(b)(4).The 900pt561 heated breathing tube (hbt) is used with the airvo humidifier to deliver warmed and humidified respiratory gases to spontaneously breathing patients through a variety of patient interfaces.Method: the complaint 900pt561 heated breathing tube is returned to fisher & paykel healthcare (f&p) in new zealand for evaluation, where it was visually inspected and resistance tested.Result: a visual inspection of the subject 900pt561 tube revealed that one area of the tube was damaged.The damage was melting of the plastic.It was also noted that the melted tubing had no signs of burning or smoke damage.Conclusion: based on our observations of previous damaged heated breathing tubes, the information provided by the customer, as well as the results of this investigation, the tube was very likely covered by material with a temperature greater than that of typical room conditions and is possible to have been under compressive load for a considerable length of time.It was also mentioned by the customer that the hbt was covered by the pillow during use.The airvo system is designed to comply with the electrical safety standard ul60601-1.The case is composed of a flame retardant material.The surface temperature of the heated breathing tube is within the limits specified by iso 8185 with regard to hot tube surface temperature not exceeding 44° celsius.There are many safety features incorporated into the airvo to prevent overheating and fire.These include: - the heater wires in the heated breathing tube are coated with teflon, completely insulating them from the gas path.- the pcb at the [patient] end of hose is over moulded with the thermoplastic polymer polypropylene, ensuring it is excluded from the gas path.- the airvo contains a transient current detector, tcd.This tcd is tested on the production line.It is also checked by the control system when the airvo is powering up before each use.- an 'over-temperature' sensor will automatically cut power to the motor, heater plate and heater wire if it detects any overheating.- the airvo is constantly checking power in the heated breathing tube and turns the heater wire off if the measured power is too high.The user instructions that accompany the airvo 2 humidifier include the following warning: adding heat, above ambient levels, to any part of the breathing tube or interface, e.G.Covering with a blanket, or heating it in an incubator or overhead heater for a neonate, could result in serious injury.The user manual instructs the user to "use continuous oxygen monitoring on patients who would desaturate significantly in the event of disruption to their oxygen supply." the user manual also states that the "airvo 2 is for the treatment of spontaneously breathing patients who would benefit from receiving high-flow, warmed and humidified respiratory gases." and that "the unit is not intended for life support".
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