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Oxygenators for extra corporeal life support (ECLS)

The purpose of this guideline is to provide a framework to support the extra corporeal life support (ECLS) team in the management of providing ECLS support.

Note: While this guideline/ICP refers to the ‘child’ throughout, all activities are applicable to young people.

ECLS plasma tight hollow fibre oxygenators are used for ECLS.

Plasma tight hollow fibre, non porous membranes have been developed to meet the needs of a long term oxygenator, without the known problems of plasma leakage from hollow fibre porous membranes used for conventional cardiopulmonary bypass.

Advantages:

  • ease of priming 
  • bioactive coating (reduces the incidence of clot formation) 
  • low resistance across the oxygenator causes less destruction to the red cells

Disadvantages:

  • low transmembrane pressure limits use of haemofiltration over the oxygenator 
  • increased risk of gas passing through the membrane into the blood side if gas pressure exceeds blood flow pressure
  • anaesthetic gas (eg Isoflurane) should not be used with hollow fibre membranes as the transfer across to patient side is minimal  

Characteristics of the Medos oxygenators: polymethylpentane coated, hollow fibre, plasma tight (non porous membrane) (Chalice Medical).

Background

Table showing characteristics of Medos oxygenators
Characteristic Medos Neonatal 800 Medos Paediatric 2400 Medos Hilite 7000
Membrane surface area (m2) 0.31 0.63 1.9
Static priming volume (mls)  56 99 275 
Max. blood flow (ml/min)  800  2300  7000 
Approx rated flow (l/min) (see below) 0-0.8  0-2.4  1-7 
Max. gas flow (l/min)  3.0  6.0  10
Minimum gas flow (ml/min)  100  100  100 
Typical patient weight (kg)  <4  >5<12  >12 

Rated flow = maximal flow of 75% saturated blood which can be fully oxygenated. Potential for CO2 exchange is higher.

QuadroxD Jostra Oxygenator

Polymethylpentane hollow fibre plasma tight ie non-porous membrane.

  • Surface area m2: 1.8
  • Priming volume membrane/heat exchanger (ml): 250
  • Maximum blood flow (ml/min): 500-7000 ml
  • Maximum gas:blood flow ratio 6:1
  • Minimum gas flow (mls): 100
  • Typical patient weight (kgs): <10

 

Identify oxygenator type in use. 

Note maximum blood flow and maximum gas flow, do not exceed these values. 

The minimum gas flow for  both oxygenators is 100mls, check carefully for rising paC02.

Transmembrane pressures (pre in-post out) is low due to the structure of the membrane (>50mmHg). Higher transmembrane pressures for the membrane can be tolerated. This should be reviewed on an individual patient basis and discussed on the ward round. 

Never use alcohol based fluids on membrane ports or surfaces (except on needle-free access devices) 

Due to the hollow fibre (plasma tight) structure of these membranes, condensation can build up on the fibres leading to high carbon dioxide levels and lower oxygenation. To rectify this turn the sweep gas up by 100-500mls (for approximately one minute) keeping below the maximum gas flow for that membrane to physically drive water out of the membrane. Then turn the sweep back to previous levels and check post membrane gas after 15 minutes. Do not leave the sweep gas up high and unattended as there is a potential risk of gas passing into the blood when the sweep gas is increased. If this incident is suspected turn the sweep gas down immediately. Contact ECMO co-ordinator, perfusionist or ECMO fellow if problem persists after three increases in sweep gas flow. Do not leave the sweep gas up high and unattended as there is a potential risk of gas passing into the blood stream when the sweep gas is increased. If this incident is suspected turn the sweep gas down immediately.  

Heparin coating - these membranes are heparin coated to reduce clot activation on the large surface area of the membrane. This coating lasts for up to 24 hours and may result in lower rates of heparin infusion at this time as the heparin leeches from the membrane surface. Please use the out of protocol prescription if using less than 15 units of heparin. This should be documented in the electronic care record. 

Always follow the general membrane oxygenator guidelines. 

'Rated flow' = maximal flow of 75% saturated blood which can be fully oxygenated. Potential for C02 exchange is higher. Plasma tight hollow fibre membranes.

References

Reference 1: 
Chalice Medical (2009) Products. www.chalicemedical.com. Viewed on: 22/10/2012.

Reference 2: 
Maquet Cardiopulmonary (2009) Products - Quadrox Oxygenator. www.maquet.com. Viewed on: 22/10/2012. 

 

Document control information

Lead author
Maura O'Callaghan, ECMO Co-ordinator, ECMO

Additional authors
Liz Smith, Lead Nurse ANP, Cardiac ANP

Document owner 
Maura O'Callaghan, ECMO Co-ordinator, ECMO

Approved by
Clinical Practice Committee

First introduced: 2 April 2001
Date approved: 5 July 2012
Review schedule: Two years
Next review: 5 July 2014
Document version: 3.0
Replaces version: 2.0