798
Correspondence
analgesia and this was personally demonstrated by transfixing a fold of skin in the back of her hand with a needle. She concluded that pain felt was related to the anticipation of this. On admission, ward sister noted how tranquil she was. She required no drug premedication and used autohypnosis to induce sleep during her hospital stay. DAVIDL. SCOTT
Whiston Hospital, Lancashire
Althesin-benzodiozepine
potentiation for intravenous anaesthesia
In their article on intravenous anaesthesia by infusion, Savege and his co-workers (Anaesthesia, 1975, 30, 757) commented on the occurrence of movement in a non-negligible percentage of their patients. I would like to venture a suggestion as a means of improving the operating conditions in non-paralyzed patients. In 1974, Gyermek reported' a series of animal experiments showing a marked potentiation of steroid anaesthetics by benzodiazepines. This potentiation can usefully be applied in clinical practice; my experiences in minor surgery have been very encouraging, and it has been possible to use a similar method for longer operations. The number of these cases is at present too small to allow definite conclusions to be drawn. In minor surgery, induction of anaesthesia is accomplished with Althesin 3-4 ml and diazepam 5 mg, given either from a single syringe or separately. Provided both drugs are given very slowly (induction in not less than 2 minutes) excellent operating conditions can be obtained for 5-8 minutes, without any other supplement. Should the procedure be longer than expected, further small increments of althesin (0.5-1 ml) are effective. Recovery is little delayed with this method. For longer operations, it is preferable to add a second 5 mg dose of diazepam about 10 minutes after induction, and an analgesic such as pentazocine which in spontaneously breathing patients appears to be less depressant, especially in repeated doses, than either pethidine or fentanyL2 The need for an increment of Althesin is indicated by an increase in ventilation, which precedes the onset of movement; if this sign is carefully observed it is possible to avoid movement during moderately long procedures. Hence, it is advisable to keep an Althesin syringe ready even if a continuous infusion is used, for, should the drip rate be inadequate, it is unlikely that enough Althesin can be given in time when the increased ventilation is noticed with the usual flow rates which can be obtained with indwelling needles. As an estimate, 10 ml Althesin (total dose, i.e. induction dose plus increments) are sufficient to maintain anaesthesia for some 30 minutes in an average adult. Recovery is understandably longer than with Althesin alone, especially when a potent analgesic agent has also been given. It does not seem that premedication with diazepam can produce a degree of potentiation similar to that obtained with intravenous administration at induction. Two of the patients recorded by Savege et al. (Anaesthesia, 1975,30,757) received diazepam 20 mg before operation but the authors did not mention any improvement in operating conditions attributable to premedication. Avenue des Mousq~ines20, 1005 Lausanne, Switzerland
PIERRE SUPPAN
References 1. GYERMEK, L. (1974) Benzodiazepines for supplementing steroid anesthesia. LifeSciences, 14,1433. 2. DAVIE, I., SCOTT, D.B. & STEPHEN, G.W. Respiratory effects of pentazocine and pethidine in patients anaesthetized with halothane and oxygen (1970). British Journal of Anaesthesia, 42, 113.
Correspondence
analgesia and this was personally demonstrated by transfixing a fold of skin in the back of her hand with a needle. She concluded that pain felt was related to the anticipation of this. On admission, ward sister noted how tranquil she was. She required no drug premedication and used autohypnosis to induce sleep during her hospital stay. DAVIDL. SCOTT
Whiston Hospital, Lancashire
Althesin-benzodiozepine
potentiation for intravenous anaesthesia
In their article on intravenous anaesthesia by infusion, Savege and his co-workers (Anaesthesia, 1975, 30, 757) commented on the occurrence of movement in a non-negligible percentage of their patients. I would like to venture a suggestion as a means of improving the operating conditions in non-paralyzed patients. In 1974, Gyermek reported' a series of animal experiments showing a marked potentiation of steroid anaesthetics by benzodiazepines. This potentiation can usefully be applied in clinical practice; my experiences in minor surgery have been very encouraging, and it has been possible to use a similar method for longer operations. The number of these cases is at present too small to allow definite conclusions to be drawn. In minor surgery, induction of anaesthesia is accomplished with Althesin 3-4 ml and diazepam 5 mg, given either from a single syringe or separately. Provided both drugs are given very slowly (induction in not less than 2 minutes) excellent operating conditions can be obtained for 5-8 minutes, without any other supplement. Should the procedure be longer than expected, further small increments of althesin (0.5-1 ml) are effective. Recovery is little delayed with this method. For longer operations, it is preferable to add a second 5 mg dose of diazepam about 10 minutes after induction, and an analgesic such as pentazocine which in spontaneously breathing patients appears to be less depressant, especially in repeated doses, than either pethidine or fentanyL2 The need for an increment of Althesin is indicated by an increase in ventilation, which precedes the onset of movement; if this sign is carefully observed it is possible to avoid movement during moderately long procedures. Hence, it is advisable to keep an Althesin syringe ready even if a continuous infusion is used, for, should the drip rate be inadequate, it is unlikely that enough Althesin can be given in time when the increased ventilation is noticed with the usual flow rates which can be obtained with indwelling needles. As an estimate, 10 ml Althesin (total dose, i.e. induction dose plus increments) are sufficient to maintain anaesthesia for some 30 minutes in an average adult. Recovery is understandably longer than with Althesin alone, especially when a potent analgesic agent has also been given. It does not seem that premedication with diazepam can produce a degree of potentiation similar to that obtained with intravenous administration at induction. Two of the patients recorded by Savege et al. (Anaesthesia, 1975,30,757) received diazepam 20 mg before operation but the authors did not mention any improvement in operating conditions attributable to premedication. Avenue des Mousq~ines20, 1005 Lausanne, Switzerland
PIERRE SUPPAN
References 1. GYERMEK, L. (1974) Benzodiazepines for supplementing steroid anesthesia. LifeSciences, 14,1433. 2. DAVIE, I., SCOTT, D.B. & STEPHEN, G.W. Respiratory effects of pentazocine and pethidine in patients anaesthetized with halothane and oxygen (1970). British Journal of Anaesthesia, 42, 113.
