Issue 131critical care ecmo

CLINICAL

Alice Lunt, RD Cardiorespiratory Dietitian, Royal Brompton Hospital, London Alice is an active member of the British Dietetic Association and Treasurer for the BDA’s Critical Care Specialist Group. She is also Health Advisor for the British Lung Foundation.

(Twitter @BdaCare and Facebook page)

REFERENCES For full article references please CLICK HERE . . .

CRITICAL CARE: FEEDING THE ADULT EXTRACORPOREAL MEMBRANE OXYGENATION PATIENT Extracorporeal membrane oxygenation (ECMO) is a highly specialised life support technique whereby a machine is able to temporarily support a person’s cardiac and/or respiratory systems after surgery or life-threatening illness. This may also be referred to as Extracorporeal life support (ECLS).

An ECMO machine is a form of temporary life support which uses a cardiopulmonary bypass circuit similar to the equipment used during a heart-lung bypass operation. There are two most common forms of ECMO, both of which involve blood being removed from the venous system and oxygenated outside the body.

• Venovenous (VV) ECMO is used for respiratory failure returning oxygenated blood to the venous system near the right atrium.

• Venoarterial (VA) ECMO is for those with severe cardiac failure; therefore, returns the oxygenated blood to the arterial system.

Royal Brompton and Harefield Trust (RBHT) is one of five commissioned centres nationwide funded to offer VV ECMO for adults with severe acute respiratory failure along with Guy’s and St Thomas’ Hospital NHS Foundation Trust (FT), Papworth Hospital NHS FT, University Hospitals of Leicester NHS Trust and University Hospital of South Manchester NHS FT.1 VA ECMO does not have the same commissioning process.

Patients needing specialist support are referred (see Table 1 overleaf) by other hospitals to the regional VV ECMO centre. Once recovered, patients return to the referring hospital for ongoing support and safe effective discharge home.

Figure1: VV and VA ECMO

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Intensive

High protein intensive enteral nutrition for the ICU For the dietary management of patients with or at risk of malnutrition, in particular critically ill patients including trauma, surgery, sepsis or burns. > > > >

1.2 kcal/ml tube feed 10g protein per 100ml Nutritionally complete in 1000ml Optimal ratio of energy to protein

Many complex patients Hundreds of drugs Various therapeutic pathways Bearing high level of responsibility Critical decisions to make

1 nutrition solution

For further information please contact Fresenius Kabi tel: 01928 533516 fax: 01928 533520 email: scientific.affairsUK@fresenius-kabi.com Date of preparation: June 2017 EN01360a

CLINICAL Table 1: Referral indicators and contraindications for VV ECMO retrieval1 Indications: Age ≥16 years Potentially reversible severe acute respiratory disease typically associated with severe hypoxaemia (e.g.

PaO2/FiO2 <13.3kPa), severe hypercapnic acidosis (e.g. pH<7.20) despite conventional support No limitation to ongoing life-sustaining treatment Murray score ≥3.0 (consider referral if ≥2.5 and rapid clinical deterioration) OR uncompensated hypercapnoea with pH <7.2 Adequate arterial blood gases cannot be achieved using lung protective tidal volumes and pressures Contraindications: Intracranial bleed (current or recent) High pressure (peak inspiratory pressure >30 cmH2O) and/or high FiO2 (>0.8) ventilation for more than seven days (relative contraindication) Other contraindication to heparinisation

RBHT uses a unique online system called ‘Hospital to home’ to support this process and to enable MDT discussions across both sites throughout a patient’s pathway.1 Hospital to home is aiming to be built upon and extended to VA ECMO in the not too distant future.

ECMO has been used increasingly in the past three decades; greatest demand was seen with the onset of swine flu in 2009, enabling the support of patients with severe cardiopulmonary failure who have been unresponsive to conventional therapies.1 Nutrition support for adults receiving ECMO has not been well researched or documented.

There are ASPEN Neonate ECMO guidelines, but only small scale retrospective observational studies on adults. With the absence of available guidelines, current practice for ECMO patients is thorough assessment and considerations similar to any critically ill patients, all of which will generally be based on an ICU. Nutrition is paramount to minimise catabolism and support recovery in critical illness. Sufficient nutritional support is associated with a reduced incidence of infections, costs and a length of ICU stay.2,3 Despite known benefits of nutritional support, meeting ICU patients’ requirements can be very difficult.3,4 FEEDING METHOD

Historically, concerns for the negative effects of enteral nutrition in patients receiving ECMO has led to withholding enteral nutrition in this patient group in many ICU centres.5 Anxieties 32

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continue to exist regarding the safety, timing and adequacy of nutrition in this patient group.

A recent retrospective local audit (presented at 2017 ESICM conference) of 80 patients at RBHT found that nasogastric feeding within 24 hours of initiating ECMO is safe and well tolerated.

These results are inline with current critical care guidance that enteral nutrition using a feeding tube and initiated within the first 24 to 36 hours is safe and well tolerated.6 Enteral nutrition is the preferred route, but parenteral nutrition should be initiated for supplementary or total nutrition provision when enteral nutrition is not adequate as per Table 2 overleaf.6 REQUIREMENTS

There are ongoing discussions within the critical care profession regarding methods of calculations and optimal macro and micro nutrient provision to aim for. The method or equations for calculating both energy and protein requirements tends to be centre specific regarding what equations should be used on which to base estimations.

INTACT trial 2014 found that early provision of higher energy and protein intakes predicted increased mortality risk in 78 patients with acute lung injury.7 Patients on ECMO are in an acute phase and highly catabolic phase of care.

Nevertheless, optimal outcomes are seen when relatively low protein and energy are provided for the first few days, increasing recognition that nutrition provision is beneficial, but not

Sufficient nutritional support is associated with a reduced incidence of infections, costs and a length of ICU stay. necessarily aiming to meet the full requirements.

There is a careful balance of not under-feeding, but also not over-feeding due to potential harm, such as increased ventilator requirements, deranged liver function and risk of ischaemic bowel. We currently build up intake over the first few days following admission, aiming to meet requirements by day three to four, increasing this further as the patient continues to recover and progresses towards rehabilitation.7 Protein requirements on ECMO are thought to be similar to other nutrient loss processes, such as renal replacement therapy or pressure ulcers.

Therefore, adequate protein is important and the use of both higher protein target intake and high protein feed formulations. Micronutrients or immune modulating agents have unknown impact, so regular monitoring and supplementing as indicated inline with all patient requirements is necessary. There is ongoing research into specific vitamins and minerals, for example, vitamin D supplementation in those who are deficient is thought to have positive outcomes.20 The microporous membrane in the oxygenator can be compromised by the accumulation and potential blockage by IV fat for example from parenteral nutrition. However, this complication is rare, hence why the anaesthetic propofol is frequently used for sedation. Propofolâ&#x20AC;&#x2122;s lipid solubility and quantities needed to support ECMO patients should be considered; calories from propofol may need to be accounted for at roughly 1.1kcal/ml.6 This in turn can compromise nutrition provision to avoid overfeeding of patients who are receiving both nutrition and propofol.

When considering nutrition support in the ICU, certain comorbidities should be taken into consideration, for example, pre-existing liver, gastrointestinal or renal dysfunction is an important aspect when contemplating nutrition support and can alter the choice of enteral nutrition formulas selected for delivery.

Obese patients also require high protein and relatively low energy provision as per ASPEN guidelines.8 Critical illness associated endocrine response in the form of insulin resistance and hyperglycaemia mean close monitoring of blood glucose levels and sliding scale insulin management is standard practice for all intensive care patients.6 GASTROINTESTINAL AND FEED TOLERANCE

Gut permeability and motility is a key concern as there is thought to be reduced gut perfusion and absorption. Gut motility can be compromised by heavy sedation and/or paralysis, therefore, laxatives are routinely given to ECMO patients.

Prokinetics are given when indicated, based on local gastric residual volume aspirates guidelines. However, one study found 95% of patients required prokinetics within the first 48 hours.9 Gut perfusion can be compromised for ECMO patients as a result of haemodynamic instability, fluid resuscitation, vasoactive agents, hypoperfusion, and cardiac failure. Therefore, ECMO can be associated with risk of mesenteric bowel ischaemia.

Feeding intolerance has been reported in up to 60% of patients in the ICU, as seen by gastrointestinal disturbance such as vomiting, diarrhea, or abdominal distension.10 Intolerance is thought to be multifactorial, with contributing factors including impaired function of the enteric nerve and smooth muscles of the gastrointestinal tract, inflammation, surgery, medications, electrolyte imbalances, hyperglycaemia, sepsis, increased cranial pressure and the presence of disease itself.10 The NUTRIREA 1 trial explored the effect of not monitoring residual gastric volume in adults receiving mechanical ventilation (MV) and early enteral feeding, and showed that there was no increase in the incidence of aspiration or related complications.11 A study found that up to 63% of www.NHDmag.com February 2018 - Issue 131

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CLINICAL Table 2: Audits of feeding methods for ECMO patients Audit

Patient requirements

Retrospective audit of 86 ECMO patients14

10% of patients needed TPN for three days or more.

80% of patients needed enteral nutrition every day for two weeks following admission.

Patients started on enteral nutrition had better tolerance of full enteral nutrition.

A retrospective study of 27 ECMO patients9

67% received solo enteral nutrition.

33% needed supplementary or TPN.

Table 3: Summary points 1. Follow critical care guidelines for nutrition support.

2. Initiate enteral nutrition and build up to target as tolerated.

3. Moderate provision of energy and protein depending on phase of care.

4. Close monitoring of biochemistry, medications, gastrointestinal function and clinical plan.

5. Supplement parenteral nutrition if needed.

patients receiving MV who had higher feeding infusion rates (>50ml/h) had diarrhoea, and for a longer duration.12 It has been reported that the motility of the upper gastrointestinal tract in patients receiving MV is severely impaired; contractile activity is completely lost in the stomach and diminished to a lesser degree in the duodenum.13 Furthermore, the safety of enteral feeding in severe respiratory failure patients, in particular those on ECMO, has been questioned.5 There is an increasing availability of different enteral formulas, differing in their protein, fibre and fat content, such as elemental, monomeric or polymeric. As with any feed intolerance, different feed formulations should be tried alongside medication optimisation and then, if needed, consideration of parenteral nutrition.

Significant underfeeding in critically ill patients in the ICU setting is reported, with patients receiving 52-76% of their daily dietary target, mainly due to gastrointestinal intolerance and elective withholding of feedings for procedures.3,4 An observational study looking at interruptions in enteral nutrition delivery and its impact on surgical patients, found that 26% of interruptions were deemed avoidable and underfeeding was associated with a longer length of stay.17 The critically ill state requiring additional ECMO support, together with underfeeding, can lead to malnutrition and significant muscle weakness. Survivors of critical illness experience significant skeletal muscle weakness and physical disability, which can persist for at least five years.18,19

FEED ADEQUACY

CONCLUSION

The majority of published ECMO studies look at nutrition provision and adequacy. A study of 48 ECMO patients15 found that: â&#x20AC;˘ 18% of nutritional requirements delivered during the first two days of admission increased to 30% when averaged over the first three days; â&#x20AC;˘ 55% of their nutritional target was achieved, which increased to 71% after the patients came off ECMO; â&#x20AC;˘ survival outcome was not associated with nutrition adequacy.

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In summary, a detailed thorough assessment and ongoing regular close monitoring is integral to nutrition support for ECMO patients, as it is for all critical care patients. ECMO is another form of mechanical support for patients and, therefore, it adds to nutritional demands and has a potential for complications. Open communication and close working with the multidisciplinary team is essential to optimise nutritional adequacy and therefore minimise malnutrition and its asociated short- and longterm complications.