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BRONCHOPLEURAL FISTULA MANAGEMENT DURING ANAESTHESIA
532
BRITISH JOURNAL OF ANAESTHESIA
D. H. G. KEUSKAMP
A mslerdam A copy of the above letter was sent to Dr. Dobkin, who replied as follows. Sir,—In reply to Dr. Keuskamp's letter, I have no brief with the results he claims in his comparison of the neuroleptanalgesic mixture (phentanyl with dehydrobenzperidol) with thialbarbitone nitrous oxide. I would think it was unreasonable to be critical of our results when his comparison did not involve the same experimental conditions, particularly when his study involved patients who were undergoing cardiac surgery. As to the specific points he raised: the blood pressure and body temperature changes we observed were similar to those seen in human volunteers who were not hyperventilated. The changes in serum potassium were greater than those seen in man, but the direction of change was the same. These changes cannot be attributed then to hyperventilation alone (Dobkin, Israel and Byles, 1964). The changes in plasma bicarbonate were insignificant in all of our experiments, but since an issue is raised with regard to this determination, I should point out that in several hundred estimations, I have found that control blood samples in fasting dogs frequently reveal a plasma bicarbonate of 12 to 16 m.mol/I. Whether this is unphysiological or not, I am not prepared to say. The dogs seemed to be quite healthy in spite of this. If Dr. Keuskamp will examine our data more carefully, he will note that we observed an over-all loss in the plasma bicarbonate of 2.1 m.mol/1. in 1 hour (14.3 to 12.2) which is hardly different to the average loss of 1.8 m.mol/1. which he himself reports. The fall in plasma bicarbonate with the thiopentone-
methotrimeprazine mixture, on the other hand, was 0.4 m.mol/1. I should point out also that I am not accustomed to using "crude hyperventilation" as he puts it. The animals were ventilated and the ventilation was checked with precision instruments. They were given 400 ml/kg/nun ventilation throughout all of the experiments. With this rate of ventilation, the mean pH and Pco, of the control arterial samples were 7.4 and 25 mm Hg and after 70 minutes of anaesthesia 7.39 and 23 mm Hg, respectively, in the dogs given neuroleptanalgesia. In the experiments where thiopentone and methotrimeprazine was given, the corresponding control values were pH 7.40, PcOj 25 mm Hg and at the end of 70 minutes of anaesthesia 7.41 and 25 mm Hg. How much less crude can one get? I admit that performing comparative experiments of anaesthetics in dogs is at best artificial, but I wish to assure Dr. Keuskamp that I too recognize the importance of keeping the complex equilibrium in the body as near as possible to the normal physiological level when the effect of an anaesthetic procedure has to be investigated, and I believe that if he re-reads our paper he will be amazed at how well our anaesthetic technique did in fact maintain conditions as he would like. I do not think that it is logical to say blindly one anaesthetic is far superior to another unless valid objective data can be presented to prove the point. I look forward to seeing such supportive data published by Dr. Keuskamp. AIXEN B. DOBKIN
New York
REFERENCE
Dobkin, A. B., Israel, J. S., and Byles, P. H. (1964). Innovan-N,O anaesthesia in normal men: effect on respiration, circulatory dynamics, liver function, metabolic functions, acid-base balance, and psychic responses. Canad. Anaesth. Soc. J., 11, 41. BRONCHOPLEURAL FISTULA MANAGEMENT DURING ANAESTHESIA
Sir,—I have read with interest the paper "Bronchopleural fistula management during anaesthesia" by Drs. Khurana and Snarma (Brit. J. Anaesth. (1964), 36, 302). I feel that this calls for comment lest anaesthetists unfamiliar with thoracic anaesthesia and those in training should regard the anaesthetic technique advocated by these authors as the method of choice in this very dangerous condition. I believe that this technique is contraindicated for the following reasons. The opening sentence of their discussion states: "The two main hazards of anaesthesia in patients with bronchopleural fistula are air leak and spillover and, to avoid these, either occlusion or exclusion methods are invariably advocated." Of these, spillover is the main hazard, and may cause immediate respiratory obstruction during operation or may lead to postoperative pneumonitis and pulmonary suppuration, as these authors point out. To avoid these hazards, "fluid was evacua'.ed from the chest cavity as far as possible before operation", and "the trachea was intubated under general anaesthesia in the head-up position in order to keep the fistula above the level of fluid, and this position was maintained throughout the operation". Aspiration preoperatively cannot guarantee a complete absence of fluid in the chest cavity; this is analogous to the situation following gastric aspiration in cases of intes-
Downloaded from http://bja.oxfordjournals.org/ at Harvard University on July 14, 2015
We had the opportunity of comparing the same neuroleptanalgesic combination with a thialbarbitonenitrous oxide-oxygen sequence in over 75 cases of cardiac surgery. The doses administered were approximately the same as used by Dr. Dobkin (methotrimeprazine, however, was not used). However, the arterial Pco, was painstakingly kept at a level of 40 ±5 mm Hg, continuously controlling the expiratory carbon dioxide percentage by infrared analyzer, and verifying this by samples of arterial blood. In this provisional investigation the most striking facts were: (1) A practically unaltered blood pressure using neuroleptanalgesia. An average drop of 34 mm Hg in blood pressure using thialbarbitone. (2) An average loss of 1.8 m.mol/1. plasma bicarbonate per hour in the neuroleptanalgesic group. A loss of 3.4 m.mol/1. plasma bicarbonate per hour in the thialbarbitone group. This loss of plasma bicarbonate represents the difference in standard bicarbonate between samples drawn directly after induction of anaesthesia and just before the onset of extracorporeal circulation or cardiac arrest, an average of 4 hours elapsing between these estimations. A correct appreciation will be possible after investigating more cases and precise data will be published later. These remarks are made to emphasize the importance of keeping the complex metabolic equilibrium in the body as near as possible to the normal physiological level, when the effect of an anaesthetic procedure has to be investigated.
CORRESPONDENCE
533
J. G. FRANCIS
London
pain threshold, as measured by the tibial pressure technique, in two of the subjects to the same degree as that produced by white sound. The third subject showed no rise in pain threshold doing this exercise nor did he with white sound. We then tried to sec whether we could add the effects of white sound on to the effects produced by distraction. We produced white sound by the method described by Moore, McClurc Browne and Hill, and were unable to detect any further effect by the white sound over and above that shown by distraction. It would seem that their experiments, despite the elegant statistical treatment of their results, would be most unlikely to show any analgesic effects from white sound. Moor, McClure Browne and Hill also say that the intensity of sound from the headphones was measured with a standard sound level meter made by Dawc Instruments. We should be interested to know what coupler was used here between the earphones and the microphone of the sound level meter—the coupler most usually used being, of course, a standard artificial ear. Messrs Dawe Instruments Ltd. inform us that proper coupling between headphones and their standard sound level meter is impossible. The whole question of the production of white sound and the measurement of its intensity has been gone into in some detail by Hesse (1962), reference to which article was made by Moore, McClure Browne and Hill. In the article by Hesse is also shown the response curve of a pair of S. G. Brown super "K" headphones, as presented by the manufacturers, which does not agree with that given by Moore, McClurc Browne and Hill. It is not the purpose of this letter to suggest that white sound is a useful means of providing analgesia but to suggest that our knowledge of white sound has not been enlarged by the article by Moore and his colleagues. JOHN CLUTTON-BROCK
Bristol REFERENCES EFFECT OF WHITE SOUND ON PAIN THRESHOLD
Sir,—-I was interested in the article bv Moore. McClurc Browne and Hill (Brit. J. Anaesth. 0964), 36, 268) on the effect of white sound on the pain threshold. While understanding their wish to use the ischaemic Dain technique described by Hewer and Keele (1948) there would appear to be a very serious objection to the use of this techniaue for investigating the effects of white sound. As mentioned in this article we (CluttonBrock, 1962), using the tibial pressure techniaue, were able to show that white sound of reasonable intensities produced an elevation of the pain threshold very similar to that produced bv distraction. The difference between white sound and distraction presumably is that the effect of white sound does not depend on a voluntary effort on the part of the subiect. With the ifchaemic nain technique the subject has to do a certain amount of work in a given time and it seemed that the concentration reauired to do this properly might well act as a form of distraction. We therefore investigated the effect on the Dain threshold as measured bv the tibial pressure technique, of squeezing the bulb of a manometer in time with a metronome at 60 beats Der minute with sufficient force to measure 150 mm He on a manometer, this being the technique used by Moore, McClure Browne and Hill. This was done on three subjects. The distraction produced a rise in the
Clutton-Brock. J. (1962). Analsesia produced by white sound. Anaesthesia, 17, 87. Hesse. G. E. (1962). Observations on the production of white sound. World Med. Electron.. 1, 55. Hewer. A. J. H., and Keele, C. A. (1948). A method of testing analgesics in man. Lancet, 2. 6F3 Moore. W. M. O.. Browne, J. C. McClure, and Hill. I. D. (1964) Effect of white sound on pain threshold. Brit. J. Anaeslh., 36, 268. RESPIRATORY OBSTRUCTION DUE TO IMPACTION OF THE EPIGLOTTIS TN AN ADULT
Sir,—Since publication of the case report of respiratorv obstruction from impaction of the epielottis (Brit. J. Anaeslh. (1964), 36, 314), Dr. H. J. V. Morton has kindly drawn my attention to two earlier papers on this subject. Pokrzywnicki (1953) reported a patient anaestized with thiopentone, nitrous oxide and oxygen with ether. At second plane of the third stage, prior to intubation, obstruction occurred. Careful larvngoscopv revealed the epielottis being alternately sucked in and blown out of the larvngeal aditus with respiration. This was demonstrated to those present. Caiger and Sichel (1954) describe laryngeal obstruction from this cause in throat surgery. The precipitating factors they regard as being the hyperextension of the head, and
Downloaded from http://bja.oxfordjournals.org/ at Harvard University on July 14, 2015
tinal obstruction. Furthermore, there can be no guarantee that the level of residual fluid will remain below the level of the fistula, even though a head-up position is maintained, when the patient is placed in the lateral position for surgery. These authors state that, except in patients with a small fistula, "the need to aspirate caused frequent interruptions in the course of anaesthesia". In two of their patients gross spillover of pleural fluid into the lung did occur, and in one the operation had to be stopped as the patient's condition deteriorated. This is an incidence of 2 in 22 cases (9 per cent) and in view of the potentially lethal consequences of such a complication, entirely unacceptable. That no more serious sequelae occurred was indeed fortunate. As stated by the authors, the general condition of most patients was poor—such patients are more susceotible to the effects of aspiration of infected pleural fluid. T have witnessed fluid flooding out of an endotracheal tube (a sight never to be forgotten) in a patient with a bronchopleural fistula as he was turned into the lateral position on the operating table; this was accompanied by considerable aspiration and cardiac arrest Even when using blocking techniques such as advocated by Dennison and Lester (Brit. J. Anaesth. (1%1), 33, 655) and Dr. Glennie Smith and myself (Brit. J. Anaeslh. (1962), 34, 817) one never feels entirely free from these hazards until the operation has been safely completed; one at least has the satisfaction of knowing that all reasonable precautions have been taken and that the patient has not been subjected to unnecessary risks. I would contend that the results of the series reported by Drs. Khurana and Sharma, rather than showing that blocking techniques are unnecessary, strongly support the case for their adoption.
BRITISH JOURNAL OF ANAESTHESIA
D. H. G. KEUSKAMP
A mslerdam A copy of the above letter was sent to Dr. Dobkin, who replied as follows. Sir,—In reply to Dr. Keuskamp's letter, I have no brief with the results he claims in his comparison of the neuroleptanalgesic mixture (phentanyl with dehydrobenzperidol) with thialbarbitone nitrous oxide. I would think it was unreasonable to be critical of our results when his comparison did not involve the same experimental conditions, particularly when his study involved patients who were undergoing cardiac surgery. As to the specific points he raised: the blood pressure and body temperature changes we observed were similar to those seen in human volunteers who were not hyperventilated. The changes in serum potassium were greater than those seen in man, but the direction of change was the same. These changes cannot be attributed then to hyperventilation alone (Dobkin, Israel and Byles, 1964). The changes in plasma bicarbonate were insignificant in all of our experiments, but since an issue is raised with regard to this determination, I should point out that in several hundred estimations, I have found that control blood samples in fasting dogs frequently reveal a plasma bicarbonate of 12 to 16 m.mol/I. Whether this is unphysiological or not, I am not prepared to say. The dogs seemed to be quite healthy in spite of this. If Dr. Keuskamp will examine our data more carefully, he will note that we observed an over-all loss in the plasma bicarbonate of 2.1 m.mol/1. in 1 hour (14.3 to 12.2) which is hardly different to the average loss of 1.8 m.mol/1. which he himself reports. The fall in plasma bicarbonate with the thiopentone-
methotrimeprazine mixture, on the other hand, was 0.4 m.mol/1. I should point out also that I am not accustomed to using "crude hyperventilation" as he puts it. The animals were ventilated and the ventilation was checked with precision instruments. They were given 400 ml/kg/nun ventilation throughout all of the experiments. With this rate of ventilation, the mean pH and Pco, of the control arterial samples were 7.4 and 25 mm Hg and after 70 minutes of anaesthesia 7.39 and 23 mm Hg, respectively, in the dogs given neuroleptanalgesia. In the experiments where thiopentone and methotrimeprazine was given, the corresponding control values were pH 7.40, PcOj 25 mm Hg and at the end of 70 minutes of anaesthesia 7.41 and 25 mm Hg. How much less crude can one get? I admit that performing comparative experiments of anaesthetics in dogs is at best artificial, but I wish to assure Dr. Keuskamp that I too recognize the importance of keeping the complex equilibrium in the body as near as possible to the normal physiological level when the effect of an anaesthetic procedure has to be investigated, and I believe that if he re-reads our paper he will be amazed at how well our anaesthetic technique did in fact maintain conditions as he would like. I do not think that it is logical to say blindly one anaesthetic is far superior to another unless valid objective data can be presented to prove the point. I look forward to seeing such supportive data published by Dr. Keuskamp. AIXEN B. DOBKIN
New York
REFERENCE
Dobkin, A. B., Israel, J. S., and Byles, P. H. (1964). Innovan-N,O anaesthesia in normal men: effect on respiration, circulatory dynamics, liver function, metabolic functions, acid-base balance, and psychic responses. Canad. Anaesth. Soc. J., 11, 41. BRONCHOPLEURAL FISTULA MANAGEMENT DURING ANAESTHESIA
Sir,—I have read with interest the paper "Bronchopleural fistula management during anaesthesia" by Drs. Khurana and Snarma (Brit. J. Anaesth. (1964), 36, 302). I feel that this calls for comment lest anaesthetists unfamiliar with thoracic anaesthesia and those in training should regard the anaesthetic technique advocated by these authors as the method of choice in this very dangerous condition. I believe that this technique is contraindicated for the following reasons. The opening sentence of their discussion states: "The two main hazards of anaesthesia in patients with bronchopleural fistula are air leak and spillover and, to avoid these, either occlusion or exclusion methods are invariably advocated." Of these, spillover is the main hazard, and may cause immediate respiratory obstruction during operation or may lead to postoperative pneumonitis and pulmonary suppuration, as these authors point out. To avoid these hazards, "fluid was evacua'.ed from the chest cavity as far as possible before operation", and "the trachea was intubated under general anaesthesia in the head-up position in order to keep the fistula above the level of fluid, and this position was maintained throughout the operation". Aspiration preoperatively cannot guarantee a complete absence of fluid in the chest cavity; this is analogous to the situation following gastric aspiration in cases of intes-
Downloaded from http://bja.oxfordjournals.org/ at Harvard University on July 14, 2015
We had the opportunity of comparing the same neuroleptanalgesic combination with a thialbarbitonenitrous oxide-oxygen sequence in over 75 cases of cardiac surgery. The doses administered were approximately the same as used by Dr. Dobkin (methotrimeprazine, however, was not used). However, the arterial Pco, was painstakingly kept at a level of 40 ±5 mm Hg, continuously controlling the expiratory carbon dioxide percentage by infrared analyzer, and verifying this by samples of arterial blood. In this provisional investigation the most striking facts were: (1) A practically unaltered blood pressure using neuroleptanalgesia. An average drop of 34 mm Hg in blood pressure using thialbarbitone. (2) An average loss of 1.8 m.mol/1. plasma bicarbonate per hour in the neuroleptanalgesic group. A loss of 3.4 m.mol/1. plasma bicarbonate per hour in the thialbarbitone group. This loss of plasma bicarbonate represents the difference in standard bicarbonate between samples drawn directly after induction of anaesthesia and just before the onset of extracorporeal circulation or cardiac arrest, an average of 4 hours elapsing between these estimations. A correct appreciation will be possible after investigating more cases and precise data will be published later. These remarks are made to emphasize the importance of keeping the complex metabolic equilibrium in the body as near as possible to the normal physiological level, when the effect of an anaesthetic procedure has to be investigated.
CORRESPONDENCE
533
J. G. FRANCIS
London
pain threshold, as measured by the tibial pressure technique, in two of the subjects to the same degree as that produced by white sound. The third subject showed no rise in pain threshold doing this exercise nor did he with white sound. We then tried to sec whether we could add the effects of white sound on to the effects produced by distraction. We produced white sound by the method described by Moore, McClurc Browne and Hill, and were unable to detect any further effect by the white sound over and above that shown by distraction. It would seem that their experiments, despite the elegant statistical treatment of their results, would be most unlikely to show any analgesic effects from white sound. Moor, McClure Browne and Hill also say that the intensity of sound from the headphones was measured with a standard sound level meter made by Dawc Instruments. We should be interested to know what coupler was used here between the earphones and the microphone of the sound level meter—the coupler most usually used being, of course, a standard artificial ear. Messrs Dawe Instruments Ltd. inform us that proper coupling between headphones and their standard sound level meter is impossible. The whole question of the production of white sound and the measurement of its intensity has been gone into in some detail by Hesse (1962), reference to which article was made by Moore, McClure Browne and Hill. In the article by Hesse is also shown the response curve of a pair of S. G. Brown super "K" headphones, as presented by the manufacturers, which does not agree with that given by Moore, McClurc Browne and Hill. It is not the purpose of this letter to suggest that white sound is a useful means of providing analgesia but to suggest that our knowledge of white sound has not been enlarged by the article by Moore and his colleagues. JOHN CLUTTON-BROCK
Bristol REFERENCES EFFECT OF WHITE SOUND ON PAIN THRESHOLD
Sir,—-I was interested in the article bv Moore. McClurc Browne and Hill (Brit. J. Anaesth. 0964), 36, 268) on the effect of white sound on the pain threshold. While understanding their wish to use the ischaemic Dain technique described by Hewer and Keele (1948) there would appear to be a very serious objection to the use of this techniaue for investigating the effects of white sound. As mentioned in this article we (CluttonBrock, 1962), using the tibial pressure techniaue, were able to show that white sound of reasonable intensities produced an elevation of the pain threshold very similar to that produced bv distraction. The difference between white sound and distraction presumably is that the effect of white sound does not depend on a voluntary effort on the part of the subiect. With the ifchaemic nain technique the subject has to do a certain amount of work in a given time and it seemed that the concentration reauired to do this properly might well act as a form of distraction. We therefore investigated the effect on the Dain threshold as measured bv the tibial pressure technique, of squeezing the bulb of a manometer in time with a metronome at 60 beats Der minute with sufficient force to measure 150 mm He on a manometer, this being the technique used by Moore, McClure Browne and Hill. This was done on three subjects. The distraction produced a rise in the
Clutton-Brock. J. (1962). Analsesia produced by white sound. Anaesthesia, 17, 87. Hesse. G. E. (1962). Observations on the production of white sound. World Med. Electron.. 1, 55. Hewer. A. J. H., and Keele, C. A. (1948). A method of testing analgesics in man. Lancet, 2. 6F3 Moore. W. M. O.. Browne, J. C. McClure, and Hill. I. D. (1964) Effect of white sound on pain threshold. Brit. J. Anaeslh., 36, 268. RESPIRATORY OBSTRUCTION DUE TO IMPACTION OF THE EPIGLOTTIS TN AN ADULT
Sir,—Since publication of the case report of respiratorv obstruction from impaction of the epielottis (Brit. J. Anaeslh. (1964), 36, 314), Dr. H. J. V. Morton has kindly drawn my attention to two earlier papers on this subject. Pokrzywnicki (1953) reported a patient anaestized with thiopentone, nitrous oxide and oxygen with ether. At second plane of the third stage, prior to intubation, obstruction occurred. Careful larvngoscopv revealed the epielottis being alternately sucked in and blown out of the larvngeal aditus with respiration. This was demonstrated to those present. Caiger and Sichel (1954) describe laryngeal obstruction from this cause in throat surgery. The precipitating factors they regard as being the hyperextension of the head, and
Downloaded from http://bja.oxfordjournals.org/ at Harvard University on July 14, 2015
tinal obstruction. Furthermore, there can be no guarantee that the level of residual fluid will remain below the level of the fistula, even though a head-up position is maintained, when the patient is placed in the lateral position for surgery. These authors state that, except in patients with a small fistula, "the need to aspirate caused frequent interruptions in the course of anaesthesia". In two of their patients gross spillover of pleural fluid into the lung did occur, and in one the operation had to be stopped as the patient's condition deteriorated. This is an incidence of 2 in 22 cases (9 per cent) and in view of the potentially lethal consequences of such a complication, entirely unacceptable. That no more serious sequelae occurred was indeed fortunate. As stated by the authors, the general condition of most patients was poor—such patients are more susceotible to the effects of aspiration of infected pleural fluid. T have witnessed fluid flooding out of an endotracheal tube (a sight never to be forgotten) in a patient with a bronchopleural fistula as he was turned into the lateral position on the operating table; this was accompanied by considerable aspiration and cardiac arrest Even when using blocking techniques such as advocated by Dennison and Lester (Brit. J. Anaesth. (1%1), 33, 655) and Dr. Glennie Smith and myself (Brit. J. Anaeslh. (1962), 34, 817) one never feels entirely free from these hazards until the operation has been safely completed; one at least has the satisfaction of knowing that all reasonable precautions have been taken and that the patient has not been subjected to unnecessary risks. I would contend that the results of the series reported by Drs. Khurana and Sharma, rather than showing that blocking techniques are unnecessary, strongly support the case for their adoption.