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THE INCIDENCE OF POSTOPERATIVE ATELECTASIS IN THE DEPENDENT LUNG FOLLOWING THORACOTOMY: THE VALUE OF ADDED NITROGEN
Brit. J. Anaesth. (1970), 42, 340
THE INCIDENCE OF POSTOPERATIVE ATELECTASIS IN THE DEPENDENT LUNG FOLLOWING THORACOTOMY: THE VALUE OF ADDED NITROGEN BY
DOREEN R. G. BROWNE, J. ROCHFORD, U. O'CONNELL AND J. G. JONES SUMMARY
Originally the term "atelectasis" was coined from the Greek words "ateles" meaning imperfect and "ektasis" meaning expansion, by Jorg in 1835, but it has been more recently described by Hamilton (1961) as a condition in which there is collapse of one or more definite anatomical units of the lung. Atelectasis of a lobule, segment, lobe or entire lung may occur and the incidence of this condition after operation has been shown to vary depending on the criteria of measurement. Clinical signs including displacement of the apex beat, tachycardia and fever, changes in the pulmonary function tests, arterial blood-gas tensions and radiological appearances have all been used to detect its presence. At Clare Hall Chest Hospital routine radiological follow-up examination on the first postoperative day of patients undergoing left thoracotomy for repair of hiatus hernia revealed an unexpectedly high incidence of atelectasis in the lower zone of the contralateral dependent right lung. Similar changes in the contralateral dependent lung had previously been described by Craig, Bromley and Williams (1962) in a series of patients undergoing thoracotomy for a variety of cardiac and pulmonary operations. Investigation of the absorption times of different gases from the animal lung in the presence of complete bronchial obstruction led Coryllos
and Birnbaum in 1932 to consider that a relatively insoluble gas such as nitrogen might protect against collapse of alveoli filled with more soluble gases such as oxygen and nitrous oxide. More recently, Bendixen, Hedley White and Laver (1963) recommended that periodic hyperinflation of the lungs during pressure preset ventilation might afford protection against the development of atelectasis. In view of the high incidence of radiological evidence of atelectasis occurring on the first postoperative day, it was decided to investigate the value of these measures in avoiding this radiologically demonstrable complication. METHODS
The 326 patients described in this study were free from gross cardiopulmonary disease and had normal routine chest X-rays 24 hours before left thoracotomy for repair of hiatus hernia. A chest film was taken in the ward on the first postoperative day with the patient in the sitting position, and thereafter daily for at least five days. All X-rays were examined by one of us (U.O'C.) who DOREEN R. G. BROWNE,* M.B., F.FJV.R.C.S., D.CH., D.OBSTJtc.o.G., J. ROCHFORD, M.B., F.F^JLC.S., U.
CCONNELL, M.B., D.M.R., d a r e Hall Chest Hospital, Hertfordshire; J. G. JONES, M.D., MJLOP., F . F X R . C A ,
University of Birmingham Department of Anaesthesia, Quten Elizabeth Hospital, Birmingham. • Present address: Massachusetts General Hospital, Boston, U.S.A.
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Radiological evidence of postoperative atelectasis in the lower zone of the dependent contralateral right lung occurred in 50.8 per cent of patients who had undergone a left thoracotomy for repair of hiatus hernia between the years 1960-66. This condition was clinically asymptomatic and was not related to the age and sex of the patient, the presence of pre-operative chronic bronchitis or the presence of air under the right diaphragm. The substitution of a nitrogen-containing mixture for nitrous oxide in the inspired gases throughout the operation was associated with a highly significant reduction in the incidence of postoperative atelectasis in the dependent lung from 50.8 to 24.0 per cent, while postoperative hyperinflation with 100 per cent oxygen following the use of nitrous oxide during anaesthesia was without significant effect.
INCIDENCE OF POSTOPERATIVE ATELECTASIS
341
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was unaware of the anaesthetic technique used. gave a history of a productive cough occurring For the purposes of this study the presence of an on most days for three months of the year during abnormal peripheral opacity in the contralateral at least two years (Ciba Symposium, 1959). The 226 patients ranged in age from 12 to 78 dependent lung appearing in the film taken on the first postoperative day was taken as a positive years (mean 57); 77 men were aged 12-78 years finding. The presence of air under the right (mean 54) and 149 women were aged 25-77 diaphragm was also noted during the study. years (mean 59). Furthermore, it was seen from the study that this Pre-operative medication consisted of pethidine atelectasis was localized predominantly in the 100 mg, promethazine 25 mg and atropine 0.6 lower zone with only occasional involvement of mg. Anaesthesia was induced with sodium thiothe middle zone. pentone 250-500 mg followed by suxamethonium Three groups of patients were studied. In 50 mg. After topical application of 80 mg lignoGroup I the incidence of atelectasis occurring in caine solution to the larynx and trachea, a cuffed the dependent right lung in 226 patients who had endotracheal tube was introduced. After curarizaundergone thoracotomy for this procedure tion all patients were ventilated by a volumebetween 1960-66 was ascertained by restrospec- cycled Barnet ventilator using nitrous oxide 6 tive examination of pre- and postoperative chest l./min, oxygen 2 l./min and halothane 0.5 per cent via a non-return system. The inspiratory: exradiographs. In Group II the effects of immediate post- piratory time ratio was 1.5:3.5 with a set rate of operative hyperinflation in 50 patients who 12 b.pjn. Reversal of curarization was routinely received two kinds of premedication were studied achieved using neostigmine 2.5 mg and atropine prospectively. In Group HI the effects of anaes- 1.2 mg. Aspiration of secretions from the lungs thesia with a mixture containing air in a further was followed by inflation with 100 per cent 50 patients all given the same premedication were oxygen before exrubation in the supine position. noted. The patients in Group I (retrospective study) Group II (hyperinflation). Twenty-five patients were premedicated with were anaesthetized consecutively. The first 25 pethidine 100 mg, promethazine 25 mg and patients in Group II (hyperinflation series) were atropine 0.6 mg (premedication A) and 25 anaesthetized consecutively and the following 20 patients with droperidol 10 mg, atropine being cases were then anaesthetized alternately with 19 omitted (premedication B). All were anaesthetized cases from Group III (nitrogen mixture series). The remaining 5 cases in Group II and 31 cases as for Group I, but a double-lumen endoin Group HI were then anaesthetized consecu- bronchial tube was inserted for the specific purpose of hyperinflating each lung separately at the tively. end of operation. On the request of the surgeons, Throughout the period of investigation there the lung was deflated during a 30-minute period was no change in the surgical technique nor in whilst the hernia wat being repaired, although this the general management of all the patients in the was not the prime reason for the use of such a pre- and postoperative periods. The physio- tube. During this period the oxygen was increased therapy regime remained unaltered and this was to 50 per cent. begun immediately on return to the ward after After reversal of curarization and aspiration of operation and continued three times a day both bronchi each lung was inflated for 3-4 throughout the postoperative period together with routine antibiotic cover. Both regimes were seconds at 40 cm H a O with 100 per cent oxygen. unaffected by the development and course of This procedure was performed in the lateral and atelectasis which was apparent on the postopera- repeated in the supine positions at a rate of 12 b.p.m. for 5 minutes at die end of operation, after tive film. which the endobronchial tube was removed. Group I (retrospective survey). The sex and age of each patient was noted, as Group III (nitrogen mixture). Fifty patients were anaesthetized using the was the presence of pre-existing bronchitis, which was considered to be present if the patient single-lumen endotracheal tube in a manner
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BRITISH JOURNAL OF ANAESTHESIA
similar to that used in Group I, when both lungs were ventilated throughout. This group differed from Group I only in that premedication consisted of droperidol 10 mg alone (premedication B) and the anaesthetic gas mixture consisted of air 6 l./min, oxygen 2 l./min and halothane 0.5 per cent, air replacing nitrous oxide. At the end of operation both lungs were inflated using the air-oxygen mixture instead of 100 per cent oxygen. No deliberate measures were taken to hyperinflate these patients in the manner used in Group II.
(hyperinflation) Premedication A Premedication B
25 25
11 11
44.0 44.0
Total
50
22
44.0
50
12
24.0
Group III
Total
Atelectasis
Total
226
115
50.8
Males Females
77 149
49.3 51.7
Above 55 yr Below 55 yr
143 83
38 77 77 38
Air below right diaphragm Present Absent
103 123
51 64
49.5 52.0
53
25
47.1
53.8 45.7
173 90 52.02 There was no significant difference between the sex, age, air below the right diaphragm or bronchitis on the incidence of atelectasis.
The difference in incidence of atelectasis between Groups II and III was significant (P<0.025).
Hyperinflation of each lung with 100 per cent oxygen at the end of the operation (Group II) did not lead to a significant lowering of the overall incidence of atelectasis (table II). Atelectasis occurred equally frequently widi either form of premedication. The use of a nitrogen-containing mixture for pulmonary ventilation during operation in 50 patients was associated with a highly significant reduction of the incidence of atelectasis to 24 per cent (P<0.001) compared with the retrospective series and a significant reduction in the incidence compared with the hyperinflation group (P<0.025). The presence of air under the right diaphragm appeared to be without effect on
NTS
Atelectasis % incidence
% incidence
Group II
UJ
NUMBEROF FA
TABLE I
Results—Group I (retrospective). Showing the relationship between sex, age, subdiaphragmatic air and bronchitis on the incidence of atelectasis.
No pre-op. bronchitis
Atelectasis
20 15 10
0
2 3 A 5 1
7 8 9 10 H 12
POSTOPERATIVE DAY FIG. 1 Number of patients showing resolution of atelectasis in the postoperative period. The initial diagnosis of atelectasis was made on the first postoperative day.
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Retrospective examination of the chest X-rays of the 226 patients in Group I showed that the incidence of postoperative atelectasis in the lower zone of the contralateral dependent right lung was 50.8 per cent (table I). The incidence was similar in men and women. Pre-existing bronchitis was not associated with a change in the incidence of atelectasis in either men or women; the incidence was similar in those above and below the age of 55; nor was there a difference in the incidence of atelectasis between those who had or had not radiological evidence of air below the right diaphragm.
Pre-op. bronchitis
Total
(nitrogen mixture)
RESULTS
Subjects
TABLE II
Showing the effects of premedication, postoperative hyperinflation, and breathing an anaesthetic mixture containing nitrogen on the incidence of postoperative atelectasis.
343
INCIDENCE OF POSTOPERATIVE ATELECTASIS TABLE III
Showing the results for the three groups of subjects tncluding the effects of air under the right diaphragm. Air below Atelectasis right % incidence diaphragm Atelectasis Total Group I (Retrospective series)
103 123
Total
226
Group II (Hyperinflation)
11 39 50
Group III (Nitrogen mixture)
10 40
Total
50
Present Absent
Present Absent
51 64
49.5 52.0
115
50.8
4 18
36.3 46.1
22
44.0
3 9
30.0 22.5
12
24.0
There was no significant effect on the incidence of atelectasis in any group resulting from the presence of air under the right diaphragm. There was a highly significant difference in the incidence of atelectasis between the pooled results of Groups I and III (P<0.001).
the development of atelectasis in the dependent lung in Groups II or HI (table HI). The pattern of resolution of atelectasis is shown in figure 1. It can be seen that after five days more than half the patients showed complete resolution. DISCUSSION
Extensive studies by aviation physiologists (Glaister, 1969) have demonstrated that the dependent lung airways may close in a variety of circumstances and if alveoli distal to these closed airways are filled with oxygen, they will tend to collapse when this gas is absorbed (Levy et al., 1962; Green and Burgess, 1962; Nolan et al., 1963). Chest radiographs showed that areas of atelectasis were confined to the most dependent lung tissue and although these changes were produced after exposing the lungs to accelerations several times the force of gravity at the same time as the lung bases were compressed with an antigravity suit, similar effects have been reported under normal gravitational force by Nunn et al. (1965) and by Burger and Macklem (1966) without extra-abdominal compression. Both of these groups of workers produced atelectasis in the dependent lung by breathing near residual volume (RV). The extensive studies of Milic-Emili and co-workers (1966) have elucidated the probable mechanisms influencing the susceptibility of the
most dependent airways to close at low lung volumes. They have shown that the intrapleural pressure in the dependent part of the lung exceeds that in the upper lung. On breathing out from total lung capacity the dependent lung empties and its elastic recoil falls more rapidly than the middle and upper parts of the lung. At about a litre above RV intrapleural pressure at the base of the lung will exceed the pressure within the airways of this region, and because of the low elastic recoil, the airways tend to close. This tendency of some airways to close at low lung volume is not confined to the lung base, but may occur in the apex when this part of the lung is dependent (Clarke, Jones and Glaister, 1969). It has also been observed that dependent airway closure tends to occur at progressively larger lung volumes with increasing age (Clarke and Jones, 1969; Milic-Emili, Leblanc and Ruff, 1970). In the present group of patients the changes observed in the dependent lung are in agreement with the results reported by Craig, Bromley and Williams (1962), and can be explained by a mechanism similar to that suggested by MilicEmili and co-workers (1966). When the left pleura is opened and the diaphragm incised, the forces maintaining the position of the mediastinum are reduced and it is displaced into the right
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Total
Present Absent
344
patients studied by Panday and Nunn (1968), nor was this gradient affected by variation of the inspiratory/expiratory time ratio in patients undergoing controlled ventilation (Lumley, Morgan and Sykes, 1968). The highly significant reduction in the incidence of dependent lung atelectasis in our series when nitrogen was introduced into the anaesthetic mixture supports the concept that collapse of the terminal airways is a function of the solubility of the contained gas and the degree of regional perfusion. The effect of nitrogen in reducing the collapse of alveoli distal to dosed airways has been studied by Green (1967) who demonstrated that as little as 20 per cent nitrogen added to the inspired oxygen markedly reduced the lung collapse following acceleration. Ernsting (1963) recommended 40 per cent nitrogen in oxygen to reduce flight-induced lung collapse and DuBois and associates (1966) showed that as little as 5 per cent nitrogen prevented lung collapse in a subject exposed to pure oxygen at reduced ambient pressure, whereas 2.5 per cent was insuffident. Until now clinical experience has not really supported this concept and although Nunn and associates (1965) suggested that breathing oxygen at low lung volumes was more likely to result in atelectasis than if the subject breathed air, in a later paper (Webb and Nunn, 1967) he was unable to demonstrate a statistical difference in the A-aDOj breathing an air mixture compared with a nitrous oxide-oxygen mixture, in patients breathing spontaneously, and in ventilated patients the A-aDo2 was significandy greater breathing a nitrogen-containing mixture. However, in the second group the mean inspired oxygen tension and the alveolar oxygen tension was greater in the nitrogen than in the nitrous oxide breathing group. It has been calculated (Farhi and Rahn, 1955) and demonstrated by many workers (Yokoyama, quoted by Rahn and Farhi, 1964) that the A-aDoa increases as the inspired oxygen concentration rises. Losing the data of Cole and Bishop (1963) it can be calculated that the increase in A-aDo2 in the nitrogen breathing group can be explained by the rise in PAO2, and it seems on this basis, for a given PAc3 gas exchange would be similar with eidier a nitrogen-containing mixture or one containing
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hemithorax. The dependent right lung is compressed and behaves as if it is at low lung volume having a diminished elastic recoil. The intrapleural pressure in this situation will tend to close some of the airways, trapping the gas in the distal alveoli. Depending upon the perfusion of the alveoli in the dosed zone, the solubility of its contained gas and the presence of collateral ventilation (Henderson, Horsfield and Cumming, 1969), there may or may not be an ensuing atelectasis. The apparent lack of the effect of age on the incidence of atelectasis may be due to the relatively few patients under 35 years in this study and the possibility of increased collateral ventilation reducing the effects in the older subjects and in those with bronchial disease. Several workers have considered measures which might protect against the development of postoperative atelectasis. As a result of measuring oxygen tensions during intra-abdominal surgery on patients undergoing pressure-regulated ventilation, Bendixen, Hedley White and Laver (1963) suggested that periodic hyperinflation of the lungs would tend to minimize atelectasis. The results based on radiological evidence obtained from our series of patients undergoing thoracotomy indicate no significant effect of this manoeuvre in reducing the incidence of postoperative atelectasis in the contralateral dependent right lung. The resolution of this atelectasis was incomplete in many subjects even after five days of routine deep breathing and physiotherapy. This was not unexpected when consideration was made of the force required to re-expand atelectatic terminal airways (Levine and Johnson, 1965). However, as pointed out by DuBois and associates (1966), the reasons why the lungs of some subjects remained collapsed while breathing a soluble gas and why there is recovery while breathing air are not entirely clear. Other groups of workers have also been unable to support the claims made for this technique. Fletcher and Barber (1966), using reduction of dynamic compliance as an index of atelectasis, demonstrated only a transient increase in this measurement following forced deep inspirations in normal volunteers breathing air then oxygen. Likewise hyperinflation of the lungs did not lead to an improvement in the alevolar arterial oxygen gradient in spontaneously breathing anaesthetized
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INCIDENCE OF POSTOPERATIVE ATELECTASIS
We suggest that factors such as posture, low lung volume, diminished lung elastic recoil, the open chest and gravity, will determine the susceptibility of airways to close. The solubility of gas trapped in the alveoli distal to these closed airways will determine the subsequent behaviour of these lung units. If at the onset of anaesthesia soluble gas is trapped in perfused alveoli, it is rapidly absorbed to give atelectasis and expansion of the affected lung will be difficult or even impossible. In the absence of distal collapse it may well be possible to improve the distribution of ventilation to the dependent lung by increasing the inflating pressures and thus the volume of the dependent lung which will improve the elastic recoil and reduce the tendency to airway closure. The reduced incidence of atelectasis in the nitrogen breathing group does not in any way imply an improvement in gas exchange, but simply conceals the fact that there may be trapped
gas giving rise to a shunt. The advantage of nitrogen is that in the presence of airway closure ventilation of the dependent parts of the lungs remains a practical possibility both during the operation and in the postoperative period. ACKNOWLEDGEMENTS
We are grateful to Mr. Cyril James for allowing access to his patients for this study and to Dr. J. Lewis for his co-operation. We are particularly indebted to Mrs. Green in the Radiology Department, Mrs. Francis and Miss Newlands in the Records Department and to Mrs. A. Hibbert for typing the manuscript. REFERENCES
Bendixen, H. H., Hedley White, J., and Laver, M. B. (1963). Impaired oxygenation in surgical patients during general anesthesia with controlled ventilation. New Engl. J. Med., 269, 991. Burger, E. J., and Macklem, P. T. (1966). The effect on lungs of breathing 100% oxygen near residual volume. Fed. Proc., 25, 566. Ciba Symposium (1959). Thorax, 14, 286. Clarke, S. W., and Jones, J. G. (1969). Influence of age on basal airway closure. Brit. J. Anaesth., 41, 556. Glaister, D. H. (1969). Change in pulmonary ventilation in different postures. Clin. Sri., 37, 357. Cole, R. B., and Bishop, J. M. (1963). Effect of varying inspired O, tension on alveolar-arterial O, tension difference in man. J. appi. Physiol, 18(6), 1043. Coryllos, P. N., and Bimbaum, G. I. (1932). Studies in pulmonary gas absorption in bronchial obstruction. Amer. J. med. Sci., 183, 317. Craig, J. O. C , Bromley, D. D., and Williams, R. (1962). Thoracotomy and the contralateral lung: a study of the changes occurring in the dependent and contralateral lung during and after thoracotomy in lateral decubitus. Thorax, 17, 9. Cumming, G., Horsfield, K., Jones, J. G., and Muir, D. C F. (1967). The influence of gaseous diffusion on the alveolar plateau at different lung volumes. Resp. PhysioL, % 386. DuBois, A. B., Turaids, T., Mammen, R. E., and Nobrega, F. T. (1966). Pulmonary atelectasis in subjects breathing oxygen at sea level or at simulated altitude. J. appl. Physiol, 21, 828. Emsting, J. (1963). The ideal relationship between inspired oxygen concentrations and cabin altitude. Aerospace Med., 34, 991. Farhi, L. E. (1966). Ventilation-perfusion relationship and its role in alveolar gas exchange. Advances in Respiratory Physiology fed. Caro, E. C), Chap. 5, p. 148. London: Arnold. Rahn, H. (1955). A theoretical analysis of the alveolar-arterial oxygen difference, with special reference to the distribution effect J. appl. Physiol, 7, 699. Fletcher, Grant, and Barber, J. L. (1966). Lung mechanics and physiologic shunt during spontaneous breathing in normal subjects. Anesthesiology, 27, 638. Glaister, D. H. (1969). Lung collapse in aviation medicine. Brit. J. Hosp. Med., 3, 635.
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only oxygen and nitrous oxide during spontaneous or mechanical ventilation. The work of Kaneko and associates (1966), Jones (1967) and Mflic-Emili, Lublanc and Ruff (1970) suggests that there will be a considerable redistribution of ventilation on assuming the supine position and although dependent airways may close in old subjects, V/Q inequalities will make a considerable contribution to the A-aDo2, but can only be accurately quantitated with the alveolar arterial nitrogen difference technique (Farhi, 1966). Recent analysis of the flow of gas through the airways has underlined the fact that mass movement of gas and therefore flow resistance is exceedingly small in the terminal airways, and that gas transport in the terminal airways is carried out by molecular diffusion (Cumming et al., 1967). Calculation of the uptake of pure nitrous oxide from one alveolated terminal airway unit distal to a terminal bronchiole suggests that even in the presence of considerable narrowing of terminal bronchioles sufficient to give rise to severe ventilation-perfusion inequality, the flow of gas into the alveoli to replace the gas lost into the blood will be maintained by diffusion and no change in size of the alveoli will occur. Thus collapse of alveolated airways seems likely to occur only in the presence of complete closure of more proximal airways.
346
Rahn, H., and Farhi, L. E. (1964). Ventilation, perfusion and gas exchange—the V A / Q concept. Handbook of Physiology, Sect. 3, "Respiration", VoL I, p. 735. Washington, D . C : American PhvsioL Soc Webb, S. J. S., and Nunn, J. F. (1967). A comparison between the effect of nitrous oxide and nitrogen on arterial Po,. Anaesthesia, 22, 69. LA FREQUENCE D E L'ATELECTASIE POSTOPERATOIRE D A N S LE POUMON DEPENDANT APRES THORACOTOMIE: LA VALEUR D E L'ADDITION D'AZOTE SOMMAIRE
Une evidence radiologique d'atelectasie postoperatoire dans la zone inferieure du poumon droit contralateral dependant se manifesto chez 50,8 pourcent des patients, qui avaient subi dans les annees 1960-1966 une thoracotomie gauche pour reparation d'hemie hiatale. Cet etat £tait diniquement asymptomatique et sans relation avec l'age et le sexe du malade, l'existence de bronchite chronique preoperatoire ou la presence d'air sous le diaphragme droit. La substitution d'un melange contenant de l'azote au protoxyde d'azote dans les gaz d'inspiration durant l'operation s'associa a une reduction tres significative de l'incidence de 1'atilectasie postoperatoire dans le poumon dependant de 50,8 a 24,0 pourcent, tandis que lTiyperinflation postoperatoire avec de l'oxygene a 100 pourcent apres 1'utUisation de protoxyde d'azote durant 1'anesthesie n'eut pas d'effet significauf. DIE INZIDENZ VON POSTOPERATIVEN ATELEKTASEN I N D E N ABHANGIGEN LUNGENPARTIEN NACH THORAKOTOMIE: DER WERT EINES ZUSATZES VON STICKSTOFF ZUSAMMENFASSUNG
Bei 50,8 Prozent der Patienten, die sich zwischen 1960-1966 einer linksseitigen Thorakotomie zur operativen Revision einer Hiatushernie zu unterziehen hatten, wurde der radiologische Nachweis von postoperativen Atelektasen in der unteren Region der abhangigen kontralateralen rechten Lunge erbracht. Dieser Zustand verhef klinisch ohne Symptome und stand in keiner Beziehung zu Alter und Geschlecht des Patienten, zum praoperativen Vorliegen einer chronischen Bronchitis oder dem Vorhandensein von Luft unter dem rechten ZwerchfelL Wenn wahrend der Operationsdauer bei den eingeatmeten Gasen Lachgas durch ein Stickstoff enthaltendes Gemisch ersetzt wurde hatte dies cine hochsignifikante Reduzierung der Inzidenz von postoperativen Atelektasen in der abhangigen Lunge—von 50,8 Prozent auf 24,0 Prozent—zur Folge, wahrend eine postoperativ durchgefuhrte Hyperinflation mit 100 Prozent Sauerstoff nach der Applikation von Lachgas wahrend der Narkose ohne wesentlichen Effekt war.
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Green, I. D. (1967). The pathogenesis and physiological effects of pulmonary collapse induced by breathing oxygen and increased gravitational force. PhJD. Thesis, University of London. Burgess, B. F. (1962). An investigation into the major factors contributing to post-flight chest pain in fighter pilots. Flying Personnel Research Committee Report No. 1182. London: Ministry of Defence. Hamilton, W. K. (1961). Atelectasis, pneumothorax and aspiration as postoperative complications. Anesthesiology, 22, 708. Henderson, R., Horsfield, K., and Cumming, G. (1969). Intersegmental collateral ventilation in the human lung. Resp. Physiol, 6, 128. Jones, J. G. (1967). Ventilatory function in man. MX). Thesis, University of Birmingham. Jorg, E. (1935). Die Fotuslimge im gebomen kinde fur Pathologie, Therapie und Gerichtliche, p. 3. Arzbsiwissenschaft: Grimma. Kaneko, K., Milic-Emili, J., Dolovitch, M G., Dawson, A., and Bates, D. V. (1966). Regional distribution of ventilation and perfusion as a function of body position. J. appl. Physiol, 21, 767. Levine, B. E., and Johnson, R. P. (1965). Effect of atelectasis on pulmonary surfactant and quasistatic lung mechanics. J. appl. Physiol, 20, 859. Levy, P. M , Jaeger, E. A., Stone, R. S., and Doudna, C. T. (1962). Clinical problems in aviation medicine. Aeroatelectasis: a respiratory syndrome in aviators. Aerospace Med., 33, 988. Lumley, J., Morgan, M., and Sykes, M. K. (1968). Changes in alveolar arterial oxygen tension difference and physiological deadspace during controlled ventilation. Brit. J. Anaesth., 40, 803. Milic-Emili, J., Henderson, J. A. M , Dolovich, M B., Trop, D., and Kaneko, K. (1966). Regional distribution of inspired gas in the lung. J. appl. Physiol, 21, 749. Leblanc, T., and Ruff, F. (1970). Effect of age and body position on airway closure in man. Brit. J. Anaesth., 42, 86. Nolan, A. C , Marshall, H. W., Cronin, L., Sutterer, W. F., and Wood, E. H. (1963). Decreases in arterial oxygen saturation and associated changes in pressures and roentgenographic appearance of the thorax during forward ( + Gx) acceleration. Aerospace Med., 34, 797. Nunn, J. F., Coleman, A. J., Sm-hithnnnnHnrij T., Bergman, N. A., and Laws, J. W. (1965). Hypoxaemia and atelectasis produced by forced expiration. Brit. J. Anaesth., 37, 3. Panday, J., and Nunn, J. F. (1968). Failure to demonstrate progressive falls of arterial Po 3 during anaesthesia. Anaesthesia, 23, 38.
BRITISH JOURNAL OF ANAESTHESIA
THE INCIDENCE OF POSTOPERATIVE ATELECTASIS IN THE DEPENDENT LUNG FOLLOWING THORACOTOMY: THE VALUE OF ADDED NITROGEN BY
DOREEN R. G. BROWNE, J. ROCHFORD, U. O'CONNELL AND J. G. JONES SUMMARY
Originally the term "atelectasis" was coined from the Greek words "ateles" meaning imperfect and "ektasis" meaning expansion, by Jorg in 1835, but it has been more recently described by Hamilton (1961) as a condition in which there is collapse of one or more definite anatomical units of the lung. Atelectasis of a lobule, segment, lobe or entire lung may occur and the incidence of this condition after operation has been shown to vary depending on the criteria of measurement. Clinical signs including displacement of the apex beat, tachycardia and fever, changes in the pulmonary function tests, arterial blood-gas tensions and radiological appearances have all been used to detect its presence. At Clare Hall Chest Hospital routine radiological follow-up examination on the first postoperative day of patients undergoing left thoracotomy for repair of hiatus hernia revealed an unexpectedly high incidence of atelectasis in the lower zone of the contralateral dependent right lung. Similar changes in the contralateral dependent lung had previously been described by Craig, Bromley and Williams (1962) in a series of patients undergoing thoracotomy for a variety of cardiac and pulmonary operations. Investigation of the absorption times of different gases from the animal lung in the presence of complete bronchial obstruction led Coryllos
and Birnbaum in 1932 to consider that a relatively insoluble gas such as nitrogen might protect against collapse of alveoli filled with more soluble gases such as oxygen and nitrous oxide. More recently, Bendixen, Hedley White and Laver (1963) recommended that periodic hyperinflation of the lungs during pressure preset ventilation might afford protection against the development of atelectasis. In view of the high incidence of radiological evidence of atelectasis occurring on the first postoperative day, it was decided to investigate the value of these measures in avoiding this radiologically demonstrable complication. METHODS
The 326 patients described in this study were free from gross cardiopulmonary disease and had normal routine chest X-rays 24 hours before left thoracotomy for repair of hiatus hernia. A chest film was taken in the ward on the first postoperative day with the patient in the sitting position, and thereafter daily for at least five days. All X-rays were examined by one of us (U.O'C.) who DOREEN R. G. BROWNE,* M.B., F.FJV.R.C.S., D.CH., D.OBSTJtc.o.G., J. ROCHFORD, M.B., F.F^JLC.S., U.
CCONNELL, M.B., D.M.R., d a r e Hall Chest Hospital, Hertfordshire; J. G. JONES, M.D., MJLOP., F . F X R . C A ,
University of Birmingham Department of Anaesthesia, Quten Elizabeth Hospital, Birmingham. • Present address: Massachusetts General Hospital, Boston, U.S.A.
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Radiological evidence of postoperative atelectasis in the lower zone of the dependent contralateral right lung occurred in 50.8 per cent of patients who had undergone a left thoracotomy for repair of hiatus hernia between the years 1960-66. This condition was clinically asymptomatic and was not related to the age and sex of the patient, the presence of pre-operative chronic bronchitis or the presence of air under the right diaphragm. The substitution of a nitrogen-containing mixture for nitrous oxide in the inspired gases throughout the operation was associated with a highly significant reduction in the incidence of postoperative atelectasis in the dependent lung from 50.8 to 24.0 per cent, while postoperative hyperinflation with 100 per cent oxygen following the use of nitrous oxide during anaesthesia was without significant effect.
INCIDENCE OF POSTOPERATIVE ATELECTASIS
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was unaware of the anaesthetic technique used. gave a history of a productive cough occurring For the purposes of this study the presence of an on most days for three months of the year during abnormal peripheral opacity in the contralateral at least two years (Ciba Symposium, 1959). The 226 patients ranged in age from 12 to 78 dependent lung appearing in the film taken on the first postoperative day was taken as a positive years (mean 57); 77 men were aged 12-78 years finding. The presence of air under the right (mean 54) and 149 women were aged 25-77 diaphragm was also noted during the study. years (mean 59). Furthermore, it was seen from the study that this Pre-operative medication consisted of pethidine atelectasis was localized predominantly in the 100 mg, promethazine 25 mg and atropine 0.6 lower zone with only occasional involvement of mg. Anaesthesia was induced with sodium thiothe middle zone. pentone 250-500 mg followed by suxamethonium Three groups of patients were studied. In 50 mg. After topical application of 80 mg lignoGroup I the incidence of atelectasis occurring in caine solution to the larynx and trachea, a cuffed the dependent right lung in 226 patients who had endotracheal tube was introduced. After curarizaundergone thoracotomy for this procedure tion all patients were ventilated by a volumebetween 1960-66 was ascertained by restrospec- cycled Barnet ventilator using nitrous oxide 6 tive examination of pre- and postoperative chest l./min, oxygen 2 l./min and halothane 0.5 per cent via a non-return system. The inspiratory: exradiographs. In Group II the effects of immediate post- piratory time ratio was 1.5:3.5 with a set rate of operative hyperinflation in 50 patients who 12 b.pjn. Reversal of curarization was routinely received two kinds of premedication were studied achieved using neostigmine 2.5 mg and atropine prospectively. In Group HI the effects of anaes- 1.2 mg. Aspiration of secretions from the lungs thesia with a mixture containing air in a further was followed by inflation with 100 per cent 50 patients all given the same premedication were oxygen before exrubation in the supine position. noted. The patients in Group I (retrospective study) Group II (hyperinflation). Twenty-five patients were premedicated with were anaesthetized consecutively. The first 25 pethidine 100 mg, promethazine 25 mg and patients in Group II (hyperinflation series) were atropine 0.6 mg (premedication A) and 25 anaesthetized consecutively and the following 20 patients with droperidol 10 mg, atropine being cases were then anaesthetized alternately with 19 omitted (premedication B). All were anaesthetized cases from Group III (nitrogen mixture series). The remaining 5 cases in Group II and 31 cases as for Group I, but a double-lumen endoin Group HI were then anaesthetized consecu- bronchial tube was inserted for the specific purpose of hyperinflating each lung separately at the tively. end of operation. On the request of the surgeons, Throughout the period of investigation there the lung was deflated during a 30-minute period was no change in the surgical technique nor in whilst the hernia wat being repaired, although this the general management of all the patients in the was not the prime reason for the use of such a pre- and postoperative periods. The physio- tube. During this period the oxygen was increased therapy regime remained unaltered and this was to 50 per cent. begun immediately on return to the ward after After reversal of curarization and aspiration of operation and continued three times a day both bronchi each lung was inflated for 3-4 throughout the postoperative period together with routine antibiotic cover. Both regimes were seconds at 40 cm H a O with 100 per cent oxygen. unaffected by the development and course of This procedure was performed in the lateral and atelectasis which was apparent on the postopera- repeated in the supine positions at a rate of 12 b.p.m. for 5 minutes at die end of operation, after tive film. which the endobronchial tube was removed. Group I (retrospective survey). The sex and age of each patient was noted, as Group III (nitrogen mixture). Fifty patients were anaesthetized using the was the presence of pre-existing bronchitis, which was considered to be present if the patient single-lumen endotracheal tube in a manner
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similar to that used in Group I, when both lungs were ventilated throughout. This group differed from Group I only in that premedication consisted of droperidol 10 mg alone (premedication B) and the anaesthetic gas mixture consisted of air 6 l./min, oxygen 2 l./min and halothane 0.5 per cent, air replacing nitrous oxide. At the end of operation both lungs were inflated using the air-oxygen mixture instead of 100 per cent oxygen. No deliberate measures were taken to hyperinflate these patients in the manner used in Group II.
(hyperinflation) Premedication A Premedication B
25 25
11 11
44.0 44.0
Total
50
22
44.0
50
12
24.0
Group III
Total
Atelectasis
Total
226
115
50.8
Males Females
77 149
49.3 51.7
Above 55 yr Below 55 yr
143 83
38 77 77 38
Air below right diaphragm Present Absent
103 123
51 64
49.5 52.0
53
25
47.1
53.8 45.7
173 90 52.02 There was no significant difference between the sex, age, air below the right diaphragm or bronchitis on the incidence of atelectasis.
The difference in incidence of atelectasis between Groups II and III was significant (P<0.025).
Hyperinflation of each lung with 100 per cent oxygen at the end of the operation (Group II) did not lead to a significant lowering of the overall incidence of atelectasis (table II). Atelectasis occurred equally frequently widi either form of premedication. The use of a nitrogen-containing mixture for pulmonary ventilation during operation in 50 patients was associated with a highly significant reduction of the incidence of atelectasis to 24 per cent (P<0.001) compared with the retrospective series and a significant reduction in the incidence compared with the hyperinflation group (P<0.025). The presence of air under the right diaphragm appeared to be without effect on
NTS
Atelectasis % incidence
% incidence
Group II
UJ
NUMBEROF FA
TABLE I
Results—Group I (retrospective). Showing the relationship between sex, age, subdiaphragmatic air and bronchitis on the incidence of atelectasis.
No pre-op. bronchitis
Atelectasis
20 15 10
0
2 3 A 5 1
7 8 9 10 H 12
POSTOPERATIVE DAY FIG. 1 Number of patients showing resolution of atelectasis in the postoperative period. The initial diagnosis of atelectasis was made on the first postoperative day.
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Retrospective examination of the chest X-rays of the 226 patients in Group I showed that the incidence of postoperative atelectasis in the lower zone of the contralateral dependent right lung was 50.8 per cent (table I). The incidence was similar in men and women. Pre-existing bronchitis was not associated with a change in the incidence of atelectasis in either men or women; the incidence was similar in those above and below the age of 55; nor was there a difference in the incidence of atelectasis between those who had or had not radiological evidence of air below the right diaphragm.
Pre-op. bronchitis
Total
(nitrogen mixture)
RESULTS
Subjects
TABLE II
Showing the effects of premedication, postoperative hyperinflation, and breathing an anaesthetic mixture containing nitrogen on the incidence of postoperative atelectasis.
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INCIDENCE OF POSTOPERATIVE ATELECTASIS TABLE III
Showing the results for the three groups of subjects tncluding the effects of air under the right diaphragm. Air below Atelectasis right % incidence diaphragm Atelectasis Total Group I (Retrospective series)
103 123
Total
226
Group II (Hyperinflation)
11 39 50
Group III (Nitrogen mixture)
10 40
Total
50
Present Absent
Present Absent
51 64
49.5 52.0
115
50.8
4 18
36.3 46.1
22
44.0
3 9
30.0 22.5
12
24.0
There was no significant effect on the incidence of atelectasis in any group resulting from the presence of air under the right diaphragm. There was a highly significant difference in the incidence of atelectasis between the pooled results of Groups I and III (P<0.001).
the development of atelectasis in the dependent lung in Groups II or HI (table HI). The pattern of resolution of atelectasis is shown in figure 1. It can be seen that after five days more than half the patients showed complete resolution. DISCUSSION
Extensive studies by aviation physiologists (Glaister, 1969) have demonstrated that the dependent lung airways may close in a variety of circumstances and if alveoli distal to these closed airways are filled with oxygen, they will tend to collapse when this gas is absorbed (Levy et al., 1962; Green and Burgess, 1962; Nolan et al., 1963). Chest radiographs showed that areas of atelectasis were confined to the most dependent lung tissue and although these changes were produced after exposing the lungs to accelerations several times the force of gravity at the same time as the lung bases were compressed with an antigravity suit, similar effects have been reported under normal gravitational force by Nunn et al. (1965) and by Burger and Macklem (1966) without extra-abdominal compression. Both of these groups of workers produced atelectasis in the dependent lung by breathing near residual volume (RV). The extensive studies of Milic-Emili and co-workers (1966) have elucidated the probable mechanisms influencing the susceptibility of the
most dependent airways to close at low lung volumes. They have shown that the intrapleural pressure in the dependent part of the lung exceeds that in the upper lung. On breathing out from total lung capacity the dependent lung empties and its elastic recoil falls more rapidly than the middle and upper parts of the lung. At about a litre above RV intrapleural pressure at the base of the lung will exceed the pressure within the airways of this region, and because of the low elastic recoil, the airways tend to close. This tendency of some airways to close at low lung volume is not confined to the lung base, but may occur in the apex when this part of the lung is dependent (Clarke, Jones and Glaister, 1969). It has also been observed that dependent airway closure tends to occur at progressively larger lung volumes with increasing age (Clarke and Jones, 1969; Milic-Emili, Leblanc and Ruff, 1970). In the present group of patients the changes observed in the dependent lung are in agreement with the results reported by Craig, Bromley and Williams (1962), and can be explained by a mechanism similar to that suggested by MilicEmili and co-workers (1966). When the left pleura is opened and the diaphragm incised, the forces maintaining the position of the mediastinum are reduced and it is displaced into the right
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Total
Present Absent
344
patients studied by Panday and Nunn (1968), nor was this gradient affected by variation of the inspiratory/expiratory time ratio in patients undergoing controlled ventilation (Lumley, Morgan and Sykes, 1968). The highly significant reduction in the incidence of dependent lung atelectasis in our series when nitrogen was introduced into the anaesthetic mixture supports the concept that collapse of the terminal airways is a function of the solubility of the contained gas and the degree of regional perfusion. The effect of nitrogen in reducing the collapse of alveoli distal to dosed airways has been studied by Green (1967) who demonstrated that as little as 20 per cent nitrogen added to the inspired oxygen markedly reduced the lung collapse following acceleration. Ernsting (1963) recommended 40 per cent nitrogen in oxygen to reduce flight-induced lung collapse and DuBois and associates (1966) showed that as little as 5 per cent nitrogen prevented lung collapse in a subject exposed to pure oxygen at reduced ambient pressure, whereas 2.5 per cent was insuffident. Until now clinical experience has not really supported this concept and although Nunn and associates (1965) suggested that breathing oxygen at low lung volumes was more likely to result in atelectasis than if the subject breathed air, in a later paper (Webb and Nunn, 1967) he was unable to demonstrate a statistical difference in the A-aDOj breathing an air mixture compared with a nitrous oxide-oxygen mixture, in patients breathing spontaneously, and in ventilated patients the A-aDo2 was significandy greater breathing a nitrogen-containing mixture. However, in the second group the mean inspired oxygen tension and the alveolar oxygen tension was greater in the nitrogen than in the nitrous oxide breathing group. It has been calculated (Farhi and Rahn, 1955) and demonstrated by many workers (Yokoyama, quoted by Rahn and Farhi, 1964) that the A-aDoa increases as the inspired oxygen concentration rises. Losing the data of Cole and Bishop (1963) it can be calculated that the increase in A-aDo2 in the nitrogen breathing group can be explained by the rise in PAO2, and it seems on this basis, for a given PAc3 gas exchange would be similar with eidier a nitrogen-containing mixture or one containing
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hemithorax. The dependent right lung is compressed and behaves as if it is at low lung volume having a diminished elastic recoil. The intrapleural pressure in this situation will tend to close some of the airways, trapping the gas in the distal alveoli. Depending upon the perfusion of the alveoli in the dosed zone, the solubility of its contained gas and the presence of collateral ventilation (Henderson, Horsfield and Cumming, 1969), there may or may not be an ensuing atelectasis. The apparent lack of the effect of age on the incidence of atelectasis may be due to the relatively few patients under 35 years in this study and the possibility of increased collateral ventilation reducing the effects in the older subjects and in those with bronchial disease. Several workers have considered measures which might protect against the development of postoperative atelectasis. As a result of measuring oxygen tensions during intra-abdominal surgery on patients undergoing pressure-regulated ventilation, Bendixen, Hedley White and Laver (1963) suggested that periodic hyperinflation of the lungs would tend to minimize atelectasis. The results based on radiological evidence obtained from our series of patients undergoing thoracotomy indicate no significant effect of this manoeuvre in reducing the incidence of postoperative atelectasis in the contralateral dependent right lung. The resolution of this atelectasis was incomplete in many subjects even after five days of routine deep breathing and physiotherapy. This was not unexpected when consideration was made of the force required to re-expand atelectatic terminal airways (Levine and Johnson, 1965). However, as pointed out by DuBois and associates (1966), the reasons why the lungs of some subjects remained collapsed while breathing a soluble gas and why there is recovery while breathing air are not entirely clear. Other groups of workers have also been unable to support the claims made for this technique. Fletcher and Barber (1966), using reduction of dynamic compliance as an index of atelectasis, demonstrated only a transient increase in this measurement following forced deep inspirations in normal volunteers breathing air then oxygen. Likewise hyperinflation of the lungs did not lead to an improvement in the alevolar arterial oxygen gradient in spontaneously breathing anaesthetized
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INCIDENCE OF POSTOPERATIVE ATELECTASIS
We suggest that factors such as posture, low lung volume, diminished lung elastic recoil, the open chest and gravity, will determine the susceptibility of airways to close. The solubility of gas trapped in the alveoli distal to these closed airways will determine the subsequent behaviour of these lung units. If at the onset of anaesthesia soluble gas is trapped in perfused alveoli, it is rapidly absorbed to give atelectasis and expansion of the affected lung will be difficult or even impossible. In the absence of distal collapse it may well be possible to improve the distribution of ventilation to the dependent lung by increasing the inflating pressures and thus the volume of the dependent lung which will improve the elastic recoil and reduce the tendency to airway closure. The reduced incidence of atelectasis in the nitrogen breathing group does not in any way imply an improvement in gas exchange, but simply conceals the fact that there may be trapped
gas giving rise to a shunt. The advantage of nitrogen is that in the presence of airway closure ventilation of the dependent parts of the lungs remains a practical possibility both during the operation and in the postoperative period. ACKNOWLEDGEMENTS
We are grateful to Mr. Cyril James for allowing access to his patients for this study and to Dr. J. Lewis for his co-operation. We are particularly indebted to Mrs. Green in the Radiology Department, Mrs. Francis and Miss Newlands in the Records Department and to Mrs. A. Hibbert for typing the manuscript. REFERENCES
Bendixen, H. H., Hedley White, J., and Laver, M. B. (1963). Impaired oxygenation in surgical patients during general anesthesia with controlled ventilation. New Engl. J. Med., 269, 991. Burger, E. J., and Macklem, P. T. (1966). The effect on lungs of breathing 100% oxygen near residual volume. Fed. Proc., 25, 566. Ciba Symposium (1959). Thorax, 14, 286. Clarke, S. W., and Jones, J. G. (1969). Influence of age on basal airway closure. Brit. J. Anaesth., 41, 556. Glaister, D. H. (1969). Change in pulmonary ventilation in different postures. Clin. Sri., 37, 357. Cole, R. B., and Bishop, J. M. (1963). Effect of varying inspired O, tension on alveolar-arterial O, tension difference in man. J. appi. Physiol, 18(6), 1043. Coryllos, P. N., and Bimbaum, G. I. (1932). Studies in pulmonary gas absorption in bronchial obstruction. Amer. J. med. Sci., 183, 317. Craig, J. O. C , Bromley, D. D., and Williams, R. (1962). Thoracotomy and the contralateral lung: a study of the changes occurring in the dependent and contralateral lung during and after thoracotomy in lateral decubitus. Thorax, 17, 9. Cumming, G., Horsfield, K., Jones, J. G., and Muir, D. C F. (1967). The influence of gaseous diffusion on the alveolar plateau at different lung volumes. Resp. PhysioL, % 386. DuBois, A. B., Turaids, T., Mammen, R. E., and Nobrega, F. T. (1966). Pulmonary atelectasis in subjects breathing oxygen at sea level or at simulated altitude. J. appl. Physiol, 21, 828. Emsting, J. (1963). The ideal relationship between inspired oxygen concentrations and cabin altitude. Aerospace Med., 34, 991. Farhi, L. E. (1966). Ventilation-perfusion relationship and its role in alveolar gas exchange. Advances in Respiratory Physiology fed. Caro, E. C), Chap. 5, p. 148. London: Arnold. Rahn, H. (1955). A theoretical analysis of the alveolar-arterial oxygen difference, with special reference to the distribution effect J. appl. Physiol, 7, 699. Fletcher, Grant, and Barber, J. L. (1966). Lung mechanics and physiologic shunt during spontaneous breathing in normal subjects. Anesthesiology, 27, 638. Glaister, D. H. (1969). Lung collapse in aviation medicine. Brit. J. Hosp. Med., 3, 635.
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only oxygen and nitrous oxide during spontaneous or mechanical ventilation. The work of Kaneko and associates (1966), Jones (1967) and Mflic-Emili, Lublanc and Ruff (1970) suggests that there will be a considerable redistribution of ventilation on assuming the supine position and although dependent airways may close in old subjects, V/Q inequalities will make a considerable contribution to the A-aDo2, but can only be accurately quantitated with the alveolar arterial nitrogen difference technique (Farhi, 1966). Recent analysis of the flow of gas through the airways has underlined the fact that mass movement of gas and therefore flow resistance is exceedingly small in the terminal airways, and that gas transport in the terminal airways is carried out by molecular diffusion (Cumming et al., 1967). Calculation of the uptake of pure nitrous oxide from one alveolated terminal airway unit distal to a terminal bronchiole suggests that even in the presence of considerable narrowing of terminal bronchioles sufficient to give rise to severe ventilation-perfusion inequality, the flow of gas into the alveoli to replace the gas lost into the blood will be maintained by diffusion and no change in size of the alveoli will occur. Thus collapse of alveolated airways seems likely to occur only in the presence of complete closure of more proximal airways.
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Rahn, H., and Farhi, L. E. (1964). Ventilation, perfusion and gas exchange—the V A / Q concept. Handbook of Physiology, Sect. 3, "Respiration", VoL I, p. 735. Washington, D . C : American PhvsioL Soc Webb, S. J. S., and Nunn, J. F. (1967). A comparison between the effect of nitrous oxide and nitrogen on arterial Po,. Anaesthesia, 22, 69. LA FREQUENCE D E L'ATELECTASIE POSTOPERATOIRE D A N S LE POUMON DEPENDANT APRES THORACOTOMIE: LA VALEUR D E L'ADDITION D'AZOTE SOMMAIRE
Une evidence radiologique d'atelectasie postoperatoire dans la zone inferieure du poumon droit contralateral dependant se manifesto chez 50,8 pourcent des patients, qui avaient subi dans les annees 1960-1966 une thoracotomie gauche pour reparation d'hemie hiatale. Cet etat £tait diniquement asymptomatique et sans relation avec l'age et le sexe du malade, l'existence de bronchite chronique preoperatoire ou la presence d'air sous le diaphragme droit. La substitution d'un melange contenant de l'azote au protoxyde d'azote dans les gaz d'inspiration durant l'operation s'associa a une reduction tres significative de l'incidence de 1'atilectasie postoperatoire dans le poumon dependant de 50,8 a 24,0 pourcent, tandis que lTiyperinflation postoperatoire avec de l'oxygene a 100 pourcent apres 1'utUisation de protoxyde d'azote durant 1'anesthesie n'eut pas d'effet significauf. DIE INZIDENZ VON POSTOPERATIVEN ATELEKTASEN I N D E N ABHANGIGEN LUNGENPARTIEN NACH THORAKOTOMIE: DER WERT EINES ZUSATZES VON STICKSTOFF ZUSAMMENFASSUNG
Bei 50,8 Prozent der Patienten, die sich zwischen 1960-1966 einer linksseitigen Thorakotomie zur operativen Revision einer Hiatushernie zu unterziehen hatten, wurde der radiologische Nachweis von postoperativen Atelektasen in der unteren Region der abhangigen kontralateralen rechten Lunge erbracht. Dieser Zustand verhef klinisch ohne Symptome und stand in keiner Beziehung zu Alter und Geschlecht des Patienten, zum praoperativen Vorliegen einer chronischen Bronchitis oder dem Vorhandensein von Luft unter dem rechten ZwerchfelL Wenn wahrend der Operationsdauer bei den eingeatmeten Gasen Lachgas durch ein Stickstoff enthaltendes Gemisch ersetzt wurde hatte dies cine hochsignifikante Reduzierung der Inzidenz von postoperativen Atelektasen in der abhangigen Lunge—von 50,8 Prozent auf 24,0 Prozent—zur Folge, wahrend eine postoperativ durchgefuhrte Hyperinflation mit 100 Prozent Sauerstoff nach der Applikation von Lachgas wahrend der Narkose ohne wesentlichen Effekt war.
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Green, I. D. (1967). The pathogenesis and physiological effects of pulmonary collapse induced by breathing oxygen and increased gravitational force. PhJD. Thesis, University of London. Burgess, B. F. (1962). An investigation into the major factors contributing to post-flight chest pain in fighter pilots. Flying Personnel Research Committee Report No. 1182. London: Ministry of Defence. Hamilton, W. K. (1961). Atelectasis, pneumothorax and aspiration as postoperative complications. Anesthesiology, 22, 708. Henderson, R., Horsfield, K., and Cumming, G. (1969). Intersegmental collateral ventilation in the human lung. Resp. Physiol, 6, 128. Jones, J. G. (1967). Ventilatory function in man. MX). Thesis, University of Birmingham. Jorg, E. (1935). Die Fotuslimge im gebomen kinde fur Pathologie, Therapie und Gerichtliche, p. 3. Arzbsiwissenschaft: Grimma. Kaneko, K., Milic-Emili, J., Dolovitch, M G., Dawson, A., and Bates, D. V. (1966). Regional distribution of ventilation and perfusion as a function of body position. J. appl. Physiol, 21, 767. Levine, B. E., and Johnson, R. P. (1965). Effect of atelectasis on pulmonary surfactant and quasistatic lung mechanics. J. appl. Physiol, 20, 859. Levy, P. M , Jaeger, E. A., Stone, R. S., and Doudna, C. T. (1962). Clinical problems in aviation medicine. Aeroatelectasis: a respiratory syndrome in aviators. Aerospace Med., 33, 988. Lumley, J., Morgan, M., and Sykes, M. K. (1968). Changes in alveolar arterial oxygen tension difference and physiological deadspace during controlled ventilation. Brit. J. Anaesth., 40, 803. Milic-Emili, J., Henderson, J. A. M , Dolovich, M B., Trop, D., and Kaneko, K. (1966). Regional distribution of inspired gas in the lung. J. appl. Physiol, 21, 749. Leblanc, T., and Ruff, F. (1970). Effect of age and body position on airway closure in man. Brit. J. Anaesth., 42, 86. Nolan, A. C , Marshall, H. W., Cronin, L., Sutterer, W. F., and Wood, E. H. (1963). Decreases in arterial oxygen saturation and associated changes in pressures and roentgenographic appearance of the thorax during forward ( + Gx) acceleration. Aerospace Med., 34, 797. Nunn, J. F., Coleman, A. J., Sm-hithnnnnHnrij T., Bergman, N. A., and Laws, J. W. (1965). Hypoxaemia and atelectasis produced by forced expiration. Brit. J. Anaesth., 37, 3. Panday, J., and Nunn, J. F. (1968). Failure to demonstrate progressive falls of arterial Po 3 during anaesthesia. Anaesthesia, 23, 38.
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