WEBVTT - How Do Ventilators Work? 0:00:01.920 --> 0:00:04.320 Welcome to brain Stuff, a production of I Heart Radio. 0:00:06.320 --> 0:00:10.200 Hey brain Stuff, Lauren Vogelbaum here. This episode is part 0:00:10.200 --> 0:00:13.560 of our ongoing series surrounding the novel type of coronavirus 0:00:13.600 --> 0:00:17.040 identified in twenty nineteen, which causes what's therefore being called 0:00:17.239 --> 0:00:21.000 COVID nineteen. Because everything is a little less scary when 0:00:21.000 --> 0:00:24.880 you understand it better. As the United States and the 0:00:24.920 --> 0:00:27.400 rest of the world scrambled to cope with the COVID 0:00:27.480 --> 0:00:31.880 nineteen pandemic, hospitals are faced with a critical shortage of ventilators, 0:00:31.920 --> 0:00:35.040 the bedside devices that help patients who have difficulty breathing 0:00:35.040 --> 0:00:38.120 on their own. So we wanted to talk today about 0:00:38.159 --> 0:00:42.440 what ventilators are and how they work. U S hospitals 0:00:42.440 --> 0:00:45.440 have about a hundred and sixty thousand ventilators, with another 0:00:45.520 --> 0:00:48.920 twelve thousand, seven hundred available from the federal government's National 0:00:48.920 --> 0:00:52.960 Strategic Stockpile, but it's feared that that will be nowhere 0:00:53.000 --> 0:00:55.120 near enough to cope with all the people who could 0:00:55.120 --> 0:01:00.000 become seriously ill from the virus. All of this has 0:01:00.000 --> 0:01:02.720 suddenly focused attention on a piece of medical equipment that 0:01:02.800 --> 0:01:05.559 most of us probably haven't given much thought to any 0:01:05.560 --> 0:01:09.119 more than we think about breathing itself, but for someone 0:01:09.160 --> 0:01:12.280 who can't get air into their lungs, the device, which 0:01:12.400 --> 0:01:15.720 ranges in price from twenty to fifty dollars according to 0:01:15.720 --> 0:01:21.240 The Washington Post, can be a lifesaver. Ventilators assist patients 0:01:21.280 --> 0:01:24.440 who have a number of different conditions. We spoke by 0:01:24.440 --> 0:01:27.480 an email with Dr Paul F. Courier, director of the 0:01:27.560 --> 0:01:30.520 Respiratory Acute Care Unit for the Division of Pulmonary and 0:01:30.560 --> 0:01:35.160 Critical Care at Massachusetts General Hospital. He said they can 0:01:35.200 --> 0:01:38.680 be used to help people breathe during routine surgery under anesthesia, 0:01:39.120 --> 0:01:42.240 or also when patients are sick and have difficulty breathing 0:01:42.280 --> 0:01:45.960 due to their illness. A small proportion of people who 0:01:46.000 --> 0:01:50.120 become infected with COVID nineteen may develop inflammation in their lungs. 0:01:50.800 --> 0:01:54.720 Courier explained. An even smaller proportion of these patients can 0:01:54.760 --> 0:01:58.600 develop respiratory failure, which is best treated with a ventilator. 0:02:00.000 --> 0:02:02.680 But we also spoke by email with Kenneth Lutchen, dean 0:02:02.760 --> 0:02:05.520 of the College of Engineering and a professor of biomedical 0:02:05.520 --> 0:02:09.720 engineering at Boston University. He said, think of the lungs 0:02:09.760 --> 0:02:13.040 as an elastic balloon. You can expand the balloon by 0:02:13.120 --> 0:02:16.640 having the pressure at the opening mouth be greater than 0:02:16.680 --> 0:02:19.760 the pressure on the other side of it. Normally, we 0:02:19.840 --> 0:02:23.200 breathe by having our muscles expand the chest, which lowers 0:02:23.240 --> 0:02:26.000 the pressure around the lungs inside the body, so that 0:02:26.040 --> 0:02:29.320 the lungs expand. But if the lungs fill up with 0:02:29.400 --> 0:02:32.480 fluid or become highly inflamed, both of which can happen 0:02:32.560 --> 0:02:36.360 with novel coronavirus, then the negative pressures that occur with 0:02:36.520 --> 0:02:40.000 normal breathing are not sufficient to expand the lungs enough, 0:02:40.320 --> 0:02:44.880 and insufficient oxygen and carbon dioxide exchange will result. The 0:02:45.000 --> 0:02:49.240 lucchen continued. The alternative is then to push air into 0:02:49.240 --> 0:02:52.720 the lungs using a ventilator, which creates a positive pressure 0:02:52.760 --> 0:02:56.000 at the mouth the inlet to the intubation tube large 0:02:56.080 --> 0:03:00.359 enough to push enough fresh air in and out each breath. 0:03:01.160 --> 0:03:04.160 Hopefully this can keep the blood, oxygen, and carbon dioxide 0:03:04.240 --> 0:03:07.480 levels close to normal until the inflammation and fluid build 0:03:07.520 --> 0:03:10.360 up subsides and the person can breathe on their own again. 0:03:11.560 --> 0:03:14.840 A ventilator is a boxing mechanical device with a digital 0:03:14.840 --> 0:03:17.480 display on top that typically sits on a cart next 0:03:17.480 --> 0:03:20.840 to a patient's bed. As the National Heart Long and 0:03:20.960 --> 0:03:24.320 Blood Institute website explains the patient is connected to the 0:03:24.360 --> 0:03:26.919 device by a breathing tube that's inserted through their nose 0:03:27.000 --> 0:03:29.600 or mouth down the throat, which is held in place 0:03:29.639 --> 0:03:31.960 by tape or a strap that fits around the head. 0:03:32.840 --> 0:03:35.520 The tube in the airway can cause some discomfort and 0:03:35.560 --> 0:03:39.080 also affects the patient's ability to talk and eat. That's 0:03:39.120 --> 0:03:41.760 why the care team may insert another tube into a 0:03:41.840 --> 0:03:44.960 vein to feed the patient nutrients, or if the person 0:03:45.040 --> 0:03:47.120 is going to be on a ventilator for a long time, 0:03:47.520 --> 0:03:50.080 insert a feeding tube that goes directly into the stomach 0:03:50.160 --> 0:03:55.040 or small intestine through a surgically created opening. Having a 0:03:55.120 --> 0:03:58.160 tube down your throat isn't exactly pleasant, but it is 0:03:58.240 --> 0:04:03.000 important electionics blamed Without intubation, Several things can threaten the 0:04:03.000 --> 0:04:06.120 ability of the ventilator to do its job. Perhaps the 0:04:06.160 --> 0:04:09.000 most important is that if the ventilator just blew into 0:04:09.000 --> 0:04:12.200 the mouth, the delivered volume may not all go into 0:04:12.240 --> 0:04:14.520 the lung. Some of it could leak out the nose, 0:04:14.560 --> 0:04:17.000 which is connected to the mouth, or can end up 0:04:17.040 --> 0:04:19.880 expanding the cheeks of the person rather than going into 0:04:19.880 --> 0:04:23.599 the lung. To get all of this to work, hospitals 0:04:23.640 --> 0:04:28.400 depend upon the expertise of highly trained professionals called respiratory therapists. 0:04:29.320 --> 0:04:32.040 We also spoke via email with Timothy R. Myers, a 0:04:32.080 --> 0:04:35.640 respiratory therapist and chief business officer of the American Association 0:04:35.720 --> 0:04:40.240 for Respiratory Care. He said, the respiratory therapist determines the 0:04:40.279 --> 0:04:44.039 appropriate settings to match the patient's respiratory needs based on 0:04:44.160 --> 0:04:48.720 the underlying disease condition. From that point, they provide constant monitoring, 0:04:48.760 --> 0:04:51.719 an assessment, and modify the setting as the patient's condition 0:04:51.839 --> 0:04:56.240 improves or worsens. This would include non invasive monitoring and 0:04:56.400 --> 0:04:59.719 measurements from blood analysis to look at oxygen and carbon 0:04:59.720 --> 0:05:04.440 dio side levels. This requires a lot of careful management 0:05:04.600 --> 0:05:08.160 because lungs are pretty complicated. While it's useful to think 0:05:08.160 --> 0:05:11.799 of the lungs as a balloon for illustrative purposes, in reality, 0:05:11.960 --> 0:05:15.719 Myers explained their quote more like a network of millions 0:05:15.720 --> 0:05:18.960 of balloons that must transfer gases between the lungs and 0:05:19.080 --> 0:05:22.839 the circulatory system. When the lungs are damaged or diseased, 0:05:23.160 --> 0:05:26.599 each lung and the millions of balloons require gas entry 0:05:26.720 --> 0:05:30.520 in and out differently than when they're healthy. Each patient 0:05:30.720 --> 0:05:34.880 is unique. In recent years, there have been some advances 0:05:34.920 --> 0:05:38.760 and how ventilators are used. Courier said research has shown 0:05:38.760 --> 0:05:43.000 that using low breath size and low pressures improves outcomes. Also, 0:05:43.160 --> 0:05:46.480 patients with severe respiratory failure may at times be turned 0:05:46.480 --> 0:05:49.080 on their stomachs while on the ventilator, a process called 0:05:49.080 --> 0:05:53.120 prone positioning, which can often improve their oxygen levels. Finally, 0:05:53.240 --> 0:05:56.360 for some patients whose oxygen levels remain low despite being 0:05:56.360 --> 0:05:59.320 on a ventilator, they may be able to receive extra 0:05:59.400 --> 0:06:05.039 corpore membranous oxygenation. In some very specialized centers, this highly 0:06:05.080 --> 0:06:08.000 intensive therapy can circulate the blood outside of the body 0:06:08.200 --> 0:06:13.480 to provide additional oxygen. Luchen's research focuses on developing safer 0:06:13.520 --> 0:06:18.000 mechanical ventilators, he said. Initially, the ventilator is working to 0:06:18.040 --> 0:06:21.560 save a life by keeping proper oxygen and carbon dioxide levels, 0:06:22.080 --> 0:06:25.080 but it does this by pushing air in and exposing 0:06:25.120 --> 0:06:29.080 the lung to abnormal pressures, often larger pressures to help 0:06:29.120 --> 0:06:34.200 expand a stiffer and or narrower lung. Also, a ventilator 0:06:34.279 --> 0:06:37.320 is programmed to give the exact same breath every time, 0:06:37.720 --> 0:06:40.360 where normal breathing varies a little from breath to breath 0:06:40.680 --> 0:06:44.200 and we periodically take a big breath. He explained that 0:06:44.279 --> 0:06:47.880 injuries can occur from those large, repetitive pressures, which could 0:06:47.920 --> 0:06:53.279 eventually prevent the ventilator from providing enough gas exchange. That's 0:06:53.279 --> 0:06:57.200 why Luchen is working with lead investigator Balisuki, a professor 0:06:57.240 --> 0:07:00.799 of biomedical engineering at Boston University, on a concept called 0:07:00.920 --> 0:07:05.400 variable ventilation, in which the ventilator delivers variable breaths similar 0:07:05.440 --> 0:07:09.520 to a natural breathing pattern, to avoid repetitive abnormal pressures 0:07:09.720 --> 0:07:13.640 in the same location when a person breathes. Trials and 0:07:13.680 --> 0:07:16.000 animals have shown that this type of ventilation is less 0:07:16.000 --> 0:07:18.360 likely to cause injuries, but it hasn't yet been tested 0:07:18.360 --> 0:07:23.440 in humans. With the current shortage of ventilators, manufacturers are 0:07:23.600 --> 0:07:28.160 ramping up production. Medtronic, one of the world's major ventilator makers, 0:07:28.440 --> 0:07:31.000 is gearing up to double its output by adding shifts 0:07:31.040 --> 0:07:33.840 to keep its Irish manufacturing plant running around the clock. 0:07:34.600 --> 0:07:38.720 But manufacturers face a challenge in increasing production because ventilators 0:07:38.800 --> 0:07:46.320 must be built with great care. Today's episode was written 0:07:46.360 --> 0:07:49.120 by Patrick J. Tiger and produced by Tyler Klang. For 0:07:49.200 --> 0:07:51.040 more on this and lots of other topics, visit how 0:07:51.040 --> 0:07:54.040 stuff Works dot com. Brainstuff is production of I heart Radio. 0:07:54.200 --> 0:07:56.360 For more podcasts for my heart Radio, visit the iHeart 0:07:56.400 --> 0:07:58.680 Radio app, Apple Podcasts, or where ever you listen to 0:07:58.720 --> 0:08:08.480 your favorite shows.