilator shortage. The concept is frightening, and the reality is terrifying. Yet here we are.

But in my experience, I know that it’s not the machines that keep babies and children alive — it’s the people behind them that are indispensable.

My anesthesia colleagues, intensive care specialists, and respiratory therapists carefully and skillfully manage ventilators for innumerable types of breathing issues. They keep precious premature newborns alive when their lungs are too immature to breathe for themselves, and keep critically injured children alive. They keep hearts beating, lungs oxygenating, and help bodies heal.

And I don’t think many people realize that every ventilator isn’t just handled by an expert, but a team. Even before a ventilator is used, respiratory specialists make sure it’s clean and check its gas circuits, make sure all of the gauges are calibrated, ensure it’s functioning perfectly. These complex machines are useless without the professionals who are pre-checking them, running them 24 hours per day, seven days per week. A ventilator requires meticulous management. There’s no simple “on/off” switch.

I recently connected with Hratch Kayichian, an experienced respiratory therapist at UCLA Medical Center. I have been a surgeon at the Center for over two decades — and count over 200 amazing respiratory specialists as my colleagues.

Hratch offered some great perspective on what caring for a patient on a ventilator entails. First, in a delicate procedure, either an anesthesiologist, intensive care specialist, or otolaryngologist (ear, nose, and throat specialist), places a breathing tube, a plastic straw-like tube, through a patient’s mouth. It extends into the voice box to the windpipe. This is the patient’s lifeline — it acts as a conduit to receive every inhale and exhale while on a ventilator.

As soon as the breathing tube is placed, in these days of Covid-19 usually because a patient is unable to keep their breathing going on their own, the ventilator goes into action. There’s so much that goes into ventilator management, Here are a few components that need to be continuously balanced:

  • Oxygen: The air we breathe, polluted or not, contains about 20% oxygen. If our lungs are not working, there may not be enough oxygen to get to our bloodstream. Ventilators can give up to 100% oxygen, if needed, to help transport oxygen from the lungs to the blood. The patient’s blood oxygen levels are continually monitored, to make sure that the oxygen levels in the ventilator are enough. If they’re too high, it can also lead to blood level imbalance.
  • Pressure: When we breathe in and out, we can breathe deeply or more shallowly. The ventilator can provide different amounts of pressure — either gently or forcefully pushing air into the lungs. This pressure often depends on how much lung disease or damage there is.
  • Rate: We breathe at different paces — ranging from fast to slow. The ventilator’s rate can be altered to generate a specific frequency of breaths per minute.
  • Inspiratory time: How long does it take you to fill up your lungs? The ventilator has a setting to fill them up quickly or more slowly.
  • Volume: This is the amount of air taken in during each breath. You can fill your lungs up with a deep breath — or just take a small one. Individuals can vary. Breaths from a ventilator give a specific volume of air for each breath, depending on the size and age of the patient, and their type of lung problem.
  • PEEP: This is one of my favorite terms, since it sounds kind of cute. “PEEP” stands for “Positive End-Expiratory Pressure.” (I know, not so cute-sounding any more.) Healthy lungs exert this pressure to help our alveoli (tiny air sacs in our lungs) stay open and transport oxygen to our blood. Mechanical ventilators need to create a certain amount of “PEEP” on lungs that aren’t functioning on their own.

Those are the bare bones of ventilator settings. But there’s more! So much goes into tweaking the subtleties. As the breathing tube acts as the lifeline, a lot can be done with and through this tube.

  • Breathing tube issues: If the breathing tube is not exactly in the right place — either too high or low in the windpipe — there can be difficulties ventilating the patient. This can be checked with chest X-rays or by placing fiberoptic scopes through the tube.
  • Tube blockage: Sometimes too much mucus gets stuck in the breathing tube. This needs to be fixed with special suction tubes, which can be hard to finesse.
  • Lung problems: Besides the issue of ventilation, the lungs often need more direct treatments. For example, if small airways in the lungs close down, a patient could be given other types of treatment (similar to asthma inhaler medications).

When a patient’s lungs begin to function again on their own, all these individual processes are gradually reversed. Thankfully, we’re hearing about more and more Covid-19 patients ‘coming off of ventilators,’ after being on them for up to several weeks.

Just as specialists use fine-tuning to put patients on ventilators, they have to use the same discretion to “wean” them off of them — followed by incredibly close monitoring, because a patient often still requires breathing treatments or oxygen from a face mask. That’s why it’s never an “all-or-nothing” situation. In this process, many of the most carefully planned hours are when patients finally start breathing on their own.

It’s terrifying to fathom not having enough ventilators. But it’s even more terrifying to not have adequate protection for colleagues who are so closely managing these critically ill, ventilated patients. While speaking with Hratch today, I realized how fortunate we are to have such caring team members treat our patients. These coveted ventilator machines are replaceable. The folks keeping these machines going are not.

Dr. Nina Shapiro is Professor of Head and Neck Surgery at UCLA and Director of Pediatric Ear, Nose, and Throat at Mattel Children’s Hospital UCLA. She is a contributor to Forbes Healthcare the author of HYPE: A Doctor’s Guide to Medical Myths, Exaggerated Claims and Bad Advice: How To Tell What’s Real and What’s Not.

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