 Good morning everyone my name is Sri Karthik Valluri. I'm an assistant professor of medicine at Baylor College of Medicine. I specialize in critical care medicine and work in the cardiovascular transplant and mechanical circulatory support ICU here at Baylor St. Luke's Medical Center. Today I'm going to be talking about VV ECMO management and the transition to lung transplantation. I have no disclosures, no conflicts of interest and stage lung diseases such as COPD, ILD, cystic fibrosis and various others that cause ARDS ultimately will lead to mechanical ventilation if medical therapy fails. So following mechanical ventilation these patients will ultimately require a lung transplant to survive. From 1988 where there were 33 lung transplants in the United States to the 2020 and 2021 years where there are over 2,500. Globally from 2010 to 2018 around 34,000 lung transplants have taken place. As the number of transplants have increased there's been a high demand but unfortunately a low supply and during this time patients wait for a lung transplant. Now this led to weightless mortality. Variable causes of weightless mortality were there based on what the specific disease process was. So these patients after mechanical ventilation were slowly shifted over to VV ECMO as a means to support their respiratory requirements. VV ECMO utilization over the years. In 1972 Hill et al utilized it for cardiopulmonary failure and it was successful. Following which a study by Veith showed that ECMO could be used as a bridge to transplantation. However since then the survivability ratios and the percentages dropped off so it was not favored as much. In 2009 the H1N1 pandemic showcased the utility and the benefits of VenoVenus ECMO. There showed a 21% mortality in one of the studies. Cesar trial happened in 2009. 60% survived to six months without disability. These are the patients on ECMO. More studies in 2011 about H1N1 and finally Aeolia came out which didn't really show that much benefit over regular mechanical ventilation. However time happened and we had the 2019 COVID pandemic which showcased the utility of VV ECMO for the patients with severe ARDS. And as you can see the numbers of VV ECMO over time have progressively increased. To now the patients on VV ECMO and they're not getting better. The only option we have now is lung transplantation. So how are these lungs allocated? Originally they were based on the waiting time requirement of the patient, a post-transplant survival score and ECMO patients in the past would have increased wait times and more and more complications eventually not receiving lung transplant. However in May 4, 2005 the lung allocation score was developed and this allocation was determined by urgency and the patients on ECMO were considered higher acuity and prioritized to receive lung transplantations. From 1987 to 2013 there had been a progressive increase in the utilization of VV ECMO as a bridge to transplantation. So how do these patients who were bridged to transplantation with VV ECMO do? Several center studies have showed benefit compared to patients who were not bridged with VV ECMO and this trend has progressively increased and maintained its survival percentage one year after transplant. Most recently in 2019 three papers which showed a benefit and in our institution we practice this. Now we know about the stats the numbers and the benefits of bridging to transplant with VV ECMO. Let's talk about the management of these patients as they wait for these transplants. The prime directive of an intensivist in a transplant ICU and the clinical care team associated with these patients is to optimize and maintain the patient to remain a high priority for lung transplantation. When we're in these units thousands of bits of clinical information need to be processed in a rapid manner. The entire dynamic of a transplant ICU is determined and based on by a multidisciplinary approach to taking care of these patients. The team is comprised of perfusionists, nursing, respiratory therapy, physical therapists, dieticians, wound care specialists, the cardiothoracic surgeons who do the transplants and the transplant pulmonologists who maintain these patients, interventional cardiologists who are possibly essential for cannulation, intensivists and our clinical extenders and numerous amount of consultants as needed such as nephrology, infectious diseases, endocrinology, etc. Management of these patients is based on two things managing the machine and managing the patient. Managing the machine. There are several aspects that we look at when it comes to the machine and this is where the perfusionists are crucial, cannular management, cannular placement issues, oxygenator and sweep monitoring, looking for clots, etc. Circuit and flow monitoring, anticoagulation monitoring. Is it running? Is it appropriate? Do you have any issues with the system and the circuit? Hemodynamic monitoring as well. Complication monitoring such as chattering. Is there a volume issue or is there a suckdown? Recirculation. Are the cannulas appropriately positioned and temperature regulation? There are various strategies of cannulation, femrofemoral, femorrhojugular and most essential is this dual lumen cannula because that allows us to make the patient ambulate which has been shown to have a major benefit in the outcomes. Managing the machine entails a detailed review and constant vigilance by our perfusionists. When we round on these patients that's when they give us their feedback and their input and recommendations which helps us make some of these decisions. Managing the patient. Every physiological aspect of the patient must be considered as they await long transplantation. The psychological condition. These patients are prone to anxiety, depression, PTSD, anxiety because they're in this situation, the cannulation, the medical management, waiting, depression because of their situation and PTSD because of all of the possible clinical scenarios they might have faced such as the cannulation, possible hypoxia, the inability to breathe. So we must consider consultation psychiatry and the medications we choose should be appropriate to maintain the level of activity and make sure that the patient is always alert, awake. From the neurological standpoint it's about sedation. Initially when they're cannulated the patient will be deeply sedated. There should be light anesthesia to avoid spontaneous breathing and risk for air embolisms, post cannulation and reduce the metabolic rate and avoid movement. On day two spontaneous awakening trial should take place and we should do our neuro checks and by day two or three after stabilization on the VVACMOS circuit we need to start weeding these patients. Fontaneous breathing and early mobilization are the most crucial and essential aspects of the care of a patient who's bridging to transplantation on VVACMOS. So spontaneous breathing and early mobilization reduces isomyopathy, improves functional recovery, reduces secondary infections, reduces the length of stay, the cost of treatment and it also shows improved outcomes through multiple studies I've taken a look at this. This is one of our mobilized patients in our unit and as you see we have our physical therapists, our perfusionists and even our respiratory tech and of course the patient. Other aspects we look at for managing the patient is maintaining their volumes. Initiating the VVACMOS circuit we prime them with normal saline, we dilute the overall blood and increase the chistulate component of plasma and this could lead to third spacing in DEMA. So our goal here is to maintain the blood volume, keep the right atrial pressure around five to ten to CVP, maintain the normal hematocrit as well because that reflects in our oxygen carrying capacity. So we keep checking our hemoglobin and try to maintain it above seven. Body weight, we try to avoid volume overload because of the acute inflammatory status capillary leak into the extracellular fluid in the first 12 hours. Our goal here is to return them to their normal dry weight and we can utilize diuretics judiciously or CRT if needed, try to avoid that and then we keep checking perfusion parameters such as lactic acid and SVO2. The best ways to monitor strict input and output and daily weight is essential. Cardiovascular, it's about the complication watch. We have to look out for RV failure, look at the CVP so they're going up, look for pulmonary hypertension, is there PA pressure going up and refractory hypoxemia even on VVACMO which can determine a lot of aspects. Such as either recirculation, malpositioning the cannula or worsening respiratory function. Hemodynamic instability, we do not like to see that in these patients as they wait for their transplant because it can it can protract from our overall course and in order to maintain stability we need to make sure their cardiac output is appropriately managed. Look at their heart rate. This is something we can control and will help us with our ECMO flows and our ECMO dependency. Is the heart rate caused by anxiety or is it caused by physiological issues? Consider using esmalol or beta blocker if their blood pressure can tolerate it to adjust the heart rate and we also adjust the sedation. Shock is another thing we look for. It's very bad. You have to treat the underlying cause and this shock can be caused by various things. You have to look for septic shock. Source of sepsis could be the cannulation sites, could be a skin lesion, could be a worsening pneumonia, a secondary infection from developing. Is it cardiogenic? Is the RV giving up? Is the LV giving up? These are the constant assessments we need to make sure we do on these patients. We do a bedside echo or a formal echo to make sure in case we suspect any of these things happening. From the respiratory standpoint, monitor and look for pneumonias. We do this with chest x-rays, pneumothorax. We do this with chest x-rays daily. If the patient is ventilated, it is very essential that they have lung protective strategies to prevent ventilator induced lung injury. So overall, we want to keep a low, low vent settings and the recommendation on average based on ELSO European Network Caesar and Iolia is 30, 30, 10, 10. Title volume 4 to 6 liters per kg ideal body weight, FIO 30%. The plateau pressure should be less than 30. PEEP should be 10. Respiratory rate should be 10. The goal PAO2 on these patients on the ABG should be above 50. We're okay with that. And the goal SPO2, which is above 88%, we're okay. The ultimate goal here is to try and wean the ECMO dependency if possible. The renal, electrike management. Look for AKI, nephrotoxicity by the medications we're giving them. Look for congested nephropathy in case the patient is either volume overloaded or right ventricular failure. In worst case scenario, do we need to utilize CRRT? Replacing electrolytes is essential renal function monitoring. We do that with our labs, our VMP creatinine, urine output, urine color is a clinical parameter. If AKI or renal failure does occur, we can attach the CRRT machine to the ECMO circuit directly. The hepatic function. Look at the LFTs. Make sure there's no congestive hepatopathy. Make sure we're not causing any type of drug-induced liver injury. These are essential to look at. Constant monitoring. GI and nutritional requirements. Is the patient having bowel movements? Is there an ileus? Is there an absorption issue? Chloric requirements via tube feeds are delivered, but they're essential to monitor. And the caloric requirements are maintained and looked at and monitored by our dieticians. Triglyceride levels are also important to look for in these patients, especially if they're on propofol for an extended period of time. Endocrinopathies. Glucose control is essential in these patients. Always keep an eye out for adrenal insufficiency if you have a variable blood pressure on these patients. And also make sure that they have no pre-existing thyroid conditions. So from the hematological standpoint, it's ultimately a cytopenia watch. Look for anemia, leukocytosis, leukopenia, thrombocytopenia and coagulopathy. Anemia in case of blood loss or chronic illness. Leucocytosis or leukopenia setting of sepsis. Thromocytopenia is in case of heparin-induced antibodies. And then coagulopathies for various things from DIC to bleeding to extreme clotting. And ultimately monitoring anticoagulation, whether we do it from heparin or bival. One of the key factors of this is ECMO-induced coagulopathy. It's a vicious cycle of ECMO-circuit blood interaction, inflammation, thrombogeneration, hemolysis or clotting. So this is something that needs to be constantly monitored, which is done via our nursing staff, via our perfusionists, via our pharmacists, etc. Another essential aspect of managing these patients is to always look out for sepsis. The goal is to prevent it in all cases. However, potential sources of sepsis include lines, cannula sites, skin lesions, pneumonias, superimposed. This needs to be constantly watched. Cannulation sites need to be cleaned extensively. There's device prophylaxis antibiotics that are usually paced on these patients. There's no standard policy, but it's very institutional based. The vancomycin, much levels in troughs, doxycycline, minocycline, these are the agents we use. Watch for sepsis in this patient population. There's always an ambiguous presentation. It's a distributive shock, right? So it could be vasoplegic. It could be septic. We don't know. Always err on the side of sepsis in these patients because that can truly, truly harm the patient's outcome in this setting. So where do we go from here? There are a lot of developments in technology. Low resistance gas membranes, high durability centrifugal blood pumps, heparin-coated tubing, improved cannulation strategies, and there's new devices like McKett, like McKett's cardio help, abiomed's breathe machine, which allow patients to mobilize easier. So all of these things need to come together in an optimal fashion. And when they do, we can watch the patients that we all care for go into the OR and get a lung transplantation. The future is bright for this field and most importantly for our patients. Thank you all.