Effects of neuromuscular electrical stimulation on exercise capacity, muscle strength and quality of life in COPD patients: A Systematic Review with Meta-Analysis.

OBJECTIVE: To determine the effects of neuromuscular electrical stimulation on disabilities and activity limitation of individuals affected by chronic obstructive pulmonary disease. DATA SOURCES: MEDLINE, PEDro database, Cochrane Controlled Trials Register, and SciELO, were searched from inception until October 2021. REVIEW METHODS: Inclusion criteria were patients with COPD, randomized controlled trials comparing neuromuscular electrical stimulation alone or combined conventional pulmonary rehabilitation and neuromuscular electrical stimulation versus control or sham or pulmonary rehabilitation in disabilities and activity limitation in COPD. There were no mandatory language or publication date restrictions. Two reviewers selected studies independently. Weighted mean differences and 95% confidence intervals were calculated. Results 32 studies met the study criteria, including 1.269 participants. Neuromuscular electrical stimulation improved exercise capacity (MD 1.10, 95% CI: 0.33, 1.86, N = 147), and muscle strength (0.53, 95% CI: 0.20, 0.87, N = 147) compared to sham group. Combined neuromuscular electrical stimulation and conventional rehabilitation improved exercise capacity (MD 34.28 meters, 95% CI: 6.84, 61.73, N = 262) compared to conventional rehabilitation alone. No adverse events were reported. CONCLUSIONS: Neuromuscular electrical stimulation resulted in small improvement in disabilities and activity limitation (below the MCID) in COPD. Thus, the inclusion of neuromuscular electrical stimulation in rehabilitation programs must consider the cost Because of inadequate methodological conduction and reporting of methods, some studies were of low quality.

Effect of Aerobic Exercise on Peak Oxygen Consumption, VE/VCO2 Slope, and Health-Related Quality of Life in Patients with Heart Failure with Preserved Left Ventricular Ejection Fraction: a Systematic Review and Meta-Analysis.

PURPOSE OF REVIEW: The aim of this study was to determine the effects of aerobic exercise on peak oxygen uptake (peak VO2), minute ventilation/carbon dioxide production (VE/VCO2 slope), and health-related quality of life (HRQoL) among patients with heart failure (HF) and preserved ejection fraction (HFpEF). RECENT FINDINGS: We conducted a Cochrane Library, MEDLINE/PubMed, Physiotherapy Evidence Database, and SciELO search (from 1985 to May 2019) for randomized controlled trials that evaluated the effects of aerobic exercise in HFpEF patients. We calculated the mean differences (MD) and 95% confidence interval (CI). Ten intervention studies were included providing a total of 399 patients. Compared with control, aerobic exercise resulted in improvement in peak VO2 MD 1.9 mL kg-1 min-1 (95% CI 1.3 to 2.5; N = 314) and HRQoL measured by Minnesota Living with Heart Failure MD 5.4 (95% CI - 10.5 to - 0.2; N = 256). No significant difference in VE/VCO2 slope was found between participants in the aerobic exercise group and the control group. The quality of evidence for peak VO2 and HRQoL was assessed as being moderate. Aerobic exercise moderately improves peak VO2 and HRQoL and should be considered a strategy of rehabilitation of HFpEF individuals.

Effects of isokinetic muscle strengthening on muscle strength, mobility, and gait in post-stroke patients: a systematic review and meta-analysis.

OBJECTIVE:: To investigate whether isokinetic muscle strengthening improves muscle strength, mobility, and gait in post-stroke patients. METHODS:: We searched for randomized controlled trials at PubMed/Medline, SciELO, PEDro, and Cochrane Central Register of Controlled Trials, from the earliest date available to June 2018. Randomized controlled trials that examined the effects of isokinetic muscle strengthening versus other rehabilitation interventions or control in post-stroke patients were included. Study quality was evaluated using the PEDro scale. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed using the I2 test. RESULTS:: In total, 13 studies (347 patients) focusing on the use of isokinetic in rehabilitation following stroke were included. All trials were of low-to-moderate quality. Isokinetic muscle strengthening improved muscle strength WMD 0.8 (95% CI: 0.2, 1.4; N = 96), mobility WMD -2.03 seconds (95% CI: -2.9, -1.1; N = 111) and gait speed WMD 0.9 m/s (95% CI: 0.05, 1.8; N = 87). CONCLUSION:: Isokinetic muscle strengthening seems to be a useful strategy for improving muscle strength, mobility, and gait in post-stroke patients.

Development, reliability, and validity of the mobility assessment scale in hospitalized patients (HMob).

BACKGROUND: Existing mobility scales for hospitalized patients do not include assessment of tasks for the right and left side, ability to transfer from sitting to lying and from standing to sitting, ability to climbing steps and pick up an object from the floor in the same instrument. OBJECTIVE: Evaluate the reliability and validity of the hospital mobility assessment scale (HMob) according to the Consensus-based standards for the selection of health measurement instruments (COSMIN). METHODS: Study conducted in three inpatient units (cardiology, neurology, and gastrohepatology) and one adult intensive care unit in a hospital. Patients of both sexes were included; age >18 years; collaborative and who obeyed commands, with different medical diagnoses and clinical release to leave their bed (provided by the doctor). Special populations such as those with burns and orthopedics were excluded. RESULTS: The sample consisted of 130 patients; 20 from the pilot study and 110 to assess the clinimetric properties of the HMob. Cronbach alpha coefficient was 0.949. Relative intra- (A1-A2) and inter-rater (A1-B; A2-B) reliability was excellent (A1-A2: ICC = 0.982, p-value < 0.0001; A1-B: ICC = 0.993, p-value < 0.0001; A2-B: ICC = 0.986, p-value < 0.0001.) The convergent criterion validity of HMob in relation to the ICU Functional Status Score was 0.967 (p-value < 0.0001) and for Functional Independence measure (MIF) was 0.926 (p-value < 0.0001). CONCLUSION: The HMob scale showed excellent internal consistency, intra- and inter-rater reliability, and concurrent validity in the motor domain, which suggests that it can be used in daily practice to measure mobility in hospitalized patients.

Lung and physical function in post COVID-19 and clinical and functional associations: a cross-sectional study in Brazil.

OBJECTIVE: The purpose of this study was to assess exercise capacity, lung and physical function in COVID-19 survivors, and the association of lesion-level characteristics assessed by chest computed tomography, probable sarcopenia, and percentage of diffusing capacity of the lung for carbon monoxide with clinical and functional variables. METHODS: This study was conducted in Salvador, Bahia, Brazil. All patients had a laboratory-confirmed SARS-CoV-2 infection. The sociodemographic characteristics, COVID-19 exposure history, pulmonary function, computed tomography, and functionality of the participants between 1 and 3 months of diagnosis of the disease were collected. RESULTS: A total of 135 patients after COVID-19 recovery were included in this study. Probable sarcopenia, reduction in percentage of diffusing capacity of the lung for carbon monoxide, and a lower 6-min walk distance were observed after COVID-19 infection. Computed tomography>50% was associated with a longer length of stay and a lower percentage of diffusing capacity of the lung for carbon monoxide. Probable sarcopenia diagnosis was associated with a worse percentage of the predicted 6-min walk distance in relation to the predicted, absolute 6-min walk distance (m), percentage of diffusing capacity of the lung for carbon monoxide, and percentage of total lung capacity. CONCLUSION: Muscle disability and lung dysfunction are common in COVID-19 survivors. Hospitalization was associated with the worst muscle force and diffusing capacity of the lung for carbon monoxide. Computed tomography characteristics could be a marker of prolonged hospital stay after the acute phase of COVID-19. Additionally, the probable diagnosis of sarcopenia could be a marker of impact on walking distance. These results highlight the need for long-term follow-up of those patients and rehabilitation programs.

Effects of water-based exercises on functioning of postmenopausal women: A systematic review with meta-analysis.

OBJECTIVE: The aim of the present study was to compare the efficacy of Water-Based Exercise (WBE) versus Land-Based Exercise (LBE) and of WBE versus Non-Exercise in postmenopausal women on muscle strength, agility, flexibility, bone mineral density and aerobic capacity. METHODS: We systematically searched in MEDLINE, PEDro, SciELO and the Cochrane Library RCT published until May 2022. Only randomized controlled trials were included. We analyzed the pooled results using weighted mean differences, standardized mean difference, and 95%CI were calculated. RESULTS: Twenty studies met the inclusion criteria; although, sixteen studies were included in the meta-analyses. The studies presented low methodological quality. WBE was more effective than NE for improving muscle strength of knee extension (3.34), knee flexion (2.51), arm curl (6.78 repetitions), VO2Max (4.12 ml/kg), and flexibility (6.38 cm) When comparing WBE with LBE, no significant statistical difference was found regarding muscular strength of lower limbs (1.00), muscular strength of upper limbs (0.47), flexibility (1.95 cm), aerobic capacity (0.82 ml/kg) and lumbar bone mineral density (0.04 g/cm2). CONCLUSIONS: WBE promotes significant benefits in muscle strength, aerobic capacity, and flexibility, when compared to no intervention. However, WBE was similar to the LBE for improving muscle strength, aerobic capacity, flexibility, agility, and bone mineral density - lumbar in postmenopausal women.

Effects of ventilator hyperinflation on pulmonary function and secretion clearance in adults receiving mechanical ventilation: A systematic review with meta-analysis.

INTRODUCTION: It is important to clarify the effect of ventilator hyperinflation(VHI) on pulmonary function and secretion clearance in adults receiving mechanical ventilation(MV). There is no published meta-analysis on the effects VHI on pulmonary function and secretion clearance in adults receiving MV. Objective Analyze the published randomized clinical trials(RCTs) that investigated the effects of VHI on pulmonary function and secretion clearance in adults receiving MV, comparing VHI with isolated aspiration, VHI with manual hyperinflation(MHI), VHI +vibrocompression(VB) versus VB and VHI+VB versus isolated aspiration. METHODS: The following databases PubMed, LILACS, EMBASE, SciELO, PEDro database and Cochrane Central Register of Controlled Trials (CENTRAL) were consulted up to December 2021. Secretion clearance, static and dynamic compliance of the respiratory system(Cstat and Cdyn), airway resistance(Raw) and oxygenation outcomes were evaluated. RESULTS: Thirteen studies met the study criteria, but only 12 studies were included on meta-analysis. There was no difference between VHI versus isolated aspiration for amount of secretions removed(0.41 SMD; 95% CI: -0.08 to 0.89; n=270), VHI versus MHI(0.51 grams; 95% CI: -0.08 to 1.11; n=256), VHI+VB versus VB(0.31 grams; 95% CI: -0.42 to 1.05; n=130) and VHI+VB versus isolated aspiration(0.54 grams; 95% CI: -0.06 to 1.14; n=132). There was difference for VHI versus isolated aspiration to Cstat (4.77 ml/cm H2O; 95% CI: 2.41 to 7.14; n= 136). CONCLUSION: Taking into account all studies included in meta-analysis, no evidences was found that VHI was effective in increasing the amount of secretions removed, Cdyn and oxygenation, but VHI seems to show a slight improvement in Cstat when compared to isolated aspiration. No evidence was found that VHI was effective in increasing the amount of secretions removed, Cdyn and oxygenation, but VHI seems to show a slight improvement in Cstat when compared to isolated aspiration.

Effect of combined aerobic and resistance training on peak oxygen consumption, muscle strength and health-related quality of life in patients with heart failure with reduced left ventricular ejection fraction: a systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to investigate the effects of combined aerobic and resistance training on peak oxygen consumption (peak VO2), minute ventilation/carbon dioxide production (VE/VCO2 slope), muscle strength and health-related quality of life (HRQoL) in heart failure patients with reduced left ventricular ejection fraction (HFrEF). METHODS: We searched Cochrane, Pubmed, and PEDro (from the earliest date available to September 2018) for RCTs that evaluated the effects of combined aerobic and resistance training in HFrEF patients. Weighted mean differences (WMD), standardized mean difference (SMD), and 95% confidence interval (CI) were calculated. RESULTS: 39 studies met the study criteria, including 2008 patients, 14 compared combined aerobic and resistance training versus aerobic training, and 25 compared combined aerobic and resistance training versus control. Compared to aerobic training, combined aerobic and resistance training resulted in improvement in muscle strength SMD 0.7 (95% CI: 0.3 to 1.0 N = 167) and, HRQoL WMD -2.6 (95% CI: -5.0 to -0.1 N = 138). A nonsignificant difference in peak VO2 and VE/VCO2 slope was found for participants in the combined aerobic and resistance training group compared with aerobic training group. Compared to control, combined aerobic and resistance training resulted in improvement in peak VO2 WMD 2.9 (95% CI: 1.6 to 4.4 N = 638), muscle strength SMD 0.64 (95% CI: 0.4 to 0.9 N = 315) and, HRQoL WMD -9.8 (95% CI: -15.2 to -4.5 N = 524). CONCLUSIONS: Combined aerobic and resistance training improves peak VO2, muscle strength and HRQoL and should be considered as a component of care of HFrEF patients.

Lung and physical function in post COVID-19 and clinical and functional associations: a cross-sectional study in Brazil

SUMMARY OBJECTIVE: The purpose of this study was to assess exercise capacity, lung and physical function in COVID-19 survivors, and the association of lesion-level characteristics assessed by chest computed tomography, probable sarcopenia, and percentage of diffusing capacity of the lung for carbon monoxide with clinical and functional variables. METHODS: This study was conducted in Salvador, Bahia, Brazil. All patients had a laboratory-confirmed SARS-CoV-2 infection. The sociodemographic characteristics, COVID-19 exposure history, pulmonary function, computed tomography, and functionality of the participants between 1 and 3 months of diagnosis of the disease were collected. RESULTS: A total of 135 patients after COVID-19 recovery were included in this study. Probable sarcopenia, reduction in percentage of diffusing capacity of the lung for carbon monoxide, and a lower 6-min walk distance were observed after COVID-19 infection. Computed tomography>50% was associated with a longer length of stay and a lower percentage of diffusing capacity of the lung for carbon monoxide. Probable sarcopenia diagnosis was associated with a worse percentage of the predicted 6-min walk distance in relation to the predicted, absolute 6-min walk distance (m), percentage of diffusing capacity of the lung for carbon monoxide, and percentage of total lung capacity. CONCLUSION: Muscle disability and lung dysfunction are common in COVID-19 survivors. Hospitalization was associated with the worst muscle force and diffusing capacity of the lung for carbon monoxide. Computed tomography characteristics could be a marker of prolonged hospital stay after the acute phase of COVID-19. Additionally, the probable diagnosis of sarcopenia could be a marker of impact on walking distance. These results highlight the need for long-term follow-up of those patients and rehabilitation programs.

[Validation of the Brazilian version of Behavioral Pain Scale in adult sedated and mechanically ventilated patients]. / Validação da versão Brasileira da Escala Comportamental de Dor (Behavioral Pain Scale) em adultos sedados e sob ventilação mecânica.

BACKGROUND AND OBJECTIVES: The Behavioral Pain Scale is a pain assessment tool for uncommunicative and sedated Intensive Care Unit patients. The lack of a Brazilian scale for pain assessment in adults mechanically ventilated justifies the relevance of this study that aimed to validate the Brazilian version of Behavioral Pain Scale as well as to correlate its scores with the records of physiological parameters, sedation level and severity of disease. METHODS: Twenty-five Intensive Care Unit adult patients were included in this study. The Brazilian Behavioral Pain Scale version (previously translated and culturally adapted) and the recording of physiological parameters were performed by two investigators simultaneously during rest, during eye cleaning (non-painful stimulus) and during endotracheal suctioning (painful stimulus). RESULTS: High values of responsiveness coefficient (coefficient=3.22) were observed. The Cronbach's alpha of total Behavioral Pain Scale score at eye cleaning and endotracheal suctioning was 0.8. The intraclass correlation coefficient of total Behavioral Pain Scale score was ≥ 0.8 at eye cleaning and endotracheal suctioning. There was a significant highest Behavioral Pain Scale score during application of painful procedure when compared with rest period (p≤0.0001). However, no correlations were observed between pain and hemodynamic parameters, sedation level, and severity of disease. CONCLUSIONS: This pioneer validation study of Brazilian Behavioral Pain Scale exhibits satisfactory index of internal consistency, interrater reliability, responsiveness and validity. Therefore, the Brazilian Behavioral Pain Scale version was considered a valid instrument for being used in adult sedated and mechanically ventilated patients in Brazil.

Scales for the assessment of pain in the intensive care unit. Systematic review / Escalas para a avaliação da dor na unidade de terapia intensiva. Revisão sistemática

ABSTRACT BACKGROUND AND OBJECTIVES: Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Thus, pain is difficult to evaluate, especially in patients undergoing mechanical ventilation in an intensive care unit. However, there are several instruments to assess these patients' pain. Thus, the aims of the present study were described and characterize the psychometric characteristics of the intensive care unit pain assessment scales. CONTENTS: A systematic review in the electronic databases of Pubmed, LILACS, Cochrane Library and Scielo was performed, without time restrictions. The focus of this evidence synthesis is to examine the validity, reproducibility, and responsiveness of intensive care unit pain scales. 58 studies were included. Cronbach alpha ranged from 0.31 to 0.96 and the intraclass correlation coefficient from 0.25 to 1.00. A cross-cultural adaptation was performed in 28 studies for use in language Portuguese (Brazil), Chinese, Italian, Swedish, Portuguese (Portugal), English, Dutch, Turkish, Persian, Danish, Polish, Spanish and Greek. CONCLUSION: Among the available scales to measure pain in non-responsive patients, the data is not enough to indicate the superiority between them. In Brazil, most studies demonstrated that the pain scales had satisfactory validity, reliability, and reproducibility rates. Thus, when deciding which scale to use, the convenience of application and familiarity of the team should be considered.

RESUMO JUSTIFICATIVA E OBJETIVOS: A dor é considerada como uma experiência sensorial e emocional desagradável, associada a uma lesão efetiva ou potencial dos tecidos. Avaliar a dor é muito complexo, principalmente quando se trata de pacientes ventilados mecanicamente na unidade de terapia intensiva. No entanto, existem diversas escalas para avaliam a dor desses pacientes. Dessa forma, este estudo teve como objetivo sumarizar dados acerca das características psicométricas das escalas de avaliação de dor na unidade de terapia intensiva. CONTEÚDO: Foi realizada uma revisão sistemática através da pesquisa nas bases de dados Pubmed, LILACS, Cochrane Library e SciELO, foram incluídos os estudos que verificaram a confiabilidade, a validade, reprodutibilidade e a capacidade de resposta das escalas de avaliação de dor na unidade de terapia intensiva. Dos 58 estudos incluídos, o alfa de Cronbach variou de 0,31 a 0,96 e o coeficiente de correlação intraclasse variou de 0,25 a 1,00. Houve adaptação transcultural de 28 estudos nas versões brasileira, chinesa, italiana, sueca, portuguesa, inglesa, holandesa, turca, persa, dinamarquesa, polonesa, espanhola e grega. CONCLUSÃO: Os estudos publicados até o momento demonstraram uma lacuna para indicar a superioridade entre as escalas que avaliam dor em pacientes em ventilação mecânica. No Brasil, a maior parte dos estudos ressaltou que as escalas de avaliação da dor apresentam índices de validade, confiabilidade e reprodutibilidade satisfatórios. Assim, a decisão entre a escala a ser utilizada deve considerar facilidade de aplicação e a familiaridade da equipe.

Validation of the Brazilian version of Behavioral Pain Scale in adult sedated and mechanically ventilated patients / Validação da versão Brasileira da Escala Comportamental de Dor (Behavioral Pain Scale) em adultos sedados e sob ventilação mecânica

Abstract Background and objectives: The Behavioral Pain Scale is a pain assessment tool for uncommunicative and sedated Intensive Care Unit patients. The lack of a Brazilian scale for pain assessment in adults mechanically ventilated justifies the relevance of this study that aimed to validate the Brazilian version of Behavioral Pain Scale as well as to correlate its scores with the records of physiological parameters, sedation level and severity of disease. Methods: Twenty-five Intensive Care Unit adult patients were included in this study. The Brazilian Behavioral Pain Scale version (previously translated and culturally adapted) and the recording of physiological parameters were performed by two investigators simultaneously during rest, during eye cleaning (non-painful stimulus) and during endotracheal suctioning (painful stimulus). Results: High values of responsiveness coefficient (coefficient = 3.22) were observed. The Cronbach's alpha of total Behavioral Pain Scale score at eye cleaning and endotracheal suctioning was 0.8. The intraclass correlation coefficient of total Behavioral Pain Scale score was ≥ 0.8 at eye cleaning and endotracheal suctioning. There was a significant highest Behavioral Pain Scale score during application of painful procedure when compared with rest period (p ≤ 0.0001). However, no correlations were observed between pain and hemodynamic parameters, sedation level, and severity of disease. Conclusions: This pioneer validation study of Brazilian Behavioral Pain Scale exhibits satisfactory index of internal consistency, interrater reliability, responsiveness and validity. Therefore, the Brazilian Behavioral Pain Scale version was considered a valid instrument for being used in adult sedated and mechanically ventilated patients in Brazil.

Resumo Justificativa e objetivos: A Escala Comportamental de Dor (Behavioral Pain Scale) é uma ferramenta de avaliação da dor para pacientes não-comunicativos e sedados em unidade de tratamento intensivo (UTI). A falta de uma escala brasileira para a avaliação da dor em adultos sob ventilação mecânica justifica a relevância deste estudo que teve por objetivo validar a versão brasileira da Escala Comportamental de Dor (ECD), bem como correlacionar seus escores com os registros de parâmetros fisiológicos, nível de sedação e gravidade da doença. Métodos: Vinte e cinco pacientes adultos internados em UTI foram incluídos neste estudo. A versão brasileira da ECD (previamente traduzida e adaptada culturalmente) e os registros dos parâmetros fisiológicos foram realizados simultaneamente por dois avaliadores durante o repouso, durante a limpeza dos olhos (estímulo não doloroso) e durante a aspiração endotraqueal (estímulo doloroso). Resultados: Valores elevados do coeficiente de coeficiente de responsividade (coeficiente = 3,22) foram observados. O coeficiente alfa de Cronbach do escore total da ECD durante a limpeza dos olhos e aspiração endotraqueal foi de 0,8. O coeficiente de correlação intraclasse do escore total da ECD foi ≥ 0,8 durante a limpeza dos olhos e aspiração endotraqueal. Houve um escore significativamente mais alto na ECD durante a aplicação do estímulo doloroso em comparação com o período de descanso (p ≤ 0,0001). No entanto, não foram observadas correlações entre dor e parâmetros hemodinâmicos, nível de sedação e gravidade da doença. Conclusões: Este estudo pioneiro de validação da ECD brasileira apresenta índices satisfatórios de consistência interna, confiabilidade entre avaliadores, responsividade e validade. Portanto, a versão da ECD brasileira foi considerada um instrumento válido para ser usado em pacientes adultos sedados e ventilados mecanicamente no Brasil.

Experimental gestational hypothyroidism evokes hypertension in adult offspring rats.

Gestational hypothyroidism is a prevalent disorder in pregnant women. We aimed to investigate the impact of experimental gestational hypothyroidism (EGH) on cardiovascular and autonomic nervous systems (ANS) in the offspring of rats. EGH was induced with methimazole (MMI) 0.02% in drinking water from day 9 of gestation until birth. Sixty day old offspring from MMI-treated dams (OMTD, n=13) or water-treated dams (OWTD, n=13) had femoral arteries surgically assessed for the measurements of heart rate (HR), mean (MAP), systolic (SAP) and diastolic arterial pressure (DAP), and spontaneous baroreflex sensitivity (BRS). To investigate the balance of ANS, we established the high (HF) and low frequency (LF) bands of pulse interval (PI) and LF band of SAP spectrum. OMTD had increased MAP (130.2 ± 2.0 vs 108.8 ± 3.0 mmHg, p<0.001), SAP (157.3 ± 2.9 vs 135.7 ± 4.5mm Hg, p<0.001) and DAP (109.7 ± 1.9 vs 88.4 ± 2.6 mmHg, p<0.001) when compared to OWTD, and had lower HR (355.1 ± 8.9 vs 386.8 ± 9.2 bpm, p<0.05). After spectral analysis of PI and SAP, only LF band of SAP spectrum was higher (7.2 ± 0.8 vs 4.0 ± 0.6 mmHg(2), p<0.01) in OMTD under spontaneous condition. Despite bradycardia, EGH promotes spontaneous hypertension in 60 day old offspring, probably due to increased sympathetic modulation of vessels, which is suggested by the higher LF of SAP. These findings suggest a critical role of maternal THs in the development of fetal cardiovascular and autonomic nervous systems.