Pulmonary complications of upper abdominal surgery.
Pulmonary complications encountered in 67 patients undergoing upper abdominal surgery in our unit in one year period are analysed. Pulmonary function tests and their post-operative reduction, as also the risk factors are discussed. Pathophysiology responsible for pulmonary complications is outlined.
Abdominal operations form an important segment for a general surgeon's operating list. Pulmonary complications can and do follow such operations. This is a prospective study to evaluate such complications.
From October 1986 till September 1987, 67 patients underwent upper abdominal surgery under general anaesthesia. Only those patients in whom the incision lay entirely or mainly above the umbilicus are included in this study. A detailed history was obtained with reference to their occupation, smoking habits, the type and quality of the cough and sputum, wheezing, dyspnoea, haemoptysis and pre-existing pulmonary or cardiac disease. Clinical examination was carried out regarding their age, sex, build, height and weight; rate and type of respiration, anaesthesia risks and associated pulmonary and/or cardiac signs. In addition to routine investigations, pre-operative chest X-ray, E.C.G., sputum analysis and antibiotic sensitivity were carried out. The following pulmonary function tests (P. F. Ts) were carried out: (a)' breath holding time, (b) maximum expiratory pressure, (c) tidal volume, (d) inspiratory reserve volume, (c) expiratory reserve volume, (f) residual volume, (g) forced vital capacity, (h) forced expiratory volume (11 second), (i) peak expiratory flow, G) I. M. B. C. and D. M. B. C., (k) mid-expiratory flow rate, and (e) arterial blood gas analysis.
Post-operatively, sedation, supplementary O2, medicated inhalations, and respiratory physiotherapy was given. Bronchodilators, mucolytics and bronchial suction were used when indicated. All patients received appropriate antibiotics. P. F. Ts and chest X-rays were repeated between 8th and 10th post-operative day.
A patient was deemed to have pulmonary complication if he/she had productive cough and pyrexia and showed presence of physical chest signs, which were absent pre-operatively.
Of the 67 patients (44 males and 23 females) studied, 40 underwent a planned procedure whereas 27 required emergency surgery. There were 20 cases in 13-25 year age group, 16 in 26-40 year age group, 26 in 41-55 year age group and 5 in 56-70 year age group. The anaesthetic risk was good in 28, fair in 33 and poor in 6 cases. Associated medical conditions were: chronic bronchitis in 16 cases, pulmonary tuberculosis in 5, cancer cachexia in obstructive jaundice and essential hypertension in 2 cases each, and aspiration pneumonia, pleural effusion, bronchial asthma on bronchodilators, obesity and septicaemia in one case each. The types of surgery employed, is shown in Table 1. The duration of surgery varied from 1 to 3.5 hours.
Post-operative complications are listed in Table 2. There were 6 deaths in our series; 4 occurred during the routine procedure whereas 2 followed emergency operation (Table 3).
The duration of the hospital stay varied from 8 to 45 days (mean = 15.6 days). The infective pulmonary complications were treated with appropriate antibiotics. Those with pleural effusion required thoracocentesis. Tracheostomy was required in 5 cases to facilitate tracheo-bronchial toilet.
In our series of 67 patients, 37 (54.2%) had pulmonary complications forming the single largest cause of morbidity and mortality in the post-operative period ,,,,. In the literature, this incidence varied from 5 to 60% ,,.
Reduction in pulmonary functions has been reported by many workers,,,,,,. Figs. 1 and 2 show a comparison of the observed and predicted values of FVC and FEV1 in male and female patients from our series. Thus it will be seen that even by Indian standards our patients started with lower predicted values, which were further reduced in the post-operative period, the reduction being about 20% even on 8th to 10th day. Reduction percentage in other P. F. Ts are shown in Table 4. Whenever inspiratory reserve volume (IRV), direct maximum breathing capacity (DMBC) and FEV1 were reduced, there were post-operative pulmonary complications.
Effect of planned Vs emergency surgery:
In our series, 15 of the 40 patients (37.5% operated electively developed pulmonary complications as compared to 22 of the 27 patients (81.5%) operated upon as an emergency - a finding similar to that of others,. The possible causes for this may be: (a) poor general condition, (b) no pre-operative assessment of chest condition, (c) vomiting in emergency procedure causing aspiration pneumonia, (d) collection of fluid and/or blood in the peritoneal cavity restricting the diaphragm movements, and (e) massive blood transfusion leading to a bleeding disorder and/or pulmonary oedema.
Factors influencing pulmonary complications:
Old age beyond 50 years increases the incidence of pulmonary complications ,,. The possible explanation for this may be: (a) decrease in static lung volume, (b) diminished MEFR, (c) reduced pulmonary elastic recoil, (d) reduction in PaO2.
Development of pulmonary complications seems to be more in males (61.2%) than in females (30.4%),,, possibly due to smoking habits of men, more dependency of diaphragmatic breathing and bronchial “catarrah”.
Although obesity is a recognised risk factor,, most of our patients belonged to the lower socio-economic strata; hence no firm conclusion could be drawn. Only one patient in our group was obese and developed bronchitis, bronchospasm and wound dehiscence.
Smoking and pre-existing pulmonary disease:
All habitual smokers developed postoperative pulmonary complications. Twenty-four cases had pre-existing pulmonary disease and 16 of these had chronic bronchitis due to smoking and hence the incidence of pulmonary complications in such patients is always high,,,,,. Similarly patients with pulmonary tuberculosis, aspiration pneumonia, achalasia cardia, pleural effusion and those who are poor risk for general anaesthesia, are prone to the development of pulmonary complications.
Associated medical conditions:
Cachexia due to cancer stomach, generalised septicaemia, obstructive jaundice, biliary strictures were found to influence the development of post-operative pulmonary complications.
Duration of surgery:
When the duration of operation was more than 2 hours, 66.6% patients developed complications. As the duration increases, the incidence also increases 2-3 times.
Post-operative pulmonary complications:
The incidence (20-25% following upper abdominal surgery and 5-10% following lower abdominal surgery has changed very little in the past 40 years.
Bronchitis, consolidation, bronchopneumonia, atelectasis also contribute to development of complications but are preventable causes,,. Associated wound infection showed no definite relationship in the development of pulmonary complications,.
Mortality in patients with post-operative pulmonary complications varies from 3 to 10%; in our series it was 5.96%.
In conclusion, based on our study, IRV, FEV1 and DMBC are the PFTs which may influence the selection of patients, may modify the approach of the anaesthetist, and may indicate the need for prophylactic measures pre-operatively and in the early post- operative period.
We thank the Dean, Seth GS Medical College and King Edward Memorial Hospital, Mumbai 400 012, for permission to use the hospital records. We also thank the King Edward Memorial Hospital and Seth GS Medical College Research Society, for giving us a grant for this research study, during 1986-87.