Surgical Critical Care and Emergency Surgery. Группа авторов

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 this may actually be safe for the entirety of a short ECMO run. However, this is not currently a standard approach. Likewise, dual antiplatelet therapy (DAPT) alone is not a standard approach although it may be used in patients with other indications for DAPT, which is more common in patients on veno‐arterial ECMO.Answer: AELSO Anticoagulation Guidelines (2017). Extracorporeal Life Support Organization, Version 2014. https://www.elso.org/portals/0/files/elsoanticoagulationguideline8‐2014‐table‐contents.pdf (accessed 30 July 2021).Kurihara C, Walter JM, Karim A, et al. Feasibility of venovenous extracorporeal membrane oxygenation without systemic anticoagulation. Ann Thorac Surg. 2020; 110(4):1209–1215. doi: https://doi.org/10.1016/j.athoracsur.2020.02.011. Epub 2020 Mar 12. PMID: 32173339; PMCID: PMC7486253.Parker RI . Anticoagulation monitoring during extracorporeal membrane oxygenation: continuing progress. Crit Care Med. 2020; 48(12):1920–1921. doi: https://doi.org/10.1097/CCM.0000000000004635. PMID: 33255117.Vandenbriele C, Vanassche T, Price S . Why we need safer anticoagulant strategies for patients on short‐term percutaneous mechanical circulatory support. Intensive Care Med. 2020; 46(4):771–774. doi: https://doi.org/10.1007/s00134‐019‐05897‐3. Epub 2020 Jan 23. PMID: 31974917.

      8 Since the inception of ECMO technology in the 1970s, the rates of bleeding and thrombotic complications have decreased significantly, though they remain a significant cause of morbidity and mortality. Which factor is likely the most significant contributor to the observed decrease in bleeding and thrombotic complications over the past several decades?Novel anticoagulants including direct thrombin inhibitorsChanges in ECMO device technologies The invention and use of thromboelastographyMore accurate assays for activated clotting time and activated partial thromboplastin timeDiscovery of modern‐day antiplatelet therapyThe use of novel anticoagulants and antiplatelet therapies in ECMO has been described but has not been studied sufficiently to make any recommendations for or against their use.Use of TEG and ACT monitors, as well as protocols targeting low or high PTT goals, is often implemented; however, current evidence is insufficient to recommend one specific approach over the others. The improvements in ECMO circuit technology and heparin‐coated cannulas have likely led to a decrease in total dose and duration of anticoagulation required and an improvement in circuit‐related hemorrhagic or thrombotic complications.Answer: BSklar MC, Sy E, Lequier L, et al. Anticoagulation practices during venovenous extracorporeal membrane oxygenation for respiratory failure. A systematic review. Ann Am Thorac Soc. 2016; 13(12):2242–2250. doi: https://doi.org/10.1513/AnnalsATS.201605‐364SR. PMID: 27690525.

      9 Acute kidney injury (AKI) is a common problem in patients requiring ECMO therapy. As such, the use of renal replacement therapy (RRT) is necessary in 40–60% of cases. Which of the following statements regarding use of RRT and ECMO is most accurate?RRT access should never be provided via an in‐line approach with ECMO circuits. It should always be provided via separate vascular access.Fluid overload is an uncommon problem in the pediatric ECMO population and has no significant effect on morbidity and mortality.Uremia and electrolyte derangements are the most common indications for RRT initiation in both children and adults on ECMO.The polymethylpentene oxygenator used in ECMO circuits can also be used as a hemofilter to deliver RRT in patients with concomitant AKI.Negative fluid balance on RRT is independently associated with improved outcomes for both the adult and pediatric ECMO population.The most common indication for RRT in both adult and pediatric ECMO patients is fluid overload. Specifically, in the pediatric population, fluid overload is associated with increased mortality and longer duration of ECMO support. Further, several studies have associated a net negative fluid balance while on RRT with improved patient outcomes.It is safe and feasible to provide RRT via either separate vascular access or direct integration into the ECMO circuit, depending on patient‐specific circumstances. However, the polymethylpentene oxygenator will provide gas exchange but will not function as a hemofilter to provide RRT.Answer: EOstermann M, Connor M Jr, Kashani K . Continuous renal replacement therapy during extracorporeal membrane oxygenation: why, when and how? Curr Opin Crit Care. 2018; 24(6):493–503. doi: https://doi.org/10.1097/MCC.0000000000000559. PMID: 30325343.Gorga SM, Sahay RD, Askenazi DJ,et al. Fluid overload and fluid removal in pediatric patients on extracorporeal membrane oxygenation requiring continuous renal replacement therapy: a multicenter retrospective cohort study. Pediatr Nephrol. 2020; 35(5):871–882. doi: https://doi.org/10.1007/s00467‐019‐04468‐4. Epub 2020 Jan 17. PMID: 31953749; PMCID: PMC7517652.Dado DN, Ainsworth CR, Thomas SB, et al. Outcomes among patients treated with renal replacement therapy during extracorporeal membrane oxygenation: a single‐center retrospective study. Blood Purif. 2020; 49(3):341–347. doi: https://doi.org/10.1159/000504287. Epub 2019 Dec 19. PMID: 31865351; PMCID: PMC7212702.

      10 A 40‐year‐old man is placed on venovenous (VV) ECMO via a 25 Fr right femoral vein drainage cannula and a 17 Fr right internal jugular vein reinfusion cannula for refractory ARDS secondary to aspiration pneumonitis. He is 6’ 2” tall and weighs 240 lbs (BMI 30.8 kg/m2, BSA 2.35 m2). His initial circuit flow is 5.0 L/min at an RPM of 4000 and drainage pressure of −120 cm H2O; the ECMO specialist is unable to flow > 5.0 L/min because of excessively high drainage pressures (chatter) in the line. Over the next 48 hours, his SpO2 remains at 70% on maximal ventilator settings with a hemoglobin of 14 g/dL; no signs of untreated sepsis, infection, or shock; normal biventricular function on echocardiogram, and a persistently elevated lactate. His circuit flows remain the same and the oxygenator health is excellent. What is the next most appropriate step?Consider adding an additional arterial reinfusion limb to provide increased ECMO support.Consider adding a 21Fr venous reinfusion limb to provide increased ECMO support.Transfuse the patient to a supranormal hemoglobin to improve oxygen delivery.Begin aggressive intravenous fluid resuscitation to improve circuit venous drainage.Consider adding an additional drainage cannula to increase overall ECMO flows. Inadequate ECMO flows is a common problem, and because of fluid dynamics, venous drainage (access) insufficiency is typically the limiting factor rather than reinfusion cannula size. Venous drainage pressures more negative than −100 mm Hg are typically associated with “chatter” in the lines and, therefore, flow limitations. Conversely, flow is often not limited by reinfusion pressures until the reinfusion line pressure is > 300–400 mm Hg. In patients with drainage insufficiency, the addition of a venous or arterial reinfusion limb will not increase ECMO flows and will not provide any additional benefit.Some ECMO physicians advocate for transfusions to normal hemoglobin levels, instead of using typical ICU transfusion practices with a transfusion threshold of 7 or 8 g/dL. However, supplementing the patient’s already normal hemoglobin (14 g/dL) is unlikely to add additional benefit. Additionally, patients with severe ARDS typically benefit from volume removal rather than volume expansion. While fluid boluses may temporarily improve flows by improving venous drainage, this is not an effective long‐term solution.In patients with a large body size, they may require higher than typical ECMO flows, and addition of an extra drainage cannula via the contralateral femoral vein may improve total circuit flow capacity, which will mitigate the hypoxemia and resultant tissue hypoxia.Answer: EDado DN, Ainsworth CR, Thomas SB, et al. Outcomes among patients treated with renal replacement