CT in blunt chest trauma: indications and limitations.

Computed tomography (CT) is the imaging modality of choice in the assessment of patients with clinical or radiographic findings suggestive of aortic injury, bone fracture, or diaphragmatic tear following blunt chest trauma. Contrast material-enhanced spiral CT allows detection of both subtle and more obvious aortic tears. CT has overall greater sensitivity than radiography in the detection of pulmonary lacerations and pneumothoraces. CT may be indicated in cases of suspected tracheobronchial injury. CT is of limited use in the assessment of rib fractures because such injuries are of limited clinical significance and can usually be identified at radiography; however, CT provides optimal visualization of thoracic spine fractures and superior assessment of suspected sternal fractures or sternoclavicular dislocation. Targeted spiral CT with sagittal and coronal reformatted images has increased sensitivity and specificity over that provided by conventional axial CT in the detection of diaphragmatic injury. Optimal CT assessment requires careful attention to technique, including the use of intravenously administered contrast material and multiplanar reconstructed images, as well as an awareness of potential pitfalls. Although in many cases diagnosis can be made with confidence on the basis of CT findings, further investigation is often needed to confirm the diagnosis.

Diagnosis of diaphragmatic trauma with helical CT in a swine model.

OBJECTIVE: The purpose of this study was to determine whether diaphragmatic injury can be accurately diagnosed with helical CT in a swine model. The hypothesis of our study was that thin-section helical CT with sagittal and coronal reformations can reliably detect injury of the diaphragm. MATERIALS AND METHODS: The study was performed in a swine model because of the similarity of the swine thorax to the human thorax. Ten swine had a limited abdominal helical CT (enteral contrast; 3-mm collimation; pitch, 1) before and after surgical creation of a 6-cm posterolateral laceration in the left hemidiaphragm. A repeat scan was obtained after 5 cm of gastric fundus was sutured through the laceration. The gastric fundus was used because it is the most commonly herniated viscus in human diaphragmatic injury. No IV contrast was used. Control, laceration, and herniation scans were reconstructed with 1.0-mm overlap and reformated in axial, sagittal, and coronal planes. Three observers scored each reformation as control or injury (defined as laceration or herniation) in a blinded and randomized fashion. RESULTS: Using helical CT, the observers were able to distinguish diaphragmatic injury from controls (p < .0001). The sensitivity and specificity were 92% and 87%, respectively, for sagittal reformations; 85% and 87%, respectively, for coronal reformations; and 73% and 80%, respectively, for axial reformations. Sagittal reformations proved superior to coronal or axial reformations (p = .01). The results were independent of individual observers: We found no significant difference in accuracy among the three observers. CONCLUSION: Helical CT can accurately detect diaphragmatic injury in a swine model.

Management of acute pyelonephritis in an emergency department observation unit.

STUDY OBJECTIVES: To determine whether moderately to severely ill patients with acute pyelonephritis can be treated successfully on an outpatient basis, and whether any aspect of history, physical examination, or initial laboratory data predicts failure of outpatient therapy and the need for hospitalization. DESIGN: Retrospective chart review of all patients with a diagnosis of acute pyelonephritis seen during a three-year period. SETTING: Emergency department observation unit of an urban teaching hospital serving residents of the city and county of Denver. TYPE OF PARTICIPANTS: Women between the ages of 15 and 50 with symptoms, physical examination, and initial laboratory data consistent with a diagnosis of pyelonephritis. INTERVENTIONS: Patients received IV antibiotics, rehydration, analgesics, and antiemetics in an observation unit for up to 12 hours, when they were either admitted to the hospital or discharged home on oral antibiotics. MEASUREMENTS AND MAIN RESULTS: Sixty-three of 87 patients (72%) with acute pyelonephritis were managed successfully as outpatients, nine (22%) were hospitalized directly from the observation unit because they were considered to be too ill to go home, and five (6%) returned with persistent symptoms after ED therapy and were hospitalized. No clinical or laboratory variable predicted success or failure of ED observation unit therapy at the time of initial presentation. CONCLUSION: In selected patients, the observation unit may be used to initiate therapy for acute pyelonephritis. Those with an adequate clinical response to initial treatment may be discharged on oral antibiotic therapy with appropriate follow-up.

Diabetic ketoacidosis.

The classic presentation of DKA, consisting of hyperglycemia, anion gap acidosis, and ketonuria, is readily recognized. The diagnosis may be missed, however, in the patient who is euglycemic, has a negative nitroprusside test for ketones, or has a nonanion gap metabolic acidosis. Treatment includes replacement of fluid and electrolytes lost through osmotic diuresis. Failure to recognize the magnitude of total-body potassium depletion and to begin replacement despite an initially normal serum potassium level may lead to fatal cardiac arrhythmia. Serum glucose must be monitored closely to avoid hypoglycemia; dextrose should be added to the infusion once the serum glucose falls to 250 mg per dl. Insulin is required to reverse ketoacid production by the liver; low-dose therapy is recommended. Ketogenesis may be reversed inadequately unless insulin treatment is continued until the anion gap has normalized. Failure to recognize precipitating causes may result in increased morbidity and mortality from underlying infection or myocardial infarction as well as rapid relapse of ketoacidosis.

Hemodynamic effect of mannitol in a canine model of concomitant increased intracranial pressure and hemorrhagic shock.

The use of mannitol in the management of head injury has been considered a threat to hemodynamic stability in hypotensive multiply injured patients. To evaluate this contention, we compared mannitol with normal saline administration in a canine model combining elevated intracranial pressure (ICP) and hemorrhagic shock. Mongrel dogs were bled to and maintained at a mean arterial pressure (MAP) of 60 mm Hg for 30 minutes. Following this, ICP was elevated to and sustained at 25 mm Hg for 45 minutes by inflating an epidural balloon. The dogs were then randomized to resuscitation with 2 g/kg of mannitol in saline (total volume, 20 mL/kg; n = 5) or 20 mL/kg of normal saline alone (n = 5). All dogs were successfully resuscitated, and MAP returned to baseline levels in both groups. ICP was significantly lower and urine output significantly higher in the mannitol group than in saline controls (P less than .01). Moreover, cerebral perfusion pressure, cardiac index, and left ventricular stroke work index were significantly improved in dogs given mannitol versus controls during the first hour of resuscitation (P less than .05). Mannitol ameliorates increases in ICP without compromising hemodynamic resuscitation in a canine model of concomitant increased ICP and shock.

Neuromuscular blockade with anti-axoplasmic antibodies.

In the process of developing an immunopharmacologic method for identifying a "trophic" protein released from motor nerve terminals, a soluble fraction of peripheral nerve axoplasm was prepared. An attempt was made to eliminate contaminating myelin and basic protein. Antibodies were produced to soluble nerve proteins in all sheep immunized. On boosting, after a 6-week interval, the animals became weak, and some could not stand on the fifth day after injection. A distinct component of neuromuscular blockade was demonstrated electrically and in response to edrophonium. Because this syndrome was (1) in the broadest sense, an experimental allergic neuropathy but produced by a distinctly different antigen than has been utilized previously (the soluble nerve proteins represented the axoplasmic compartment) and (2) a clinical condition associated with a defect in neuromuscular transmission, this may represent a new and potentially important model in the study of neuromuscular and other neurologic diseases.