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Biomedical subjects

T A Schmidt

Publications and source records attributed to T A Schmidt.

At least 19 recordsLinked to original sources
PubMed1998

The stiffness of lumbar spinal motion segments with a high-intensity zone in the anulus fibrosus.

STUDY DESIGN: Biomechanical and anatomic study of human cadaveric spinal motion segments. OBJECTIVES: To measure the stiffness of spinal motion segments by disc type and by load type (flexion, extension, axial rotation, or lateral bending). To compare stiffness in motion segments with and without a high-intensity zone or radial tear in the anulus fibrosus. SUMMARY OF BACKGROUND DATA: The high-intensity zone, that is a linear zone of high-intensity on T2-weighted magnetic resonance images corresponding to a radial tear in the anulus fibrosus, is a marker for a painful disc at discography. The high-intensity zone is hypothetically associated with diminished stiffness of the motion segment. METHODS: Human cadaveric lumbar spinal motion segments with normal disc morphology or a high-intensity zone of the anulus fibrosus were selected on the basis of magnetic resonance imaging. The motion segments were subjected to incremental flexion, extension, rotation, and lateral bending torques. Rotation was measured with a kinematic system. Torque-rotation curves and stiffness were calculated for each motion segment and for each torque. The motion segments were sectioned on a cryomicrotome to verify the disc morphology as normal or as that of a radial tear. RESULTS: In four motion segments with normal discs, stiffness was greater in axial rotation (8.4 Nm/degree) than in lateral bending (2.3 Nm/degree), flexion (1.8 Nm/degree), or extension (2.6 Nm/degree). In 16 motion segments with a high-intensity zone, stiffness was 2.4 Nm/degree in axial rotation, and less severely reduced in lateral bending, flexion, and extension. Stiffness in motion segments with a high-intensity zone was significantly less with smaller than with larger axial rotation loads. CONCLUSIONS: The presence of a high-intensity zone in the intervertebral disc is associated with reduced stiffness of motion segments. The reduction is greater in axial rotation than in other torques. The reduction is more in smaller than in larger axial torques.

Aged↗
PubMed1998

Do patients refusing transport remember descriptions of risks after initial advanced life support assessment?

OBJECTIVE: To determine patient recall and understanding of instructions given to patients who refuse transport after initial paramedic assessment and medical treatment. METHODS: Following patient consent, a phone interview was completed for consecutive persons living in a large urban area for whom 9-1-1 was contacted but who subsequently refused transport after advanced life support (ALS) assessment. Subjects were asked about their recall of explained risks and benefits of transport, their understanding of those risks at the time of assessment, and subsequent use of medical care, including hospitalization. RESULTS: From October 1, 1996, to February 23, 1997, 324 people refused transport after ALS arrival. Sixty-eight people could not be contacted, providing a response rate of 79% (256/324). Six percent were subsequently admitted to the hospital for the same problem and an additional 59% sought care from a health care provider (66 ED visits, 63 personal physician, 16 urgent care, 5 other). There were no unexpected deaths. Ninety (35%) respondents were still experiencing symptoms at the time of phone contact. Despite the routine practice of providing a verbal explanation of risks and written instructions, only 141 (55%) recalled receiving written instructions and 56 (22%) recalled an explanation of risks. Twenty-six percent believed they did not fully understand their conditions or circumstances surrounding the 9-1-1 call when they refused transport and 18% would now take an ambulance if the same incident were to recur. CONCLUSION: A substantial proportion of patients refusing transport do not recall receiving verbal or written instructions and would reconsider their transport decision, raising doubts about people's ability to make informed decisions at a time of great vulnerability. The majority of patients accessed health care after refusing transport and 6% were hospitalized.

Emergency Medical Services↗
PubMed1998

Oregon emergency medical technicians' attitudes toward physician-assisted suicide.

OBJECTIVES: To determine Oregon intermediate and advanced emergency medical technicians' (EMTs') attitudes toward physician-assisted suicide (PAS) and factors associated with those attitudes. METHODS: An anonymous survey was sent to a random sample of 498 EMTs registered in Oregon. RESULTS: Surveys were delivered to 498 EMTs and 343 completed surveys were returned, for a response rate of 69%. The mean age of the respondents was 37.5 years (+/-8.73) and 79% were male. 232 (68%) agreed that PAS should be legal, 263 (77%) agreed that terminally ill people have a right to decide to commit suicide, while 57 (17%) thought not attempting resuscitation would be immoral. 251 (73%) reported seeing attempted suicide in terminally ill patients at least once, with 117 (34%) experiencing such calls >5 times. Only 22 (6%) stated that they would be unable to work in a system that directed them to withhold resuscitation after a PAS attempt, and 277 (81%) agreed that treatment protocols should direct EMTs to withhold resuscitation. 105 (31%) thought EMTs should participate in the decision to withhold resuscitation. 206 (60%) thought the law should allow lethal injection for terminally ill patients. 201 (59%) agreed there were circumstances under which they might personally consider PAS. If PAS were legal, EMTs stated they would withhold treatment from a terminally ill patient following attempted suicide in the following circumstances: based on standing orders, 78%; with on-line medical direction, 67%; after speaking with the primary physician, 53%; if the patient had decision-making capacity, 45%; with written documentation from the patient's physician, 68%; and never, 6%. CONCLUSIONS: A majority of Oregon EMTs responding to this survey expressed support for PAS, think treatment protocols should direct paramedics to withhold resuscitation in such cases, and would feel comfortable withholding resuscitation given appropriate protocols. Nearly 3 out of 4 Oregon EMTs report seeing at least 1 terminally ill patient who had attempted suicide.

Adult↗
PubMed1997

Multiple options and unique pathways: a new direction for EMS?

The same forces transforming the health care delivery system also are reshaping EMS. The changing economic and organizational structures of the health services delivery system may predict how EMS systems will redesign themselves. We discuss one template for future EMS systems.

Decision Support Techniques↗
PubMed1997

Reduced concentration of myocardial Na+,K(+)-ATPase in human aortic valve disease as well as of Na+,K(+)- and Ca(2+)-ATPase in rodents with hypertrophy.

Myocardial Na+,K(+)-ATPase was studied in patients with aortic valve disease, and myocardial Na+,K(+)- and Ca(2+)-ATPase were assessed in spontaneously hypertensive rats (SHR) and hereditary cardiomyopathic hamsters using methods ensuring high enzyme recovery. Na+,K(+)-ATPase was quantified by [3H]ouabain binding to intact myocardial biopsies from patients with aortic valve disease. Aortic stenosis, regurgitation and a combination hereof were compared with normal human heart and were associated with reductions of left ventricular [3H]ouabain binding site concentration (pmol/g wet weight) of 56, 46 and 60%, respectively (p < 0.01). Na+,K(+)- and Ca(2+)-ATPases were quantified by K(+)- and Ca(2+)-dependent p-nitrophenyl phosphatase (pNPPase) activity determinations in crude myocardial homogenates from SHR and hereditary cardiomyopathic hamsters. When SHR were compared to age-matched Wistar Kyoto (WKY) rats an increase in heart-body weight ratio of 75% (p < 0.001) was associated with reductions of K(+)- and Ca(2+)-dependent pNPPase activities (mumol/min/g wet weight) of 42 (p < 0.01) and 27% (p < 0.05), respectively. When hereditary cardiomyopathic hamsters were compared to age-matched Syrian hamsters an increase in heart-body weight ratio of 69% (p < 0.001) was found to be associated with reductions in K(+)- and Ca(2+)-dependent pNPPase activities of 50 (p < 0.001) and 26% (p = 0.05), respectively. The reductions in Na+,K(+)- and Ca(2+)-ATPases were selective in relation to overall protein content and were not merely the outcome of increased myocardial mass relative to Na+,K(+)- and Ca(2+)-pumps. In conclusion, myocardial hypertrophy is in patients associated with reduced Na+,K(+)-ATPase concentration and in rodents with reduced Na+,K(+)- and Ca(2+)-ATPase concentrations. This may be of importance for development of heart failure and arrhythmia in hypertrophic heart disease.

4-Nitrophenylphosphatase↗
PubMed1997

K+ supplementation increases muscle [Na+-K+-ATPase] and improves extrarenal K+ homeostasis in rats.

Effects of K+ supplementation (approximately 200 mmol KCl/100 g chow) on plasma K+, K+ content, and Na+-K+-adeonsinetriphosphatase (ATPase) concentration ([Na+-K+-ATPase]) in skeletal muscles as well as on extrarenal K+ clearance were evaluated in rats. After 2 days of K+ supplementation, hyperkalemia prevailed (K+-supplemented vs. weight-matched control animals) [5.1 +/- 0.2 (SE) vs. 3.2 +/- 0.1 mmol/l, P < 0.05, n = 5-6], and after 4 days a significant increase in K+ content was observed in gastrocnemius muscle (104 +/- 2 vs. 97 +/- 1 micromol/g wet wt, P < 0.05, n = 5-6). After 7 days of K+ supplementation, a significant increase in [3H] ouabain binding site concentration (344 +/- 5 vs. 239 +/- 8 pmol/g wet wt, P < 0.05, n = 4) was observed in gastrocnemius muscle. After 2 wk, increases in plasma K+, K+ content, and [3H]ouabain binding site concentration in gastrocnemius muscle amounted to 40, 8, and 68% (P < 0.05) above values observed in weight-matched control animals, respectively. The latter change was confirmed by K+-dependent p-nitrophenyl phosphatase activity measurements. Fasting for 1 day reduced plasma K+ and K+ content in gastrocnemius muscle in rats that had been K+ supplemented for 2 wk by 3.1 +/- 0.3 mmol/l (P < 0.05, n = 5) and 15 +/- 2 micromol/g wet wt (P < 0.05, n = 5), respectively. After induction of anesthesia, arterial plasma K+ was measured during intravenous KCl infusion (0.75 mmol KCl x 100 g body wt(-1) x h(-1)). The K+-supplemented fasted group demonstrated a 42% (P < 0.05) lower plasma K+ rise, associated with a significantly higher increase in K+ content in gastrocnemius muscle of 7 micromol/g wet wt (P < 0.05, n = 5) compared with their control animals. In conclusion, K+ supplementation increases plasma K+, K+ content, and [Na+-K+-ATPase] in skeletal muscles and improves extrarenal K+ clearance capacity.

Animals↗
PubMed1997

Lumbar facet joint tropism does not accelerate degeneration of the facet joints.

PURPOSE: To study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration. METHODS: The orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration. RESULTS: We identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level. CONCLUSION: Age, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism.

Adult↗
PubMed1996

Legalizing assisted suicide--views of physicians in Oregon.

BACKGROUND: Since the Oregon Death with Dignity Act was passed in November 1994, physicians in Oregon have faced the prospect of legalized physician-assisted suicide. We studied the attitudes and current practices of Oregon physicians in relation to assisted suicide. METHODS: From March to June 1995, we conducted a cross-sectional mailed survey of all physicians who might be eligible to prescribe a lethal dose of medication if the Oregon law is upheld. Physicians were asked to complete and return a confidential 56-item questionnaire. RESULTS: Of the 3944 eligible physicians who received the questionnaire, 2761 (70 percent) responded. Sixty percent of the respondents thought physician-assisted suicide should be legal in some cases, and nearly half (46 percent) might be willing to prescribe a lethal dose of medication if it were legal to do so; 31 percent of the respondents would be unwilling to do so on moral grounds. Twenty-one percent of the respondents have previously received requests for assisted suicide, and 7 percent have complied. Half the respondents were not sure what to prescribe for this purpose, and 83 percent cited financial pressure as a possible reason for such requests. The respondents also expressed concern about complications of suicide attempts and doubts about their ability to predict survival at six months accurately. CONCLUSIONS: Oregon physicians have a more favorable attitude toward legalized physician-assisted suicide, are more willing to participate, and are currently participating in greater numbers than other surveyed groups of physicians in the United States. A sizable minority of physicians in Oregon objects to legalization and participation on moral grounds. Regardless of their attitudes, physicians had a number of reservations about the practical applications of the act.

Adult↗
PubMed1996

Reduction of cerebral cortical [3H]ouabain binding site (Na+,K(+)-ATPase) density in dementia as evaluated in fresh human cerebral cortical biopsies.

Na+,K(+)-ATPase density in human cerebral cortex was for the first time studied by vanadate facilitated [3H]ouabain binding to intact samples. Fresh human cerebral cortical biopsies were obtained as a result of diagnostic frontal lobe biopsy from patients with normal pressure hydrocephalus (NPH) syndrome and associated dementia. For control measurements post-mortem samples were obtained from patients without clinically observed dementia. [3H]ouabain binding kinetics were evaluated: when incubating samples in 1 microM [3H]ouabain binding equilibrium was obtained after 6 h of incubation, non-specific uptake and retention amounted to only 2.3% of total uptake and retention of [3H]ouabain and release of specifically bound [3H]ouabain during washout in the cold occurred only slowly (T1/2 = 37 h). Evaluation of receptor affinity for ouabain was in agreement with a heterogeneous population of [3H]ouabain binding sites. [3H]Ouabain binding was significantly reduced after frozen storage of samples before measurements. Post-mortem degradation of cerebral [3H]ouabain binding sites occurred only slowly (T1/2 = 75 h). No significant variation in [3H]ouabain binding site density was observed between the cerebral lobes with occipital, parietal and temporal values (means +/- S.E.M., n = 5) amounting to 10281 +/- 649, 11267 +/- 1011 and 9263 +/- 615 pmol/g wet wt., respectively. [3H]Ouabain binding measured in frontal cortical samples gave values of (means +/- S.E.M., n = 5) 4274 +/- 1020 and 11397 +/- 976 pmol/g wet wt. delta % = 62; P < 0.05) in patients with dementia and controls, respectively. Human cerebral cortical capacity for active K+ uptake was around 37- and 16-fold greater than in skeletal muscular and myocardial tissue, respectively.

Aged↗
PubMed1996

A method to communicate patient preferences about medically indicated life-sustaining treatment in the out-of-hospital setting.

OBJECTIVE: Patient preferences for life-sustaining treatment are frequently unknown at critical moments, which often results in clinicians providing treatment that is not medically indicated and/or may not be consistent with patient desires. A consortium of Oregon health care professionals developed the Medical Treatment Coversheet (MTC) to standardize documentation of patient preferences in the out-of-hospital setting by having corresponding physician orders available at the patient's location. We describe a unique process of development, evaluation, and implementation of the MTC. DESIGN: First, we conducted focus groups of providers to help draft the MTC. Second, the accuracy of MTC interpretation was determined by cohorts of acute and long-term care providers by indicating their treatment approach to three hypothetical written scenarios. They responded to the same scenarios twice, with and without the MTC. Responses were compared with each other and with ideal responses (most medically appropriate and in agreement with patient preferences) as defined by an expert panel. Finally, we are instituting pilot projects and developing a plan for statewide voluntary implementation of the MTC. SETTING: Urban and rural long-term care facilities and emergency medical service systems in Oregon. PARTICIPANTS: Focus groups included 28 general internists practicing in urban and rural settings and five nurses working in a long-term care facility. In addition, 87 providers (19 primary care physicians, 20 emergency physicians, 26 paramedics, and 22 long-term care nurses) participated in the evaluation of the form by responding to hypothetical scenarios. Providers in long-term care facilities in both an urban and rural area helped with pilot implementation of the MTC. Use of the MTC in noninstitutional settings was not evaluated. MAIN OUTCOME MEASURES: Suggestions from focus groups were incorporated into the form. For the hypothetical scenario responses, ideal appropriateness scores were analyzed, with a total possible score of 30 for each acute care provider and 15 for each long-term care provider. Statistically significant differences were determined using a paired t test. We report the experience of providers who helped with the pilot implementation of the form. RESULTS: Focus groups would use the MTC and believed it would be useful for their patients. Comparing responses to the hypothetical scenarios without the MTC to those with the MTC, 37% of treatment decisions changed for acute care and 29% changed for long-term care providers. Changes were attributable overwhelmingly to withholding treatments consistent with patient preferences. Compared with the ideal, decisions were more appropriate for all specific treatments across all scenarios and clinician groups with the MTC, with one exception: some advanced emergency treatments were withheld inappropriately by 18% of acute care providers with the MTC, (chi-square = 15.94, P < .0001). For all scenarios combined, appropriateness scores increased significantly with the MTC for both acute care (16.4 to 22.3, P < .0001) and long-term care providers (8.8 to 12.2, P < .0001). Overall, providers helping with the pilot implementation were satisfied with the document, organizational endorsements, and available informational resources. CONCLUSION: We describe our process for development, initial evaluation, and implementation of the MTC. In clinical scenarios overall, the MTC improves the appropriateness of clinicians' decisions about life-sustaining treatments. We are planning statewide implementation of the MTC after appropriate education of clinicians.

Advance Care Planning↗
PubMed1996

Oregon emergency physicians' experiences with, attitudes toward, and concerns about physician-assisted suicide.

OBJECTIVE: To determine emergency physicians' (EPs') attitudes toward physician-assisted suicide (PAS), factors associated with those attitudes, current experiences with attempted suicides in terminally ill persons, and concerns about the impact of legalizing PAS on emergency medicine practice. METHODS: A cross-sectional, anonymous mailed survey was taken of EPs in the state of Oregon. RESULTS: Of 356 eligible physicians, 248 (70%) returned the survey. Of the respondents, 69% indicated that PAS should be legal, 65% considered PAS consistent with the physician's role, and 19% believed that it is immoral. The respondents were concerned that patients might feel pressure if they perceived themselves to be either a care burden on others (82%) or a financial stress to others (69%). Only 37% indicated that the Oregon initiative has enough safeguards to protect vulnerable persons. Support for legalization was not associated with gender, age, or practice location. Respondents with no religious affiliation were most supportive of PAS (p < 0.001), and Catholic respondents were least suppportive (p = 0.03). A majority (58%) had treated at least 1 terminally ill patient after an apparent overdose. Most respondents (97%) indicated at least 1 circumstance for which they would sometimes be willing to let a terminally ill patient die without resuscitation after PAS if the Oregon initiative becomes law: if verified with an advance directive from the patient (81%), with documentation in writing from the physician (73%), after speaking to the primary physician (64%), if a competent patient verbally confirmed intent (60%), or if the family verbally confirmed intent (52%). CONCLUSIONS: Although the majority of Oregon EPs favor the concept of legalization of PAS, most have concerns that safeguards in the Oregon initiative are inadequate to protect vulnerable patients. These physicians would consider not resuscitating terminally ill patients who have attempted suicide under the law's provisions, only in the setting of documentation of the patient's intent.

Adult↗
PubMed1996

Occult lumbar lateral spinal stenosis in neural foramina subjected to physiologic loading.

PURPOSE: To measure the effect of extension, flexion, lateral bending, and axial rotation loads applied to the spine on the anatomic relationship of the spinal nerves in the neural foramen to the ligamentum flavum and the intervertebral disk, anc to determine the effect of disk degeneration on the response to loading. METHODS: Cadaveric lumbar motion segments were examined with CT and MR imaging, loaded with pure moment forces, frozen in situ, reexamined with CT, and sectioned with a cryomicrotome. The morphology of the intervertebral disks was classified on the basis of the appearance of the cryomicrotome sections. The neural foramina were classified as having no evident stenosis, as being stenotic, as having occult stenosis, or as showing resolved stenosis on the basis of the images and sections before and after loading. The stenotic and nonstenotic foramina were stratified by disk level, intervertebral disk classification, and type of loading applied. The effect of spinal level, disk type, and load type on the prevalence of stenosis was studied. RESULTS: On average, extension, flexion, lateral bending, and axial rotation resulted in the ligamentum flavum or intervertebral disk contacting or compressing the spinal nerve in 18% of the neural foramina. Extension loading produced the most cases of nerve root contact, and lateral bending produced the fewest cases. Each of the loading types resulted also in diminished contact between the spinal nerve and the intervertebral disk or ligamentum flavum in some cases. Disk degeneration significantly increased the prevalence of spinal stenosis. All foramina associated with advanced disk degeneration and half of the foramina associated with disks having radial tears of the annulus fibrosus either developed occult stenosis or were stenotic before loading. CONCLUSIONS: The study supports the concept of dynamic spinal stenosis; that is, intermittent stenosis of the neural foramina. Flexion, extension, lateral bending, and axial rotation significantly changed the anatomic relationships of the ligamentum flavum and intervertebral disk to the spinal nerve roots.

Adult↗