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1.
Med Eng Phys ; 36(5): 607-12, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24508528

RESUMO

Cerebral autoregulation (CA) mechanisms maintain blood flow approximately stable despite changes in arterial blood pressure. Mathematical models that characterise this system have been used extensively in the quantitative assessment of function/impairment of CA. Using spontaneous fluctuations in arterial blood pressure (ABP) as input and cerebral blood flow velocity (CBFV) as output, the autoregulatory mechanism can be modelled using linear and non-linear approaches, from which indexes can be extracted to provide an overall assessment of CA. Previous studies have considered a single--or at most a couple of measures, making it difficult to compare the performance of different CA parameters. We compare the performance of established autoregulatory parameters and propose novel measures. The key objective is to identify which model and index can best distinguish between normal and impaired CA. To this end 26 recordings of ABP and CBFV from normocapnia and hypercapnia (which temporarily impairs CA) in 13 healthy adults were analysed. In the absence of a 'gold' standard for the study of dynamic CA, lower inter- and intra-subject variability of the parameters in relation to the difference between normo- and hypercapnia were considered as criteria for identifying improved measures of CA. Significantly improved performance compared to some conventional approaches was achieved, with the simplest method emerging as probably the most promising for future studies.


Assuntos
Encéfalo/fisiopatologia , Circulação Cerebrovascular , Homeostase , Modelos Biológicos , Adulto , Pressão Sanguínea , Humanos , Hipercapnia/fisiopatologia , Modelos Lineares , Dinâmica não Linear
2.
J Int Neuropsychol Soc ; 18(1): 79-88, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22114912

RESUMO

Three types of HIV-associated neurocognitive disorders (HAND) exist that are distinguished by presence and severity of impairment in cognitive and everyday functioning. Although well-validated neurocognitive measures exist, determining impairment in everyday functioning remains a challenge. We aim to determine whether Self-Report measures of everyday functioning are as effective in characterizing HAND as Performance-Based measures. We assessed 674 HIV-infected participants with a comprehensive neurocognitive battery; 233 met criteria for a HAND diagnosis by having at least mild neurocognitive impairment. Functional decline was measured via Self-Report and Performance-Based measures. HAND diagnoses were determined according to published criteria using three approaches to assess functional decline: (1) Self-Report measures only, (2) Performance-Based measures only, and (3) Dual-method combining Self-Report and Performance-Based measures. The Dual-method classified the most symptomatic HAND, compared to either singular method. Singular method classifications were 76% concordant with each other. Participants classified as Performance-Based functionally impaired were more likely to be unemployed and more immunosuppressed, whereas those classified as Self-Report functionally impaired had more depressive symptoms. Multimodal methods of assessing everyday functioning facilitate detection of symptomatic HAND. Singular Performance-Based classifications were associated with objective functional and disease-related factors; reliance on Self-Report classifications may be biased by depressive symptoms.


Assuntos
Atividades Cotidianas , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/etiologia , Infecções por HIV/complicações , Atividade Motora/fisiologia , Autorrelato , Adulto , Idoso , Transtornos Cognitivos/virologia , Estudos de Coortes , Depressão/etiologia , Feminino , Infecções por HIV/diagnóstico , Proteína HN/metabolismo , Humanos , Técnicas Imunoenzimáticas , Receptores de Lipopolissacarídeos/metabolismo , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Escalas de Graduação Psiquiátrica , Sensibilidade e Especificidade , Estatísticas não Paramétricas , Adulto Jovem
3.
J Public Health Dent ; 71 Suppl 1: S84-94, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21656962

RESUMO

The present paper addresses basic evaluation and procedural concepts that are involved in the process of implementing sustainable oral health behavioral and social interventions. It is part of a series of thematic articles describing cutting-edge methods for conducting oral health interventions research. Core components for effective intervention implementation are presented as part of a comprehensive model composed of four stages (training, adoption, implementation, and practice), along with sustaining influences involving preparation and maintenance. This model systematically addresses common barriers that can reduce innovation success and permanence. Special attention is given to the measurement and impact of organizational and related contextual influences across stages of the implementation process. Assessment tools and research strategies are recommended and illustrated based on evaluations of interventions implemented in addiction and mental health treatment systems. These tools and research strategies also hold promise for use within the National Institute of Dental and Craniofacial Research Practice-Based Research Networks, as well as other systems of oral health care delivery.


Assuntos
Terapia Comportamental/métodos , Comportamentos Relacionados com a Saúde , Implementação de Plano de Saúde/métodos , Promoção da Saúde , Modelos Teóricos , Saúde Bucal , Inovação Organizacional , Pesquisa Comportamental/métodos , Pesquisa Participativa Baseada na Comunidade/economia , Pesquisa Participativa Baseada na Comunidade/organização & administração , Difusão de Inovações , Odontologia Baseada em Evidências , Implementação de Plano de Saúde/economia , Promoção da Saúde/economia , Promoção da Saúde/métodos , Humanos , Avaliação de Processos e Resultados em Cuidados de Saúde/métodos , Avaliação de Programas e Projetos de Saúde , Projetos de Pesquisa , Estados Unidos
4.
Addiction ; 106(10): 1733-40, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20840168

RESUMO

For more than 40 years the Texas Institute of Behavioral Research (IBR) has given special attention to assessment and evaluation of drug user populations, addiction treatment services and various cognitive and behavioral interventions. Emphasis has been on studies in real-world settings and the use of multivariate methodologies to address evaluation issues within the context of longitudinal natural designs. Historically, its program of addiction treatment research may be divided into three sequential epochs-the first era dealt mainly with client assessment and its role in treatment outcome and evaluation (1969-89), the second focused upon modeling the treatment process and the importance of conceptual frameworks (1989-2009) in explaining the relationships among treatment environment, client attributes, treatment process and outcome, and the third (and current) era has expanded into studying tactical deployment of innovations and implementation. Recent projects focus upon adapting and implementing innovations for improving early engagement in adolescent residential treatment settings and drug-dependent criminal justice populations. Related issues include the spread of human immunodeficiency virus/acquired immune deficiency syndrome and other infectious diseases, organizational and systems functioning, treatment costs and process related to implementation of evidence-based practices.


Assuntos
Academias e Institutos/organização & administração , Comportamento Aditivo/terapia , Pesquisa Comportamental/organização & administração , Transtornos Relacionados ao Uso de Substâncias/terapia , Adolescente , Comportamento Aditivo/economia , Comportamento Aditivo/psicologia , Pesquisa Comportamental/economia , Pesquisa Comportamental/tendências , Aconselhamento/métodos , Prática Clínica Baseada em Evidências , Infecções por HIV/prevenção & controle , Custos de Cuidados de Saúde , Humanos , Cooperação Internacional , Cultura Organizacional , Objetivos Organizacionais , Relações Profissional-Paciente , Apoio à Pesquisa como Assunto , Tratamento Domiciliar , Transtornos Relacionados ao Uso de Substâncias/economia , Transtornos Relacionados ao Uso de Substâncias/psicologia , Texas , Resultado do Tratamento , Reino Unido , Universidades
8.
Neurology ; 70(19): 1691-8, 2008 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-18458229

RESUMO

OBJECTIVE: To perform an evidence-based review of the safety and efficacy of botulinum neurotoxin (BoNT) in the treatment of adult and childhood spasticity. METHODS: A literature search was performed including MEDLINE and Current Contents for therapeutic articles relevant to BoNT and spasticity. Authors reviewed, abstracted, and classified articles based on American Academy of Neurology criteria (Class I-IV). RESULTS: The highest quality literature available for the respective indications was as follows: adult spasticity (14 Class I studies); spastic equinus and adductor spasticity in pediatric cerebral palsy (six Class I studies). RECOMMENDATIONS: Botulinum neurotoxin should be offered as a treatment option for the treatment of spasticity in adults and children (Level A).


Assuntos
Toxinas Botulínicas/administração & dosagem , Espasticidade Muscular/tratamento farmacológico , Músculo Esquelético/efeitos dos fármacos , Bloqueadores Neuromusculares/administração & dosagem , Adulto , Fatores Etários , Criança , Ensaios Clínicos como Assunto/estatística & dados numéricos , Relação Dose-Resposta a Droga , Medicina Baseada em Evidências/métodos , Humanos , Espasticidade Muscular/etiologia , Espasticidade Muscular/fisiopatologia , Músculo Esquelético/inervação , Músculo Esquelético/fisiopatologia , Resultado do Tratamento
9.
Neurology ; 70(19): 1699-706, 2008 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-18458230

RESUMO

OBJECTIVE: To perform an evidence-based review of the safety and efficacy of botulinum neurotoxin (BoNT) in the treatment of movement disorders. METHODS: A literature search was performed including MEDLINE and Current Contents for therapeutic articles relevant to BoNT and selected movement disorders. Authors reviewed, abstracted, and classified articles based on American Academy of Neurology criteria (Class I-IV). RESULTS: The highest quality literature available for the respective indications was as follows: blepharospasm (two Class II studies); hemifacial spasm (one Class II and one Class III study); cervical dystonia (seven Class I studies); focal upper extremity dystonia (one Class I and three Class II studies); focal lower extremity dystonia (one Class II study); laryngeal dystonia (one Class I study); motor tics (one Class II study); and upper extremity essential tremor (two Class II studies). RECOMMENDATIONS: Botulinum neurotoxin should be offered as a treatment option for the treatment of cervical dystonia (Level A), may be offered for blepharospasm, focal upper extremity dystonia, adductor laryngeal dystonia, and upper extremity essential tremor (Level B), and may be considered for hemifacial spasm, focal lower limb dystonia, and motor tics (Level C). While clinicians' practice may suggest stronger recommendations in some of these indications, evidence-based conclusions are limited by the availability of data.


Assuntos
Toxinas Botulínicas/administração & dosagem , Distúrbios Distônicos/tratamento farmacológico , Transtornos dos Movimentos/tratamento farmacológico , Bloqueadores Neuromusculares/administração & dosagem , Ensaios Clínicos como Assunto/estatística & dados numéricos , Distúrbios Distônicos/classificação , Distúrbios Distônicos/fisiopatologia , Tremor Essencial/tratamento farmacológico , Tremor Essencial/fisiopatologia , Medicina Baseada em Evidências , Humanos , Transtornos dos Movimentos/classificação , Transtornos dos Movimentos/fisiopatologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/inervação , Músculo Esquelético/fisiopatologia , Resultado do Tratamento
10.
Neurology ; 70(19): 1707-14, 2008 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-18458231

RESUMO

OBJECTIVE: To perform an evidence-based review of the safety and efficacy of botulinum neurotoxin (BoNT) in the treatment of autonomic and urologic disorders and low back and head pain. METHODS: A literature search was performed including MEDLINE and Current Contents for therapeutic articles relevant to BoNT and the selected indications. Authors reviewed, abstracted, and classified articles based on the quality of the study (Class I-IV). Conclusions and recommendations were developed based on the highest level of evidence and put into current clinical context. RESULTS: The highest quality literature available for the respective indications was as follows: axillary hyperhidrosis (two Class I studies); palmar hyperhidrosis (two Class II studies); drooling (four Class II studies); gustatory sweating (five Class III studies); neurogenic detrusor overactivity (two Class I studies); sphincter detrusor dyssynergia in spinal cord injury (two Class II studies); chronic low back pain (one Class II study); episodic migraine (two Class I and two Class II studies); chronic daily headache (four Class II studies); and chronic tension-type headache (two Class I studies). RECOMMENDATIONS: Botulinum neurotoxin (BoNT) should be offered as a treatment option for the treatment of axillary hyperhidrosis and detrusor overactivity (Level A), should be considered for palmar hyperhidrosis, drooling, and detrusor sphincter dyssynergia after spinal cord injury (Level B), and may be considered for gustatory sweating and low back pain (Level C). BoNT is probably ineffective in episodic migraine and chronic tension-type headache (Level B). There is presently no consistent or strong evidence to permit drawing conclusions on the efficacy of BoNT in chronic daily headache (mainly transformed migraine) (Level U). While clinicians' practice may suggest stronger recommendations in some of these indications, evidence-based conclusions are limited by the availability of data.


Assuntos
Doenças do Sistema Nervoso Autônomo/tratamento farmacológico , Toxinas Botulínicas/administração & dosagem , Bloqueadores Neuromusculares/administração & dosagem , Dor/tratamento farmacológico , Doenças do Sistema Nervoso Autônomo/fisiopatologia , Ensaios Clínicos como Assunto/estatística & dados numéricos , Medicina Baseada em Evidências , Humanos , Hiperidrose/tratamento farmacológico , Dor Lombar/tratamento farmacológico , Dor/fisiopatologia , Bexiga Urinaria Neurogênica/tratamento farmacológico
11.
Sci Pract Perspect ; 3(2): 20-8, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17514069

RESUMO

Innovate and adapt are watchwords for substance abuse treatment programs in today's environment of legislative mandates, effective new interventions, and competition. Organizations are having to evolve - ready or not - and those that are ready have superior chances for success and survival. The Texas Christian University Organizational Readiness for Change (ORC) survey is a free instrument, with supporting materials, that substance abuse treatment programs use to assess organizational traits that can facilitate or hinder efforts at transition. This article presents organizational change as a three-stage process of adopting, implementing, and routinizing new procedures; describes the use of the ORC; and outlines a step-by-step procedure for clearing away potential obstacles before setting forth on the road to improved practices and outcomes.


Assuntos
Auditoria Administrativa/métodos , Avaliação de Programas e Projetos de Saúde/métodos , Centros de Tratamento de Abuso de Substâncias/organização & administração , Inquéritos e Questionários , Humanos , Inovação Organizacional , Objetivos Organizacionais , Avaliação de Resultados em Cuidados de Saúde/métodos , Reprodutibilidade dos Testes , Transtornos Relacionados ao Uso de Substâncias/terapia
12.
J Subst Abuse Treat ; 33(2): 131-7, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17433861

RESUMO

Organizational functioning within substance abuse treatment organizations is important to the transfer of research innovations into practice. Programs should be performing well for new interventions to be implemented successfully. This study examined the characteristics of treatment programs that participated in an assessment and training workshop designed to improve organizational functioning. The workshop was attended by directors and clinical supervisors from 53 community-based treatment units in a single state in the Southwest. Logistic regression analysis was used to examine attributes related to program-level decisions to engage in a structured process for making organizational changes. Findings showed that programs with higher needs and pressures, more limited institutional resources, and poorer ratings on staff attributes and organizational climate were the most likely to engage in a change strategy. Furthermore, organizations with greater staff consensus (i.e., smaller standard deviations) on ratings of organizational climate were also more likely to engage in change.


Assuntos
Inovação Organizacional , Avaliação de Programas e Projetos de Saúde , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Transtornos Relacionados ao Uso de Substâncias/terapia , Assistência Ambulatorial , Educação Continuada , Humanos , Serviços de Saúde Mental , Avaliação de Processos e Resultados em Cuidados de Saúde , Transferência de Tecnologia
13.
J Subst Abuse Treat ; 33(2): 139-47, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17433863

RESUMO

This study focused on the relationship between organizational functioning factors measured in a staff survey using the Texas Christian University (TCU) Organizational Readiness for Change assessment and client-level engagement measured by the TCU Client Evaluation of Self and Treatment in drug treatment programs. The sample consisted of 531 clinical and counseling staff and 3,475 clients from 163 substance abuse treatment programs located in nine states from three regional Addiction Technology Transfer Centers. Measures of client engagement in treatment (rapport, satisfaction, and participation) were shown to be higher in programs with more positive staff ratings of organizational functioning. In particular, these programs had fewer agency needs and more favorable ratings for their resources, staff attributes, and climate. These findings help establish the importance of addressing organizational factors as part of an overall strategy for improving treatment effectiveness.


Assuntos
Participação do Paciente/psicologia , Centros de Tratamento de Abuso de Substâncias/organização & administração , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Serviços Comunitários de Saúde Mental/organização & administração , Aconselhamento , Necessidades e Demandas de Serviços de Saúde , Humanos , Serviços de Saúde Mental , Relações Profissional-Paciente , Transtornos Relacionados ao Uso de Substâncias/psicologia , Transferência de Tecnologia , Resultado do Tratamento
14.
J Subst Abuse Treat ; 33(2): 121-9, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17434705

RESUMO

Assessments of treatment staff training needs, preferences, and barriers can help guide and improve training activities and transfer evidence-based technologies into clinical practice. The Texas Christian University (TCU) Program Training Needs (PTN) assessment consists of 54 items organized into seven domains: Program Facilities and Climate, Program Computer Resources, Staff Training Needs, Preferences for Training Content, Preferences for Training Strategy, Training Barriers, and Satisfaction With Training. Data collected from 589 counselors representing 194 treatment programs showed that the PTN was psychometrically sound and predictably associated with results from a more comprehensive assessment of organizational functioning. Importantly, fewer barriers to training and greater staff satisfaction with training were reported for programs with higher levels of organizational functioning. In addition to representing an efficient source of staff's perceptions about organizational operations and needs, the PTN empowers staff with a "voice" through which they can contribute to strategic planning and priority setting for organizational actions.


Assuntos
Necessidades e Demandas de Serviços de Saúde , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Transtornos Relacionados ao Uso de Substâncias/terapia , Aconselhamento , Currículo , Planejamento em Saúde , Humanos , Capacitação em Serviço , Avaliação das Necessidades , Planejamento de Assistência ao Paciente , Avaliação de Programas e Projetos de Saúde , Centros de Tratamento de Abuso de Substâncias
15.
J Subst Abuse Treat ; 33(2): 193-9, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17434707

RESUMO

The prevailing emphasis on adopting evidence-based practices suggests that more focused training evaluations that capture factors in clinician decisions to use new techniques are needed. This includes relationships between postconference evaluations and subsequent adoption of training materials. We therefore collected training assessments at two time points from substance abuse treatment counselors who attended a training on dual diagnosis and another on therapeutic alliance as part of a state-sponsored conference. Customized evaluations were collected to assess counselor perceptions of training quality, relevance, and resources in relation to its use during the 6 months after the conference. Higher ratings for relevance of training concepts and materials to service the needs of clients, desire to have additional training, and level of program support were related to greater trial use during the follow-up period. Primary resource-related and procedural barriers cited by the counselors included lack of time and redundancy with existing practices.


Assuntos
Aconselhamento , Transtornos Relacionados ao Uso de Substâncias/terapia , Serviços Comunitários de Saúde Mental , Medicina Baseada em Evidências , Necessidades e Demandas de Serviços de Saúde , Pesquisa sobre Serviços de Saúde , Humanos , Percepção , Avaliação de Programas e Projetos de Saúde , Alocação de Recursos , Centros de Tratamento de Abuso de Substâncias , Transtornos Relacionados ao Uso de Substâncias/reabilitação
16.
J Subst Abuse Treat ; 33(2): 149-58, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17434709

RESUMO

A key goal of drug abuse treatment providers is getting their clients to engage and participate in therapeutic activities as a first step toward deriving longer-term benefits. Much research had focused on personal characteristics that relate to client engagement; program characteristics have received less attention. This study explored client and program differences in engagement ratings using data from a nationwide set of 94 outpatient drug-free treatment programs in a hierarchical linear model analysis. The results show that elements of program context, including structural features (e.g., smaller size and Joint Commission on the Accreditation of Healthcare Organizations/Commission on Accreditation of Rehabilitation Facilities accreditation) and staff's perceptions of personal efficacy, organizational climate, and communal workplace practices, relate to better overall client engagement. These findings add further evidence that treatment providers should also address the workplace environment for staff as part of quality improvement efforts.


Assuntos
Motivação , Relações Profissional-Paciente , Meio Social , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Transtornos Relacionados ao Uso de Substâncias/terapia , Efeitos Psicossociais da Doença , Humanos , Joint Commission on Accreditation of Healthcare Organizations , Admissão e Escalonamento de Pessoal , Centros de Tratamento de Abuso de Substâncias , Transtornos Relacionados ao Uso de Substâncias/economia , Estados Unidos
17.
Eur Addict Res ; 12(4): 176-81, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16968992

RESUMO

To better understand why some drug abuse treatment programs are more effective than others, USA research about organizational functioning and its role in the provision of treatment services was extended through a study of a delivery system in another country. The Texas Christian University (TCU) organizational functioning and readiness for change instrument (ORC) was translated into Italian and administered to 405 treatment program directors and staff from both public and private sectors in the Veneto Region of Northern Italy. Results indicated that the psychometric properties of the ORC in the USA and Italy are consistent. Some general differences in staff attributes were found between USA and Italian programs, but organizational climates were remarkably similar.


Assuntos
Auditoria Administrativa/métodos , Serviços de Saúde Mental/organização & administração , Cultura Organizacional , Inovação Organizacional , Avaliação de Resultados em Cuidados de Saúde/organização & administração , Psicometria/instrumentação , Centros de Tratamento de Abuso de Substâncias/organização & administração , Inquéritos e Questionários , Adulto , Atitude , Feminino , Humanos , Cooperação Internacional , Itália , Masculino , Pessoa de Meia-Idade , Transtornos Relacionados ao Uso de Substâncias/etnologia , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Texas , Estados Unidos
18.
Neurology ; 66(11): 1679-87, 2006 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-16769940

RESUMO

BACKGROUND: Distal sensory polyneuropathy (DSP) is the most common neurologic complication of human immunodeficiency virus (HIV) infection. Risk factors for DSP have not been adequately defined in the era of highly active antiretroviral therapy. METHODS: The authors evaluated 101 subjects with advanced HIV infection over 48 weeks. Assessments included a brief peripheral neuropathy (PN) screen (BPNS), neurologic examination, nerve conduction studies, quantitative sensory testing (QST), and skin biopsies with quantitation of epidermal nerve fiber density. Data were summed into a Total Neuropathy Score (TNS). The presence, severity, and progression of DSP were related to clinical and laboratory results. RESULTS: The mean TNS (range 0 to 36) was 8.9, with 38% of subjects classified as PN-free, 10% classified as having asymptomatic DSP, and 52% classified as having symptomatic DSP. Progression in TNS from baseline to week 48 occurred only in the PN-free group at baseline (mean TNS change = 1.16 +/- 2.76, p = 0.03). Factors associated with progression in TNS were lower current TNS, distal epidermal denervation, and white race. As compared with the TNS diagnosis of PN at baseline, the BPNS had a sensitivity of 34.9% and a specificity of 89.5%. CONCLUSIONS: In this cohort of advanced human immunodeficiency virus (HIV)-infected subjects, distal sensory polyneuropathy was common and relatively stable over 48 weeks. Previously established risk factors, including CD4 cell count, plasma HIV RNA, and use of dideoxynucleoside antiretrovirals were not predictive of the progression of distal sensory polyneuropathy (DSP). Distal epidermal denervation was associated with worsening of DSP. As compared with the Total Neuropathy Score, the brief peripheral neuropathy screen had relatively low sensitivity and high specificity for the diagnosis of DSP.


Assuntos
Infecções por HIV/diagnóstico , Infecções por HIV/epidemiologia , Polineuropatias/diagnóstico , Polineuropatias/epidemiologia , Medição de Risco/métodos , Transtornos de Sensação/diagnóstico , Transtornos de Sensação/epidemiologia , Estudos de Coortes , Comorbidade , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde/métodos , Fatores de Risco , Índice de Gravidade de Doença , Estados Unidos/epidemiologia
19.
Physiol Meas ; 27(1): 35-49, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16365509

RESUMO

A number of different system identification techniques have been proposed to assess dynamic cerebral autoregulation in critically ill patients. From these methods, the response to a standard stepwise change in blood pressure can be estimated. Responses lacking physiological consistency are a common occurrence and could be the consequence of particular system identification procedures or, alternatively, caused by measurements with a poor signal-to-noise ratio. A multi-observer approach was adopted in this paper to classify cerebral blood flow velocity (CBFV) step responses to spontaneous changes in arterial blood pressure in a group of 43 neonates with a mean gestational age of 33.7 weeks (range 24-42 weeks) and a mean birthweight of 1,980 g (range 570-3,910 g). Three experienced observers independently analysed the estimated step responses in 191 recordings each lasting 100 s; for an autoregressive (ARX) model, 124 (65%) of the step responses were accepted by at least two of the three observers. Two other system identification methods, transfer function analysis and the moving average Wiener-Laguerre model, gave 90 (45%) and 98 (51%) acceptable responses, respectively. Only 54 epochs (28%) were accepted with all three methods. With 88 (46%) responses rejected by at least two methods, it can be concluded that signal quality was the main reason for nonphysiological step responses. To avoid the need for subjective visual selection, an automatic procedure for classifying step responses was implemented leading to sensitivities and specificities in the range 85-90%, with respect to the agreement with subjective evaluations. Objective selection of CBFV step responses is thus feasible and could also be adapted for other physiological measurement techniques relying on system identification methods.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Homeostase , Humanos , Recém-Nascido , Análise de Regressão , Processamento de Sinais Assistido por Computador/instrumentação
20.
Physiol Meas ; 26(5): 725-41, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16088064

RESUMO

Cerebral autoregulation maintains a relatively constant blood flow despite changes of blood pressure in the brain. Linear models have been extensively applied to identify this mechanism, using spontaneous arterial blood pressure (ABP) fluctuation as input and cerebral blood flow velocity (CBFV) change as output. Although valuable measurements have been achieved by these models, accuracy and consistency are of great concern due to the large variability of results. We therefore investigated whether more reliable measurements can be achieved by selecting only those recordings (or parts of recordings) with relatively high spontaneous variability of ABP. Twenty-four recordings, 7 from hypercapnia and 17 from normocapnia, of ABP and CBFV from 9 healthy adults were analyzed. Two conventional autoregulatory parameters were used to assess cerebral autoregulation. In the absence of a 'gold' standard for the study of dynamic cerebral autoregulation, lower variability of the parameters and higher correlation with pCO(2) were considered as criteria for identifying improved measures of autoregulation. Both significantly lower variability of the parameters, and higher correlation between the parameters and pCO(2) were achieved from the data with higher variability of blood pressure. We therefore conclude that ABP with high variability may effectively stimulate regulatory response in blood flow resulting in improved assessment of cerebral autoregulation.


Assuntos
Artérias/fisiologia , Pressão Sanguínea , Circulação Cerebrovascular , Velocidade do Fluxo Sanguíneo , Homeostase , Humanos
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