SBCCM Tutorial Practical aspect of Extracorporeal Membrane Oxygenation

SBCCM Tutorial Practical aspect of Extracorporeal Membrane Oxygenation Yan Wing Wa Pamela Youde Nethersole Eastern Hospital 19 April 2011 1

OUTLINE 2

Types of ECMO V-V ECMO V-A ECMO Bad lung good Heart Good lung Bad heart Bad lung Bad heart V-V X X V-A peripheral X (not required) V-A Central 3

Principles of ECMO n Temporary support the failed lung n n n Buy time for the lung to recover n n n Not suitable for irreversible lung failure Less suitable for the lung condition required long time to heal (complication risk > benefit) Keep patient alive Create an optimal condition for the lung to heal Avoid complications related to ECMO 4

Complications of ECMO n n n n n Vessel damage during insertion Unidentified heart failure Bleeding Circuit thrombosis Oxygenator failure Haemolysis Air embolism Circuit rupture Infection Access recirculation 5

Vessel damage n n Appropriate size Too large n n More damage to vessel Increase insertion failure More chance of chattering (cf. size of IVC) Too small n n n Not enough flowe Haemolysis May need to insert one more access cannula 6

Cannulae Arterial cannulae Venous cannulae Supply of cannulae: not reliable! 7

Vessel damage n Arterial damage n n Better having ultrasound guidance n n Need surgical repair Especially in obese patients ? contraindication Need expertise 8

Risk of unidentified heart failure n Desaturation n Esp. with line chattering or Iatrogenic hypotension n n No longer a sign of heart failure even with severe pulmonary oedema CXR - can’t differentiate LVF with underlying lung problem Need repeated fluid challenge Monitor n n n Clinical examination Input >> Output Daily I & O Echocardiography 9

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Risk of haemorrhage n Systemic anticoagulation n n Major cause of mortality of the past ECMO series n n n Regional citrate anticoagulation is not possible 43% of deaths in ANZ ECMO series were related to ICH, JAMA 2009; 302: 1888 -95 Zapol study JAMA 1979; 242: 2193 -6 Gattinoni study JAMA 1986; 256: 881 -6 ICH, GIB, pulmonary haemorrhage or cannulation sites Too low anticoagulation n n Risk of thrombosis Keep flowe >1. 5 L/min Chinese less thrombosis, more haemorrhage Target 50 -60 s APTT (more accurate than ACT for low level anticoagulation) 11

Circuit thrombosis n n n Oxygenator failure Monitor clot formation on oxygenator surfaces Colour of return blood, should be 100% saturated 12

Risk of haemolysis n Minimize n n Larger cannulae size Lower flowe n n n Lowest possible to maintain adequate oxygenation Still >1. 5 L/min to prevent circuit thrombosis May need to insert one more access cannula; high-flow ECMO Change oxygenator if lots of clots exist Monitor n n n Dec. Hb Inc. plasma free Hb Inc. bilirubin Urine colour Renal function test 13

Haemoglobinuria 14

Risk of air embolism n n Life threatening Disconnection before the centrifugal pump n n n Negative pressure Virgin area No connection over these sites Plastic binders to reinforce tightness After pump n n n Positive pressure Bleeding Connection to CRRT circuit 15

Risk of bleeding from circuit rupture n Much less with centrifugal pump n n n Compared with roller pump Important advancement in ECMO design If it really happens, what would you do? n Clamp the line with two line clamps ? n n not practical Basic PPE and then grab the line 16

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Centrifugal Pump n n n Jostra Rota. Flow impeller pump 32 ml priming volume The Rota. Flow had no stagnant blood zones, no shaft and no seals 18

Infection n Risk increases with increasing handling n n n Connection disconnection (CRRT circuit) Blood taking Not adopting aseptic technique 19

Risk of Access recirculation n During insertion n Estimate the depth of insertion before cannulation No need to adjust according to X-ray position, but the degree of access recirculation Oxygen saturation of drained blood n n Rotaflow: colour of blood in access cannula + Sv. O 2 Cardiohelp: colour of blood in access cannula 20

Risk of Access recirculation (2) n Ways to reduce AR n n Separation of the access and return cannulae Return cannula to RV Insertion of one more access cannula, highflow ECMO Avalon bi-caval cannula 21

Risk of further lung damage n Aims n n Decrease tidal volume Decrease Fi. O 2 to an acceptable level (0. 3 -0. 5) n n Beware of reverse diffusion; Fe. O 2 > Fi. O 2 PEEP to keep alveoli open, 10 -15 cm. H 2 O Need to be decreased if pneumothorax; BPF If not able to do this n ECMO is futile n (UCH 1 st case) … On commencement of VV-ECMO, the patient had no other vital organ failure and her oxygenation improved initially. Nonetheless, we failed to wean down the ventilatory support to reduce the risk of VILI…. Hong Kong Med J 2009; 15: 381 -4 22

Decreasing/inadequate Sp. O 2/Sa. O 2 n Increase flowe n n n (inc. cannulae size) More access recirculation More chattering More haemolysis Need more fluid n n Make lung condition worse One more access cannula n n Risk of line complication If insertion failure, difficult to control bleeding 23

Decreasing/inadequate Sp. O 2/Sa. O 2 (2) n Decrease O 2 consumption n If shivering, increase temperaturee n n May help in viral clearance Increase Hct to 0. 4 or Hb to >10 g/dl 24

Venous O 2 saturation Mixed blood O 2 saturation ECMO flow as % of total blood flow 25

Venous O 2 saturation Mixed blood O 2 saturation ECMO flow as % of total blood flow 26

ECMO flow requirement for oxygenation 60% + 100% via ECMO > 90% 27

Increasing Pa. CO 2/Pet. CO 2 n Easy to be removed by ECMO n n cf. Novalung® i. LA membrane ventilator Increase gas flow n n Keep V/Q 1: 1 Avoid lung tissue alkalosis n Decrease ventilator minute volume 28

Carbon dioxide Removal 29

ECMO flow requirement for CO 2 removal Venous CO 2 + ECMO CO 2 Normal CO 2 30

ECMO flow requirement for oxygenation 60% + 100% via ECMO > 90% 31

Novalung® i. LA Membrane Ventilator 32

Renal circuit n Post pump n n Before and after oxygenator CRRT n Positive pressure allowed in CRRT n n Prismaflex Gambro AK 200 S Ultra 33

ECMO and CRRT 34

Types of ECMO V-V ECMO V-A ECMO Bad lung good Heart Good lung Bad heart Bad lung Bad heart V-V X X V-A peripheral X (not required) V-A Central 35

Monitoring – Extracorporeal circuit n n n Pump speed, blood flow & pump noise Circuit: blood clots, air bubbles, kinking, recirculation Lines: silent or kicking Check cannula placement & stability Gas flow & Fi. O 2 36

Monitoring – Patient n Oxygen delivery n Sa. O 2, Hb, Haemodynamics Monitor APTT & platelet count n Observe for bleeding n Assess CNS status n Monitor plasma free Hb n Chest X rays changes n 37

Weaning n Gas flowe n n Flowe n n Most useful Can’t be zero Gas Fi. O 2 n Least useful (when you are using a highly efficient oxygenator) 38

Oxygen content 39

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Questions/Comments? 43