Correspondence one case with methohexitone and in the other with thiopentone. There were no untoward sequelae. Although the use of an antihistamine was clearly indicated, it was my clinical impression in both cases that recovery had already begun. Of the remaining patients in the series, not one showed a reaction to the test dose, nor-and this is the point-to the subsequent full induction dose. From time to time I observed the usual irritating side effects such as muscle movements and hiccups. (In passing, I have found a useful remedy for hiccups in a spontaneously breathing anaesthetised patient to be aspiration of air from the stomach via a nasogastric tube.) The choice of 0.25 ml as a test dose was arbitrary: it happens to be the least volume conveniently measured in and ejected from a 5 ml disposable syringe. It is ten to twenty times less than the customary adult induction dose. A smaller test dose is desirable: how small, it is not for me to say. However, would a lesser insult produce symptoms sufficient to alert the anaesthetist? Although one assumes hypersensitivity to be an ‘all or none’ phenomenon, there must be a minimum evoking stimulus. I also assume, rightly or wrongly, that the severity and persistence of any reaction might, to some extent, depend on the dose. Althesin is rapidly metabolised: a test dose of 0.25 ml, albeit large, seems not unreasonably large; it is certainly effective. If one accepts the hazard, the intravenous route does have one clear advantage over the intradermal : it is logistically easier, and therefore more likely to be employed as a routine. There is another advantage. The effect of an intravenous test dose on the patient’s level of consciousness is a guide to the induction dose itself. It has proved possible to reduce the manufacturer’s recommended dosage by 25 to 50%. Equally, if this is done, there is a corresponding reduction in the incidence and severity of dose-dependent side effects unrelated to hypersensitivity. In the combined data of Jago and Restall and myself (1300 cases) the incidence of Althesin hypersensitivity reactions is 1 :430-even greater than that of Evans & Keogh (1 : 1900). a figure which itself is under question as being an over-estimate. One is hard put to it to find a reason. Two of our three patients were known to have received Althesin in the past: and, of course, 1300 cases is a small number for adequate statistical analysis. We may never see another reaction in our lifetime, although I think that
87
over-optimistic. Althesin is an excellent anaesthetic agent in selected cases, and I would be very sorry to see it go. Perhaps Dr Whitwam is wise when he writes of Althesin (as it is presently formulated): ‘It is probable that the view taken by many anaesthetists will be that this drug has several desirable properties, and that on occasion these outweigh the occurrence of transient minor reactions, most of which require little or no therapy. However, it would appear that the frequency of hypersensitivity reactions to Althesin is much greater than with any other induction agent currently in use, and the decision to use this drug must remain a matter for personal j ~ d g e m e n t . ’ ~ Bror?i.sgro~eGeneral Ho~pital, Bronisgrorv, Worcs.
PETERV. ScorT
References 1 . FISHER, M . M c D . (1976) Intradernial testing after
servere histamine reactions to intravenous drugs used in anaesthesia. Anaesthesia and Intensiiv Care, 4,97. 2. LAURENCE, D . R . (1963) Clinical Pharmacology, 2nd edn. Churchill Livingstone, London. 3 . EVANS, J.M. & KEOGH, J . A . M . (1977) Adverse reactions to intraveneous anaesthetic induction agents. British Medical Journal 2, 735. 4. WHITWAM,J.G. (1978) Adverse reactions to intravenous induction agents. Brirish Jorirnnl o/’ Anaesthesia, 50, 677. A reply from Dr Jag0 and Dr Restall
Thank you for the opportunity to comment on Dr Scott’s letter. We agree intradermal skin testing is time-consuming, and that its introduction may not be greeted with great enthusiasm on a busy surgical ward. However, we do not think increased workload or staff prejudice can be allowed to obstruct patient safety. We had always believed that intravenous testing for histamine mediated reactions was contraindicated by the danger of overwhelming anaphylaxis, and are therefore most interested in Dr Scott’s experience of this technique. Clearly there is room for further debate on this subject, and we would value the views of other colleagues. Cambridge Military Hospital, Aldershot, Hunts.
R.H. JAGO J. RESTALL
A dangerous local anaesthetic spray
In 1973 Dr P.C. Liew described a case (Anaesthesia, 1973, 28, 346) in which the metal nozzle of a Xylocaine (lignocaine) spray made by Astra Laboratories, Ltd became detached during its use
to provide topical analgesia of the larynx and had to be retrieved from the carina. We would now like to report another case in which the nozzle of a similar spray become detached.
88
Correspondence
A 36-year-old women presented with low abdominal pain and a radiological examination of the colon revealed an intra-abdominal foreign body which looked like the nozzle of a Xylocaine spray. At laparotomy the nozzle was found to be lying partly in the caecum having perforated its wall. The patient recovered uneventfully. Her notes record that she had, 16 months earlier, undergone surgery for varicose veins and that the anaesthetist had, on that occasion, used a Xylocaine spray prior to intubation. We would like to emphasise the care which must be exercised when using this type of spray; it should be re-designed to prevent further mishaps of this nature. Hospital Priisado, Barrio Parqiw V. Sarsfii~ld, SO00 Cdrdoba, Argentina
A reply /i.oni Astra Liikemedd A B
We are grateful for the opportunity to comment on the letter from Drs J. Pogulanik and B.A. Castro. During the last years the spray nozzle described i n the letter from Drs J. Pogulanik and B.A. Castro has been substituted by a new type having a threaded portion of the tube within the plastic hub of thc spray bottle. Compared with the old design this modification has been found to safeguard the nozzle from coming loose. There are some countries, however, where this modification has not yet been introduced. One possible risk with the old type nozzle is that it may partially melt the plastic hub material if introduced into the hub hole immediately after heat sterilization, causing an enlargement of the hub hole and hence reduced retention of the nozzle. A new J. POGULANIK delivery system (without freon propellant) is being B.A. CASTRO developed and all attention will be given to ensure safety in clinical use. Astra Lakemedel A B, S-IS18.5 Scdertiilje, Sweden
ANDERS UPPFELDT (Information Manager)
Hazards of circle absorbers Rebreathing circle absorber systems offer advantages in economy, lack of pollution and (perhaps less importantly now), explosion hazards. In contrast to Britain, they are widely used in Australasia. Hazards of their use are numerous. The misconnection of the rebreathing bag to the inspiratory port,’ the expiratory port,2 and failure to vent excess gas when connected to a ventilator3 all lead to covert increase in circuit pressure and pneumothorax. Contamination of the circuit with soda lime has also long been recognised but two recent reports from North America emphasise that this problem has not been overcome. The one was due to design fault (with fresh gas flow coming in at the base of the a b ~ o r b e r ) , ~ the other to a routine testing procedure of overdistension of the rebreathing bag.’ This latter manoeuvre is recommended by the Royal Australasian College of Surgeons6 as part of the preanaesthetic ‘cockpit check’. Unidirectional valves have also been shown to be a problem and two cases of ‘to and fro’ rebreathing due to poorly re-assembled valves were recently rep~rted.’.~ I can find no reports in the recent literature of a valve dome which spontaneously disintegrated (Fig. 1). There was no immediate preceding trauma to the dome. It had appeared to be sound and had passed the ‘cockpit check’ test of the breathing circuit, before use.6 Internal pressure would be minimal as the patient was holding the mask in preoxygenation for a Caesarean Section. There was
nobody near the valve when it failed. It will be noted, however, that the valve dome is of an older type (here from a Boyle Mk. 2 absorber), many of which are still in use although the modern dome is made of plastic. The immediate tell-tale sign here was the tinkling of the broken glass. The deflation of the rebreathing bag in spontaneous respiration or the respiration or the loss of pressure during IPPV should be readily apparent. Department of Anaesthetics, Waikato Hospital, Hamilton, New Zealand
D.R. DERBYSHIRE
References
I . BARAKA, A. (1975) Misconnection of Boyle Circuit Tubings. Anaesthesia and Intensive Care, 3, 260. 2. RINGROSE. N.H. (1974) Design of Boyle Absorber. Anaesthesia and Intensive Care, 2, 269.
3. SEARS, B.E. & BOCAR, N.D. (1977) Pneumothorax resulting from a closed Anaesthesia Ventilator Port. Anethesiolngy, 47, 31 1 . 4. LAURIA, J.I. (1975) Soda lime dust contamination of breathing circuits. Anesthesiology, 47, 628. 5 . DEBBAN, D.G. & BEDFORD,
R.F. (1975) Overdistension of the rebreathing bag a hazardous test for circle system integrity. Anesthesiology, 42, 356. 6. MAINLARD, J. & DUDLEY, H. (1976) Safety in the Operating Theatre, 1st edn, p. 88. Edward Arnold, Melbourne.
87
over-optimistic. Althesin is an excellent anaesthetic agent in selected cases, and I would be very sorry to see it go. Perhaps Dr Whitwam is wise when he writes of Althesin (as it is presently formulated): ‘It is probable that the view taken by many anaesthetists will be that this drug has several desirable properties, and that on occasion these outweigh the occurrence of transient minor reactions, most of which require little or no therapy. However, it would appear that the frequency of hypersensitivity reactions to Althesin is much greater than with any other induction agent currently in use, and the decision to use this drug must remain a matter for personal j ~ d g e m e n t . ’ ~ Bror?i.sgro~eGeneral Ho~pital, Bronisgrorv, Worcs.
PETERV. ScorT
References 1 . FISHER, M . M c D . (1976) Intradernial testing after
servere histamine reactions to intravenous drugs used in anaesthesia. Anaesthesia and Intensiiv Care, 4,97. 2. LAURENCE, D . R . (1963) Clinical Pharmacology, 2nd edn. Churchill Livingstone, London. 3 . EVANS, J.M. & KEOGH, J . A . M . (1977) Adverse reactions to intraveneous anaesthetic induction agents. British Medical Journal 2, 735. 4. WHITWAM,J.G. (1978) Adverse reactions to intravenous induction agents. Brirish Jorirnnl o/’ Anaesthesia, 50, 677. A reply from Dr Jag0 and Dr Restall
Thank you for the opportunity to comment on Dr Scott’s letter. We agree intradermal skin testing is time-consuming, and that its introduction may not be greeted with great enthusiasm on a busy surgical ward. However, we do not think increased workload or staff prejudice can be allowed to obstruct patient safety. We had always believed that intravenous testing for histamine mediated reactions was contraindicated by the danger of overwhelming anaphylaxis, and are therefore most interested in Dr Scott’s experience of this technique. Clearly there is room for further debate on this subject, and we would value the views of other colleagues. Cambridge Military Hospital, Aldershot, Hunts.
R.H. JAGO J. RESTALL
A dangerous local anaesthetic spray
In 1973 Dr P.C. Liew described a case (Anaesthesia, 1973, 28, 346) in which the metal nozzle of a Xylocaine (lignocaine) spray made by Astra Laboratories, Ltd became detached during its use
to provide topical analgesia of the larynx and had to be retrieved from the carina. We would now like to report another case in which the nozzle of a similar spray become detached.
88
Correspondence
A 36-year-old women presented with low abdominal pain and a radiological examination of the colon revealed an intra-abdominal foreign body which looked like the nozzle of a Xylocaine spray. At laparotomy the nozzle was found to be lying partly in the caecum having perforated its wall. The patient recovered uneventfully. Her notes record that she had, 16 months earlier, undergone surgery for varicose veins and that the anaesthetist had, on that occasion, used a Xylocaine spray prior to intubation. We would like to emphasise the care which must be exercised when using this type of spray; it should be re-designed to prevent further mishaps of this nature. Hospital Priisado, Barrio Parqiw V. Sarsfii~ld, SO00 Cdrdoba, Argentina
A reply /i.oni Astra Liikemedd A B
We are grateful for the opportunity to comment on the letter from Drs J. Pogulanik and B.A. Castro. During the last years the spray nozzle described i n the letter from Drs J. Pogulanik and B.A. Castro has been substituted by a new type having a threaded portion of the tube within the plastic hub of thc spray bottle. Compared with the old design this modification has been found to safeguard the nozzle from coming loose. There are some countries, however, where this modification has not yet been introduced. One possible risk with the old type nozzle is that it may partially melt the plastic hub material if introduced into the hub hole immediately after heat sterilization, causing an enlargement of the hub hole and hence reduced retention of the nozzle. A new J. POGULANIK delivery system (without freon propellant) is being B.A. CASTRO developed and all attention will be given to ensure safety in clinical use. Astra Lakemedel A B, S-IS18.5 Scdertiilje, Sweden
ANDERS UPPFELDT (Information Manager)
Hazards of circle absorbers Rebreathing circle absorber systems offer advantages in economy, lack of pollution and (perhaps less importantly now), explosion hazards. In contrast to Britain, they are widely used in Australasia. Hazards of their use are numerous. The misconnection of the rebreathing bag to the inspiratory port,’ the expiratory port,2 and failure to vent excess gas when connected to a ventilator3 all lead to covert increase in circuit pressure and pneumothorax. Contamination of the circuit with soda lime has also long been recognised but two recent reports from North America emphasise that this problem has not been overcome. The one was due to design fault (with fresh gas flow coming in at the base of the a b ~ o r b e r ) , ~ the other to a routine testing procedure of overdistension of the rebreathing bag.’ This latter manoeuvre is recommended by the Royal Australasian College of Surgeons6 as part of the preanaesthetic ‘cockpit check’. Unidirectional valves have also been shown to be a problem and two cases of ‘to and fro’ rebreathing due to poorly re-assembled valves were recently rep~rted.’.~ I can find no reports in the recent literature of a valve dome which spontaneously disintegrated (Fig. 1). There was no immediate preceding trauma to the dome. It had appeared to be sound and had passed the ‘cockpit check’ test of the breathing circuit, before use.6 Internal pressure would be minimal as the patient was holding the mask in preoxygenation for a Caesarean Section. There was
nobody near the valve when it failed. It will be noted, however, that the valve dome is of an older type (here from a Boyle Mk. 2 absorber), many of which are still in use although the modern dome is made of plastic. The immediate tell-tale sign here was the tinkling of the broken glass. The deflation of the rebreathing bag in spontaneous respiration or the respiration or the loss of pressure during IPPV should be readily apparent. Department of Anaesthetics, Waikato Hospital, Hamilton, New Zealand
D.R. DERBYSHIRE
References
I . BARAKA, A. (1975) Misconnection of Boyle Circuit Tubings. Anaesthesia and Intensive Care, 3, 260. 2. RINGROSE. N.H. (1974) Design of Boyle Absorber. Anaesthesia and Intensive Care, 2, 269.
3. SEARS, B.E. & BOCAR, N.D. (1977) Pneumothorax resulting from a closed Anaesthesia Ventilator Port. Anethesiolngy, 47, 31 1 . 4. LAURIA, J.I. (1975) Soda lime dust contamination of breathing circuits. Anesthesiology, 47, 628. 5 . DEBBAN, D.G. & BEDFORD,
R.F. (1975) Overdistension of the rebreathing bag a hazardous test for circle system integrity. Anesthesiology, 42, 356. 6. MAINLARD, J. & DUDLEY, H. (1976) Safety in the Operating Theatre, 1st edn, p. 88. Edward Arnold, Melbourne.
