Ecmo

ecmo

1. EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO) PRESENTER: DR.NIKHIL

2. OVERVIEW INTRODUCTION HISTORY PRINCIPLE CIRCUIT & COMPONENTS TYPES INDICATIONS and CONTRAINDICATIONS ECMO MECHANISM COMPLICATIONS

3. INTRODUCTION A form of extracorporeal life support where an external artificial circuit carries venous blood from the patient to a gas exchange device (oxygenator) where blood becomes enriched with oxygen and has carbon dioxide removed. The blood is then returned to the patient via a central vein or an artery.

4. 5 5 History of Extracorporeal Life Support 1950s Development of membrane oxygenator in laboratory 1971 First successful case 1972 First successful paediatric cardiac case 1975 First neonatal case (Esperanza) 1975-89 Trial in ARDS, 10% survival 1990 Standard practice for neonates and paediatrics in some centres 2000 Standard practice for adults in some centres 2009 Publication of the CESAR trial which led to a significant growth in the use of ECMO for ARDS cases

5. ECMO PRINCIPLE Desaturated blood is drained via a venous cannula CO 2 is removed, O 2 added through an “extracorporeal” device The blood is then returned to systemic circulation via another vein (VV ECMO) or artery (VA ECMO).

6. ECMO serves as a BRIDGING THERAPY and not a curative therapy. Used as a -bridge to recovery :– i.e., buying time for patient to recover -bridge to decision :- provide temporary support to patient and allow clinicians to decide on the next step. -bridge to transplant :- provide support to patient while awaiting suitable donor organ.

7. ECMO CIRCUIT & COMPONENTS The basic components of ECMO circuit includes a blood pump membrane oxygenator heat exchanger C ontroller and in line monitors cannulas tubings

8. PUMPS : The pump works both to push blood through the oxygenator and back to the patient and also to augment venous outflow to the circuit. Two types of pumps are used in the ECMO circuit: the centrifugal pump the roller pump

9. CENTRIFUGAL PUMPS : The centrifugal pump consists of: A set of cones A magnetic disc. Vortex effect The flow is variable and is dependent on: the blood volume from the patient size of venous outflow cannulae size of the disc head pump speed.

10. ROLLER PUMPS The roller pump compresses the circuit tubing and pushes the blood through the raceway of the pump. The flow from the roller pump is dependent on: the size of the tubing in the raceway occlusion pressure of the rollers pump speed blood volume.

11. ROLLER PUMPS  Able to set totally or Partially occlusive  Positive displacement – pushes blood by squeezing raceway  Flow = (stroke volume x rpms)  Flow is not dependent on resistance CENTRIFUGAL PUMPS  Non – occlusive  Passive displacement  Cones or impellers create kinetic energy using centrifugal force of fluid constrained vortexing  Rpm’s are proportional to resistance  Flow is inversely proportional to resistance

12. Membrane Oxygenator : ECMO circuits have a gas exchange device called oxygenator, to add Oxygen and remove CO2 from blood. V/Q Mismatch.

13. Two different devices have been developed for gas exchange: the silicone membrane oxygenator the hollow fiber oxygenator (HFO). Silicone membrane oxygenator consists of a thin silicone sheath separated by a plastic screen spacer.

14. Previously, silicon membrane oxygenators were used which are being replaced by Hollow fibre PMP(polymethyl pentene) membrane oxygenators. These are extremely efficient at gas exchange and demonstrate minimal plasma leakage, low resistance to blood flow.

15. Oxygen exchange is dependent on: thickness of the blood film membrane material fraction of inspired oxygen (FIO2) hemoglobin concentration. Carbon dioxide removal depends on The sweep: higher sweep speeds result in higher CO2 removal. The flow: if the flow is increased without increasing the sweep, then CO2 removal can be impeded. The presence of water vapour in the membrane: this can impede CO2 removal.

16. HEAT EXCHANGER : In adults, it is usually built within the oxygenator. In paediatric cases, it is connected separately after the oxygenator in the circuit. It is used for temperature regulation of the extracorporeal blood.

17. BRIDGE The bridge is a connection between the venous (drain) and arterial (return) components of the circuit. Bypass to allow the isolation of the patient from the circuit. This allows the circuit to continue to flow thereby reducing the risk of clot formation when weaning the patient off the circuit.

18. In-Line Monitors Monitors Continuous measurement of flow rate, pH, oxygen saturation, and PCO2 have been built into the ECMO circuit, on both the venous and arterial sides. Activated clotting time (ACT) analyzers are also built into the system to ensure that the proper clotting time is maintained. Unless contraindicated, the circuit is infused with heparin to prevent clot formation. Commonly used parameters range from 180 to 220 seconds or 1.5 times the normal range.

19. Controller panel The controller allows the operator of the ECMO circuit to adjust the settings as needed. The settings that are typically adjusted are: The RPM:  The higher the RPM, the higher the rate of blood flow through the pump. The sweep:  More gas entering the oxygenator allows for better CO2 removal. The controller has a pole-mounted graphic display that allows the adjustment of the pump RPM.

20. CANNULAS Drainage and Return Cannulas: The drainage cannula allows blood to flow through the pump to the oxygenator. The return cannula returns blood from the oxygenator to the patient. The typical adult ECMO circuit handles anywhere between 1-6 litres per minute of blood flow, so large bore cannulas are needed to accommodate this.

21. The key points about the drainage and return cannulas are: They are typically 23-29 French (about 7.5 - 10 mm in diameter) The larger and shorter the cannula, the less resistance to flow it has Drainage cannula are situated in large central veins, typically IVC, SVC, or the right atrium Depending on the configuration, return cannula are situated either in the right atrium, or in the aorta The drainage cannula often have multiple orifices so they drain all along their length.

22. TUBINGS : Depending on the heparin coating, they are of 2 types : - regular - heparin coated

23. TYPES There are 2 separate modes of access for ECMO: Venovenous (V-V) : isolated respiratory failure Veno -arterial (V-A) :isolated cardiac failure or combined cardiopulmonary failure. A dialysis membrane can be added to either circuit to provide simultaneous continuous renal replacement therapy

24. The main principles of V-V ECMO are : Deoxygenated blood is drained from a large central vein, and oxygenated blood is returned to the right atrium or another large central vein. Does not bypass the heart or the lungs. Provides no hemodynamic support, the patient’s native cardiac function must be intact Typically used in hypoxic respiratory failure. The most common reasons are: ARDS refractory to conventional management. Primary Graft Dysfunction after a lung transplant. Hypoxia in the context of severe lung disease as a bridge to lung transplantation.

25. In V-A ECMO: The ECMO circuit is connected in parallel with the heart and lungs: blood going through the ECMO circuit bypasses the heart and lungs. Blood that doesn't go through the ECMO circuit travels through the heart and lungs, and mixes with the ECMO circuit blood in the aorta. The pulsatility of the blood flow to the patient's tissues is markedly reduced. Typically used in low cardiac output states refractory to conventional therapies. The most common reasons for V-A ECMO are: Myocardial ischemia Dilated cardiomyopathy Persistent ventricular tachyarrhythmias Myocarditis End stage pulmonary arterial hypertension

26. As a result of this configuration, two parallel circulations are created: Blood passing through the native heart and lungs that is ejected into the aorta The oxygen content of this blood depends on adequate oxygenation and ventilation by the lungs. Blood passing through the ECMO circuit that is returned into the abdominal aorta Assuming the membrane oxygenator is working properly, this blood will be richly oxygenated.

27. Blood from these two parallel circulations will mix somewhere in the aorta, and their relative contributions to systemic oxygen delivery is a function of how much flow is going through each circulation. Territories most vulnerable to hypoxia are those with blood supply from the proximal aorta. The coronary arteries supplying the myocardium. The innominate artery supplying the right arm and the brain. The left common carotid artery supplying the brain

28. INDICATIONS OF ECMO ELSO GUIDELINES : -Acute severe cardiac failure or respiratory failure with high mortality risk and reversible and non-responsive to optimal conventional therapy. -ECLS is considered at 50% mortality risk and indicated at 80% risk.

29. ELSO GUIDELINES FOR ADULT RESPIRATORY FAILURE INCLUSION CRITERIA : In hypoxic resp iratory failure due to any cause (primary or secondary) 50% mortality risk associated with a PaO2/FiO2 < 150 on FiO2 >90% and Murray score 2-3 80% mortality risk is associated with a PaO2/FiO2 <100 on FiO2 >90% and Murray score 3-4 despite optimal care for 6 hrs or more. CO2 retention on Mechanical Ventilation despite high Pplat (>30cm H2O) Need for intubation in a patient on lung transplant list Immediate cardiac or respiratory collapse (Pulmonary Embolism, blocked airway) unresponsive to optimal care.

30. INDICATIONS : Reversible Respiratory Failure : ARDS Severe Pneumonias Severe Acute Asthma Chemical and Inhalation hypersensitivity Pneumonitis Near Drowning Post traumatic Lung Contusion Bronchiolitis Obliterans Autoimmune lung diease - Vasculitis, Good Pasture Syndrome

31. Irreversible or Chronic Respiratory Failure : It is indicated as a bridge, only when- -patient is for lung assist device. Eg : PAL (paracorporeal artificial Lung) -patient is waiting for lung transplant.

32. CONTRAINDICATIONS : No absolute contraindications to ECLS in respiratory failure. Relative contraindications due to poor outcome are : - Mechanical Ventilation at high settings ( FiO2 >90%, P-plat >30) for 7 days or more. Major pharmacological immunosuppression (absolute neutrophil count < 400/mm3) CNS haemorrhage which is recent or expanding Non recoverable co-morbidity such as major CNS damage or terminal Malignancy Age : no specific age contraindication but increasing risk with age .

33. ELSO GUIDELINES FOR CARDIAC FAILURE : Cardiogenic shock -inadequate tissue perfusion manifested as hypotension and low cardiac output despite adequate intravascular volume. -shock persists despite volume administration, ionotropes and vasoconstrictors and intraaortic balloon counterpulsation if appropriate -Acute myocardial infarction -Myocarditis -Decompensated chronic cardiac failure -Post cardiotomy shock -Peripartum cardiomyopathy Septic shock

34. CONTRAINDICATIONS ABSOLUTE : -Unrecoverable heart & not a candidate for transplant /VAD -Chronic and severe organ dysfunction (Emphysema, cirrhosis, renal failure) -Prolonged CPR without adequate tissue perfusion RELATIVE : -Anticoagulation -Obesity -Advanced age

35. PAEDIATRIC INDICATIONS AND CONTRAINDICATIONS ECLS should be considered in patients with marginal or inadequate gas exchange at risk of ventilator-induced lung injury and who are failing less invasive therapy. Specifically:- severe respiratory failure as evidenced by sustained PaO2/FiO2 ratios <60-80 or OI>40 where OI = {mean airway pressure (cmH2O) x FiO2 (%)} / PaO2 (mmHg) Lack of response to conventional mechanical ventilation ± other forms of rescue therapy ( eg. high frequency oscillatory ventilation (HFOV), inhaled nitric oxide, prone positioning) Elevated ventilator pressures ( eg. mean airway pressure >20-25 on conventional ventilation or >30 on HFOV or evidence of iatrogenic barotrauma)

36. Absolute contraindications - Lethal chromosomal abnormalities ( eg. Trisomy 13 or 18) - Severe neurological compromise ( eg. intracranial hemorrhage with mass effect) - Allogeneic bone marrow transplant recipients with pulmonary infiltrates - Incurable malignancy Relative contraindications - Duration of pre-ECLS mechanical ventilation >14 days (4,7) - Recent neurosurgical procedures or intracranial hemorrhage (within the last 1-7 days,depending on neurosurgical advice) - Pre-existing chronic illness with poor long-term prognosis and MODS High risk patients - Infants with pertussis pneumonia or disseminated herpes simplex - Cytomegalovirus infection and severe coagulopathy or thrombocytopenia

37. Starting ECMO Vascular Imaging Location Equipment Patient preparation: The patient should have central venous access prior to cannulation. The patient should have invasive hemodynamic monitoring prior to cannulation. Anesthesia Anticoagulation: The patient must be systemically anticoagulated with heparin, typically a 5000 unit bolus.

38. ECMO CANNULATION The cannulation process for V-V ECMO and peripheral V-A ECMO is carried out using the Seldinger Technique. For central V-A ECMO, the return cannula is placed via a sternotomy and direct placement into the thoracic aorta. When the cannulas are appropriately placed, they are joined to the ECMO circuit tubing by placing the two ends together while pouring saline over them to ensure no air is entrained into the circuit.

39. Cannula Verification: It is important to verify that the cannulas are placed correctly, as this can have a large impact on the hemodynamics. Cannula placement can be verified in the following ways: X-ray Transthoracic echocardiography Transesophageal echocardiography

40. Daily Care of the ECMO Patient: Circuit Settings Flow Flow is not directly controlled by the pump, instead the pump is set to a certain RPM. In general, the higher RPM the higher the flow. A rule of thumb is that the flow in mL/min is about +/- 500 mL higher than the RPM of the pump. For example, if the pump is at 3000 RPM, then the flow through the pump should be anywhere from 2500 to 3500 mL/min. Consider trying to increase the flow if: There are signs of hypoxemia, e.g. decreased SpO2, decreased PaO2. There are signs of decreased perfusion of tissue e.g. elevated lactate, decreased urine output (V-A ECMO only). Consider trying to decrease the flow if: The patient is showing recovery of intrinsic ability to oxygenate.OR recovery of cardiac function (V-A ECMO only). There is significant hemolysis and the pump speed is above 4500 RPM. There is significant chatter and the flow rates are erratic (this may mean your pump speed is too high and it is causing " suckdown " of the return cannula vessel).

41. Sweep The sweep gas rate controls the rate of CO2 removal. The FiO2 of the sweep gas helps control the PaO2. Sweep gas flow rates vary between 0-15 litres per minute. Sweep gas adjustments should be considered in the following scenarios: The patient develops relative hypercarbia : sweep gas should be increased. The patient develops relative hypocarbia : the sweep gas should be decreased. The patient develops hypoxemia : the FiO2 of the sweep gas may be increased. The patient demonstrates increased work of breathing : the sweep gas may be increased (although this may not work to relieve the work of breathing).

42. Blood Pressure: The blood pressure should be measured invasively, traditionally in the right radial artery if the patient is on V-A ECMO. Just like in any ICU patient, the MAP should be maintained at a high enough level to allow for adequate organ perfusion. Vasopressors and inotropes may be used in ECMO patients in similar doses to patients who are not on ECLS. Laboratory Values: The following should be measured daily: CBC ABG Electrolytes Creatinine Lactate

43. Echocardiography Daily Assessment of Bleeding Sedation Anticoagulation

44. Mechanical ventilation Apply the same principles of lung protective ventilation to ECLS patients .The main things to keep in mind are: Limit the FiO2 as hyperoxia can cause reabsorption atelectasis and damage lung tissue. Keep the plateau pressures low to protect the lungs from barotrauma. Use low tidal volumes to protect the lung from volutrauma . Maintain PEEP to avoid atelectrauma and total consolidation of the lung.

45. WEANING & TRIAL OFF OF ECMO INDICATIONS : -For patients with Respiratory failure, improvements in radiographic appearance, pulmonary compliance and arterial oxyHb saturation. -With cardiac failure, enhanced aortic pulsatility correlates with improved left ventricular output. -One or more trials of taking the patient off of ECMO should be performed prior to discontinuing ECMO permanently.

46. VV ECMO trials are performed by eliminating all countercurrent sweep gas through oxygenator. Blood flow remains constant, but gas transfer doesnot occur. Ventilator settings are adjusted. The following steps happen: The sweep gas flow to the oxygenator is reduced to zero. The patient is observed for signs of respiratory distress. The tidal volumes, minute ventilation and respiratory rate are measured on the ventilator. The patient's vital signs are monitored. Serial blood gases are taken to monitor the gas exchange of the native lungs

47. VA ECMO trials The cause of cardiogenic shock should be resolved. A minimum of 24-48 hours on V-A ECMO before trying to wean. MAP > 70 mmHg. Low doses of vasopressors and inotropes. Oxygen saturation > 95%. Central venous saturation > 70%. Resolving pulmonary edema. LVEF >25-30%. Normal right ventricular function. Blood lactate level low and not increasing.

48. Decrease flow in steps to 1 L/min at FiO2 100% or decrease flow to 2L/min then decrease sweep gas FiO2 to maintain SaO2 >95% Need temporary clamping of both drainage and infusion lines, while allowing to circulate through a bridge between the arterial and venous limbs. The patient is continuously monitored for signs of inadequate cardiac output: Rise in filling pressures Elevation of blood lactate Hypoxemia High inotrope and/or vasopressor requirements Decreased central venous saturation Echocardiographic signs of right or left ventricular dysfunction

49. COMPLICATIONS Bleeding Thromboembolism Cannulation related Heparin induced thrombocytopenia VV ECMO specific complications VA ECMO specific complications Neurological complications

50. COMPLICATIONS CIMPLICATION SIGN ACTION Large thrombus formation Dark or white areas on oxygenator/tubing connectors, increase pressure gradient across oxygenator Change oxygenator or circuit, increase heparin infusion Cannulae complication Venous cannulae too close to one another (V-V ECMO No color difference between venous and arterial cannulae X-ray confirmation. Pullback cannula Arterial cannula in ascending aorta Aortic valve insufficiency, left ventricular failure X-ray and echocardiographic confirmation. Pullback cannula Hypovolemia, pneumothorax, pericardial tamponade Chatter’’ (shaking) of cannulae Hypovolemia: Administer Fluids, decrease ECMO flow; pneumothorax: thoracostomy tube; pericardiac tamponade: pericardiocentesis and/or pericardial window

51. CIMPLICATION SIGN ACTION Air embolism Venous Lack of blood flow (airlock) Stop ECMO flow. Change circuit or oxygenator. Arterial Stroke, hypotension Stop ECMO flow. Trendelenburg position Oxygenator failure Increase gas or pressure gradient across the membrane, thrombocytopenia, hemolysis Replace oxygenator Pump failure Decrease blood flow/pump speed Manually hand crank the pump and replace pump or power source Hemorrhagic stroke Little clinical evidence. Brain CT scan needed Prevent hypertension and excessive anticoagulation Lower extremity ischemia (with V-A ECMO) Cool, pale extremity, signs of compartment syndrome (late), rhabdomyolysis (late) Use smaller bore femoral arterial cannula, place shunt from the arterial cannula directed to distal femoral artery

52. BLEEDING : Occurs in 30-40% of patients on ECMO Due to continuous heparin infusion and platelet dysfunction. T reatment : -maintaining platelet count > 1 lakh/mm3, target ACT reduces the risk of bleeding. - surgical exploration if major bleeding occurs. - if bleeding occurs, decrease heparin infusion & maintain ACT at 160 sec. - plasminogen inhibitors can be given but may increase risk of circuit thrombosis.

53. THROMBOEMBOLISM : It is more common with VA ECMO than VV ECMO as infusion is into systemic circulation. A sudden change in pressure gradient indicates thrombus formation.

54. CANNULATION RELATED : Vessel perforation with haemorrhage. Arterial dissection Bleeding Distal ischemia in VA ECMO T reatment : inserting distal perfusion cannula in femoral artery distal to ECMO cannula.

55. VV ECMO SPECIFIC COMPLICATIONS RECIRCULATION : -Here, reinfused blood is withdrawn through the drainage cannula without passing through the systemic circulation. The degree of recirculation determines the efficiency of ECMO in providing oxygenation. I NTERVENTION : Increasing the distance between cannulae Use of single site double lumen cannula Addition of another drainage cannula

56. VA ECMO specific complications Pulmonary haemorrhage Cardiac thrombosis -retrograde blood flow in the ascending aorta in VA ECMO. -stasis of blood can occur if left ventricular output is not maintained leading to thrombosis. Coronary or cerebral hypoxia -coronary usually gets blood from native circulation (from LV) -With compromised LV & LUNGS, relatively hypoxic perfusion occurs.

57. THE HARLEQUIN SYNDROME (north south syndrome) Saturation of upper part of the body is lower than that of lower half. This is due to flow competition in the aorta – recovering heart vs ECMO pump High cardiac output from native recovering heart prevents the retrograde flow of ECMO to perfuse upper part. If pulmonary function is impaired : -”BLUE HEAD” : deoxygenated blood to upper part -”RED LEGS” : hyperoxygenated blood to lower part

58. In case of respiratory failure, flow competition in the aorta between the recovering native heart and the extracorporeal circuit can lead to a “Harlequin” or “North–South” syndrome.

59. TREATMENT : -increase the ECMO flow if no cardiac stunning -higher ventilator setting or consider HFOV (High Frequency Oscillatory Ventilation) -switch to VV ECMO if persistent lung failure.

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