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NASAL INTUBATION
BRITISH JOURNAL OF ANAESTHESIA
420
change in the balloon during such swings is of the order of 0.01 ml distributed over 15 cm of oesophagus. Finally, sir, may we say what a pleasure it is to see the columns of your journal so generously offered for the discussion of a published paper. It is a pity that constructive, well-informed criticism of this kind is not more common. R. MARSHALL J. PARKHOUSE B. R. SIMPSON
Oxford NASAL INTUBATION
Sir,—I find Dr. Vellacott's article, "Nasal intubation: some postnasal obstructions and how they are overcome" (Brit. J. Anaesth., 1962, 34, 115), most interesting. I have had this experience a few times and I am sure many other anaesthetists have also. However, I do remember on one occasion being unable to deliver the tube even with my finger, and got over this problem by passing a Ryle's tube down the endotracheal tube already in place, and picking up the end of the Ryle's tube, now visible in the pharynx, with a Magill's forceps. This put an additional curve on the distal end of the endotracheal tube, which could then be pushed towards the larynx. C. H.
DUNN
Isleworth, Middlesex
REPRINTS
Sir,—A large number of reprints of the paper "Promethazine: its influence on the course of thiopentone and methohexital anaesthesia" (Anaesthesia, 1961, 16, 61) have been sent to anaesthetists in the United States. The authors of this paper wish it to be known that they are not at all responsible for sending these.
Primed in Great Britain by John Sherratt and Son. Park Road. Altrincham
JAMES MOORE JOHN W. DUNDEE
Belfast
Downloaded from http://bja.oxfordjournals.org/ at University of Sussex on August 19, 2015
are based on the patients' subjective feelings or not. Most drugs have more than one action, and there are usually several ways of measuring each. "Duration of action" is thus a meaningless term in any absolute sense. Dr. Bromage has "pinned" his faith on what he calls "objective analgesia"; this is legitimate but there is no justification for regarding the method as inherently better than others. Tachyphylaxis, for example, despite Dr. Bromage's rhetorical question, has often been demonstrated subjectively when intermittent caudal injections are given for obstetrical analgesia. The fact is that in our cases it simply did not occur. We tried concentrations of less than 1 per cent lignocaine but although pain relief was satisfactory at rest a pulling sensation often occurred on movement. Our respiratory studies were not designed to answer any "crucial question" and we took some care to avoid being "led astray". The pre-operative compliance measurements were made one or two days before operation; they should not be compared critically with those made at relatively close intervals of time on the day of operation. Compliance was always measured after vital capacity, so approximately the same number of deep breaths had been taken on each occasion. The significant finding was the small change in compliance with extradural analgesia alone and the large increase after movement and coughing. It is difficult to believe that the movement and coughing caused any appreciable change in the characteristics of the balloon system or of the oesophagus; the position of the oesophageal tube at the nose was unchanged by coughing and on withdrawal of the tube there was no evidence that it had been doubled-up or kinked. The balloon normally contained 1.5 ml of air and this volume was checked before each measurement. The compliance of the oesophageal tube-manometer system was approximately 0.01 ml/cm H 2 O; although a change in oesophageal tone might—but in our cases did not—alter the absolute level of intraoesophageal pressure, it is hard to imagine a change in oesophageal tone which would affect the pressure swings during respiration. The volume
420
change in the balloon during such swings is of the order of 0.01 ml distributed over 15 cm of oesophagus. Finally, sir, may we say what a pleasure it is to see the columns of your journal so generously offered for the discussion of a published paper. It is a pity that constructive, well-informed criticism of this kind is not more common. R. MARSHALL J. PARKHOUSE B. R. SIMPSON
Oxford NASAL INTUBATION
Sir,—I find Dr. Vellacott's article, "Nasal intubation: some postnasal obstructions and how they are overcome" (Brit. J. Anaesth., 1962, 34, 115), most interesting. I have had this experience a few times and I am sure many other anaesthetists have also. However, I do remember on one occasion being unable to deliver the tube even with my finger, and got over this problem by passing a Ryle's tube down the endotracheal tube already in place, and picking up the end of the Ryle's tube, now visible in the pharynx, with a Magill's forceps. This put an additional curve on the distal end of the endotracheal tube, which could then be pushed towards the larynx. C. H.
DUNN
Isleworth, Middlesex
REPRINTS
Sir,—A large number of reprints of the paper "Promethazine: its influence on the course of thiopentone and methohexital anaesthesia" (Anaesthesia, 1961, 16, 61) have been sent to anaesthetists in the United States. The authors of this paper wish it to be known that they are not at all responsible for sending these.
Primed in Great Britain by John Sherratt and Son. Park Road. Altrincham
JAMES MOORE JOHN W. DUNDEE
Belfast
Downloaded from http://bja.oxfordjournals.org/ at University of Sussex on August 19, 2015
are based on the patients' subjective feelings or not. Most drugs have more than one action, and there are usually several ways of measuring each. "Duration of action" is thus a meaningless term in any absolute sense. Dr. Bromage has "pinned" his faith on what he calls "objective analgesia"; this is legitimate but there is no justification for regarding the method as inherently better than others. Tachyphylaxis, for example, despite Dr. Bromage's rhetorical question, has often been demonstrated subjectively when intermittent caudal injections are given for obstetrical analgesia. The fact is that in our cases it simply did not occur. We tried concentrations of less than 1 per cent lignocaine but although pain relief was satisfactory at rest a pulling sensation often occurred on movement. Our respiratory studies were not designed to answer any "crucial question" and we took some care to avoid being "led astray". The pre-operative compliance measurements were made one or two days before operation; they should not be compared critically with those made at relatively close intervals of time on the day of operation. Compliance was always measured after vital capacity, so approximately the same number of deep breaths had been taken on each occasion. The significant finding was the small change in compliance with extradural analgesia alone and the large increase after movement and coughing. It is difficult to believe that the movement and coughing caused any appreciable change in the characteristics of the balloon system or of the oesophagus; the position of the oesophageal tube at the nose was unchanged by coughing and on withdrawal of the tube there was no evidence that it had been doubled-up or kinked. The balloon normally contained 1.5 ml of air and this volume was checked before each measurement. The compliance of the oesophageal tube-manometer system was approximately 0.01 ml/cm H 2 O; although a change in oesophageal tone might—but in our cases did not—alter the absolute level of intraoesophageal pressure, it is hard to imagine a change in oesophageal tone which would affect the pressure swings during respiration. The volume