The cardioplegia pump on the heart-lung machine accelerated uncontrollably during cardioplegia administration. Cardioplegia was administered through a twin-pump module on a Maquet HL20, one blood pump (master) and the other cardioplegia solution pump (slave). During this incident cardioplegia was being given via a vein graft to a coronary artery. The risk of an accelerating uncontrolled pump when delivering cardioplegia down this route is to damage the vessel it is being given down and/or damage to the vein graft to coronary artery suture site.
This is the units third such event in twelve months.
The cardioplegia pumps have the following alarms in place at all times:
In all of the units episodes (three episodes) there has been audible alarms either for Runaway or Pressure or both but the stop feature did not happen and in each episode the main power switch for that twin-pump module had to be turned off for the Runaway pump to be stopped. The same HLM was in use for each event operated by different perfusion scientists.
None, graft site re-checked by Consultant (SA) and confirmed as intact and undamaged.
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Firstly, the immediate and extremely swift action taken by the perfusionist prevented significant harm being caused to the patient. the presence of a colleague enabled the surgery to continue without delay. The surgeon was very supportive. There had been no deviation from Clinical Perfusion policy and all alarms had been set correctly. On seeing the analogue pressure gauge turning 'around the clock', thereby indicating a significant pressure increase in the cardioplegia circuit, she clamped the patient delivery line and switched off the main power switch to that twin-pump module. A second perfusionist was immediately called into theatre the decision to change out the twin-pump module from the heart-lung machine was taken. There was no interruption to surgery but a delay of several seconds for a fresh administration of cardioplegia. The surgeon was advised of the delay. Once completed, the surgeon was advised of the detail of the incident and he checked the vein graft to coronary artery suture site for any damage. This he was happy to do and confirmed that the site was undamaged and looked fine. The twin-pump has been quarantined and the manufacturer was contacted.
The pump was thoroughly checked by the servicing engineer, and no fault was identified.
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