Health in Wales



Clinical Access PolicyP41: Extracorporeal Membrane Oxygenation for the Treatment of non-H1N1 Acute Respiratory Distress Syndrome in AdultsFirst published: Status:DRAFTVersion:0.1Date:16.07.13Author: Dr Phil WebbPolicy StatementFunding for the treatment of non-H1N1 acute reversible respiratory distress syndrome by Extracorporeal Membrane Oxygenation (ECMO) in adult is not supported by the Welsh Health Specialised Services Committee.Rationale for Decision for non-H1N1 respiratory indicationsClinical EffectivenessThere is limited data of the effectiveness of ECMO and the available data is confounded due to the design of the studies available to date. Results from the CESAR trial, which is the most recent randomised control trial to date, demonstrated a trend towards improved survival using ECMO vs. conventional care in adults with severe acute respiratory failure, defined by a Murray Lung Injury Score >3.0. This trend was not statistically significant, which was consistent with two major previous trials published in 1979 and 1994.In the CESAR trial, however, ECMO was shown to be beneficial when survival without severe disability was substituted as the primary endpoint. This significance could be greatly influenced by missing data classifying the disability status data for three patients in the conventional management group. (These patients were simply lost to follow-up). However, as survival has not been shown to be significantly different between groups, it is hard to imagine why those who survive, post ECMO, do so with less severe disability.When recruiting subjects, the authors used the LIS described by Murray et al. rather than the definitions for acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) produced following a 1994 consensus conference, a Murray score >3 being the primary inclusion factor. This is not a concern given previous evidence that these scoring systems can be used interchangeably. It is worth noting that such scores have not been shown in clinical trials to be predictive of mortality in severe respiratory failure. It is therefore reasonable to assume that a validated, mortality predictive scoring system, if it existed, could stratify for inclusion in a study with mortality as one of the primary outcomes.Other confounding factors are evident when reviewing the pivotal study. Attention should be paid to statistically different rates of steroid use, low-volume ventilation and diuresis to dry weight between groups. These interventions were performed to a greater extent in the treatment limb and might be considered beneficial at various stages of lung injury. In particular, the beneficial effect of a low-volume ventilatory strategy has been well demonstrated to improve outcomes in ARDS. The detrimental effect of a relatively high-volume ventilation strategy in the conventional treatment group may even be significant enough to explain the relative benefit demonstrated in the treatment group.Another factor which may have had a significant effect was the use of a molecular albumin re-circulating system in the treatment limb. As a mode of therapy used to bridge patients until liver transplant, it would not appear to be of specific benefit in the setting of severe respiratory failure, but this does add another significant unknown factor, being used in 20% of patients in the ECMO limb.Cost EffectivenessIn terms of cost effectiveness, although the predicted lifetime incremental cost per QALY discounted at 3.5% was ?19,252 (95% CI ?7,622 to ?59,100), the mean health-care costs per patient were more than twice as high for the patients allocated to ECMO (?73,979) than for those allocated to CM (?33,435), a difference of ?40,544 (95% CI ?24,799 to ?56,288). Based on a simple budget impact analysis, and using the same costing assumptions listed above, the additional cost to the health service of a policy of providing access to the ECMO service would be for 5 adult patients ?201,179 (ECMO vs. CM). The base-case analysis (from the NHS viewpoint and so excluding patients’ costs) found the incremental cost-effectiveness of ICER of ECMO to be ?250,162 per additional survivor without severe disability. The mean gain in QALYs at 6 months post randomisation for those patients allocated to ECMO was 0.03 (95% CI 0.00 to 0.06) and the cost per additional QALY at 6 months post randomisation was ?1,631,124. The significant uncertainty around these ICER QALY estimates was highly reflective of the inconclusive data provided for clinical benefit and therefore, the lifetime ICER QALY estimate of ?19,252 carries significant uncertainty.Rationale for Non Respiratory IndicationsNo published data was found for cardiac or other non respiratory indications for ECMO in adults. DefinitionsExtracorporeal Membrane Oxygenation (ECMO) ECMO is a technique that oxygenates blood outside the body. It can be used in potentially reversible severe respiratory failure when conventional ventilation is unable to oxygenate the blood adequately. The aim of ECMO in respiratory failure is to allow the injured lung to recover whilst avoiding certain recognised complications associated with conventional ventilation. It is high risk and is therefore only used as a matter of last resort in difficult cases. The procedure involves removing blood from the patient, taking steps to avoid clots forming in the blood, adding oxygen to the blood and pumping it artificially to support the lungs.Acute Respiratory Distress Syndrome (ARDS) is a life-threatening medical condition where the lungs cannot provide enough oxygen for the rest of the body.ARDS can affect people of any age and usually develops as a complication of a serious existing health condition. Consequently, most people have already been admitted to hospital by the time the symptoms of ARDS begin.Symptoms and signs of ARDS can include:severe shortness of breath rapid, shallow breathing tiredness, drowsiness or confusion feeling faint Patient PathwayClinicians are advised to review the Protocol in Appendix 1 developed by the Wales Critical Care Network for the management of patients with ARDS.ExclusionsECMO for neonates is considered under a separate policy – see Policy XXX ................
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