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Biomedical subjects

S P Fischer

Publications and source records attributed to S P Fischer.

13 recordsLinked to original sources
PubMed1991

Accuracy of diagnoses from magnetic resonance imaging of the knee. A multi-center analysis of one thousand and fourteen patients.

Magnetic resonance images of the knee were made for 1014 patients, and the diagnosis was subsequently confirmed arthroscopically. The accuracy of the diagnoses from the imaging was 89 per cent for the medial meniscus, 88 per cent for the lateral meniscus, 93 per cent for the anterior cruciate ligament, and 99 per cent for the posterior cruciate ligament. The magnetic resonance examinations were done at several centers, and the results varied substantially among centers. The accuracy ranged from 64 to 95 per cent for the medial meniscus, from 83 to 94 per cent for the lateral meniscus, and from 78 to 97 per cent for the anterior cruciate ligament. The results from different magnetic-resonance units were also compared, and the findings suggested increased accuracy for the units that had a stronger magnetic field. Of the menisci for which the magnetic resonance signal was reported to be Grade II (a linear intrameniscal signal not extending to the superior or inferior meniscal surface), 17 per cent were found to be torn at arthroscopy.

Adolescent↗
PubMed1989

Significance of acute posttraumatic bony encroachment of the neural canal.

Neurologic status (NS) of 80 consecutive patients with acute, traumatic thoracic, thoracolumbar, or lumbar fractures was correlated with the amount of neural canal impingement (NCI) demonstrated by computerized axial tomography (CT). Average NCI was significantly higher in the 34 patients with neurologic deficits, but the range of NCI was similar to that observed in the 46 patients with no deficits. Burst fractures and fractures in the lumbar spine had the highest average NCI but the lowest percentage of patients with neurologic deficits. The immediate, posttraumatic NS of the 80 patients studied did not directly correlate with the percent of NCI demonstrated on their CT scans.

Adult↗
PubMed1989

Progress in ankle arthroscopy.

Ankle arthroscopy is rapidly gaining in popularity as an important diagnostic and therapeutic procedure. Indications for this technique include pain, swelling, stiffness, instability, hemarthrosis, and locking of the ankle. The anteromedial, anterolateral, and posterolateral portals are most commonly used. The use of a short, 30 degrees oblique arthroscope, with an ankle holder and distractor, permits visualization of the entire joint. Operative treatment is facilitated by small joint shavers, burrs, knives, and baskets. Intraarticular problems such as chondromalacia, osteophytes, loose bodies, synovitis, osteoarthritis, fracture, and instability all can be addressed arthroscopically. Prior to this technique, the cause of chronic ankle pain was poorly understood. Now, lateral ankle impingement is a well-recognized entity that responds well to arthroscopic treatment. Ankle arthroscopy provides a safe, effective method of diagnosis and treatment with few complications. Further advances in equipment and technique should expand indications for this procedure.

Adolescent↗
PubMed1985

Levamisole in the treatment of glioblastoma multiforme.

Twenty-five patients with malignant glioma were randomized to receive radiation therapy only or radiation therapy and oral Levamisole. There were no differences in survival between the two groups and therefore no advantage in the use of Levamisole in glioblastoma could be demonstrated.

Adult↗
PubMed1979

A chronic isolated tracheal segment to study airway reflexes in conscious dogs.

Airway reflexes are difficult to study in conscious animals because associated changes in ventilation alter intrathoracic airway dimensions. By studying an isolated segment of extrathoracic trachea, we have overcome this problem. In each of 2 dogs, we created surgically an isolated tracheal segment just below the larynx, sealed at one end and tapered at the other to a 3-mm opening via a skin fistula. A chronic tracheostomy was also created near the thoracic outlet. We monitored intraluminal pressure (Pseg) of the isolated segment to reflect changes in smooth muscle tone. During anesthesia, with pentobarbital, gentle mechanical stimulation of the carina, deflation of the lungs, and asphyxia for one min increased Pseg (+9 to +/- 16 cm H2O). Lung inflation and alveolar hyperventilation decreased Pseg (-9 to -16 cm H2O). Five breaths of 2 per cent histamine aerosol increased Pseg (+5 cm H2O) when resting tone was normal. We also coated lumen of the isolated segment with tantalum powder and documented roentgenologically changes in the size of the segment that reflected changes in smooth muscle tone; constriction and dilation in response to asphyxia and lung inflation, respectively, were demonstrated directly by this technique. In conscious dogs, lung inflation decreased Pseg, and carinal stimulation increased Pseg. Instillation of lidocaine hydrochloride (Xylocaine) into the isolated tracheal segment blocked cough caused by mechanical stimulation of the segment, but carinal stimulation still caused constriction of the segment under these conditions which indicated that afferent, but not effrent parasympathetic innervation of the segment had been blocked selectively. Conversely, instillation of atropine sulfate into the isolated tracheal segment blocked constriction of the segment caused by carinal stimulation, but mechanical stimulation of the segment still caused cough under these conditions, which indicated that efferent, but not afferent parasympathetic innervation of the segment had been blocked selectively. We conclude that an innervated extrathoracic tracheal segment constricts and dilates via cholinergic pathways and is suitable for the study of airway reflexes in conscious dogs.

Animals↗
PubMed1978

Interaction between serotonin and efferent vagus nerves in dog lungs.

We anesthetized, paralyzed, and ventilated 32 dogs. In 16 dogs we measured total pulmonary resistance (RL) during inhalation of acetylcholine (ACh), serotonin (5-HT), and histamine (Hist) aerosols. Cooling both cervical vagi reduced the bronchoconstriction caused by 5-HT 64% (P = 0.001), reduced Hist-induced bronchoconstriction 17% (P = 0.003), and did not significantly reduce bronchoconstriction due to ACh. In seven dogs, we ventilated both lungs separately through a double-lumen catheter. Application of 5-HT to one lung increased the transpulmonary pressure amplitude in the homolateral but not in the contralateral lung. Cooling the homolateral vagus reduced this response 32% (P = 0.02). In nine dogs, we stimulated the peripheral ends of both cut cervical vagi before and during aerosol application of ACh, 5-HT, and Hist. ACh and Hist increased baseline RL 97 and 134%, respectively, without increasing the effect of vagal stimulation. 5-HT increased baseline RL only 27% but greatly augmented the effect of vagal stimulation (mean increase, 271%, P = 0.001). We conclude that 5-HT acts to potentiate vagal effects on airway smooth muscle via the efferent vagal pathway.

Acetylcholine↗
PubMed1977

Rapid, shallow breathing after Ascaris suum antigen inhalation: role of vagus nerves.

In five treadmill-exercising, unsedated dogs, we studied the effect of inhaled Ascaris suum antigen aerosols on minute volume of ventilation (VE), respiratory frequency (f), tidal volume (VT), total pulmonary resistance (RL), and dynamic pulmonary compliance (CLdyn), before and during cooling of the vagus nerves. With the vagi warm, inhaled antigen increased VE (mean + 62%; P less than 0.01)by increasing f (mean + 180%; P less than 0.01), despite a decrease in VT (mean - 42%; P less than 0.01). RL increased (mean + 170%; P less than 0.001) and CLdyn decreased (mean - 43%; P less than 0.005). With the vagi cool, inhaled antigen no longer affected VE, f, or VT (P greater than 0.5), although RL still increased and CLdyn still decreased. Inhalation of a bronchodilator, terbutaline, prevented the broncho-constriction induced by antigen but did not prevent the ventilatory response. We conclude that vagal afferent pathways mediate the ventilatory response to inhaled antigen and suggest that the primary stimulus for this response is not airway narrowing.

Animals↗
PubMed1976

The mechanism of rapid, shallow breathing after inhaling histamine aerosol in exercising dogs.

In 4 unsedated, exercising dogs, we studied the effects of inhaled histamine aerosol on minute volume of ventilation, respiratory frequency, tidal volume, total pulmonary resistance, and dynamic pulmonary compliance. Inhalation (5 breaths) of 1 to 2 per cent histamine aerosols increased minute ventilation (mean, 50 per cent; p less than 0.001) by increasing respiratory frequency (mean, 166 percent; P less than 0.001), despite decreasing tidal volume (mean, 42 percent; P less than 0.0001). Total pulmonary resistance increased (mean, 200 per cent; P less than 0.001.) Breathing supplemental O2 did not affect the ventilatory response to histamine. Adding external resistive loads to a dog's airway did not simulate the pattern of rapid, shallow breathing produced by histamine. Inhalation of terbutaline prevented the changes in total pulmonary resistance and dynamic pulmonary compliance but did not alter the ventilatory response to histamine. When conduction in the cervical vagus nerves (which were implanted chronically in skin loops) was blocked by cooling, the ventilatory response to histamine was abolished. We concluded that histamine stimulates breathing by stimulation of receptors whose afferent pathways are in the vagus nerves; the effective stimulus is not bronchoconstriction but is presumably due to direct stimulation of airway receptors.

Aerosols↗
PubMedDate not supplied

Arthroscopic treatment of anterolateral impingement of the ankle.

We studied 31 patients (17 females, 14 males; average age, 34) with more than 2 years of followup who had chronic anterolateral ankle pain following inversion injury. All had failed to respond to at least 2 months of conservative treatment and had negative stress radiographs to rule out instability. On physical examination, tenderness was localized to the anterolateral corner of the talar dome. Magnetic resonance imaging was the most useful diagnostic screening test, showing synovial thickening consistent with impingement in the anterolateral gutter. At an average of 24 months after injury, all patients underwent ankle arthroscopy, which showed proliferative synovitis and fibrotic scar tissue in the lateral gutter, often with associated chondromalacia of the talus. Operative arthroscopic treatment consisted of partial synovectomy with debridement of scar tissue from the lateral gutter. Postoperatively, patients walked with crutches allowing weightbearing as tolerated. Average return to sports was 6 weeks. Histopathologic analysis performed on the resected tissue showed synovial changes consistent with chronic inflammation. Results of treatment after at least 2 year followup were 15 excellent, 11 good, 4 fair, and 1 poor. Since there are several distinct causes of chronic ankle pain, we prefer to call this problem "anterolateral impingement of the ankle" and believe the term "chronic sprain pain" should be discarded.

Ankle Injuries↗