Leap of Faith

This post is a little tricky because I have only a basic grasp of the complex medical intricacies. It occurred several months ago so I don't have a perfect memory for the situation, but I wanted to write about it because it was pretty unique.

A patient has multiple complications after a routine cardiac surgery. He develops a severe pneumonia leading to acute respiratory distress syndrome. The infection stuns his already-weak heart, causing him to go into heart failure and even have a cardiac arrest. After resuscitation, he goes to the operating room for placement of a left ventricular assist device, a mechanical pump that aids the heart in pushing blood from the left ventricle into the aorta. The following day, his pneumonia worsens so much that his lung struggles to oxygenate the blood. Because of his respiratory failure, he goes to the operating room again for placement of veno-arterial ECMO. This artificial circuit takes blood out of the venous (right) side of the heart, pumps it through an oxygenator, and sends it back into the arterial (left) side of the body. By now, he has been in the hospital for almost a month struggling to recover after this complicated surgery.

I am covering for a few days on the cardiothoracic ICU service and when I meet him, he is dependent on ECMO and his LVAD. The majority of his blood is sucked out of the right side, oxygenated artificially, and sent back to the left side. What little blood goes through the native circulation gets pumped by his right heart to the left and assisted by the LVAD into the arterial circulation. His lungs are getting better; with supportive care, the infection is being treated and the inflammation suppressed. Tests of compliance - that is, how flexible the lungs are - show improvement. Indeed, since the ECMO circuit acts as artificial lungs, it allows us to rest his native lungs. However, while on the ECMO circuit, it is very hard to test the ability for the lungs to oxygenate the blood.

The problem is simply this. At some point, we will have to get the patient off ECMO. Once we think the lungs are better, the risks of continuing ECMO (bleeding, infection, strokes) will outweigh the benefits. But how do we get him off ECMO?

Every time we try to wean the ECMO circuit and send less blood through the artificial membrane and more to the right heart, the right heart shows signs of failure. During the pneumonia and concurrent inflammation, the right heart was quite strained; it's not used to pushing against a high resistance circuit. It then suffered quite a bit during the cardiac arrest. Now, it's so weak that it cannot push much blood to the left side. Hemodynamically, we're dependent on ECMO. However, this means we cannot test the lung's ability to oxygenate; we cannot send enough blood through the native heart to challenge the lungs.

The solution for the hemodynamic dilemma is to go to the operating room and place a right ventricular assist device or RVAD. This internal device helps push blood from the right ventricle to the lungs. However, when we do this, we would like to take the patient off ECMO. An RVAD would replace the hemodynamic function of ECMO but not its artificial oxygenator. Since we never tested the lungs for the recovery of oxygenation, this would be a leap of faith, assuming the patient's lungs had recovered enough to support life.

This was the dilemma. Each day we waited to place the RVAD and remove the ECMO, we gave the lung time to recover but incurred all the risks of ECMO and the ICU stay. However, there was no way to quantify the recovery and know for sure when to bite the bullet and go for it. All we had was clinical experience, indirect measurements, and a gestalt. At some point, we needed to take a leap of faith and hope that he would make it. After much consultation with the ICU team, pulmonary attending, ECMO expert, and cardiothoracic surgeons, we decided to go for it. Fortunately, he did fine.