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Biomedical subjects

G W Stevenson

Publications and source records attributed to G W Stevenson.

At least 37 records · Page 2Linked to original sources
PubMed1998

A comparison of three modes of ventilation with the use of an adult circle system in an infant lung model.

UNLABELLED: We examined the efficiency of an adult circle system with adult bellows to deliver minute ventilation (VE) to an infant test lung model. A Narkomed 2B system (North American Drager, Telford, PA) using three modes of ventilator setup were used: A = time-cycled, volume-controlled using bellows excursion to control delivered volume; B = time-cycled, pressure-controlled using inspiratory pressure limit adjustment to control delivered volume; C = time-cycled, pressure-controlled using the inspiratory flow adjustment to control delivered volume. VE was measured with two compliances (normal and low) and four endotracheal tube (ETT) sizes (2.5-, 3.0-, 3.5-, and 4.0-mm inner diameter). VE was measured at peak inspiratory pressures (PIP) of 20, 30, 40 or 50 cm H2O while respiratory rate (RR) was held constant at 20 breaths/min. VE was measured as RR was set at 20, 30, 40, or 50 breaths/min while target PIP was held constant at 20 cm H2O. Data were analyzed using the multiple regression technique. With the low compliance model, VE was nearly identical regardless of the ventilator setup. With the normal compliance model, minor differences in VE were observed, especially at the highest RR and PIP. VE was dependent on RR, PIP, and lung compliance. Overall, the ventilator setup resulted in minor changes in VE. Very high PIPs were required to deliver VE to the low compliance model. ETT size did not affect VE when lung compliance was low; however, smaller ETT size was a factor when test lung compliance was normal, decreasing delivered VE at higher PIP and RR. We conclude that with a Narkomed 2B adult circle system VE is dependent on PIP, RR, and lung compliance, but not on mode of ventilator setup. IMPLICATIONS: The results of this laboratory investigation indicate that when an adult circle system is used during infant anesthesia, the ventilation delivered depends primarily on the respiratory rate, peak inspiratory pressure, and the compliance of the lung being ventilated, rather than on the specific mode of ventilator setup.

Adult↗
PubMed1998

Circovirus-like viral associated disease in weaned pigs in Indiana.

Inclusion bodies with staining affinity and ultrastructural characteristics typical of circoviruses that stained positive for porcine circovirus (PCV)-like virus were demonstrated in association with granulomatous lesions in multiple tissues of three clinically ill 10- to 12-week-old pigs. A syndrome of poor growth and wasting in 5-15% of weaned pigs was an intermittent problem on a 450-sow one-site farrow-to-finish swine farm in Indiana. Routine diagnostic testing did not demonstrate a cause. Gross examination of three representative weaned pigs from two farrowing groups over a 1-month period revealed generalized lymphadenopathy and interstitial pneumonia. A unique microscopic finding for all three pigs was granulomatous inflammation of lymphoid tissues associated with large numbers of multinucleate giant cells and characteristic viral inclusions in the cytoplasm of macrophages. These inclusions were round, homogeneous, and magenta to basophilic, varied in size (5-25 microm), and either were single or formed botryoid clusters. Ultrastructurally, these inclusions were composed of electron-dense paracrystalline arrays of small nonenveloped icosahedral viral particles that were approximately 17 nm in diameter. The sizes and shapes of the virus particles, the unique microscopic appearance of the inclusions, and the positive staining of the intracytoplasmic viral inclusions by the Feulgen technique are consistent with circoviruses. Immunohistochemistry for PCV-like virus demonstrated viral antigen in the cytoplasm of macrophages that were within inflammatory infiltrates in a variety of organs. The described inclusion bodies stained positively.

Animals↗
PubMed1997

A prospective blinded randomized trial comparing oral sodium phosphate and polyethylene glycol solutions for bowel preparation prior to barium enema.

PURPOSE: A prospective blinded randomized trial to compare oral sodium phosphate (NaP) solution with polyethylene glycol (PEG) preparations as bowel preparation prior to barium enema examination. PATIENTS AND METHODS: One hundred and ten patients consented to take part and each patient was randomly assigned to receive either NaP (Oral Fleet Prep) or PEG (Lyteprep). The barium enemas were reviewed by two radiologists blinded to the type of bowel preparation the patient had received. The colon was divided into six segments and each segment was assessed for the amount of stool and water present, the adequacy of coating, the ability to exclude inflammatory bowel disease and the presence of polyps. A score of 0-3 (failure to good) was assigned per segment on each of these criteria. RESULTS: The average individual score for the NaP group was 89.2. The average individual score for the PEG group was 88.81. No significant difference was found in the quality of bowel cleansing between the two agents. In particular there was no significant difference in the scores for water retention (two-tailed P = 0.748) and the difference for the quality of coating was considered not quite significant (two-tailed P = 0.0818). CONCLUSION: Oral sodium phosphate cleans the colon as well as polyethylene glycol solutions. The use of NaP will result in significant cost savings and improved patient compliance.

Adolescent↗
PubMed1997

Salmonella arizonae sepsis in a lynx.

A 4.5-wk-old lynx (Felis lynx) was presented for necropsy with a history of poor growth, mild diarrhea, anemia, and lethargy. The liver was enlarged and had a 7 mm long fracture that resulted in severe intraabdominal hemorrhage and death. Microscopic lesions were indicative of severe ulcerative cystitis and septicemia. Pure cultures of Salmonella arizonae were isolated from the liver, kidney, and spleen. Based on differences in the chronicity of inflammation in the urinary bladder versus other organs, we speculate that chronic cystitis caused by S arizonae lead to septicemic infection.

Animals↗
PubMed1996

Retrograde fibreoptic intubation in a child with Nager's syndrome.

PURPOSE: The authors describe a retrograde fibreoptic technique for tracheal intubation in a micrognathic child with a tracheo-cutaneous fistula. CLINICAL FEATURES: A four-year-old child with Nager's syndrome presented for surgical closure of a tracheocutaneous fistula. A tracheostomy tube had been placed in the neonatal period for management of upper airway obstruction due to severe micrognathia. At 2 1/2 yr of age, after a successful mandibular advancement procedure, the tracheostomy was removed and the child allowed to breathe through the natural airway. Preoperative physical examination revealed an uncooperative child, unable to open her mouth due to limited temporo-mandibular motion. The child was first anaesthetized with ketamine, 70 mg im, then halothane by mask. The authors were unable to open the child's mouth sufficiently to allow rigid laryngoscopy. Attempts at oral and nasal fibreoptic intubation were unsuccessful. Ultimately, the authors were able to intubate nasally by passing an ultrathin Olympus LF-P laryngoscope under direct vision through the tracheocutaneous fistula in a cephalad direction, through the larynx and nasopharynx, then out the nares. An endotracheal tube was then advanced over the fibreoptic scope and positioned distal to the tracheocutaneous fistula. The surgical procedure was successfully accomplished and the trachea was extubated postoperatively without difficulty. CONCLUSION: Retrograde fibreoptic intubation may be an option for airway management of a select group of children who cannot be intubated by traditional techniques.

Child, Preschool↗
PubMed1996

Porcine reproductive and respiratory syndrome virus does not exacerbate Mycoplasma hyopneumoniae infection in young pigs.

The purpose of this study was to determine if Porcine Reproductive and Respiratory Syndrome (PRRS) virus infection altered the severity of acute Mycoplasma hyopneumoniae (MH) infection in young pigs. Twenty five, 3-week-old male pigs were randomly assigned by litter and weight to one of 3 groups. Groups 1 (PRRS only, n = 5) and 2 (PRRS + MH, n = 10) were inoculated intranasally with PRRS virus (IN-5 isolate, 10(5) TCID50) and viremia in all pigs was confirmed by virus isolation from serum 3 days later. Group 3 (MH only, n = 10) was inoculated at the same time with virus free culture media. Seven days after virus inoculation, Groups 2 and 3 were inoculated intratracheally with MH (strain P-5722-3, 10(7) CCU). All pigs were euthanized and necropsied 28 days later, when maximum lesions of mycoplasmosis occurs. Pigs in group 1 did not cough and had no gross lung lesions, but were still viremic at necropsy. MH was isolated from all pigs in groups 2 (avg. log 5.2 +/- 1.3) and 3 (avg. log 5.1 +/- 1.5), but differences were not significant (P = 0.87). Similarly, there were no differences in average days coughing (8.9 +/- 2.8 v 11.2 +/- 4.5, P = 0.17), grossly pneumonic lung (16.5% v 17%, P = 0.91), or microscopic lung lesion scores (10.1 +/- 2.6 v 11.1 +/- 1.9, P = 0.35) between pigs in groups 2 and 3. Under these experimental conditions, PRRS virus infection did not increase the severity of experimental Mycoplasma hyopneumoniae infection in young pigs.

Animals↗
PubMed1995

Improving visualization of distal and terminal ileum during the small bowel meal: an evaluation of fluoroscopic manoeuvres.

This study evaluated a variety of fluoroscopic manoeuvres used during small bowel meals for assessment of the terminal ileum and pelvic loops of small bowel. The purpose was to identify those manoeuvres which provide maximum diagnostic yield. Fifty-six consecutive patients undergoing small bowel meal and pneumocolon entered the study. The individual manoeuvres were graded and their contribution to diagnostic quality determined. An analysis of variance was used to determine the diagnostic value of the manoeuvres. There was a significant difference in the diagnostic quality provided by the different manoeuvres. Compression of the terminal ileum with the 'F spoon' and of the pelvic bowel loops with the compression paddle in the supine position provided the best diagnostic information in single contrast. The double contrast images obtained with the pneumocolon contributed most to the diagnostic quality of the examination. The results enable us to recommend a sequence of manoeuvres which are most likely to provide diagnostic views of the terminal ileum and pelvic ileal loops yielding maximum information and optimizing use of fluoroscopic time.

Barium Sulfate↗
PubMed1995

Sodium nitroprusside metabolism in children during hypothermic cardiopulmonary bypass.

Ten children, aged 1-7 yr, presenting for repair of complex congenital heart lesions, were prospectively studied. A ketamine, halothane/isoflurane, and fentanyl anesthetic was used. After initiation of hypothermic cardiopulmonary bypass, sodium nitroprusside (SNP) was titrated as necessary to maintain a target mean arterial blood pressure of 35-60 mm Hg. Blood samples drawn immediately prior to starting SNP infusion, every 15 min during infusion, and at 1, 4, and 24 h postinfusion were analyzed for whole blood cyanide (CN-) and serum thiocyanate (SCN-). Blood gas analysis was performed every 30 min during SNP infusion. A maximum CN- level > or = 1.0 micrograms/mL was observed in two children; four others had maximum CN- levels between 0.5 micrograms/mL and 1.0 micrograms/mL (normal, < 0.2 micrograms/mL). No child had a clinically important increase of SCN- subsequent to SNP infusion. There was substantial variability in observed CN- accumulation during SNP infusion. CN- levels during the first 60 min correlated with the average SNP rate of administration (P = 0.02). Cyanide levels rapidly decreased after termination of SNP infusion and were undetectable 4 h postinfusion. Despite the short-term increase of CN- level, no child showed biochemical signs of toxicity (acidosis or increased mixed venous oxygen tension).

Cardiopulmonary Bypass↗
PubMed1995

Hepatic coccidiosis associated with hepatic necrosis in a goat.

Hepatic coccidiosis, usually caused by a member of the genus Eimeria, is common in rabbits but rare in other mammals. We describe the first reported case of naturally occurring hepatic coccidiosis in a goat. An approximately 6-month-old crossbred goat was presented with a history of diarrhea for 1 week and death. The liver had grossly visible, coalescing foci of necrosis measuring up to 6 cm in greatest dimension. Microscopically, areas of coagulative necrosis also had ectatic and hyperplastic bile ducts that contained coccidial meronts, macrogamonts, and microgamonts within the cytoplasm of epithelial cells. Bile duct lumina contained scattered oocysts. Fibrosis and aggregates of lymphocytes surrounded affected ducts. Microscopic and ultrastructural characteristics of coccidian stages were compatible with the genus Eimeria, but the species could not be determined. The small intestine also had coccidiosis; however, it was unclear whether or not the same coccidian species affected both the liver and the intestine.

Animals↗