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1.
Br J Haematol ; 191(3): 390-393, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33037620

RESUMO

Critically ill patients with coronavirus disease 2019 (COVID-19) present with hypoxaemia and are mechanically ventilated to support gas exchange. We performed a retrospective, observational study of blood gas analyses (n = 3518) obtained from patients with COVID-19 to investigate changes in haemoglobin oxygen (Hb-O2 ) affinity. Calculated oxygen tension at half-saturation (p50 ) was on average (±SD) 3·3 (3·13) mmHg lower than the normal p50 value (23·4 vs. 26·7 mmHg; P < 0·0001). Compared to an unmatched historic control of patients with other causes of severe respiratory failure, patients with COVID-19 had a significantly higher Hb-O2 affinity (mean [SD] p50 23·4 [3·13] vs. 24·6 [5.4] mmHg; P < 0·0001). We hypothesise that, due to the long disease process, acclimatisation to hypoxaemia could play a role.


Assuntos
Betacoronavirus , Infecções por Coronavirus/sangue , Oxiemoglobinas/metabolismo , Pneumonia Viral/sangue , Adulto , Idoso , Dióxido de Carbono/sangue , Dispneia/sangue , Dispneia/etiologia , Feminino , Humanos , Concentração de Íons de Hidrogênio , Hipóxia/sangue , Hipóxia/etiologia , Masculino , Pessoa de Meia-Idade , Modelos Cardiovasculares , Oxigênio/sangue , Pandemias , Pressão Parcial , Estudos Retrospectivos
2.
PLoS One ; 15(9): e0238715, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32898150

RESUMO

Near-infrared spectroscopy (NIRS) is a non-invasive functional brain imaging technique. NIRS is suitable for monitoring brain activation during social interactions. One of the omnipresent social interactions for employees is saying thank you and being thanked. It has been demonstrated that expressing and receiving gratitude leads to employees' well-being and performance. To date, there have been no neuroimaging studies that monitor brain activity when receiving gratitude. Thus, we designed an experiment using NIRS to monitor brain function while listening to a letter of gratitude read by a coworker. We hypothesized that listening to a letter of gratitude read aloud by a co-worker in a face-to-face setting would have different effects on PFC activity than listening to a conversation about a neutral topic. We recruited 10 pairs of healthy right-handed employees. They were asked to write a letter of gratitude to their partner 1 week before the experiment. In the experiment, each pair sat face-to-face and read their letters aloud to each other. We evaluated changes in mood state before and after the experiment. NIRS was measured in each participant while they listened to their peers in the experimental condition (gratitude letter) and control condition (talking about the weather and date). The results suggested that negative mood state decreased after the experiment. Moreover, there were interaction effects between conditions and periods. Although further studies are needed to confirm the interpretation, our findings suggested that experience of being thanked was accompanied by prefrontal cortex activation.


Assuntos
Mapeamento Encefálico , Córtex Pré-Frontal/fisiologia , Leitura , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxiemoglobinas/metabolismo , Análise e Desempenho de Tarefas
3.
Am J Physiol Heart Circ Physiol ; 319(2): H468-H480, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32648821

RESUMO

Prolonged sitting, which is known to impair peripheral vascular function, often occurs in spaces (e.g., offices) with mild hypercapnic atmospheres. However, the effects of prolonged sitting in hypercapnic conditions on vascular function are unknown. Therefore, the purpose of this study was to investigate the effects of prolonged sitting in mild hypercapnic conditions on vascular and autonomic function in humans. Twelve healthy young adults participated in two experimental visits that consisted of sitting for 2.5 h in a control condition [normal atmospheric conditions sitting (PSIT)] or a mild hypercapnic condition (HCAP; CO2 = 1,500 ppm). During each visit, heart rate variability (HRV), blood pressure (BP), pulse wave velocity (PWV), augmentation index (AIx), brachial and popliteal artery flow-mediated dilation (FMD), and near-infrared spectroscopy (NIRS) were assessed before and after prolonged sitting. Sitting significantly decreased AIx in both groups (P < 0.05). Brachial and popliteal FMD were reduced with sitting (P < 0.05), and the reduction in popliteal FMD was amplified by HCAP (P < 0.05). Baseline microvascular oxygenation was decreased following sitting in both groups (P < 0.05). However, microvascular reoxygenation upon cuff release was slower only in HCAP (P < 0.05). HRV, HR, BP, and PWV did not significantly change with sitting in either group (P > 0.05). We conclude that prolonged sitting attenuated both brachial and popliteal endothelial function and was associated with perturbed microcirculation. Additionally, mild hypercapnic conditions further impaired peripheral endothelial and microvascular function. Together, these findings suggest that prolonged sitting is accompanied by a host of deleterious effects on the vasculature, which are exacerbated by mild hypercapnia.NEW & NOTEWORTHY The results of this study reveal that prolonged sitting attenuates endothelial function and microvascular function. Additionally, prolonged sitting with mild hypercapnia, which is similar to everyday environments, further exacerbates peripheral endothelial function and microvascular function.


Assuntos
Artéria Braquial/inervação , Hemodinâmica , Hipercapnia/fisiopatologia , Artéria Poplítea/inervação , Postura Sentada , Sistema Nervoso Simpático/fisiopatologia , Adulto , Pressão Arterial , Artéria Braquial/diagnóstico por imagem , Feminino , Frequência Cardíaca , Hemoglobinas/metabolismo , Humanos , Hipercapnia/sangue , Hipercapnia/diagnóstico por imagem , Masculino , Microcirculação , Oxiemoglobinas/metabolismo , Artéria Poplítea/diagnóstico por imagem , Fatores de Tempo , Rigidez Vascular , Adulto Jovem
5.
BMJ ; 369: m1501, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32434791

RESUMO

OBJECTIVE: To provide an overview and critical appraisal of early warning scores for adult hospital patients. DESIGN: Systematic review. DATA SOURCES: Medline, CINAHL, PsycInfo, and Embase until June 2019. ELIGIBILITY CRITERIA FOR STUDY SELECTION: Studies describing the development or external validation of an early warning score for adult hospital inpatients. RESULTS: 13 171 references were screened and 95 articles were included in the review. 11 studies were development only, 23 were development and external validation, and 61 were external validation only. Most early warning scores were developed for use in the United States (n=13/34, 38%) and the United Kingdom (n=10/34, 29%). Death was the most frequent prediction outcome for development studies (n=10/23, 44%) and validation studies (n=66/84, 79%), with different time horizons (the most frequent was 24 hours). The most common predictors were respiratory rate (n=30/34, 88%), heart rate (n=28/34, 83%), oxygen saturation, temperature, and systolic blood pressure (all n=24/34, 71%). Age (n=13/34, 38%) and sex (n=3/34, 9%) were less frequently included. Key details of the analysis populations were often not reported in development studies (n=12/29, 41%) or validation studies (n=33/84, 39%). Small sample sizes and insufficient numbers of event patients were common in model development and external validation studies. Missing data were often discarded, with just one study using multiple imputation. Only nine of the early warning scores that were developed were presented in sufficient detail to allow individualised risk prediction. Internal validation was carried out in 19 studies, but recommended approaches such as bootstrapping or cross validation were rarely used (n=4/19, 22%). Model performance was frequently assessed using discrimination (development n=18/22, 82%; validation n=69/84, 82%), while calibration was seldom assessed (validation n=13/84, 15%). All included studies were rated at high risk of bias. CONCLUSIONS: Early warning scores are widely used prediction models that are often mandated in daily clinical practice to identify early clinical deterioration in hospital patients. However, many early warning scores in clinical use were found to have methodological weaknesses. Early warning scores might not perform as well as expected and therefore they could have a detrimental effect on patient care. Future work should focus on following recommended approaches for developing and evaluating early warning scores, and investigating the impact and safety of using these scores in clinical practice. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017053324.


Assuntos
Cuidados Críticos/métodos , Hospitais/estatística & dados numéricos , Pacientes Internados/estatística & dados numéricos , Adulto , Idoso , Pressão Sanguínea , Deterioração Clínica , Cuidados Críticos/estatística & dados numéricos , Morte , Escore de Alerta Precoce , Feminino , Parada Cardíaca/epidemiologia , Frequência Cardíaca/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Oxiemoglobinas/metabolismo , Prognóstico , Taxa Respiratória/fisiologia , Temperatura , Reino Unido/epidemiologia , Estados Unidos/epidemiologia
6.
Microvasc Res ; 130: 104000, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32194082

RESUMO

INTRODUCTION: Impaired oxygenation in the skin may occur in disease states and after reconstructive surgery. We used tissue viability imaging (TiVi) to measure changes in oxygenation and deoxygenation of haemoglobin in an in vitro model and in the dermal microcirculation of healthy individuals. MATERIALS AND METHODS: Oxygenation was measured in human whole blood with different levels of oxygenation. In healthy subjects, changes in red blood cell concentration (CRBC,TiVi), oxygenation (ΔCOH,TiVi) and deoxygenation (ΔCDOH,TiVi) of haemoglobin were measured during and after arterial and venous occlusion using TiVi and were compared with measurements from the enhanced perfusion and oxygen saturation system (EPOS). RESULTS: During arterial occlusion, CRBC,TiVi remained unchanged while ΔCOH,TiVi decreased to -44.2 (10.4) AU (p = 0.04), as compared to baseline. After release, CRBC,TiVi increased to 39.2 (18.8) AU (p < 0.001), ΔCOH,TiVi increased to 38.5. During venous occlusion, CRBC,TiVi increased to 28.9 (11.2) AU (p < 0.001), ΔCOH,TiVi decreased to -52.2 (46.1) AU (p < 0.001) compared to baseline after 5 min of venous occlusion. There was a significant correlation between the TiVi Oxygen Mapper and EPOS, for arterial (r = 0.92, p < 0.001) and venous occlusion (r = 0.87, p < 0.001), respectively. CONCLUSION: This study shows that TiVi can measure trends in oxygenation and deoxygenation of haemoglobin during arterial and venous stasis in healthy individuals.


Assuntos
Hemoglobinas/metabolismo , Microcirculação , Oxiemoglobinas/metabolismo , Pele/irrigação sanguínea , Adulto , Velocidade do Fluxo Sanguíneo , Contagem de Eritrócitos , Feminino , Antebraço , Voluntários Saudáveis , Humanos , Hiperemia/fisiopatologia , Fluxometria por Laser-Doppler , Masculino , Fluxo Sanguíneo Regional , Análise Espectral , Fatores de Tempo , Adulto Jovem
7.
J Vasc Surg ; 72(2): 632-642, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32081480

RESUMO

OBJECTIVE: The objective of this study was to determine whether calf muscle hemoglobin oxygen saturation (Sto2) obtained during a standardized treadmill test is associated with ambulatory function and health-related quality of life (HRQoL) in patients with symptomatic peripheral artery disease (PAD). We hypothesized that a rapid decline in calf muscle Sto2 during walking is associated with impaired ambulatory function and HRQoL and that these associations are independent of ankle-brachial index (ABI). METHODS: Calf muscle Sto2, peak walking time, and claudication onset time were obtained during a treadmill test in 151 symptomatic men and women with PAD. Patients were further characterized by demographic variables, comorbid conditions, cardiovascular risk factors, ABI, 6-minute walk distance, daily ambulatory activity, Walking Impairment Questionnaire (WIQ) score, and Medical Outcomes Study 36-Item Short Form Health Survey physical function score to assess HRQoL. RESULTS: The median calf muscle Sto2 value at rest was 52%, which declined to 22% after only 1 minute of walking during the treadmill test and reached a minimum value of 9% after a median time of 87 seconds of walking. Of the various calf muscle Sto2 measurements obtained during the treadmill test, the exercise time to the minimum calf muscle Sto2 value (log transformed) had the strongest univariate associations with peak walking time (r = 0.56; P < .001), claudication onset time (r = 0.49; P < .001), 6-minute walk distance (r = 0.31; P < .001), WIQ distance score (r = 0.33; P < .001), WIQ speed score (r = 0.39; P < .001), WIQ stair-climbing score (r = 0.37; P < .001), and Medical Outcomes Study 36-Item Short Form Health Survey physical function score (r = 0.32; P < .001). In adjusted multiple regression models, these associations persisted (P < .001) after adjustment for demographic measures, cardiovascular risk factors, comorbid conditions, and ABI. CONCLUSIONS: More rapid decline in oxygen saturation of the calf musculature during walking, indicative of impaired microcirculation, is predictive of impaired ambulatory function and HRQoL in patients with symptomatic PAD. Of particular importance, these associations are independent of ABI and other common health burdens, highlighting the clinical relevance that the microcirculation has on ambulatory function and HRQoL in patients with symptomatic PAD.


Assuntos
Claudicação Intermitente/diagnóstico , Contração Muscular , Músculo Esquelético/irrigação sanguínea , Consumo de Oxigênio , Doença Arterial Periférica/diagnóstico , Qualidade de Vida , Teste de Caminhada , Caminhada , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice Tornozelo-Braço , Estudos Transversais , Tolerância ao Exercício , Feminino , Humanos , Claudicação Intermitente/sangue , Claudicação Intermitente/fisiopatologia , Extremidade Inferior , Masculino , Microcirculação , Pessoa de Meia-Idade , Oxiemoglobinas/metabolismo , Doença Arterial Periférica/sangue , Doença Arterial Periférica/fisiopatologia , Valor Preditivo dos Testes , Estudos Prospectivos , Inquéritos e Questionários , Fatores de Tempo
8.
J Sports Sci ; 38(7): 751-758, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32106780

RESUMO

Blood flow changes in response to exercise have been attributed, among other factors, to the effect of vasodilators factors on the microvasculature, suggesting a close relationship between small blood vessels and conducting arteries. The main purpose of this study was to determine the relationship between the changes in near infrared spectroscopy (NIRS)-derived total haemoglobin ([tHb]) and muscle oxygen saturation (SmO2) signals and femoral artery blood flow in response to resistance exercise at fast- and slow-velocity muscle contraction. The study randomised crossover design included twelve participants. NIRS and blood flow measurements were continuously monitored before, during, and 5 min after the exercise protocol. There was a significant correlation between [tHb] reperfusion slope ([tHb]slope) and peak blood flow (BFpeak) after slow- and fast-velocity muscle contraction (r = 0.83, p = 0.0008 and r = 0.72, p = 0.0080, respectively). No significant correlation existed between the SmO2 reperfusion slope (SmO2_slope) and BFpeak after both slow- and fast-velocity muscle contraction exercise (r = -0.46, p = 0.1253 and r = 0.33, p = 0.2841, respectively). This study demonstrated a strong relationship between the NIRS-derived [tHb] and Doppler ultrasound BF during the recovery period of dynamic resistance exercise at both slow- and fast-velocity contraction.


Assuntos
Hemoglobinas/metabolismo , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/diagnóstico por imagem , Oxiemoglobinas/metabolismo , Treinamento de Resistência/métodos , Espectroscopia de Luz Próxima ao Infravermelho , Velocidade do Fluxo Sanguíneo/fisiologia , Estudos Cross-Over , Artéria Femoral/fisiologia , Humanos , Hiperemia/fisiopatologia , Microcirculação/fisiologia , Contração Muscular/fisiologia , Consumo de Oxigênio/fisiologia , Fluxo Sanguíneo Regional , Ultrassonografia Doppler
9.
Anesth Analg ; 131(3): e138-e141, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-31985496

RESUMO

Regional cerebral oxygenation index (rSO2) based on near-infrared spectroscopy (NIRS) is frequently used to detect low venous oxyhemoglobin saturation (ScvO2). We compared the performance of 2 generations of NIRS devices. Clinically obtained, time-matched cerebral rSO2 and ScvO2 values were compared in infants monitored with the FORE-SIGHT (n = 73) or FORE-SIGHT ELITE (n = 47) by linear regression and Bland-Altman analyses. In both devices, cerebral rSO2 correlated poorly with measured ScvO2 (FORE-SIGHT partial correlation 0.50 [95% confidence interval {CI}, 0.40-0.58]; FORE-SIGHT ELITE partial correlation 0.47 [0.39-0.55]) and mean bias was +8 (standard deviation [SD] 13.2) for FORE-SIGHT and +14 (SD 12.5) for FORE-SIGHT ELITE. When ScvO2 was <30%, rSO2 was <40 in 8% of FORE-SIGHT ELITE readings. Future NIRS should be validated in more hypoxic cohorts.


Assuntos
Encéfalo/irrigação sanguínea , Procedimentos Cirúrgicos Cardíacos , Cardiopatias Congênitas/cirurgia , Hipóxia Encefálica/diagnóstico , Oximetria/instrumentação , Oxiemoglobinas/metabolismo , Espectroscopia de Luz Próxima ao Infravermelho/instrumentação , Biomarcadores/sangue , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Desenho de Equipamento , Humanos , Hipóxia Encefálica/sangue , Hipóxia Encefálica/etiologia , Recém-Nascido , Valor Preditivo dos Testes , Reprodutibilidade dos Testes
10.
Sci Rep ; 10(1): 845, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31964901

RESUMO

The invasive brown treesnake (Boiga irregularis) has extirpated much of Guam's native birdlife and poses significant threats to other parts of the western Pacific. Acetaminophen (APAP) is a proven lethal oral toxicant in reptiles but the physiological mechanism is unknown. The effects of a lethal APAP oral dose on methemoglobin (MetHb, non-oxygen carrying form) levels and other blood parameters were examined in brown treesnakes. Co-oximetry was used to measure MetHb (%) and other hemoglobin species. Assessment of red blood cell integrity, white blood cell differential counts, and plasma biochemical analyses were conducted to evaluate tissue damage, stress, and liver function. Changes in oxygen carrying capacity were noted in APAP-treated snakes indicated by a 50-60% increase in methemoglobin levels and a 40% decrease in oxyhemoglobin (oxygen-carrying form) levels compared to controls. APAP-treated snakes had decreased lymphocyte and increased monocyte counts while also having increased levels of blood analytes associate with impaired liver function and muscle damage. The proximate cause of death in APAP-treated snakes was likely acute methemoglobinemia and respiratory failure due to severe hypoxia with no observed signs of distress or pain. An orally-ingested lethal dose of APAP appears to be a humane method for lethal control of this species.


Assuntos
Acetaminofen/administração & dosagem , Acetaminofen/toxicidade , Ingestão de Alimentos , Metemoglobina/metabolismo , Controle Biológico de Vetores/métodos , Serpentes/sangue , Serpentes/metabolismo , Animais , Contagem de Células Sanguíneas , Oxiemoglobinas/metabolismo , Serpentes/fisiologia
11.
Adv Exp Med Biol ; 1232: 193-199, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893410

RESUMO

Measurement of oxyhemoglobin (O2Hb) changes in the cerebral cortex using near-infrared spectroscopy (NIRS) shows that its levels increase during moderate-intensity exercise and persists after exercise. However, the effects of exercise duration on O2Hb persistence in the premotor cortex (PMC) are unknown. We aimed to determine the effects of exercise duration on the persistence of O2Hb changes after moderate-intensity cycling as exercise. Healthy young volunteers were recruited to participate in this study. After a 3-min rest period, the exercise was initiated at a workload corresponding to 50% VO2peak. The exercise continued for 10 min and 20 min, followed by 15 min of rest. The O2Hb levels in the right (R-PMC) and left premotor cortices (L-PMC) were measured using an NIRS system. The O2Hb values during the 15-min post-exercise rest period in the R-PMC were 0.010 ± 0.011 mM·cm after the 10-min exercise and 0.035 ± 0.010 mM·cm after the 20-min exercise, without significant differences (p = 0.104). The O2Hb value in the L-PMC during post-exercise rest (0.055 ± 0.010 mM·cm) after the 20-min exercise was significantly higher than that after the 10-min exercise (0.023 ± 0.007 mM·cm; p = 0.014). Thus, the effects of exercise duration on O2Hb persistence have laterality in the PMC.


Assuntos
Exercício Físico , Córtex Motor , Consumo de Oxigênio , Oxiemoglobinas , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Feminino , Humanos , Masculino , Córtex Motor/metabolismo , Oxiemoglobinas/metabolismo , Fatores de Tempo , Adulto Jovem
12.
Adv Exp Med Biol ; 1232: 231-237, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893415

RESUMO

Near-infrared spectroscopy (NIRS) during cardiopulmonary exercise test (CPX) has shown a correlation between prefrontal cortex (PFC) oxygenated hemoglobin (O2Hb) level and negative affective responses. We hypothesized that O2Hb changes differ between the PFC and motor-related areas. This study investigated changes in hemoglobin levels in the PFC and motor-related areas during CPX. Twelve young healthy adults participated in this study. They performed a CPX after 4 min of rest and 4 min of warming up. Cortical O2Hb, deoxygenated hemoglobin (HHb), and total hemoglobin (THb) levels were measured with NIRS during CPX. Regions of interest (ROI) were the PFC, premotor area (PMA), supplementary motor area (SMA), and primary motor cortex (M1). The anaerobic threshold (AT), respiratory compensation (RC), and peak oxygen uptake (Peak) points were determined. The rest, AT, RC and Peak points of O2Hb, HHb, and THb were averaged over 5 s; hemoglobin slopes, from RC to the Peak points, were calculated to compare functional changes in cortical oxygenation. Average values of O2Hb, HHb, and THb in each ROI were compared among the rest, AT, RC, and Peak points. Average values of hemoglobin slopes, from RC to Peak points, were compared among ROIs using Bonferroni multiple comparisons. The HHb of all ROIs significantly increased at Peak point, compared with at the AT point. THb of the PFC, PMA, and SMA significantly increased at the RC or Peak points, compared with at the rest point. Hemoglobin slopes, from RC to Peak, showed no significant differences among ROIs. Each ROI exhibited similar changes, regardless of cortical function.


Assuntos
Córtex Motor , Oxigênio , Córtex Pré-Frontal , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Teste de Esforço , Feminino , Humanos , Masculino , Córtex Motor/metabolismo , Oxigênio/metabolismo , Consumo de Oxigênio , Oxiemoglobinas/metabolismo , Córtex Pré-Frontal/metabolismo , Adulto Jovem
13.
Adv Exp Med Biol ; 1232: 239-244, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893416

RESUMO

Near-infrared time-resolved spectroscopy (NIRTRS) can quantitatively evaluate mean optical path length (MPL). Since an increase in optical absorbers in the NIR region (e.g. an increase in deoxygenated hemoglobin during exercise) would shorten the MPL, the NIRS measurement area may vary depending on physical and physiological characteristics of the measurement region and/or the exercise intensity. The aim of this study was to examine the changes in MPL measured by NIRTRS during ramp cycling exercise between fat layer thickness-matched subjects with different aerobic capacities. Healthy control (CON, n = 8) and endurance-trained males (TR, n = 8) performed ramp cycling exercise until exhaustion. Deoxygenated hemoglobin concentration (Deoxy-Hb), total hemoglobin concentration (Total-Hb) and oxygenated hemoglobin concentration (Oxy-Hb) were evaluated by a three-wavelength NIRTRS system. MPL in each wavelength (MPL760, MPL800 and MPL830) was monitored continuously. With increasing exercise intensity, Total- and Deoxy-Hb significantly increased and Oxy-Hb decreased in both groups. Total- and Oxy-Hb during exercise were significantly higher in TR than CON (P < 0.05, P < 0.01, respectively). Furthermore, Deoxy-Hb also tended to be higher in TR than CON (P = 0.07). In addition, MPL at all wavelengths significantly shortened with an increase in exercise intensity, with no differences between CON and TR. In particular, MPL760 at peak exercise shortened more than 10% compared to the start of exercise in both groups, even though MPL830 decreased only a few per cent. These findings suggest that the NIRS measurement area may be reduced during ramp cycling exercise due to shortened MPL. Additionally, the changes in MPL may be especially greater at 760 nm than at the other wavelengths due to greater changes in Deoxy-Hb during exercise. Furthermore, this study indicates that the measurements of muscle deoxygenation using continuous-wave NIRS can be less accurate since they are significantly affected by changes in the optical path length.


Assuntos
Exercício Físico , Consumo de Oxigênio , Músculo Quadríceps , Adolescente , Adulto , Estudos de Casos e Controles , Teste de Esforço , Humanos , Masculino , Oxigênio/metabolismo , Oxiemoglobinas/metabolismo , Músculo Quadríceps/metabolismo , Espectroscopia de Luz Próxima ao Infravermelho , Adulto Jovem
14.
Adv Exp Med Biol ; 1232: 245-251, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893417

RESUMO

Skeletal muscle metabolic function is known to respond positively to endurance exercise interventions, such as marathon training. Studies investigating skeletal muscle have typically used muscle biopsy samples or magnetic resonance spectroscopy (MRS) to interrogate metabolic function. We aimed to non-invasively detect exercise-training-induced improvements in muscle function using broadband near-infrared spectroscopy (NIRS). We used NIRS to determine concentration changes in oxygenated haemoglobin (HbO2) and the oxidation state of cytochrome-c-oxidase (oxCCO) in gastrocnemius during arterial occlusion in 14 volunteers. We also used a cardio-pulmonary exercise test (CPET) to assess peak total body oxygen uptake (peakVO2; a measure of fitness). Measurements were made at baseline (BL) which was prior to a period of at least 16 weeks of training for the 2017 London Marathon, and then within 3 weeks after completion of the marathon, follow-up (FU). We observed an increase in locally measured muscle oxygen consumption and rate of oxCCO concentration change, but not in cardio-respiratory fitness measured as whole-body peak oxygen consumption (peakVO2).


Assuntos
Músculo Esquelético , Consumo de Oxigênio , Corrida , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Humanos , Masculino , Músculo Esquelético/metabolismo , Oxiemoglobinas/metabolismo
15.
Adv Exp Med Biol ; 1232: 331-337, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893428

RESUMO

Obesity, a risk factor of coronary artery disease, is known to cause peripheral microcirculatory disturbances. This study evaluated the relationship between the degree of obesity and peripheral microcirculatory disturbances, using peripheral near infrared spectroscopy (NIRS) with a vascular occlusion test (VOT). We compared correlations between the NIRS parameter changes induced by VOT and body mass index (BMI) in patients with and without statin therapy. A NIRS probe was set on the right thenar eminence, brachial artery blood flow was blocked for 3 min, and then released. Although total hemoglobin (ΔcHb), deoxyhemoglobin (ΔHHb) and tissue oxygenation index (ΔTOI) were not correlated with BMI, a significant negative correlation was found between oxyhemoglobin (ΔO2Hb) and BMI in the overall study population (r = -0.255, p-value 0.02). In addition, a significant negative correlation was found between ΔO2Hb and BMI in patients without statin therapy (r = -0.353, p-value 0.02) but not in patients with statin therapy (r = -0.181, p-value 0.27). These findings suggest that ΔO2Hb may be a useful indicator to assess peripheral microcirculation.


Assuntos
Índice de Massa Corporal , Doença da Artéria Coronariana , Espectroscopia de Luz Próxima ao Infravermelho , Idoso , Feminino , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Masculino , Microcirculação/fisiologia , Oxigênio , Consumo de Oxigênio , Oxiemoglobinas/metabolismo , Fatores de Risco , Espectroscopia de Luz Próxima ao Infravermelho/normas
16.
Adv Exp Med Biol ; 1232: 355-360, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893431

RESUMO

Epicardial adipose tissue (EAT) is associated with visceral fat and various cardiac disorders, such as atrial fibrillation and adverse cardiovascular events. Therefore, it is important to develop a simple and non-invasive inspection method to assess EAT, to prevent unfavorable cardiac events. This study assessed correlations between near-infrared spectroscopy (NIRS) changes induced by a vascular occlusion test (VOT) and EAT volume measured by cardiac computed tomography (CCT) in patients with suspected coronary artery disease. We also assessed correlations between body mass index (BMI) and EAT volume in the same population. In addition, these correlations were compared in patients treated with statin therapy and in those without statin therapy. A NIRS probe was set on the right thenar eminence, and brachial artery blood flow was blocked for 3 min before being released. A negative correlation was found between oxyhemoglobin (ΔO2Hb) and EAT volume in the overall study population (r = -0.236, p = 0.03). Interestingly, although a strong correlation was observed in patients without statin therapy (r = -0.488, p < 0.001), this correlation was not observed in patients with statin therapy (r = 0.157, p = 0.34). These findings suggest that NIRS measurements with VOT may be a useful method to identify patients with high EAT volume and high cardiovascular risks.


Assuntos
Doença da Artéria Coronariana , Espectroscopia de Luz Próxima ao Infravermelho , Tecido Adiposo/metabolismo , Idoso , Índice de Massa Corporal , Angiografia por Tomografia Computadorizada , Doença da Artéria Coronariana/diagnóstico , Feminino , Humanos , Masculino , Oxiemoglobinas/metabolismo , Fatores de Risco
17.
Br J Anaesth ; 124(1): 110-120, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31767144

RESUMO

BACKGROUND: We aimed to examine whether using a high fraction of inspired oxygen (FIO2) in the context of an individualised intra- and postoperative open-lung ventilation approach could decrease surgical site infection (SSI) in patients scheduled for abdominal surgery. METHODS: We performed a multicentre, randomised controlled clinical trial in a network of 21 university hospitals from June 6, 2017 to July 19, 2018. Patients undergoing abdominal surgery were randomly assigned to receive a high (0.80) or conventional (0.3) FIO2 during the intraoperative period and during the first 3 postoperative hours. All patients were mechanically ventilated with an open-lung strategy, which included recruitment manoeuvres and individualised positive end-expiratory pressure for the best respiratory-system compliance, and individualised continuous postoperative airway pressure for adequate peripheral oxyhaemoglobin saturation. The primary outcome was the prevalence of SSI within the first 7 postoperative days. The secondary outcomes were composites of systemic complications, length of intensive care and hospital stay, and 6-month mortality. RESULTS: We enrolled 740 subjects: 371 in the high FIO2 group and 369 in the low FIO2 group. Data from 717 subjects were available for final analysis. The rate of SSI during the first postoperative week did not differ between high (8.9%) and low (9.4%) FIO2 groups (relative risk [RR]: 0.94; 95% confidence interval [CI]: 0.59-1.50; P=0.90]). Secondary outcomes, such as atelectasis (7.7% vs 9.8%; RR: 0.77; 95% CI: 0.48-1.25; P=0.38) and myocardial ischaemia (0.6% [n=2] vs 0% [n=0]; P=0.47) did not differ between groups. CONCLUSIONS: An oxygenation strategy using high FIO2 compared with conventional FIO2 did not reduce postoperative SSIs in abdominal surgery. No differences in secondary outcomes or adverse events were found. CLINICAL TRIAL REGISTRATION: NCT02776046.


Assuntos
Oxigênio/uso terapêutico , Respiração Artificial/métodos , Infecção da Ferida Cirúrgica/prevenção & controle , Abdome/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxigênio/sangue , Oxiemoglobinas/análise , Oxiemoglobinas/metabolismo , Assistência Perioperatória , Respiração com Pressão Positiva , Medicina de Precisão , Atelectasia Pulmonar/epidemiologia , Atelectasia Pulmonar/etiologia , Resultado do Tratamento
18.
Lasers Med Sci ; 35(3): 641-649, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31420794

RESUMO

Exposure of biological tissue to photobiomodulation therapy (PBMT) seems to increase the oxygen availability and mitochondrial electrochemical activity. With the advancement of new technologies, such as near-infrared spectroscopy (NIRS), information can be obtained about the balance between oxygen utilization and delivery by assessing local oxy- ([O2Hb]) and deoxy-myohemoglobin ([HHb]) concentrations, both measured in micromolars (µM). Consequently, NIRS can be used to study ("in vivo") PBMT effects on the oxidative system, including oxygen availability. Thus, the main objective of the present study was to use NIRS to investigate the acute effects of PBMT by light-emitting diode (LED) on the oxygen delivery and utilization in humans. Twelve healthy young participants were treated with a LED device (850 nm, 50 mW, 2 J) and placebo applied over the proximal third of the flexor carpi ulnaris muscle of the left or right forearm selected in a random order. The LED was applied in direct contact with skin and the device was switched on for 40 s in 4 different interventions (I1, I2, I3 and I4) with a 3-min interval between interventions. The placebo condition was considered as the period before the first PBMT. The NIRS device was used to evaluate the relative changes in [O2Hb] and [HHb] before and after placebo and interventions. We found that PBMT statistically increased the [O2Hb] in 0.39 µM. These results demonstrate the potential of PBMT to increase oxygen availability.


Assuntos
Hemoglobinas/metabolismo , Terapia com Luz de Baixa Intensidade , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Humanos , Masculino , Músculo Esquelético/fisiologia , Oxiemoglobinas/metabolismo , Placebos
20.
Circ Res ; 126(1): 129-158, 2020 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-31590598

RESUMO

A continuous supply of oxygen is essential for the survival of multicellular organisms. The understanding of how this supply is regulated in the microvasculature has evolved from viewing erythrocytes (red blood cells [RBCs]) as passive carriers of oxygen to recognizing the complex interplay between Hb (hemoglobin) and oxygen, carbon dioxide, and nitric oxide-the three-gas respiratory cycle-that insures adequate oxygen and nutrient delivery to meet local metabolic demand. In this context, it is blood flow and not blood oxygen content that is the main driver of tissue oxygenation by RBCs. Herein, we review the lines of experimentation that led to this understanding of RBC function; from the foundational understanding of allosteric regulation of oxygen binding in Hb in the stereochemical model of Perutz, to blood flow autoregulation (hypoxic vasodilation governing oxygen delivery) observed by Guyton, to current understanding that centers on S-nitrosylation of Hb (ie, S-nitrosohemoglobin; SNO-Hb) as a purveyor of oxygen-dependent vasodilatory activity. Notably, hypoxic vasodilation is recapitulated by native S-nitrosothiol (SNO)-replete RBCs and by SNO-Hb itself, whereby SNO is released from Hb and RBCs during deoxygenation, in proportion to the degree of Hb deoxygenation, to regulate vessels directly. In addition, we discuss how dysregulation of this system through genetic mutation in Hb or through disease is a common factor in oxygenation pathologies resulting from microcirculatory impairment, including sickle cell disease, ischemic heart disease, and heart failure. We then conclude by identifying potential therapeutic interventions to correct deficits in RBC-mediated vasodilation to improve oxygen delivery-steps toward effective microvasculature-targeted therapies. To the extent that diseases of the heart, lungs, and blood are associated with impaired tissue oxygenation, the development of new therapies based on the three-gas respiratory system have the potential to improve the well-being of millions of patients.


Assuntos
Dióxido de Carbono/sangue , Fenômenos Fisiológicos Cardiovasculares , Hemoglobinas/metabolismo , Óxido Nítrico/sangue , Oxigênio/sangue , Regulação Alostérica , Animais , Transfusão de Sangue , Sequência Conservada , Cisteína/metabolismo , Células Endoteliais/fisiologia , Eritrócitos/metabolismo , Hemoglobinas/genética , Hemoglobinas Anormais/metabolismo , Humanos , Hipóxia/fisiopatologia , Mamíferos/sangue , Microcirculação , Modelos Cardiovasculares , Oxiemoglobinas/metabolismo , Doença Arterial Periférica/sangue , Doença Arterial Periférica/fisiopatologia , S-Nitrosotióis/análise , S-Nitrosotióis/sangue , Vasodilatação/fisiologia
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