1267
CORRESPONDENCE Magill was perhaps too poetic for the humdrum English when he called it the position of sniffing the morning air. The position is illustrated more earthily on the backs of some of our buses, where the Bisto kids are shown getting a whiff of their scrumptious bottled gravy. Their cervical spines are flexed—straightened, for extension increases the curvature, and only the atlanto-occipital joints are extended. P. H. BEVES
Kidderminster
J. M. ANDERTON
Manchester REFERENCE
Dennison, P. H. (1978). Four experiences in intubation of one patient with Still's disease. Br. J. Anaesth., 50, 636.
JOSEPH A. STIRT
Los Angeles, California REFERENCES
Bonica, J. J. (1967). Principles and Practice of Obstetric Analgesia and Anesthesia, p. 579. Philadelphia: F. A. Davis Co. Boys, J. E. (1977). Analgesia in labour. Br. J. Anaesth., 49, 841. Galloon, S. (1978). Test doses in extradural analgesia. Br.J. Anaesth., 50,304. Scott, D. B. (1978). Test doses in extradural analgesia. Br.J. Anaesth., 50,304.
Downloaded from http://bja.oxfordjournals.org/ at University of Manitoba on June 23, 2015
Sir,—I have read Dr Dennison's letter on the use of the flexible fibreoptic laryngoscope with great interest. I have had some experience of using this instrument during the past year and although I share Dr Dennison's obvious enthusiasm, I have found that it takes considerable practice to become competent in its use. I would not advise anyone to rely on using it in a difficult situation without previous experience. (I note that Dr Dennison had performed 300 intubations with it before the case of Miss C. W.!) The size of the instrument causes two problems. First, the smallest diameter of nasal tube which will fit comfortably over it is 8.0 mm. This limits its use to older teenagers and adults. Second, it is sometimes not possible to pass it down either nostril, even in the adult. Occasionally the instrument will pass through the nose and into the trachea, but is such a tight fit in the nostril that the endotracheal tube will not pass through the nostril. In addition, vision is obscured frequently by the following: (1) Mist forming over the end-piece—this can be minimized by the use of an anti-misting substance. (2) Mucous, blood or lubricating jelly, which may be removed only by withdrawing the instrument and cleaning the tip. The presence of blood in the nostril can be a difficult recurring problem. Other factors which help to improve laryngoscopy with this.instrument are: (1) Adjustment of the focus of the eye-piece. After experimenting with different positions, I have found the midpoint of the range to be the most helpful. (2) Adequate pre-oxygenation of the patient before induction of anaesthesia prolongs the time available for intubation. Easy intubations may be accomplished within 60-90 s, but more difficult ones can take considerably longer. (3) An assistant holding the jaw forward allows an unimpeded view of the larynx which is otherwise obscured by the posterior aspect of the tongue. The image obtained of the larynx is tiny compared with the normal size seen by conventional laryngoscopy. Recognition of this and manoeuvre of the tip of the laryngoscope towards it are not difficult, but require practice. This instrument is undoubtedly a very significant addition to our armamentarium for the patient in whom endotracheal intubation is difficult.
TEST-DOSES I N EXTRADURAL ANALGESIA
Sir,—With regard to the recent controversy in your pages on test-doses in extradural analgesia (Boys, 1977; Galloon, 1978; Scott, 1978), I wish to report an episode of an extradural catheter migrating into the subarachnoid space. A 31-year-old female undergoing Caesarean section was placed in the left lateral position and a 17-G Tuohy needle was inserted at the L2-L3 interspace into the extradural space, using the loss of resistance test. A 19-G catheter was advanced into the extradural space. After inserting the catheter 5 cm cephalad, paraesthesiae were noted in the left leg. The needle and catheter were withdrawn simultaneously 1 cm and the paraesthesiae disappeared. The catheter was taped in place, and the patient was taken to the operating suite. She was placed in the sitting position, the catheter aspirated with no fluid return, and 2 ml of chloroprocaine 3% was injected easily. After 5 min, when no evidence of spinal block appeared, 14 ml of chloroprocaine 3% were injected over 1 min. The patient remained in the sitting position for 5 min, and was then placed supine. After 8 min, sensory analgesia was present bilaterally to T7 and the operation commenced. After negative aspiration (but without a test-dose) an additional 6 ml of chloroprocaine 3% was injected and the sensory block attained the level of T5. Ten minutes after the last injection, pink fluid was noted dripping from the end of the catheter at a rate of 1 drop every 3 s. Three millilitre of fluid was aspirated easily and testing was negative for glucose, but there was a trace of protein and blood. It was thought that the fluid was local anaesthetic, since its flow seemed to be affected by uterine manipulation. Nevertheless, a sample of the fluid and a quantity of chloroprocaine 3% were sent to the laboratory for measurement of glucose and protein concentration, and a venous blood sample was obtained for the measurement of blood glucose concentration. At the end of the procedure the patient showed no evidence of a spinal block and she had active toe movements bilaterally. The catheter was removed immediately and found to be intact. Two hours after termination of the procedure, results were available from the laboratory and they revealed: Catheter fluid: glucose 4.94 mmol litre"1, protein 0 Blood: glucose 8.44 mmol litre" 1 3% chloroprocaine: glucose 0.39 mmol litre"1, protein 0 These results suggest that the catheter had migrated into the dural canal while the patient was supine and immobile, even though such episodes may be "so infrequent" (Bonica, 1967). Thus it would appear that the use of a test-dose of local anaesthetic in continuous extradural analgesia is worth while.
CORRESPONDENCE Magill was perhaps too poetic for the humdrum English when he called it the position of sniffing the morning air. The position is illustrated more earthily on the backs of some of our buses, where the Bisto kids are shown getting a whiff of their scrumptious bottled gravy. Their cervical spines are flexed—straightened, for extension increases the curvature, and only the atlanto-occipital joints are extended. P. H. BEVES
Kidderminster
J. M. ANDERTON
Manchester REFERENCE
Dennison, P. H. (1978). Four experiences in intubation of one patient with Still's disease. Br. J. Anaesth., 50, 636.
JOSEPH A. STIRT
Los Angeles, California REFERENCES
Bonica, J. J. (1967). Principles and Practice of Obstetric Analgesia and Anesthesia, p. 579. Philadelphia: F. A. Davis Co. Boys, J. E. (1977). Analgesia in labour. Br. J. Anaesth., 49, 841. Galloon, S. (1978). Test doses in extradural analgesia. Br.J. Anaesth., 50,304. Scott, D. B. (1978). Test doses in extradural analgesia. Br.J. Anaesth., 50,304.
Downloaded from http://bja.oxfordjournals.org/ at University of Manitoba on June 23, 2015
Sir,—I have read Dr Dennison's letter on the use of the flexible fibreoptic laryngoscope with great interest. I have had some experience of using this instrument during the past year and although I share Dr Dennison's obvious enthusiasm, I have found that it takes considerable practice to become competent in its use. I would not advise anyone to rely on using it in a difficult situation without previous experience. (I note that Dr Dennison had performed 300 intubations with it before the case of Miss C. W.!) The size of the instrument causes two problems. First, the smallest diameter of nasal tube which will fit comfortably over it is 8.0 mm. This limits its use to older teenagers and adults. Second, it is sometimes not possible to pass it down either nostril, even in the adult. Occasionally the instrument will pass through the nose and into the trachea, but is such a tight fit in the nostril that the endotracheal tube will not pass through the nostril. In addition, vision is obscured frequently by the following: (1) Mist forming over the end-piece—this can be minimized by the use of an anti-misting substance. (2) Mucous, blood or lubricating jelly, which may be removed only by withdrawing the instrument and cleaning the tip. The presence of blood in the nostril can be a difficult recurring problem. Other factors which help to improve laryngoscopy with this.instrument are: (1) Adjustment of the focus of the eye-piece. After experimenting with different positions, I have found the midpoint of the range to be the most helpful. (2) Adequate pre-oxygenation of the patient before induction of anaesthesia prolongs the time available for intubation. Easy intubations may be accomplished within 60-90 s, but more difficult ones can take considerably longer. (3) An assistant holding the jaw forward allows an unimpeded view of the larynx which is otherwise obscured by the posterior aspect of the tongue. The image obtained of the larynx is tiny compared with the normal size seen by conventional laryngoscopy. Recognition of this and manoeuvre of the tip of the laryngoscope towards it are not difficult, but require practice. This instrument is undoubtedly a very significant addition to our armamentarium for the patient in whom endotracheal intubation is difficult.
TEST-DOSES I N EXTRADURAL ANALGESIA
Sir,—With regard to the recent controversy in your pages on test-doses in extradural analgesia (Boys, 1977; Galloon, 1978; Scott, 1978), I wish to report an episode of an extradural catheter migrating into the subarachnoid space. A 31-year-old female undergoing Caesarean section was placed in the left lateral position and a 17-G Tuohy needle was inserted at the L2-L3 interspace into the extradural space, using the loss of resistance test. A 19-G catheter was advanced into the extradural space. After inserting the catheter 5 cm cephalad, paraesthesiae were noted in the left leg. The needle and catheter were withdrawn simultaneously 1 cm and the paraesthesiae disappeared. The catheter was taped in place, and the patient was taken to the operating suite. She was placed in the sitting position, the catheter aspirated with no fluid return, and 2 ml of chloroprocaine 3% was injected easily. After 5 min, when no evidence of spinal block appeared, 14 ml of chloroprocaine 3% were injected over 1 min. The patient remained in the sitting position for 5 min, and was then placed supine. After 8 min, sensory analgesia was present bilaterally to T7 and the operation commenced. After negative aspiration (but without a test-dose) an additional 6 ml of chloroprocaine 3% was injected and the sensory block attained the level of T5. Ten minutes after the last injection, pink fluid was noted dripping from the end of the catheter at a rate of 1 drop every 3 s. Three millilitre of fluid was aspirated easily and testing was negative for glucose, but there was a trace of protein and blood. It was thought that the fluid was local anaesthetic, since its flow seemed to be affected by uterine manipulation. Nevertheless, a sample of the fluid and a quantity of chloroprocaine 3% were sent to the laboratory for measurement of glucose and protein concentration, and a venous blood sample was obtained for the measurement of blood glucose concentration. At the end of the procedure the patient showed no evidence of a spinal block and she had active toe movements bilaterally. The catheter was removed immediately and found to be intact. Two hours after termination of the procedure, results were available from the laboratory and they revealed: Catheter fluid: glucose 4.94 mmol litre"1, protein 0 Blood: glucose 8.44 mmol litre" 1 3% chloroprocaine: glucose 0.39 mmol litre"1, protein 0 These results suggest that the catheter had migrated into the dural canal while the patient was supine and immobile, even though such episodes may be "so infrequent" (Bonica, 1967). Thus it would appear that the use of a test-dose of local anaesthetic in continuous extradural analgesia is worth while.
