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Biomedical subjects

K B Johnson

Publications and source records attributed to K B Johnson.

At least 19 recordsLinked to original sources
PubMed2001

Barriers that impede the adoption of pediatric information technology.

BACKGROUND: Information technology (IT) is a critical but underused component of health care. Many factors contribute to the inconsistent adoption of IT. OBJECTIVE: To review the literature to better elucidate barriers that are likely to affect the adoption of IT by pediatric professionals. DATA SOURCES: Manuscripts were found using a MEDLINE search combining the terms medicine, information systems, and technology transfer. I also obtained references cited by relevant articles. Finally, I explored the Internet using http://www.google.com and http://www.northernlight.com. STUDY SELECTION: Articles discussing barriers or factors affecting the adoption of IT were considered for inclusion. Articles unrelated to clinical IT were excluded. DATA SYNTHESIS: A variety of barriers exist that affect the adoption of useful technologies. Situational barriers include challenges imposed by the current national health environment, financial and legal risks associated with technology purchasing and use, and access to technology. The most significant barrier is that pediatric health care practitioners may lack the knowledge or training to use IT effectively. CONCLUSIONS: Although some barriers exist that may be challenging to overcome, other barriers, such as the lack of knowledge about the uses of IT, are imminently solvable. Efforts to overcome these barriers should begin in earnest and should include educating stakeholders in the care of children and adolescents, as well as improving the knowledge about various technologies available to support pediatric and adolescent health care.

Biomedical Technology↗
PubMed2001

Influence of hemorrhagic shock on remifentanil: a pharmacokinetic and pharmacodynamic analysis.

BACKGROUND: Hemorrhagic shock is known to alter significantly the pharmacokinetics of fentanyl, an opioid that requires delivery to the liver for metabolism. The authors hypothesized that the pharmacokinetics and pharmacodynamics of remifentanil, an esterase metabolized opioid that does not require delivery to a metabolic organ, would be altered less by hemorrhagic shock that those of fentanyl. METHODS: Sixteen pigs were assigned randomly to control and shock groups. The shock group was bled using an isobaric hemorrhage model. Remifentanil 10 microg x kg(-1) x min(-1) was infused for 10 min to both groups. Arterial samples were collected for remifentanil concentration assay. Pharmacokinetic parameters were estimated using a three-compartment model. The electroencephalogram spectral edge was used as a measure of drug effect. The pharmacodynamics were characterized using a sigmoid inhibitory maximal effect model. RESULTS: Remifentanil blood levels were higher in the shocked group. The central clearance was slower and the central compartment was smaller in shocked animals. No difference between groups was observed in the magnitude or time course of the remifentanil-induced decrease in spectral edge. CONCLUSIONS: Hemorrhagic shock altered the pharmacokinetics of remifentanil, suggesting that less remifentanil would be required to maintain a target plasma concentration. However, because of its rapid metabolism, the impact of hemorrhagic shock on the concentration decline of remifentanil after termination of the infusion was minimal. Hemorrhagic shock did not alter the pharmacodynamics of remifentanil.

Analgesics, Opioid↗
PubMed2001

Hopkins Teen Central: Assessment of an internet-based support system for children with cystic fibrosis.

UNLABELLED: Support groups are an important therapeutic intervention for patients with chronic debilitating illnesses. Patients who are difficult to assemble in one physical location may benefit from participating in an electronic support group (ESG). ESGs for adolescents have not been evaluated, although studies have shown a benefit to adult ESGs. Our goals were to create a web-based support service for adolescents with cystic fibrosis (CF) and to qualitatively and quantitatively measure the effects that such a support site could have on patients' relationships with the clinic faculty and staff, access to and interaction with peers with CF, and understanding of CF. METHODS: A highly interactive ESG was developed after discussions with a team of CF specialists and patients. Eighteen of 37 teenagers with CF agreed to use this site. Each patient was asked to assess his or her perceived availability of and comfort with the clinic staff and faculty, perceived support available through peers, knowledge about CF, and perceived usefulness of the Internet as a support tool. RESULTS: Participants logged into the site an average of 4 times each month. Teens who owned home computers accessed the site somewhat more frequently than did teens who were provided with home Internet access for the study. Most activity occurred in those sections of the site that described the participants and that allowed them to socialize. Over one half of the participants e-mailed each other at least once a week, with 77% e-mailing peers at least every other week. There was no significant difference in the participants' scores on a quiz about CF at the beginning and the end of the study; however, there was a significant decrease in perceptions about their knowledge about CF. At the conclusion of the study, participants believed that they had more friends who they could relate to than they did at the beginning of the study. Clinic staff noticed an increase in references to peers among the group who were using the site. In addition, 4 of the teens expressed a desire to get together to meet each other as a result of their interactions on the web site. There was no significant change in perceptions about the perceived availability and comfort with the clinic staff and faculty, support available through peers, knowledge about CF, and the usefulness of the Internet as a support environment. Managing the project was extremely easy, with virtually no technical or procedural issues arising during the study. CONCLUSIONS: Teenagers with a chronic disease will actively participate in an ESG. The social and expressive aspects of their involvement with this support group hold much promise.

Adolescent↗
PubMed2001

The palm as a real-time wide-area data-access device.

Handheld wireless technologies offer great promise in helping to improve healthcare. However, it is not clear whether off-the-shelf wireless networking will work as well within medical centers as this technology works outside of the medical center. Therefore, we evaluated the coverage of wide-area wireless technology within two representative academic medical centers. The study determined the rate of connectivity by testing both the Palm VII and the Minstrel V modem in a set of locations typically frequented by house staff in their daily activities. Within one hospital, connectivity was 59% for OmniSky service, and 78% for Palm.net. The second hospital's connectivity was over 93% with both devices. Differences in connectivity were likely due to the number of rooms visited with externally exposed walls, the suburban versus urban location of the academic medical center, and the relative location of service transponders. When examined by the Johns Hopkins Clinical Devices Laboratory, both devices were found to operate without interfering with other hospital equipment.

Academic Medical Centers↗
PubMed2000

Quantifying the literature of computer-aided instruction in medical education.

PURPOSE: To characterize the literature about computer-aided instruction (CAI) as it relates to medical education. METHOD: A descriptive study using the Medline and ERIC databases, reviewing articles pertaining to CAI for medical professionals. The literature was evaluated with respect to type of article, journal, language, and year of publication. RESULTS: The search yielded 2,840 citations, 92% of which were in English. The number of journals with at least one citation was 747. Less than 5% of the 5,147 authors had three or more articles published in the CAI literature. Of the citations with abstracts, 60% were demonstrations of a CAI application, 11% were media-comparative studies, and 13% were analyses of the CAI field. While the pace of article publication increased markedly over time, the percentages of article types did not change significantly over time. Less than 10% of CAI articles appeared in core medical journals. CONCLUSION: Medical CAI is an increasingly popular topic of research and publication. However, these studies appear in journals with smaller circulations, are predominantly demonstration articles, and are generally written by authors with two or fewer publications. Evaluation articles remain less common. A series of analytic articles has appeared offering substantive suggestions for better research design. These suggestions appear to have gone unheeded. CAI investigators need be more aware of the gaps in the existing body of CAI publications, and the inherent difficulties of this type of research, if this literature is to move beyond this early stage of development.

Computer-Assisted Instruction↗
PubMed2000

Effectiveness of a clinical pathway for inpatient asthma management.

BACKGROUND: Clinical pathways for asthma are tools that have the potential to improve compliance with nationally recognized management guidelines, but their effect on patient outcomes has not been documented. OBJECTIVES: To determine the effect of an asthma clinical pathway on patients' length of stay, use of nebulized beta-agonist therapy while hospitalized, and use of acute care clinics for 2 weeks after discharge. DESIGN/METHODS: The study was a randomized, controlled trial. Patients between the ages of 2 and 18 years admitted with an asthma exacerbation and not under the care of an asthma specialist were eligible for the study. Patients were randomized either to a conventional ward (control group) or to a ward using the clinical pathway (intervention group). For 2 weeks after discharge, we collected data to determine whether patients visited a health care provider for worsening asthma. RESULTS: One hundred ten patients (26%) were enrolled. Control and intervention groups had similar demographic and asthma severity profiles. The intervention group had an average length of stay 13 hours shorter than did the control group. In addition, at every dosing interval, the intervention group received less nebulized beta-agonist therapy. There were no deaths in either group. CONCLUSION: A clinical pathway for inpatient asthma decreased the length of stay and beta-agonist medication use with no adverse outcomes or increased acute-care encounters through 2 weeks after discharge.

Administration, Inhalation↗
PubMed1999

Balloon rupture during stent implantation: A novel technique of salvage with a new manual power injector.

Pinhole leak or rupture of a stent delivery balloon is a well-recognized technical problem encountered in vascular interventions. This event leads to inadequate stent expansion. These stents cannot be fully deployed with the same balloon and frequently the balloon cannot be retrieved without dislodging the stent. We describe a technique for successful stent deployment in such situations using the Oz Power Syringe, a new manual power injector. Cathet. Cardiovasc. Intervent. 48:74-77, 1999.

Aged↗
PubMed1999

Internet TV set-top devices for web-based projects: smooth sailing or rough surfing?

BACKGROUND: The explosion of projects utilizing the World Wide Web in the home environment offer a select group of patients a tremendous tool for information management and health-related support. However, many patients do not have ready access to the Internet in their homes. For these patients, Internet TV set-top devices may provide a low cost alternative to PC-based web browsers. METHODS: As a part of a larger descriptive study providing adolescents with access to an on-line support group, we investigated the feasibility of using an Internet TV set-top device for those patients in need of Internet access. RESULTS: Although the devices required some configuration before being installed in the home environment, they required a minimum of support and were well accepted by these patients. However, these patients used the Internet less frequently than their peers with home personal computers--most likely due to a lack of easy availability of the telephone or television at all times. CONCLUSION: Internet TV set-top devices represent a feasible alternative access to the World Wide Web for some patients. Any attempt to use these devices should, however, be coupled with education to all family members, and an attempt at providing a dedicated television and phone line.

Adolescent↗
PubMed1999

Restricted natural language processing for case simulation tools.

For Interactive Patient II, a multimedia case simulation designed to improve history-taking skills, we created a new natural language interface called GRASP (General Recognition and Analysis of Sentences and Phrases) that allows students to interact with the program at a higher level of realism. Requirements included the ability to handle ambiguous word senses and to match user questions/queries to unique Canonical Phrases, which are used to identify case findings in our knowledge database. In a simulation of fifty user queries, some of which contained ambiguous words, this tool was 96% accurate in identifying concepts.

Computer Simulation↗
PubMed1999

The use of a new mechanically advantaged syringe for performing coronary intervention.

OBJECTIVE: To determine the utility of a new mechanically advantaged syringe in the performance of percutaneous coronary intervention. BACKGROUND: A new mechanically advantaged syringe has been developed to perform cardiovascular imaging. We wanted to assess the utility of this device in the performance of small catheter percutaneous coronary intervention. Data from coronary interventions performed with the standard technique at our institution, using a 10 ml manual syringe, were compared to the use of a new mechanically advantaged syringe. Contrast utilization during the standard technique was assessed by obtaining data from fifty consecutive successful single-vessel coronary interventions (angioplasty with or without stenting). After an initial learning experience with the mechanically advantaged syringe, fifty consecutive successful single-vessel coronary interventions were assessed. Most interventions performed using the mechanically advantaged syringe were with 6 French catheters. Detailed contrast utilization information was gathered. RESULTS: During the standard method of performing coronary intervention, 216 +/- 114 ml of contrast were used. Utilizing the mechanically advantaged OZ Power Syringe (Cardiovascular Innovations Inc., Athens, Texas), the contrast use was reduced to 66 +/- 39 ml (p < 0.0001) per case. The syringe also allowed excellent visualization despite using a smaller guide catheter system. CONCLUSION: The OZ Power Syringe can be utilized effectively in percutaneous coronary intervention. Our preliminary data suggest that there may be reduced contrast use without sacrificing image quality.

Angioplasty, Balloon, Coronary↗
PubMed1998

Remifentanil and propofol combination for awake craniotomy: case report with pharmacokinetic simulations.

Remifentanil and propofol infusions were used to provide neuroleptanalgesia during an awake craniotomy to resect a left frontoparietal glioblastoma near the motor speech center. This operation presented anesthetic requirements ranging from adequate analgesia during bone flap removal to an appropriate level of consciousness during cortical speech mapping. We performed pharmacokinetic simulations to estimate the effect site concentrations of propofol and remifentanil as the infusion rates were modulated to meet the dynamic sedation and analgesic needs of the operation. Simulations revealed that changes in infusion rates were quickly followed by changes in the effect site concentrations which corresponded well with the desired changes in patient sedation and analgesia. We propose that remifentanil and propofol in combination may be a useful technique for awake craniotomy.

Anesthesia, Intravenous↗
PubMed1997

The rubber meets the road: integrating the Unified Medical Language System Knowledge Source Server into the computer-based patient record.

Ongoing improvements in the content of the Unified Medical Language System, coupled with the recent release of the Internet-based Knowledge Source Server (KSS), have prompted us to develop an interface between the KSS and our computer-based patient record. We confronted many challenges while developing a robust interface to an Internet-based server, and in integrating the process of codification into the workflow of clinicians. An initial evaluation of the interface in the clinical environment suggests that acceptable performance is attainable. The benefits of using an Internet-accessible tool in a clinical information system appear to justify the effort required.

Humans↗
PubMed1997

The role of histamine in mediating the decompensatory phase of hemorrhagic shock in the rat.

Our laboratory has previously reported that plasma histamine levels rise significantly and coincidentally with the onset of the decompensatory phase of isobaric hemorrhagic shock in rats. The histamine levels seen in shock were comparable to those that induce profound vasodilatation in many vascular beds under normovolemic conditions. We, therefore, sought to determine whether the elevation in plasma histamine contributes to the cardiovascular collapse seen in the decompensatory phase of hemorrhagic shock. Sprague-Dawley rats were bled according to an isobaric bleeding protocol which maintained the mean arterial blood pressure (MAP) at 40 mmHg until death. Selected H1 (diphenhydramine) and/or H2 (cimetidine and famotidine) antagonists were administered at 75% of the estimated peak shed blood volume (PSBV), a point preceding the rise in plasma histamine. Plasma histamine levels in all groups were similar throughout the time course of hemorrhagic shock. None of the histamine receptor antagonists affected the time of onset or the rate of decompensation. Suspecting that hypotension may alter the animal's response to histamine, we investigated the effect of exogenous histamine administration on MAP before and after hemorrhage. In unbled animals, bolus histamine infusions (.6 mg/kg) dropped the MAP by 62.0 +/- 2.7 mmHg, however, in animals bled to 40 mmHg, histamine dropped the MAP by 7.2 +/- 2.7 mmHg (p = .002). On the basis of the results of these two interventions, we conclude that histamine is not an important mediator of the cardiovascular collapse seen in the decompensatory phase of hemorrhagic shock in the rat.

Adaptation, Physiological↗
PubMed1996

Functional classification of antidepressants based on antagonism of swim stress-induced fos-like immunoreactivity.

Autoradiographic analysis of 14C-2-deoxyglucose (2-DG) uptake and immunocytochemical assessment of Fos-like immunoreactivity (Fos-LI) were used to assess swim stress-induced changes in metabolic activity in brain and to define the effect of chronic treatment with antidepressants from different pharmacological classes. Saline-treated rats processed in the forced swim test exhibited marked increases in Fos-LI in limbic cortical regions, lateral septum, medial amygdala and paraventricular nucleus of the hypothalamus (PVN). Uptake of 2-DG was increased by swim stress in some of the same brain regions where Fos-LI was induced, with the notable exception of a lack of a change in the PVN. Rats received injections for 3 wk with imipramine, desipramine, fluoxetine, nisoxetine, tranylcypromine or mianserin before being processed in the forced swim test. Chronic treatment with imipramine and desipramine alone induced Fos-LI in the central nucleus of the amygdala and the dorsolateral bed nucleus of the stria terminalis. After tranylcypromine treatment, Fos-LI was induced in many brain regions including limbic cortex, amygdala and paraventricular nucleus of the hypothalamus. None of the other antidepressants induced Fos-LI in any brain region examined. Chronic administration of imipramine, desipramine and nisoxetine antagonized the swim induced expression of Fos-LI in the PVN and in limbic cortical regions, including the medial prefrontal ventrolateral orbital and cingulate cortices. Chronic treatment with fluoxetine, tranylcypromine and mianserin did not alter swim stress-induced Fos-LI in any brain region. Thus, only antidepressant drugs that affect norepinephrine uptake (i.e., imipramine, desipramine and nisoxetine) antagonized swim stress-induced Fos-LI. In contrast to the action of chronic imipramine on Fos-LI induced by swim, chronic administration of imipramine did not antagonize the stress-induced changes in 2-DG uptake in limbic cortical regions. Acute administration of propranolol, which blocks beta-adrenergic receptors, reduced the number of cells staining for Fos-LI in limbic cortical regions, resembling the effects produced by chronic imipramine, desipramine and nisoxetine. In the PVN, neither propranolol nor prazosin (an alpha 1 antagonist) blocked the swim-induced Fos-LI, suggesting that swim-induced Fos-LI in the PVN is not under control of beta- or alpha 1-adrenergic receptors. These latter results imply that adaptation of noradrenergic receptors by chronic imipramine may not be related to the antagonism of stress-induced Fos-LI. The clear functional differences of the various antidepressant agents on swim stress-induced Fos-LI after chronic administration provide a functional classification of antidepressant drug action not previously identified.

Animals↗
PubMed1996

Discharging patients with prescriptions instead of medications: sequelae in a teaching hospital.

OBJECTIVE: This study measures the incidence of discrepancies among written prescriptions, medication regimens transcribed onto patient discharge instruction sheets (DCIs), and labels on medications dispensed by community pharmacies after discharge of patients from an academic medical center. METHODS: During a 2-month study period, we collected copies of prescriptions and DCIs. We also called care givers after discharge and asked them to read the medication labels that were filled from discharge prescriptions. Care givers were also asked whether they received instruction from community pharmacies. RESULTS: Data were collected on 335 prescriptions for 192 patients. Differences among the prescriptions, DCIs, and medication labels were found for 40 (12%) of the medications prescribed at discharge, representing 19% of the patients studied. Nineteen prescriptions had prescriber errors in dosing frequencies or dosage formulations. Three prescriptions were filled with different medication concentrations or strengths than requested. Prescriptions were altered by the community pharmacists for unexplained reasons in 6 cases, whereas the DCIs and original prescriptions differed in 12 cases. Only 44% of families were counseled about proper medication administration by their pharmacists. CONCLUSIONS: A potential for medication errors exists when pediatric patients are discharged with unfilled prescriptions. The potential may be worsened when discharge instructions are created from a prescription rather than from the label of a dispensed medication. Educational and risk-management efforts should emphasize the importance of writing complete, legible prescriptions and consulting appropriate reference materials to ensure that dose formulations and guidelines are accurate. Whenever possible, prescriptions should be filled before patients are discharged, so that the dispensed medications can be reviewed, and health care providers can provide accurate discharge instructions.

Academic Medical Centers↗