Complications after emergency tube thoracostomy: assessment with CT.
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Biomedical subjects
Publications and source records attributed to L R Goodman.
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CT has brought new insights into our understanding of the patient with acute respiratory distress, pulmonary edema, and adult respiratory distress syndrome. This article documents some of the physiologic and imaging information gained from axial imaging of the critically ill.
PURPOSE: To investigate the feasibility of imaging diaphragmatic motion with a fast gradient-recalled-echo (GRE) magnetic resonance (MR) pulse sequence. MATERIALS AND METHODS: Fast GRE pulse sequences in sagittal and coronal planes were used to acquire repeated, single-level, 1.2-second scans in 10 healthy volunteers during deliberately slowed, approximate-vital-capacity breathing. Motion was analyzed subjectively by viewing the image sequences as cine loops and quantitatively by measuring the displacement of different points on the diaphragm at a workstation. RESULTS: Temporal and spatial resolutions were adequate in all subjects. Absolute excursion of the domes was 4.4 cm on the right and 4.2 cm on the left. Analysis of diaphragmatic displacement at different locations revealed a gradient of excursion that increased from anterior to middle to posterior (P < .05-.001; paired t test). Excursion of the lateral aspects was greater than that of the medial aspect (P < .001). CONCLUSION: Fast GRE MR imaging can be reliably used to demonstrate diaphragmatic motion and may prove useful in the investigation of normal and abnormal respiratory mechanics.
OBJECTIVE: This study was designed to prospectively compare helical CT with pulmonary angiography in the detection of pulmonary embolism in patients with an unresolved clinical and scintigraphic diagnosis. SUBJECTS AND METHODS: Twenty patients with an unresolved suspicion of pulmonary embolism were evaluated with contrast-enhanced helical CT and with selective pulmonary angiography. An average of 11 hr separated the two studies. The CT scans were obtained during one 24-sec or two 12-sec breath-holds. CT scans were interpreted without knowledge of the results of scintigraphy or angiography. Selective pulmonary angiograms were obtained with knowledge of the findings on the ventilation/perfusion scan only. The sensitivity and specificity of CT were compared with those of angiography for central vessels (segmental and larger) only and for all vessels. RESULTS: Eleven of the 20 patients had proved pulmonary embolism (seven in central vessels and four in subsegmental vessels only). When only central vessels were analyzed, CT sensitivity was 86%, specificity was 92%, and the likelihood ratio was 10.7. However, when subsegmental vessels were included, CT results were 63%, 89%, and 5.7, respectively. CONCLUSION: In our subset of patients, helical CT was only 63% sensitive. Subsegmental emboli are difficult to diagnose. Pulmonary angiography remains the study of choice. CT has a limited role in the evaluation of acute pulmonary embolism.
OBJECTIVE: The purpose of this study was to determine how often chest tubes placed for acute trauma lie within a pleural fissure and to determine whether an intrapleural location influences outcome. SUBJECTS AND METHODS: Fifty-eight consecutive thoracostomy patients who had 66 chest tubes were studied prospectively. Tube location was determined from frontal and lateral chest radiographs. Outcome measures recorded included the following: duration of thoracostomy drainage, quantity of pleural fluid drained, need for further tubes, length of hospital stay, appearance on last chest radiograph before discharge, and need for surgical intervention. RESULTS: Thirty-eight (58%) of the tubes were placed within a pulmonary fissure, 15 (23%) were posterior, nine (13%) were anterior, and four (6%) were in other locations. We found no significant difference in any of the outcome measures between tubes located in the fissure and other tubes. CONCLUSION: A large percentage of tubes placed for acute chest trauma lie within a pleural fissure. These tubes, however, appear to function as effectively as those located elsewhere in the pleural space.
To evaluate the value of decubitus chest radiography in the clinical assessment of pneumothorax, the authors compared the detectability of pneumothorax on expiratory, upright chest radiographs with that on expiratory, lateral decubitus radiographs obtained with the suspected side up. Five radiologists reviewed 19 sets of radiographs with pneumothoraces and 20 sets of radiographs without pneumothoraces. All five radiologists were more accurate and had greater confidence in the evaluation of the upright studies. A pneumothorax was detected 21% (77 versus 57 of 95) more often on the erect radiographs. In three cases, however, decubitus positioning was more definitive. These results suggest that when clinically feasible, the expiratory, upright chest radiograph is the procedure of choice for the evaluation of small pneumothoraces.
Computed Equalization Radiography (CER) was designed to increase visualization of mediastinal structures without affecting lung contrast. CER optimizes the image by obtaining two 1-second fan beam scans. The initial low-dose prescan determines the location of the lungs by means of a stationary krypton gas detector. During the equalization scan, this information is used to position 35 beam attenuators in real time so as to increase exposure of the mediastinum while maintaining ideal optical density over the lungs. Eight observers analyzed 20 pairs of posteroanterior (PA) and lateral radiographs obtained on conventional and CER units. On the PA images, three of four mediastinal areas analyzed were visualized better in CER images, while there was no difference in lung detail. There were no appreciable differences in the lateral projection between the CER and conventional images. Contrast on the PA radiograph was preferred on the CER image. CER provided modest improvement in visualization of mediastinal structures and maintained lung contrast without degrading lung detail on the PA image. CER had no major effect on visualization in the lateral images.
Acute mediastinitis and sternal infection after sternotomy are potentially devastating complications, but considerable advances in treatment have been made during the past decade. Sternectomy followed by reconstruction with use of either an omental transposition or a muscle flap has markedly decreased mortality and morbidity. After extensive rib resection, various reconstructive repairs, including the use of polytetrafluoroethylene mesh, have proved successful. The authors retrospectively reviewed 27 postoperative computed tomographic (CT) scans obtained in 19 patients. Twelve of these patients had sternal wounds repaired with either omental or muscle flap procedures. Seven patients had chest wall reconstructions with polytetrafluoroethylene patches, muscle transpositions, or both. The authors found no cases of unexpected or unexplained fluid collections on CT scans obtained beyond the 1st month. Any persistent or recurrent collection is suggestive of infection. If clinical and imaging findings are at odds, imaging-directed needle aspiration can help determine whether a fluid collection is infected and in need of further treatment.
The low positive yield from aortography in patients with suspected traumatic aortic rupture has prompted research into CT of the mediastinum as a screening investigation which could significantly reduce the number of negative angiograms performed. Much of the data published to date suggest a promising role for CT, but false negative scans have been reported and the precise false negative rate has yet to be determined. We propose an algorithm for the use of CT in suspected traumatic rupture but emphasise that continuous monitoring of outcomes and further large studies are required before CT can become an established screening technique.
To investigate the value of 5-mm contrast material-enhanced computed tomography (CT) in patients with moderate to low probability of aortic laceration after a substantial deceleration injury, scans were obtained through the upper mediastinum in 160 consecutive patients. Thoracic angiography and aortography were performed in patients with evidence of mediastinal hemorrhage at CT. There was no evidence of mediastinal hemorrhage in 132 patients with normal admission chest radiographs. In the 28 patients with abnormal admission chest radiographs, CT helped exclude mediastinal hemorrhage in 22 patients (78%), and 19 patients (68%) were treated without undergoing angiography. Six patients had mediastinal hematoma at CT. Only one had an aortic laceration at angiography. The authors conclude that 5-mm contrast-enhanced CT can help exclude mediastinal hemorrhage and reduce the angiography rate in low-to-moderate-risk patients with a widened or indeterminate mediastinum. There were no unsuspected cases of mediastinal hemorrhage in patients with normal chest radiographs. Angiography is recommended for patients considered to be at high risk for aortic laceration.
To evaluate the effects of scanning equalization radiography (SER) on the detection of diffuse lung disease a clinical comparison between an Advanced Multiple Beam Equalization Radiography (AMBER) unit and conventional chest radiography was performed. Even though the overall detection of focal pulmonary lesions with the AMBER unit has been shown to be significantly higher than with conventional radiography because of the improved demonstration of the costophrenic and retrocardiac regions, the utility of AMBER in the demonstration of diffuse lung disease has not been established. Twenty-one patients with diffuse lung disease (fibrosing alveolitis or sarcoidosis) and six patients with no pulmonary disease had high kVp frontal and lateral chest radiographs on both an AMBER unit and a conventional chest stand. The pooled results of five observers using Receiver Operating Characteristic (ROC) analysis indicate that there is a slight improvement but no statistically significant difference in observer performance between AMBER (Area under the ROC curve AZ = 0.934) and conventional radiography (AZ = 0.868) in the task of detecting diffuse lung disease.
The pathophysiology and radiographic appearances of hydrostatic and increased permeability pulmonary edema are presented. Both typical and atypical appearances are discussed. The ability of the plain chest radiograph to differentiate between different types of edema is examined.
Prototype electronic workstations incorporated in networks linking computed tomographic (CT) and magnetic resonance imaging systems are being developed. The authors compared observer efficiency and sensitivity in reading body CT studies from a two-screen workstation (1,000-line monitors and 12-bit dynamic range in image memory) and conventional film panel alternator. The two-screen workstation displayed 32 images at a matrix resolution of 256 x 256 or eight images at a matrix resolution of 512 x 512 simultaneously. Ninety-six images with a matrix resolution of 512 x 512 could be displayed simultaneously at the film panel alternator. Four observers read images from 20 cases, 10 with repeat examinations, in a randomized viewing sequence. There was an average of 32 images per case. Reporting time was less with the film panel alternator (average, 5.08 minutes) than with the workstation (average, 6.66 minutes). There was improved sensitivity for all observers in reading from the film panel alternator (range, 1%-12%) (P less than .05). In complex cases evaluated by means of body CT, the current prototype two-screen electronic workstation is limited by display capabilities.
After blunt abdominal trauma, the spleen often increases in volume on serial computed tomographic (CT) scans. To determine the frequency and significance of such enlargement, the authors performed a retrospective analysis of 44 hemodynamically stable patients who had experienced recent blunt abdominal trauma. The severity of splenic, hepatic, or other visceral injuries seen on each CT scan was numerically scored, and the amount of intraperitoneal fluid was assessed. Twenty-five patients (57%) had over 10% enlargement (average enlargement, 56%) on follow-up scans. Increasing volume did not correlate with clinical deterioration or the need for splenectomy. It did correlate modestly with the amount of blood in the peritoneum on CT scans, the number of units of blood transfused, and two clinical indexes of systemic trauma. Therefore, an enlarging spleen is not a CT indicator of a deteriorating clinical condition. This phenomenon is most likely due to marked adrenergic stimulation after injury and changing fluid volumes.
Implantable central venous access devices placed via the subclavian vein may become obstructed by thrombosis, impingement against a vein wall, or compression between the clavicle and first rib. The latter has been termed pinch-off syndrome (POS). Eleven patients with POS were studied, including one whose catheter had fractured and one whose catheter had fragmented. They were compared with 22 matched control patients and 100 consecutive routine clinic patients. Each catheter was graded: 0 = normal, 1 = abrupt change in course with no luminal narrowing, 2 = luminal narrowing, and 3 = complete catheter fracture. POS was present in most (eight of 11) cases within 3 weeks after placement. A grade 1 catheter was common (33%) among control subjects, but grades 2 and 3 were uncommon (1%). Catheter fracture or fragmentation was seen in two of five cases with long-term (greater than 3 weeks) pinching (grade 2 catheter). The following conclusions were reached: Grade 2 represents significant catheter compression and the potential for serious complications. Grade 1 is of uncertain clinical significance, due to its high prevalence in control subjects.
Allergic bronchopulmonary aspergillosis (ABPA) is a destructive disease of the lung characteristically associated with central bronchiectasis. This study was designed to determine if high-resolution computerized tomography (CT) could be used to define bronchiectasis in patients with suspected disease. Sixteen patients with asthma were studied. All demonstrated immediate cutaneous reactivity to common aeroallergens including Aspergillus fumigatus. Eight patients had clinical and immunologic evidence of ABPA. Six to 12 high-resolution CT sections (1.5 mm) were obtained at 1- to 2-cm intervals from the aortic knob to the dome of the diaphragm. All radiographs were evaluated separately by two readers in a blinded fashion and graded as to the presence and type of bronchial dilatation and bronchial wall thickening. Bronchial dilatation was seen in 41% of lung lobes in the ABPA group compared to 15% in the non-ABPA asthmatic control group. Upper lobe involvement and bronchial wall thickening was common to both groups. The presence of bronchiectasis in the control group may indicate that asthma is a more destructive lung disease than is currently appreciated. High-resolution CT of the chest has been shown in previous studies to have a sensitivity and specificity approaching that of bronchography, and the current findings support its use in the detection of bronchiectasis in patients with asthma suspected of having ABPA.
Automatic implantable cardioverter defibrillators (AICDs) were studied in three groups: (a) Serial radiographs were reviewed in 51 clinic patients. Twenty of 96 (21%) AICD patches distorted with time. (b) Thirty-six postoperative computed tomographic (CT) scans of asymptomatic patients revealed that pericardial fluid collections were frequent during the month after surgery but rare beyond that. Echocardiography was insensitive for these collections. CT also demonstrated dense fibrosis around some distorted patches, months after surgery. (c) Five other patients with pericardial infection had distorted patches, and the four studied with CT had fluid beneath their patches. (d) A case of constrictive pericarditis had distorted patches but was not diagnosed with CT. The authors conclude that distorted patches may indicate postoperative complications and that CT is the imaging modality of choice.