with a blood pressure of 110/60 mm Hg and a normal lactate level. He has no signs of renal, hepatic, or neurologic injury. On transthoracic echocardiography, his left ventricular ejection fraction has improved from 10% on day 1 to 30% on day 2. His left ventricular size appears normal with no obvious valvular abnormalities. He has responded well to furosemide and his fluid balance is 3L negative since initiation of ECMO. His pulmonary capillary wedge pressure is 12 mm Hg. His chest x‐ray shows bilateral lower lobe infiltrates. However, his upper body peripheral oxygen PaO2 is 40 mm Hg despite maximal ARDSnet appropriate ventilator settings, while his lower body PaO2 remains > 200 mm Hg. What is the next best step in his management?Place a left ventricular microaxial percutaneous ventricular assist device for left ventricular venting.Increase total VA ECMO flows to improve upper body saturation.Add a second‐line inopressor in addition to epinephrine.Place a venous reinfusion ECMO cannula and convert the patient’s configuration to VA‐V ECMO.Perform an atrial septostomy for left ventricular unloading.Left ventricular venting is commonly employed in patients supported on peripheral VA ECMO when the native cardiac function is not robust enough to overcome the increased afterload generated by the VA ECMO circuit, which leads to left ventricular distention. This patient shows no signs of left ventricular distention with a normal PCWP, no signs of aortic or mitral insufficiency, and an improving ejection fraction. Performing LV decompression with a septostomy or mechanical device is likely unnecessary in this patient.There is no evidence of renal or hepatic impairment and cardiac function has improved, making an increase in cardiac output, especially to the lower body (whether increased arterial flow or increased inopressor support), unnecessary. Rather, this patient is likely suffering from severe respiratory failure from aspiration pneumonitis rather than left‐sided heart failure and pulmonary edema. While his lower body oxygen delivery is adequate, the oxygen delivery to the coronary and cerebral circulation is likely not, with a PaO2 of 40 mm Hg. Addition of a venous reinfusion limb to convert to a hybrid VA‐V ECMO circuit will provide additional oxygenation support and is the most useful next step.Answer: DRusso JJ, Aleksova N, Pitcher I, et al. Left ventricular unloading during extracorporeal membrane oxygenation in patients with cardiogenic shock. J Am Coll Cardiol. 2019; 73(6):654–662. doi: https://doi.org/10.1016/j.jacc.2018.10.085. PMID: 30765031.5 While on venovenous ECMO, which of the following ventilator strategies should be used to provide lung protection and recovery?Figure 3.1 VA‐V ECMO circuit.Source: From Biscotti M., Lee A,, Basner RC., et al. Hybrid configurations via percutaneous access for extracorporeal membrane oxygenation: a single‐center experience. ASAIO J. 2014;60(6):635–42. with permission.T‐piece or tracheostomy collarHigh‐frequency percussive ventilationHigh‐frequency oscillatory ventilationVolume control 8 mL/kg ideal body weightPressure control with PEEP of 10 cm H20Lung protective ventilation should continue after ECMO initiation. In fact, so‐called ultra‐lung protective ventilation is often feasible once the majority of the patient’s gas exchange needs are provided by the ECMO circuit. The best current approach is likely reflected in the recently conducted EOLIA trial in which plateau airway pressure was limited to a maximum of 24 cm H2O in conjunction with PEEP > = 10 cm H2O (corresponding to a driving pressure < = 14 cm H2O), respiratory rate of 10–30 breaths/min, and FiO2 of 0.3–0.5. This can be achieved with either a volume control or a pressure control mode, but in our view, a pressure control mode is easier to apply in the setting of very low lung compliance. Often the tidal volumes will be much lower than 4 mL/kg, especially early after ECMO initiation. Furthermore, the respiratory rate should be minimized to further decrease ventilator‐induced lung injury.Early after ECMO initiation, patients may have significant air hunger and may also need moderate‐to‐deep sedation for a period of time. As a result, spontaneous modes of ventilation are not employed until the patient has shown some signs of stabilization or even recovery. High‐frequency percussive ventilation can help with mobilizing secretions, particular in patients with inhalation injury, but this approach is not routinely used in ECMO patients. High‐frequency oscillatory ventilation has no proven benefit in this population and may actually cause harm in some cases. Finally, volume control ventilation at this level typically results in extremely high driving pressures, especially early after ECMO initiation.Answer: EAbrams D, Schmidt M, Pham T, et al. Mechanical ventilation for acute respiratory distress syndrome during extracorporeal life support. Research and practice. Am J Respir Crit Care Med. 2020; 201(5):514–525. doi: https://doi.org/10.1164/rccm.201907‐1283CI. PMID: 31726013.Brodie D, Bacchetta M . Extracorporeal membrane oxygenation for ARDS in adults. N Engl J Med. 2011; 365(20):1905–14. doi: https://doi.org/10.1056/NEJMct1103720. PMID: 22087681.ELSO Guidelines for Cardiopulmonary Extracorporeal Life Support (2017). Extracorporeal Life Support Organization, Version 1. https://www.elso.org/Portals/0/ELSO%20Guidelines%20For%20Adult%20Respiratory%20Failure%201_4.pdf (accessed 4 August 2017).
6 A 30‐year‐old previously healthy man is placed on venovenous (VV) ECMO for severe COVID‐19 pneumonia. On ECMO day 5, he is intubated but awake and interactive on minimal sedation. His morning chest x‐ray demonstrates a new right‐sided pneumothorax. After insertion of a tube thoracostomy, he continues to have a large, continuous air leak on ECMO day 7. His pulmonary compliance remains moderate‐to‐high, with a tidal volume of 7 mL/kg IBW on a positive end‐expiratory pressure (PEEP) of 5, a driving pressure of 10 cm H2O, a fraction of inspired oxygen (FiO2) of 0.5, and a respiratory rate of 20 breaths/min. He remains on ECMO support with a sweep gas flow rate of 6 liters/min. His peripheral arterial blood gas shows a pH of 7.36, PaCO2 of 47, and a PaO2 of 78. What is the best management approach for this patient’s mechanical ventilation?Extubate to high flow nasal cannula.Increase PEEP.Convert to airway pressure release ventilation (APRV) with a PHI of 30 and PLOW of 0.Sedate, paralyze, and prone positioning.Increase tidal volumes.This patient has a persistent continuous air leak, which can be exacerbated by continuous positive pressure ventilation. Ventilator strategies to aid in healing of bronchopleural fistulae typically include lowering airway pressures and PEEP. Strategies that include increasing PEEP, tidal volumes, or APRV can lead to higher airway pressures, which may preclude lung healing. In select cases, extubation may be a reasonable strategy, provided the patient can be sufficiently supported without tracheal intubation.Answer: AXia J, Gu S., Li M,s et al. Spontaneous breathing in patients with severe acute respiratory distress syndrome receiving prolonged extracorporeal membrane oxygenation. BMC Pulm Med. (2019); 19 : 237. https://doi.org/10.1186/s12890‐019‐1016‐2
7 After initiating venovenous ECMO, which strategy is most likely to minimize bleeding while also preventing clot formation in the circuit or around the cannulas?Heparin bolus and infusionLow molecular weight heparin 1.5 mg/kg twice dailyArgatroban infusionDual antiplatelet therapyWithholding systemic anticoagulation for 24 hoursBlood exposure to the surface of the gas exchange membrane and the circuit activates the intrinsic clotting cascade, the complement system, and platelets. This results in a state of both hyper‐ and hypo‐coagulation. In some cases such as a recent intracranial bleed or solid organ injury, patients on venovenous ECMO may have anticoagulation withheld. However, in most cases, low‐dose anticoagulation is used to preserve the gas exchange membrane’s efficiency, increase the circuit longevity, and mitigate the risk of thromboembolic complications. Patients on veno‐arterial ECMO are generally maintained on higher doses of anticoagulation given the more significant implications of an arterial thromboembolic event.The most common anticoagulation approach is a heparin bolus upon cannula insertion (50–100 units/kg) followed by a continuous heparin infusion (7.5‐20 units/kg/hr). Heparin titration has historically been performed based on activated clotting time (ACT) measured at the bedside (target 180–220 seconds); however, recent evidence suggests that either a PTT‐based approach (1.5‐2 times baseline) or an anti‐Xa approach (0.25 units/mL) may be preferable.Therapeutic low molecular weight injections are not typically performed on ECMO. Argatroban, a direct thrombin inhibitor, can be used but is generally reserved for patients with a history of, or concern for, HITT. Withholding anticoagulation can be done as described above, and some evidence suggests
