Hi, everybody. My name is Forrest Orm. I'm a third-year internal medicine resident at Legacy Health. I'm giving a presentation on awake proning with high-flow nasal cannula and COVID ARDS. So, I'll just start with a case from our hospital from last March when COVID first started. He was a 56-year-old Hispanic male, medical history of type 2 diabetes, A1C of 6.8, hypertension, immediate for acute hypoxic respiratory failure. COVID PCR came back positive, started on a moderate flow nasal cannula, progressed to high flow. Eventually, given remaining saturations less than about 90%, the decision was made to intubate. Seventeen days later, he was extubated, had a complicated ICU course, and was eventually discharged to SNF. This is a second case from our same hospital in November when Oregon had their kind of peak COVID, kind of shows how far we've come in our knowledge of COVID-19 management. This patient was a 67-year-old black man with a medical history of hypertension, preserved heart failure, type 2 diabetes, and osteoarthritis, came in with acute hypoxic respiratory failure, and his COVID-19 PCR was positive, started on four liters of mod flow, progressed to a high-flow nasal cannula. We set a PAO2 goal of 85% cell proning as possible, and he stayed that way for about eight days before he was transferred back to the medical wards and was eventually discharged home. So, I just kind of wanted to talk about the last two cases. I think the big difference is when we first started dealing with COVID was that we ended up intubating people earlier than I think we maybe should have, and we didn't utilize self-proning or hyphalonasal cannula to the same degree as we are doing now. And I think that the utility of hyphalonasal cannula and proning has really been helpful. The concept of proning wasn't really introduced until the 1970s, initially as a way to improve oxygenation. Physiologically, proning patients reduces their trans-pulmonary pressure, decreases the shunt fraction, and allows for improved alveolar recruitment without any changes in hemodynamic status. Early studies demonstrate improvement in oxygenation, but no real benefit in mortality. These studies tended to be underpowered, and it wasn't until the 2013 PROCEVA trial, which effectively demonstrated a mortality benefit in ARDS, and it's now fairly commonplace in all ARDS management. And I think we're seeing now more and more that it can be done while the patient's awake, not just intubated, sedated, and potentially paralyzed. Discussing too about COVID-19 pneumonia and ARDS, you know, there's a lot of discussion about whether or not COVID-19 is similar or different to typical ARDS, and really there's a dearth of data on COVID-19. However, there are some things that we know, which is that COVID-19 patients tend to be somewhat atypical for ARDS. There are a number of great review articles on this topic, and we don't have time to get into all of the subtle differences. The graph here on the right was compiled by Dr. Stephen Archer at All for Circulation in July 2020, and compares traditional ARDS with COVID-19 and high-altitude pulmonary edema. And then it shows that COVID-19 patients tend to be profoundly hypoxemic, but have a similar degree of dyspnea. And this is that quote-unquote happy hypoxic, the patient with a terrible chest CT and PAO to chatting on their cell phone. They tend to have relatively preserved lung compliance, and when ventilated, they tend to have a large intrapulmonary shunt. Not that these subtle differences should negate traditional ARDS management, but they may inform some of the subtle nuances which are anecdotally clinically relevant. And in early March, when the COVID-19 pandemic arrived in Oregon, we didn't have much experience with COVID-19 and any of these kind of self-differences, and we were really concerned, as I mentioned earlier, about the kind of quick decompensation of a patient, and we intubated patients once they were working hard and had a PAO2 of less than 90 percent, and I think we were probably wrong to do so. This multi-center study from 2020 from Lee et al. shows that early intubation leads to lower survival rates compared to those patients not intubated. Only about 30 percent of the patients who were intubated early were alive at 80 days compared to roughly 50 percent of patients surviving if intubated late. So the question becomes, what is the data around avoiding early intubation or not even intubating patients? So this study done in 2018 to 2019 by Ding et al, you know, precedes the COVID era, but it does provide good data about high-flow nasal cannula in proning patients with ARDS. It's a small observational study, but looked at ARDS patients with a PDAF less than 200, and if had stable oxygenation, they were placed in high-flow nasal cannula with or without proning. Other patients were given non-invasive ventilation, and the primary endpoint was avoidance of intubation, and the secondary endpoint was PDAF ratio. If the patient avoided intubation, they were placed in the success group. If they ended up intubated, they were placed in the failure group. 11 of the 20 patients, so 55% in high-flow nasal cannula in prone position avoided intubation, and their overall PDAF ratio was improved compared to patients with non-invasive ventilation. And what this study tells me is that there's at least some evidence for using prone positioning and high-flow nasal cannula to avoid some of the more deleterious effects of intubation. So what if we take those data from Ding et al and apply them to COVID patients, i.e., can we use high-flow nasal cannula and prone positioning to avoid intubation? Well, this 2020 study from Hernandez-Romeo et al showed that mortality based on the timing of intubation and using retrospective data found that timing of intubation had no impact on mortality in contrast to the previous study. Of interest, though, is that about 50% of the patients were initially treated with high-flow nasal cannula, and of those, 28% did not require mechanical ventilation, and those 72% who were intubated did not have an increased mortality. It's unclear if any of the patients with high-flow nasal cannula were able to utilize prone positioning. So what exactly does all this mean? In my mind, it means that there's no harm in trialing high-flow nasal cannula in COVID-19 patients, and that it may actually help to avoid intubation. While high-flow nasal cannula and prone positioning was not the main focus of the Hernandez-Romeo study, the position study looked retrospectively at 105 non-intubated patients who were either prone or remained supine during their hospital stay. The primary endpoint was intubation, with secondary endpoints of mortality, timed intubation, and SpO2 to FiO2 ratio. The intubation rate was lower in prone patients, and the timed intubation was longer in prone patients, as demonstrated by the graph here on the left, being prone to positioning, and the blue being not prone to positioning. And then on the right here, looking at the probability of discharge, and you can see that prone positioning did have an impact on the probability of discharge, which was higher in prone patients versus non-prone patients. So the question now is, what are some of my personal thoughts and takeaways after reviewing this data and knowing what we've been doing at our institution? I think that awake proning and high-flow nasal cannula can delay or avoid intubation in these patients. I think, obviously, intubate patients, if they need to be intubated, I think refractory hypoxia with SpO2 less than 85%, increased work of breathing with respiratory rate consistently in the 30s and appearing to tire. Prior to intubation, placing central lines for arterial pressure monitoring. Important, really, to connect with family prior to intubating the patients, as this really may be the last time for them to tell their family members that they love them. Be skeptical, be flexible. Data changes fast, and we need to be up-to-date while remaining skeptical of different studies that are being published. These are just my references. I hope you all enjoyed this brief talk on high-flow nasal cannula and prone positioning in COVID ARDS. Thank you so much.

awake proning

high-flow nasal cannula

COVID-19 ARDS

self-proning

intubation avoidance