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Biomedical subjects

T A Neff

Publications and source records attributed to T A Neff.

At least 19 recordsLinked to original sources
PubMed2003

Warming of infusion syringes caused by electronic syringe pumps.

PURPOSE: To evaluate inadvertent warming of the infusion syringe in four different types of electronic syringe pumps. METHODS: Ambient temperature and syringe surface temperature were simultaneously measured by two electronic temperature probes in four different models of commercially available syringe pumps. Experiments were performed at an infusion rate of 1 ml h(-1) using both battery-operated and main power-operated pumps. Measurements were repeated four times with two pumps from each of the four syringe pump types at a room temperature of approximately 23 degrees C. Differences among the four syringe pump brands regarding ambient to syringe temperature gradient were compared using ANOVA. A P-value of less than 0.05 was considered statistically significant. RESULTS: Syringe warming differed significantly between the four syringe brands for both the battery-operated and main power-operated mode (ANOVA, P< 0.001 for both modes). Individual differences between syringe surface and ambient temperature ranged from 0.3 to 1.9 degrees C for battery operation and from 0.5 to 11.2 degrees C during main-power operation. CONCLUSION: Infusion solutions can be significantly warmed by syringe pumps. This has potential impact on bacterial growth and the stability of drug solutions and blood products infused, as well as on the susceptibility to hydrostatic pressure changes within the infusion syringe.

Hot Temperature↗
PubMed2001

Infusion pump performance with vertical displacement: effect of syringe pump and assembly type.

OBJECTIVE: To evaluate the effect of different infusion pump models on continuity of drug delivery during vertical displacement of syringe pumps. DESIGN: Zero-drug delivery time (ZDDT), retrograde aspiration volume, and infusion bolus were recorded using the same syringe in three different models of syringe pump after lowering and elevating the pump. Compliance of each infusion assembly was measured using the occlusion release technique at 38 mmHg. RESULTS: Lowering the pump by 50 cm at an infusion rate of 1 ml/h resulted in ZDDT values ranging from 2.78 +/- 0.29 to 5.99 +/- 1.09 min. Elevating the syringe pump to its original position caused infusion boluses between 44.1 +/- 3.2 and 77.1 +/- 5.1 microl. The results demonstrated that there are large differences between syringe pump models (F = 66.8, df = 2/33, p < 0.0001) and between pumps of the same model (F = 21.3, df = 1/34, p < 0.0001). A similar pattern was found in retrograde aspiration volume and infusion bolus. CONCLUSION: All tested pumps led to clinically relevant flow irregularities during vertical displacement of the syringe pump. Thus, vertical displacement of any syringe pump connected to an infusion line delivering highly potent drugs at low infusion rates should be avoided. The variability across syringe pumps indicates that syringe pump design remains an area of potential further improvement for reducing the risk of adverse patient events.

Analysis of Variance↗
PubMed1994

Diffuse alveolar hemorrhage due to antibasement membrane antibody disease appearing with a polyglandular autoimmune syndrome.

We describe a patient with type 3-C polyglandular autoimmune syndrome who presented with diffuse alveolar hemorrhage and normal renal function. The diagnosis of antibasement membrane antibody disease was established by immunofluorescent staining of transbronchial biopsy specimens. We suggest the incorporation of antibasement membrane antibody disease into the spectrum of diseases that define the polyglandular autoimmune syndromes.

Adult↗
PubMed1988

Effects of antileukemia agents on nuclear matrix-bound DNA replication in CCRF-CEM leukemia cells.

The effects of various antileukemic agents on DNA replication associated with the nuclear matrix were investigated in CCRF-CEM leukemia cells. Residual nuclear matrices were prepared by sequential treatment of nuclei with 1.5 M NaCl, DNase I, and Triton X-100 and contained 1-5, 10, and 37% of the total nuclear DNA, protein, and phospholipid, respectively. In control cells pulse-labeled for 45 s with [3H]thymidine, the specific activity of nascent DNA was four-fold greater in the nuclear matrix fraction relative to the specific activity of the high salt-soluble (nonmatrix) DNA fraction. Pulse-labeling and reconstitution experiments indicated that this enrichment of newly replicated DNA on the nuclear matrix did not result from aggregation of nascent DNA with the matrix. A 2-h incubation of tumor cells with either 0.1 microM teniposide (VM-26), 0.2 microM VM-26, or 0.5 microM amsacrine (m-AMSA) reduced the relative specific activity of nascent DNA on the nuclear matrix by 59, 61, and 54%, respectively, compared to control cells. In contrast hydroxyurea and cytosine arabinoside, at concentrations that markedly inhibited total nuclear DNA synthesis, did not decrease the relative specific activity of newly replicated DNA on the matrix. The results provide evidence that the antiproliferative effects of the DNA topoisomerase II inhibitors, VM-26 and m-AMSA, are localized on the nuclear matrix of CCRF-CEM leukemia cells.

Amsacrine↗
PubMed1985

Demand and continuous flow intermittent mandatory ventilation systems.

A mechanical lung was used to evaluate the pressure and flow characteristics of four demand and two continuous flow intermittent mandatory ventilation (IMV) systems. The amount of negative pressure required to initiate inspiratory flow and peak expiratory resistance were measured. The inspiratory pressure required to initiate flow in the demand mode was also compared to pressures generated in the assist mode. In addition, the peak expiratory resistance was measured with four commercially available exhalation valves. Results showed that the ventilator manometer measuring internal machine pressures significantly underestimated the amount of negative pressure required to open the demand valve (p less than 0.01). There are major differences in the flow and pressure characteristics among demand and continuous flow IMV systems. Systems that impose high inspiratory elastic threshold loads and expiratory flow resistive loads may have a deleterious effect on the mechanics of breathing, and thereby limit weaning success and eventually impair the recovery of certain patients in respiratory failure. The basic methodology, especially the simple technique of inserting an aneroid manometer in line next to a patient's ET tube, for measuring proximal negative inspiratory force (NIF test) can be easily applied to any and all ventilators at any practitioner's individual institution.

Acute Disease↗
PubMed1984

Oral theophylline intoxication. A serious error of patient and physician understanding.

Twenty-two episodes of hospitalization for patients with inadvertent oral theophylline intoxication were reviewed to determine the mechanism of toxicity as well as clinical features and pharmacokinetic values. Toxic effects occurred in older subjects with poorly reversible airflow obstruction and evidence of reduced theophylline clearance. Maximum serum theophylline levels ranged from 22.4 to 104.8 mg/L. Gastrointestinal tract disturbances were the most common toxic effects; three patients had grand mal seizures. Serum theophylline levels were a poor predictor of serious toxic effects. Causes of theophylline intoxication included excessive drug ingestion by the patient, excessive dose prescription by the physician, and unrecognized drug interactions. With appropriate patient selection and education, as well as better understanding of theophylline kinetics and potential drug interactions, inadvertent oral theophylline intoxication can be minimized.

Aged↗
PubMed1979

Outpatient oxygen therapy in chronic obstructive pulmonary disease. A review of 13 years' experience and an evaluation of modes of therapy.

Thirteen years' experience with home oxygen for patients with advanced chronic obstructive pulmonary disease are reviewed. Home oxygen is safe and relieves pulmonary hypertension and elevated RBC mass in some, but not all patients. Marked clinical improvement is the most important result of long-term home oxygen use, including reduced hospitalizations and return to gainful employment for a few patients. Chronic compensated carbon dioxide retention is well tolerated and adaptive in cases of severe chronic airflow obstruction. New oxygen concentrators are effective in correcting hypoxemia and may make home oxygen administration more convenient and less expensive.

Aged↗