Patient selection

Eligibility for VV ECMO

Summary page of patient selection for VV ECMO

For general principles of timing of ECMO and patient selection see

• When to think about ECMO
• Principles of patient selection

The likelihood of a patient receiving benefit from the application of VV ECMO for respiratory failure depends on age, diagnostic category/cause of respiratory failure, associated acute and chronic organ failures. VV ECMO needs to be initiated before established multi-organ failure. The chart below displays eligibility to guide the physician at the bedside.

Essential considerations regarding the clinical application of VV ECMO in adult populations

• The primary purpose of VV ECMO is to allow safe lung ventilation and to cease injurious lung ventilation
• Hypoxaemia and hypercarbia are largely correctable with VV ECMO however the threshold of this intervention and effect on mortality and morbidity are less certain
• Parenchymal lung pathology commonly requires support over long periods with the associated risk of further complications and needs to be considered in the patient context
• VV ECMO presents significant modifiable risks to patients and high healthcare care resource utilization and must be administered only by trained, credentialed and fully equipped staff

In order to assist with assessing patient eligibility, a chart has been provided to graphically represent the interaction of patient and disease factors.

Steps to use chart

• Determine diagnostic group (score 1, 2 or 3)
• Determine presence of modifying acute (score +1) and chronic illness (score +1)
• Calculate combined score (1-5)
• Make sure there are no absolute contraindications
• Use chart to observe eligibility and expected benefit from ECMO

Once established that the patient is eligible for VV ECMO, proceed to the next section on clinical triggers for more details on the timing of initiation of VV ECMO. Eligibility and timing should be discussed with the senior ECMO clinician on call 24/7.

Diagnostic groups

Diagnoses are ordered according to commonly associated outcomes with VV ECMO into ‘Favourable’, ‘High Risk’ and ‘Unfavourable’ pathologies. These are related to the reversibility and treatability of the condition. Chronic respiratory failure is assessed separately in the next section.

Favourable Diagnostic Categories (Score =1)

• Community acquired pneumonia (infective cause), COVID-19 – separate chart
• Aspiration pneumonitis
• Status Asthmaticus
• Primary graft dysfunction following lung transplant within 7 days
• Adult respiratory distress syndrome (ARDS) from drowning or transfusion

High Risk Diagnostic Categories (Score =2)

• Necrotising pneumonia or focal infective lung disease
• Pulmonary vasculitis (Goodpasture’s, ANCA-associated, other autoimmune)
• Lung transplant recipient 7-30 days post transplant
• Traumatic injuries
  • Moderate TBI, hypoxia from chest injury to allow assessment
  • Bronchial tear with air leak and hypoxia
  • ARDS form direct chest trauma
• Drug/toxin related pulmonary disease

Unfavourable Diagnostic Categories (Score =3)

• ARDS from non-pulmonary cause (e.g. burns, pancreatitis, infection)
• Invasive aspergillosis
• Pneumocystis jirovecii pneumonia
• Lung transplant recipients >30 days and suitable for re-transplantation (see also bridge to transplant)

Note: Chronic lung disease for bridge to lung transplant and periprocedural indications are not included here.

Clinical modifier

The comorbidities of the patient and the acute clinical state of the patient are modifiers of the patient outcome and taken into consideration here.

Increase score by one for the presence of chronic or acute modifiers. If both acute and chronic modifiers are present increase score by two.

Chronic (comorbidities) – one or more present add one to score (Score +1)

• Peripheral vascular disease (symptomatic, revascularised or amputation)
• Previously known ischaemic heart disease or prior revascularisation
• Moderate COPD (GOLD Stage II, FEV1 50-80%)
• Chronic renal failure stage 3 or 4 CKD (eGFR 60-15)
• Chronic liver disease
• Long term immunosuppression

Acute clinical condition – one or more present add one to score (Score +1)

• Lactate ≥5
• Noradrenaline ≥ 0.3 mcg/KG/min
• Ischaemic hepatitis defined by AST or ALT >1000, or, INR >2.0
• Anuria >4 hours

Absolute contraindication

Lung disease

• Severe chronic lung disease (see below bridge to transplant)
• Acute/ subacute pulmonary fibrosis likely cause of respiratory failure
  • Previous known/treated SLE, extra-articular Rheumatoid Arthritis, Scleroderma, Dermatomyositis, Sarcoidosis
  • Clinical course or pathological investigations suggestive of irreversible process (e.g. bleomycin lung injury)
• Obliterative bronchiolitis is the likely cause of respiratory failure*
• Graft versus host lung disease

*Severe acute restrictive lung disease with relatively clear CXR (early) is suggestive of cryptogenic organizing pneumonia (bronchiolitis obliterans with organizing pneumonia) and biopsy should be performed prior to instituting ECMO to distinguish from obliterative bronchiolitis.

Patient profile

• Age >75
• Bone marrow transplant recipients
• Terminal illness or non-treatable malignancy
• Liver cirrhosis Child-Pugh B or C or jaundice/ ascites/ encephalopathy
• Severe brain injury
• Severe cardiac disease, cardiomyopathy (VAD or inotropes)
• Chronic renal failure CKD 5 or dialysis
• ECMO initiation would not be in keeping with known patient wishes or that of the patient’s medical treatment decision maker (MTDM)

Acute condition

• Pulmonary oedema for LVF – consider VA ECMO
• Septic shock with hypoxia predominant presentation rather than pulmonary infiltrates
• Advanced microcirculatory failure with severe mottling or established purpura

Summary patient selection

Specific circumstances

Trauma

There are high-risk patterns of trauma patients that can have favourable outcomes in younger patients. The indication for ECMO however still needs to be made in the patient context and co-morbidity need to be considered.

• Bronchopleural fistula or disruption with inadequate ventilation (Use of ECMO indicated early!)
• Severe chest trauma with either failure to safely oxygenate or ventilate
• Mild or moderate TBI with a chest injury where key targets of ICP management PaCO2 and PaO2 can not be met

Indications above where there are complicating factors, these require expert input and opinion and include

• Any severe TBI
• Atlanto-occipital dissociation
• Concurrent bleeding

Clinical triggers and timing of VV ECMO

Respiratory Failure

VV ECMO is considered when unable to maintain SaO2 >88% or pH >7.20 (in hypercapnoeic respiratory failure) with safe mechanical ventilation settings (Plateau Pressure ≤32 and Tidal Volume ≤6 ml/Kg (PBW)) despite consideration of the following:

• Trial of high PEEP (18 – 22)
• Neuromuscular blocking agent infusion
• Consideration of trial of prone positioning
• Diuretic therapy (where appropriate)
• Consideration of recruitment maneuver (if not contraindicated)
• 2-12 hour trial of iNO or alternative pulmonary vasodilator (if available)
• Adequate cardiovascular support

Initiation is also considered when there is progressive barotrauma as a result of mechanical ventilation (pneumatocysts or pneumothoraces).

The following additional clinical and logistic factors must also be considered when determining the need for and the timing of ECMO:

• Rate of lung injury progression – Rapidly progressive (6-12 hours) lung infiltrates and increasing ventilator requirements particularly in the early stages of hospital admission are often associated with a fulminant illness that reduces the time window when ECMO may be of benefit
• Onset of secondary organ failures (renal failure, circulatory failure) with primary lung processes. The development of early renal failure or need for high dose vasoactive support secondary to respiratory failure may support earlier ECMO commencement
• The need for inter-hospital patient transportation. ECMO is currently considered the safest mode of respiratory support for unstable patients with severe respiratory failure requiring inter-hospital transport

The criteria used in the EOLIA trial are also useful however a referral should be made before the time frames expire.

• PaO2/FiO2 [P/F] ratio <50 mmHg for >3 hours
• P/F ratio of <80 mm Hg for >6 hours
• Arterial pH of <7.25 with a PaCO2 ≥60 mm Hg for >6 hours, with the respiratory rate increased to 35 breaths per minute and mechanical ­ventilation settings adjusted to keep a plateau pressure of ≤32 cm of water despite ventilator optimization (defined as a fraction of inspired oxygen [Fio2] of ≥0.80, a tidal volume of 6 ml per kilogram of predicted body weight, and a positive end­-expiratory pres­sure [PEEP] of ≥10 cm of water