Hello, everyone, and welcome to the Society of Critical Care Medicine Congress 2023. My name is Javier Amador-Castaneda, and I am a respiratory care practitioner in the Medical Intensive Care Unit at Columbia University Urban Medical Center in New York City. I have no relevant financial relationships to disclose at this time. And today, we're going to be talking about the adoption of prone ventilation in COVID-19. And will the adoption occur after the pandemic? Our learning objectives is to understand the physiology behind prone positioning, learn about the PERCEIVA study, and understand how COVID-19 accelerated the adoption of proning. Let us begin by defining what proning is. In layman's terms, proning is essentially the process of turning a person from the back onto their abdomen. So how does proning work, and why does it improve oxygenation? Let us review what happens in the lungs when in the supine position versus prone positioning. On the top left-hand corner, we have an axial view of the thoracic cage, and to the right of it, we have a sagittal view of the thoracic cage and the supine position. Now, there is a superimposed pressure from the heart and abdomen to the dorsal regions of the lung. Part of it is because the heart applies approximately 5 to 10 centimeters of water pressure onto the dorsal part of the lung. In addition, the differences in organ densities between the abdominal compartment and the thoracic compartment is 10 liters versus 5 liters of thoracic volume, and the hydrostatic pressures of the abdomen far exceed the pleural pressures in the thoracic cavity by a factor of 5. This can be even increased if the patient is morbidly obese, if the patient has abdominal compartment syndrome. As a result, the combination of the pressure applied from the mediastinum and the abdomen onto the dorsal part of the lung causes a decrease in transpulmonary pressures compared to the ventral transpulmonary pressure of the lung. In ARDS, the increased weight of edematous, injured tissue settles on the dorsal lung region of the lung due to the gravity causing alveolar collapse. This can be seen on the dark purple regions of the lung, signifying an increased level of arylectasis. So now, we have perfusion but no ventilation on the dorsal region of the lung. This VQ mismatching is what causes such low levels of oxygen. Now pretend this patient is intubated. The volumes that we deliver to this patient are going to go to the path of least resistance. Since there is a significant amount of arylactatic lung in the dorsal region of the lung, the volume mainly goes to the ventral region of the lung, causing an overdistension of the alveoli. Hence, the increase in ventral transpulmonary pressures. And if you recall, your transpulmonary pressure is your pressure gradient between your alveolar pressure minus your pleural pressure. So what happens now in the permposition? Well, let's start by noting the decrease in pressure from the heart and abdomen onto the dorsal region of the lung. As we recruit the dorsal lung, we decrease ventral alveolar overdistension, ventilating the lungs in a more homogeneous state. This causes an improvement in VQ matching. And as we continue to recruit the lung, the increase in aeration and oxygen tension should mitigate hypoxemic vasoconstriction. This promotes a decrease in pulmonary vascular resistance and right ventricular afterload. So pronin may actually improve RV function in some of these patients. Let's briefly talk about the PROSIVA study conducted by Dr. Garin and his colleagues in 2013. This was a multi-center randomized control trial that evaluated the effects of early application of prompositioning on outcomes in patients with severe ARDS. The inclusion criteria consisted of ARDS patients as defined by the American-European consensus, endotracheal intubation and mechanical ventilation for less than 36 hours, and PaO2 to FiO2 ratios of less than 150 millimeters of mercury, and FiO2 of 60% and higher, and PEEP of 5 centimeters of water pressure and higher, and total volumes of 60 cc per kilogram of predicted body weight. The study concluded that the use of prompositioning significantly reduced 28-day mortality from 33% down to 16%, and 90-day mortality rates from 41% down to 24%. There were also fewer mechanical ventilation days, and there was an increase in successful extubations and decreased reintubation rates. So how often was prompositioning being utilized before COVID-19? Dr. Hodgeberg and colleagues conducted a multi-center retrospective cohort study in Maryland comparing prompositioning use in COVID-19 versus historic ARDS in the state of Maryland. On this graph, you can see data collected from 2018 to 2019 of community hospitals and academic centers that were proning patients with ARDS prior to COVID. As you can see, after meeting oxygenation criteria, about 9% of patients were prone within the first 48 hours, with academic centers proning slightly more than community hospitals. Nationwide, only 6-14% of patients were being prone. This was due to a lack of knowledge on the benefits of proning, a lack of trained staff in proning, and insufficient proning protocols in place nor set guidelines to follow. The COVID-19 pandemic hit the U.S., and we had to quickly learn new skills. So COVID was the catalyst to the adoption of prompositioning and implementation of new proning protocols. As you can see on this graph, data collected between 2020 and 2021 between community hospitals and academic hospitals show an increase in the adaptation of proning to as high as 58% in the state of Maryland. Nationwide, the adaptation of proning increased between 25 to 62%. The pandemic helped to spread awareness of prompositioning and its benefits, new protocols and guidelines were implemented, and there was an increase in trained staff leading to specialized proning teams in certain hospitals. So this brings me to the question, will de-adoption of prone ventilation occur after the pandemic? Well, let's look at the information that we have. There are studies such as the PROSIVA trial that show a decrease in 28-day and 90-day mortality rates by proning patients for at least 16 hours within the first 36 hours of being intubated and started on mechanical ventilation. As a result of COVID-19, we now have more trained staff in the process of proning, more protocols and guidelines in place, and various resources to rely on such as videos, infographics, guidelines, and protocols. We have increased our proning rates from 14% pre-COVID to as high as 62% during COVID. Should we really stop the use of proning after the pandemic is over, despite having candidates that meet criteria for proning? So should we stop proning patients at the conclusion of this pandemic? And the simple answer is no. We should continue to prone patients after the pandemic is over. It is important to continue to maintain new proning protocols that were implemented as a result of the pandemic. Continue to identify the right patient to prone and check for any contraindications. Prone in a timely manner within 72 hours of intubation and for at least 12 hours. Have the right staff that is properly trained and capable of proning. Have the right equipment necessary. And follow proning protocols as per your hospital policy. The retention of proning on the indicated patients for severe hypoxemia, despite having COVID or not, despite being in a pandemic or not, should not be discontinued until further studies show otherwise. This concludes my presentation. Thank you so much for joining. If you have any further questions, please do not hesitate to contact me and thank you for joining SCCM Congress 2023. I look forward to seeing you next year. Thank you.

prone ventilation

COVID-19 patients

pandemic

physiology

oxygenation