recovery from aspiration pneumonitis

Pneumonologie 151,127--134 (1974) © by Springer-Verlag 1974

Recovery from Aspiration Pneumonitis

J. Steiner, M. Bachofen, and H. Bachofen

Departments of Anesthesiology and Medicine, Pulmonary Section, School of Medicine, University of Berne, Inselspital, Switzerland

Received August 15, 1974

Abstract. The pulmonary status of six patients was examined between five and seventeen months after they had been treated for aspiration pneumonitis. Patients with pre-existing lung and heart diseases were not included in this study. The evaluation based on clinical and radiological examinations, and on the results of pulmonary function tests, revealed a complete recovery in four patients. In two patients subnormal static lung volumes were the only abnormal findings, pointing to a slight though radiologically invisible pulmonary fibrosis as residual lung damage. However, during exercise arterial blood gases were normal in all patients. These results suggest that in patients without pre-existing lung disease aspiration pneumonitis is associated with a favorable prognosis once the patient has survived the acute phase of the disease.

Key words: Aspiration Pneumonitis - - Sequelae of Aspiration.

Aspiration of liquid gastric content is an extremely serious and often lethal complication of anesthesia and coma. The pathogenesis, morphologic and patho- physiological changes as well as the clinical manifestations of the ensuing inhalational pulmonary edema are well known [1--8]. In contrast to the numerous com- munications pertaining to the course of the acute phase of the illness, long-term follow-ups to assess eventual chronic lung damage and the corresponding degree of respiratory disability have been few and controversial [ g m l l ] . In this study atten- tion is exclusively directed to the late sequelae of aspiration pneumonitls. For this purpose six patients were thoroughly examined between 5 to 17 months after the occurrence of the aspiration.

Selection of Patients and Methods

All patients except one (the latter left the country shortly after discharge from the hospital) who had been treated in the intensive care unit of the University Hos- pital of Berne between 1970 and 1973, and who fulfilled the following criteria were included in this study: (1.) The diagnosis had to be well established. (2.) Only severe cases were considered: as judged by the chest roentgenograms at least 50°/0 of the lungs had to be involved showing the typical signs of airspace consolidation. (3.) Based on the history, previous physical examinations, and chest roentgenograms any patients with pre-existing lung or heart disease had to be ruled out; this cri- terion is indispensable for an unequivocal evaluation of the consequences of aspiration itself.

In five female patients aspiration occurred during induction of anesthesia: twice during emergency laparotomy because of intra-abdominal bleeding and acute ileus,

128 J. Steiner et al.

respectively, and three times during obstetrical surgery. The only male patient aspirated whilst in a coma after a traffic accident. A short history of each patient is given in the Appendix.

The therapeutic procedure was essentially the same in all patients. Without ex- ception intubation and assisted or controlled ventilation with PEEP was necessary. Nevertheless, three patients required inspiratory oxygen concentrations higher than 50°/0 in order to achieve an acceptable value of arterial oxygen tension. As a routine, broad spectrum antibiotics and high doses of steroids were given. After leaving the intensive care unit the patients remained in the hospital for a further one to three weeks and were treated with vigorous physiotherapy and inhalations.

The follow-ups included a careful history covering the period since the incident, physical examination, lateral and posterior-anterior chest roentgenograms, and pulmonary function tests. The evaluation of lung function was based on measurements of static and dynamic lung volumes, and of the arterial blood gases at rest and during steady-state exercise on a bicycle ergometer. Exercise loads varying between 100 and 170 watts were imposed taking the physical fitness of the patients into account.

Results

At the time of the follow-up only one patient (N. D.) complained about short- ness of breath during physical activities, five months after the incident. Other respiratory symptoms were absent in all patients. In particular, bronchitic episodes did not occur more frequently after the pneumonitis. The physical examination of the heart and lungs did not reveal any abnormal findings. The chest roentgenograms, as read by two independent observers, were absolutely normal. Neither fibrotic lesions nor hypertranslucent lung areas could be detected. The results of pulmonary function tests are shown in Table 1. The static lung volumes regained the predicted values in four patients; subnormal vital capacities and total lung volumes were found in two women: since both were of normal body build, neither asthenic nor obese, a residual restrictive pulmonary defect is the only explanation for this finding. In- deed, in both patients the pneumonitis was extremely severe, requiring controlled ventilation with PEEP and high oxygen concentrations for several days. In all cases, the FEVt was within the normal range. A normalization of pulmonary gas exchange was shown by normal arterial blood gases at rest and during exercise. The low COs-tensions combined with respiratory alkalosis at rest merely reflect the anxiety of some patients during the test.

Discussion

From the results of these follow-ups the prognosis of aspiration pneumonitis appears to be rather favorable once the patient has survived the acute phase of the disease. The clinical, radiological, and physiological findings indicate a far-reaching or even complete reversal of the severe pathologic changes. In particular, the normal arterial blood gases during exercise demonstrate that neither ventilation/per- fusion inequalities nor a diffusion impairement of a considerable degree persist [12]. Though invisible on the chest roentgenogram, a minimal fibrosis is mirrored by subnormal static lung volumes in two patients. In contrast to the patient described by

Aspiration Pneurnonitis 129

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Sladen and coworkers [9], no patient in this group developed extensive fibrosis. It has been shown in animal experiments that considerable pathologic alterations including the loss of capillaries can be repaired completely [17]. Why the repair of diffuse lung damage results in pulmonary fibrosis in some patients is not clear. Among other possibilities genetic factors may be involved. Furthermore, it is inter- esting to note that no signs of small airway disease could be detected in any of the patients. This result should be emphasized since a bronchiolitis fibrosa obliterans is


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abscissa. (F10~ = fraction of oxygen in the inspired air)

a frequent consequence of inhalational pulmonary edema due to irritant gases such as chlorine, nitrogen dioxide, and sulphur dioxide [13, 14].

The repair of extensive lung damage due to aspiration is slow. Fig. 1 illustrates the course of recovery of one patient (N. D.) with severe pneumonitis. The arterial oxygen tension during exercise returned to a normal level after about three months; the normalization of lung volumes seems to require even more time. In order to assess the degree of possible permanent lung damage any judgement should be de- layed until six to twelve months after the incident.

The favorable prognosis as revealed by this study should be seen in the light of the particular criteria applied for the selection of the patients. There is good reason to assume that aspiration pneumonitis is associated with a poorer prognosis in patients with pre-existing lung and heart disease or with other debilitating disorders. The mutual effect of the sudden exacerbation of the primary lung disease and the additional lung damage due to the aspiration probably increase both the mortality and morbidity. Moreover, the modalities of treatment for minimizing the destructive effect of aspiration and for avoiding secondary complications are noteworthy. Once the diagnosis had been established a vigorous therapy was started without delay. All patients were transferred to the intensive care unit. By early intubation and assisted ventilation three different aims were persued, i.e. the correction of vend- latory derangements, prevention of ateIectasis, and facilitation of bronchial cleansing by regular and careful endobronchial suctions. Indeed, some experimental evidence shows that immediate positive pressure ventilation may have a beneficial effect by itself [15, 16]. Broad spectrum antibiotics were given in order to counterbalance the increased susceptibility for suprainfection which would perpetuate the respiratory distress. However, daily bacteriologic examinations of bronchial secretions were con-

Aspiration Pneumonitis 131

sidered just as essential for effectively controlling pulmonary infections. High dosages of steroids were given to all patients [5, 8, 18], although the results of animal experiments are not unequivocal [15, 19]. Regular physiotherapy during the subacute phase of the disease (as described in the Appendix) appeared to benefit the recovery considerably. Admittedly, observations of a much larger number of patients are necessary for a final appraisal of the effectiveness of these therapeutic and preven- tive measures. In any case, all efforts during the acute phase of the illness, including the future application of a membrane oxygenator in critically ill patients, are justified in view of the good long-term outlook.

Appendix

Case 1: A. H., a 19-year-old male bicyclist was hit by a car. He lost consciousness due to brain concussion and was found on the roadside lying in a lateral body position with a right temporal scalp laceration. When admitted to the hospital he had regained consciousness but showed signs of respiratory distress. "/'he chest X-ray revealed extensive air space consolidation of the right lung (see Fig. 2). Diffuse subcrepitant rales were present over the entire right lung. He was intubated and ventilated with PEEP (5 cm H20). Brownish-frothy secretions were removed by endobronchial suctioning. By the next day the patient had im-

Fig. 2. Anterior-posterior chest roentgenogram of patient A. H. (see Appendix)


Fig. 3. Anterior-posterior chest roentgenogram of patient S. R. (see Appendix)

proved considerably. The patchy shadows over the right lung were less extensive; on breathing a gas mixture with an FIO2 (fraction of oxygen in inspired air) of 0.3 the arterial oxygen sa- turation was 93o/0. He was extubated and transferred to the ward. After being treated there with IPPB and physiotherapy the patient was discharged 8 days later in a good condition. At the time of the follow-up he was again an active member of a first league soccer team.

Case 2: S. R., a 44-year-old housewife was admitted to the hospital for hysterectomy. Four days later an emergency laparotomy had to be performed because of a paralytic ileus. During induction of anesthesia voluminous regurgitation occurred. After completion of surgery the patient was in severe respiratory distress. Clinically as well as radiologically the signs of bilateral, diffuse pulmonary edema were present (Fig. 3). She remained intubated, and controlled ventilation with 10 cm HeO of PEEP was started immediately. An inspiratory gas mixture with a FIO~ of 0.6 had to be given for 30 hrs to keep the arterial oxygen tension at a minimal level of 60 mm Hg. A readily detected bronchial infection with Esche- richia coli on the third day was effectively treated by alteration of the antibiotic therapy. By the fifth day the pulmonary status had improved considerably, and the weaning procedure was successful. At the time of discharge three weeks later the patient was still dyspneic on exercise. The chest X-ray was compatible with a diffuse interstitial lung disease and the lung function tests revealed a considerable restrictive defect.

Case 3: B. J., a 28-year-old woman underwent emergency surgery because of intra- abdominal bleeding which occurred after a tubal ligation was performed. She aspirated du-

Aspiration Pneumonitis 133

ring anesthesia and showed signs of progressive respiratory distress in the post-operative period. Diffuse tales were present over both lungs; the chest roentgenograms showed a bilateral, complete air space consolidation. The patient was reintubated without delay and ventilated with a volume cycled respirator. PEEP of 10 cm H.~O was applied. In spite of these measures she required pure oxygen during the first hours of treatment. For the next three days the inspired oxygen concentration was gradually lowered to 30%. From the fourth day on ventilation was assisted with a bird respirator until weaning could be at- tempted on the sixth day. The new chest X-ray showed a pattern of diffuse interstitial lung disease, and an atelectasis of the middle lobe. However, bronchoscopy revealed an open middle lobe bronchus. A restrictive pulmonary defect was confirmed by lung function tests. Intensive physiotherapy with regular IPPB-treatment was given during the subsequent weeks, and the pathological alterations showed a slow reversal.

Case 4: K. K., a 21-year-old nullipara regurgitated during inhalation anesthesia which was performed for a forceps extraction. In spite of immediate and extensive endotracheal suctioning she became dyspneic and cyanotic three hrs later. The chest roentgenogram revealed diffuse air space disease in both lower lung zones. She was transferred to the intensive care unit for the routine treatment as described in the method section. During the following 24 hrs her condition improved rapidly. The respiratory care was continued for nine more days with IPPB, inhalations, and physiotherapy. On the tenth day she was discharged without major respiratory symptoms. The chest X-ray had cleared almost completely.

Case 5: B. K., a 23-year-old nullipara vomited during induction of anesthesia following the injection of 100 mg of suxamethonium. The emergency anesthesia had to be done for a forceps extraction. Aspiration could not be avoided by cricoid pressure, and endotracheal suction yielded copious quantities of brownish secretions. After delivery of the baby the mother remained intubated and was transferred to the intensive care unit. The chest roentgenogram showed extensive aeinar shadows over both middle and lower lung zones. Venti- lation was assisted with a volume-cycled respirator, and an inspiratory O~-concentration of 40°/0 had to be administered. After 36 hrs the patient could be weaned. Physiotherapy was continued during the following six days on the ward.

Case 6: N. D., a 26-year-old mother of one child was admitted to the hospital for the second caesarean section, lntubation was not successful in spite of several trials, and the patient had to be ventilated with the mask. Immediately after the operation a labored re- spiration, cyanosis, and tachycardia were noted. These signs of respiratory distress showed a rapidly progressive course. Copious, dirty brown frothy secretions were removed by endotracheal suction. The chest roentgenogram showed bilateral white lungs. Artificial ventilation with a volume-cycled respirator had to be maintained for six days. PEEP of 10 cm H._,O was applied. Pure oxygen had to be given during the first 12 hrs. On the sixth day the patient was weaned from the respirator. Hospitalization was extended for three more weeks. On discharge, the chest roentgenogram showed a prominent reticulation of all lung zones. The degree of the restrictive pulmonary defect is shown in Fig. 1.

References

1. Cameron, J. L., Anderson, R. P., Zuldema, G. D.: Aspiration pneumonia. J. Surg. Res. 7, 44--53 (1967)

2. Cameron, J. L., Mitchell, W. H., Zuidema, G. D.: Aspiration pneumonia. Clinical out- come following documented aspiration. Arch. Surg. 106, 49--52 (1973)

3. Awe, W. C., Fletcher, W. S., Jacob, S. W.: The pathophysiology of aspiration pneumonitis. Surgery 60, 232--239 (1966)

4. Dines, D. E., Titus, J. L., Sessler, A. D.: Aspiration pneumonitis. Mayo Clin. Proc. 45, 347--360 (1970)

5. McCormick, P. W., Hay, R. G., Griffin, R. W.: Pulmonary aspiration of gastric contents in obstetric patients. Lancet 1, 1127--1130 (1966)

6. Exarhos, N. D., Logan, W. D., Abbott, O. A., Hatcher, C. R., jr.: The importance of pH and volume in tracheobronchial aspiration. Dis. Chest 47, 165--167 (1965)


7. Teabeaut, J. R.: Aspiration of gastric contents: experimental study. Amer. J. Path. 28, 51--67 (1952)

8. Bannister, W. K., Sattilaro, A. J.: Vomiting and aspiration during anesthesia. Anesthesiol- ogy 23, 251--264 (1952)

9. Sladen, A., Zanca, P., Haduott, W. H.: Aspiration pneumonitis--the sequelae. Chest 59, 448--450 (I971)

10. Hedden, M., Miller, G. J.: Mendelson's syndrome and its sequelae. Canad. Anaesth. Soc. J. 19, 351--359 (1972)

11. Adams, A. P., Morgan, M., Jones, B. C., McCormick, P. W.: A case of massive aspiration of gastric contents during obstetric anaesthesia. Brit. J. Anaesth. 41, 176--182 (1969)

12. Shepard, R. H.: Effect of pulmonary diffusing capacity on exercise tolerance. J. Appl. Physiol. 12, 487--491 (1958)

13. Baar, H. S., Galindo, J.: Bronchiolitis fibrosa obliterans. Thorax 21, 209--214 (1966) 14. Becklake, M. R., Goldman, H. I., Bosman, A. R., Freed, C. C.: The long-term effects

of exposure to nitrous fumes. Amer. Rev. Tuberc. 76, 398--409 (1957) 15. Bosomworth, P. P., Hamelberg, W.: Etiologic and therapeutic aspects of aspiration

pneumonitis. Experimental study. Surg. Forum 13, 158--159 (1962) 16. Cameron, J. L., Sebor, J., Anderson, R. P., Zuidema, G. D.: Aspiration pneumonia. Re-

sults of treatment by positive pressure ventilation in dogs. J. Surg. Res. 8, 447--457 (1968)

17. Kapanci, Y., Weibel, E. R., Kaplan, H. P., et al.: Pathogenesis and reversibility of the pulmonary lesions of oxygen toxicity in monkeys. 2. Ultrastructural and morphometric studies. Lab. Invest. 20, 101--118 (1969)

18. Lewinski, A.: Evaluation of methods employed in the treatment of the chemical pneumonitis of aspiration. Anesthesiology 26, 37--44 (1965)

19. Downs, J. B., Chapman, R. L., jr., Modell, J. H., Hood, C. I.: An evaluation of steroid therapy in aspiration pneumonitis. Chest 64, 393 (1973)

Dr. H. Bachofen Pneumologische Abteilung Medizinische Universit~itsklinik Inselspital CH-3010 Bern, Switzerland

recovery from aspiration pneumonitis

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