An Introduction to VV ECMO Andy Pybus Saint

An Introduction to VV ECMO. Andy Pybus Saint George Private Hospital

Conflict of Interest: Andy Pybus MSE (Australia) PL www. ecmosimulation. com

Simulator available at: www. ecmosimulation. com/downloads/ECMOSim 260. zip

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Simulator Components: • • • Documentation Window Monitor Window Therapy Window Device Window (Supervisor Window)

1 2 3 4 5

Minimum Configuration = ‘Stick PC’ + Mobile Phone

Your Resources:

Models: • Physiological – Cardiac, Respiratory, Neurological etc… • Pharmacodynamic – Relaxants, sedatives, Anticoagulants etc… • Mechanical – Ventilator, ECMO system, Defibrillator etc… • Update at between 0. 4 and 100 Hz • Autonomous

Models: • Lung Model – Riley – West • ECG Model – VF synthesis – Conduction pathway – ST Segment synthesis • Arterial tree Model – Aortic Valve • PK PD Models – Effect of ECMO

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

VV ECMO Paradigm: Aims: • To ‘arterialise’ as great a proportion of the venous return as is possible. • To ‘rest’ the native lung.

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Fitness for VV ECMO: Consider: • Reversibility of respiratory disease. • Presence / absence of cardiac disease. • Presence / absence of other disease. – Sepsis. – Bleeding diathesis. • Technical aspects: – Cannulation difficulties. – (Size). • Age.

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

System / circuit design: If it’s urgent: • Less is more!

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Cannula Selection Considerations: • Match cannulae to expected flow rate. • Drainage Cannula >> Return Cannula – ‘Under’ pressure more damaging than ‘Over’ pressure • Consider the use of ‘special’ cannulae. – Armoured Drainage Cannula – ‘Smart’ Cannula 1 – ‘Avalon’ Cannula 2 1. www. smartcanula. com 2. www. avonlabs. com

Cannula insertion: • Percutaneous technique. • Expert assistance. • Imaging guidance. – Ultrasound • TOE • Intra cardiac – Radiological

VV ECMO: Drainage cannula: Aims: – Complete SVC / IVC drainage – Return as close to TV as possible Achieved using: • Single cannula. • Dual cannula. • Composite cannula.

VV ECMO: Drainage cannula: • Single cannula. • Dual cannula. • Composite cannula.

VV ECMO: Single drainage cannula: • Return Cannula – Close to the tricuspid valve. • Drainage Cannulae – As central as possible. – Not too close to the return cannula. – The ‘Goldilocks’ zone.

VV ECMO: Drainage cannula: • Single cannula. • Dual cannula. • Composite cannula.

VV ECMO: Dual-drainage Cannulae: SVC drainage Atrial return IVC drainage

VV ECMO: Drainage cannula: • Single cannula. • Dual cannula. • Composite cannula.

VV ECMO: Composite Cannula: • Cannula Size. • Cannula Configuration. – Dual Drainage Cannulae. – Composite Cannula. • Cannula Position. • Venous Pressure.

Active Venous Drainage: • • Air entrainment potential Threshold resistor effect Haemolysis Platelet activation

Drainage (Venous ) Cannula: Extracorporeal membrane oxygenation using a centrifugal pump and a servo regulator to prevent negative inlet pressure. Pedersen TH, Videm V, Svennevig JL et al. Ann Thorac Surg. 1997 May; 63(5): 1333 -9.

Return (Arterial) Cannula: Blood Flow: 5. 0 lpm Basis for recommendation: ?

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Anti-coagulation management: • • Heparin ACT or APTT? Heparin alternatives The bleeding patient https: //www. elso. org/portals/0/files/elsoanticoagulationguideline 8 -2014 -table-contents. pdf

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Initiating VV ECMO: • ECMO System settings • Ventilation • Sedation

Basic VV ECMO manoeuvres: We can change: • Gas flow. • Blood flow. • Temperature.

VV ECMO: Basic Manipulations: Gas Flow Blood Flow Temperature (VO 2) Summary: • Adjusting Gas Flow will affect the Pa. CO 2. • Adjusting Blood Flow will affect the Pa. O 2. • Adjusting Temperature will affect the Sv. O 2.

VV ECMO: The Effect Of Gas Flow: Gas Flow Blood Flow • Gas flow is analogous to minute ventilation • Pa. CO 2 is to 1/gas flow • Pa. CO 2 is easily controlled – CO 2 ‘Dissociation’ curve Temperature (VO 2)

Why is VV ECMO good for CO 2 clearance? • Linearity of CO 2 dissociation curve. • Oxygenator efficiency at high V: Q ratios. Measuring the efficiency of an artificial lung: 1. Carbon dioxide transfer. Pybus DA, Lyon M, Hamilton J, Henderson M. Anaesth Intensive Care. 1991 Aug; 19(3): 421 -5.

VV ECMO: The Effect Of Blood Flow: Gas Flow Blood Flow Temperature (VO 2) • Pa. O 2 α to blood flow • Blood flow as a fraction of cardiac output • Limits of achievable Pa. O 2 – Effect of cardiac output – Effect of Hb dissociation curve

Pa. O 2 and Blood Flow:

Why is VV ECMO less good for O 2 clearance? • Non-linearity of O 2 dissociation curve. • Oxygenator inefficiency at high blood flow rates.

∆FGF and ∆Q vs Pa. O 2

VV ECMO: The Effect Of Temperature: Gas Flow Blood Flow As Temperature falls: • VO 2↓ ↓ • Sv. O 2 ↑↑ • Pa. O 2 ↑↑ • Oxygenator Efficiency ↑↑ But: Sv. O 2 is also importantly affected by Hct and CO. Temperature (VO 2)

ECMO and Temperature: Blood Flow: 5. 0 lpm

VV ECMO: Basic Manipulations: Gas Flow Blood Flow Temperature (VO 2) Summary: • Adjusting Gas Flow will affect the Pa. CO 2. • Adjusting Blood Flow will affect the Pa. O 2. • Adjusting Temperature will affect the Sv. O 2.

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Ventilator Management: Parameter Before After ECMO Blood Flow (lpm) 5. 0 ECMO Gas Flow (lpm) 2. 5 5. 0 Ventilator Tidal Volume (mls) 500 200 Ventilator Frequency (bpm) 15 4 Ventilator PEEP (cm H 2 O) 10 10 Ventilator Fi. O 2 1. 0 0. 6 RESTING THE LUNG Pa. O 2 Pa. CO 2

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Problem solving during VV ECMO: General Approach: • Time is of the essence • ‘Silent Cockpit’ • Teamwork • Systematic approach – E-Checklists – E-Flowcharts – E-Xpert systems

Problem solving during VV ECMO: Every problem – ask yourself… Is it the system (equipment)? Is it the patient?

Problem solving during ECMO: • • • Oxygen transfer. Carbon dioxide clearance. Flow limitation. VV ECMO-specific problems. (Sedation) (Systemic Inflammatory Response)

Oxygen Transfer

• VO 2 (Max) – Steady State: Quadrox ‘D’ Alberto Contador ~275 ml/min >5500 ml/min

Problem solving during ECMO: • • • Oxygen transfer. Carbon dioxide clearance. Flow limitation. VV ECMO-specific problems. (Sedation) (Systemic Inflammatory Response)

Active Venous Drainage: • • Air entrainment potential Threshold resistor effect Haemolysis Platelet activation

Site of obstruction: • Inflow. • Lung. • Outflow.

The Cannula as a Threshold Resistor : Open Collapsed • Diagnosis: – Chatter – Reduced flow – ↑ Suction pressure • Management: – Reduce rpm – Raise CVP – Reposition cannula – Institute dual drainage

Problem solving during ECMO: • • • Oxygen transfer. Carbon dioxide clearance. Flow limitation. VV ECMO-specific problems. (Sedation) (Systemic Inflammatory Response)

VV ECMO: Recirculation:

VV ECMO: Recirculation: Quantification of recirculation by thermodilution during venous extracorporeal membrane oxygenation. Sreenan C, Osiovich H, Cheung PY, Lemke RP. J Pediatr Surg. 2000 Oct; 35(10): 1411 -4.

Haematocrit and Pa. O 2:

VV ECMO: The Effect of ↑ Cardiac Output: Competing influences: • Pa. O 2 tends to rise because: – As CO ↑, so Sv. O 2 ↑. – As Sv. O 2 ↑↑, so Sa. O 2 ↑↑.

VV ECMO: The Effect of ↑ Cardiac Output: Competing Influences: • Pa. O 2 tends to fall because: – As CO ↑, so fraction of CO passing through the oxygenator ↓. – As CO ↑, so Qs/Qt ↑. ↑ Lynch JP, Mhyre JG, Dantzker DR. Influence of cardiac output on intrapulmonary shunt. J Appl Physiol. 1979 Feb; 46(2): 315 -21.

VV ECMO: The Effect of ↑ Cardiac Output: Net Effect: As CO ↑, so Pa. O 2 ↓.

Workshop Program: • • • Simulator components. The VV ECMO Paradigm. Patient selection. System / circuit design. Cannula selection and insertion. Anti-coagulation management. Basic VV ECMO manoeuvres. Ventilator management during VV ECMO. Basic problem solving during VV ECMO. Weaning from VV ECMO.

Weaning from VV ECMO Fitness for weaning: • Mechanical properties of the lung. • Gas-transfer capabilities. • Radiological appearance.

SUPPLEMENTARY SLIDES HERE.

Desaturation during catastrophic failure:

Why not cool the patient? • • 1. 2. 3. 4. 5. Infection / Immunosuppression 1. Arrhythmias 2. (Coagulation impairment 3, 4). (Drug metabolism 5). Perioperative normothermia to reduce the incidence of surgical-wound infection and the duration of hospitalization. Kurz A et al. N Engl J Med 334: 1209 -1215, 1996 Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. Frank SM et al. JAMA. 1997 Apr 9; 277(14): 1127 -34. Reversible inhibition of human platelet activation by hypothermia in vivo and in vitro. Michelson AD et al. Thromb Haemost. 1994 May; 71(5): 633 -40. Effect of hypothermia on the coagulation cascade. Rohrer MJ et al. Crit Care Med. 1992 Oct; 20(10): 1402 -5. Impact of hypothermia on the response to neuromuscular blocking drugs. Heier T et al. Anesthesiology. 2006 May; 104(5): 1070 -80

Cannulation: • • Cannula selection Insertion Positioning Kinking • Inflow • Outflow • Rotation (Avalon Cannula)