Single-Site Low-Flow Veno-Venous Extracorporeal Lung Support Does Not Influence Hemodynamic Monitoring by Transpulmonary Thermodilution

Hemodynamic monitoring in patients with venoarterial extracorporeal membrane oxygenation

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an effective mechanical circulatory support modality that rapidly restores systemic perfusion for circulatory failure in patients. Given the huge increase in VA-ECMO use, its optimal management depends on continuous and discrete hemodynamic monitoring. This article provides an overview of VA-ECMO pathophysiology, and the current state of the art in hemodynamic monitoring in patients with VA-ECMO.

Hemodynamic monitoring in the extracorporeal membrane oxygenation patient

PURPOSE OF REVIEW

Hemodynamic monitoring in ECMO patients requires familiarity with the underlying pathophysiology and circulatory mechanics of extracorporeal flow. This review discusses the various monitoring modalities relevant to the management of patients on venovenous ECMO (VV ECMO) and venoarterial (VA ECMO). We emphasize tools to judge the adequacy of perfusion, predict the response to fluid boluses, measure right ventricular function, assess left ventricular distention (for VA ECMO), and monitor the process of weaning from ECMO. We emphasize how differences between VV ECMO and VA ECMO are reflected in distinct approaches to monitoring.

RECENT FINDINGS

Point-of-care ultrasound and near-infrared spectroscopy can play a significant role in monitoring of global and regional perfusion.

SUMMARY

Recent literature in hemodynamic monitoring of ECMO patients is discussed, with comparison of VV ECMO and VA ECMO. Many common monitoring tools lack validity during ECMO: by taking into account the unique physiology of the ECMO circulation, selected methods can aid in the care of these complex patients.

Extravascular lung water measurements in acute respiratory distress syndrome: why, how, and when?

PURPOSE OF REVIEW

Increase in pulmonary vascular permeability accompanied with accumulation of excess extravascular lung water (EVLW) is the hallmark of acute respiratory distress syndrome (ARDS). Currently, EVLW and pulmonary vascular permeability index (PVPI) can be quantitatively measured using the transpulmonary thermodilution (TPTD) technique. We will clarify why, how, and when EVLW and PVPI measurements should be performed.

RECENT FINDINGS

Although the Berlin criteria of ARDS are simple and widely used, several criticisms of them have been published. The last 2 decades have witnessed the introduction and evolution of the TPTD technique for measuring EVLW and PVPI. Several publications have recommended to evaluate EVLW and the PVPI during the treatment of critically ill patients. Accurate and objective diagnoses can be made for ARDS patients using EVLW and PVPI. EVLW more than 10 ml/kg is a reasonable criterion for pulmonary edema, and EVLW more than 15 ml/kg for a severe condition. In addition to EVLW more than 10 mL/kg, PVPI more than three suggests increased vascular permeability (i.e., ARDS), and PVPI less than 2 represent normal vascular permeability (i.e., cardiogenic pulmonary edema).

SUMMARY

EVLW and PVPI measurement will open the door to future ARDS clinical practice and research, and have potential to be included in the future ARDS definition.