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1.
Exp Physiol ; 109(10): 1728-1738, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39120591

RESUMO

Neck pain associated with helmet-wear is an occupational health problem often observed in helicopter pilots and aircrew. Whether aircrew helmet wearing is associated with physiological and biomechanical differences between sexes is currently unknown. This study investigated neuromuscular activation patterns during different helmet-wearing conditions. The helmet load was manipulated through a novel Helmet Balancing System (HBS) in healthy, non-pilot male and female participants (n = 10 each, age 19-45 years) in two phases. Phase A assessed the acute effects of helmet-wear on neck muscles activation during head movements. Phase B examined changes in muscle activity and cervical disc height after wearing a helmet for 45 min. In Phase A, muscle activity was similar between sexes in many movements, but it was higher in female participants when wearing a helmet than in males. The HBS reduced muscle activity in both sexes. In Phase B, female participants exhibited a greater level of muscular fatigue, and male participants' cervical disc height was significantly decreased [5.7 (1.4) vs. 4.4 (1.5) mm, P < 0.001] after continuous wearing. Both sexes showed no significant change in muscle fatigue and disc height [male: 5.0 (1.3) vs. 5.2 (1.4) mm, P = 0.604] after applying HBS. These findings demonstrate sex-specific physiological and biomechanical responses to wearing a helmet. They may indicate different postural and motor control strategies, associated with different neck pain aetiologies in male and female aircrew, the knowledge of which is important to reduce or prevent musculoskeletal injuries associated with helmet wearing.


Assuntos
Dispositivos de Proteção da Cabeça , Fadiga Muscular , Músculos do Pescoço , Humanos , Feminino , Masculino , Músculos do Pescoço/fisiologia , Adulto , Fadiga Muscular/fisiologia , Pessoa de Meia-Idade , Vértebras Cervicais , Adulto Jovem , Caracteres Sexuais , Cervicalgia/fisiopatologia , Fenômenos Biomecânicos/fisiologia , Eletromiografia
2.
Retina ; 2024 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-39121498

RESUMO

PURPOSE: The approach to managing patients with retinal vein occlusion (RVO) and cystoid macular edema (CME) with good initial visual acuity (VA) better than 6/12 has not been investigated. This study aimed to evaluate functional and anatomical outcomes of intravitreal treatment and observation in patients with CME due to RVO, who presented with good initial VA. Methods: Multicenter retrospective cohort study. Seventy-nine eyes of 79 patients with CME secondary to RVO and initial VA better than 6/12, either treated with anti-VEGF therapy or observed. Clinical parameters and OCT measures were recorded. Main Outcome Measure: Proportion of patients losing ≥1 line of VA at 12 months. Secondary outcomes: Visual and anatomical results at 12 and 24 months, and correlation between number of injections and VA outcomes. RESULTS: Fifty-three percent of patients maintained VA at month 12. VA of 6/6 - 6/7.5 was maintained in 59% and 57% at 12 and 24 months, respectively. At 24 months, the number of anti-VEGF injections was strongly correlated with VA among patients with BRVO and CRVO. CONCLUSION: This study marks the first exploration of patients with RVO and initial VA better than 6/12, indicating that most patients sustained good VA, and anti-VEGF treatment maintained and improved VA.

3.
Ophthalmologica ; : 1-22, 2024 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-39357510

RESUMO

BACKGROUND: The aim of this study was to investigate demographic, anatomical, angiographic and functional parameters in patients suffering from polypoidal choroidal vasculopathy (PCV). METHODS: 60 eyes of 60 patients with a definite diagnosis of treatment-naïve exudative monolateral PCV were evaluated in this retrospective study. The fellow eyes and age-matched healthy subjects were enrolled as comparison. All subjects underwent a complete ophthalmic evaluation with multimodal imaging assessment, including spectral domain (SD) optical coherence tomography (OCT) and OCT angiography (OCTA). Main outcome measures in the comparison analysis were central macular thickness (CMT), subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI), whereas Outcome measures for correlation analyses were best corrected visual acuity (BCVA), intraretinal fluid (IRF) and sub retinal fluid (SRF) presence, SRF thickness (SRFT), vascularized pigmented epithelial detachment (VPED) height, and PCV outer retina to choriocapillaris (ORCC) flow area (ORCCFA). RESULTS: CVI was significantly higher in affected and fellow eyes if compared with the healthy ones (p=0.049; p=0.003). Subfoveal choroid resulted to be thicker in the diseased eyes when compared with healthy ones (p=0.002). A negative correlation was assessed between age and SFCT, CMT and BCVA. In addition, a significant association between male gender and anatomical and functional parameters has been found with male prevalence at baseline in cases. No association between systemic conditions and PCV features was found. CONCLUSIONS: Patients with monolater PCV show choroidal changes in terms of higher values of CVI, also in fellow eyes, that were negatively related with age. In our cohort of patients males showed the poorest diagnosis with a baseline lower BCVA and higher CMT when compared with females. PCV was not associated with any systemic condition.

4.
Ophthalmic Res ; 67(1): 528-536, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39236688

RESUMO

INTRODUCTION: The aim of the study was to evaluate functional and anatomical changes in patients with neovascular age-related macular degeneration (nAMD) treated with a loading dose of faricimab intravitreal injections (IVIs). METHODS: Eighteen eyes of 18 patients with active macular neovascularization and nAMD were enrolled at the Ophthalmology Clinic of University G. D'Annunzio, Chieti-Pescara, Italy. All patients were scheduled for faricimab IVI as per label. Enrolled patients underwent complete ophthalmic evaluation, including optical coherence tomography, fluorescein angiography, and indocyanine green angiography. All measurements were evaluated at baseline (T0) and then monthly up to week 20 (T4). Main outcome measures were changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), subfoveal choroidal thickness (SFCT), pigment epithelial detachments (PEDs) presence and maximum height (PED-MH), intraretinal fluid (IRF) presence, subfoveal subretinal fluid (SSRF) presence and thickness. RESULTS: BCVA improved and CMT reduced significantly during follow-up (p < 0.001). In addition, SFCT decreased significantly (p = 0.031). Between T0 and T4, SSRF presence reduced from 55.6 to 16.7% (p = 0.045); IRF presence changed from 50 to 22.2%, respectively (p = 0.074). PED-MH was reduced in 58.8% of patients at T4. At week 20, 72.3% of patients were in the q12/q16 interval. CONCLUSION: Faricimab showed efficacy in the treatment of naïve nAMD patients with an improvement of anatomical and functional parameters and a treatment interval after the loading phase equal or greater than 12 weeks in the majority of patients.


Assuntos
Inibidores da Angiogênese , Angiofluoresceinografia , Injeções Intravítreas , Tomografia de Coerência Óptica , Acuidade Visual , Degeneração Macular Exsudativa , Humanos , Masculino , Feminino , Tomografia de Coerência Óptica/métodos , Idoso , Angiofluoresceinografia/métodos , Degeneração Macular Exsudativa/tratamento farmacológico , Degeneração Macular Exsudativa/diagnóstico , Degeneração Macular Exsudativa/fisiopatologia , Idoso de 80 Anos ou mais , Resultado do Tratamento , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/uso terapêutico , Seguimentos , Fundo de Olho , Estudos Prospectivos , Macula Lutea/patologia , Macula Lutea/diagnóstico por imagem
5.
N Engl J Med ; 382(9): 835-844, 2020 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-32101665

RESUMO

Mutations in VHL, which encodes von Hippel-Lindau tumor suppressor (VHL), are associated with divergent diseases. We describe a patient with marked erythrocytosis and prominent mitochondrial alterations associated with a severe germline VHL deficiency due to homozygosity for a novel synonymous mutation (c.222C→A, p.V74V). The condition is characterized by early systemic onset and differs from Chuvash polycythemia (c.598C→T) in that it is associated with a strongly reduced growth rate, persistent hypoglycemia, and limited exercise capacity. We report changes in gene expression that reprogram carbohydrate and lipid metabolism, impair muscle mitochondrial respiratory function, and uncouple oxygen consumption from ATP production. Moreover, we identified unusual intermitochondrial connecting ducts. Our findings add unexpected information on the importance of the VHL-hypoxia-inducible factor (HIF) axis to human phenotypes. (Funded by Associazione Italiana Ricerca sul Cancro and others.).


Assuntos
Mutação em Linhagem Germinativa , Transtornos do Crescimento/genética , Hipoglicemia/genética , Fator 1 Induzível por Hipóxia/deficiência , Mitocôndrias/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Expressão Gênica , Crescimento/genética , Humanos , Masculino , Metaboloma/genética , Metaboloma/fisiologia , Síndrome , Adulto Jovem
6.
Br J Anaesth ; 130(1): e44-e46, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-34903360

RESUMO

Patient self-inflicted lung injury may be associated with worse clinical outcomes and higher mortality. Patient-ventilator asynchrony is associated with increased ventilator days and mortality, and it has been hypothesised as one of the important mechanisms leading to patient self-inflicted lung injury. However, given the observational nature of the key studies in the field so far, the hypothesis that patient-ventilator asynchrony causes patient self-inflicted lung injury has not been supported by evidence yet. Wittenstein and colleagues present a novel approach that enables controlling patient-ventilator asynchrony in a pig model of acute lung injury, to investigate the patient-ventilator asynchrony and patient self-inflicted lung injury causality. Their results suggest that increased patient-ventilator asynchrony associated with poor clinical outcomes reported in observational trials could be a marker, rather than a cause of patient self-inflicted lung injury. These findings on their own are not sufficient to justify a greater tolerance of patient-ventilator asynchrony amongst clinicians, a change for which further experimental work and clinical evidence is needed.


Assuntos
Lesão Pulmonar Aguda , Pulmão , Suínos , Animais , Ventiladores Mecânicos , Lesão Pulmonar Aguda/etiologia , Respiração Artificial/efeitos adversos , Respiração Artificial/métodos
7.
Exp Physiol ; 107(7): 683-693, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-34541721

RESUMO

NEW FINDINGS: What is the topic of this review? This review presents the fundamental concepts of respiratory physiology and pathophysiology, with particular reference to lung mechanics and the pulmonary phenotype associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and subsequent coronavirus disease 2019 (COVID-19) pneumonia. What advances does it highlight? The review provides a critical summary of the main physiological aspects to be considered for safe and effective mechanical ventilation in patients with severe COVID-19 in the intensive care unit. ABSTRACT: Severe respiratory failure from coronavirus disease 2019 (COVID-19) pneumonia not responding to non-invasive respiratory support requires mechanical ventilation. Although ventilation can be a life-saving therapy, it can cause further lung injury if airway pressure and flow and their timing are not tailored to the respiratory system mechanics of the individual patient. The pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to a pattern of lung injury in patients with severe COVID-19 pneumonia typically associated with two distinct phenotypes, along a temporal and pathophysiological continuum, characterized by different levels of elastance, ventilation-to-perfusion ratio, right-to-left shunt, lung weight and recruitability. Understanding the underlying pathophysiology, duration of symptoms, radiological characteristics and lung mechanics at the individual patient level is crucial for the appropriate choice of mechanical ventilation settings to optimize gas exchange and prevent further lung injury. By critical analysis of the literature, we propose fundamental physiological and mechanical criteria for the selection of ventilation settings for COVID-19 patients in intensive care units. In particular, the choice of tidal volume should be based on obtaining a driving pressure < 14 cmH2 O, ensuring the avoidance of hypoventilation in patients with preserved compliance and of excessive strain in patients with smaller lung volumes and lower lung compliance. The level of positive end-expiratory pressure (PEEP) should be informed by the measurement of the potential for lung recruitability, where patients with greater recruitability potential may benefit from higher PEEP levels. Prone positioning is often beneficial and should be considered early. The rationale for the proposed mechanical ventilation settings criteria is presented and discussed.


Assuntos
COVID-19/terapia , Lesão Pulmonar/virologia , Respiração Artificial , Síndrome do Desconforto Respiratório/virologia , SARS-CoV-2 , COVID-19/fisiopatologia , Humanos , Unidades de Terapia Intensiva/normas , Lesão Pulmonar/terapia , Respiração Artificial/efeitos adversos , Respiração Artificial/normas , Síndrome do Desconforto Respiratório/terapia , Mecânica Respiratória/fisiologia , Volume de Ventilação Pulmonar/fisiologia
8.
Curr Opin Crit Care ; 28(1): 9-16, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34907979

RESUMO

PURPOSE OF REVIEW: More than 230 million people have tested positive for severe acute respiratory syndrome-coronavirus-2 infection globally by September 2021. The infection affects primarily the function of the respiratory system, where ∼20% of infected individuals develop coronavirus-19 disease (COVID-19) pneumonia. This review provides an update on the pathophysiology of the COVID-19 acute lung injury. RECENT FINDINGS: In patients with COVID-19 pneumonia admitted to the intensive care unit, the PaO2/FiO2 ratio is typically <26.7 kPa (200 mmHg), whereas lung volume appears relatively unchanged. This hypoxaemia is likely determined by a heterogeneous mismatch of pulmonary ventilation and perfusion, mainly associated with immunothrombosis, endothelialitis and neovascularisation. During the disease, lung weight, elastance and dead space can increase, affecting respiratory drive, effort and dyspnoea. In some severe cases, COVID-19 pneumonia may lead to irreversible pulmonary fibrosis. SUMMARY: This review summarises the fundamental pathophysiological features of COVID-19 in the context of the respiratory system. It provides an overview of the key clinical manifestations of COVID-19 pneumonia, including gas exchange impairment, altered pulmonary mechanics and implications of abnormal chemical and mechanical stimuli. It also critically discusses the clinical implications for mechanical ventilation therapy.


Assuntos
Lesão Pulmonar Aguda , COVID-19 , Humanos , Pulmão , Respiração Artificial/efeitos adversos , SARS-CoV-2 , Tromboinflamação
9.
Br J Anaesth ; 128(2): 343-351, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34772497

RESUMO

BACKGROUND: Artificial intelligence (AI) has the potential to personalise mechanical ventilation strategies for patients with respiratory failure. However, current methodological deficiencies could limit clinical impact. We identified common limitations and propose potential solutions to facilitate translation of AI to mechanical ventilation of patients. METHODS: A systematic review was conducted in MEDLINE, Embase, and PubMed Central to February 2021. Studies investigating the application of AI to patients undergoing mechanical ventilation were included. Algorithm design and adherence to reporting standards were assessed with a rubric combining published guidelines, satisfying the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis [TRIPOD] statement. Risk of bias was assessed by using the Prediction model Risk Of Bias ASsessment Tool (PROBAST), and correspondence with authors to assess data and code availability. RESULTS: Our search identified 1,342 studies, of which 95 were included: 84 had single-centre, retrospective study design, with only one randomised controlled trial. Access to data sets and code was severely limited (unavailable in 85% and 87% of studies, respectively). On request, data and code were made available from 12 and 10 authors, respectively, from a list of 54 studies published in the last 5 yr. Ethnicity was frequently under-reported 18/95 (19%), as was model calibration 17/95 (18%). The risk of bias was high in 89% (85/95) of the studies, especially because of analysis bias. CONCLUSIONS: Development of algorithms should involve prospective and external validation, with greater code and data availability to improve confidence in and translation of this promising approach. TRIAL REGISTRATION NUMBER: PROSPERO - CRD42021225918.


Assuntos
Inteligência Artificial , Respiração Artificial/métodos , Insuficiência Respiratória/terapia , Algoritmos , Viés , Humanos , Modelos Teóricos , Ensaios Clínicos Controlados Aleatórios como Assunto , Projetos de Pesquisa , Relatório de Pesquisa/normas
10.
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 , COVID-19 , 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 , SARS-CoV-2
11.
Crit Care Med ; 48(3): e200-e208, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31809278

RESUMO

OBJECTIVES: Determine the intra-tidal regional gas and blood volume distributions at different levels of atelectasis in experimental lung injury. Test the hypotheses that pulmonary aeration and blood volume matching is reduced during inspiration in the setting of minimal tidal recruitment/derecruitment and that this mismatching is an important determinant of hypoxemia. DESIGN: Preclinical study. SETTING: Research laboratory. SUBJECTS: Seven anesthetized pigs 28.7 kg (SD, 2.1 kg). INTERVENTIONS: All animals received a saline-lavage surfactant depletion lung injury model. Positive end-expiratory pressure was varied between 0 and 20 cm H2O to induce different levels of atelectasis. MEASUREMENTS AND MAIN RESULTS: Dynamic dual-energy CT images of a juxtadiaphragmatic slice were obtained, gas and blood volume fractions within three gravitational regions calculated and normalized to lung tissue mass (normalized gas volume and normalized blood volume, respectively). Ventilatory conditions were grouped based upon the fractional atelectatic mass in expiration (< 20%, 20-40%, and ≥ 40%). Tidal recruitment/derecruitment with fractional atelectatic mass in expiration greater than or equal to 40% was less than 7% of lung mass. In this group, inspiration-related increase in normalized gas volume was greater in the nondependent (818 µL/g [95% CI, 729-908 µL/g]) than the dependent region (149 µL/g [120-178 µL/g]). Normalized blood volume decreased in inspiration in the nondependent region (29 µL/g [12-46 µL/g]) and increased in the dependent region (39 µL/g [30-48 µL/g]). Inspiration-related changes in normalized gas volume and normalized blood volume were negatively correlated in fractional atelectatic mass in expiration greater than or equal to 40% and 20-40% groups (r = 0.56 and 0.40), but not in fractional atelectatic mass in expiration less than 20% group (r = 0.01). Both the increase in normalized blood volume in the dependent region and fractional atelectatic mass in expiration negatively correlated with PaO2/FIO2 ratio (ρ = -0.77 and -0.93, respectively). CONCLUSIONS: In experimental atelectasis with minimal tidal recruitment/derecruitment, mechanical inspiratory breaths redistributed blood volume away from well-ventilated areas, worsening PaO2/FIO2.


Assuntos
Lesão Pulmonar/terapia , Respiração com Pressão Positiva/efeitos adversos , Atelectasia Pulmonar/terapia , Circulação Pulmonar/fisiologia , Respiração Artificial/métodos , Algoritmos , Animais , Modelos Animais de Doenças , Mecânica Respiratória , Suínos , Volume de Ventilação Pulmonar
12.
Exp Physiol ; 105(4): 606-612, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32189419

RESUMO

NEW FINDINGS: What is the topic for this review? This review summarizes recent discoveries in mitochondrial development and morphology studied with electron microscopy. What advances does it highlight? Although mitochondria are generally considered to be isolated from each other, this review highlights recently discovered evidence for the presence of intermitochondrial communication structures in cardiac and skeletal muscle, in animal models and humans. Within striated muscles, the means of intermitochondrial exchange and the reaction of mitochondria to external stimuli are uniquely dependent on the tissue, and we clearly differentiate between nanotunnels, the active protrusion of cardiac mitochondria, and the connecting ducts of skeletal muscle derived from fusion-fission and elongation events. ABSTRACT: This review focuses on recent discoveries in skeletal and cardiac muscles indicating that mitochondria behave as an interactive cohort with inter-organelle communication and specific reactions to stress signals. Our new finding is that intermitochondrial communications in cardiac and skeletal muscles rely on two distinct methods. In cardiac muscle, mitochondria are discrete entities and are fairly well immobilized in a structural context. The organelles have developed a unique method of communication, via nanotunnels, which allow temporary connection from one mitochondrion to another over distances of up to several micrometres, without overall movement of the individual organelles and loss of their identity. Skeletal muscle mitochondria, in contrast, are dynamic. Through fusion, fission and elongation, they form connections that include constrictions and connecting ducts (distinct from nanotunnels) and lose individual identity in the formation of extensive networks. Connecting elements in skeletal muscle are distinct from nanotunnels in cardiac muscle.


Assuntos
Coração/fisiologia , Mitocôndrias Cardíacas/fisiologia , Mitocôndrias Musculares/fisiologia , Músculo Esquelético/fisiologia , Animais , Humanos , Miocárdio
13.
Br J Anaesth ; 124(3): 345-353, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31952649

RESUMO

BACKGROUND: Bedside lung volume measurement could personalise ventilation and reduce driving pressure in patients with acute respiratory distress syndrome (ARDS). We investigated a modified gas-dilution method, the inspired sinewave technique (IST), to measure the effective lung volume (ELV) in pigs with uninjured lungs and in an ARDS model. METHODS: Anaesthetised mechanically ventilated pigs were studied before and after surfactant depletion by saline lavage. Changes in PEEP were used to change ELV. Paired measurements of absolute ELV were taken with IST (ELVIST) and compared with gold-standard measures (sulphur hexafluoride wash in/washout [ELVSF6] and computed tomography (CT) [ELVCT]). Measured volumes were used to calculate changes in ELV (ΔELV) between PEEP levels for each method (ΔELVIST, ΔELVSF6, and ΔELVCT). RESULTS: The coefficient of variation was <5% for repeated ELVIST measurements (n=13 pigs). There was a strong linear relationship between ELVIST and ELVSF6 in uninjured lungs (r2=0.97), and with both ELVSF6 and ELVCT in the ARDS model (r2=0.87 and 0.92, respectively). ELVIST had a mean bias of -12 to 13% (95% limits=±17 - 25%) compared with ELVSF6 and ELVCT. ΔELVIST was concordant with ΔELVSF6 and ΔELVCT in 98-100% of measurements, and had a mean bias of -73 to -77 ml (95% limits=±128 - 186 ml) compared with ΔELVSF6 and -1 ml (95% limits ±333 ml) compared with ΔELVCT. CONCLUSIONS: IST provides a repeatable measure of absolute ELV and shows minimal bias when tracking PEEP-induced changes in lung volume compared with CT in a saline-lavage model of ARDS.


Assuntos
Respiração com Pressão Positiva/métodos , Síndrome do Desconforto Respiratório/terapia , Animais , Modelos Animais de Doenças , Medidas de Volume Pulmonar/métodos , Testes Imediatos , Reprodutibilidade dos Testes , Síndrome do Desconforto Respiratório/diagnóstico por imagem , Síndrome do Desconforto Respiratório/etiologia , Síndrome do Desconforto Respiratório/fisiopatologia , Solução Salina , Sus scrofa , Tomografia Computadorizada por Raios X
14.
Br J Anaesth ; 123(2): 126-134, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30954237

RESUMO

BACKGROUND: Cardiac output (Q˙) monitoring can support the management of high-risk surgical patients, but the pulmonary artery catheterisation required by the current 'gold standard'-bolus thermodilution (Q˙T)-has the potential to cause life-threatening complications. We present a novel noninvasive and fully automated method that uses the inspired sinewave technique to continuously monitor cardiac output (Q˙IST). METHODS: Over successive breaths the inspired nitrous oxide (N2O) concentration was forced to oscillate sinusoidally with a fixed mean (4%), amplitude (3%), and period (60 s). Q˙IST was determined in a single-compartment tidal ventilation lung model that used the resulting amplitude/phase of the expired N2O sinewave. The agreement and trending ability of Q˙IST were compared with Q˙T during pharmacologically induced haemodynamic changes, before and after repeated lung lavages, in eight anaesthetised pigs. RESULTS: Before lung lavage, changes in Q˙IST and Q˙T from baseline had a mean bias of -0.52 L min-1 (95% confidence interval [CI], -0.41 to -0.63). The concordance between Q˙IST and Q˙T was 92.5% as assessed by four-quadrant analysis, and polar plot analysis revealed a mean angular bias of 5.98° (95% CI, -24.4°-36.3°). After lung lavage, concordance was slightly reduced (89.4%), and the mean angular bias widened to 21.8° (-4.2°, 47.6°). Impaired trending ability correlated with shunt fraction (r=0.79, P<0.05). CONCLUSIONS: The inspired sinewave technique provides continuous and noninvasive monitoring of cardiac output, with a 'marginal-good' trending ability compared with cardiac output based on thermodilution. However, the trending ability can be reduced with increasing shunt fraction, such as in acute lung injury.


Assuntos
Débito Cardíaco , Monitorização Fisiológica/métodos , Animais , Modelos Animais , Óxido Nitroso , Suínos , Termodiluição/métodos
15.
Int J Sports Med ; 40(5): 305-311, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30736073

RESUMO

The aim of this study was to assess the changes determined by increased cadence on skeletal muscle oxygenation during cycling at an exercise intensity equal to the ventilatory threshold (Tvent).Nine healthy, active individuals with different levels of cycling experience exercised at a power output equal to Tvent, pedaling at cadences of 40, 50, 60, 70, 80 and 90 rpm, each for 4 min. Cadences were tested in a randomized counterbalanced sequence. Cardiopulmonary and metabolic responses were studied using an ECG for heart rate, and gas calorimetry for pulmonary oxygen uptake and carbon dioxide production. NIRS was used to determine the tissue saturation index (TSI), a measure of vastus lateralis oxygenation.TSI decreased from rest to exercise; the magnitude of this TSI reduction was significantly greater when pedaling at 90 rpm (-14±4%), compared to pedaling at 40 (-12±3%) and 50 (-12±3%) rpm (P=0.027 and 0.017, respectively). Albeit small, the significant decrease in ΔTSI at increased cadence recorded in this study suggests that skeletal muscle oxygenation is relatively more affected by high cadence when exercise intensity is close to Tvent.


Assuntos
Ciclismo/fisiologia , Músculo Esquelético/fisiologia , Consumo de Oxigênio , Adulto , Feminino , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Pessoa de Meia-Idade , Adulto Jovem
18.
J Physiol ; 594(5): 1197-213, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-25907672

RESUMO

Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8-h isocapnic exposure to hypoxia (end-tidal P(O2)=55 Torr) in a purpose-built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (G(pO2)) and hyperoxic hypercapnia, the latter divided into peripheral (G(pCO2)) and central (G(cCO2)) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For G(pO2), G(pCO2) and G(cC O2), but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre-acclimatization value. Additionally, the change in G(pO2) during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G(pCO2) predicted the subsequent rise in ventilation and change in G(pO2) during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G(pCO2) is a modest predictor of ventilatory acclimatization.


Assuntos
Aclimatação , Altitude , Pressão Sanguínea , Hipóxia/fisiopatologia , Artéria Pulmonar/fisiologia , Ventilação Pulmonar , Adolescente , Adulto , Dióxido de Carbono/metabolismo , Feminino , Humanos , Hipóxia/etiologia , Masculino , Pessoa de Meia-Idade , Oxigênio/metabolismo
20.
Blood ; 123(3): 366-76, 2014 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-24196071

RESUMO

Neutrophil lifespan and function are regulated by hypoxia via components of the hypoxia inducible factor (HIF)/von Hippel Lindau/hydroxylase pathway, including specific roles for HIF-1α and prolyl hydroxylase-3. HIF-2α has both distinct and overlapping biological roles with HIF-1α and has not previously been studied in the context of neutrophil biology. We investigated the role of HIF-2α in regulating key neutrophil functions. Human and murine peripheral blood neutrophils expressed HIF-2α, with expression up-regulated by acute and chronic inflammatory stimuli and in disease-associated inflammatory neutrophil. HIF2A gain-of-function mutations resulted in a reduction in neutrophil apoptosis both ex vivo, through the study of patient cells, and in vivo in a zebrafish tail injury model. In contrast, HIF-2α-deficient murine inflammatory neutrophils displayed increased sensitivity to nitrosative stress induced apoptosis ex vivo and increased neutrophil apoptosis in vivo, resulting in a reduction in neutrophilic inflammation and reduced tissue injury. Expression of HIF-2α was temporally dissociated from HIF-1α in vivo and predominated in the resolution phase of inflammation. These data support a critical and selective role for HIF-2α in persistence of neutrophilic inflammation and provide a platform to dissect the therapeutic utility of targeting HIF-2α in chronic inflammatory diseases.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação da Expressão Gênica , Inflamação , Neutrófilos/metabolismo , Animais , Apoptose , Hipóxia Celular , Proteínas de Fluorescência Verde/metabolismo , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Muramidase , Neutrófilos/citologia , Fagocitose , Fenótipo , RNA/metabolismo , Explosão Respiratória , Peixe-Zebra
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