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Extracoperal membrane exchange
- 1. Extracorporeal Membrane Oxygenation Dr. Tenzin Yoezer KGUMSB
- 2. Disclamer: Photos and figures from internet
- 3. Acronyms MCS (Mechanical Circulatory Support) ECLS (ExtraCorporeal Life Support)
- 4. Contents What is ECMO ? Evolution of ECMO Circuit and Types Physiology Indications Veno-venous V/S veno- Arterial ECMO. Cannulation and Circuit
- 5. is an extracorporeal technique of providing prolonged cardiac and respiratory support to persons whose heart and lungs are unable to provide an adequate amount of gas exchange or perfusion to sustain life. The technology of ECMO - derived from CPB Provide cardiopulmonary support in severe heart or lung failure unresponsive to optimal conventional care What is ECMO?
- 6. CPB vs ECMO Major differences CPB ECMO Duration Mins to hours Days to weeks Open reservior Yes No ACT (secs) >400 180 Hemodilution Yes Yes: lesser degree than CPB Patient Asleep Asleep/awake Inflammmaion More less
- 11. Dr Robert Bartlett –Father of ECMO 1975-: Successfully applied bed side ECLS device to treat newborn with meconium aspiration. Evolution of ECMO
- 13. ESPERANZA-at 21 years First Neonatal ECMO survivor..
- 17. Pumps
- 18. Roller Pump
- 19. Centrifugal pump
- 20. Centrifugal pump
- 21. Oxygenator
- 32. Oxygen delivery in ECMO
- 33. VV ECMO circuit
- 34. Oxygen delivery in VV ECMO
- 35. Increasing Oxygen delivery in VV ECMO
- 36. VA ECMO Circuit
- 37. Oxyegen delivery in in VA ECMO
- 38. CO2 physiology on ECMO
- 39. CO2 physiology
- 40. Co2 clearance by ECMO
- 41. Cardiac output on VA ECMO
- 42. Cardiac output on VA ECMO
- 43. Cardiac output on VA ECMO
- 45. Initiaiton Once it has been decided that ECMO will be initiated, the patient is anticoagulated (usually with intravenous heparin) and then the cannula are inserted.
- 46. Cannulation
- 49. - Pump flow rate (cardiac output) calculation Cannulation Patients Pump flows Neonates 150 ml/min x BW Peadiatric upto 10 kg 100-150 ml/min x BW Pead >10 kg 2400 ml/m2/min x BSA Adults 2400 ml/m2/min x BSA Annals of CardiacAnaesthesia,Vol.15:1, Jan-Mar 2012
- 50. Drainage cannula – As central as possible – Not too close to the return cannula Return cannula – Close to the tricuspid valve – But not too close to the drainage cannula
- 51. • Anticoagulant • Heparin IV bolus 50-100 u/kgordirectthrombin inhibitor • Continuous infusion of heparin during ECMO • Measuring heparin effect:activated clotting time (ACT) q 1-2 h • Keep ACT 180-220sec • PPT = 1.5 times normal Before Cannulation
- 52. Modes of ECMO
- 53. Modes of ECMO ECMO can be categorized according to the circuit used
- 54. VV ECMO
- 56. Cannulation in jugular vein not possible. Higher risk for femoral vein/caval thrombosis(?)
- 57. Advantag es Pulmonary circulation/oxygenatio n is maintained. No carotid ligation. Pulsatile waveform maintained. Efficient CO2 removal. Disadvantag es No control of BP. Inefficiency (recirculation). Hypoxemia (low PO2). VV ECMO
- 58. VA ECMO
- 59. Advantages and Disadvantages Advantages Disadvantages Both cardiac and pulmonary support. Instant haemodynamic support Cannulation of major artery and sacrifice of one carotid in newborn No mixing of arterial/venous blood. Poor coronary and pulmonary perfusion Good oxygenation at low ECMO flows Systemic thromboembolism No recirculation. Nonpulsatile flow Oxygenated blood returns to patients arterial circulation Increased incidence of neurological events
- 60. Cannula sites for VA ECMO Venous – IVC or RA Arterial cannula: Right femoral- eassy access ( ipsilateral LL schaemia, thrombosis) Right common carotid artery – risk of large watershed cerebral infarction Right subclavian artery – offers advantage of allowing to ambulate
- 61. Types of ECMO VA ECMO VV ECMO Cannulation site Vein/artery Vein /Vein Hemodynamic support Partial to complete None LV efects ↓Preload ↑Afterload None Coronary oxygenation Native ejection Increased Flow characteristics Non-pulsatile pulsatile
- 62. Priming the circuit • Under sterile condition • Isotonic solution including 4-5 meq/Lof potassium • The prime is circulated through the reservoir baguntil allbubbles are removed • Not recommend to use aprimed circuit after 30 days • For infants,PRC &anticoagulant are added to the prime
- 63. How to initiate ECMO • Pump flow rate:according to round per minute (RPM); normal2000- 5000 RPM VV-ECMO:60%CO VA-ECMO: 100%CO andkeep adequatetissueperfusion • Sweep gas flow sweep gasflow:ECMO flow = 1:1 • Mechanical ventilator setting • VV-ECMO: ultraprotective lung strategies • VA-ECMO: according to patient’scondition • Daily monitoring in allbody systems
- 64. Maintenance — Once the initial respiratory and hemodynamic goals have been achieved, the blood flow is maintained at that rate. Frequent assessment and adjustments - continuous venous oximetry When the venous oxyhemoglobin saturation is below target, increasing one or more of the following: blood flow, intravascular volume, or hemoglobin concentration. Decreasing the systemic oxygen uptake by reducing the temperature may also be helpful.
- 65. Hb > 12 g/dL – to maintain oxygenation (ECMO is only source of oxygen) Ventilator settings : reduced during ECMO - to avoid barotrauma, volutrauma (ie, ventilator-induced lung injury), and oxygen toxicity. Plateau airway pressures < 20 cm H2O and FiO2 <0.5. Reduction of ventilator support is usually accompanied by increased venous return, which improves cardiac output. Early tracheostomy - reduces dead space and improve patient comfort. Patients typically require light sedation during ECMO, but can maintain awake
- 66. Weaning from ECMO Genral guide: Respiratory – improvement on radiographic appearance, pulmonary compliance, arterial oxyHb saturaion Cardiac failure: enhanced artic pulsatilty correlates wth improved LV output Before weaning – Trials: VV ECMO trial– elminates all countercurrent sweep gas through the oxygenator Extracorporeal blood flow remains constant but no gas transfer Pt observed for several hr – during that period ventilator setting are determined to maintain oxygenation
- 68. Weaning from ECMO VA ECMO trial: Temporary clamping of both drainage and infusion lines while allowing ECMO circuit to circuit through a bridge between arterial and venous limb Prevents thrombosis of stagnant blood within circuit Heparin – with saline flush High risk of thrombus formation Once decision is made to discontinue – cannulae remove ECMO VA cannula site – 30 mins compression od arterial site
- 72. Contraindications to VV ECMO Injurious mechanical ventilation for 7 days or longer Major pharmacologic immunosuppression Intracranial hemorrhage that is recent and expanding Increased age BMI > 40 -45 Refusal to accept blood products Miller 9th edition
- 73. Clinical evidence for VV ECMO
- 80. Contraindications to VA ECMO Absolute Acute intracranial hemorrhage/massive stroke Active bleeding Severe aortic insufficiency Relative Contraindication for anticoagulation Advanced age Obesity Active cancer Suicide attempt Chronic hemodialysis End-stage liverdisease Aortic dissection Lack of social support
- 81. ARDS Pneumonia Status asthmatics Chemical pneumonitis Inhalational pneumonitis Near drowning Bronchiolitis Persistent air leak sydrome RSV infection post CHD surgery. Indications of ECMO for Respiratory failure- In Pediatric
- 82. Clinical evidence for VA ECMO
- 86. Likelyhood of survival prior to ECMO RESP score – respiratory failure SAVE SCORE – cardiac failure
- 87. ECMO-related compliations • Bleeding (most common) Systemic anticoagulation Thrombocytopenia • Complications related to vascular access procedures Venous perforation Aortic dissection Pneumothorax • Infection and sepsis • Air embolism
- 88. ECMO-related compliations • Complications relatedto anesthetizedandlaysupinefor days Posterior lung compression and atelectasis Pressure sore • Alterationof pharmacokinetics Antibiotics Sedative drugs • Hemolysis • Distal limbischemiainVA-ECMO • Neurological injury • HIT
- 91. CPR during ECMO
- 92. Summary -ECMO is a bridge ECMO Bridge to recovery Bridge to transplant Bridge to specific treatment Bridge to decision
Notas do Editor
- The technology of ECMO is largely derived from cardiopulmonary bypass, provide cardiopulmonary support in severe heart or lung failure unresponsive to optimal conventional care
- Advances of ECMO machines occurred in early 1950s.
- The heart-lung machien was introduced by Dr John Gibbon in 1953. It is used for large ASD repair to 18 year adult.
- The first clinical application of ECMO life support to non-operation setting was in 1971 for 24 year trauma patient The pt was kept in oxygen member for 72 hours and survied.
- Advanced by Dr
- Age 45 - 2020
- The deoxygenated blood is drained via large veins under negative pressure generated by a pump. It passes throuh the oxygenator which itself is connected to a gas supply After becoming oxygenated it is returned to the patient via vein or artery The heating and the cooling unit regulated the temperature of te circulating blood The sites of vascular access depends on type of ECMO
- The function pumps in ECMO is to generated the force of blood that is drained from the patient and drive it to the oxygenator cirulating blood There are 2 main types of pumps..
- Roller pump works by displacing the blood through a compressible tubing. This pump is preload dependednt – meaning it requires forward blood flow at the inlet to drive the blood or drainage of the blood by gravity. If the pump inflow is limited at the inlet, the negative pressure will be generated in the tubing which wll lead to the formation of miscrospic air bubble which is known as blood cavitation. Roller pump is afterload independent. Pump flow is continued despited elevated pressure at the outlet which can lead to circuit rupture. Roller pump functions by positive displace by foot plate tubing in the fluid. The output of roller pump is determined by RPM and the volume displaced at each minutewhich is dependent on diameter tubing
- Centrifugal pump works by generating a pressure differential btn center and peripheral pump They are non-occlusive by design. Thus is necessary to clamp the central lines to prevent backflow from the patient
- Centrifugal pump are both preload and afterload dependent This function as sensitive to volume available to the pump inlet and the resistance at the outlet As result of varying sensitive to both preload and afterload the pump flow cannot be predicted from pump speed(RPM) and flow meter is required to measure the actual blood flow through the circuit.
- Oxygenator is the site of gas exchange. It has basic structure of hollow fiber membrane. The hollow fibers are anatomical equivalent to the alveoli of the lung. Gas flow inside the fiber and blood flow outside the fibers Gas exchange occurs by diffusion as in human lungs Newer membrane exchangers are made from PMP( has lower oxygenator failure from plasma leakage) and it has several advantages over Polypropylene
- The total O2 content in the arterial blood is the sum of O2 bound to Hb and dissolve the blood Majority are in bound form and very small in dissolve form Thus the main determinant of the arterial O2 content are Hb conc and % of Hb is saturation with O2 Therefore formula can be simplified as…. 1.34 is the amount of O2 bound to 1g Hb and
- in normal resting stage, the arterial o2 content is roughly 20 ml?dL
- in normal resting stage, the arterial o2 content is roughly 20 ml?dL With normal CO of ….
- in normal resting stage, the arterial o2 content is roughly 20 ml?dL With normal CO of …. The total O2 delivery is roughly….
- Oxygen delivery is ~ to Hb conc. Here 3 curves showing O2 delivery at 3 different Hb level of 15, 10, 7.5 assuming O2 is 100%. N – denotes normal O2 delivery in normal pt with normal Cardiac index and Hb
- If have to remember adeqaute tissue oxygenation cannot be reflected by simply measuring the partial pressure of O2 or Oxygen saturation in the blood O2 adeqacy is achieved by balanced between rate of O2 delivery (DO2) and rate of O2 consumption(VO2) Oxygen delivery is dependednt on arterial O2 content and CO O2 consumption is dependt on metabolic rate O2 need and consumption is calculated by difference btn artrial O2 content and venous O2 content
- Gas exchange in the membrane oxygenator is very similar to the native human lungs O2 diffuses across the membrane to saturate the venous blood and CO2 is removed in the reciprocal direction MV is the biological analogs of as flow to the membrane O2 oxygenator ECMO BF is analog to pulmonary BF
- O2 delivery on ECMO circuit from the membrane and o2 from native pulmonary circulation is the total o2 delivery
- In VV ECMO circuit- ECMO and native circulates(functions) in series Fully oxygenated blood circulated by ECMO enters in the RA and mixes with the deoxygenated blood returing from the systemic circualtion Blood then distributes to the pulmonary circulation where depending on the native lungs further oxygenates the blood This blood is then circulated to the systemic circulation by LV
- Thus in VV ECMO O2 delivered from the ECMO system is the function of Hb level, the diffeence of O2 content at blood enteing and exiting the membrane lung and the ECMO BF
- Thus in VV ECMO to increase O2 delivery are Transfusing – to increase Hb Adding extra drainage cannula – to increase the BF to ECMO Adding membrane lung But later 2 methods are cumbersome compared to transfusion other methods are …..
- VA ECMO – ECMO and native circulation functions in parallel Deoxygenated blood from RA is drained into the ECMO circuit or passes through the pulmonary circulation Oxygenated blood is return to the circulation either by anterograge fashion to Left heart or retrograde fashion from ECMO return cannula
- Because lungs often function normally and provide gas exchange in VA ECMO, the effect of mixing ECMO and native venous flow is minimal
- In normal circumtances where repiratory qaotion is 1, CO2 production is ~ o2 consumption Due to more diffusible and solubility of CO2, the BF requirement for CO2 clearance is minimal than O2 delivery Hence, routine oxygenator on ECMO is primarily on oxygenation parameter and CO2 is adeqaute at conventional ECMO settings
- The equivalent MV of membrane lung is sweep gas flow. CO2 clearance is dependednt on membrane geometry, SA, material Sweep gas flow, difference b/n inlet and sweep gas nad minimally by blood flow may casue poor CO2 clearance If water condensate form on gas interface, the gradient for CO2 clearance is lost To prevent this – routine membrane flushing with high sweep flow at regular interval
- CO = HR x SV SV is determined by=… For pts on ECMO preload decreases as result of blood being drained from RA, Less blood flow to RA and LV= decrease pressure
- Concurrently the LV afterload increases as rsult of return of blod from ECMO to aorta in retrograde manner Sympathetic activity is activated as a result of circulatory insufficiency There is Minimal direct affect on native myocardial contratility apart from decrease LV preload resulting in performing on lower frank starling curve
- ECMO canula are the cathers that drain blood from the patient and return back to the pt. Selection of canula depends on variety of factors – pathodlogy, patient habitus, vascular anatomy, experience of the center(previous experience)
- Regardless of the type of ECMO configuration, peripheral or central, VV or VA, traditionally is a single lumen catheter at different site( one for venous, one for arterial) In most circumtances canula used in venous drainage are multi-stage cannula wth side holes at 10-20 cm to enhance the drainage of the venous cannula. Arterial cannula are usually shorter and has side holes only at the tip of the cannula.
- Wire reinforced to resist kinking and withstand high negative and postive pressure generated in the circuit. Recent cannula has dual lumen – allows draiange and return from single vein in VV
- Action of heparin depends on antithrombin (AT3) AT3deficiency or < 50% normal – replace with FFP
- 1. Venoarterial (required for cardiac support, appropriate for respiratory support) 2. Venovenous (no hemodynamic support, preferred for respiratory support because it avoids using a major artery and avoids potential systemic embolism) 3. AV-arteriovenous (limited to low blood flow, specifically for CO2 removal)
- There are 2 main ECMO configuration – VV ECMO, VA ECMO Broadly speaking VV ECMO is used in respiratory failure, VA ECMO for cardiac failure
- VV ECMO is the preferred support for respiratory failure when cardiac function is preserved Deoxygenated blood is drained from the lung via large vein, oxygenated by membrane oxygenator and return to RA where it is then pumped to the systemic circulation by the native cardiac ouput This means VV ECMO primarily carry out gas exchange process when the native lungs are unable to do so.
- usually placed in the right or left common femoral vein (for drainage) and right internal jugular vein (for infusion). The tip of the femoral cannula should be maintained near the junction of the inferior vena cava and right atrium, while the tip of the internal jugular cannula should be maintained near the junction of the superior vena cava and right atrium.
- VA ecmo
- inferior vena cava or right atrium (for drainage) and an arterial cannula is placed into the right femoral artery (for infusion). Other sites:
- Following cannulation, the patient is connected to the ECMO circuit and the blood flow is increased until respiratory and hemodynamic parameters are satisfactory
- Oxygen deliver depends on Hb
- VA ECMO = EF > 20-25%= proceed to weaing Deoxygenation challenge Starts from FiO2 1%.....itirate to room air Pass measn = CO2 challenge ( ECMO challenge – reduce by 30% guided by ABG, maintain PaCO2 < 50 mmHg, RR 30, SPO2 > 88) = if pass
- P0.1 = negative pressure measured 100 ms after the initiation of an inspiratory effort performed against closed circuit Normal -0.5 to 1.5 cmH20 Signifiest central respiratory drive.
- Reduce the flow rate of ECMO by 30% form intitiation, when the flow rate is < o.5 – 1L/min = off ecmo First ecmo, keep ventilator settig ( even if PS is minimal) Decannulate after 12- 24 hours = high chance of relaspse. In Pead decrease flow to 100mL/min
- Murray score( 4 criteria): 1] PaO2/FiO2 gradient for oxygen 2] Degree of PEEP 3] Number of quadrants affected as shown on the chest radiograph 4] lung compliance The final score is calculated by the addition of the component parts. Score 0= no lung injury; 1–2.5 = mild to moderate lung injury >2.5= severe lung injury Berlin criteria = PF ratio < 80% ECMO, < 150 muscle relaxant(severity of ARDS is rated as mild, moderate, or severe based on the PaO2/ FiO2 gradient for oxygen if other criteria are present) In general, patients with severe ARDS (PaO2/FiO2 gradient of < 100 mm Hg with PEEP > 5) are potential candidates for ECMO as the mortality without ECMO is approximately 40
- The Murray lung injury score was develop to stratify the severity of acute lung injury The final score is the average of the score of the 4 components . The PF ratio, the extend of the lung infiltration on the CXR, the level of PEEP and the lung compliance It guides the patient referral to the centers with ECMO capabilities or it guides as initiation for ECMO indication.
- ESLO High pressure ventilation (peak insp pressure >30 cm of H2O) for >7days. High FiO2 requirement (>0.8) for >7days Limited vascular access. Refusal to accept blood products
- The publish studies for VV ECMO are notable for 2 major RCT and some case control studies. This clinical trial primarily has focused on pts with ARDS
- The landmark trial for ECMO use in ARDS is the CESAR trial in 2009 180 pts with respiratroy failure defined by Murray score of > 3 or pH < 7.2 were randomized for consideration for treatment by ECMO or conventional mx by ventilatory support mx
- Patients who were randomized with consideration for treatment by ECMO mx had higher 6 months survival of around 63% compared with 47% in the conventional mx arm
- During the 2009 H1N1 influenza pandemic pts with ARDS who were referred and transferred to ECMO centers in the UK were compared with matched pts who were not refferd to ECMO centers The hospital mortality for pts who are refrred to ECMO mx was lower with RR of 0.45
- The EOLIA(ECMO to rescue Lung Injury in Severe ARDS) trial was published in the New England journal of Medicine May 2018. 249 pts with very severe ARDS meeting of the the these three criteria were randomized to receive immediate VV ECMO or continue convectional ventilatory treatemnt.
- The 60 day mortality for ECMO group was 35% and 46% in non Ecmo which not snificcant with p value of 0.09 However it should be noted that the crossover in 1/3(28%) of the control patient may have diluted the result.
- ECMO CPR – refractory cardiac arrest with no ROSC within 10 mins *** Difficult intubation = CICO
- There is no RCT trial for the use of VA ECMO Current literature are mostly of observational studies
- In the cohort of 71 patients in Taiwan with ST segment elevation MI complicated with cardiogenic shock The 30 day mortality for pts supported with VA ECMO support had significantly lower than pts not on ECMO
- A retrospective study from a French group included patients with fulminant myocarditis between 2003 and 2009 This group reported ICU survival of 68% in ECMO group with refractory circulatory failure
- The largest meta-analysis including almost 1200 patints from 22 studies who received the ECMO for refractory cardigenic shock or cardiac arrest They reported a overall hospital survival rate of 40.2%
- Bleeding – 30 -50%. Prevention = Platelet count > 50,000 and maintaining target ACT
- Thromboebolsim VA-ECMO > VV ECMO = due to infusion is into the systemic circulation
- Findings: Total – 1035 pts