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Biomedical subjects

I Tocino

Publications and source records attributed to I Tocino.

13 recordsLinked to original sources

Chest radiography: a tool for the audit of report quality.

In a radiology department, clinical audit implies multiple readings of selected images to identify those findings that should be recognized and to document any departure from this standard for each radiologist. The authors developed an alternate approach for an audit on the basis of clinical outcomes collected in a medical computing facility. Techniques borrowed from information theory were used to measure the clinical information contributed by radiologists as they interpreted chest radiographs. The reported findings were evaluated in light of the discharge diagnosis. The scores generated quantified the information contributed to the final diagnosis by the radiologist's description. This audit approach was tested in a group of 100 chest radiographs. Significant differences were found in the mean scores for information contributed by five different readers. These differences were similar to differences demonstrated in audits by means of multiple readings of chest radiographs. These results support use of a form of audit that is substantially less expensive and time consuming than that typically used in radiology departments.

Expert Systems

Effectiveness of the kinetic treatment table for preventing and treating pulmonary complications in severely head-injured patients.

The efficacy of using the Kinetic Treatment Table (KTT) to prevent or reduce pulmonary complications in severely head-injured patients is unclear. This study is a prospective, randomized trial using the KTT vs. conventional bed care in severely head-injured patients. Outcome measures were hospital length of stay (LOS), mortality, CNS morbidity at hospital discharge, and rate of improvement of pulmonary status as gauged by chest radiograph, arterial/alveolar PO2 ratio, patient temperature, WBC count, suctioning frequency, sputum volume, and days on ventilator. The KTT group (n = 23) and conventional bed care group (n = 26) were well matched for age, sex, severity of injury, and pulmonary status. There was no significant difference in mortality, CNS morbidity, LOS in ICU or hospital, or rate of pulmonary improvement between the groups. The efficacy of the KTT in reducing pulmonary complications in head-injured patients remains unclear.

Acute Disease

A decision-driven system to collect the patient history.

We have developed a computer-administered history designed to directly interview hospitalized patients with pulmonary disease. A frame-based decision system is used to direct the history and to generate a one- to five-member differential diagnostic list based on this history. This system incorporates a cognitive model of question selection and a Bayesian scoring algorithm. Structures to control the choice of questions are embedded in the diagnostic frames and in a QUERY program that makes the final choice of questions. We have compared the behavior of this decision-driven approach with a history taken using a paper questionnaire. The paper-based history presents 182 questions to every patient and captured 75% of 85 pulmonary diseases in its differential lists. The decision-driven system asks 50.7 +/- 31.0 (mean +/- standard deviation) and captured 74% of 61 pulmonary diseases. Our experience suggests that the use of a computerized diagnostic knowledge base to direct the selection of pertinent questions can substantially reduce the number of questions necessary to collect a diagnostically useful patient history.

Artificial Intelligence

Computed tomography in blunt chest trauma.

While most injuries to the chest can be diagnosed by a portable supine radiograph, computed tomography (CT) adds significant findings that will influence patient management. In addition to requested CT chest examinations, we routinely obtain a limited chest CT during the initial work-up of traumatized patients referred to our radiology department for other CT examinations. The major categories of new information provided by CT are: occult pneumothorax, malpositon of chest tubes, inadequately drained pleural collections, differentiating between posttraumatic abscess and empyema, noninvasive diagnosis of tracheal rupture, and cause of mediastinal widening.

Aorta

Early radiographic signs of tracheal rupture.

Early diagnosis and repair of tracheal rupture are necessary to prevent acute tension pneumothorax, airway obstruction, and chronic tracheal stenosis. Few reliable radiographic signs of tracheal rupture have been proposed. We diagnosed seven cases of tracheal rupture, two related to blunt trauma and five resulting from tracheal intubation. Early radiographic signs included orientation of the distal portion of the endotracheal tube to the right relative to the lumen of the trachea with an overdistended endotracheal balloon cuff, migration of the balloon toward the endotracheal tube tip, and pneumomediastinum and subcutaneous emphysema. In four cases, the overdistended balloon with distal migration preceded the pneumomediastinum by several hours. An overdistended balloon in a patient after tracheal intubation or blunt chest trauma should suggest tracheal rupture.

Adult

Large airway size, lung size, and maximal expiratory flow in healthy nonsmokers.

It has been postulated that airway size and lung size may be dissociated because of developmental differences between the tracheobronchial tree and the pulmonary parenchyma (dysanapsis). To test this hypothesis, we compared measurements of airway size (diameters, cross-sectional area, length and volume of the trachea, diameter and cross-sectional area of the mainstem bronchi) and lung size (total lung capacity, thoracic diameters, lung length), as determined from plain chest radiographs in 79 male and 86 female healthy nonsmokers. In both groups of subjects, the correlation between indexes of airway size and lung size was low. Airway size was not significantly different between men and women, when standardized for lung size. Tracheal diameter and length tended to increase with age. To assess the value of airway size measurements in the prediction of maximal expiratory flow, we compared tracheal and bronchial size with FVC, FEV 0.5, FEV1, and mean forced expiratory flow during the middle half of VC. The correlation between airway size and spirometric indexes was very low. Multiple regression analysis showed that the use of airway size variables in addition to the age and height variables did not substantially improve the prediction of maximal expiratory flow. Our results are consistent with the dysanapsis hypothesis, but they suggest that the introduction of radiologic estimates of large airway size in the prediction equations relating maximal expiratory flow to age and height is not justified, at least in the general population.

Female

Positive end-expiratory pressure following coronary artery bypass grafting.

Pulmonary dysfunction commonly follows open heart surgery. To evaluate the effects of positive end-expiratory pressure (PEEP) upon the course and severity of impaired oxygen transfer and roentgenographic evidence of atelectasis after coronary artery bypass grafting (CABG), we randomly assigned 44 patients to positive pressure ventilation and 0, 5, or 10 cm H2O PEEP. Study groups did not differ with respect to preoperative P(A-a)O2 or time on cardiopulmonary bypass. We observed a significant reduction of P(A-a)O2 during positive pressure ventilation with 10 cm H2O PEEP and FIO2 = 0.6 (182 +/- 6 vs 135 +/- 7 mm Hg, p less than .005). Following extubation, P(A-a)O2 measurements of the three groups did not differ when compared 24, 48, 72, 96, or 120 hours after surgery. Roentgenographic atelectasis scores did not differ on the fifth postoperative day. Five days after CABG, P(A-a)O2 exceeded preoperative P(A-a)O2 (29 +/- 1 vs 18 +/- 1 mm Hg, p less than .001), although the roentgenographic distances from hemidiaphragm to lung apex were unchanged (21.2 +/- 0.9 vs 22.0 +/- 0.9 cm). We conclude that routine PEEP improves pulmonary oxygen transfer but, once discontinued, PEEP offers no sustained beneficial effect upon impaired oxygen transfer or roentgenographic evidence of atelectasis following CABG.

Blood Gas Analysis

Clinical evaluation of unsharp masking and slit scanning techniques in chest radiography.

Conventional, unsharp masking, and slit-mask (combining slit radiography and unsharp masking) techniques were compared in a clinical nodule detection study in cancer patients who were at risk for metastatic lung disease. Unsharp masking improved detection rates for nodules located in poorly penetrated areas of the chest (25% vs. 52%), with no difference in detection rates for other areas of the image and no change in false-positive detection rates. Results with the slit-mask technique did not differ significantly from those obtained with conventional techniques. In general, the differences in nodule detection rates noted between different techniques in the clinical study were less than had been observed in earlier phantom-nodule detection studies. Possible reasons for these findings are discussed.

Clinical Trials as Topic

Revision of diagnostic logic using a clinical database.

Statistical pattern-recognition techniques have been frequently applied to the problem of medical diagnosis. Sequential Bayesian approaches are appealing because of the possibility of generating the underlying sensitivities, specificities, and prevalence statistics from the estimates of medical experts. The accuracy of these estimates and the consequences of inaccuracies carry implications for the future development of this type of system. In an effort to explore these subjects, the authors used statistics derived from a clinical database to revise the diagnostic logic in a Bayesian system for generating a differential diagnostic list. Substantial changes in estimated a priori probabilities, sensitivities, and specificities were made to correct for significant under- and overestimations of these values by a group of medical experts. The system based on the derived values appears to perform better than the original system. It is concluded that the statistics used in a Bayesian diagnostic system should be derived from a database representative of the patient population for which the system is designed.

Bayes Theorem

Quality control in a medical information system.

Quality assurance techniques provide an opportunity to identify sources of error and to provide the feedback necessary to prevent their repetition. The authors outline an effort to define the steps required for effective quality management procedures in a computerized medical information system (MIS). The computerized management of medical information can be used not only to enhance current quality management activities but also to extend the realm of quality assurance to areas that have heretofore resisted management. Quality-management techniques have the potential for measuring and improving medical decision making processes central to patient care.

Abstracting and Indexing