Reduction of Blood Recirculation in Veno-Venous ECMO

Study Overview
=================
Brief Summary
-----------------
Blood which recirculates through the circuit of a veno-venous Extracorporeal Membrane Oxygenation (V-V ECMO) does not contribute to the systemic oxygenation of a patient on V-V ECMO and is called the recirculation fraction (Rf). Theoretically, the optimization of ECMO blood flow is possible using Rf measurements. A prospective, observational study will be performed measuring the Rf of total ECMO blood flow in patients with acute respiratory distress syndrome (ARDS) on V-V ECMO with an ultrasound dilution technique. ECMO blood flow will be optimized by reducing ECMO blood flow in accordance with the measured Rf as long as systemic oxygenation is not compromised.

Detailed Description
-----------------
Based on data from the 'Blood Recirculation and vvECMO' trial (ClinicalTrials.gov ID: NCT03200314) (i.e. an expected frequency of successful blood flow reduction of 66.7%), using a one-sample Chi square test, a two-sided type-1 error of 5%, a power of 80%, a total of 68 patients is needed to show that the proportion of patients with a secure ECMO blood flow reduction is greater than 50%. Presumably, 136 Patients have to be included into the trial to study 68 patients with a relevant Rf since not all patients on V-V ECMO suffer from a high Rf.

Official Title
-----------------
Reduction of Blood Recirculation in Veno-Venous ECMO Through Ultrasound Dilution Measurements (ECMO Circulation Study)

Conditions
-----------------
Extracorporeal Membrane Oxygenation, Acute Respiratory Distress Syndrome

Participation Criteria
=================
Eligibility Criteria
-----------------
Patients aged 18 years or older requiring veno-venous ECMO for treatment of refractory hypoxemia in ARDS.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Successful ECMO blood flow reduction | Number of patients with a relevant recirculation fraction and successful ECMO blood flow reduction | Once within the first week after initiation of ECMO therapy | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recirculation fraction | Fraction of blood recirculating through the ECMO circuit | Once within the first week after initiation of ECMO therapy | 
| Arterial blood oxygen content | Arterial blood oxygen content before vs. after reduction of ECMO blood flow | Once within the first week after initiation of ECMO therapy | 
| Extracorporeal Blood Flow | ECMO Blood Flow before vs. after reduction of ECMO blood flow | Once within the first week after initiation of ECMO therapy | 
| srporeal Gas flow | ECMO Sweep Gas flow | Once within the first week after initiation of ECMO therapy | 
| Length of ECMO therapy | Days on ECMO | Daily until the end of ECMO therapy (approximately 14 days) | 
| Cannula position and distance | The distance between the tip of drainage and return cannula will be measured in the existing medical imaging (e.g. CT scans) | Once within the first week after initiation of ECMO therapy | 
| Right heart dysfunction | Existing echocardiography will be evaluated for possible right heart dysfunction | Once within the first week after initiation of ECMO therapy | 
| Length of mechanical ventilation | Length of mechanical ventilation | Entire duration of the ICU stay (approximately 28 days) | 
| Complications of ECMO therapy | Incidence of cannula or system changes (i.e. due to circuit clotting), complications attributed to ECMO therapy like bleeding complications from the cannulation site, transfusion requirements, hemolysis | Length of ECMO therapy (approximately 14 days) | 
| ICU mortality | ICU mortality | Entire duration of the ICU stay (approximately 28 days) | 
| ICU length of stay | ICU length of stay | Entire duration of the ICU stay (approximately 28 days) | 
| Incidence of ICU-acquired organ dysfunctions and complications | Cerebral-, cardiovascular-, cardiac- pulmonary-, gastrointestinal- and renal dysfunctions, ICU-acquired infections | Entire duration of the ICU stay (approximately 28 days) | 
| ECMO blood flow over time | ECMO blood and sweep gas flow over time | Daily until the end of ECMO therapy (approximately 14 days) | 
| ECMO sweep gas flow over time | ECMO sweep gas flow over time | Daily until the end of ECMO therapy (approximately 14 days) | 
| Mobility at ICU discharge | Level of mobility the patient has reached at ICU discharge (recumbent, sitting, standing, walking with help, walking independently) | Discharge from the ICU (approximately 28 days) | 
| Weaning level at ICU discharge | Level of weaning reached at ICU discharge | Discharge from the ICU (approximately 28 days) | 
| Status of mechanical ventilation at ICU discharge | Status of mechanical ventilation at ICU discharge including all relevant settings and parameters | Discharge from the ICU (approximately 28 days) | 
| Level of organ dysfunction at ICU discharge | Sepsis-related Organ Failure Assessment Score at ICU discharge | Discharge from the ICU (approximately 28 days) | 
| Level of consciousness at ICU discharge | Glasgow Coma Scale at ICU discharge | Discharge from the ICU (approximately 28 days) | 
| Level of disease severity | Acute Physiology And Chronic Health Evaluation at ICU discharge | Discharge from the ICU (approximately 28 days) |