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Biomedical subjects

S P Fischer

Publications and source records attributed to S P Fischer.

At least 19 recordsLinked to original sources
PubMed2000

General anesthesia in a patient on long-term amphetamine therapy: is there cause for concern?

IMPLICATIONS: Amphetamines are powerful, sympathomimetic amines that, when used chronically, can profoundly effect a patient's cardiovascular stability during anesthesia and surgery. Amphetamines are the third most widely abused class of drugs in the United States. They also have legitimate medical use for attention deficit disorder with hyperactivity, exogenous obesity, and narcolepsy. We report a case of a patient with a 40-yr history of chronic amphetamine use having undergone two general anesthesias without complication.

Amphetamine↗
PubMed1999

Cost-effective preoperative evaluation and testing.

Cost-effective preoperative evaluation can be approached from a variety of methods, educational strategies, and use of data to modify clinical practice. This article focuses on the proposed organizational and clinical changes in the process of preoperative evaluations, the cost-effective outcomes, and the relative merits these changes provide the physicians, operating room nurses, and center administrators.

California↗
PubMed1996

Ketorolac and propofol anesthesia in a patient taking chronic monoamine oxidase inhibitors.

There is continued controversy regarding the concurrent use of monoamine oxidase inhibitors (MAOIs) and opioids in anesthesia. MAOIs are being used in both psychiatry and also in the treatment of Parkinson's disease. The adverse interaction of meperidine with MAOIs is well described in the literature. Several other opioids used in anesthesia have been reported as potentially safe and also implicated in interaction with MAOIs. We present a case report using ketorolac as a nonopioid analgesic during a general anesthesia combined with midazolam and propofol in a successful approach in a patient continuing MAOI therapy.

Analgesics, Non-Narcotic↗
PubMed1996

Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures.

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.

Biomechanical Phenomena↗
PubMed1996

Preoperative evaluation of the adult neurosurgical patient.

The purpose of this chapter is to provide the anesthesiologist with a focused review of the information needed to rationally approach the preoperative evaluation of the neurosurgical patient. The anesthesia preoperative assessment is a neuromedical evaluation of the patient's current condition integrated with the anesthesiologist's knowledge of the potential clinical and operative events that may occur. The neurosurgical patient presents the anesthesiologist with significant clinical challenges in providing the most appropriate care and the best outcome possible. The foundation of this challenge begins with the anesthesia preoperative evaluation.

Adult↗
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↗