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Biomedical subjects

J A Espinosa

Publications and source records attributed to J A Espinosa.

15 recordsLinked to original sources
PubMed2004

Intraoperative human vagus nerve compound action potentials.

OBJECTIVE: Although electrical stimulation of vagus nerve is used widely for treatment of epilepsy the electrophysiological properties of human vagus nerve are not well characterized. Our objective was to measure compound action potentials of human vagus nerve fiber groups intraoperatively by stimulation using a commercially available generator and electrode system (Neurocybernetic Prosthesis System, NCP). MATERIAL AND METHODS: During NCP implantation we recorded compound action potentials evoked by stimulating the left vagus nerve through the NCP bipolar lead. Current intensities were varied from 0.25 to 3.0 mA. RESULTS: Vagus nerve compound action potential components conducting in the A, Adelta, and C velocity ranges could be elicited using either the NCP pulse generator or by a standard evoked potential instrument. A fiber potentials were recordable in all nerves, and were activated by very low stimulus currents. Adelta and C fibers were less reliably elicited, with C fibers requiring the highest currents. CONCLUSIONS: Three clearly identified fiber populations can be identified using therapeutic electrical stimulation of the human vagus. Intraoperative measurements of NCP-induced action potentials may potentially provide a marker for therapeutic stimulation and better insight into mechanisms of vagus nerve stimulation (VNS) efficacy.

Action Potentials↗
PubMed2000

Reducing errors made by emergency physicians in interpreting radiographs: longitudinal study.

OBJECTIVES: To reduce errors made in the interpretation of radiographs in an emergency department. DESIGN: Longitudinal study. SETTING: Hospital emergency department. INTERVENTIONS: All staff reviewed all clinically significant discrepancies at monthly meetings. A file of clinically significant errors was created; the file was used for teaching. Later a team redesigned the process. A system was developed for interpreting radiographs that would be followed regardless of the day of the week or time of day. All standard radiographs were brought directly to the emergency physician for immediate interpretation. Radiologists reviewed the films within 12 hours as a quality control measure, and if a significant misinterpretation was found patients were asked to return. MAIN OUTCOME MEASURES: Reduction in number of clinically significant errors (such as missed fractures or foreign bodies) on radiographs read in the emergency department. Data on the error rate for radiologists and the effect of the recall procedure were not available so reliability modelling was used to assess the effect of these on overall safety. RESULTS: After the initial improvements the rate of false negative errors fell from 3% (95% confidence interval 2.8% to 3.2%) to 1.2% (1.03% to 1.37%). After the processes were redesigned it fell further to 0.3% (0.26% to 0.34%). Reliability modelling showed that the number of potential adverse effects per 1000 cases fell from 19 before the improvements to 3 afterwards and unmitigated adverse effects fell from 2.2/1000 before to 0.16/1000 afterwards, assuming 95% success in calling patients back. CONCLUSION: Systems of radiograph interpretation that optimise the skills of all clinicians involved and contain reliable processes for mitigating errors can reduce error rates substantially.

Diagnostic Errors↗
PubMed2000

Delayed effects of pyridostigmine and exercise training on acetylcholinesterase and muscle tension in mouse lower extremity.

In this study, the interactive effects of pyridostigmine, a pretreatment drug against nerve agents, and exercise training on muscle tension were investigated in the mouse lower extremity anterior muscular compartment by dorsiflexion of the foot with stimulation of the peroneal nerve. Acetylcholinesterase (AChE), lipid peroxidation (in terms of the end-product malondialdehyde, MDA) and creatine phosphokinase (CPK) activity in the muscle were correlated with muscle tension. Male NIH Swiss mice were divided into four groups and treated as follows: (1) sedentary control; (2) pyridostigmine (1.2 mg/kg orally) daily for the 5th and 6th weeks; (3) exercise training for 10 weeks; and (4) pyridostigmine plus exercise training for 10 weeks. Experiments on muscle tension were conducted 4 weeks after the last dose of pyridostigmine or saline and 24 h after exercise. The muscle tension was measured in right and left legs using a tension transduction device connected to a polygraph. After muscle tension recording, mice were killed, blood and triceps muscle were isolated, and plasma CPK and muscle AChE activities, and MDA were determined. There was a significant increase in the muscle tension (P<0.05) in the group treated with pyridostigmine plus exercise as compared to the control and exercise groups. The pyridostigmine plus exercise group also showed a significant reduction in AChE activity (P<0.01) and enhanced MDA (P<0.05) in the triceps muscle. These results suggest that subchronic dosages of pyridostigmine and interaction with exercise training result in the delayed effects of reduction in muscle AChE activity and enhanced muscle tension.

Acetylcholinesterase↗
PubMed1998

Evidence of increased excitability in GEPR hippocampus preceding development of seizure susceptibility.

The genetically epilepsy-prone rat (GEPR) provides a valuable model to study the mechanism of neonatal seizure susceptibility because seizure predisposition in GEPRs is determined by factors present from birth. We have previously shown that reduced afterhyperpolarization (AHP), reduced spike frequency adaptation and increased excitation with repetitive stimulation are present in the adult GEPRs. To investigate whether these abnormalities are present at birth or appear at the time when GEPRs show seizure susceptibility and to elucidate whether these abnormalities were a consequence of seizure experience (the adult rats previously tested were induced to seize in three tests), we studied the membrane and synaptic properties of CA3 hippocampal neurons in preseizing offspring of GEPR-9s (seizure naive GEPRs). Electrophysiological recordings were done in the in vitro brain slice preparation during three different stages of early postnatal development (postnatal day (P) 7-10, P12-15 and P18-28) in GEPRs and compared to age matched control Sprague-Dawley (SD) rats. Reduction in AHP amplitude and duration and reduced inhibitory post synaptic potentials (IPSPs) were observed in the CA3 region in all the three stages tested. Reduction in spike frequency adaptation in 40% of CA3 neurons and reduction in fast AHP occurred in the 3rd and 4th weeks of postnatal development in GEPRs. Therefore, our results suggest that reduced synaptic inhibition and increased membrane excitability in the CA3 circuitry are present from early postnatal development and may represent few of the general cortical features that might eventually contribute to development of enhanced seizure susceptibility in developing GEPRs.

Action Potentials↗
PubMed1997

Impact on the care of the emergency department chest pain patient from the chest pain evaluation registry (CHEPER) study.

This study examines the question of whether chest pain observation units increase the proportion of chest pain patients with an extended evaluation for cardiac ischemia ("rule out myocardial infarction [MI] evaluation"), decrease the number of missed MIs, and decrease costs. This is a multiple site registry study of 8 established chest pain observation units (complying with the American College Emergency Physician's Observation Section's standards) compared with previous studies on chest pain evaluation without the use of observation (5 studies, 12,405 patients). A total of 23,407 of 444,189 emergency department patients (5.3%) had the chief complaint of chest pain during the study period. In the chest pain observation units, 153 of 2,229 patients (6.9%) with acute MI were identified. Most of the observation chest pain patients (76%) were discharged home without hospital admission. Compared to previous studies, a higher proportion of patients underwent a "rule out MI evaluation" (67%, 95% confidence interval [CI] 66%, 68% vs 57%, 95% CI 56%, 58%; p <0.001) equal to 2,250 additional patients completely evaluated ($1,219,500 additional costs). A lower proportion of MIs were missed (0.4%, 95% CI 0.3%, 0.5% vs 4.5%, 95% CI 4.0% to 5.5%; p <0.001) as estimated by return visits within 72 hours. Compared to previous studies, final hospital admission rate was lower (47%, 95% CI 46%, 48% vs 57%, 95% CI 56%, 58%; p <0.001), equal to 2,314 hospital admissions avoided in the study population ($4,093,466 saved costs). Calculated true costs overall were lower by $2,873,966 at the study hospitals. Thus, chest pain observation units increased the proportion of chest pain patients thoroughly evaluated with improved quality of care and lower costs.

Chest Pain↗
PubMed1997

A reengineering success story: process improvement in emergency department x-ray cycle time, leading to breakthrough performance in the ED ambulatory care (Fast Track) process.

This article describes the journey of a multidisciplinary reengineering team, which worked to reduce a critical, high-leverage process in an emergency department setting. The process selected was emergency department radiology services. This process was selected on a rational basis. The team knew tht 60 percent of our emergency department patients were truly ambulatory, and that most could be seen in a "fast track" process as part of our emergency department's core mission. However, we knew from customer satisfaction data, that patients would like to be "in and out" of emergency department Fast Track in less than an hour. Over half of our Fast Track patients require x-rays. For most, this was their sole reason for seeking emergency care. Our state, at the start of the project, included an average x-ray cycle time of over 60 minutes. The associated Fast-Track cycle time was over 90 minutes median. It was clear to the emergency department leadership, as well as to members of the Fast-Track management team, that a cycle time of 30 minutes or less for x-ray service was needed as a necessary condition to an hour or less Fast Track cycle time. It was also felt that a more rapid x-ray cycle time would allow for more rapid turn over of ED rooms, leading to a virtual greater capacity to the ED. It was hoped that this would lead to a reduction in the time from arrival to treatment by the emergency physician for all patients.

Ambulatory Care↗
PubMed1997

On lifting the fog of war in the battle on heart disease: Star Wars technology in pursuit of a seamless integration strategy.

In our efforts to reduce cardiac morbidity and mortality we often use terms such as the "battle" or "war" on heart disease. If we believe efforts to reduce cardiac disease are the moral equivalent of war, then perhaps we should explore ways that military strategic and tactical metaphors can be applied through technology to the cardiac battle. In this article we explore three major areas for technological advancement: adaptation of the strategies of outcomes management and evidence-based medicine, computer simulation and animation efforts to create horizontal and vertical integration of strategic efforts, and use of interactive multimedia in "recruiting an army" through community empowerment. The overall goal is to find ways to lift "the fog of war" in the battle on heart disease, in order to further the integration of our various efforts.

Cardiovascular Diseases↗
PubMed1995

Intractable partial epilepsy following low-dose scalp irradiation in infancy.

We report the development of intractable epilepsy in 3 patients treated with irradiation to "strawberry" scalp nevi in infancy. Low-dose radiation was used (12 and 13 Gy in 2 of the patients). The clinical evolution suggested a recognizable and distinctive postradiation syndrome. There was concordance between the site of radiation as shown by localized alopecia, the clinical features of the partial seizures, and electrographic abnormalities. The clinical picture was unlike delayed cerebral radiation necrosis of adulthood, which is not thought to occur at doses below 50 Gy, in 2-Gy fractions. Neurological deficits were not progressive and in 2 patients there was no evidence of parenchymal injury on cranial magnetic resonance imaging scanning. These differences suggest pathogenetic differences to cerebral radiation injury of adulthood, probably relating to the interaction between nervous system development, individual susceptibility, and the low doses of radiation employed.

Adolescent↗
PubMed1994

Unusual evolution and computerized tomographic appearance of a gliosarcoma.

A patient with a remote infarct, seizures, mild hemiparesis, and dysphasia became obtunded over four months and died. Computerized tomography (CT) over 5 years showed a consistent, large, wedge-shaped left hemisphere hypodensity with a central calcification, but without signs of mass effect. This was interpreted as an infarct of the left middle cerebral artery territory. Post-mortem examination of the brain revealed the entire area appearing as infarct on CT was a gliosarcoma. We suspect that the unusual CT appearance of the lesion was likely caused by multiple pathologies: a low grade glioma transforming into a gliosarcoma that was able to spread throughout the area of infarct encephalomalacia without revealing a typical CT appearance of mass effect. The patient's brief period of deterioration probably coincided with transformation of the tumor into a gliosarcoma. The variable CT characteristics of gliosarcomas are reviewed.

Brain Neoplasms↗
PubMed1993

Abducens palsy following shunting for hydrocephalus.

Over a period of 12 years, 80 patients underwent ventricular shunting for normal pressure hydrocephalus. Three developed sixth cranial nerve palsy in the first two weeks after surgery. This uncommon complication is usually transitory following the same pattern of abducens palsy after lumbar puncture or spinal anesthesia. Traction on the nerve with local ischemia has been involved as the responsible mechanism in both instances.

Abducens Nerve↗
PubMed1993

Dural arteriovenous malformations of the ethmoidal region: report of two cases.

Dural arteriovenous malformations of the ethmoidal region are extremely rare. They are usually supplied by the ipsilateral anterior ethmoidal artery with contralateral contribution in about half of the cases. They are characterized by a fistulous nidus within the dura, and their progression seems to involve a retrograde leptomeningeal vascular stasis with formation of varices and venous aneurysms. They have more propensity to rupture than dural malformations in other locations. Two patients who presented with an acute frontal hemorrhage are reported.

Cerebral Angiography↗
PubMed1992

Legal issues in emergency radiology. Practical strategies to reduce risk.

Various joint commission and individual state standards affect emergency radiology practice and have legal implications. The ACEP has entered the burgeoning field of practice guidelines; fortunately, their practice guideline preparation system is arguably the most thorough in medicine at this time. This is of great importance to emergency physicians, because practice guidelines are not without their own potential legal, educational, and compliance problems. Trends toward cost-reduction through reduced radiograph utilization are a real phenomenon in all of medicine. It remains to be seen if costs can be reduced without increasing legal exposure. Excellent clinical guidelines are helpful to emergency physicians. The Massachusetts ACEP model, which appears to effectively blend closed claim data into practice guidelines, has built-in educational support and compliance incentives. This model may become a national standard in the future. Pediatric radiology risk management issues, such as the statute of limitations, have been discussed. Emergency physicians should be knowledgeable about the most commonly missed pediatric emergency radiologic diagnoses. Some aspects of common emergency radiology practice patterns are of relevance to a discussion of risk management in emergency radiology. Issues such as emergency physician radiograph interpretation responsibilities and follow-up systems emerge repeatedly in malpractice claims. The use of CQI strategies may prove helpful in improving practice patterns. Communication between emergency physician and radiologists is critical. Good communication requires the development of good rapport and should pay dividends in improved patient care.

Adult↗
PubMedDate not supplied

The quality professional's expanding role as internal consultant: practical tips and survival strategies--Part 2.

Part 1 of this two-part article addressed the approach and skills needed to gain a clearly defined and agreed-upon direction for the consulting mission. The importance of mental preparation and flexibility was emphasized and a number of ethical dilemmas were reviewed, including confidentiality issues. Part 2 addresses strategies for handling difficult psychological issues that often come up in the process of internal consulting. Transference, resistance, regressions, and counterproductive group dynamics are reviewed. These psychological issues may be the predominant source of stress in an internal consulting experience. Case examples are presented along with some empowering strategies. It is hoped that through this review, the quality professional will be better prepared to meet the exciting and rewarding challenges of internal consulting.

Consultants↗
PubMedDate not supplied

The quality professional's expanding role as internal consultant: practical tips and survival strategies--Part I.

Expertise in quality and process improvement is becoming widely recognized as a valuable resource. The more objective viewpoint and experience of consulting firms or outside professionals in quality and change management often is critical to the success of organization-wide quality or change implementation. Outside consultants, however, are not inexpensive. It is predictable that there will be an increasing tendency for healthcare systems to look internally for organizational and quality expertise. Part one of this article discusses the approach and skills needed to gain a clearly defined and agreed-upon direction for the consulting mission. The importance of mental preparation and flexibility is discussed. Ethical dilemmas are a core challenge, and a number of real-life scenarios and associated strategies are presented.

Consultants↗