27 1

extubation in ITU, surely the LMA could be used yet again to secure the airway and aid intubation. Cairns Base Hospital, Cairns 4870, Queensland, Australia

References [ I ] CHADD GD, ACKERSJ, BAILEYP. Difficult intubation aided by the laryngeal mask airway. Anaesthesia 1989; 44: 1015. J . BRIMACOMBE [2] HEATHML. Endotracheal intubation through the laryngeal mask - helpful when laryngoscopy is difficult or dangerous. European Journal of Anaesthesiology 1991; Suppl4: 41-5. [3] OH TE. Intensive care manual, 2nd edn. Sydney: Butterworths, 1985: 84-5.

Rectus sheath and mesosalpinx block for laparoscopic sterilisation We read with interest the technique of mesosalpinx block for pain after laparoscopic sterilisation described by Smith and his colleagues (Anaesthesia 1991; 46: 875-7). The technique appears very similar to that described by Alexander et al. [I], who found that bupivacaine infiltration of the mesosalpinx significantly reduced the pain after Yoon (Falope) ring sterilisation. Our own study that year [2] showed that ring sterilisation was followed by significantly more pain than Hulka clip sterilisation during the first 6 h after operation. The pain associated with the Falope ring presumably arises from infarction of the tubal section drawn into the ring and/or the pull on the mesosalpinx drawn with it. The ring technique also highlights, however, the consequent destruction of a substantial length of the tube, often including the isthmoampullary junction, which leads to both functional loss and technical difficulty that undermine the chance of successful reversal of the sterilisation [3]. The ring method also occasionally results in tearing of the tube and mesosalpinx causing bleeding. The clip method is therefore to be preferred for reasons in addition to obviating any need for special analgesic technique. It would be more valuable to know whether the technique of mesosalpinx injection of local anaesthetic, with its small but potentially dangerous risk of bleeding, offers a benefit:risk advance in the operation of clip sterilisation. It would also be valuable to know whether this local anaesthetic technique reduces significantly the pain

which continues for up to 4 days postoperatively and may be caused by gas retention in the abdomen, particularly above the liver. This can be reduced by the simple expedient of leaving a tube drain in the abdomen through the laparoscopy puncture site for a few hours afterwards [4]. Department of Anaesthesia, J.I. ALEXANDER Bristol Royal Infirmary University of Bristol. M.G.R. HULL Department of Obstetrics and Gynaecology Bristol Maternity Unit, Bristol BS2 8EG References [I] ALEXANDER CD, WETCHLER BV, THOMPSON RE. Bupivacaine

infiltration of the mesosalpinx in ambulatory surgical laparoscopic tubal sterilisation. Canadian Anaesthetbts ’ Society Journal 1987; 34: 362-5.

[2] DOBBSFF, KUMAR V, ALEXANDER J1, HULLMGR. Pain after laparoscopy related to posture and ring versus clip sterilisation. British Journal of Obstetrics and Gynaecology 1987; 94:262-6. [3] BOECKXS, GORDTSS, BUYSE K, BROSENS I. Reversibility after female sterilization. British Journal of Obsferrics and Gynaecology 1986; 93: 83942.

[4] ALEXANDER JI, HULL MGR. Abdominal pain after laparoscopy: the value of a gas drain. British Journal of Obstetrics and Gynaecology 1987; 9 4 262-9.

A problem with the TEC 5 vaporizer

We wish to report a potential problem in the design of the Ohmeda Tec 5 vaporizer which may lead to the sudden loss of the total anaesthetic agent from the vaporizer. The Tec 5 is the latest addition to the Ohmeda line of anaesthetic agent vaporizers. It offers several distinct advantages over the Tec 4 in terms of ease of use, performance and safety features. In addition, the Tec 5 can accommodate a greater volume of the free anaesthetic agent (225 ml as compared with 90 ml for Tec 4), thus minimising the frequency of filling. Difficulties with filling the Tec 4 vaporizers [l] as well as leakage of anaesthetic agent from the drain port [2] have led to a unique keyed filling mechanism in the Tec 5 version. During an otherwise uneventful anaesthetic for an orthopaedic procedure in which the patient was breathing spontaneously, the filling port valve was accidentally brushed against whilst the patient’s case notes were being picked up from the anaesthetic table top. This flicked open the filling port valve, resulting in a large loss of the anaesthetic vapour, as reconstructed in Figure 1. The filling port valve, which is normally only opened during filling of the vaporizer, is not secured by a locking mechanism during routine use. The simple and obvious consequences of such large leaks include the exposure of the theatre personnel to anaesthetic vapours, loss of an expensive anaesthetic agent, possibility of anaesthesia becoming light, and damage to items on the anaesthetic table top. The potential for disaster is great, including the anaesthetist’s

Fig. 1.

Rectus sheath and mesosalpinx block for laparoscopic sterilisation.

Correspondence 27 1 extubation in ITU, surely the LMA could be used yet again to secure the airway and aid intubation. Cairns Base Hospital, Cairns...
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