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2.
Best Pract Res Clin Anaesthesiol ; 35(4): 543-549, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34801216

RESUMO

Oxygen delivery is dependent on pulmonary gas exchange, cardiac output, blood oxygen-carrying capacity, and tissue oxygen extraction. Reduction in oxygen delivery or higher oxygen consumption can initiate complex protective cellular processes precipitating oxygen debt. In critically ill and potentially surgical patients, stress and consequent hormonal or metabolic changes can trigger oxygen debt which is associated with worse morbidity and mortality. Increase in oxygen delivery by augmenting cardiac output or by increasing fraction of inspired oxygen (FiO2) can help reduce oxygen debt. However, the extent of oxygen debt in an individual patient is poorly defined and difficult to measure. Furthermore, large heterogeneity in clinical trials assessing outcomes benefit of increasing oxygen delivery limits our ability to recommend goal directed fluid therapy aimed at increasing cardiac ouput or higher FiO2. To understand and prevent oxygen debt in critically ill and surgical patients, we need to develop continuous monitoring techniques to assess the balance of oxygen delivery and consumption. Furthermore, methods of increasing oxygen delivery like goal-directed fluid therapy, higher FiO2 and anemia prevention should be rigorously evaluated with focus on establishing outcomes benefit.


Assuntos
Consumo de Oxigênio , Troca Gasosa Pulmonar , Débito Cardíaco , Estado Terminal , Humanos , Oxigênio
3.
Zhongguo Ying Yong Sheng Li Xue Za Zhi ; 37(2): 120-124, 2021 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-34672148

RESUMO

Objective: To observe the effect of healthy volunteers different work rate increasing rate cardiopulmonary exercise testing (CPET) on the sub-peak parameters . Methods: Twelve healthy volunteers were randomly assigned to a moderate (30 W/min), a relatively low (10 W/min) and relatively high (60 W/min) three different work rate increasing rate CPET on different working days in a week. The core indicators related to CPET sub-peak exercise of 12 volunteers were compared according to standard Methods: anaerobic threshold (AT), oxygen uptake per unit power (ΔVO2/ΔWR), oxygen uptake eficiency plateau,(OUEP), the lowest average of 90 s of carbon dioxide ventilation equivalent (Lowest VE/ VCO2), the slope of carbon dioxide ventilation equivalent (VE/ VCO2 Slope) and intercept and anaerobic threshold oxygen uptake ventilation efficiency value (VO2/ VE@AT) and the anaerobic threshold carbon dioxide ventilation equivalent value (VE/ VCO2@AT). Paired t test was performed on the difference of each parameter in the three groups of different work rate increasing rate. Results: Compared with the relatively low and relatively high work rate increasing rate group, the moderate work rate increasing rate group uptake eficiency plateau, (42.22±4.76 vs 39.54±3.30 vs 39.29±4.29) and the lowest average of 90 s of carbon dioxide ventilation equivalent (24.13±2.88 vs 25.60±2.08 vs 26.06±3.05) was significantly better, and the difference was statistically significant (P<0.05); Compared with the moderate work rate increasing rate group, the oxygen uptake per unit work rate of the relatively low and relatively high work rate increasing rate group increased and decreased significantly ((8.45±0.66 vs 10.04±0.58 vs 7.16±0.60) ml/(min·kg)), difference of which was statistically significant (P<0.05); the anaerobic threshold did not change significantly ((0.87±0.19 vs 0.87±0.19 vs 0.89±0.19) L/min), the difference was not statistically significant (P>0.05). Conclusion: Relatively low and relatively high power increase rate can significantly change the CPET sub-peak sports related indicators such as the effectiveness of oxygen uptake ventilation, the effectiveness of carbon dioxide exhaust ventilation, and the oxygen uptake per unit work rate. Compared with the moderate work rate increasing rate CPET, the lower and higher work rate increasing rate significantly reduces the effectiveness of oxygen uptake ventilation and the effectiveness of carbon dioxide exhaust ventilation in healthy individuals. The standardized operation of CPET requires the selection of a work rate increasing rate suitable for the subject, so that the CPET sub-peak related indicators can best reflect the true functional state of the subject.


Assuntos
Teste de Esforço , Consumo de Oxigênio , Limiar Anaeróbio , Humanos , Troca Gasosa Pulmonar , Ventilação Pulmonar
4.
Respir Care ; 66(10): 1610-1617, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34465571

RESUMO

BACKGROUND: Persistent impairment of pulmonary function and exercise capacity has been known to last for months or even years in the survivors who recovered from other coronavirus pneumonia. Some reports showed that subjects with coronavirus disease 2019 pneumonia after being discharged could have several sequelae, but there are few studies on gas exchange and exercise capacity complications in these subjects. AIMS: To describe residual gas exchange abnormalities during recovery from coronavirus disease 2019 pneumonia. METHODS: In an observational study, ∼90 d after onset of disease, we scheduled almost 200 subjects for an out-patient visit with pulmonary function testing and computed tomography of the lungs. Lung mechanics by using body plethysmography, gas exchange with diffusing lung capacity for carbon monoxide determined by the single-breath technique (DLCOsb) and diffusing lung capacity for nitric oxide determined by the single-breath technique (DLNOsb), and exercise ability by using the 6-min walk test (6MWT) were measured in the subjects. The results were compared between those who required invasive mechanical ventilation and those who did not. RESULTS: A total of 171 subjects were included, the majority (96%) had signs of residual pneumonia (such as an excess of high attenuation areas) on computed tomography of the lungs. The DLCOSB results were below the lower limit of the normal range in 29.2% of the subjects; during the 6MWT, 67% experienced oxygen desaturation ([Formula: see text]) > 4%; and, in 81 (47%), the dropped below 88%. Subjects who required invasive mechanical ventilation (49.7%) were more likely to have lower lung volumes, more gas exchange abnormality, less exercise capacity and more radiologic abnormality. CONCLUSIONS: Subjects who recovered from severe COVID-19 pneumonia continued to have abnormal lung function and abnormal radiologic findings.


Assuntos
COVID-19 , Humanos , Pulmão/diagnóstico por imagem , Capacidade de Difusão Pulmonar , Troca Gasosa Pulmonar , Testes de Função Respiratória , SARS-CoV-2 , Teste de Caminhada
5.
Medicine (Baltimore) ; 100(36): e27020, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34516492

RESUMO

INTRODUCTION: The study aimed to reveal how the fraction of inspired oxygen (FIO2) affected the value of mixed venous oxygen saturation (SvO2) and the accuracy of Fick-equation-based cardiac output (Fick-CO). METHODS: Forty two adult patients who underwent elective cardiac surgery were enrolled and randomly divided into 2 groups: FIO2 < 0.7 or >0.85. Under stable general anesthesia, thermodilution-derived cardiac output (TD-CO), SvO2, venous partial pressure of oxygen, hemoglobin, arterial oxygen saturation, arterial partial pressure of oxygen, and blood pH levels were recorded before surgical incision. RESULTS: Significant differences in FIO2 values were observed between the 2 groups (0.56 ±â€Š0.08 in the <70% group and 0.92 ±â€Š0.03 in the >0.85 group; P < .001). The increasing FIO2 values lead to increases in SvO2, venous partial pressure of oxygen, and arterial partial pressure of oxygen, with little effects on cardiac output and hemoglobin levels. When comparing to TD-CO, the calculated Fick-CO in both groups had moderate Pearson correlations and similar linear regression results. Although the FIO2 <0.7 group presented a less mean bias and a smaller limits of agreement, neither group met the percentage error criteria of <30% in Bland-Altman analysis. CONCLUSION: Increased FIO2 may influence the interpretation of SvO2 and the exacerbation of Fick-CO estimation, which could affect clinical management. TRIAL REGISTRATION: ClinicalTrials.gov ID number: NCT04265924, retrospectively registered (Date of registration: February 9, 2020).


Assuntos
Débito Cardíaco , Procedimentos Cirúrgicos Cardíacos , Oxigênio/sangue , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Período Pós-Operatório , Estudos Prospectivos , Troca Gasosa Pulmonar , Adulto Jovem
6.
Sci Rep ; 11(1): 17862, 2021 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-34504252

RESUMO

When hemoglobin (Hb) is fully saturated with oxygen, the additional gain in oxygen delivery (DO2) achieved by increasing the fraction of inspired oxygen (FiO2) is often considered clinically insignificant. In this study, we evaluated the change in DO2, interrogated by mixed venous oxygen saturation (SvO2), in response to a change in FiO2 of 0.5 during cardiac surgery. When patients were hemodynamically stable, FiO2 was alternated between 0.5 and 1.0 in on-pump cardiac surgery patients (pilot study), and between 0.3 and 0.8 in off-pump coronary artery bypass grafting patients (substudy of the CARROT trial). After the patient had stabilized, a blood gas analysis was performed to measure SvO2. The observed change in SvO2 (ΔSvO2) was compared to the expected ΔSvO2 calculated using Fick's equation. A total 106 changes in FiO2 (two changes per patient; total 53 patients; on-pump, n = 36; off-pump, n = 17) were finally analyzed. While Hb saturation remained near 100% (on-pump, 100%; off-pump, mean [SD] = 98.1% [1.5] when FiO2 was 0.3 and 99.9% [0.2] when FiO2 was 0.8), SvO2 changed significantly as FiO2 was changed (the first and second changes in on-pump, 7.7%p [3.8] and 7.6%p [3.5], respectively; off-pump, 7.9%p [4.9] and 6.2%p [3.9]; all P < 0.001). As a total, regardless of the surgery type, the observed ΔSvO2 after the FiO2 change of 0.5 was ≥ 5%p in 82 (77.4%) changes and ≥ 10%p in 31 (29.2%) changes (mean [SD], 7.5%p [3.9]). Hb concentration was not correlated with the observed ΔSvO2 (the first changes, r = - 0.06, P = 0.677; the second changes, r = - 0.21, P = 0.138). The mean (SD) residual ΔSvO2 (observed - expected ΔSvO2) was 0%p (4). Residual ΔSvO2 was more than 5%p in 14 (13.2%) changes and exceeded 10%p in 2 (1.9%) changes. Residual ΔSvO2 was greater in patients with chronic kidney disease than in those without (median [IQR], 5%p [0 to 7] vs. 0%p [- 3 to 2]; P = 0.049). DO2, interrogated by SvO2, may increase to a clinically significant degree as FiO2 is increased during cardiac surgery, and the increase of SvO2 is not related to Hb concentration. SvO2 increases more than expected in patients with chronic kidney disease. Increasing FiO2 can be used to increase DO2 during cardiac surgery.


Assuntos
Débito Cardíaco/fisiologia , Consumo de Oxigênio/fisiologia , Oxigênio/sangue , Troca Gasosa Pulmonar/fisiologia , Cirurgia Torácica , Idoso , Gasometria/métodos , Ponte de Artéria Coronária sem Circulação Extracorpórea/métodos , Daucus carota/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oximetria/métodos
7.
Br J Anaesth ; 127(5): 807-814, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34507822

RESUMO

BACKGROUND: Lung rest has been recommended during extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS). Whether positive end-expiratory pressure (PEEP) confers lung protection during ECMO for severe ARDS is unclear. We compared the effects of three different PEEP levels whilst applying near-apnoeic ventilation in a model of severe ARDS treated with ECMO. METHODS: Acute respiratory distress syndrome was induced in anaesthetised adult male pigs by repeated saline lavage and injurious ventilation for 1.5 h. After ECMO was commenced, the pigs received standardised near-apnoeic ventilation for 24 h to maintain similar driving pressures and were randomly assigned to PEEP of 0, 10, or 20 cm H2O (n=7 per group). Respiratory and haemodynamic data were collected throughout the study. Histological injury was assessed by a pathologist masked to PEEP allocation. Lung oedema was estimated by wet-to-dry-weight ratio. RESULTS: All pigs developed severe ARDS. Oxygenation on ECMO improved with PEEP of 10 or 20 cm H2O, but did not in pigs allocated to PEEP of 0 cm H2O. Haemodynamic collapse refractory to norepinephrine (n=4) and early death (n=3) occurred after PEEP 20 cm H2O. The severity of lung injury was lowest after PEEP of 10 cm H2O in both dependent and non-dependent lung regions, compared with PEEP of 0 or 20 cm H2O. A higher wet-to-dry-weight ratio, indicating worse lung injury, was observed with PEEP of 0 cm H2O. Histological assessment suggested that lung injury was minimised with PEEP of 10 cm H2O. CONCLUSIONS: During near-apnoeic ventilation and ECMO in experimental severe ARDS, 10 cm H2O PEEP minimised lung injury and improved gas exchange without compromising haemodynamic stability.


Assuntos
Oxigenação por Membrana Extracorpórea/métodos , Lesão Pulmonar/fisiopatologia , Respiração com Pressão Positiva/métodos , Síndrome do Desconforto Respiratório/terapia , Animais , Modelos Animais de Doenças , Hemodinâmica , Masculino , Troca Gasosa Pulmonar/fisiologia , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório/fisiopatologia , Índice de Gravidade de Doença , Suínos
8.
Am J Physiol Regul Integr Comp Physiol ; 321(5): R712-R722, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-34431402

RESUMO

This study tested the hypothesis that the respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme]BP, assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at the same metabolic rate in the upright (U) and supine (S) body positions. Eleven healthy men completed ramp incremental exercise tests in U and S. Gas exchange was measured breath-by-breath and time-resolved-NIRS was used to measure deoxy[heme] in the vastus lateralis (VL) and rectus femoris (RF). RCP (S: 2.56 ± 0.39, U: 2.86 ± 0.40 L·min-1, P = 0.02) differed from deoxy[heme]BP in the VL in U (3.10 ± 0.44 L·min-1, P = 0.002), but was not different in S in the VL (2.70 ± 0.50 L·min-1, P = 0.15). RCP was not different from the deoxy[heme]BP in the RF for either position (S: 2.34 ± 0.48 L·min-1, U: 2.76 ± 0.53 L·min-1, P > 0.05). However, the deoxy[heme]BP differed between muscles in both positions (P < 0.05), and changes in deoxy[heme]BP did not relate to ΔRCP between positions (VL: r = 0.55, P = 0.080, RF: r = 0.26, P = 0.44). The deoxy[heme]BP was consistently preceded by a breakpoint in total[heme], and was, in turn, itself preceded by a breakpoint in muscle surface electromyography (EMG). RCP and the deoxy[heme]BP can be dissociated across muscles and different body positions and, therefore, do not represent the same underlying physiological phenomenon. The deoxy[heme]BP may, however, be mechanistically related to breakpoints in total[heme] and muscle activity.


Assuntos
Metabolismo Energético , Exercício Físico , Hemoglobinas/metabolismo , Contração Muscular , Mioglobina/sangue , Consumo de Oxigênio , Troca Gasosa Pulmonar , Músculo Quadríceps/metabolismo , Decúbito Dorsal , Adolescente , Adulto , Biomarcadores/sangue , Eletromiografia , Voluntários Saudáveis , Humanos , Masculino , Espectroscopia de Luz Próxima ao Infravermelho , Fatores de Tempo , Adulto Jovem
10.
Nutrients ; 13(7)2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34209600

RESUMO

The relation between changes in respiratory quotient (RQ) following dietary interventions and clinical parameters and body fat pools remains unknown. In this randomized controlled trial, participants with moderate abdominal obesity or/and dyslipidemia (n = 159) were randomly assigned to a Mediterranean/low carbohydrate (MED/LC, n = 80) or a low fat (LF, n = 79) isocaloric weight loss diet and completed a metabolic assessment. Changes in RQ (measured by indirect calorimeter), adipose-tissue pools (MRI), and clinical measurements were assessed at baseline and after 6 months of intervention. An elevated RQ at baseline was significantly associated with increased visceral adipose tissue, hepatic fat, higher levels of insulin and homeostatic insulin resistance. After 6 months, body weight had decreased similarly between the diet groups (-6 ± 6 kg). However, the MED/LC diet, which greatly improved metabolic health, decreased RQ significantly more than the LF diet (-0.022 ± 0.007 vs. -0.002 ± 0.008, p = 0.005). Total cholesterol and diastolic blood pressure were independently associated with RQ changes (p = 0.045). RQ was positively associated with increased superficial subcutaneous-adipose-tissue but decreased renal sinus, pancreatic, and intramuscular fats after adjusting for confounders. Fasting RQ may reflect differences in metabolic characteristics between subjects affecting their potential individual response to the diet.


Assuntos
Tecido Adiposo/fisiopatologia , Dieta Redutora/métodos , Obesidade Abdominal/dietoterapia , Troca Gasosa Pulmonar/fisiologia , Perda de Peso/fisiologia , Adulto , Calorimetria Indireta , Dieta com Restrição de Carboidratos/métodos , Dieta com Restrição de Gorduras/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade Abdominal/fisiopatologia , Resultado do Tratamento
11.
Inflamm Res ; 70(8): 847-858, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34286362

RESUMO

BACKGROUND: Recognizing only sharp elevation in a short period of time, the COVID-19 SARS-CoV-2 propagation is more and more marked in the whole world. Induced inflammation afterwards infection engenders a high infiltration of immune cells and cytokines that triggers matrix metalloproteinases (MMPs) activation. These endopeptidases are mediators of the lung extracellular matrix (ECM), a basic element for alveoli structure and gas exchange. METHODS: When immune cells, MMPs, secreted cytokines and several other mediators are gathered a pathological matrix remodeling occurs. This phenomenon tends to tissue destruction in the first place and a pulmonary hypertrophy and fibrosis in the second place. FINDINGS: After pathological matrix remodeling establishment, pathological diseases take place even after infection state. Since post COVID-19 pulmonary fibrosis is an emerging complication of the disease, there is an urge to better understand and characterize the implication of ECM remodeling during SARS-CoV-2 infection. CONCLUSION: Targeting MMPs and their inhibitors could be a probable solution for occurred events since there are many cured patients that remain with severe sequels even after the end of infection.


Assuntos
COVID-19/imunologia , COVID-19/virologia , Matriz Extracelular/metabolismo , Metaloproteinases da Matriz/metabolismo , SARS-CoV-2 , Comunicação Celular , Linhagem da Célula , Citocinas/metabolismo , Citoplasma/metabolismo , Fibrose/imunologia , Homeostase , Humanos , Hipertrofia , Sistema Imunitário , Interferon gama/metabolismo , Pulmão/fisiopatologia , Alvéolos Pulmonares/metabolismo , Fibrose Pulmonar , Troca Gasosa Pulmonar
13.
Clin Respir J ; 15(11): 1229-1238, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34328695

RESUMO

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe respiratory disease with a high mortality rate. It is characterized by acute onset of pulmonary edema, hypoxemia, and the need of mechanical ventilation. As the primary treatment, ventilation has been considered effective in treating patients with ARDS. Recently, numerous studies have shown that prone position ventilation demonstrates more efficacy compared with traditional supine position. However, the potential impact of the non-physiological prone position on patients remains unclear. Current study aims to evaluate the effect of prone position ventilation on right heart function in ARDS patients. METHODS: Following Berlin Diagnostic Criteria, 80 eligible patients were recruited and randomly assigned into prone position ventilation group and supine position ventilation group. Different ventilation methods were implemented in these two groups. RESULTS: Both positions showed the beneficial effects, as evidenced by decreased PV score and APACHE II score, enhanced blood gas index and right heart function parameters, and the prognosis analysis. However, compared with those receiving SPV treatment, the patients demonstrated greater benefits from PPV treatment, with significant differences in PV score (p < 0.01) and APACHE II score (p < 0.001), blood gas index such as PAPm (p < 0.05), and right heart function indicators (p < 0.05). CONCLUSION: Prone position mechanical ventilation is more beneficial than supine position ventilation in improving the blood gas status of patients with moderate to severe ARDS, and it is more helpful to reduce the load on the right heart and promote the recovery of patients.


Assuntos
Síndrome do Desconforto Respiratório , Humanos , Pulmão , Decúbito Ventral , Troca Gasosa Pulmonar , Respiração Artificial , Síndrome do Desconforto Respiratório/diagnóstico , Síndrome do Desconforto Respiratório/terapia
14.
Radiology ; 301(1): 211-220, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34313473

RESUMO

Background Recent studies demonstrate that antifibrotic drugs previously reserved for idiopathic pulmonary fibrosis (IPF) may slow progression in other interstitial lung diseases (ILDs), creating an urgent need for tools that can sensitively assess disease activity, progression, and therapy response across ILDs. Hyperpolarized xenon 129 (129Xe) MRI and spectroscopy have provided noninvasive measurements of regional gas-exchange abnormalities in IPF. Purpose To assess gas exchange function using 129Xe MRI in a group of study participants with nonspecific interstitial pneumonia (NSIP) compared with healthy control participants. Materials and Methods In this prospective study, participants with NSIP and healthy control participants were enrolled between November 2017 and February 2020 and underwent 129Xe MRI and spectroscopy. Quantitative imaging provided three-dimensional maps of ventilation, interstitial barrier uptake, and transfer into the red blood cell (RBC) compartment. Spectroscopy provided parameters of the static RBC and barrier uptake compartments, as well as cardiogenic oscillations in RBC signal amplitude and chemical shift. Differences between NSIP and healthy control participants were assessed using the Wilcoxon rank-sum test. Results Thirty-six participants with NSIP (mean age, 57 years ± 11 [standard deviation]; 27 women) and 15 healthy control participants (mean age, 39 years ± 18; two women) were evaluated. Participants with NSIP had no difference in ventilation compared with healthy control participants (median, 4.4% [first quartile, 1.5%; third quartile, 8.7%] vs 6.0% [first quartile, 2.8%; third quartile, 6.9%]; P = .91), but they had a higher barrier uptake (median, 6.2% [first quartile, 1.8%; third quartile, 23.9%] vs 0.53% [first quartile, 0.33%; third quartile, 2.9%]; P = .003) and an increased RBC transfer defect (median, 20.6% [first quartile, 11.6%; third quartile, 27.8%] vs 2.8% [first quartile, 2.3%; third quartile, 4.9%]; P < .001). NSIP participants also had a reduced ratio of RBC-to-barrier peaks (median, 0.24 [first quartile, 0.19; third quartile, 0.31] vs 0.57 [first quartile, 0.52; third quartile, 0.67]; P < .001) and a reduced RBC chemical shift (median, 217.5 ppm [first quartile, 217.0 ppm; third quartile, 218.0 ppm] vs 218.2 ppm [first quartile, 217.9 ppm; third quartile, 218.6 ppm]; P = .001). Conclusion Participants with nonspecific interstitial pneumonia had increased barrier uptake and decreased red blood cell (RBC) transfer compared with healthy controls measured using xenon 129 gas-exchange MRI and reduced RBC-to-barrier ratio and RBC chemical shift measured using spectroscopy. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Wild in this issue.


Assuntos
Doenças Pulmonares Intersticiais/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Troca Gasosa Pulmonar , Isótopos de Xenônio , Adulto , Estudos Transversais , Feminino , Humanos , Pulmão/diagnóstico por imagem , Pulmão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Análise Espectral/métodos
15.
Tissue Barriers ; 9(4): 1937013, 2021 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-34232823

RESUMO

Blood-gas barrier (BGB) or alveolar-capillary barrier is the primary tissue barrier affected by coronavirus disease 2019 (COVID-19). Comprising alveolar epithelial cells (AECs), endothelial cells (ECs) and the extracellular matrix (ECM) in between, the BGB is damaged following the action of multiple pro-inflammatory cytokines during acute inflammation. The infection of AECs and ECs with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen behind COVID-19, triggers an inflammatory response at the BGB, inducing the release of interleukin 1 (IL-1), IL-6, tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-ß), high mobility group box 1 (HMGB1), matrix metalloproteinases (MMPs), intercellular adhesion molecule-1 (ICAM-1) and platelet activating factor (PAF). The end result is the disassembly of adherens junctions (AJs) and tight junctions (TJs) in both AECs and ECs, AEC hyperplasia, EC pyroptosis, ECM remodeling and deposition of fibrin clots in the alveolar capillaries, leading to disintegration and thickening of the BGB, and ultimately, hypoxia. This commentary seeks to provide a brief account of how the BGB might become affected in COVID-19.


Assuntos
Barreira Alveolocapilar/metabolismo , COVID-19/metabolismo , Troca Gasosa Pulmonar , Células Epiteliais Alveolares/metabolismo , Células Epiteliais Alveolares/patologia , Barreira Alveolocapilar/patologia , COVID-19/patologia , Humanos , Microvasos/metabolismo , Microvasos/patologia
16.
J Appl Physiol (1985) ; 131(3): 1009-1019, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34292790

RESUMO

The O2 uptake (V̇o2) data at the onset of an exercise are usually fitted with a mono-exponential function, after removal of the data pertaining to a conventional initial time period (ΔTr) lasting ∼20 s. We performed a thorough quantitative analysis on the effects of removing data pertaining to different ΔTr, aiming at identifying an objective method to establish the appropriate ΔTr. Breath-by-breath O2 uptake responses, acquired from 25 healthy adults performing a step moderate-intensity exercise, and 104 simulated biexponential responses, were analyzed. For all the responses, the kinetic parameters of a mono-exponential function and the corresponding asymptotic standard errors (ASEs) were estimated by nonlinear regression, removing the data pertaining to progressively longer initial periods (1 s each) up to 60 s. Four methods to establish objectively ΔTr were compared. The minimum estimated τ was obtained for ΔTr ≅ 35 s in both the V̇o2 and simulated data, that was about 30% lower compared with that obtained for ΔTr ≅ 0s. The average ASE values remained quite constant up to ΔTr ≅ 35 s, thereafter they increased remarkably. The τ used to generate the simulated response fell within the confidence intervals of the estimated τ in ∼85% of cases for ΔTr = 20 s ("20 s-w" method); this percentage increased to ∼92% of cases when ΔTr was established according to both the minimum τ and its narrowest confidence interval ("Mixed" method). In conclusion, the effects of removing V̇o2 data pertaining to different ΔTr are remarkable. The "Mixed" method provided estimated parameters close to those used to generate the simulated responses and is thus endorsed.NEW & NOTEWORTHY We propose a method to objectively establish the initial time period to be removed from the fitting window when, using a mono-exponential model, the kinetics of the fundamental component is determined on breath-by-breath O2 uptake data collected at the onset of a moderate-intensity exercise. Innovative statistical parameters ("Coverage" and "Concordance5%," applicable on simulated responses) were used to compare its performance with that of other three methods. The proposed method yielded the best "Coverage" and "Concordance5%."


Assuntos
Exercício Físico , Consumo de Oxigênio , Adulto , Teste de Esforço , Humanos , Cinética , Troca Gasosa Pulmonar
17.
PLoS One ; 16(7): e0255005, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34320018

RESUMO

BACKGROUND: Pulmonary complications such as pneumonia, pulmonary atelectasis, and subsequent respiratory failure leading to ventilatory support are a common occurrence in critically ill patients. Intrapulmonary percussive ventilation (IPV) is used to improve gas exchange and promote airway clearance in these patients. The current evidence regarding the effectiveness of intrapulmonary percussive ventilation in critical care settings remains unclear. This systematic review aims to summarise the evidence of the effectiveness of intrapulmonary percussive ventilation on intensive care unit length of stay (ICU-LOS) and respiratory outcomes in critically ill patients. RESEARCH QUESTION: In critically ill patients, is intrapulmonary percussive ventilation effective in improving respiratory outcomes and reducing intensive care unit length of stay. METHODS: A systematic search of intrapulmonary percussive ventilation in intensive care unit (ICU) was performed on five databases from 1979 to 2021. Studies were considered for inclusion if they evaluated the effectiveness of IPV in patients aged ≥16 years receiving invasive or non-invasive ventilation or breathing spontaneously in critical care or high dependency units. Study titles and abstracts were screened, followed by data extraction by a full-text review. Due to a small number of studies and observed heterogeneities in the study methodology and patient population, a meta-analysis could not be included in this review. Outcomes of interest were summarised narratively. RESULTS: Out of 306 identified abstracts, seven studies (630 patients) met the eligibility criteria. Results of the included studies provide weak evidence to support the effectiveness of intrapulmonary percussive ventilation in reducing ICU-LOS, improving gas exchange, and reducing respiratory rate. INTERPRETATION: Based on the findings of this review, the evidence to support the role of IPV in reducing ICU-LOS, improving gas exchange, and reducing respiratory rate is weak. The therapeutic value of IPV in airway clearance, preventing pneumonia, and treating pulmonary atelectasis requires further investigation.


Assuntos
Estado Terminal/terapia , Pneumonia/epidemiologia , Troca Gasosa Pulmonar , Respiração Artificial , Bases de Dados Factuais , Humanos , Unidades de Terapia Intensiva , Tempo de Internação , Pneumonia/patologia , Respiração Artificial/efeitos adversos , Taxa Respiratória , Resultado do Tratamento
18.
Crit Care ; 25(1): 248, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-34266454

RESUMO

BACKGROUND: Differences in physiology of ARDS have been described between COVID-19 and non-COVID-19 patients. This study aimed to compare initial values and longitudinal changes in respiratory system compliance (CRS), oxygenation parameters and ventilatory ratio (VR) in patients with COVID-19 and non-COVID-19 pulmonary ARDS matched on oxygenation. METHODS: 135 patients with COVID-19 ARDS from two centers were included in a physiological study; 767 non-COVID-19 ARDS from a clinical trial were used for the purpose of at least 1:2 matching. A propensity-matching was based on age, severity score, oxygenation, positive end-expiratory pressure (PEEP) and pulmonary cause of ARDS and allowed to include 112 COVID-19 and 198 non-COVID pulmonary ARDS. RESULTS: The two groups were similar on initial oxygenation. COVID-19 patients had a higher body mass index, higher CRS at day 1 (median [IQR], 35 [28-44] vs 32 [26-38] ml cmH2O-1, p = 0.037). At day 1, CRS was correlated with oxygenation only in non-COVID-19 patients; 61.6% and 68.2% of COVID-19 and non-COVID-19 pulmonary ARDS were still ventilated at day 7 (p = 0.241). Oxygenation became lower in COVID-19 than in non-COVID-19 patients at days 3 and 7, while CRS became similar. VR was lower at day 1 in COVID-19 than in non-COVID-19 patients but increased from day 1 to 7 only in COVID-19 patients. VR was higher at days 1, 3 and 7 in the COVID-19 patients ventilated using heat and moisture exchangers compared to heated humidifiers. After adjustment on PaO2/FiO2, PEEP and humidification device, CRS and VR were found not different between COVID-19 and non-COVID-19 patients at day 7. Day-28 mortality did not differ between COVID-19 and non-COVID-19 patients (25.9% and 23.7%, respectively, p = 0.666). CONCLUSIONS: For a similar initial oxygenation, COVID-19 ARDS initially differs from classical ARDS by a higher CRS, dissociated from oxygenation. CRS become similar for patients remaining on mechanical ventilation during the first week of evolution, but oxygenation becomes lower in COVID-19 patients. TRIAL REGISTRATION: clinicaltrials.gov NCT04385004.


Assuntos
COVID-19/terapia , Respiração com Pressão Positiva/métodos , Síndrome do Desconforto Respiratório/terapia , Idoso , Gasometria , Índice de Massa Corporal , COVID-19/fisiopatologia , Feminino , Humanos , Unidades de Terapia Intensiva , Masculino , Pessoa de Meia-Idade , Pontuação de Propensão , Troca Gasosa Pulmonar/fisiologia , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório/fisiopatologia , Testes de Função Respiratória , Mecânica Respiratória/fisiologia , SARS-CoV-2
19.
Eur Respir Rev ; 30(161)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34289982

RESUMO

Ventilatory efficiency can be evaluated using the relationship between minute ventilation (V'E) and the rate of CO2 production (V'CO2 ). In accordance with the modified alveolar ventilation equation, this relationship is determined by changes in dead space volume (V D) and/or the arterial CO2 tension (P aCO2 ) equilibrium point. In this review, we summarise the physiological factors that may account for normative ageing and pregnancy induced increases in V'E/V'CO2 during exercise. Evidence suggests that age-related increases in V D and pregnancy-related decreases in the P aCO2 equilibrium point are mechanistically linked to the increased V'E/V'CO2 during exercise. Importantly, the resultant increase in V'E/V'CO2 (ratio or slope), with normal ageing or pregnancy, remains below the critical threshold for prognostic indication in cardiopulmonary disease, is not associated with increased risk of adverse health outcomes, and does not affect the respiratory system's ability to fulfil its primary role of eliminating CO2 and maintaining arterial oxygen saturation during exercise.


Assuntos
Dióxido de Carbono , Teste de Esforço , Envelhecimento , Exercício Físico , Feminino , Humanos , Gravidez , Troca Gasosa Pulmonar
20.
Med Sci Sports Exerc ; 53(8): 1606-1614, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34261991

RESUMO

INTRODUCTION: The mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown. METHODS: In twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min-1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout. RESULTS: Baseline Piso was not different among RI rates (analysis of variance; P > 0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P < 0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P > 0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P < 0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P < 0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P > 0.05), thus there was no "power reserve." In RI-10, Piso was greater than RI peak power at intolerance (P < 0.001), that is, there was a "power reserve." CONCLUSIONS: In RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.


Assuntos
Exercício Físico , Fadiga Muscular , Consumo de Oxigênio , Adulto , Teste de Esforço , Tolerância ao Exercício , Feminino , Humanos , Masculino , Músculo Esquelético/fisiologia , Troca Gasosa Pulmonar , Adulto Jovem
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