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PubMed2004

Diagnostic testing, pre- and post-test probabilities, and their use in clinical practice.

In the process of establishing a diagnosis, the clinician calculates the disease probabilities, which keep changing as data is gathered from clinical history, physical examination and laboratory and imaging data. This paper sets out to explain, in a simple and practical way, how the characteristics of a test can be applied in order to determine post-test probability, that is, the probability of a specific disease being present. Before applying the test, we start with a pretest probability that corresponds to the prevalence of the disease. With each additional test this probability changes, until a threshold is reached that includes or excludes the clinical diagnosis. To calculate the post-test probabilities, the sensitivity and specificity of the test are used to calculate the positive and negative predictive values for a determined pretest probability, as well as likelihood ratios (through graphics or nomograms, approximations or equations). Among the test characteristics, the most useful for calculating post-test probabilities are likelihood ratios, which have several advantages over sensitivity and specificity.

Clinical Medicine↗
PubMed2004

Functional Fatigue Decreases 3-Dimensional Multijoint Position Reproduction Acuity in the Overhead-Throwing Athlete.

OBJECTIVE: To determine the effects of functional fatigue on active multijoint position reproduction in overhead-throwing athletes. DESIGN AND SETTING: A standard, repeated-measures, randomized-ordered, counterbalanced, 2-period (crossover) design was used. During the first test session, we randomly assigned subjects to either the nonfatigue or fatigue condition. Subjects underwent pretest measurements and then either a functional fatigue protocol or rest period, followed by posttest measurements. After a recovery period, subjects crossed over to the opposing condition for the second testing session. SUBJECTS: Thirteen overhead-throwing athletes competing in National Collegiate Athletic Association Division I or club baseball, with no history of upper extremity or central nervous system disorders, volunteered for this study. MEASUREMENTS: We measured active multijoint position reproduction accuracy in 3 dimensions using an electromagnetic tracking device. We noted each subject's ability to reproduce 3 positions corresponding with distinct moments of his throwing motion. A variable error score was calculated to compare the locations of the reproduced points with reference to the target point. RESULTS: A significant difference occurred between the pretest and posttest error scores in the fatigue condition. Comparisons between positions indicated that more errors were seen in the arm-cocked position than in the follow-through position under both fatigue and nonfatigue conditions. CONCLUSIONS: Functional fatigue decreased joint position sense acuity in overhead-throwing athletes. Our findings using this novel testing measurement method are in agreement with past research, with one exception. The trend toward higher error scores in the arm-cocked position would appear to contradict findings that sensorimotor system acuity increases toward end ranges of motion.

Journal Article↗
PubMed2005

Teaching intravenous cannulation to medical students: comparative analysis of two simulators and two traditional educational approaches.

This study examines the effectiveness of two virtual reality simulators when compared with traditional methods of teaching intravenous (IV) cannulation to third year medical students. Thirty-four third year medical students were divided into four groups and then trained to perform an IV cannulation using either CathSim, Virtual I.V., a plastic simulated arm or by practicing IV placement on each other. All subjects watched a five minute training video and completed a cannulation pretest and posttest on the simulated arm. The results showed significant improvement from pretest to posttest in each of the four groups. Students trained on the Virtual I.V. showed significantly greater improvement over baseline when compared with the simulated arm group (p<.026). Both simulators provided at least equal training to traditional methods of teaching, a finding with implications for future training of this procedure to novices.

Catheterization↗
PubMed2005

A longitudinal study of the learning and retention of task-specific training.

This longitudinal study evaluated the learning and retention of task-specific training during the subjects' classroom performance of a one-person pivot transfer. Twelve subjects were videotaped completing the transfer (pretest). The subjects then participated in a two-hour training session. One week later (posttest 1), and one year later (posttest 2) the subjects were videotaped again. A checklist was used to analyze the videotapes. A one-way ANOVA with repeated measures revealed that there was a statistically significant difference between the tests (F = 243.73, p-value < 0.0001). A post hoc analysis (Bonferroni procedure) indicated that the posttest 1 scores (mean = 13, SD = 0.40) were significantly higher than the pretest scores (mean = 2.96, SD = 0.39) indicating an improved score on the checklist. There was no significant difference between the scores of posttest 1 and posttest 2 (mean = 12.79, SD = 0.60) indicating that subjects continued to perform the task with proper body mechanics one year post training.

Adult↗
PubMed2005

Using willingness to pay to measure family members' preferences in mental health.

BACKGROUND: Willingness to pay is a valuation technique that has rarely been applied in mental health economics. First used in environmental economics to measure the intangible value of environmental improvements, WTP has increasingly been used in health care economics. The technique may be useful in mental health policy research where it can be critical to include the intangible impact of mental health treatment on individuals other than the person with illness, such as family members, in cost-benefit analyses. AIMS OF THE STUDY: The goal of the study was to test the application of WTP in a sample of individuals who have family members with serious mental illness. This paper describes the survey development process and the feasibility analysis that was conducted as part of the study. METHODS: A mail survey was designed by the author in two phases and utilized cognitive pretests and focus group pretests in the process of development. Qualitative analysis of this process resulted in a revised survey instrument that was then distributed to a random sample of 2000 individuals who have family members with mental illness. Feasibility was evaluated based upon the study response rate, the willingness to pay item response rate and an outlier response analysis. RESULTS: Qualitative analysis during the survey development process found that it was critical to consider two areas of concern in the application of WTP with this population in the mental health field. Some respondents experienced a highly emotional response to the initial versions of the survey, and complex probabilities were difficult for the respondents to answer. These findings resulted in significant modifications in the survey design. The analysis of response rate, WTP item non-response rate, and outlier responses found no significant concerns regarding overall feasibility of WTP with this population. DISCUSSION: Based upon the results from this study, WTP is a potentially useful tool for further research in the mental health policy and economics field. However, significant accommodations must be made in survey design to account for a possibility of a high level of emotional distress for those dealing with the illness of a family member. Some of these modifications may be in contrast to the recommendations currently being followed in health care economics. Face-to-face surveys may be preferred in some cases, such as with elderly respondents. Limitations of this study include the lack of targeted follow-up due to the anonymous study design and the fact that there are so few models for WTP studies in mental health. IMPLICATIONS FOR MENTAL HEALTH POLICY: Given that effective mental health programs can be matched with additional expenditures, it is important to explore comprehensive measures of value for treatment in cost-benefit analysis. The values of persons whose family members have serious mental illness are important to consider in setting policy. The success of this study suggests that WTP could be used in other settings, e.g., to understand community preferences for mental health treatment programs, to understand differences in preferences across multiple stakeholder groups.

Consumer Behavior↗
PubMed2005

Effects of problem-oriented willed-movement therapy on motor abilities for people with poststroke cognitive deficits.

BACKGROUND AND PURPOSE: Cognitive deficits after stroke are common and interfere with recovery. One purpose of this study was to determine whether the motor abilities of subjects who have poststroke cognitive deficits and who have received problem-oriented willed-movement (POWM) therapy will improve more than the motor abilities of subjects in the reference group who have received neurodevelopmental treatment (NDT). Another purpose of this study was to identify the relationship between cognitive function and motor abilities for both groups. SUBJECTS: The subjects recruited for this study were 36 men and 11 women with various degrees of poststroke cognitive deficits. METHODS: A randomized block design was used to assign the subjects to 2 groups. Cognitive function and motor ability were evaluated with the Mini-Mental State Examination and the Stroke Rehabilitation Assessment of Movement (STREAM). Both groups received physical therapy 5 or 6 times per week in 50-minute sessions. RESULTS: The STREAM scores improved after treatment in both groups. Main group effects were found for the lower-extremity (F=4.58, P< .05) and basic mobility (F=27.49, P< .01) subscales of the STREAM. Pretest cognitive function showed a positive relationship with posttest motor ability in the NDT group (r = .446, P< .05). However, the relationship between pretest cognitive function and posttest motor ability had no statistical significance in the POWM group (r = .101, P= .630). DISCUSSION AND CONCLUSION: These findings suggest that, regardless of a person's cognitive function, POWM intervention is effective in improving lower-extremity and basic mobilities and indicates the need to use relatively intact cognitive function or perceptual function, or both, to improve motor rehabilitation for people with cognitive function deficits.

Adult↗
PubMed2005

Library-sponsored instruction improves core informatics competencies among allied health students: a research-based case study.

Since 1999, a librarian-administered course entitled Computer Literacy for Healthcare Professionals has been required of all incoming occupational, physical, and respiratory therapy students at Stony Brook University. Outcome data from pretests/posttests and student self-assessments over a 3-year period from 2000 to 2002 demonstrate the effectiveness of the training program and of library-sponsored instruction. This study evaluated whether curriculum-integrated informatics training by librarians is effective in enabling allied health students to acquire and retain literature-searching skills. Pretests and posttests measured the impact of instructional intervention upon student acquisition of literature-searching skills; a second posttest ("post5-test") measured skill retention. The intervention group consisted of 179 subjects enrolled in baccalaureate occupational, physical, and respiratory therapy programs between 2000 and 2002; the control group consisted of 48 physician assistant students who had no formal instruction in literature searching. Student self-assessments provided qualitative outcome measures. Paired t test analysis showed that the mean posttest score for the intervention group was considerably greater at the p < 0.01 level (t = 14.868; p < 0.001) than the mean pretest score. The change is statistically significant, and the null hypothesis can be rejected. The results of this study support the conclusion that library-sponsored informatics instruction is effective in improving student acquisition and retention of literature-searching skills.

Allied Health Personnel↗
PubMed2005

Risk stratification and prognosis of patients with known or suspected coronary artery disease by use of supine bicycle exercise stress echocardiography.

BACKGROUND: The aim of this study was to assess the long-term predictive values of supine bicycle exercise stress echocardiography (ESE), and the ESE additional role compared to other traditional clinical and rest echocardiographic variables, in 607 patients with low, intermediate and high pretest risk of cardiac events. METHODS: Clinical status and long-term outcome were assessed for a mean period of 46 months (range 12-60 months). ESE was performed for the diagnosis of suspected coronary artery disease (CAD) in 267 patients (43.9%), and for risk stratification of known CAD in 340 patients (56.1%). At baseline, the mean value of wall motion score index (WMSI) was 1.22 +/- 0.36, and the mean left ventricular ejection fraction was 58.5 +/- 10.9%. RESULTS: ESE was positive for ischemia in 210 patients (34.9%), while ECG was suggestive for ischemia in 157 patients (25.8%). During the test only 97 patients (15.9%) experienced angina. At peak effort, the mean WMSI was 1.38 +/- 0.46. A low workload was achieved by 158 patients (26.1%). During the follow-up period there were 222 events, including 82 hard events (36.9%), 48 deaths (21.6%) and 34 acute non-fatal myocardial infarction (15.3%). At stepwise multivariate model, cigarette smoking (p < 0.01), peak WMSI (p < 0.001), ESE positive for ischemia (p < 0.001) and low workload (p < 0.01) were the only independent predictors of cardiac death, while positive ESE, peak WMSI, angina during the test and hypercholesterolemia were the only independent determinants of hard cardiac events. The cumulative 5-year mean survival rate according to ESE response was 95.9% in patients with negative ESE, and 83.7% in patients with positive ESE (log rank 13.6; p < 0.00001). CONCLUSIONS: ESE yields prognostic information in known or suspected CAD, especially in patients with intermediate pretest risk level. The combined evaluation of clinical variables and other ESE variables, such as peak WMSI and exercise capacity, may further select patients at greatest risk of cardiac death in the overall population.

Coronary Artery Disease↗
PubMedDate not supplied

Effects of 2 ankle fatigue models on the duration of postural stability dysfunction.

CONTEXT: Muscle fatigue is generally categorized in 2 ways: that caused by peripheral weakness (peripheral fatigue) and that caused by a progressive failure of voluntary neural drive (central fatigue). Numerous variables have been studied in conjunction with fatigue protocols, including postural stability, maximum voluntary contraction force, and reaction time. When torque recordings fall below 50% of a maximum voluntary contraction, the muscle is described as fatigued, but whether this value is a good indicator of fatigue has not been studied. OBJECTIVE: To compare the effects of 2 ankle musculature fatigue protocols (30% and 50%) on the duration of postural stability dysfunction. DESIGN: To assess differences between the 30% and 50% fatigue protocols, we calculated a 1 between-groups factor (subjects) and 2 within-groups factors (fatigue, test) analysis of variance. SETTING: E.J. Nutter Athletic Training Facility. PATIENTS OR OTHER PARTICIPANTS: Twenty subjects (10 men, 10 women; age = 21.15 +/- 2.23 years; height = 172.97 +/- 9.86 cm; mass = 70.62 +/- 14.60 kg) volunteered for this study. Subjects had no history of lower extremity injury, vestibular or balance disorders, functional ankle instability, or head injury in the past 6 months. INTERVENTION(S): On separate days, subjects performed isokinetic fatiguing contractions of the plantar flexors and dorsiflexors in a 30% protocol (70% decrease in strength) and a 50% protocol (50% decrease in strength). MAIN OUTCOME MEASURE(S): Baseline and postfatigue postural stability scores were determined before and after the isokinetic fatiguing contractions. Plantar-flexion peak-torque measurements were obtained for the 2 fatiguing protocols. Three prefatigue and 12 postfatigue postural stability trials were recorded. Velocities for testing were 60 degrees /s for plantar flexion and 120 degrees /s for dorsiflexion. RESULTS: Sway velocity was significantly greater when the ankle was fatigued to 30% (1.56 degrees /s) than in the 50% condition (1.36 degrees /s). For the 30% protocol, sway was significantly impaired when the pretest condition (1.19 degrees /s) was compared with posttest trial 1 (2.34 degrees /s), trial 2 (2.37 degrees /s), and trial 3 (1.71 degrees /s). For the 50% protocol, sway was significantly impaired when the pretest condition (1.27 degrees /s) was compared with posttest trial 1 (2.02 degrees /s). CONCLUSIONS: The 30% fatigue protocol resulted in significantly longer impairment of postural stability than the 50% protocol. Because the 30% protocol resulted in a greater effect but was relatively short-lived (approximately 75 to 90 s), it is more useful for research purposes.

Journal Article↗
PubMedDate not supplied

Effectiveness of structured teaching program in improving knowledge and attitude of school going adolescents on reproductive health.

INTRODUCTION: Development of knowledge and attitude takes place during the adolescent period, which can have lifelong effects on the individual, family and society. Proper education in this age group is important for prevention of untoward social and health related problems. OBJECTIVE: To find out the effectiveness of structured teaching program in improving knowledge and attitude of school going adolescents on reproductive health. MATERIALS AND METHODS: An experimental study with pretest - posttest control group design was carried out in four selected schools with similar settings in Dharan town of Nepal. All the subjects were divided into two groups: experimental and control, each comprising of two subgroups of 50 boys and 50 girls. Structured teaching program consisting of information on human reproductive system was used as a tool of investigation for the experimental group, whereas conventional teaching method was used for the control group. RESULTS: A total of 200 Adolescent school students were included in this study. The mean (+/-SD) pretest score of the experimental group on knowledge of reproductive health was 39.83 (+/- 16.89) and of the control group was 39.47(+/- 0.08). The same of experimental group after administration of the structured teaching program (84.60+/-10.60) and of the control group with conventional teaching method (43.93+/-10.08) was statistically significant (p<0.001). Similarly, the post-test scores of knowledge of the groups on responsible sexual behaviour and their attitude towards reproductive health were better in the experimental group than in the control group (p<0.001). CONCLUSION: The knowledge of adolescent school students on reproductive health is inadequate. The use of structured teaching program is effective in improving knowledge and attitude of the adolescents on reproductive health.

Adolescent↗
PubMed2005

Changes in students' perceptions of interdisciplinary practice reaching the older adult through mobile service delivery.

This study examined students' perceptions of interdisciplinary health care practice in a facilitated, community-based practicum experience. Students' perceptions of interdisciplinary practice relative to their own profession and other health disciplines were examined before and after involvement in mobile service delivery to the older adult in a collaborative team approach. The Interdisciplinary Education Perception Scale was used to collect data before and after planned and facilitated interdisciplinary experiences of students enrolled in health professional programs (nursing, dietetics, physical therapy, occupational therapy, pharmacy, health education, social work, and physician assistant). Univariate repeated-measures analysis of variance revealed significant pretest to posttest and discipline effects following the interdisciplinary interaction of students in the practicum experience. Univariate analysis revealed a significant change in students' perceptions of professional competence and autonomy, actual cooperation and resource sharing within and across professions, and understanding of the value and contributions of other professionals from pretest to posttest. The findings support the need for educators to facilitate communication through innovative interdisciplinary clinical opportunities for health professions students to influence perceptions that promote active participation in a team approach to care delivery in an increasingly complex health care system.

Aged↗
PubMed1993

1992 Student Writing Contest-1st Runner-up: A Comparison of Thermotherapy and Cryotherapy in Enhancing Supine, Extended-leg, Hip Flexion.

Eighteen healthy subjects (13 females and 5 males) were pretested and posttested under two treatment conditions in order to compare the effects of cryotherapy and thermotherapy on supine, extended-leg, hip flexion measurements. Cryotherapy treatments consisted of crushed ice bags secured to the posterior thigh for 20 minutes. On a separate day, thermotherapy treatment of moist heat pads were applied to the posterior thigh for 20 minutes. For pretest and posttest measurements, the subject's extended leg was taken to the end feel of passive hip flexion as maximum range of motion was assessed using a goniometer. Both cryotherapy and thermotherapy significantly improved immediate range of motion; however, there were no differences between the two treatment conditions. These results suggest that athletes wishing to obtain maximum range of motion immediately after treatment may select either ice or heat modalities. Individual conditions and preferences can be used to dictate treatment selection.

Journal Article↗
PubMed1998

Concentric versus enhanced eccentric hamstring strength training: clinical implications.

OBJECTIVE: Hamstring injuries can be quite debilitating and often result in chronic problems. Eccentric muscle actions are often the last line of defense against muscle injury and ligament disruption. Traditionally, the focus of hamstring strength rehabilitation has been on concentric muscle actions. The purpose of our study was to compare hamstring muscle strength gains in concentric and eccentric hamstring strength training. DESIGN AND SETTING: A randomized-group design was used to examine differences in 1-repetition maximum (1 RM) and isokinetic strength values among 3 groups of subjects. Subjects were tested in a biomechanics laboratory using an isokinetic dynamometer, while training was carried out in a physical therapy outpatient clinic. SUBJECTS: Twenty-seven healthy male subjects (age = 22.9 +/- 3.1 years, wt = 81.8 +/- 12.9 kg, ht = 178.6 +/- 7.2 cm) participated in this study. Subjects were randomly assigned to 1 of 3 treatment groups: eccentric training, concentric training, or control. MEASUREMENTS: Subjects performed hamstring curls using an isotonic weight training device. Pretest 1 RM weight values were determined for all subjects using a standardized 1 RM protocol. In addition, maximum concentric and eccentric isokinetic strength values for knee-flexion strength were determined. Control group subjects refrained from weight training for 6 weeks. Subjects in the training groups trained 2 days per week for 6 weeks (12 sessions). After 6 weeks of training, all subjects returned for 1RM and isokinetic posttesting. RESULTS: The concentric group improved 19%, while the eccentric group improved 29%. The control group subjects did not show any significant change over the 6 weeks. In addition, there were improvements in eccentric isokinetic peak torque/ body weight ratios at both 60 degrees s and 180 degrees from pretesting to posttesting in the eccentric training group only. CONCLUSIONS: Our results demonstrate the effectiveness of isotonic strength training on the development of hamstring muscle strength. More important is the dramatic effect of eccentric strength training on overall hamstring muscle strength, both isotonic and isokinetic. Clinicians should consider using eccentric hamstring strengthening as part of their rehabilitation protocols for hamstring and knee injuries.

Journal Article↗
PubMed2006

Time dependency of walking classification in stroke.

BACKGROUND AND PURPOSE: To facilitate optimal stroke rehabilitation, valid interpretation of observed functional recovery is required. The purpose of this study was to examine the longitudinal relationship between comfortable walking speed and Functional Ambulation Categories (FAC) scores for physically independent gait. SUBJECTS: This study was a prospective cohort study with 73 subjects who were severely affected by acute stroke. METHODS: Functional Ambulation Categories classification and walking speed were measured between weeks 4 and 26 after stroke. The responsiveness of walking speed measurements for detecting clinically important speed changes was determined, and the longitudinal association between walking speed and FAC scores and its time dependency were established. This relationship subsequently was scrutinized for possible speed changes occurring within specific FAC scores. Responsiveness ratios, random coefficient analysis, paired Student t tests, and the Cohen kappa statistic were used for statistical analyses. RESULTS: Responsiveness ratios exceeded the smallest detectable differences. Random coefficient analysis demonstrated a significant between- and within-subject coefficient and a significant negative interaction between timing of measurements and FAC scores. Paired Student t tests revealed mostly significant pretest-posttest differences in walking speeds, and all kappa values for pretest-posttest FAC scores were significant. DISCUSSION AND CONCLUSION: Walking speed measurements are sensitive for detecting clinically important changes. Functional Ambulation Categories scores are dependent on the timing of comfortable walking speed measurements after stroke. Moreover, there are indications that, in this relationship, repeated FAC appraisals are not only based on steady walking speeds, but that the walking speeds related to a specific FAC appraisal also change and, over time, may shift gradually from higher to lower speeds.

Acute Disease↗
PubMed2006

The effect of interferon alpha plus ribavirin on health-related quality of life in chronic C hepatitis. The Romanian experience.

BACKGROUND AND AIM: Interferon plus Ribavirin represent the most effective therapy for chronic hepatitis C. Its efficiency is limited by the occurrence of numerous side-effects. A previous study observed in Romanian patients an impairment of quality of life in chronic viral hepatitis C before antiviral therapy. We looked for the effect of this treatment on health-related quality of life in chronic hepatitis C when measured immediately after the antiviral therapy. METHODS: 35 patients with hepatitis C were given Interferon alpha 3MU tiw plus Ribavirin 1000-1200 mg for 48 weeks. Questionnaire-based assessments of health-related quality of life were performed before and immediately after the treatment using the SF-36 questionnaire. Also, in pretest, the health-related quality of life scores were compared in these patients with "normal" subjects (matched on age and sex). In order to compensate for the lack of a specific control group during the longitudinal study, normative comparisons were performed in posttest. RESULTS: Before treatment, patients had significant impairment in all SF-36 concepts compared to "normal" controls (all p < 0.05). The level of transaminases before the treatment was high (out of the normal range) and decreased after the treatment, reaching the normal range (27 of 35). Immediately after the treatment, SF-36 scores did not show any significant differences, as compared to the pretest, no matter what the viral response was (p > 0.10). CONCLUSIONS: Patients with chronic viral hepatitis C have a markedly reduced health-related quality of life both before and after the treatment. The antiviral therapy does not influence the level of the quality of life, when measured immediately after finishing the treatment.

Adult↗
PubMed2006

SPECT-guided CT for evaluating foci of increased bone metabolism classified as indeterminate on SPECT in cancer patients.

UNLABELLED: Hybrid cameras combining SPECT and spiral CT offer the opportunity to obtain a diagnostic-quality CT image of scintigraphically suggestive lesions that directly correlates with the SPECT image. The field of view of the CT scan can be adapted on the basis of the SPECT findings ("SPECT-guided CT"). The aim of the present study was to investigate the value of SPECT-guided CT in the assessment of foci of increased bone metabolism classified as indeterminate on SPECT. METHODS: Of 272 consecutively examined patients with histologically confirmed malignancy who underwent bone scintigraphy, 112 (41%) required further workup by SPECT because a definite diagnosis could not be established using whole-body planar scintigraphy alone. In 57 of these patients, SPECT was accompanied by inline CT over the body region of interest; the remaining 55 subjects underwent only stand-alone SPECT for logistic reasons. The 57 SPECT/CT studies were retrospectively evaluated by readers who were unaware of the clinical pretest probability and the findings on the planar scans. In total, 52 lesions in 44 patients were rated as indeterminate on the SPECT images. Afterwards, the corresponding SPECT/CT images were analyzed and the findings previously rated as indeterminate were classified either as definitely benign, indeterminate, or definitely malignant. RESULTS: Of the 52 indeterminate findings on SPECT, 33 (63%) could be correlated with benign findings on CT. These findings involved mostly osteochondrosis, spondylosis, and spondylarthrosis of the spine. Fifteen lesions (29%) could be correlated with osteolysis or sclerotic metastases on CT. Even after analysis of the SPECT/CT images, 4 lesions (8%) remained indeterminate. These lesions were in the ribs and the scapula. CONCLUSION: SPECT-guided CT was able to clarify more than 90% of SPECT findings classified as indeterminate in an analysis that was masked as to clinical pretest probability and the planar scan findings. Further studies carefully addressing the cost efficiency of this new technology and its actual clinical value are encouraged by this observation.

Bone and Bones↗
PubMed2004

Use of radiopaque contrast agents for the interventional pain physician.

Intravenous contrast (IV) agents are used by Interventional Pain Management specialists for accurate localization of needle positions and spread of contrast agents to delineate pertinent anatomy. IV contrast agents are classified chemically as non-ionic or ionic monomers and dimers. Non-ionic IV contrast agents are more hydrophilic which makes them less neurotoxic. They also have a lower osmolality and produce fewer side effects. The desirable properties of IV contrast agents include satisfactory radiopacity, stability, pharmacological inertness and minimum sensitization. Physicians must obtain an informed consent for use of IV contrast agents prior to the procedure. A detailed history of allergies to iodine containing foods is a contraindication to using IV contrast agents. Reactions to IV contrast agents may produce mild to severe symptoms. Facilities where IV contrast agents are administered must be well equipped with resuscitation equipment, medications and available trained staff. Pretesting with a small intradermal dose or subcutaneous injections, will not predict adverse reactions. Premedication with antihistamines, anticholinergics and diazepam is less effective than with corticosteroids. Pretesting cannot be relied upon to predict severe reactions and may itself be hazardous for the patient. The frequency of renal insult is especially high with pre existing azotemia, diabetes mellitus or elevated serum creatinine. Patients over the age of 65 years, with multiple myeloma, hypertension or hyperuricemia are at increased risk for developing nephrotoxicity.

Journal Article↗
PubMed1977

Actions of iontophoretic phenytoin and medazepam on hippocampal neurons.

In rats anesthetized with methoxyflurane, phenytoin (DPH) and medazepam (MDZ) were administered iontophoretically to pyramidal and granule cells discharging spontaneously or being driven by acetylcholine or glutamic acid. The objectives were to determine if: 1) these anticonvulsant agents exert direct effects on the rates of discharge of hippocampal neurons; 2) similarities exist between responses elicited by DPH and MDZ; and 3) pyramidal and granule cells differ in their responsiveness to the drugs. The firing rates of 38% of spontaneously active neurons were reduced by iontophoretic DPH. The incidence of depression by DPH depended upon the pretest discharge rates of the cells. Only 5% of cells with spontaneous rates less than 12/sec were depressed by DPH, but 80% with rates faster than 12/sec were inhibited. MDZ depressed 79% of spontaneously firing neurons regardless of pretest discharge rate. A majority of neurons whose firing rates were facilitated by either acetylcholine or glutamate were depressed by DPH or MDZ ejected iontophoretically. Pyramidal and granule cells responded similarly to putative transmitters, but differentially to the drugs. MDZ depressed a much greater proportion of spontaneously active granule cells then DPH. Phenytoin and MDZ differed with regard to the incidence of depression of spontaneous discharges, inhibition of slow firing cells, the proportion of granule cells depressed, and the duration of effect. These differences may be due to potency and pharmacokinetic factors or dissimilar mechanisms of action when the compounds are applied directly to single neurons.

Animals↗