Semiquantification of Systemic Venous Admixture During Venovenous Extracorporeal Oxygenation Via Bicaval Double-Lumen Cannula in Critically Ill Patients.

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is increasingly utilized in acute reversible cases of severe respiratory failure and as a bridge to lung transplantation. Venovenous extracorporeal membrane oxygenation using a bicaval double-lumen cannula (BCDLC) has several advantages over the traditional ECMO configuration; however, it also presents with several unique challenges. The assessment and quantification of venous admixture is difficult due to the specific position of BCDLC within the circulatory system. We describe the nature of the double-lumen bicaval venovenous ECMO cannula and relevant specific issues associated with monitoring complex details of oxygenation within different parts of circulation, including existing barriers for quantification of recirculation and venous admix. New conceptual approach to the quantification of venous admix is described. Right side echocardiographic contrast, when sequentially injected in separate superior vena cava (SVC) and inferior vena cava (IVC) venous basins, bypasses drainage ports of the catheter in double-lumen bicaval VV-ECMO configuration together with deoxygenated returning from the periphery venous blood. It was easily detectable entering right heart chambers by two- and three-dimensional echocardiography. Amount of bubbles from the agitated fluid contrast within right atrium indicates relative amount of venous admixture in relation to the returning from the oxygenator blood which is bubble free.

Ejection fraction - A number to be interpreted with caution!

Cardiogenic shock is frequently seen following acute myocardial infarction complicated by the rupture of interventricular septum and formation of functional ventricular septal defect. Despite significant advances in medical, interventional and surgical management, the mortality in this group of patients remains very high. We present a case of refractory cardiogenic shock following an exclusion bovine pericardial patch repair of post infarction ventricular septal defect, where the residual functional left ventricular cavity size was insufficient to maintain end organ function. This case illustrates the concept of "Normal ejection fraction low cardiac output cardiogenic shock", where reporting left ventricular ejection fraction number in isolation can be misleading.

Right ventricular loop indicating malposition of J-wire introducer for double lumen bicaval venovenous extracorporeal membrane oxygenation (VV ECMO) cannula.

The key to safe placement of a bicaval double lumen cannula for Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) is to visualise correct guide wire placement in the inferior vena cava (IVC), thus aiding subsequent correct advancement of the cannula. Transoesophageal (TOE) and transthoracic (TTE) echocardiography, as well as fluoroscopy, have been described as aiding imaging techniques. We report a case of guide wire malposition into the right ventricle, despite echocardiographic confirmation of guide wire position deep into the IVC. This malposition, if undetected, may have resulted in potential life threatening complications.

Malposition of Double Lumen Bicaval Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) cannula resulting in hepatic venous congestion.

Introduction: Optimal positioning of double lumen bicaval canula for extracorporeal membrane oxygenation (ECMO) support used as a rescue measure in refractory hypoxaemia is essential to facilitate adequate oxygenation, prevent recirculation and avoid complications. Method: Echocardiography via transoesophageal or transthoracic windows can be used as guidance and as a surveillance technique to prevent cannula malposition. We describe a case of Double-Lumen Bicaval VV ECMO cannula malposition leading to a massive retrograde hepatic venous flow. Conclusion: Rapid echocardiographic diagnosis was pivotal in preventing potentially fatal complications.