ECMO |The patient wasn’t one you’d expect would be brought to death’s door by lung disease but he was saved by ECMO.
Victor Carlos, 41, had been healthy and in good enough shape to run three marathons. But in December he arrived at the Emergency Department at University of Colorado Hospital in severe respiratory distress. Providers intubated him, then put him on a ventilator. Nothing was working.
“His lungs couldn’t get the carbon dioxide out or the oxygen into his blood,” said UCH cardiothoracic surgeon Ashok Babu, MD. “He was going into multiple organ failure and was nearing death.”
Babu came to the hospital after receiving an urgent call from the pulmonologists treating Carlos, Katherine Vandervest and Abigail Lara. Babu and the pulmonologists decided to try a last-ditch, lifesaving effort: extracorporeal membrane oxygenation, or ECMO.
In simple terms, they would use a cannula and tubes – inserted through the jugular vein in the neck – and an external mechanical pump system to suck blood out of the veins, oxygenate it, remove carbon dioxide and return it to the heart for circulation to Carlos’s dying organs. The system would do the work for his badly injured lungs until they could recover.
“The ECMO immediately took over the work of the lungs and slowly brought his organs back to life,” Babu said.
But the procedure provided no short-term cure. Carlos would need four weeks of ECMO support before his lungs healed sufficiently to work on their own.
“The key is ECMO allows us to safely provide prolonged support,” Babu said. And without having to rely on a mechanical ventilator for primary support, patients can get up and move sooner, a key to faster recovery.
Carlos is one of seven patients the hospital has treated with ECMO since July 1, 2012, Babu said, a small increase from the previous year. He envisions developing a protocol for administering it as well as specialized nursing training in the procedure.
Although UCH is the only hospital in the state equipped to use ECMO to treat patients with severe pulmonary injury and disease, Babu worries that not enough community providers in the state or region are aware that the lifesaving procedure is available. “It’s great technology, and I have no doubt that patients in Colorado are dying without it,” he said.
Carlos, who last week moved from the hospital’s Cardiology Unit to Rehabilitation Medicine, where he will get physical and occupation therapy, was felled by acute respiratory distress syndrome (ARDS) that began as an influenza infection and progressed to pneumonia and ultimately respiratory failure. His strong heart and otherwise healthy condition made him a good candidate for ECMO, Babu said.
“It’s a big insult to the body. Patients must be in relatively good health so they have strong physical reserves,” he explained. The procedure therefore is not appropriate for patients with pre-existing pulmonary disease unless they are awaiting lung transplant. Patients over 70 and those with severe complications, such as disease in other organs, are not good candidates for ECMO, Babu said.
But in the right patient, ECMO has sustained patients for as long as four months, he added. Unlike a ventilator, the process doesn’t involve forcing air into the lungs, which can distend and further damage delicate aveoli, the tiny air sacs where blood gas exchange occurs.
Clinicians use the ECMO machine in two different ways. Because Carlos needed only lung support, Babu tapped into the venous system (the venovenous, or VV, technique). In Carlos’s case he used a single-site cannula with two lumens (tubes) that drew “blue” deoxygenated blood into the ECMO machine to be oxygenated, filtered, warmed, and returned, bright red, to the heart for circulation.
For patients who need both cardiac and pulmonary support, providers tap a vein and an artery (the venoarterial, or VA, technique). After blood taken from the vein is oxygenated, the machine returns it to an artery with additional pressure to assist the left ventricle of the heart in pumping the blood to the rest of the body.
The ECMO procedure is not without challenge and risk, Babu emphasized. In addition to the equipment and the know-how to operate it, a hospital must have a large, multidisciplinary team, including surgeons, pulmonologists, respiratory therapists, perfusionists and skilled critical-care nurses. The blood bank also plays a key role, as patients may require multiple transfusions.
Inserting the cannulas increases the risk of infection, Babu said, but the most common problem in ECMO is bleeding. The “trauma” of being spun and oxygenated, he explained, may damage platelets, decreasing the blood’s ability to clot. In addition, patients receive heparin, a blood thinner, as part of the treatment, further increasing the risk of bleeding. Physicians must be alert and stop administering heparin at the first sign of bleeding, Babu said.
Another barrier to more widespread adoption of ECMO is disagreement in the medical community about its effectiveness. Trials in the 1990s, Babu said, compared survival rates in ARDS patients treated with VV ECMO with those sustained on mechanical ventilation. The trial was inconclusive.
A 2009 randomized study in the United Kingdom conducted around the time of the H1N1 influenza pandemic revived interest in VV ECMO, Babu said. But although the results showed ECMO improved survival rates in ARDS patients, the study had several flaws, which has led some to minimize its significance.
However, more substantive evidence could come from a new, randomized trial based in a Paris hospital. The trial, dubbed EOLIA, again compares morbidity and mortality rates in ARDS patients treated with ECMO with those sustained with mechanical ventilation and medical management.
The EOLIA study is scheduled to finish next January. All Victor Carlos knows is he’s alive now after a long nightmare. “I’m still weak as a kitten,” he said from his hospital bed last week. “But I’m working toward being able to go home.”