Preemptive hemodynamic intervention restricting the administration of fluids attenuates lung edema progression in oleic acid-induced lung injury.

OBJECTIVE: A study is made of the influence of preemptive hemodynamic intervention restricting fluid administration upon the development of oleic acid-induced lung injury. DESIGN: A randomized in vivo study in rabbits was carried out. SETTING: University research laboratory. SUBJECTS: Sixteen anesthetized, mechanically ventilated rabbits. VARIABLES: Hemodynamic measurements obtained by transesophageal Doppler signal. Respiratory mechanics computed by a least square fitting method. Lung edema assessed by the ratio of wet weight to dry weight of the right lung. Histological examination of the left lung. INTERVENTIONS: Animals were randomly assigned to either the early protective lung strategy (EPLS) (n=8) or the early protective hemodynamic strategy (EPHS) (n=8). In both groups, lung injury was induced by the intravenous infusion of oleic acid (OA) (0.133mlkg-1h-1 for 2h). At the same time, the EPLS group received 15mlkg-1h-1 of Ringer lactate solution, while the EPHS group received 30mlkg-1h-1. Measurements were obtained at baseline and 1 and 2h after starting OA infusion. RESULTS: After 2h, the cardiac index decreased in the EPLS group (p<0.05), whereas in the EPHS group it remained unchanged. Lung compliance decreased significantly only in the EPHS group (p<0.05). Lung edema was greater in the EPHS group (p<0.05). Histological damage proved similar in both groups (p=0.4). CONCLUSIONS: In this experimental model of early lung injury, lung edema progression was attenuated by preemptively restricting the administration of fluids.

[Monitorization of respiratory mechanics in the ventilated patient]. / Monitorización de la mecánica respiratoria en el paciente ventilado.

Monitoring during mechanical ventilation allows the measurement of different parameters of respiratory mechanics. Accurate interpretation of these data can be useful for characterizing the situation of the different components of the respiratory system, and for guiding ventilator settings. In this review, we describe the basic concepts of respiratory mechanics, their interpretation, and their potential use in fine-tuning mechanical ventilation.

Mean airway pressure as a parameter of lung-protective and heart-protective ventilation.

Mean airway pressure (MAP) is the mean pressure generated in the airway during a single breath (inspiration + expiration), and is displayed on most anaesthesia and intensive care ventilators. This parameter, however, is not usually monitored during mechanical ventilation because it is poorly understood and usually only used in research. One of the main determinants of MAP is PEEP. This is because in respiratory cycles with an I:E ratio of 1:2, expiration is twice as long as inspiration. Although MAP can be used as a surrogate for mean alveolar pressure, these parameters differ considerably in some situations. Recently, MAP has been shown to be a useful prognostic factor for respiratory morbidity and mortality in mechanically ventilated patients of various ages. Low MAP has been associated with a lower incidence of 90-day mortality, shorter ICU stay, and shorter mechanical ventilation time. MAP also affects haemodynamics: there is evidence of a causal relationship between high MAP and low perfusion index, both of which are associated with poor prognosis in mechanically ventilated patients. Elevated MAP values have also been associated with high central venous pressure and lactate, which are indicative of ventilator-associated right ventricular failure and tissue hypoperfusion, respectively. MAP, therefore, is an important parameter to measure in clinical practice. The aim of this review has been to identify the determinants of MAP, the pros and cons of using MAP instead of traditional protective ventilation parameters, and the evidence that supports the use of MAP in clinical practice.

Influence of mild pulmonary congestion on diaphragmatic mobility and activities of daily living in chronic kidney disease: An experimental and clinical study.

BACKGROUND: Pulmonary congestion is a strong predictor of mortality and cardiovascular events in chronic kidney disease (CKD); however, the effects of the mild form on functionality have not yet been investigated. The objective of this study was to assess the influence of mild pulmonary congestion on diaphragmatic mobility (DM) and activities of daily living (ADL) in hemodialysis (HD) subjects, as well as compare ADL behavior on dialysis and non-dialysis days. In parallel, experimentally induce CKD in mice and analyze the resulting pulmonary and functional repercussions. METHODS: Thirty subjects in HD underwent thoracic and abdominal ultrasonography, anthropometric assessment, lung and kidney function, respiratory muscle strength assessment and symptoms analysis. To measure ADL a triaxial accelerometer was used over seven consecutive days. Twenty male mice were randomized in Control and CKD group. Thoracic ultrasonography, TNF-α analysis in kidney and lung tissue, exploratory behavior and functionality assessments were performed. RESULTS: Mild pulmonary congestion caused a 26.1% decline in DM (R2=.261; P=.004) and 20% reduction in walking time (R2=.200; P=.01), indicating decreases of 2.23mm and 1.54min, respectively, for every unit increase in lung comet-tails. Regarding ADL, subjects exhibited statistically significant differences for standing (P=.002), walking (P=.034) and active time (P=.002), and number of steps taken (P=.01) on days with and without HD. In the experimental model, CKD resulted in increased levels of TNF-α on kidneys (P=.037) and lungs (P=.02), attenuation of exploratory behavior (P=.01) and significant decrease in traveled distance (P=.034). Thoracic ultrasonography of CKD mice showed presence of B-lines. CONCLUSION: The mild pulmonary congestion reduced DM and walking time in subjects undergoing HD. Individuals were less active on dialysis days. Furthermore, the experimental model implies that the presence of pulmonary congestion and inflammation may play a decisive role in the low physical and exploratory performance of CKD mice.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study.

INTRODUCTION: Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise. OBJECTIVE: To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects. METHODS: Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons. RESULTS: Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40). CONCLUSION: The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

[Effects of high frequency chest wall oscillatory (HFCWO) therapy on gas exchange and ventilation in healthy participants]. / Efectos en población sana de la terapia con oscilación de alta frecuencia sobre la pared torácica (HFCWO) a nivel de la dinámica de gases pulmonares y de la mecánica respiratoria.

INTRODUCTION: Chest physiotherapy is an essential part of the treatment of respiratory diseases with increased respiratory secretion and ineffective cough. To date, there have been no studies on the effect of high frequency chest wall oscillatory (HFCWO) therapy on respiratory muscle strength, ventilation and gas exchange. The aim of this study was therefore to assess these three factors in healthy participants. METHODS: Respiratory muscle strength was measured before and immediately after HFCWO therapy in 25 healthy participants. During the treatment, we continuously measured ventilation parameters, gas exchange, oxygen saturation and heart rate. All participants underwent HFCWO sessions twice (with 24hours difference) with the same procedure. Symptoms during the session and discomfort were measured with the visual analog scale (VAS). RESULTS: HFCWO therapy produced a change in breathing pattern with increased ventilation associated with altered gas exchange. Heart rate also increased, with no changes in oxygenation. There was no effect, either beneficial or deleterious, on the strength of respiratory muscles. Up to 20% of participants reported substantial discomfort (VAS≥5/10) during the session. CONCLUSIONS: This study shows that, during the application of HFCWO therapy in healthy participants, ventilation and heart rate increased. However, there were undesirable effects on gas exchange with a high degree of intolerance among volunteers, with no effects on respiratory muscle strength.

[Impact of Grade I obesity on respiratory mechanics during video laparoscopic surgery: prospective longitudinal study]. / Impacto da obesidade Grau I na mecânica respiratória durante cirurgia videolaparoscópica: estudo longitudinal prospectivo.

INTRODUCTION AND OBJECTIVES: The association pneumoperitoneum and obesity in video laparoscopy can contribute to pulmonary complications, but has not been well defined in specific groups of obese individuals. We assessed the effects of pneumoperitoneum in respiratory mechanics in Grade I obese compared to non-obese. METHODS: Prospective study including 20 patients submitted to video laparoscopic cholecystectomy, normal spirometry, divided into non-obese (BMI ≤ 25kg.m-2) and obese (BMI > 30kg.mg-2), excluding Grade II and III obese. We measured pulmonary ventilation mechanics data before pneumoperitoneum (baseline), and five, fifteen and thirty minutes after peritoneal insufflation, and fifteen minutes after disinflation (final). RESULTS: Mean BMI of non-obese was 22.72 ± 1.43kg.m-2 and of the obese 31.78 ± 1.09kg.m-2, p < 0.01. Duration of anesthesia and of peritoneal insufflation was similar between groups. Baseline pulmonary compliance (Crs) of the obese (38.3 ± 8.3mL.cm H2O-1) was lower than of the non-obese (47.4 ± 5.7mL.cm H2O-1), p = 0.01. After insufflation, Crs decreased in both groups and remained even lower in the obese at all moments assessed (GLM p < 0.01). Respiratory system peak pressure and plateau pressure were higher in the obese, albeit variations were similar at moments analyzed (GLM p > 0.05). The same occurred with elastic pressure, higher in the obese at all times (GLM p = 0.04), and resistive pressure showed differences in variations between groups during pneumoperitoneum (GLM p = 0,05). CONCLUSIONS: Grade I obese presented more changes in pulmonary mechanics than the non-obese during video laparoscopies and the fact requires mechanical ventilation-related care.

Effects on Humidification and Ventilatory Parameters of Three Single-limb Heated-wired Circuits for Non-invasive Ventilation: A Bench Study.

BACKGROUND: The objective of this study was to evaluate the effects of three single-limb heated wired circuits (SLHWC) for NIV, on ventilatory parameters and humidification performance in a simulation lung model. METHODS: Three SLHWC compatible with the MR-850 Heated Humidifier (HH) (Fisher & Paykel, Auckland, New Zealand) were tested: RT-319 (FP) (Fisher & Paykel, Auckland, New Zealand), Respironics 1045770 (RP) (DEAS, Castel Bolognese, Italy) and Intersurgical B/SYS 5809001 (IT) (Intersurgical, Wokingham, UK). A Bipap Vision ventilator (Philips Respironics, Murrysville, PA, USA) in pressure control ventilation (PCV) connected to a test lung was used for simulation. Each SHWC performance was evaluated in four ventilatory conditions: IPAP of 15cmH2O with FiO2 0.3 and 1, respectively; and, IPAP of 25cmH2O with FiO2 0.3 and 1, respectively. EPAP was set at 5cmH2O. Hygrometric and ventilatory measurements including: relative humidity (RH), temperature (T), Pplat, PIP, PEEP, peak inspiratory flow (PIF), and tidal volume (Vt) were measured. RESULTS: In each FiO2 group absolute humidity (AH) was similar with FP regardless of the IPAP level employed compared to IT and RP (P<.001). Except for RP at FiO2 0.3, AH increased significantly in IT and RP groups as IPAP increased (P<.001). PIP, Pplat, PEEP, PIF, and Vt values were significantly higher with FP and RP in each FiO2 group compared to IT (P<.001). CONCLUSIONS: Humidification performance varied significantly among the three circuits, being FP the only one able to maintain stable AH values during the study with no influence on ventilatory parameters.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study.

INTRODUCTION: Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise. OBJECTIVE: To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects. METHODS: Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons. RESULTS: Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40). CONCLUSION: The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

Conventional monitoring is not sufficient to assess respiratory effort during assisted ventilation. / La monitorización convencional no es suficiente para valorar el esfuerzo respiratorio durante la ventilación asistida.

OBJECTIVE: Study the relationship and concordance between calculated respiratory effort using the signals of the ventilator (Pmus) and that measured in esophageal pressure (Pes) on mechanical ventilation with different levels of respiratory assistance. DESIGN: Prospective cohort study. AMBIT: Intensive Care Unit of 2 universitary hospitals. Patients Patients on weaning time. PROCEDURE: Airway, esophageal and respiratory flow were recorded on CPAP, assist volume control (ACV) and pressure support (PS), with complete (ACV1,PS1) and partial assistance (ACV5,PS5). MEASUREMENT: respiratory variations of Pes and Pmus (Δ: cmH2O) and pressure time product (PTPm: cmH2O·s/m). RESULTS: Fourty one records were studied, the assistance was in CPAP of 5cmH2O, PS1 of 15±5 reduced to 9±4cmH2O. In ACV1 the inspiratory flow was 1±0.2l/s, reduced to 0.49±0.1l/s for ACV5. The increase in respiratory assistance decreases respiratory effort, measured in Delta Pes (CPAP, ACV5, ACV1, PS5, PS1): 11±3, 6±3, 5±3, 9±6, 7±7 and in Pmus 16±5, 10±6, 5±3, 10±6, 5±4cmH2O (P<.001). The PTP per minute measured in Pes: 213±87, 96±91, 23±24, 206±121, 108±100 (P=.001) and in Pmus: 293±117, 156±84, 24±32, 233±121, 79±90 (P<.001). The measurements in Pes and Pmus showed the following correlation, in Delta: 0.72 and PTPm, 0.87. The Bland-Altman analysis indicates that the difference between Delta Pes-Pmus can be 16 and the PTPm of 264 and the systematic error in Delta: -0.98±4.4 and PTPm -23.69±66.3cmH2O·s/m. CONCLUSIONS: Calculated and measured parameters of respiratory effort showed unacceptable differences in clinical practice.

Real-time changes in rib cage expansion and use of abdominal mechanical stimulation in newborns: a quasi-experimental study / Mudanças na expansibilidade torácica com o uso de estímulo mecânico na região abdominal em recém-nascidos: um estudo quase-experimental

ABSTRACT Objective: To assess the rib cage expansion and respiratory rate in newborns using an abdominal stabilization band. Methods: The study included 32 newborns of both genders, with gestational age between 35 and 41 weeks. The abdominal stabilization band was used for 15 minutes between the xiphoid process and the anterosuperior iliac crest, with an abdominal contention 0.5cm smaller than the abdominal circumference. The rib cage expansion was evaluated by a breathing transducer (Pneumotrace II™) three minutes before using the band, during the use (15 minutes), and ten minutes after removing the band. The Shapiro-Wilk test verified data normality, and the Wilcoxon test compared the variables considering rib cage expansion and respiratory rate. Significance was set to p<0.05. Results: There was an increase in respiratory rate when comparing before and ten minutes after removing (p=0.008) the abdominal stabilization band, as well as when comparing during its use and ten minutes after its removal (p=0.001). There was also an increase in rib cage expansion when comparing before and during the use of the abdominal stabilization band (p=0.005). Conclusions: The use of the abdominal stabilization band promoted an increase in the rib cage expansion and respiratory rate in the assessed newborns and may be a viable option to improve the respiratory kinematics of this population.

RESUMO Objetivo: Avaliar a expansibilidade torácica e a frequência respiratória em recém-nascidos que fizeram uso de uma faixa de estabilização abdominal. Métodos: O estudo incluiu 32 recém-nascidos de ambos os sexos, com idade gestacional entre 35 e 41 semanas. A faixa de estabilização abdominal foi mantida por 15 minutos entre o processo xifoide e a espinha ilíaca anterossuperior, com contenção abdominal 0,5 cm menor do que a circunferência abdominal. A expansibilidade torácica foi avaliada por um transdutor piezoelétrico (Pneumotrace II™) 3 minutos antes do uso da faixa, durante 15 minutos, e 10 minutos após sua retirada. A normalidade das variáveis foi testada pelo teste de Shapiro-Wilk e a análise comparativa da expansibilidade torácica e da frequência respiratória foi realizada por meio do teste t pareado, considerando-se p<0,05. Resultados: Houve aumento da frequência respiratória quando comparados os tempos antes do uso da faixa e 10 minutos após a retirada (p=0,008), bem como quando comparados os tempos durante o uso e 10 minutos após a retirada da faixa (p=0,001). Houve aumento da expansibilidade torácica quando comparados os tempos antes e durante o uso da faixa (p=0,005). Conclusões: O uso da faixa de estabilização abdominal conferiu aumento da expansibilidade torácica e da frequência respiratória nos recém-nascidos estudados, podendo ser uma opção viável para a melhora da cinemática respiratória dessa população.

Bronchodilator response assessment through impulse oscillometry system and spirometry in children and adolescents with cystic fibrosis / Avaliação da resposta broncodilatadora por meio do sistema de oscilometria de impulso e espirometria em crianças e adolescentes com fibrose cística

ABSTRACT Objective: To investigate the effect of bronchodilator on the respiratory mechanics and pulmonary function of children and adolescents with cystic fibrosis. Methods: Cross-sectional study on clinically stable children and adolescents with cystic fibrosis aged from six to 15 years. Participants underwent impulse oscillometry and spirometry evaluations before and 15 minutes after bronchodilator inhalation. The Kolmogorov-Smirnov test was applied to verify the sample distribution, and the Student's t-test and Wilcoxon test were used to compare the data before and after bronchodilator inhalation. Results: The study included 54 individuals with a mean age of 9.7±2.8 years. The analysis showed a statistically significant improvement in impulse oscillometry and spirometry parameters after bronchodilator inhalation. However, according to the American Thoracic Society (ATS) and European Respiratory Society (ERS) recommendations (2020 and 2021), this improvement was not sufficient to classify it as a bronchodilator response. Conclusions: The use of bronchodilator medication improved respiratory mechanics and pulmonary function parameters of children and adolescents with cystic fibrosis; however, most patients did not show bronchodilator response according to ATS/ERS recommendations.

RESUMO Objetivo: Investigar o efeito do broncodilatador na mecânica respiratória e função pulmonar de crianças e adolescentes com fibrose cística. Métodos: Estudo transversal em crianças e adolescentes com fibrose cística clinicamente estáveis, com idade entre seis e 15 anos. Os participantes realizaram avaliações por meio do sistema de oscilometria de impulso e espirometria antes e 15 minutos depois da inalação de broncodilatador. Foi aplicado o teste Kolmogorov-Smirnov para verificar a distribuição da amostra. Para comparar os dados antes e depois do broncodilatador foram utilizados os testes t de Student e Wilcoxon. Resultados: Participaram do estudo 54 indivíduos com média de idade de 9,7±2,8 anos. Houve melhora estatisticamente significativa nos parâmetros do oscilometria de impulso e espirometria após a inalação com broncodilatador. No entanto, de acordo com recomendações da American Thoracic Society (ATS) e European Respiratory Society (ERS) (2020 and 2021), essa melhora não foi suficiente para classificar como reposta broncodilatadora. Conclusões: O uso de medicamento broncodilatador melhorou a mecânica respiratória e função pulmonar de crianças e adolescentes com fibrose cística, no entanto a maioria da amostra não apresentou resposta ao broncodilatador de acordo com as recomendações da ATS/ERS.

[Comparison of volume-controlled and pressure-controlled ventilation on respiratory mechanics in laparoscopic bariatric surgery: randomized clinical trial]. / Comparação das ventilações controlada por volume e controlada por pressão na mecânica respiratória em cirurgia bariátrica laparoscópica: estudo clínico randômico.

BACKGROUND: It is not clear which mechanical ventilation mode should be used in bariatric surgery, one of the treatment options for patients with obesity. OBJECTIVES: To compare volume-controlled ventilation and pressure-controlled ventilation in terms of respiratory mechanics and arterial blood gas values in patients undergoing laparoscopic bariatric surgery. METHODS: Sixty-two patients with morbid obesity scheduled for gastric bypass were included in this study. Their ideal body weights were calculated during preoperative visits, and patients were divided into two groups, volume-controlled ventilation and pressure-controlled ventilation. The patients were ventilated in accordance with a previously determined algorithm. Mechanical ventilation parameters and arterial blood gas analysis were recorded 5 minutes after induction, 30 minutes after pneumoperitoneum, and at the end of surgery. Also, the dynamic compliance, inspired O2 pressure/fractional O2 ratio, and alveolar-arterial oxygen gradient pressure were calculated. RESULTS: Peak airway pressures were lower in patients ventilated in pressure-controlled ventilation mode at the end of surgery (p = 0.011). Otherwise, there was no difference between groups in terms of intraoperative respiratory parameters and arterial blood gas analyses. CONCLUSIONS: Pressure-controlled ventilation mode is not superior to volume-controlled ventilation mode in patients with laparoscopic bariatric surgery.

Cambios en Mecánica Respiratoria en Usuarios Pediátricos en Ventilación Mecánica Post Cirugía de Cardiopatía Congénita Sometidos a Kinesiología Respiratoria versus Succión Endotraqueal. Revisión Estructurada / Changes in Respiratory Mechanics in Pediatric Users on Mechanical Ventilation Post Congenital Heart Disease Surgery Undergoing Respiratory Kinesiology versus Endotracheal Suction. Structured Review

Introducción. Las cardiopatías congénitas (CC) en Chile corresponden a la segunda causa de muerte en menores de 1 año, requiriendo cirugías paliativas y/o correctivas el 65% de estas. En el post operatorio frecuentemente se utiliza ventilación mecánica invasiva (VM) y succión endotraqueal (SET) para remover secreciones. Sin embargo, la kinesiología respiratoria (KTR) ha mostrado mejoras significativas en la distensibilidad toracopulmonar (Cest) y resistencia de vía aérea (Rva) en otros grupos de usuarios pediátricos y adultos en VM. Objetivo. Comparar los cambios en la Cest y Rva en usuarios pediátricos en VM post cirugía de cardiopatía congénita (CCC) sometidos a KTR versus SET exclusiva. Métodos. Revisión sistemática de estudios publicados en bases de datos PUBMED, PeDro, Scielo y Google Scholar que comparan el uso de KTR ó SET sobre los cambios en mecánica ventilatoria en usuarios pediátricos en VM post cirugía de cardiopatía congénita, limitados a inglés, español y portugués, excluyendo a sujetos con traqueostomía o con oxigenación por membrana extracorpórea. Se utilizó guía PRISMA para la selección de artículos. Se revisaron 397 artículos y se seleccionó 1 artículo extra de los artículos sugeridos. Se eliminó 1 artículo por duplicidad. Por títulos y resúmenes se seleccionaron 2 artículos, los cuales al leer el texto completo fueron retirados debido a que la población no correspondía a cardiópatas. Resultados. El final de artículos seleccionados fue de 0 artículos, debido a lo cual se removió el operador Booleano "NOT", y se removió la población de cardiopatías. De este modo quedaron 2 artículos seleccionados para la revisión cualitativa final donde se compara KTR versus SET, y KTR en kinesiólogos especialistas y no especialistas, mostrando ambos aumento en la Cest y disminución de la Rva a favor de la KTR, hasta los 30 minutos post intervención. Conclusiones. No se encontraron artículos que demuestren cambios en Cest y Rva con el uso de KTR + SET versus SET exclusiva, en usuarios pediátricos ventilados posterior a CCC. Con la remoción de filtros seleccionamos 2 artículos que demuestran aumento de Cest y disminución de Rva en sujetos pediátricos en VM, uno comparando con SET, y por grupos de especialistas y no especialistas en respiratorio. Se sugieren estudios primarios para evaluar los efectos de esta intervención en esta población.

Introduction. Congenital heart diseases (CHD) are the second general cause for children death under 1 year. In Chile, approximately 65% CHD need surgery, could was palliative or corrective. In the postoperative period, invasive mechanical ventilation (MV) is frequently used as a life support method, but it is associated with complications. Tracheal suction (SET) is regularly used to remove secretions; however, respiratory chest physiotherapy (KTR) has shown significant improvements in thoraco-pulmonary compliance and airway resistance in other groups of pediatrics and adult's users in MV. Objetive. to compare changes in thoraco-pulmonary compliance and airway resistance in pediatric subjects under mechanical ventilation after congenital heart disease surgery comparing chest physiotherapy and exclusive tracheal suction. Methods. systematic review of studies published in PUBMED, PeDro, Scielo and Google Scholar databases who compares KTR or SET use on changes in ventilatory mechanics in pediatric users under MV after congenital heart disease surgery, limited to English, Spanish and Portuguese languages, excluding user with tracheostomy or extracorporeal membrane of oxygenation. It was use the PRISMA guide to articles selection. A search was carried out, with a total of 397 articles reviewed (English: PubMed = 3, PeDro = 8, Scholar = 383; Spanish: Scholar = 3, Scielo = 0; and Portuguese: Scielo = 0). One extra article was selected from the suggested articles, and 1 article was eliminated due to duplication. By titles and abstracts, 2 articles were selected, but the population did not correspond to heart disease. Results. the final selected articles were 0 articles. By this reason, it were removed: Boolean operator "NOT", and congenital heart disease population. Thus, 2 articles were selected for the final qualitative review where it was compares KTR versus SET, and KTR by specialist and non-specialist. Both articles shown improvement in compliance and resistance until 30 minutes post intervention. The CC population was in a 40 to 60% range in both studies. Conclusions. it was no found articles that demonstrate changes in compliance and resistance in the airway with the use of KTR + SET versus exclusive SET in pediatric users after CCC connected to MV. After filter remotion, we found 2 studies shown improves in increase compliance and reduce resistance in pediatric user in MV, ones comparing with SET, and the other one comparing between specialists in respiratory pediatric physiotherapy and not specialists. It suggests to made primary clinical studies about this intervention in CC population.

Fisiología respiratoria: fisiopatología de las enfermedades obstructivas / Pathophysiology of obstructive diseases

Las enfermedades obstructivas de la vía aérea pediátrica son muy frecuentes debido a los fenómenos mecánicos que están involucrados. En los niños más pequeños, la marcada resistencia de las vías aéreas pequeñas, determinada por la falta de tejido elástico y una caja torácica aún no bien desarrollada; tanto su estructura como la musculatura, facilitarán que cuadros infecciosos, mecánicos (cuerpo extraño) y compresivos, determinen que los flujos de aire se vean limitados y con ello la ventilación alveolar. La respuesta fisiológica con aumento del trabajo respiratorio es limitada y por lo tanto la fatiga muscular determinará hipoventilación con las consecuencias de hipoxemia e hipercapnia.

Obstructive diseases of the pediatric airway are very frequent due to the mechanical phenomena that are involved. The marked resistance of the small airways, such as the lack of elastic tissue and a thoracic cage that is not yet well developed, both in its structure and in the musculature, will make it easier for infectious, mechanical (foreign body), compressive and other conditions to determine that the flows of air are limited and with it the alveolar ventilation. The physiological response with increased work of breathing is limited and therefore muscle fatigue will determine hypoventilation, with the consequences of hypoxemia and hypercapnia.

Series en disnea. Parte 2. Análisis de sus mecanismos según pasan los años / Series on dyspnea. Part 2. Analysis of its mechanisms as the years go by

RESUMEN Este artículo está dedicado al análisis detallado de los mecanismos de disnea. Se tra tarán el control químico de la respiración, los reflejos neurales, la mecánica respiratoria, el costo de oxígeno para respirar y la inadecuación entre tensión y longitud de la fibra muscular. En general, las diferentes explicaciones estuvieron asociadas al desarrollo de aparatos y metodologías de estudio de los laboratorios pulmonares. Todas las teorías tuvieron defensores y detractores e, interesantemente, con el desarrollo de sofisticadas técnicas neurofisiológicas y de imágenes funcionales ha sido posible jerarquizar cada uno de los mecanismos. Todas han sobrevivido al paso del tiempo y ninguna puede explicar de manera unicista la disnea en todas las situaciones clínicas, lo cual habla de la naturaleza compleja y multifactorial del fenómeno.

ABSTRACT This article is devoted to a detailed analysis of the mechanisms of dyspnea. Chemical control of respiration, neural reflexes, respiratory mechanics, the cost of oxygen to breathe, and the mismatch between tension and muscle fiber length will be discussed. In general, the different explanations were associated with the development of apparatus and study methodologies in pulmonary laboratories. All the theories had defenders and detractors and, interestingly, with the development of sophisticated neurophysiological techniques and functional imaging it has been possible to prioritize each of the mecha nisms. All have survived the passage of time and none can explain dyspnea in all clinical situations, which speaks of the complex and multifactorial nature of the phenomenon.

Series en disnea. Parte 3. Mecanismos, copia eferente o descarga corolaria / Series on Dyspnea. Part 3. Mechanisms, efferent copy or corollary discharge

Todas las teorías sobre los mecanismos de generación de disnea tuvieron defensores y detractores e, interesantemente, con el desarrollo de sofisticadas técnicas neurofisiológicas y de imágenes funcionales ha sido posible jerarquizar cada uno de ellos. Todas han sobrevivido al paso del tiempo y ninguna puede explicar por sí sola la disnea en todas las situaciones clínicas, lo cual habla de la naturaleza compleja y multifactorial del fenómeno. El concepto de inadecuación tensión y longitud halló en las últimas décadas un sustento con nuevas evidencias a su favor. En particular, con el hallazgo de las vías involucradas y con la aplicación de conocimientos neurofisiológicos, la teoría de la inadecuación tensión y longitud se vería refinada con la descarga corolaria o copia eferente. Esta descarga corolaria o copia eferente es un atributo básico del sistema nervioso, que se encuentra en el reino animal, desde los invertebrados a los primates y en la especie humana. Este artículo está dedicado a la historia de la copia eferente y su incorporación como hipótesis para explicar la disnea, la más aceptada en la actualidad.

All the theories about the mechanisms of generation of dyspnea had defenders and detractors and, interestingly, with the development of sophisticated neurophysiological techniques and functional imaging, it has been possible to rank each one of them. All have survived the passage of time and none can singularly explain dyspnea in all clini cal situations, showing the complex and multifactorial nature of the phenomenon. The concept of length-tension inappropriateness has found support in recent decades with new evidence in its favor. Specially with the discovery of the pathways involved and with the application of neurophysiological knowledge, the length-tension inappropriate ness theory would be refined with the corollary discharge or efferent copy. This corol lary discharge or efferent copy is a basic attribute of the nervous system found in the animal kingdom, from invertebrates to primates and in the human species. This article is dedicated to the history of the efferent copy and its incorporation as a hypothesis to explain dyspnea, which is currently the most accepted one.

Factors associated with mortality in mechanically ventilated patients with severe acute respiratory syndrome due to COVID-19 evolution / Fatores associados à mortalidade em pacientes ventilados mecanicamente com síndrome respiratória aguda grave por evolução da COVID-19

ABSTRACT Objectives: To evaluate the factors associated with mortality in mechanically ventilated patients with acute respiratory distress syndrome due to COVID-19. Methods: This was a retrospective, multicenter cohort study that included 425 mechanically ventilated adult patients with COVID-19 admitted to 4 intensive care units. Clinical data comprising the SOFA score, laboratory data and mechanical characteristics of the respiratory system were collected in a standardized way immediately after the start of invasive mechanical ventilation. The risk factors for death were analyzed using Cox regression to estimate the risk ratios and their respective 95%CIs. Results: Body mass index (RR 1.17; 95%CI 1.11 - 1.20; p < 0.001), SOFA score (RR 1.39; 95%CI 1.31 - 1.49; p < 0.001) and driving pressure (RR 1.24; 95%CI 1.21 - 1.29; p < 0.001) were considered independent factors associated with mortality in mechanically ventilated patients with acute respiratory distress syndrome due to COVID-19. Respiratory system compliance (RR 0.92; 95%CI 0.90 - 0.93; p < 0.001) was associated with lower mortality. The comparative analysis of the survival curves indicated that patients with respiratory system compliance (< 30mL/cmH2O), a higher SOFA score (> 5 points) and higher driving pressure (> 14cmH2O) were more significantly associated with the outcome of death at 28 days and 60 days. Conclusion: Patients with a body mass index > 32kg/m2, respiratory system compliance < 30mL/cmH2O, driving pressure > 14cmH2O and SOFA score > 5.8 immediately after the initiation of invasive ventilatory support had worse outcomes, and independent risk factors were associated with higher mortality in this population.

RESUMO Objetivos: Avaliar os fatores associados à mortalidade em pacientes ventilados mecanicamente com síndrome o desconforto respiratório agudo por evolução da COVID-19. Métodos: Estudo de coorte retrospectiva, multicêntrica, que incluiu 425 pacientes adultos com COVID-19, ventilados mecanicamente, internados em 4 unidades de terapia intensiva. Foram coletados dados clínicos que compõem o escore SOFA, dados laboratoriais e características mecânicas do sistema respiratório, de forma padronizada, imediatamente após o início da ventilação mecânica invasiva. Os fatores de risco para óbito foram analisados por meio da regressão de Cox, para estimar as razões de risco, e seus respectivos IC95%. Resultados: Índice de massa corporal (RR de 1,17; IC95% 1,11 - 1,20; p < 0,001), escore SOFA (RR de 1,39; IC95% 1,31 - 1,49; p < 0,001) e driving pressure (RR de 1,24; IC95% 1,21 - 1,29; p < 0,001) foram considerados fatores independentes associados à mortalidade em pacientes ventilados mecanicamente com síndrome do desconforto respiratório agudo por COVID-19. Já a complacência do sistema respiratório (RR de 0,92; IC95% 0,90 - 0,93; p < 0,001) foi associada à menor mortalidade. A análise comparativa das curvas de sobrevida demonstra que pacientes com complacência do sistema respiratório (< 30mL/cmH2O), maior SOFA escore (> 5 pontos) e maior driving pressure (> 14cmH2O) apresentaram maior associação ao desfecho morte em 28 dias e 60 dias. Conclusão: Pacientes com índice de massa corporal > 32kg/m2, complacência do sistema respiratório < 30mL/cmH2O, driving pressure > 14cmH2O e SOFA escore > 5,8, imediatamente após o início da assistência ventilatória invasiva, apresentam piores desfechos no segmento, sendo fatores de risco independentes associados à maior mortalidade nessa população.

[Effects of different levels of end-expiratory pressure on hemodynamic, respiratory mechanics and systemic stress response during laparoscopic cholecystectomy]. / Efeitos de diferentes níveis de pressão expiratória final sobre a hemodinâmica, mecânica respiratória e resposta sistêmica ao estresse durante colecistectomia laparoscópica.

OBJECTIVE: General anesthesia causes reduction of functional residual capacity. And this decrease can lead to atelectasis and intrapulmonary shunting in the lung. In this study we want to evaluate the effects of 5 and 10cmH2O PEEP levels on gas exchange, hemodynamic, respiratory mechanics and systemic stress response in laparoscopic cholecystectomy. METHODS: American Society of Anesthesiologist I-II physical status 43 patients scheduled for laparoscopic cholecystectomy were randomly selected to receive external PEEP of 5cmH2O (PEEP 5 group) or 10cmH2O PEEP (PEEP 10 group) during pneumoperitoneum. Basal hemodynamic parameters were recorded, and arterial blood gases (ABG) and blood sampling were done for cortisol, insulin and glucose level estimations to assess the systemic stress response before induction of anesthesia. Thirty minutes after the pneumoperitoneum, the respiratory and hemodynamic parameters were recorded again and ABG and sampling for cortisol, insulin, and glucose levels were repeated. Lastly hemodynamic parameters were recorded; ABG analysis and sampling for stress response levels were taken after 60minutes from extubation. RESULTS: There were no statistical differences between the two groups about hemodynamic and respiratory parameters except mean airway pressure (Pmean). Pmean, compliance and PaO2; pH values were higher in 'PEEP 10 group'. Also, PaCO2 values were lower in 'PEEP 10 group'. No differences were observed between insulin and lactic acid levels in the two groups. But postoperative cortisol level was significantly lower in 'PEEP 10 group'. CONCLUSION: Ventilation with 10cmH2O PEEP increases compliance and oxygenation, does not cause hemodynamic and respiratory complications and reduces the postoperative stress response.

Effects of different levels of end-expiratory pressure on hemodynamic, respiratory mechanics and systemic stress response during laparoscopic cholecystectomy.

OBJECTIVE: General anesthesia causes reduction of functional residual capacity. And this decrease can lead to atelectasis and intrapulmonary shunting in the lung. In this study we want to evaluate the effects of 5 and 10cmH2O PEEP levels on gas exchange, hemodynamic, respiratory mechanics and systemic stress response in laparoscopic cholecystectomy. METHODS: American Society of Anesthesiologist I-II physical status 43 patients scheduled for laparoscopic cholecystectomy were randomly selected to receive external PEEP of 5cmH2O (PEEP 5 group) or 10cmH2O PEEP (PEEP 10 group) during pneumoperitoneum. Basal hemodynamic parameters were recorded, and arterial blood gases (ABG) and blood sampling were done for cortisol, insulin and glucose level estimations to assess the systemic stress response before induction of anesthesia. Thirty minutes after the pneumoperitoneum, the respiratory and hemodynamic parameters were recorded again and ABG and sampling for cortisol, insulin, and glucose levels were repeated. Lastly hemodynamic parameters were recorded; ABG analysis and sampling for stress response levels were taken after 60minutes from extubation. RESULTS: There were no statistical differences between the two groups about hemodynamic and respiratory parameters except mean airway pressure (Pmean). Pmean, compliance and PaO2; pH values were higher in 'PEEP 10 group'. Also, PaCO2 values were lower in 'PEEP 10 group'. No differences were observed between insulin and lactic acid levels in the two groups. But postoperative cortisol level was significantly lower in 'PEEP 10 group'. CONCLUSION: Ventilation with 10cmH2O PEEP increases compliance and oxygenation, does not cause hemodynamic and respiratory complications and reduces the postoperative stress response.