A reply

Abstract

Thank you for giving me the opportunity to reply to Dr Vohra's letter regarding the difficulty experienced when mounting Datex-Ohmeda Tec 3 and Tec 5 vaporisers on a Flexima 1 anaesthesia workstation. We assembled an identical Flexima 1 workstation in our service centre using the vaporiser configurations shown in Dr Vohra's figures. The results obtained were the same as those reported by Dr Vohra. There was little room to place lifting fingers under either vaporiser, making the mounting operation very difficult. The Tec5 was an interference fit with the floor of the Seletatec mounting block tray. Clearly, the temptation under these circumstances is to grasp the vaporiser by the side faces at the point where the Tec 5 filler is located. This may result in an accidental opening of the drain control lever when the fingers are removed from the narrow gap between the two vaporisers. Picking up the vaporiser by the percentage control knob situated on the top of the vaporiser is similarly not recommended, particularly in the case of the Tec 3 where there is a direct link between the control knob and the rotary valve controlling the flow of anaesthetic agent. We asked Dameca, the manufactures of the Flexima 1 anaesthetic workstation, which vaporisers had been recommended by them for this machine when it was originally placed on the market? Dameca said that the original machines were manufactured to take the Datex-Ohmeda Tec 4 vaporisers, which are similar to the Tec 5 but much shorter. We fitted Tec 4 vaporisers to the Flexima 1 and found no difficulty in supporting the weight of the vaporiser from below without trapping fingers between the vaporiser bottom and the mounting block tray. Tec 3 vaporisers are not recommended for this machine and in fact cannot be fitted unless the lockout pins are removed from the backbar, an operation that we do not recommend. Dameca also advised that later versions of the Flexima 1 were manufactured with the backbar set higher above the mounting tray, permitting the satisfactory fitting of Tec 5 vaporisers. It may be possible to modify these earlier machines to the later standard. From our response you see that the compatibility of vaporiser to workstation is not a simple matter. We recommend that vaporisers of a type whose compatibility has been validated by the original manufacturer are used to avoid similar problems. Should the user wish to use alternative items they should ask their equipment supplier to confirm compatibility.