Departments of 'Radiology and JSurgery, University of Iowa Hospitals and Clinics, Iowa City, ... Radiology, Allegheny General Hospital, Pittsburgh, PA 15212,.
1983, The British Journal of Radiology, 56, 531-534
AUGUST
1983
Lobar collapse in the surgical intensive care unit By fJohn E. Shevland, M.B., Ch.B., M.R.A.C.R., *M. T. Hirleman, M.D., *K. A. Hoang, M.D., and JG. P. Kealey, M.D. Departments of 'Radiology and JSurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, U.S.A. (Received February 1983)
ABSTRACT
The chest X rays of 200 consecutive patients in the surgical Intensive Care Unit were reviewed. Eighteen cases of lobar collapse were diagnosed in 17 patients (8.5%) with a high degree of certainty. Most cases involved the left lower lobe (12/18, 66%), but collapse of the right lower lobe (4/18, 22%) and the right upper lobe (2/18, 11%) was also noted. Although theories have been postulated to account for the high incidence of left lower lobe collapse following cardiac surgery, the predominance of left lower lobe collapse generally amongst ICU patients is not fully explained. MATERIALS AND PATIENTS
Over a ten-week period, the chest radiographs of all patients in the Surgical Intensive Care Unit (SICU) were reviewed to assess the incidence and distribution of lobar collapse. Cases excluded from the study were: (a) Collapse, not lobar in character, e.g., linear, subsegmental, and those cases with obvious volume loss in one hemithorax, difficult to localise to, or perhaps involving more than, one lobe. (b) Collapse secondary to a malplaced endotracheal tube. (c) Collapse secondary to a space-occupying process in the pleural cavity, e.g., pneumothorax, haemothorax. A total of 200 patients was included in this study. The diagnostic classification of the subjects is shown in Table I. All patients in the SICU are nursed on Ohio or Bourns Bear 1 ventilators with cascade humidifiers set at 100% humidity. Patient positioning includes postural drainage, side-to-side rolling, vibrators, hyperventilation and suction on a 1 to 2 hour basis as per physical therapy or more frequently as required. Patients are X rayed using a specially designed double-screen cassette, containing two medium-speed films. Using a 70-80 kVp range, a density factor difference of 2 between the two films is routinely obtained. Generally the front film shows better penetration, giving a good view of the retrocardiac area on the left in particular. The double cassette technique has resulted in less than 1% of examinations being fPresent address and address for reprints: Department of Radiology, Allegheny General Hospital, Pittsburgh, PA 15212, USA
repeated for exposure errors (Franji & El-Khoury, 1981). For the purposes of this study, our intention was confined to the distribution patterns of lobar collapse. Obviously such factors as smoking history, presence of acute or chronic lung disease, age, length of anaesthesia, etc., are important factors predisposing to atelectasis, but knowledge or awareness of these would not be universally expected to predict the distribution of the lobar collapse. For similar reasons episodes of concurrent SICU disease such as infection, barotrauma, heart failure, pulmonary infarction and adult respiratory syndrome have not been documented. RESULTS
The distribution pattern of lobar collapse is shown in Table II. Eighteen cases were diagnosed in 17 patients (8.5%). One of the patients, an eight-year-old boy with diabetic keto-acidosis, had collapse of the left lower lobe and right upper lobe at different times. Twelve cases of left lower lobe collapse were documented (66%). The right lower lobe was involved in four cases (22%) and the right upper lobe in two (11%). The lower lobes were involved in 89% of cases. Of the 200 patients in the study (Table I), the status of 124 (62%) was post cardio-thoracic surgery, the majority of these having undergone coronary artery bypass procedures (71/124, 57%). Half of the cases of lobar collapse (9/18) occurred in Group 1 patients (Table HI) although the overall incidence of lobar collapse in this group is less than 10% (Table IV). 6/71 (8.5%) of the coronary artery bypass patients had episodes of lobar collapse. Although 12.5% of all patients had undergone head and neck surgery (Group 2), no episodes of lobar collapse were documented in this group. Group 3 patients represented the post abdominal and pelvic surgical cases. Only one example of lobar collapse occurred in the 24 patients, this being a case of right upper lobe collapse following splenectomy. Eighteen medical patients (Group 4) were admitted to the SICU because of logistic problems: five cases of lobar collapse were documented in this group. This represented 28% of the total number of cases of lobar collapse, and indicated that over one quarter (28%) of the medical group had an episode of lobar collapse. Group 5 patients comprised those admitted with
531
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56, No. 668 John E. Shevland, M. T. Hirleman, K. A. Hoang and G. P. Kealey TABLE I DIAGNOSTIC CLASSIFICATION OF PATIENTS
Group
Diagnosis
1 Cardio-thoracic surgery
Coronary artery bypass Mitral valve replacement Aortic valve replacement Congenital heart disease Double valve replacement Thoracic aortic aneurysm Ventricular aneurysm Miscellaneous Neurosurgical Otolaryngological Upper abdominal surgery Lower abdominal surgery Vascular surgery Miscellaneous Reyes' syndrome Guillain-Barre syndrome Miscellaneous Motor vehicle accidents
2 Head & neck surgery 3 Abdomino-pelvic surgery
4 Medical emergencies 5 Trauma (multiple)
No. of patients
Total
124
25
24
18 9
TABLE II DISTRIBUTION OF LOBAR COLLAPSE
Site
Diagnostic category
Left lower lobe
Cardiothoracic surgery Coronary artery bypass Mitral valve replacement Medical emergencies Reyes' syndrome Herpes encephalitis Diabetic ketoacidosis Multiple trauma Cardiothoracic surgery Coronary artery bypass Multiple trauma Medical emergencies Guillain-Barre syndrome Abdomino-pelvic surgery Splenectomy Medical emergencies Diabetic coma
Right lower lobe
Right upper lobe
No.
multiple trauma secondary to motor vehicle accidents: three of the nine patients (33%) had episodes of lobar collapse. DISCUSSION
Although some studies show a low incidence of atelectasis in ICU patients (Zwillich et al, 1974) it is generally accepted that atelectasis is the most frequently demonstrable infiltrate in the ICU patient (Goodman & Putnam, 1978). Most intensive care and postoperative complication reviews do not include a breakdown of the type of collapse detected radiographically and many in
Total
12
fact do not differentiate collapse from consolidation (Fortham & Shepard, 1969). It is difficult therefore to gauge the incidence of lobar collapse, although most clinicians and radiologists involved in ICU work know it to be quite common. To quote Marini et al (1979), "Acute lobar atelectasis is a frequent problem of critically ill patients, which if left untreated may result in impaired gas exchange, parenchymal infection or eventual fibrosis." The incidence of lobar collapse in the present study was 8.5%. Prior to this study it had been our impression that
532
AUGUST
1983
Lobar collapse in the surgical intensive care unit TABLE III RELATIONSHIP OF NUMBER OF CASES OF LOBAR COLLAPSE PER DIAGNOSTIC GROUPING TO TOTAL NUMBER OF CASES
Group
No. of cases of lobar collapse
% of total
1 2 3 4 5
9 0 1 5 3
50 0 5 28 17 TABLE IV
INCIDENCE OF LOBAR COLLAPSE WITHIN SPECIFIC DIAGNOSTIC GROUPING
Group
No. of cases of No. of patient;> lobar collapse
Incidence of lobar collapse within specific group, %
1 2 3 4 5
124 25 24 18 9
7.3 0 4.2 28 33
9 0 1 5 3
left lower lobe collapse was the commonest form of lobar collapse in the SICU, regardless of the particular diagnostic category of the patient. Two-thirds of our cases of lobar collapse involved the left lower lobe. Of these 58% (7/12) occurred in patients who had undergone cardiac surgery and 42% (5/12) involved the medical and trauma cases. It is, of course, well known that left lower lobe collapse is common following cardiac and upper abdominal surgery (Katzberg et al, 1978; Templeton et al, 1966). It is less well known that the left lower lobe is susceptible to collapse in a host of other ICU conditions. In Marini's series of 31 critically ill patients (Marini et al, 1979), there were 26 episodes of lobar collapse (the remaining five patients had involvement of more than one lobe). Sixteen of these (62%) involved the left lower lobe. Judging from their clinical data it appears that 10 of these 16 cases (62%) occurred in medical and trauma patients, and only 6/16 (38%) involved postoperative thoracic and abdominal patients. The radiological diagnosis of lobar collapse is based on displacement of specific intrathoracic structures (Fraser & Pare, 1977). It is often difficult to differentiate collapse from pneumonia, and in some patients, particularly following cardiac surgery, a pleural effusion adjacent to the mediastinum may simulate left lower lobe collapse (Adams, 1979). Serial films usually resolve the problem. A unique feature of patients on relatively high concentrations of oxygen is the rapidity with which absorption collapse of a lobe may occur.
Absorption collapse of a lobe is commonly attributed to occlusion by a mucus plug, at least in postoperative patients, but bronchoscopy frequently fails to locate the incriminating secretions (Bowen et al, 1974). Postoperative collapse can occur in patients without increased secretions and in patients with normal lungs (Tisi, 1980). Reasons have been advanced to explain left lower lobe collapse following cardiovascular surgery: (a) In the supine position the weight of an enlarged heart may interfere with the aeration of the left lower lobe (Lindholm et al, 1974). (b) With topical cooling of the heart with ice, the left phrenic nerve becomes exposed to prolonged hypothermia, the so-called "frost-bitten phrenic". This leads to paralysis of the left dome of the diaphragm and subsequent collapse involving the adjoining left lower lobe (Benjamin, 1982). (c) Elevation of the diaphragm secondary to gastric distension is a possibility following both cardiac and upper abdominal surgery. This is thought to be an unlikely mechanism in producing collapse, as the presence of an indwelling naso-gastric tube has no effect on the incidence of collapse (Benjamin et al, 1982). Because of the increased incidence of left lower lobe collapse in ICU patients other than those who have undergone cardiac or upper abdominal surgery, additional factors must be at work. It is known that the presence of an endotracheal tube may impair mucociliary clearance and impede effective coughing. Undirected suctioning of the tracheobronchial tree usually results in right lower lobe suctioning. There is a less than one in three chance of entering the left bronchial tree, probably because of the greater angulation of the left bronchial take-off from the trachea (Freedman & Goodman, 1982). An increased incidence of left lower lobe atelectasis might therefore be anticipated. Inappropriate application of a suction tube, however, can cause mucosal damage and suppress mucus clearing. As this would occur more frequently on the right, a build-up of secretions and subsequent collapse of the right lower lobe might be expected. Gamsu et al (1976), in postoperative tantalum insufflation studies, have in fact shown a right lower lobe predominance in the incidence of collapse. Therefore, although it seems likely that the left lower lobe collapses preferentially in the SICU patient, the exact reason or reasons for this remain enigmatic. REFERENCES ADAMS, F. G., 1979. A simplified approach to the reporting of intensive therapy unit chest radiographs. Clinical Radiology, 30, 219-226. BENJAMIN, J. J., CASCADE, P. N., RUBENFIRE, M.,
WAJSZCZUK,
W. & KERIN, N. Z., 1982. Left lower lobe atelectasis and consolidation following cardiac surgery: the effect of topical cooling on the phrenic nerve. Radiology, 142, 11-14.
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BOWEN, T. E., FISHBACK, M. E. & GREEN, D. C ,
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KATZBERG, R. W., WHITEHOUSE, G. H. & DE WEESE, J. A.,
Treatment of refractory atelectasis. Annals of Thoracic Surgery, 18, 584-589. FORTHAM,
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1978. The early radiologic findings in the adult chest after cardiopulmonary bypass. Cardiovascular Radiology, 1, 205-215.
Postoperative
pulmonary complications. Southern Medical Journal, 62, 1198-1200.
LINDHOLM, C. E., OLLMAN, B., SNYDER, J., MILLEN, E. &
GRENVIK, A., 1974. Flexible fiberoptic bronchoscopy in critical care medicine. Critical Care Medicine, 2, 250-261.
FRANJI, S. M. & EL-KHOURY, G. Y., 1981. Applications of
double-screen 59-62.
roentgenography.
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Radiology, 10,
MARINI, J. J., PIERSON, D. J. & HUDSON, L. D., 1979. Acute
FRASER, R. G. & PARE, J. A. P., 1977. Diagnosis of Diseases of
lobar atelectasis—a prospective comparison of fiberoptic bronchoscopy and respiratory therapy. American Review of Respiratory Disease, 119, 971-978.
the Chest (W. B. Saunders, Philadelphia), Vol. 1, Chap. 4. FREEDMAN, A. P. & GOODMAN, L., 1982. Suctioning the left
TEMPLETON, A. W., ALMOND, C. H., SEABER, A., SIMMONS, C.
bronchial tree in the intubated adult. Critical Care Medicine, 10, 43^*5.
& MACKENZIE, J., 1966. Postoperative pulmonary patterns following cardiopulmonary bypass. American Journal of Roentgenology, 96, 1007-1018. TISI, G. M., 1980. Pulmonary Physiology in Clinical Medicine. (Williams & Wilkins, Baltimore), Chap. 7.
GAMSU, G., SINGER, M. M., VINCENT, H. H., BERRY, S. &
NADEL, J. A., 1976. Postoperative impairment of mucus transport in the lung. American Review of Respiratory Disease, 114, 673-679. GOODMAN, L. R. & PUTNAM, C. E., (EDS), 1978. Intensive Care
ZWILLICH, C. W., PIERSON, D. J., CREATH, C. E., SUTTON, F. D., SCHATZ, E. & PETTY, T. L., 1974. Complications of
Radiology: Imaging of the Critically III (Mosby, St. Louis) Chap. 4.
assisted ventilation—a prospective study of 354 consecutive episodes. American Journal of Medicine, 57, 161-170.
Book review Radionuclide Ventricular Function Studies. By P. J. Ell, S. Walton and P. H. Jarritt, pp. x+172, 1982 (Martinus Nijhoff The Hague/Boston/London), D.fl. 250.00 $99.50. ISBN 90-247-2639-5 The full range of radioisotope techniques for cardiac study is briefly reviewed but the book is particularly concerned with radionuclide ventriculography using both first pass and equilibrium (gated blood pool) techniques, both at rest and during exercise. The introductory section gives a good overview of the current status of this subject and would be useful to anyone becoming involved in this field. The second chapter is concerned with instrumentation and becomes rather involved with details of data acquisition. It is most suitable for those who are particularly involved in the development and practical operation of the equipment. The explanations in this section are rather complicated and would be fully appreciated only by those who understand the subject well already. The most interesting and the largest section of this book is
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an atlas of clinical cases. In this section 50 clinical cases are reviewed and colour images of isotope studies are included for each patient. Coloured images of amplitude and phase analysis are also included for each patient and this will certainly stimulate the reader to consider the potential value of these new computer assisted techniques. The interpretation of the images is explained rather briefly in each case and I suspect that in reality the interpretation is less straightforward than the book might suggest. There are useful short sections at the end which discuss advantages and disadvantages of various investigational techniques for studying the left ventricle and a short glimpse into the future is offered as a conclusion. This is an interesting small book which offers a useful colour atlas. It is not the definitive volume on the subject but it would be a useful addition to any department where routine radionuclide ventriculography was being performed. PETER WILDE.
