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Biomedical subjects

G Love

Publications and source records attributed to G Love.

15 recordsLinked to original sources
PubMed2001

Phase identification of microfeatures using EPMA methods, especially high-resolution X-ray spectroscopy

Methods of electron-probe microanalysis (EPMA), with some input from scanning and transmission electron microscopy (SEM/TEM), are applied for the identification of micro-scale constituents in a solid matrix. The subject of the study is a magnesium alloy composite, which contains silicon carbide-based fibres made by a liquid metal infiltration process. Backscattered electron imaging of the composite in the SEM showed that during composite manufacture, fibres were chemically attacked by the metal, many of the fibres exhibiting three distinct grey levels, indicative of different reaction zones, and others appearing uniformly black. EPMA measurements showed that each region contained approximately 12wt.% oxygen and that penetration of the fibre by magnesium was accompanied by a reduction in the concentration of silicon and carbon. From studying the position and shape of specific X-ray lines it was shown that magnesium penetration involved a chemical reaction with silicon oxycarbide, established in earlier EPMA studies as one of the fibre constituents. Also, in the outermost region, aluminium in the alloy reacted with free carbon in the fibre to form aluminium carbide and with magnesium to produce a Mg-Al intermetallic. The composition of black fibres was quite different from the grey ones, with negligible silicon and only a small amount of aluminium. Oxygen levels in black fibres were consistent with complete oxidation, indicating these fibres were subjected, locally, to severe oxidising conditions during composite manufacture. In the metal matrix itself, particles of a mixed magnesium/aluminium oxide, silicon carbide and magnesium silicide were observed, the latter two phases forming as silicon and carbon were ejected from fibres.

Journal Article↗
PubMed2000

Evaluating skin anesthesia after administration of a local anesthetic system consisting of an S-Caine patch and a controlled heat-aided drug delivery (CHADD) patch in volunteers.

OBJECTIVE: The objective of this study was to evaluate the depth and duration of skin anesthesia after the administration of a local anesthetic system consisting of an S-Caine (Zars, Salt Lake City, UT) patch coupled with a controlled heat-aided drug delivery (CHADD; Zars) patch. DESIGN: The study design was a randomized, double-blind, placebo-controlled, two-period crossover trial. PATIENTS: Twelve healthy adult volunteers between the ages of 18 and 50 years were enrolled. INTERVENTIONS AND OUTCOME MEASURES: After administration of the study drug or placebo, vital signs (blood pressure, pulse, respiratory rate) were monitored and recorded, and depth and duration of anesthesia were determined and recorded at defined intervals for 10 to 120 minutes after treatment. Depth of anesthesia was measured with a 21-gauge short-bevel needle attached to a depth gauge, and duration was measured using a 0 to 2 (0 = no sensation, 1 = dull sensation, 2 = sharp scratching sensation) verbal report scale. RESULTS: Statistically significant differences were noted in both depth and duration of anesthesia between the active and placebo groups. The posttreatment mean for anesthetic depth in the active group was 6.8 mm compared with 4.7 mm for control group (p = 0.050). The median anesthetic duration was greater than 120 minutes for the active group compared with less than 10 minutes for the placebo group (p = 0.001). CONCLUSIONS: The local anesthetic system consisting of a combination of S-Caine and CHADD patches provided a statistically significant dermal anesthesia effect compared with placebo in this volunteer study. If confirmed in other studies, this system has promise as a noninvasive method of producing dermal anesthesia for minor surgical procedures or intravenous insertion.

Administration, Topical↗
PubMed2000

Routine coagulation screening in the management of emergency admission for epistaxis--is it necessary?

The role of routine coagulation studies in the management of patients suffering from epistaxis is unclear. In an attempt to address this issue the case notes of all emergency admissions for epistaxis to a large Scottish teaching hospital were retrospectively reviewed over a one-year period. One hundred and forty patients (63 male, 77 female) were admitted between January and December 1998. The patients who had coagulation studies were identified and their results analysed. A total of 121 patients (86.4 per cent) had coagulation studies performed. Of these, 10 (8.3 per cent) had abnormal results and all were taking warfarin or a combination of warfarin and aspirin. No other coagulation abnormalities were identified. This study supports the view that there does not appear to be a role for routine coagulation studies in patients admitted with epistaxis. The investigation for potential haemostatic disorders should be performed when clinically indicated and, if necessary, in consultation with the haematology service.

Adolescent↗
PubMed1997

The stated and tacit impact of demographic and lifestyle factors on prioritization decisions for cardiac surgery.

In a clinical judgement analysis, we used linear regression models to reflect the impact of clinical and non-clinical cues on priority decisions, by comparing the stated prioritization policies of 30 clinicians with their actual policies as revealed by an appraisal of 50 'paper patients'. Correspondence was modest for some cues, e.g. 25 doctors said they accounted for age, but age only had a significant bearing in the derived decision models of two doctors. Correspondence between the derived and expressed weights was greatest for clinical angina grade and the presence of left main stem stenosis. Correlation between the rank order of importance between the two models was poor for most of the cues, and statistically significant only for smoking. However, stated policies made it appear that lifestyle factors such as smoking habit would influence prioritization decisions for most clinicians but policies derived from actual prioritization decisions seldom related to lifestyle or demographic variables. There were significant differences in the degree of correlation between the two models according to the experience of the clinician. However, correspondence was not significantly better for doctors with cardiological training than those without. The overall contribution of demographic and lifestyle factors to decision making appears to be small, suggesting that they should be omitted from prioritization guidelines.

Cardiac Surgical Procedures↗
PubMed1997

Iontophoretic administration of 2% lidocaine HCl and 1:100,000 epinephrine in humans.

OBJECTIVE: The primary objective was to evaluate the clinical safety and effectiveness of the iontophoretic administration of lidocaine HCl 2% and epinephrine 1:100,000 to induce local dermal anesthesia before intravenous (i.v.) cannulation. DESIGN: Section I: Open, nonblinded. Section II: Randomized, double-blind, placebo-controlled. SETTING: Section I: Healthy adult volunteers. Section II: Patients presenting for scheduled outpatient eye surgery. PATIENTS: Section I: Seven healthy adult volunteers. Section II: Forty-four patients requiring i.v. cannulation before scheduled eye surgery. INTERVENTIONS: Section I: Volunteers received iontophoresis of lidocaine HCl 2% with epinephrine 1:100,000 for a total delivery current of 40 mA min. Section II: Patients received iontophoresis for a total delivery current of 40 mA min of lidocaine HCl 2% with epinephrine 1:100,000 (active) or saline (control) immediately before intravenous cannulation with a 20-gauge i.v. catheter. MAJOR OUTCOME MEASURES: Section I: Venous blood plasma lidocaine levels, adverse events associated with iontophoresis. Section II: Patient and investigator assessment of analgesia, patient acceptance of iontophoresis, adverse events associated with iontophoresis. RESULTS: Section I: No detectable levels of lidocaine were identified in any blood plasma sample. Adverse effects were minimal and transitory. Section II: Pain was decreased following lidocaine iontophoresis in comparison with controls, as determined by the patients and investigators. Iontophoresis was well accepted by the patients. Adverse effects were minimal and transitory. CONCLUSIONS: Iontophoresis of lidocaine 2% with 1:100,000 epinephrine for short delivery times does not lead to delivery of clinically important systemic levels of lidocaine in healthy adults. Iontophoresis of lidocaine 2% with 1:100,000 epinephrine provides adequate skin anesthesia for placement of peripheral small-gauge i.v. catheters.

Adult↗
PubMed1995

The iontophoresis of fentanyl citrate in humans.

BACKGROUND: Iontophoresis is a method of transdermal administration of ionizable drugs in which the electrically charged components are propelled through the skin by an external electric field. This study was designed to determine whether iontophoresis could be used to deliver clinically significant doses of fentanyl in humans and whether there is a charge-dose relation in the delivery of fentanyl by iontophoresis. METHODS: Five adult volunteers were tested three times on separate days, once receiving passive treatment of 0.0 mA for 2 h (0 mA.min), iontophoresis 1.0 mA for 2 h (120 mA.min), and iontophoresis 2.0 mA for 2 h (240 mA.min) in an open, randomized, crossover design. Respiratory rate, heart rate, blood pressure, and hemoglobin oxygen saturation were monitored throughout the study. Plasma fentanyl concentrations were measured several times before, during, and after iontophoresis. Plasma fentanyl concentrations were measured by radioimmunoassay. RESULTS: No fentanyl was detected after passive (0.0-mA) fentanyl delivery. The following results were obtained for the 1.0- and 2.0-mA deliveries, respectively. Mean times to detectable concentrations of plasma fentanyl were 33 and 19 min; mean times to maximum concentration were 122 and 119 min; maximum concentrations were 0.76 and 1.59 ng/ml (P = 0.010); mean areas under the curve of the plasma fentanyl concentration versus time relation were 233 and 474 ng.ml-1.min (P = 0.003); and mean elimination half-lives were 354 and 413 min (P = 0.326). Only minor adverse side effects related to iontophoresis occurred. However, typical opioid-related effects occurred frequently in the 1.0- and 2.0-mA administration groups. CONCLUSIONS: Clinically significant doses of fentanyl can be administered by iontophoresis for delivery periods of 2 h. A charge-dose relation exists after administration with currents of 1.0 and 2.0 mA. Future research into the iontophoresis of fentanyl as a method of potent opioid administration is indicated.

Adult↗
PubMed1994

Respiratory-related critical events with intravenous patient-controlled analgesia.

OBJECTIVE: The objective of this study was to identify the underlying causes of respiratory-related critical events associated with intravenous patient-controlled analgesia (i.v. PCA). DESIGN: The design is an observation study of prospectively collected data. SETTING: An Acute Pain Service (APS) was established for the management of all patients receiving i.v. PCA therapy for pain management. As part of ongoing care, all respiratory-related critical events were documented and analyzed by staff members of the APS team. PATIENTS: All patients receiving i.v. PCA therapy through the APS during the period of May 1990 through October 1992 were enrolled in the study. INTERVENTIONS: Evaluation of all respiratory-related critical events was attempted to identify the underlying cause of the event and to determine if measures could be taken to prevent recurrence of similar events. OUTCOME MEASURES: Any clinical event that could have or did lead to adverse patient outcome was used as an outcome measure. RESULTS: A total of 3,785 patients received PCA therapy for a total of 11,521 patient care days. Fourteen critical events occurred, of which four led to increased patient care. There were eight programming errors (all involving misprogramming of the continuous infusion): three involved a family member activating the device, three were the result of an error in clinical judgment, and one involved a patient tampering with the device (one event involved more than one error). Of the four events that led to increased patient care, two involved a family member activating the device, one was the result of a programming error, and one was the result of an error in clinical judgment. All patients who experienced a critical event had an uneventful recovery. CONCLUSIONS: Following review of the critical events, it was determined that the design of the PCA device contributed to the misprogramming errors and the device was removed from service. Changes in the training of physicians and nurses were instituted to avoid recurrence of other errors identified. The incidence of serious respiratory-related critical events was 0.1%. i.v. PCA therapy has the risk of potentially serious complications and requires constant physician and nursing care with an active quality assurance program.

Analgesia, Patient-Controlled↗
PubMed1991

Acute pain services: a new career direction for postanesthesia nurses.

Postoperative pain management continues to be a challenge to health care professionals. To address this, hospitals across the country are developing Acute Pain Services. It is fast becoming a specialty area and is being incorporated into the realm of practice of anesthesiologists. As postanesthesia nurses, we are in a unique position to enter this new field.

Humans↗
PubMed1990

Car head restraints.

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Head Protective Devices↗