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EVALUATION OF A RESPIROMETER FOR NEONATES
Brit. J. Anaesth. (1968), 40, 61
EVALUATION OF A RESPIROMETER FOR NEONATES BY
F. C
D. WILKES, J. B. OWEN-THOMAS, P. R. SWYER AND A. W. CONN
There is a need for a clinically applicable instrument for the measurement of minute volume in the newborn. A commonly used adult respirometer (Wright, 1955, 1958) has errors of measurement at rates of breathing above 40 per minute and at peak flows below 3.8 l./min (Byles, 1960; Hall and Reeser, 1962; Nunn and Ezi-Ashi, 1962) and is therefore unsuitable for neonatal measurements. Plethysmography (Cross, 1949; Du Bois et al., 1956; Karlberg et al., 1960) and pneumotachography (OwenThomas, 1967; Swyer, Reiman and Wright, 1960) require relatively complex equipment, accurate calibration procedures and personnel trained in their use. One of us (F.C.D.W.) has redesigned the Wright respirometer in such a way as to make it suitable for the measurement of the lower respiratory volumes of neonates. We report an evaluation of its performance in a closed circuit system using a Krogh spirometer as modified by Adamsons (1959) and Levison, Delivoria-Papadopoulos and Swyer (1965) (fig. 1). The purpose of this study was (1) to check the dynamic calibration of the respirometer against Reprint requests to: A.W.C., Department of Anaesthesia, The Hospital for Sick Children, Toronto, Ontario, Canada.
FIG. 1 Closed circuit system modified for the evaluation of the infant respirometer. When the gas line is clamped at A the Krogh spirometer only is functional. When clamp is applied at B the respirometer and spirometer are in series and simultaneous readings can be made. Gas was recirculated at 9 L/min.
a previously calibrated Krogh spirometer and (2) to evaluate any change in minute volume resulting from the series interposition of the respirometer in the Krogh circuit, due to the added resistance to breathing. From the information gained in (1) and (2) above, a prediction of Krogh spirometric minute
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
SUMMARY
The adult (Wright) respirometer has been redesigned for neonates. A calibrated Krogh spirometer has been used to check the accuracy and a regression relationship derived over a range of minute volumes 0.4-2.8 l./min. The added resistance of 29 cm H , O / l./sec lowered minute volume according to a second regression line which was also experimentally derived. Combining the two regressions allows true minute volume to be predicted from the respirometer reading. This respirometer is potentially useful in ventilator and anaesthetic circuits.
62
BRITISH JOURNAL OF ANAESTHESIA
volume could then be obtained from the respirometer readings, hence yielding an estimate of minute volume uninfluenced by the respirometer resistance. METHODS
An electrical analogue of tidal volume was recorded after amplifying the signal produced by displacement of an angular transducer (Metrisite Brush Instruments, Cleveland, Ohio, USA) attached to the spirometer. Expired tidal volumes were measured and totalled over 1 minute. The respirometer was sited in such a way that it could be included or excluded from the circuit by crossdamping the tubes at A or B (fig. 1). Ten readings of spirometer and respirometer minute volumes were simultaneously recorded (damp at B) and ten spirometer readings with the respirometer exduded from the circuit (clamp at A) for each infant. Observations were randomized, measuring minute volumes with the respirometer alternatively in and out of the circuit for each patient. In order to ensure comparable conditions only uninterrupted records over 20 minutes were used. The drop in pressure across the respirometer in response to steady flow of up to 300 ml/sec was measured and the resistance of the instrument was calculated.
The calibration of the respirometer, as indicated by simultaneously recorded Krogh spirometer volumes, is given by the regression equation Krogh=0.054+ 0.935 x respirometer (fig. 2), over the range of 0.4—2.6 l./min.
i .20
i
i .60
i
i 1 00
i
I 140
i
r
T
180
X=Respirometer (L/min ) FIG. 2
i i 2 20
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Sixteen infants with normal respiratory function were studied, ranging in age from 5 to 28 days and ranging in weight from 1.5 to 32 kg. All were tested 30 minutes following feeding. No special effort was made to study the infants under resting conditions as the object was only to evaluate the performance of the instrument. The infant was swaddled, and a ring of warm, watersoluble jelly, applied to the face and pneumatic rim of the face mask. The face mask contained a baffle which deflected circulating gas across the face in order to avoid rebreathing. A gas mixture containing 60 to 80 per cent oxygen was recirculated at a rate of 9 l./min with a carbon dioxide absorber in the circuit (fig. 1). The face mask was then connected to the dosed circuit as shown (fig. 1). Calibration of the spirometer was by a calibrated glass syringe. The dynamic response of the system was linear up to 100 cycles/min to a ± 5 per cent error.
RESULTS
2.60
Regression of the respirometer minute volume on Krogh spirometer minute volumes, simultaneously recorded with the two instruments in series (clamp in position B—see fig. 1). Each point represents the mean of ten observations. The 95 per cent confidence limits of the line of regression are shown.
There was a lowering in minute volume consequent on the flow resistance of the respirometer. This accords with the work of Milic-Emili and Tyler (1963) in adults who showed that minute volume decreases as non-elastic resistance to breathing increases. The flow resistance of the respirometer was 29 cm HjO/l./sec, a value which is comparable to the non-elastic flow resistance of the spontaneously breathing newborn infant (Cook et al., 1957; Swyer, Reiman and Wright, 1960), and the regression equation describing this relationship is Krogh=-0.137 + 1.245xKrogh (loaded with respirometer) (fig. 3). The regression equations allow prediction of (Krogh spirometer) minute volume from the respirometer reading obtained from any given
EVALUATION OF A RESPIROMETER FOR NEONATES patient in the following way: In figure 2 assume (1) Respirometer minute volume reading (2) Read Krogh minute volume
= 1.51. = 1.461.
On figure 3 (1) Read true Rrogh minute volume (series loaded) on abscissa =1.461. (2) Find true Krogh (unloaded) minute volume on the ordinate =1.661.
Recalibration of the respirometer dial according to the predictions in the two regression equations, will therefore enable true minute volume to be measured. ACKNOWLEDGEMENTS
We wish to thank Professor W. H. Le Riche and Mr. Glen Tones, School of Hygiene, University of Toronto, for advising on and carrying out the statistical evaluation of the study. We also wish to thank Mrs. M. MacDonald, R.N., for invaluable assistance during the Hiniml observations, Mr. D. Mclntosh for technical assistance with the apparatus, and Mrs. C. Robinson for secretarial help. PEFERENCES
20
.60
1.00
140 180 2.20 2.60 (l./min ) X=KROGH (in leriei with rojpiromeler) FIG. 3
Regression of Krogh spirometer minute volumes with the respirometer in series circuit (clamp on position B in fig. 1) on Krogh spirometer minute volumes with respirometer excluded (clamp on position A, fig. 1). Each point represents the mean of ten observations. The 95 per cent confidence limits on the line of regression are shown.
It is concluded that the respirometer is potentially useful in ventilator and anaesthetic circuits for newborn infants. Providing significant rebreathing can be avoided, spontaneous respiration can be predictably measured.
Adamsons, L. (1959). Breathing and the thermal environment in young rabbits. J. Physiol. (Lend.), 149, 144. Byles, P. H. (1960). Observations on some continuously acting spirometers. Brit. J. Anaesth., 32, 470. Cook, C. D., Sutherland, J. M., Segal, S., Cherry, R. B., Mead, J., Mcllroy, M. B., and Smith, C. A. (1957). Studies of respiratory physiology in the newborn infant. I l l : Measurements of mechanics of respiration. J. rlin. Invest. 36, 440. Cross, K. W. (1949). The respiratory rate and ventilation in the newborn baby. J. Physiol. (Lond.), 109, 459. Du Bois, A. B., Botelho, S. Y., Bedell, G. N., Marshall, R., and Comroe, J. H. (1956). A new method for measuring airway resistance in man using a body plethysmograph. J. din. Invest.. 35, 327. Hall, K. D., and Reeser, F. H. (1962). Calibration of Wright spirometer. Anesthesiology, 23, 126. Karlberg, P., Cherry, R. B., Escardo, F., and Koch, G. (i960). Respiratory studies in newborns. I : Apparatus and methods for studies of the pulmonary ventilation and the mechanics of breathing: principles of analysis in mechanics of breathing. Acta paediat. (Uppsala), 49, 345. Levison, H., Delivoria-Papadopoulos, M., and Swyer, P. R. (1965). Variations in oxygen consumption in the infant with hypoxaemia due to cardiopulmonary disease. Acta paediat. (Uppsala), 54, 369. Milic-Emili, J., and Tyler, J. M. (1963). Relationship between PAOO, and respiratory work during external resistance breathing in man. Ann. N.Y. Acad. Set., 109, 908. Nunn, J. F., and Ezi-Ashi, T. I. (1962). The accuracy of the respirometer and ventigrator. Brit. J. Anaesth., 34, 422. Owen-Thomas, J. B. (1967). A pneumotachograph evaluated for controlled ventilation in childhood. Canad. Anaesth. Soc. J., 14, 220. Swyer, P. R., Reiman, R. C , and Wright, J. J. (1960). Ventilation and ventilatory mechanics in the newborn. J. Pediat., 56, 612. Wright, B. M. (1955). A respiratory anemometer 7 Physiol. (Lond.), 127, 25. (1958). Symposiian on Pulmonary Ventilation. Published for Brit. 7. Anaesth. (eds. Harbord, R. P., and Woolmer, R.), p. 91.
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Hence when the respirometer minute volume reading is 1.50 1. then true minute volume would be 1.66 1.
63
BRITISH JOURNAL OF ANAESTHESIA
64 EVALUATION DTTN RESPIROMETRE POUR NOUVEAU-NES
AUSWERTUNG DER EICHDATEN EINES NEUGEBORENEN-RESPIROMETERS
SOMMADtE
Das Erwachsenen-Respirometer nach Wright ist fur die Verhaitnisse von Neugeborenen umkonstruiert worden. Zur Genauigkeitskontrolle wurde ein geeichtes Krogh'sches Spirometer verwendet, wobei cine Regressionsfunktion fiir den Minutenyolumenbereich 0,42,8 l./min erarbeitet wurde. Bei einem zusStzlichen Widerstand von 29 cm H,O/l./sec wurden die Minutenvolumina entsprechend einer ebenfalls experimentell abgeleiteten weiteren Regressionslinie emiedrigt. Bei Kombination der beiden Regressionslinien kann das wahre Minutenvolumen aus dem am Respirometer abgelesenen Meflwert erschlossen werden. Dieses Respirometer hat vorteilhafte Anwendungsmoglichkeiten in Stromungskreisen, die bei Ventilations- und Anasthesieaufgaben benutzt werden.
ZUSAMMENFASSUNG
BOOK REVIEW Internationale Konfertnz fur Traumatologie (Budapest, October 19-21, 1961). Published by Akademiai Kiadd, Budapest. Pp. 328. The proceedings of the International Conference on Traumatology, held in Budapest in October 1961, have now become available in German. The first 22 communications, about a quarter of the proceedings, deal with resuscitation and anaesthesia. In the introductory lecture W. A. Negowski, of Moscow, considers resuscitation to be a new branch of medicine, naming it reanimatology, whose task begins when life has ceased. In cases of slow death or irreversible shock he recommends, on the basis of 25 years' clinical and experimental research, intra-arterial transfusion under pressure, together with artificial respiration with 100 per cent oxygen, defibrillation and open cardiac massage. During the early post-massage period intravenous infusion of sodium bicarbonate and exchange transfusion have been of decisive aid towards recovery. Negowski's publications seem to exert considerable influence, and intra-arterial transfusion is used by a number of authors, often combined with intravenous transfusion and with hibernation. A selection of interesting observations and practical hints may indicate the wide range covered by the papers. Cardiac arrest in dogs was achieved through tamponade produced by intrapericardial injection of normal saline, thus avoiding chemical or electrical damage to the myocardium. Postmortem examination of the hearts of 25 patients treated by cardiac massage led to the conclusion that the pathological findings were not related to the duration of the massage. Szekely and Heid, of Budapest, describe the successful treatment of 26 patients suffering from thoracic injuries in whom oxygen saturation of the blood remained low despite mechanical ventilation and ample oxygenation. They transfused oxygenated blood, obtained by adding 1 ml of freshly prepared 3 per cent H,O, solution to 100 ml stored blood. Allowing at least 30 minutes for the mixture to reach equilibrium, they infused daily 200-1200 ml for up to 4 days. A comprehensive paper on anaesthesia in the early stages after injury mentions two short-acting relaxants,
MY .301 and Relaxil-G, which are said to be without influence on respiration. Various forms of shock and their treatment are then described. Collapse with peripheral vasoconstriction, normal or slightly raised blood pressure but low pulse pressure, accompanied by excitement, is managed by careful administration of the lytic cocktail, while shock characterized by dilatation of the blood vessels is treated with massive transfusion and, simultaneously, with noradrenaline, aiming at keeping the blood pressure just under 100 mg Hg. If such stabilization cannot be achieved hypothermia is applied, a method which seems to be widely used in Eastern Europe. Views on preparation of the injured for operation and on indications for intubation, mechanical ventilation and tracheotomy are similar to those held by anaesthetists in English-speaking countries. Several authors advise hydroxydione anaesthesia for orthopaedic operations in the elderly, as it is thought to cause the least stress. It failed to art, however, in a patient under cortisone treatment. As adrenal function is often depressed in geriatric patients it should be tested by eosinophil counts before and after intravenous injection of 50 ml 40 per cent dextrose. If the count is not reduced by at least 50 per cent, administration of extract of whole adrenal is recommended prior to anaesthesia. Experience with phencyclidine is similar to British results; it is satisfactory in orthopaedic operations on patients over 60 but in younger people excitement and hallucinations are caused. One author describes successful reduction of many dislocations and fractures of the upper extremity by slow traction followed by pressure, without any anaesthetic and without mentioning the use of analgesics! Although literature is quoted, a bibliography has not been provided, perhaps on the assumption that users of thi
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Lc respirometre (Wright) pour adultes a etc transforme pour les nouveau-nes. Un respirometre calibre de Krogh a etc employ* pour verifier l'exactitude et une relation de regression a etc derivee sur une s^rie de volumes-minute de 0,4 a 2,8 l./min. La resistance supplementaire de 29 cm H,O/l./sec. reduisit le volume-minute suivant une seconde ligne de regression, qui a egalement eti derivee expe^rimentalement. Combiner les deux regressions pennet de predire au depart de la lecture du respirometre, le vrai volumeminute. Celui-ci semble pouvoir etre utile dans des circuits de ventilation et d'anesthesie.
EVALUATION OF A RESPIROMETER FOR NEONATES BY
F. C
D. WILKES, J. B. OWEN-THOMAS, P. R. SWYER AND A. W. CONN
There is a need for a clinically applicable instrument for the measurement of minute volume in the newborn. A commonly used adult respirometer (Wright, 1955, 1958) has errors of measurement at rates of breathing above 40 per minute and at peak flows below 3.8 l./min (Byles, 1960; Hall and Reeser, 1962; Nunn and Ezi-Ashi, 1962) and is therefore unsuitable for neonatal measurements. Plethysmography (Cross, 1949; Du Bois et al., 1956; Karlberg et al., 1960) and pneumotachography (OwenThomas, 1967; Swyer, Reiman and Wright, 1960) require relatively complex equipment, accurate calibration procedures and personnel trained in their use. One of us (F.C.D.W.) has redesigned the Wright respirometer in such a way as to make it suitable for the measurement of the lower respiratory volumes of neonates. We report an evaluation of its performance in a closed circuit system using a Krogh spirometer as modified by Adamsons (1959) and Levison, Delivoria-Papadopoulos and Swyer (1965) (fig. 1). The purpose of this study was (1) to check the dynamic calibration of the respirometer against Reprint requests to: A.W.C., Department of Anaesthesia, The Hospital for Sick Children, Toronto, Ontario, Canada.
FIG. 1 Closed circuit system modified for the evaluation of the infant respirometer. When the gas line is clamped at A the Krogh spirometer only is functional. When clamp is applied at B the respirometer and spirometer are in series and simultaneous readings can be made. Gas was recirculated at 9 L/min.
a previously calibrated Krogh spirometer and (2) to evaluate any change in minute volume resulting from the series interposition of the respirometer in the Krogh circuit, due to the added resistance to breathing. From the information gained in (1) and (2) above, a prediction of Krogh spirometric minute
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
SUMMARY
The adult (Wright) respirometer has been redesigned for neonates. A calibrated Krogh spirometer has been used to check the accuracy and a regression relationship derived over a range of minute volumes 0.4-2.8 l./min. The added resistance of 29 cm H , O / l./sec lowered minute volume according to a second regression line which was also experimentally derived. Combining the two regressions allows true minute volume to be predicted from the respirometer reading. This respirometer is potentially useful in ventilator and anaesthetic circuits.
62
BRITISH JOURNAL OF ANAESTHESIA
volume could then be obtained from the respirometer readings, hence yielding an estimate of minute volume uninfluenced by the respirometer resistance. METHODS
An electrical analogue of tidal volume was recorded after amplifying the signal produced by displacement of an angular transducer (Metrisite Brush Instruments, Cleveland, Ohio, USA) attached to the spirometer. Expired tidal volumes were measured and totalled over 1 minute. The respirometer was sited in such a way that it could be included or excluded from the circuit by crossdamping the tubes at A or B (fig. 1). Ten readings of spirometer and respirometer minute volumes were simultaneously recorded (damp at B) and ten spirometer readings with the respirometer exduded from the circuit (clamp at A) for each infant. Observations were randomized, measuring minute volumes with the respirometer alternatively in and out of the circuit for each patient. In order to ensure comparable conditions only uninterrupted records over 20 minutes were used. The drop in pressure across the respirometer in response to steady flow of up to 300 ml/sec was measured and the resistance of the instrument was calculated.
The calibration of the respirometer, as indicated by simultaneously recorded Krogh spirometer volumes, is given by the regression equation Krogh=0.054+ 0.935 x respirometer (fig. 2), over the range of 0.4—2.6 l./min.
i .20
i
i .60
i
i 1 00
i
I 140
i
r
T
180
X=Respirometer (L/min ) FIG. 2
i i 2 20
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Sixteen infants with normal respiratory function were studied, ranging in age from 5 to 28 days and ranging in weight from 1.5 to 32 kg. All were tested 30 minutes following feeding. No special effort was made to study the infants under resting conditions as the object was only to evaluate the performance of the instrument. The infant was swaddled, and a ring of warm, watersoluble jelly, applied to the face and pneumatic rim of the face mask. The face mask contained a baffle which deflected circulating gas across the face in order to avoid rebreathing. A gas mixture containing 60 to 80 per cent oxygen was recirculated at a rate of 9 l./min with a carbon dioxide absorber in the circuit (fig. 1). The face mask was then connected to the dosed circuit as shown (fig. 1). Calibration of the spirometer was by a calibrated glass syringe. The dynamic response of the system was linear up to 100 cycles/min to a ± 5 per cent error.
RESULTS
2.60
Regression of the respirometer minute volume on Krogh spirometer minute volumes, simultaneously recorded with the two instruments in series (clamp in position B—see fig. 1). Each point represents the mean of ten observations. The 95 per cent confidence limits of the line of regression are shown.
There was a lowering in minute volume consequent on the flow resistance of the respirometer. This accords with the work of Milic-Emili and Tyler (1963) in adults who showed that minute volume decreases as non-elastic resistance to breathing increases. The flow resistance of the respirometer was 29 cm HjO/l./sec, a value which is comparable to the non-elastic flow resistance of the spontaneously breathing newborn infant (Cook et al., 1957; Swyer, Reiman and Wright, 1960), and the regression equation describing this relationship is Krogh=-0.137 + 1.245xKrogh (loaded with respirometer) (fig. 3). The regression equations allow prediction of (Krogh spirometer) minute volume from the respirometer reading obtained from any given
EVALUATION OF A RESPIROMETER FOR NEONATES patient in the following way: In figure 2 assume (1) Respirometer minute volume reading (2) Read Krogh minute volume
= 1.51. = 1.461.
On figure 3 (1) Read true Rrogh minute volume (series loaded) on abscissa =1.461. (2) Find true Krogh (unloaded) minute volume on the ordinate =1.661.
Recalibration of the respirometer dial according to the predictions in the two regression equations, will therefore enable true minute volume to be measured. ACKNOWLEDGEMENTS
We wish to thank Professor W. H. Le Riche and Mr. Glen Tones, School of Hygiene, University of Toronto, for advising on and carrying out the statistical evaluation of the study. We also wish to thank Mrs. M. MacDonald, R.N., for invaluable assistance during the Hiniml observations, Mr. D. Mclntosh for technical assistance with the apparatus, and Mrs. C. Robinson for secretarial help. PEFERENCES
20
.60
1.00
140 180 2.20 2.60 (l./min ) X=KROGH (in leriei with rojpiromeler) FIG. 3
Regression of Krogh spirometer minute volumes with the respirometer in series circuit (clamp on position B in fig. 1) on Krogh spirometer minute volumes with respirometer excluded (clamp on position A, fig. 1). Each point represents the mean of ten observations. The 95 per cent confidence limits on the line of regression are shown.
It is concluded that the respirometer is potentially useful in ventilator and anaesthetic circuits for newborn infants. Providing significant rebreathing can be avoided, spontaneous respiration can be predictably measured.
Adamsons, L. (1959). Breathing and the thermal environment in young rabbits. J. Physiol. (Lend.), 149, 144. Byles, P. H. (1960). Observations on some continuously acting spirometers. Brit. J. Anaesth., 32, 470. Cook, C. D., Sutherland, J. M., Segal, S., Cherry, R. B., Mead, J., Mcllroy, M. B., and Smith, C. A. (1957). Studies of respiratory physiology in the newborn infant. I l l : Measurements of mechanics of respiration. J. rlin. Invest. 36, 440. Cross, K. W. (1949). The respiratory rate and ventilation in the newborn baby. J. Physiol. (Lond.), 109, 459. Du Bois, A. B., Botelho, S. Y., Bedell, G. N., Marshall, R., and Comroe, J. H. (1956). A new method for measuring airway resistance in man using a body plethysmograph. J. din. Invest.. 35, 327. Hall, K. D., and Reeser, F. H. (1962). Calibration of Wright spirometer. Anesthesiology, 23, 126. Karlberg, P., Cherry, R. B., Escardo, F., and Koch, G. (i960). Respiratory studies in newborns. I : Apparatus and methods for studies of the pulmonary ventilation and the mechanics of breathing: principles of analysis in mechanics of breathing. Acta paediat. (Uppsala), 49, 345. Levison, H., Delivoria-Papadopoulos, M., and Swyer, P. R. (1965). Variations in oxygen consumption in the infant with hypoxaemia due to cardiopulmonary disease. Acta paediat. (Uppsala), 54, 369. Milic-Emili, J., and Tyler, J. M. (1963). Relationship between PAOO, and respiratory work during external resistance breathing in man. Ann. N.Y. Acad. Set., 109, 908. Nunn, J. F., and Ezi-Ashi, T. I. (1962). The accuracy of the respirometer and ventigrator. Brit. J. Anaesth., 34, 422. Owen-Thomas, J. B. (1967). A pneumotachograph evaluated for controlled ventilation in childhood. Canad. Anaesth. Soc. J., 14, 220. Swyer, P. R., Reiman, R. C , and Wright, J. J. (1960). Ventilation and ventilatory mechanics in the newborn. J. Pediat., 56, 612. Wright, B. M. (1955). A respiratory anemometer 7 Physiol. (Lond.), 127, 25. (1958). Symposiian on Pulmonary Ventilation. Published for Brit. 7. Anaesth. (eds. Harbord, R. P., and Woolmer, R.), p. 91.
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Hence when the respirometer minute volume reading is 1.50 1. then true minute volume would be 1.66 1.
63
BRITISH JOURNAL OF ANAESTHESIA
64 EVALUATION DTTN RESPIROMETRE POUR NOUVEAU-NES
AUSWERTUNG DER EICHDATEN EINES NEUGEBORENEN-RESPIROMETERS
SOMMADtE
Das Erwachsenen-Respirometer nach Wright ist fur die Verhaitnisse von Neugeborenen umkonstruiert worden. Zur Genauigkeitskontrolle wurde ein geeichtes Krogh'sches Spirometer verwendet, wobei cine Regressionsfunktion fiir den Minutenyolumenbereich 0,42,8 l./min erarbeitet wurde. Bei einem zusStzlichen Widerstand von 29 cm H,O/l./sec wurden die Minutenvolumina entsprechend einer ebenfalls experimentell abgeleiteten weiteren Regressionslinie emiedrigt. Bei Kombination der beiden Regressionslinien kann das wahre Minutenvolumen aus dem am Respirometer abgelesenen Meflwert erschlossen werden. Dieses Respirometer hat vorteilhafte Anwendungsmoglichkeiten in Stromungskreisen, die bei Ventilations- und Anasthesieaufgaben benutzt werden.
ZUSAMMENFASSUNG
BOOK REVIEW Internationale Konfertnz fur Traumatologie (Budapest, October 19-21, 1961). Published by Akademiai Kiadd, Budapest. Pp. 328. The proceedings of the International Conference on Traumatology, held in Budapest in October 1961, have now become available in German. The first 22 communications, about a quarter of the proceedings, deal with resuscitation and anaesthesia. In the introductory lecture W. A. Negowski, of Moscow, considers resuscitation to be a new branch of medicine, naming it reanimatology, whose task begins when life has ceased. In cases of slow death or irreversible shock he recommends, on the basis of 25 years' clinical and experimental research, intra-arterial transfusion under pressure, together with artificial respiration with 100 per cent oxygen, defibrillation and open cardiac massage. During the early post-massage period intravenous infusion of sodium bicarbonate and exchange transfusion have been of decisive aid towards recovery. Negowski's publications seem to exert considerable influence, and intra-arterial transfusion is used by a number of authors, often combined with intravenous transfusion and with hibernation. A selection of interesting observations and practical hints may indicate the wide range covered by the papers. Cardiac arrest in dogs was achieved through tamponade produced by intrapericardial injection of normal saline, thus avoiding chemical or electrical damage to the myocardium. Postmortem examination of the hearts of 25 patients treated by cardiac massage led to the conclusion that the pathological findings were not related to the duration of the massage. Szekely and Heid, of Budapest, describe the successful treatment of 26 patients suffering from thoracic injuries in whom oxygen saturation of the blood remained low despite mechanical ventilation and ample oxygenation. They transfused oxygenated blood, obtained by adding 1 ml of freshly prepared 3 per cent H,O, solution to 100 ml stored blood. Allowing at least 30 minutes for the mixture to reach equilibrium, they infused daily 200-1200 ml for up to 4 days. A comprehensive paper on anaesthesia in the early stages after injury mentions two short-acting relaxants,
MY .301 and Relaxil-G, which are said to be without influence on respiration. Various forms of shock and their treatment are then described. Collapse with peripheral vasoconstriction, normal or slightly raised blood pressure but low pulse pressure, accompanied by excitement, is managed by careful administration of the lytic cocktail, while shock characterized by dilatation of the blood vessels is treated with massive transfusion and, simultaneously, with noradrenaline, aiming at keeping the blood pressure just under 100 mg Hg. If such stabilization cannot be achieved hypothermia is applied, a method which seems to be widely used in Eastern Europe. Views on preparation of the injured for operation and on indications for intubation, mechanical ventilation and tracheotomy are similar to those held by anaesthetists in English-speaking countries. Several authors advise hydroxydione anaesthesia for orthopaedic operations in the elderly, as it is thought to cause the least stress. It failed to art, however, in a patient under cortisone treatment. As adrenal function is often depressed in geriatric patients it should be tested by eosinophil counts before and after intravenous injection of 50 ml 40 per cent dextrose. If the count is not reduced by at least 50 per cent, administration of extract of whole adrenal is recommended prior to anaesthesia. Experience with phencyclidine is similar to British results; it is satisfactory in orthopaedic operations on patients over 60 but in younger people excitement and hallucinations are caused. One author describes successful reduction of many dislocations and fractures of the upper extremity by slow traction followed by pressure, without any anaesthetic and without mentioning the use of analgesics! Although literature is quoted, a bibliography has not been provided, perhaps on the assumption that users of thi
Downloaded from http://bja.oxfordjournals.org/ at Indiana University Library on July 10, 2015
Lc respirometre (Wright) pour adultes a etc transforme pour les nouveau-nes. Un respirometre calibre de Krogh a etc employ* pour verifier l'exactitude et une relation de regression a etc derivee sur une s^rie de volumes-minute de 0,4 a 2,8 l./min. La resistance supplementaire de 29 cm H,O/l./sec. reduisit le volume-minute suivant une seconde ligne de regression, qui a egalement eti derivee expe^rimentalement. Combiner les deux regressions pennet de predire au depart de la lecture du respirometre, le vrai volumeminute. Celui-ci semble pouvoir etre utile dans des circuits de ventilation et d'anesthesie.