Portable Chest Roentgenography and Computed Tomography in Critically III Patients

Portable Chest Roentgenography and Computed Tomography in Critically III Patients* William

Peruzzi,

M . D . , t Warren

Jukka Rasanen, M.D.;$ and Thomas Reilley,

Charles

Garner,

M.D.;% John Booh,

M.D.;§

F. Mueller, M.D.;\\

D.OM

Computed tomography ( C T ) of the chest offers improved

of significant intrathoracic pathologic conditions which have

resolution and sensitivity for evaluating chest pathologic

been significantly underestimated by portable chest roent-

conditions compared with other imaging techniques. Inten-

genography. W e discuss the reasons for this improved

sive care unit patients with portable chest findings that

detectability by CT, as well as suggest alternative techniques

diverge from the clinical course may actually have severe

that can be performed at the bedside in patients whose

intrathoracic disease that can be detected with CT. O u r

initial portable chest roentgenogram and clinical course do

three patients demonstrate chest C T can aid in the diagnosis

not correlate.

r

I ""he portable chest roentgenogram is one of the ••• most frequent and effective diagnostic examina-

tions used in the intensive care unit.

1

It is easily

obtained and frequently demonstrates most pathologic conditions, but does have shortcomings. Because a significant portion of the lower lobes lie below the diaphragmatic domes,

pathologic

findings

in these

areas may be obscured or unidentifiable on the portable chest r o e n t g e n o g r a m .

U n d e r these circum-

stances, more sophisticated imaging techniques, including computed tomography (CT), may be required

portable decubitus films were obtained in these patients, although these techniques have been described as effective for delineating pneumothorax, pleural effusions, and to more clearly demonstrate the lung bases on the "up" side. These techniques have the advantage of not requiring these severely ill patients to be moved from the ICU to the CT suite. However, they also have the disadvantage of difficulty in producing adequate quality films with reproducibility and difficulties in positioning patients. When the patients were moved to the CT suite for chest examination, these were performed on commercial scanners. The roentgenographic technique factors were 120 KVP 100 mAs, and 2 s scans. Mechanical ventilatory assistance or manual ventilation of the intubated patients were provided during the CT exams.

to clearly define the extent of the disease process. This

CASE REPORTS

report presents three instances in which the portable chest roentgenogram, while far from normal, fails to

CASE 1

demonstrate the full extent of chest pathologic condi-

A 38-year-old morbidly obese woman underwent a subtotal small bowel resection at her local hospital for intestinal infarction due to polyarteritis nodosa. She subsequently developed sepsis and pulmonary insufficiency and was transferred to our hospital. After hemodynamic stabilization, a laparotomy, with near-total small bowel resection and drainage of intra-abdominal abscesses, was performed. Postoperatively, she developed pulmonary, renal, and hepatic failure with an accompanying encephalopathy Cultures of sputum grew Pseudomonas sp. A right pneumothorax developed and was treated with tube thoracostomy. She then developed and was treated with tube thoracostomy. She then developed a pulmonary embolism and protracted respiratory failure. The portable chest roentgenogram demonstrated the right chest tube, right pleural thickening, and two thin walled cystic structures in the right perihilar and suprahilar areas. The left lung appeared normal (Fig 1). We felt that the patient's rapidly deteriorating clinical status warranted an immediate CT for further evaluation of the cavitary disease. In the right hemithorax, the CT (Fig 2) demonstrated a loculated, thick-walled, anterolateral pneumothorax; multiple cavities, none demonstrating air fluid levels; and a possible bronchopleuralfistula.A thoracostomy tube injection (Fig 3) confirmed the presence of the bronchopleural fistula and demonstrated its origin from the axillary subsegmental bronchus of the right upper lobe. Because of the CT findings, antibiotic therapy was changed, chest tubes were repositioned to facilitate evacuation of the pneumothroax, and over the next week,

tions accounting for a significant proportion of the patients overall clinical condition.

MATERIALS A N D METHODS The portable roentgenographic images were made at a distance of 60 inches utilizing techniques which ensured reproducibility of the roentgenograms, insofar as the patients' conditions would permit. When possible, the AP films were obtained with the patient leaning about 10 degrees forward of the true upright position to better reveal the lung bases. Those patients on ventilators had the exposures obtained during maximal inspiration. Exposure techniques were usually at 80 Kv and 6 mAs with exposure times maintained as short as possible to decrease motion artifacts. Neither portable lateral nor *From the Departments of Anesthesiology, Radiology, and Surgery, The Ohio State University College of Medicine, Columbus. tResident in Anesthesiology. ^Critical Care Fellow §Former Resident in Radiology, currently in private practice. ||Professor of Radiology. ^Associate Professor of Anesthesiology and Surgery. Manuscript received March 2; revision accepted October 20. Reprint requests: Dr. Reilley, Ohio State University Hospital, Department of Anesthesiology, Columbus 43210 722

Portable Chest Roentgenography in Critically III (Peruzzi

et al)

FIGURE 1, Case 1. The right thoracostomy tube, the right pleural thickening (arrowheads), and the two perihilar cystic lucencies on the right are demonstrated. None of the traditional signs of penumothorax is seen. her pulmonary status improved significantly. One month later, she was discharged to her home, improved but with continued total parenteral nutrition.

FIGURE 3, Case 1. Thoracostomy tube injection (open arrow) demonstrates contrast freely entering the axillary subsegmental bronchus of the right upper lobe, then draining centrally to the right upper lobe bronchus. CASE 2

A 68-year-old woman had previously undergone multiple surgical procedures for peptic ulcer disease. She developed a recurrent upper gastrointestinal hemorrhage and underwent laparotomy at a local hospital. When this procedure did not reveal the source of bleeding, the patient was transferred to our hospital in hypovolemic shock. A left thoracotomy was performed, and the aorta was crossclamped for control of hemorrhage. Laparotomy revealed a bleeding gastroesophageal ulcer. The ulcer was oversewn, and the patient was taken to the ICU. A week after the operation, the

FIGURE 2, Case 1. Upper, CT at the level of carina at lung window demonstrates the axillary subsegmental bronchus (white arrow) just shy of the pneumothorax. The two small prehilar right sided cystic lucencies communicating with the anterior segmental bronchus of the right upper lobe are cavitary lesions (arrowheads). Lower, 1 cm below the carina at lung window More of the larger of these two perihilar cystic lucencies can be seen (black arrowhead) in direct communication with the anterior segmental bronchus of the right upper lobe. Subpleural bronchiectasis of the right upper lobe is also seen.

FIGURE 4, Case 2. A P chest roentgenogram done supine demonstrates a globular heart, left pleural effusion (arrowheads) and atelectasis in the left lower lobe.

CHEST / 93 / 4 / APRIL, 1988

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FIGURE 6, Case 3. Portable supine AP roentgenogram demonstrates opacity of the lower half of the right hemithorax, preservation of the right heart margin, ill defined right perihilar haze with central lucency, and areas of patchy consolidation in the left lung. normal. The patient was receiving actinomycin-D, 0.5 and 1.0 g on alternative days. On the day of admission, the patient required tracheal intubation, mechanical ventilation with 12 cmH 0 positive end-expiration pressure (PEEP), and 50 percent oxygen. The portable supine chest roentgenogram (Fig 6) demonstrated right lower lobe atelectasis and right pleural effusion, slight cardiomegaly, and perihilar haze. Chest physical therapy was performed in an attempt to reinflate the right lower lobe atelectasis. The subsequent day's portable chest roentgenogram (Fig 7) showed worsening of the consolidative pattern in the left lung with little change on the right; hence, a chest CT to further evaluate the status of the underlying lung was performed. Chest CT (Fig 8) demonstrated posterior lung abscesses with cavitation below the dome of the diaphragm on the right. The disease on the left was unsuspected and may have been precipitated or exacerbated by the chest physical therapy. An antibiotic-resistant strain of Pseudomonas aeruginosa was cultured from a tracheal aspirate. The administration of appropriate antimicrobial therapy was associated with slow recovery and discharge from the hospital three months after admission to the ICU. 2

FIGURE 5, Case 2. Upper, CT a lung window demonstrates a pneumothorax (curved arrow) and basically no aerated lung behind the plane of the left main bronchus. A loculated pleural effusion and compensatory lower lobe atelectasis are present posteriorly. Lower, CT at mediastinal window at the level of the left atrium demonstrates the pericardial fluid (white arrow) and an air fluid level (white arrowhead) loculated in the left pleural space inferiorly associated with left lower lobe atelectasis (black arrow). patient developed signs of peritonitis and sepsis. An abdominal C T documented extravasation of gastrointestinal contrast, thus supporting the clinical diagnosis of colonic perforation. After colostomy and drainage, the patient was transiently stabilized, but later deteriorated. Abdominal CT, routine cultures, and multiple portable chest roentgenograms were nondiagnostic. The interpretation of the initial portable chest x-ray film, performed with the patient supine because of the recent surgery, demonstrated a globular heart, apparently a sizeable left pleural effusion, left lower lobe atelectasis, and a left basal thoracostomy tube (Fig 4). Again, variance between the clinical course and the patients roentgenogram, plus nondraining left thoracostomy tube, suggested compartmentalization of fluid or empyema, and a chest CT was obtained. The chest CT confirmed a sizeable pericardial effusion, as well as left sided pneumothorax, an empyema cavity in the left pleural space, and unsuspected atelectasis in the right lobe. Compensatory left lower lobe collapse was also present (Fig 5). The fluid collections were drained with appropriately placed thoracostomy tubes. The patient developed multisystem failure due to sepsis and died three weeks later. CASE 3

A 46-year-old obese white man was admitted to the ICU because of respiratory failure and sepsis which developed after a para-aortic lymphadenectomy for embryonal carcinoma of the right testicle. An orchiectomy had been performed three weeks earlier without complications. At that time results of the chest roentgenogram, the chest and abdominal CT scans, and the lymphographie study were 724

FIGURE 7, Case 3. This AP semi-erect portable chest roentgenogram following physiotherapy demonstrates increase in the left multifocal consolidative areas and persistent obliteration of the right lower hemithorax. Portable Chest Roentgenography in Critically III (Peruzzi

et al)

outlines may be obscured, yielding a "pseudosilhouette sign," and may lead one to falsely suspect the presence of an abnormality The decubitus bedside technique for I C U chest roentgenography can be quite helpful in evaluating the "upside" for the presence and degree of pneumothorax. If the pneumothorax is loculated anteriorly or posteriorly, the decubitus roentgenogram can be obtained with the patient rotated either posteriorly or anteriorly to demonstrate this loculation. Decubitus roentgenography of the upside may also demonstrate better aeration of the lung base as the up diaphragm descends maximally. The decubitus roentgenogram for the downside frequently requires higher technique and is best accomplished with the central ray positioned two to three inches towards the side which is dependent; in this way, free dependent pleural effusions may flow out of the field of the lower lobe uncovering more pathologic findings (ie, a cavity with a fluid level) in the previously opaque lung base. W h e n possible, it is advisable to obtain decubitus views with each side down for their complementary value. 9

FIGURE 8, Case 3. This CT at the dome of the right hemidiaphragm demonstrates two large lung abscesses on the right and an elevated anterior portion of the right hemidiaphragm. Left lower lobe consolidation is also identified posteriorly (arrow).

DISCUSSION

Portable chest roentgenograms are used regularly to provide useful information about chest pathologic findings in critically ill patients. - However, several different types of pathologic conditions are commonly missed on the portable chest roentgenogram. A pneumothorax can be very difficult to identify on supine A P x-ray films because the air may disperse widely throughout the pleural space instead of forming focal collections. Although the use of upright positioning can lessen this problem, complete upright positioning is frequently impossible. As is shown in this and earlier reports, the pneumothorax may be loculated within or behind roentgenographically dense structures, making detection with a portable chest roentgenogram very difficult. Often, the only sign of penumothorax on the supine portable chest roentgenogram is the failure to silhouette a mediastinal structure because of air trapped between the mediastinum and other lung pathologic findings. Pleural effusion also can present a diagnostic dilemma, since it may be difficult to detect the presence of fluid and to differentiate between pleural effusion and posterior-basal atelectasis. It also may be difficult to quantify the amount of fluid present, since it may redistribute in the pleural cavity and appear merely as a thickened pleural space, a thickened major and/or minor fissure, or simply as a uniform increase in the density of the entire lung field. 1

2

34

57

8

9

The technique used to produce the portable chest roentgenogram profoundly influences resulting information. Patient position, inspiratory effort, and degree of penetration can vary widely and cause significant confusion. False abnormalities can occur if the x-ray beam is not directed tangentially toward a given structure (eg, diaphragm). In this situation, 10

The portable lateral film, like the decubitus films, are not often obtained in the ICUs but can better delineate the costophrenic sulci and the frequently obscured lower lobes to advantage. The lateral film is particularly useful when only one lower lobe is involved since the normal lung can provide a window to the opposite lung without the confusion of laterality Both the decubitus and the lateral films can significantly increase the awareness of basal lung disease, unsuspected on the portable A P films. Computed tomography generally is recognized as providing increased resolution compared with more conventional roentgenographic techniques. It is employed routinely to evaluate pulmonary nodules, mediastinal adenopathy, chronic lung disease, and to g u i d e d i a g n o s t i c p r o c e d u r e s (eg, n e e d l e biopsy). Abdominal C T can be used effectively to diagnose postoperative abscesses in patients showing slow clinical improvement or deterioration in their overall condition. Also, lower thoracic CT, during or after abdominal CT, has been found to be very useful in the diagnosis of occult pneumothorax after blunt head or abdominal t r a u m a . While the efficacy of the portable chest roentgenogram has been studied extensively, less attention has been given to the value of chest C T in the evaluation of critically ill patients. Selected patients with multisystem trauma who had chest C T were significantly benefitted 70 percent of the time by the discovery of additional diagnostic information affecting management and outcome in a recent series. 1117

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An important factor in the management of our three patients was the diagnosis of persistent intrathoracic disease which did not seem to respond to appropriate CHEST / 93 / 4 / APRIL, 1988

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therapy In each case, a thoracic C T was performed in order to a define pathologic condition that was not evident on the conventional portable chest roentgenogram. Numerous portable chest x-ray films led us to underestimate the extent of the chest abnormalities in all three cases. Computed tomography revealed several unsuspected intrathoracic abscesses, occult pneumothoraces, and a bronchopleural fistula. With correct diagnoses, inappropriate therapy was discontinued, and appropriate therapy was implemented. Although moving a critically ill patient from the I C U to the C T scanner is a potentially dangerous process, the diagnostic advantage of a chest C T often justifies the risk. W e recommend that chest C T be considered for patients with intrathoracic pathologic

condition

under the following conditions: (1) when the clinical course does not correlate with the current diagnostic examinations, particularly the portable chest roentgenogram, and (2) when the patient is sufficiently stable to tolerate transportation to the diagnostic facility REFERENCES 1 Goodman LR. The post-thoracotomy radiograph. In: Goodman LR, Putnam CE, eds. Intensive care radiology: imaging of the critically ill. Philadelphia: WB Saunders Co, 1983:124-40 2 Bercmeyer WB, Crapo RO, Calhoon S, Cannon CY, Clayton PD. Efficacy of chest radiography in a respiratory intensive care unti: a prospective study Chest 1985; 88:691-96 3 Moore AV, Putnam CE, Raven CE. Acute thoracic trauma. In: Goodman LR, Putnam CE, eds. Intensive care radiology: imaging of the critically ill. Philadelphia: WB Saunders Co, 1983:141-53

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Portable Chest Roentgenography in Critically III (Peruzzi

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