Patient survives for 48 hours with artificial lungs

A 33-year-old man survived without his lungs for 48 hours through the use of an external artificial-lung system until he could receive a double lung transplant.

The system was designed by Ankit Bharat, a thoracic surgeon at Northwestern University Feinberg School of Medicine in Chicago, and his team. The team published their findings in Med.

The patient had acute respiratory distress syndrome, a life-threatening condition in which the lungs cannot absorb enough oxygen, triggered by the influenza virus. The patient was placed on a ventilator, but developed a drug-resistant Pseudomonas aeruginosa infection, which caused his lungs to liquify. The man went into septic shock, and his heart and kidneys began to fail, making him too sick to undergo the necessary double lung transplant.

The medical team decided to remove his lungs, the source of the infection, and place him on an artificial lung system. His condition began to improve, and within 48 hours, his kidney and heart function were restored. At this point, the patient was able to receive the double lung transplant. Almost three years later, he has shown no signs of organ rejection or impaired lung function.

Creating artificial, external lungs

The artificial lung system features a flow-adaptive shunt that compensates for the loss of the lungs’ blood vessel network and dual pathways to drain blood from the body and return oxygenated blood to the heart.

With the total artificial lung (TAL) system, deoxygenated blood that would normally go to the lungs is drained from the body and passed through an external oxygenator where oxygen is added and carbon dioxide is removed through a membrane.

As well as the challenge of creating artificial lungs that could support a human life, the team had to solve the problem of the empty chest cavity, which could allow the heart to shift. To solve this problem, the team used temporary internal supports, including saline-filled tissue expanders (commonly used as breast implants), to stabilize the heart’s position until the lung transplant could occur.

Extracorporeal membrane oxygenation versus total artificial lungs

Extracorporeal membrane oxygenation (ECMO), used in situations where the heart and/or lungs are failing but are expected to recover, can oxygenate the blood and remove carbon dioxide while the person’s lungs are in the body, keeping the heart stable. In contrast, the new system is connected to the heart and maintains the right pressure for blood to flow to and from the heart. This allows the system to run when the lungs are removed.

The key element that differentiates this system from ECMO and other predecessors is the flow-adaptive shunt that compensates for the loss of the lungs’ blood vessel network. This allowed the system to automatically adjust to changes in how much blood the heart was pumping, maintaining balanced blood pressure into and out of the heart.

The TAL system is different from ECMO in a few key ways. ECMO cannot maintain blood circulation through the heart in the absence of both lungs, meaning the heart cannot function normally. In contrast, TAL can replace the network of blood vessels in the lungs as well as the breathing function when both lungs are absent.

The Northwestern team’s innovation created a complete circulatory loop that mimicked the function of the lungs, not only breathing but also connecting the left and right sides of the heart. The flow-adaptive shunt also allowed the system to adapt to the patient’s physiology rather than working at a fixed rate.