Correspondence

423

Fig. 1.

8 cm in length and with a 15 mm internal diameter produced by Siemens-Elema company was connected and sealed to the tube of the LMA through a 4-cm male-male connector prepared in our medical engineering department. This design of tube allows bending the part of the tube outside the mouth to any direction without obstruction (Fig. 1). We have had the opportunity to assess this prototype on 30 patients using both sizes and it has proved to be satisfactory. Insertion and correct placement of this type of LMA is easy to achieve. It can still be inserted by a blind technique. The shaft has to be grasped at the junction of the two tubes and pushed into the mouth with the usual recommended insertion technique. After insertion it is possible to strap the tube to the centre of the chin, the cheek, the forehead or to either side of the mouth, without

kinking. This eliminates the slight possibility of dislodgement. The connector between the two tubes gives strength to the tube and acts as a bite-block as it is opposite to the teeth for most patients. Therefore an additional airway or bite-block is not required. The new tube and the connector are autoclavable. We are conducting a larger study to include LMAs size 1 and 2 and the edentulous patients. Southampton General Hospital, M.Z. MICHEL Southampton SO0 4 X Y M.M. CROSSE References I . MANSONDG, BINGHAMRM. The laryngeal mask airway in children. Anaesthesia 1990; 4 5 760-3. 2 . BRAINAIJ. The laryngeal mask-a new concept in airway management. British Journal of Anaesthesia 1983; 55: 801-5.

Problems with the 32-gauge spinal catheter

We read with interest the evaluation of 32-gauge spinal catheters through 26-gauge needles by Drs Nagle, McQuay and Glynn (Anaesthesia 1990; 4 5 1052-4). We have also encountered several problems with the passage of this size catheter, particularly kinking and flattening of the catheter, which occluded the lumen, and complete breakage of the catheter close to the syringe end. The 32-gauge catheter is marked in centimetre increments, but the needle supplied in the Microspinal pack is not. This leads to difficulty in determining needle tip-toskin distance and therefore affects the accuracy of placing less than 2 cm of the catheter in the subarachnoid space. Marking the needle in 1 cm increments, as with the Tuohy extradural needle, would aid placement of the correct length of catheter in the space and would also help when

feeding the catheter during needle removal. We also encountered kinking of the catheter at the hub end of the needle during retraction of the needle over the catheter. Luckily, we were able to thread the needle over the kink in the catheter, and injection through it was not impeded. However, we later experienced a catheter problem which did result in inability to inject through it. In this case the catheter became flattened in a short segment, by being pinched between the syringe and the bed during transfer of the patient to the recovery room. This weakened the catheter, leading to breakage when attempting to straighten out the flattened segment. Altnagelvin Area Hospital, Londonderry BT47 ISB

E.P. McCoy

G. FURNESS

Safe use of propofol in a child with acute intermittent porphyria

I should like to present a report of the successful use of propofol for general anaesthesia in a child with acute intermittent porphyria. A 7-year-old girl, known to have intermittent porphyria, presented for tonsillectomy. She weighed 22.5 kg, was fit

and was not taking any medication. No premedication was given other than EMLA cream applied to the dorsum of the hand. In the anaesthetic room, routine monitoring of ECG, arterial blood pressure and pulse oximetry was started. A 22-gauge cannula was

Problems with the 32-gauge spinal catheter.

Correspondence 423 Fig. 1. 8 cm in length and with a 15 mm internal diameter produced by Siemens-Elema company was connected and sealed to the tube...
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