Bedside troubleshooting during venovenous extracorporeal membrane oxygenation (ECMO)
In this review, we discuss common difficulties that clinicians may encounter while managing patients treated with venovenous (VV) extracorporeal membrane oxygenation (ECMO). ECMO is an increasingly important tool for managing severe respiratory failure that is refractory to conventional therapies. Its overall goal is to manage respiratory failure-induced hypoxemia and hypercarbia to allow “lung rest” and promote recovery. Typically, by the time VV-ECMO is initiated, the patient’s pulmonary condition requires conventional ventilator settings that are detrimental to lung recovery or that exceed the remaining functional lung’s ability to maintain acceptable physiological conditions. Standard mechanical ventilation can activate inflammation and worsen the pulmonary damage caused by the underlying disease, leading to ventilator-induced lung injury. In contrast, VV-ECMO facilitates lung-protective ventilation, decreasing further ventilator-induced lung injury and allowing lung recovery. Such lung-protective ventilation seeks to avoid barotrauma (by monitoring transpulmonary pressure), volutrauma (by reducing excessive tidal volume to promote lung rest), atelectotrauma [by maintaining adequate positive end-expiratory pressure (PEEP)], and oxygen toxicity (by decreasing ventilator oxygen levels when PEEP is adequate). ECMO for adult respiratory failure was associated with overall survival of 62% in 2018, according to the Extracorporeal Life Support Organization (ELSO) January 2019 registry report. Difficulties that may arise during VV-ECMO require timely diagnosis and optimal management to achieve the most favorable outcomes. These difficulties include ventilation issues, hypoxemia (especially as related to recirculation or low ECMO-flow-to-cardiac-output ratio), sepsis, malfunctioning critical circuit components, lack of clarity regarding optimal hemoglobin levels, hematological/anticoagulation complications, and right ventricular (RV) dysfunction. A culture of safety should be emphasized to optimize patient outcomes. A properly functioning team—not only the bedside clinician, but also nurses, perfusionists, respiratory therapists, physical therapists, pharmacists, nutritionists, and other medical specialists and allied health personnel—is vital for therapeutic success.