When introduced to the UK in the 1980s, pump therapy soon fell into disrepute owing to a perceived increased risk of diabetic ketoacidosis (DKA), in some cases fatal, associated with pump failure. As insulin pump therapy has established itself as an effective way of optimising intensive insulin therapy, the apparent reliability of modern insulin pumps could be taken for granted. Certainly, the evidence no longer indicates that pump therapy is associated with an increased risk of DKA.
Pump failure, however, still occurs and minimising the risk of adverse outcomes when this does happen is dependent on effective blood glucose monitoring and regularly reinforcing advice on how to respond to pump failure.
Three of the papers summarised alongside highlight some common themes. Ross and colleagues report from four centres in New Zealand, with 83 adult and 92 paediatric pump users responding to their survey covering the year 2014, 86% of whom were using an Animas pump. Rabbone and colleagues report data obtained from 1574 paediatric pump users in 40 Italian centres using an electronic record form covering 2013. 29.2% were using the Animas Vibe pump and 34.4% the Medtronic Veo. Guenego and colleagues report from a single French centre on 350 new pumps provided to 174 patients from 2008 to 2013, comparing their findings to a previous survey from 2001 to 2007. 69% of these pumps were Medtronic and 21% Animas.
Ross et al looked broadly at adverse events related to pumps, with 3.42 reported per 100 person-years. Of these adverse events, 17 (9.8%) resulted in hospitalisation. Sixteen of these were due to DKA or elevated ketones, but 13 of these 16 were related to infusion set or site problems, not pump failure. Guenego et al reported 33 malfunctions per 100 pump-years. Of these malfunctions, 19% were classified as severe pump failures – either complete failure or an alarm indicating that the pump should be replaced. Of these severe failures, 13% resulted in episodes of hyperglycaemia, equivalent to 0.471 per 100 person-years, but no cases of ketosis or hospitalisation.
Guenego et al reported 33 replacement pumps needed per 100 pump-years – equivalent to the malfunction rate. This appears to reflect a different support system in France, where national policy requires that pump users do not contact manufacturers for technical support. Instead a non-profit organisation provides 24/7 technical support, reviewing all malfunctions and returning the offending pump to the manufacturer for replacement. This appears to result in a high replacement rate and a short pump life, with a median survival time of 26 months (interquartile range, 16–39). Complete failures occurred earlier, with a median life of 13.5 months for these pumps. Pump failures were more likely for female users and those under 40.
Pump replacement rates in the other studies were remarkably similar – 16.1 per 100 person-years in New Zealand and 16.5 per 100 person-years in Italy. Accidental pump damage was responsible for 28.6% of replacements in New Zealand and 28.5% in Italy. In Italy, the mean lifetime of the device was 2.92±2.07 years, 62.3% of pump failures occurred after at least 2 years, and the Animas Vibe and Medtronic Veo more commonly failed than other pumps. None of the studies found any relationship between pump failures and duration of diabetes or metabolic control.
These studies highlight that pump failures are not uncommon, but, in these centres, they were very rarely associated with any adverse clinical effect. The importance of education, and re-education, to ensure users are alert to the possibility of pump failure, how to identify it and what action to take if it occurs, is paramount. The French centre with no serious clinical sequelae from pump failures has a 24/7 on-call medical service. Centres should consider how best to support those on any intensive insulin regimen when it fails to control blood glucose levels adequately. Finally, regular review of the functioning components of the pump should be a routine aspect of pump care, and users should be specifically advised to inspect these components after any impact or contact with water.
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