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1.
JAMA Netw Open ; 6(8): e2329991, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37603335

RESUMO

Importance: Reducing Medicare expenditures is a key objective of Medicare's transition to value-based reimbursement models. Improving access to primary care is an important way to reduce expenditures, yet less is known about how visits should be organized to maximize savings. Objective: To examine the association between Medicare savings and primary care visit patterns. Design, Setting, and Participants: This retrospective cohort study used data from a 5% sample of traditional Medicare claims from 2016 to 2019. Participants had at least 3 primary care visits with at least 180 days between the first and the last visit, were not enrolled in Medicare Advantage, did not have end-stage kidney disease, and were not institutionalized. Data were analyzed from June 2022 to April 2023. Exposures: Primary care visit patterns: visit frequency, regularity, continuity of care. Main Outcomes and Measures: Savings in Medicare expenditures; risk-adjusted Medicare expenditures, number of emergency department (ED) visits, and hospitalizations. Results: Among 504 471 beneficiaries (298 422 [59.16%] women; mean [SD] age, 74.26 [10.41] years), temporally regular visits with higher continuity were associated with the highest savings. For these patients, the savings increased with increasing visit frequencies, with peak savings observed at higher visit frequencies as clinical complexity increased. As regularity and continuity decreased, the association between savings and visit frequencies progressively inverted. The group with a regular and highly continuous pattern was associated with greater savings (175.87%; 95% CI, 167.40% to 184.33%; P < .001), lower risk-adjusted expenditures (-16.61%; 95% CI, -16.73% to -16.48%; P < .001), fewer risk-adjusted ED visits (-40.49%; 95% CI, -40.55% to -40.43%; P < .001), and fewer risk-adjusted hospitalizations (-53.32%; 95% CI, -53.49% to -53.14%; P < .001) compared with the irregular noncontinuous group. Conclusions and Relevance: In this cohort study, savings in Medicare expenditures and improvements in acute care utilization were associated with visit frequency, regularity, and continuity in primary care in an interrelated fashion such that optimization of primary care visit patterns along each axis were associated with the largest improvement in outcomes. Demonstrating the magnitude and interdependence of these associations is useful for health care professionals and policymakers as Medicare continues its transition to value-based reimbursement models.


Assuntos
Continuidade da Assistência ao Paciente , Medicare , Estados Unidos , Humanos , Idoso , Feminino , Masculino , Estudos de Coortes , Estudos Retrospectivos , Cuidados Críticos
2.
Addict Sci Clin Pract ; 18(1): 38, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-37264449

RESUMO

BACKGROUND: Hospitalizations are a vital opportunity for the initiation of life-saving opioid agonist therapy (OAT) for patients with opioid use disorder. A novel approach to OAT initiation is the use of IV buprenorphine for low dose induction, which allows patients to immediately start buprenorphine at any point in a hospitalization without stopping full agonist opioids or experiencing significant withdrawal. METHODS: This is a retrospective case series of 33 patients with opioid use disorder concurrently treated with full agonist opioids for pain who voluntarily underwent low dose induction at a tertiary academic medical center. Low dose induction is the process of initiating very low doses of buprenorphine at fixed intervals with gradual dose increases in patients who recently received or are simultaneously treated with full opioid agonists. Our study reports one primary outcome: successful completion of the low dose induction (i.e. transitioned from low dose IV buprenorphine to sublingual buprenorphine-naloxone) and three secondary outcomes: discharge from the hospital with buprenorphine-naloxone prescription, self-reported pain scores, and nursing-assessed clinical opiate withdrawal scale (COWS) scores over a 6-day period, using descriptive statistics. COWS and pain scores were obtained from day 0 (prior to starting the low dose induction) to day 5 to assess the effect on withdrawal symptoms and pain control. RESULTS: Thirty patients completed the low dose induction (30/33, 90.9%). Thirty patients (30/33, 90.9%) were discharged with a buprenorphine prescription. Pain and COWS scores remained stable over the course of the study period. Mean COWS scores for all patients were 2.6 (SD 2.8) on day 0 and 1.6 (SD 2.6) on day 5. Mean pain scores for all patients were 4.4 (SD 2.1) on day 0 and 3.5 on day 5 (SD 2.1). CONCLUSIONS: This study found that an IV buprenorphine low dose induction protocol was well-tolerated by a group of 33 hospitalized patients with opioid use disorder with co-occurring pain requiring full agonist opioid therapy. COWS and pain scores improved for the majority of patients. This is the first case series to report mean daily COWS and pain scores over an extended period throughout a low dose induction process.


Assuntos
Buprenorfina , Transtornos Relacionados ao Uso de Opioides , Humanos , Buprenorfina/uso terapêutico , Analgésicos Opioides/uso terapêutico , Combinação Buprenorfina e Naloxona/uso terapêutico , Estudos Retrospectivos , Tratamento de Substituição de Opiáceos/métodos , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Dor/tratamento farmacológico , Dor/induzido quimicamente
3.
JAMA ; 329(20): 1789-1790, 2023 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-37093596

RESUMO

This JAMA Clinical Guidelines Synopsis summarizes the Centers for Disease Control and Prevention's 2022 clinical practice guideline for prescribing opioids for pain.


Assuntos
Analgésicos Opioides , Dor Crônica , Padrões de Prática Médica , Humanos , Analgésicos Opioides/uso terapêutico , Dor Crônica/tratamento farmacológico , Prescrições de Medicamentos , Estados Unidos , Dor/tratamento farmacológico
4.
J Trauma Acute Care Surg ; 95(2): 226-233, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-36914601

RESUMO

BACKGROUND: Opioid use disorder (OUD) is common in the hospitalized trauma population, being a comorbid diagnosis in approximately 1% of operative trauma cases. The impact of an addiction consult service in this population has been less well studied but may lead to increased provision of evidence-based OUD treatment and improved postdischarge outcomes. METHODS: One hundred thirteen patients with an International Classification of Diseases diagnosis of OUD who were admitted to the trauma service at a single academic hospital between January 2020 to December 2021 were included in a retrospective chart review. Wilcoxon rank-sum tests were used to evaluate differences between patients who received an OUD consult and those who did not. Regression analysis was used to assess differences in postdischarge acute care utilization, attendance of follow-up appointments, initiation of and discharge on medication for opioid use disorder (MOUD), naloxone prescribing at discharge, and length of stay (LOS) between the consult and no-consult groups. RESULTS: Eighty-one patients in the study population received a consult and 32 did not. Patients in the consult group were more likely to have started MOUD during their admission (odds ratio [OR], 2.09; p < 0.001), be discharged with naloxone (OR, 1.89; p < 0.001), have a plan in place for continued OUD treatment at discharge (OR, 1.43; p < 0.001), and attend scheduled follow-up appointments with the trauma team (OR, 1.76; p = 0.02). Differences in acute care utilization and LOS between the two groups were not statistically significant. CONCLUSION: An OUD consult service can provide benefit to hospitalized trauma patients by increasing likelihood of starting MOUD, of discharging with MOUD and naloxone, and of attending trauma follow-up appointments without increasing LOS or acute care utilization. Thus, addiction consult service interventions during hospital admissions for trauma may serve to facilitate both evidence-based OUD care and posthospitalization trauma care. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.


Assuntos
Assistência ao Convalescente , Transtornos Relacionados ao Uso de Opioides , Humanos , Alta do Paciente , Estudos Retrospectivos , Transtornos Relacionados ao Uso de Opioides/diagnóstico , Transtornos Relacionados ao Uso de Opioides/terapia , Naloxona , Analgésicos Opioides
5.
Acad Med ; 98(6S): S25-S27, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36811966

RESUMO

PROBLEM: Opioid-related morbidity and mortality continues to accelerate, with increasing acute care events for opioid-related causes. Most patients do not receive evidence-based treatment for opioid use disorder (OUD) during acute hospitalizations despite this being an invaluable moment to initiate substance use treatment. Inpatient addiction consult services can bridge this gap and improve patient engagement and outcomes, but varying models and approaches are needed to match institutional resources. APPROACH: To improve care for hospitalized patients with OUD, a work group was formed at the University of Chicago Medical Center in October 2019. An OUD consult service, run by generalists, was created as part of a series of process improvement interventions. Important collaborations with pharmacy, informatics, nursing, physicians, and community partners have occurred over the last 3 years. OUTCOMES: The OUD consult service completes 40-60 new inpatient consults monthly. Between August 2019 and February 2022, the service completed 867 consults from across the institution. Most consult patients were started on medications for opioid use disorder (MOUD), and many received MOUD and naloxone at discharge. Patients who were treated by our consult service experienced lower 30-day and 90-day readmission rates compared with patients who did not receive a consult. Length of stay for patients receiving a consult was not increased. NEXT STEPS: Adaptable models of hospital-based addiction care are needed to improve care for hospitalized patients with OUD. Continued work to reach a higher percentage of hospitalized patients with OUD and to improve linkage to care with community collaborators are important steps to strengthen the care received by individuals with OUD in all clinical departments.


Assuntos
Transtornos Relacionados ao Uso de Opioides , Médicos , Humanos , Analgésicos Opioides/uso terapêutico , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Hospitalização , Pacientes Internados
6.
J Am Pharm Assoc (2003) ; 63(1): 204-211.e2, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36115762

RESUMO

BACKGROUND: Hospitalized patients with opioid use disorder (OUD) present unique challenges and opportunities for inpatient medical teams. Having the ability to initiate medications for opioid use disorder (MOUD) and linkage to outpatient treatment are key to improve inpatient care of patients with OUD. OBJECTIVE: This study aimed to describe the process taken by a multidisciplinary work group to improve the acute care management of patients with OUD. PRACTICE DESCRIPTION: In 2018, we identified that inpatient care teams at the University of Chicago Medicine (UCM) lacked a standardized approach to the management of hospitalized patients with OUD and that the care typically did not include evidence-based therapies. Herein, we describe the process taken to develop the OUD workgroup and the work completed by the workgroup. PRACTICE INNOVATION: The OUD workgroup spearheaded the development of an OUD consult service, formulary revisions, education for health care workers (inpatient nurse training and X-waiver training for prescribers), and outpatient partnerships. Pharmacy-led initiatives included formulary management, electronic medication orders, naloxone co-prescribing decision support, and MOUD education. EVALUATION METHODS: The OUD consult service was granted an Institutional Review Board exemption for quality improvement analysis through UCM. A data analytics dashboard was built to track consult service volumes and outcomes. RESULTS: From July 2020 to April 2021, 296 OUD consults occurred. In total, 103 consult patients (35%) received and were discharged with buprenorphine. An additional 118 patients (40%) were managed with methadone and linked to outpatient care. Naloxone dispensing at discharge increased to over 65%, which did not include patients who opted out or were discharged to a facility. CONCLUSION: The ongoing OUD epidemic presents a need for the development of services to improve management of patients with OUD in the acute care setting. The OUD workgroup has improved the management of patients admitted with OUD. Pharmacy-based initiatives are key to the development of safe and effective management of OUD in hospitalized patients.


Assuntos
Buprenorfina , Transtornos Relacionados ao Uso de Opioides , Humanos , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Buprenorfina/uso terapêutico , Metadona/uso terapêutico , Hospitalização , Naloxona/uso terapêutico , Analgésicos Opioides/efeitos adversos , Tratamento de Substituição de Opiáceos
7.
JAMA Netw Open ; 5(8): e2229504, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-36044213

RESUMO

Importance: Time-based billing options for physicians have expanded, enabling many physicians to bill according to time spent instead of medical decision-making (MDM) level for fee-for-service outpatient visits. However, no study to date has estimated the revenue changes associated with time-based billing. Objective: To compare evaluation and management (E/M) reimbursement for physicians using time-based billing vs MDM-based billing for outpatient visits of varying lengths. Design, Setting, and Participants: This economic evaluation used 2019 billing data for outpatient E/M codes and 2021 reimbursement rates from the Centers for Medicare & Medicaid Services. Modeling of generic clinic templates was performed to estimate expected yearly E/M revenues for a single full-time physician working in an outpatient clinic using fee-for-service billing. Main Outcomes and Measures: Yearly E/M revenues for different patient visit templates were modeled. The standardized length of return patient visits was 10 to 45 minutes, and new patient visits were twice as long in duration. Results: Under MDM-based billing, increased visit length was associated with decreased E/M revenue ($564 188 for 30-minute new patient visit/15-minute return patient visit vs $423 137 for 40-minute new patient visit/20-minute return patient visit). Under time-based billing, yearly E/M revenue remained similar across increasing visit lengths ($400 432 for 30-minute new patient visit/15-minute return patient visit vs $458 718 for 40-minute new patient visit/20-minute return patient visit). Compared with time-based billing, MDM-based billing was associated with higher E/M revenue for 10- to 15-minute return patient visits ($400 432 vs $564 188). Time-based billing was associated with higher E/M revenue for return patient visits lasting 20 minutes or longer. The highest modeled E/M revenue of $846 273 occurred for 10-minute return patient visits under MDM-based billing. Conclusions and Relevance: Results of this study showed that the relative economic benefits of MDM-based billing and time-based billing differed and were associated with the length of patient visits. Physicians with longer patient visits were more likely to experience revenue increases from using time-based billing than physicians with shorter patient visits.


Assuntos
Pacientes Ambulatoriais , Médicos , Idoso , Instituições de Assistência Ambulatorial , Planos de Pagamento por Serviço Prestado , Humanos , Medicare , Estados Unidos
8.
Health Aff (Millwood) ; 41(7): 980-984, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35759703

RESUMO

Diabetes process and outcome measures are common quality measures in payment reform models, including Alternative Payment Models (APMs) and value-based insurance design (VBID). In this commentary we review evidence from selected research to examine whether these payment models can improve the value of diabetes care. We found that higher-risk APMs yielded greater improvements in diabetes process measures than lower-risk APMs, and that VBID models appeared to improve medication adherence but not other quality measures. We argue that these models are promising first steps in redesigning the payment system to improve diabetes care. However, greater coordination and alignment across models is needed to enhance their impact on providers' behavior, diabetes care processes, and patient health outcomes.


Assuntos
Diabetes Mellitus , Seguro de Saúde Baseado em Valor , Diabetes Mellitus/terapia , Humanos , Estados Unidos
9.
JMIR Hum Factors ; 8(3): e29690, 2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34184994

RESUMO

BACKGROUND: Since the COVID-19 pandemic onset, telemedicine has increased exponentially across numerous outpatient departments and specialties. Qualitative studies examining clinician telemedicine perspectives during the pandemic identified challenges with physical examination, workflow concerns, burnout, and reduced personal connection with patients. However, these studies only included a relatively small number of physicians or were limited to a single specialty, and few assessed perspectives on integrating trainees into workflows, an important area to address to support the clinical learning environment. As telemedicine use continues, it is necessary to understand a range of clinician perspectives. OBJECTIVE: This study aims to survey pediatric and adult medicine clinicians at the University of Chicago Medical Center to understand their telemedicine benefits and barriers, workflow impacts, and training and support needs. METHODS: In July 2020, we conducted an observational cross-sectional study of University of Chicago Medical Center faculty and advanced practice providers in the Department of Medicine (DOM) and Department of Pediatrics (DOP). RESULTS: The overall response rate was 39% (200/517; DOM: 135/325, 42%; DOP: 65/192, 34%); most respondents were physicians (DOM: 100/135, 74%; DOP: 51/65, 79%). One-third took longer to prepare for (65/200, 33%) and conduct (62/200, 32%) video visits compared to in-person visits. Male clinicians reported conducting a higher percentage of telemedicine visits by video than their female counterparts (P=.02), with no differences in the number of half-days per week providing direct outpatient care or supervising trainees. Further, clinicians who conducted a higher percentage of their telemedicine by video were less likely to feel overwhelmed (P=.02), with no difference in reported burnout. Female clinicians were "more overwhelmed" with video visits compared to males (41/130, 32% vs 12/64, 19%; P=.05). Clinicians 50 years or older were "less overwhelmed" than those younger than 50 years (30/85, 35% vs 23/113, 20%; P=.02). Those who received more video visit training modalities (eg, a document and webinar on technical issues) were less likely to feel overwhelmed by the conversion to video visits (P=.007) or burnt out (P=.009). In addition, those reporting a higher ability to technically navigate a video visit were also less likely to feel overwhelmed by video visits (P=.02) or burnt out (P=.001). The top telemedicine barriers were patient-related: lack of technology access, lack of skill, and reluctance. Training needs to be focused on integrating learners into workflows. Open-ended responses highlighted a need for increased support staff. Overall, more than half "enjoyed conducting video visits" (119/200, 60%) and wanted to continue using video visits in the future (150/200, 75%). CONCLUSIONS: Despite positive telemedicine experiences, more support to facilitate video visits for patients and clinicians is needed. Further, clinicians need additional training on trainee education and integration into workflows. Further work is needed to better understand why gender and age differences exist. In conclusion, interventions to address clinician and patient barriers, and enhance clinician training are needed to support telemedicine's durability.

10.
JMIR Med Educ ; 7(2): e29099, 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33878011

RESUMO

The COVID-19 pandemic has pushed telemedicine to the forefront of health care delivery, and for many clinicians, virtual visits are the new normal. Although telemedicine has allowed clinicians to safely care for patients from a distance during the current pandemic, its rapid adoption has outpaced clinician training and development of best practices. Additionally, telemedicine has pulled trainees into a new virtual education environment that finds them oftentimes physically separated from their preceptors. Medical educators are challenged with figuring out how to integrate learners into virtual workflows while teaching and providing patient-centered virtual care. In this viewpoint, we review principles of patient-centered care in the in-person setting, explore the concept of patient-centered virtual care, and advocate for the development and implementation of patient-centered telemedicine competencies. We also recommend strategies for teaching patient-centered virtual care, integrating trainees into virtual workflows, and developing telemedicine curricula for graduate medical education trainees by using our TELEMEDS framework as a model.

12.
Clin Diabetes ; 35(3): 168-170, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28761219

RESUMO

In Brief "Quality Improvement Success Stories" are published by the American Diabetes Association in collaboration with the American College of Physicians, Inc., and the National Diabetes Education Program. This series is intended to highlight best practices and strategies from programs and clinics that have successfully improved the quality of care for people with diabetes or related conditions. Each article in the series is reviewed and follows a standard format developed by the editors of Clinical Diabetes. The following article describes a successful project by faculty at the University of Chicago to improve blood pressure control among hypertensive patients at a general internal medicine clinic on the South Side of Chicago, Ill.

13.
Am Fam Physician ; 94(6): 463-9, 2016 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-27637122

RESUMO

Pulmonary hypertension is a common, complex group of disorders that result from different pathophysiologic mechanisms but are all defined by a mean pulmonary arterial pressure of 25 mm Hg or greater. Patients often initially present to family physicians; however, because the symptoms are typically nonspecific or easily attributable to comorbid conditions, diagnosis can be challenging and requires a stepwise evaluation. There is limited evidence to support screening of asymptomatic individuals. Echocardiography is recommended as the initial step in the evaluation of patients with suspected pulmonary hypertension. A definitive diagnosis cannot be made on echocardiographic abnormalities alone, and some patients require invasive evaluation by right heart catheterization. For certain categories of pulmonary hypertension, particularly pulmonary arterial hypertension, treatment options are rapidly evolving, and early diagnosis and prompt referral to an expert center are critical to ensure the best prognosis. There are no directed therapies for many other categories of pulmonary hypertension; therefore, family physicians have a central role in managing contributing comorbidities. Other important considerations for patients with pulmonary hypertension include influenza and pneumonia immunizations, contraception counseling, preoperative assessment, and mental health.


Assuntos
Hipertensão Pulmonar/diagnóstico , Hipertensão Pulmonar/terapia , Eletrocardiografia , Humanos , Hipertensão Pulmonar/fisiopatologia , Guias de Prática Clínica como Assunto
14.
Obstet Gynecol Clin North Am ; 43(2): 287-306, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27212093

RESUMO

Hypertension is the most commonly encountered chronic medical condition in primary care and one of the most significant modifiable cardiovascular risk factors for women and men. Timely diagnosis and evidence-based management offer an important opportunity to reduce the risk of hypertension-related morbidity and mortality, including cardiovascular events, end-stage renal disease, and heart failure. Clinical trials have shown significant improvements in patient-oriented outcomes when hypertension is well-controlled, yet many hypertensive patients remain undiagnosed, uncontrolled, or managed with inappropriate pharmacotherapy. This article discusses the initial diagnosis, evaluation, and management of hypertension in nonpregnant women, with topics for obstetrician-gynecologists and women's health providers.


Assuntos
Anti-Hipertensivos/uso terapêutico , Doenças Cardiovasculares/prevenção & controle , Terapia de Reposição Hormonal/efeitos adversos , Hipertensão/prevenção & controle , Obesidade/prevenção & controle , Atenção Primária à Saúde , Saúde da Mulher , Fatores Etários , Doenças Cardiovasculares/epidemiologia , Feminino , Humanos , Hipertensão/etiologia , Obesidade/complicações , Obesidade/epidemiologia , Fatores de Risco , Estados Unidos/epidemiologia
16.
Neurosci Lett ; 440(1): 81-6, 2008 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-18547725

RESUMO

The pathogenesis of cerebral vasospasm after subarachnoid haemorrhage (SAH) involves sustained contraction of arterial smooth muscle cells that is maximal 6-8 days after SAH. We reported that function of voltage-gated K+ (KV) channels was significantly decreased during vasospasm 7 days after SAH in dogs. Since arterial constriction is regulated by membrane potential that in turn is determined predominately by K+ conductance, the compromised K+ channel dysfunction may cause vasospasm. Additional support for this hypothesis would be demonstration that K+ channel dysfunction is temporally coincident with vasospasm. To test this hypothesis, SAH was created using the double haemorrhage model in dogs and smooth muscle cells from the basilar artery, which develops vasospasm, were isolated 4 days (early vasospasm), 7 days (during vasospasm) and 21 days (after vasospasm) after SAH and studied using patch-clamp electrophysiology. We investigated the two main K+ channels (KV and large-conductance voltage/Ca2+-activated (KCa) channels). Electrophysiologic function of KCa channels was preserved at all times after SAH. In contrast, function of KV channels was significantly decreased at all times after SAH. The decrease in cell size and degree of KV channel dysfunction was maximal 7 days after SAH. The results suggest that KV channel dysfunction either only partially contributes to vasospasm after SAH or that compensatory mechanisms develop that lead to resolution of vasospasm before KV channels recover their function.


Assuntos
Artéria Basilar/patologia , Músculo Liso Vascular/patologia , Músculo Liso Vascular/fisiopatologia , Canais de Potássio/fisiologia , Hemorragia Subaracnóidea/patologia , Animais , Células Cultivadas , Angiografia Cerebral/métodos , Modelos Animais de Doenças , Cães , Relação Dose-Resposta à Radiação , Condutividade Elétrica , Estimulação Elétrica/métodos , Potenciais da Membrana/fisiologia , Potenciais da Membrana/efeitos da radiação , Técnicas de Patch-Clamp/métodos , Distribuição Aleatória , Fatores de Tempo , Vasoespasmo Intracraniano/etiologia , Vasoespasmo Intracraniano/patologia
17.
J Vasc Res ; 45(5): 402-15, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18401179

RESUMO

Cerebral vasospasm after subarachnoid hemorrhage (SAH) is due to contraction of smooth muscle cells in the cerebral arteries. The mechanism of this contraction, however, is not well understood. Smooth muscle contraction is regulated in part by membrane potential, which is determined by K+ conductance in smooth muscle. Voltage-gated (Kv) and large-conductance, Ca2+-activated K+ (BK) channels dominate arterial smooth muscle K+ conductance. Vasospastic smooth muscle cells are depolarized relative to normal cells, but whether this is due to altered Kv or BK channel function has not been determined. This study determined if BK channels are altered during vasospasm after SAH in dogs. We first characterized BK channels in basilar-artery smooth muscle using whole-cell patch clamping and single-channel recordings. Next, we compared BK channel function between normal and vasospastic cells. There were no significant differences between normal and vasospastic cells in BK current density, kinetics, Ca2+ and voltage sensitivity, single-channel conductance or apparent Ca2+ affinity. Basilar-artery myocytes had no, small- or intermediate-conductance, Ca2+-activated K+ channels. The lack of difference in BK channels between vasospastic and control cells suggests alteration(s) in other K+ channels or other ionic conductances may underlie the membrane depolarization and vasoconstriction observed during vasospasm after SAH.


Assuntos
Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Potássio/metabolismo , Hemorragia Subaracnóidea/complicações , Vasoconstrição , Vasoespasmo Intracraniano/metabolismo , Animais , Artéria Basilar/metabolismo , Artéria Basilar/fisiopatologia , Cálcio/metabolismo , Angiografia Cerebral , Modelos Animais de Doenças , Cães , Cinética , Modelos Cardiovasculares , Músculo Liso Vascular/fisiopatologia , Técnicas de Patch-Clamp , Hemorragia Subaracnóidea/metabolismo , Hemorragia Subaracnóidea/fisiopatologia , Vasoespasmo Intracraniano/etiologia , Vasoespasmo Intracraniano/fisiopatologia
18.
Neurosurg Focus ; 21(3): E8, 2006 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-17029347

RESUMO

Cerebral vasospasm and delayed cerebral ischemia remain common complications of aneurysmal subarachnoid hemorrhage (SAH), and yet therapies for cerebral vasospasm are limited. Despite a large number of clinical trials, only calcium antagonists have strong evidence supporting their effectiveness. The purpose of this work was to perform a systematic review of the literature on the treatment of cerebral vasospasm. A literature search for randomized controlled trials of therapies used for prevention or treatment of cerebral vasospasm and/or delayed cerebral ischemia was conducted, and 41 articles meeting the review criteria were found. Study characteristics and primary results of these articles are reviewed. Key indicators of quality were poor when averaged across all studies, but have improved greatly over time. The only proven therapy for vasospasm is nimodipine. Tirilazad is not effective, and studies of hemodynamic maneuvers, magnesium, statin medications, endothelin antagonists, steroid drugs, anticoagulant/antiplatelet agents, and intrathecal fibrinolytic drugs have yielded inconclusive results. The following conclusions were made: nimodipine is indicated after SAH and tirilazad is not effective. More study of hemodynamic maneuvers, the effectiveness of other calcium channel antagonists such as nicardipine delivered by other routes (for example intrathecally), magnesium, statin drugs, endothelin antagonists, and intrathecal fibrinolytic therapy is warranted. There is less enthusiasm for the study of steroid drugs and anticoagulant/antiplatelet agents because they entail more risks and investigations so far have shown little evidence of efficacy. The study of rescue therapy such as balloon angioplasty and intraarterial vasodilating agents will be difficult. The quality of clinical trials should be improved.


Assuntos
Medicina Baseada em Evidências , Hemorragia Subaracnóidea/terapia , Vasoespasmo Intracraniano/terapia , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , MEDLINE/estatística & dados numéricos , Magnésio/uso terapêutico , Peptídeos Cíclicos/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Literatura de Revisão como Assunto
19.
J Cereb Blood Flow Metab ; 26(3): 382-91, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16079788

RESUMO

Cerebral vasospasm after subarachnoid hemorrhage (SAH) is because of smooth muscle contraction, although the mechanism of this contraction remains unresolved. Membrane potential controls the contractile state of arterial myocytes by gating voltage-sensitive calcium channels and is in turn primarily controlled by K(+) ion conductance through several classes of K(+) channels. We characterized the role of inwardly rectifying K(+) (K(IR)) channels in vasospasm. Vasospasm was created in dogs using the double-hemorrhage model of SAH. Electrophysiological, real-time quantitative reverse-transcriptase polymerase chain reaction, Western blotting, immunohistochemistry, and isometric tension techniques were used to characterize the expression and function of K(IR) channels in normal and vasospastic basilar artery 7 days after SAH. Subarachnoid hemorrhage resulted in severe vasospasm of the basilar artery (mean of 61% +/- 5% reduction in diameter). Membrane potential of pressurized vasospastic basilar arteries was significantly depolarized compared with control arteries (-46 +/- 1.4 mV versus -29.8 +/- 1.8 mV, respectively, P < 0.01). In whole-cell patch clamp of enzymatically isolated basilar artery myocytes, average K(IR) conductance was 1.6 +/- 0.5 pS/pF in control cells and 9.2 +/- 2.2 pS/pF in SAH cells (P = 0.007). Blocking K(IR) channels with BaCl(2) (0.1 mmol/L) resulted in significantly greater membrane depolarization in vasospastic compared with normal myocytes. Expression of K(IR) 2.1 messenger ribonucleic acid (mRNA) was increased after SAH. Western blotting and immunohistochemistry also showed increased expression of K(IR) protein in vasospastic smooth muscle. Blockage of K(IR) channels in arteries under isometric tension produced a greater contraction in SAH than in control arteries. These results document increased expression of K(IR) 2.1 mRNA and protein during vasospasm after experimental SAH and suggest that this increase is a functionally significant adaptive response acting to reduce vasospasm.


Assuntos
Canais de Potássio Corretores do Fluxo de Internalização/genética , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Hemorragia Subaracnóidea/fisiopatologia , Vasoespasmo Intracraniano/fisiopatologia , Animais , Bário/farmacologia , Artéria Basilar/efeitos dos fármacos , Artéria Basilar/fisiopatologia , Pressão Sanguínea , Angiografia Cerebral , Modelos Animais de Doenças , Cães , Feminino , Potenciais da Membrana , Músculo Liso/metabolismo , Músculo Liso/fisiopatologia , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Potássio/metabolismo , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Hemorragia Subaracnóidea/complicações , Fatores de Tempo , Vasoespasmo Intracraniano/diagnóstico por imagem , Vasoespasmo Intracraniano/etiologia
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