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We would like to report a manufacturing fault in an anaesthetic breathing circuit that could easily be missed on a routine anaesthetic machine check. A new circle breathing circuit (Medi-limb circuit, Meditec Medical, Manchester, UK), taken from sealed packaging, was attached to a Datex-Ohmeda Aestiva 3000 (GE Healthcare, Pollards Wood, UK) anaesthetic machine during a routine circuit change. The machine was checked at the time of the circuit change and also the following morning by an operating department practitioner (ODP), but the machine was not used during the intervening time. On routine testing of the anaesthetic machine by an anaesthetist it was noted that whilst hand ventilation was possible, there was a marked increase in resistance to ventilation. On further investigation, it was found that the inner tube of the coaxial circuit was twisted and kinked, causing a fixed narrowing and obstruction to inspiratory flow (Fig. 4). This fault was difficult to see due to the coaxial nature of the circuit and the semi-opacity of the outer tubing. The inner tube is fixed during manufacture and is not free to rotate or twist, indicating that the fault must have occurred during manufacture. In this instance, the fault was noticed before clinical use, but we suggest that such an obstruction of the inspiratory tubing could be easily missed by both the Pethick and occlusion tests [1]. Indeed, the fault was missed by ODPs using these tests, and had the potential to lead to patient morbidity and even mortality. This problem reinforces the importance once again of the pre-operative anaesthetic machine check. The problem has been reported to the Medicines and Healthcare products Regulatory Agency and Meditec Medical.

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Figure 4.  Kinked inner tube visible with backlighting.

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