Physicians at Princeton Medical Center have repurposed a therapy that has been used for years to support oxygen levels in patients with severe lung disease. Recently, extracorporeal membrane oxygenation (ECMO) has been used in the treatment of COVID-19 patients at the hospital with much success.
"In the past, we have used ECMO for flu patients and we usually reserve the ECMO machines for people who are so sick that even maximal support can't maintain viable oxygen levels," says interventional cardiologist Rayan Saab, MD, with Cardiology PC, an affiliated practice of Princeton. "With veno-venous ECMO, blood is not taken from a vein and put into an artery. Instead, it is taken out of a vein and put back into a vein after it circulates and loads the blood with oxygen. After reading about different cannulation strategies, we implemented an approach that minimized trauma to patients' lungs, which is caused by the ventilator. We put them on ECMO and extubated them."
To use the ECMO, a cannula with two openings is placed in the patient's neck. One cannula takes blood out of the body and the other puts it back. The tip of the cannula ends in the lung artery preventing backflow and mixing the highly oxygenated blood with blood with low oxygen levels. "The valves on the right side of the heart prevent backflow, so there is no mixing of blood," Saab says. "That way, the heart circulates highly oxygenated blood to the patient's body with less mixing.
"These patients were awake, talking and walking and basically breathing on their own with the help of ECMO. They had severe COVID-19 pneumonia, but they didn't have trauma to their lungs like they would if they were on a breathing machine. We were able to help several patients with severe cases.
"COVID pneumonia is bad. The lungs are filled with inflammatory fluid. Although the patients have good oxygen levels, while on ECMO they might feel like they are drowning. For comfort, we put them back on the breathing machine until their lungs begin to clear. Overall, it was a successful strategy. We were able to avoid tracheostomies and feeding tubes for most of our patients."
There can be long-term effects from COVID-19, but Saab says using the ECMO is greatly beneficial. "Obviously, you can have complications from the ECMO access site or a clot forming in a vein," he says. "We've had a few of those, but we had no infections related to the cannula and never had any problem with massive bleeding. These patients have a tendency to bleed, because they are on blood thinners while they are on ECMO. We've had patients bleed from their lungs, oral airway and GI tube, but we rarely see bleeding from the cannula sites because they are controlled."
One-on-one monitoring was another successful strategy in caring for these patients. They were monitored around the clock. "Blood is drawn on an hourly basis, and adjustments are made
according to the ECMO settings," Saab says. "Our nurses do a phenomenal job of keeping up with all the patients' needs while also communicating with their families. We are basically on call for these patients around the clock."
Overall, the Princeton team has had great results with ECMO, considering how sick the patients are. "Even with working with the most severe form of COVID-19, we have a mortality rate at Princeton of about 30 percent," Saab says. "The national average of COVID- 19 patients requiring ECMO was closer to 50 percent, including major regional hospitals. Overall, our patients had more comorbidities than the national average, but most patients on ECMO have done well."
Saab believes many people are looking to Princeton Hospital as the place to send patients for ECMO. "We take every patient into consideration, although there are many patients who wouldn't qualify for different reasons," he says. "I think this positive experience with severely ill COVID patients can be extended to many other diseases that cause respiratory failure and acute respiratory distress syndrome.
"We still have a lot to learn, but this experience has given us a lot to think about. We have a team approach, and it has been a great success. I believe this can prepare us to better handle similar processes for other viruses and diseases down the road."