Differences in Exercise Capacity, Ventilatory Efficiency, and Gas Exchange between Patients with Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension Residing at High Altitude.

Background: Cardiopulmonary exercise testing (CPET) assesses exercise capacity and causes of exercise limitation in patients with pulmonary hypertension (PH). At altitude, changes occur in the ventilatory pattern and a decrease in arterial oxygen pressure in healthy; these changes are increased in patients with cardiopulmonary disease. Our objective was to compare the response to exercise and gas exchange between patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) residing at the altitude of Bogotá (2640 m). Methods: All patients performed an incremental CPET with measurement of oxygen consumption ( VO 2 ), dead space (VD/VT), ventilatory equivalents (VE/ VCO 2 ), and alveolar-arterial oxygen gradient ( PA-aO 2 ). X 2 test and one-way analysis of variance were used for comparisons between PAH and CTEPH. Results: We included 53 patients, 29 with PAH, 24 with CTEPH, and 102 controls as a reference of the normal response to exercise at altitude. CTEPH patients had a higher New York Health Association (NYHA) functional class than PAH (p = 0.037). There were no differences between patients with PAH and CTEPH in hemodynamics and VO 2 % of predicted (67.8 ± 18.7 vs. 66.0 ± 19.8, p < 0.05), but those with CTEPH had higher dyspnea, VD/VT (0.36 ± 0.09 vs. 0.23 ± 0.9, p < 0.001), VE/ VCO 2 (45.8 ± 7.1 vs. 39.3 ± 5.6, p < 0.001), and PA-aO 2 (19.9 ± 7.6 vs. 13.5 ± 7.6, p < 0.001) than PAH patients. Conclusions: At altitude, patients with PH present severe alterations in gas exchange during exercise. There were no differences in exercise capacity between PAH and CTEPH, but patients with CTEPH had more dyspnea and greater alterations in gas exchange during exercise. CPET made it possible to identify alterations related to the pathophysiology of CTEPH that could explain the functional class and dyspnea in these patients.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Anemia tolerance mechanisms.

Understanding the physiological concepts of oxygen delivery is essential to discern the mechanisms that influence its increase, reduction or maintenance in the body. This text explores the different mechanisms that help maintain oxygen delivery even in the face of reduced hemoglobin levels. Adequate oxygen delivery ensures tissue and metabolic balance, which is crucial to avoid harmful consequences such as metabolic acidosis and cellular dysoxia. The complex interaction between variables such as cardiac output, hemoglobin and heart rate (HR) plays a fundamental role in maintaining oxygen delivery, allowing the body to temporarily adjust to situations of anemia or high metabolic demand. It is important to emphasize that blood transfusions should not be based on fixed values, but rather on individual metabolic needs. Strategies to reduce myocardial consumption and monitor macro and micro hemodynamics help in making rational decisions. Individualizing treatment and considering factors such as blood viscosity in relation to the benefits of transfusion are increasingly relevant to optimize therapy and minimize risks, especially in complex clinical scenarios, such as neurocritical patients and trauma victims.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Anemia tolerance mechanisms

Abstract Understanding the physiological concepts of oxygen delivery is essential to discern the mechanisms that influence its increase, reduction or maintenance in the body. This text explores the different mechanisms that help maintain oxygen delivery even in the face of reduced hemoglobin levels. Adequate oxygen delivery ensures tissue and metabolic balance, which is crucial to avoid harmful consequences such as metabolic acidosis and cellular dysoxia. The complex interaction between variables such as cardiac output, hemoglobin and heart rate (HR) plays a fundamental role in maintaining oxygen delivery, allowing the body to temporarily adjust to situations of anemia or high metabolic demand. It is important to emphasize that blood transfusions should not be based on fixed values, but rather on individual metabolic needs. Strategies to reduce myocardial consumption and monitor macro and micro hemodynamics help in making rational decisions. Individualizing treatment and considering factors such as blood viscosity in relation to the benefits of transfusion are increasingly relevant to optimize therapy and minimize risks, especially in complex clinical scenarios, such as neurocritical patients and trauma victims.

Lactate and base excess (BE) as markers of hypoperfusion and mortality in traumatic hemorrhagic shock in patients undergoing Damage Control: a historical cohort / Lactato e excesso de base (BE) como marcadores de hipoperfusão e mortalidade no choque hemorrágico traumático em pacientes submetidos à estratégia de controle de danos - Uma coorte histórica

ABSTRACT Introduction: hemorrhagic shock is a significant cause of trauma-related deaths in Brazil and worldwide. This study aims to compare BE and lactate values at ICU admission and twenty-four hours after in identifying tissue hypoperfusion and mortality. Methods: examines a historical cohort of trauma patients over eitheen years old submittet to damage control resuscitation approch upon hospital admission and were then admitted to the ICU. We collected and analyzed ISS, mechanism and type of trauma, need for renal replacement therapy, massive transfusion. BE, lactate, pH, bicarbonate at ICU admission and twenty-four hours later, and mortality data. The patients were grouped based on their BE values (≥-6 and <-6mmol/L), which were previously identified in the literature as predictors of severity. They were subsequently redivided using the most accurate values found in this sample. In addition to performing multivariate binary logistic regression. The data were compared using several statistical tests due to diversity and according to the indication for each variable. Results: there were significant changes in perfusion upon admission to the Intensive Care Unit. BE is a statistically significant value for predicting mortality, as determined by using values from previous literature and from this study. Conclusion: the results demonstrate the importance of monitoring BE levels in the prediction of ICU mortality. BE proves to be a valuable bedside marker with quick results and wide availability.

RESUMO Introdução: o choque hemorrágico é a principal causa reversível de morte no trauma no Brasil e no mundo. Objetivo: comparar o valor de BE ao do lactato na admissão da UTI e vinte e quatro horas após o internamento na identificação de hipoperfusão tecidual e predição de mortalidade Método: coorte histórica de pacientes traumatizados, maiores de dezoito anos, submetidos à estratégia de controle de danos na admissão hospitalar, seguido de internamento em UTI. Foram coletados e analisados ISS, mecanismo e tipo de trauma, necessidade de terapia de substituição renal e transfusão maciça; BE, lactato, pH e bicarbonato coletados na admissão da UTI e vinte e quatro horas após, e a mortalidade. Os pacientes foram divididos em grupos conforme valores de BE (≥-6 e <-6mmol/L) já descritos na literatura como preditores de gravidade, e após redivididos de acordo com os valores de melhor acurácia encontrados nesta amostra, além de realização de regressão logística binária multivariada. Os dados foram comparados através de diversos testes estatísticos devido a diversidade e conforme a indicação para cada variável. Resultados: houve alterações perfusionais impactantes já na admissão da UTI. BE manteve-se com valor estatisticamente significativo para predição de mortalidade tanto quando utilizado os valores já conhecidos da literatura como quando aplicados os valores neste estudo identificados. Conclusão: valores de BE e de lactato foram capazes de predizer hipoperfusão tecidual e mortalidade nos dois momentos estudados, quando comparados, o BE tem boa performance como preditor de mortalidade, com rápido resultado e ampla disponibilidade.

Analysis of Different Tidal Volumes on Ventilatory Mechanics and Arterial Blood Gas Variables in Patients Undergoing Cardiac Surgery.

Introduction: Cardiovascular diseases have been increasing gradually each year, and their incidence has reached 80%. Mechanical ventilation (MV) is essential in the postoperative period of cardiac surgery (CS) due to anesthetic induction. The tidal volume (TV) is a parameter that depends on the conditions of the respiratory system mechanics, aiming at the reduction of dynamic hyperinflation. Objective: Analyze the effect of different TVs on blood gas analysis variables and respiratory mechanics in patients submitted to CS. Materials and methods: This was an uncontrolled randomized clinical trial. Patients were randomized by lottery into the following two groups: One group was ventilated with a TV of 6 mL/kg; while the other received a TV of 8 mL/kg. After 30 minutes of admission with the VT, blood gas analysis data were evaluated, such as pH, oxygen arterial pressure (PaO2), arterial pressure of carbon dioxide (PaCO2), and peripheral oxygen saturation (SpO2). The evaluation of respiratory mechanics was composed of static and dynamic compliance, airway resistance, and driving pressure. Results: A total of 78 patients were included, 58% of whom were males with a mean age of 55 ± 13 years. It was observed that there were no significant differences regarding respiratory mechanics, only the driving pressure presented statistical significance, the group 6 mL/kg was 8.3 ± 2.5 in the group 8 mL/kg 10.4 ± 2.1 presenting a value of (p < 0.001). Conclusion: Based on the findings of the present study, we conclude that different TVs do not significantly alter the blood gas variables and do not influence the respiratory mechanics of patients undergoing CS. How to cite this article: Cordeiro A, Souza A, de Brito Lima CR, Araújo J, Mascarenhas H, Guimarães A. Analysis of Different Tidal Volumes on Ventilatory Mechanics and Arterial Blood Gas Variables in Patients Undergoing Cardiac Surgery. Indian J Crit Care Med 2023;27(12):930-933.

[Response to comment on the article "Variability of hemoglobin and hematocrit determined in blood gas equipment"]. / Response to comment on the article "Variability of hemoglobin and hematocrit determined in blood gas equipment".

Hemoglobin and hematocrit are parameters widely used. They can be obtained from an automated hematology analyzer or from an arterial blood gas analyzer. Its variability is shown in the article "Variability of hemoglobin and hematocrit determined in blood gas equipment." Clinical and statistical information requested is extended for a better understanding of the article and its conclusions. It is suggested to carry out an analysis of variability in parameters and laboratory equipment.

La hemoglobina y el hematocrito son parámetros de amplio uso. Pueden ser obtenidos de un analizador automatizado de hematología o de un analizador de gases arteriales. Su variabilidad se muestra en el artículo "Variabilidad de la hemoglobina y hematocrito determinados en equipo de gases sanguíneos". Se amplía la información clínica y estadística solicitada para la mejor comprensión del trabajo y sus conclusiones. Se sugiere hacer un análisis de variabilidad en parámetros y equipos de laboratorios.

Comparison of two sedation protocols for diagnostic radiography in dogs with hip dysplasia.

Hip dysplasia is an alteration with a high incidence in large dogs. The aim of the study was to compare the association of xylazine or dexmedetomidine with fentanyl for radiography with joint distractor for the diagnosis of hip dysplasia. Fifteen healthy dogs, German Shepherd and Belgian Shepherd, were randomly submitted to treatments 0.2 mg/kg xylazine + 2.5 µg/kg fentanyl (XF) or 2 µg/kg dexmedetomidine + 2.5 µg/kg fentanyl (DF), intravenously. HR, f, SAP, MAP, DAP and TR were evaluated at intervals of 5 min before and after the administration of treatments; pH, PaCO2, PaO2, BE, HCO3-, SaO2, Na+, K+ and Hb at 5 and 15 min after treatment administration; and the quality of sedation at intervals of 5 min after administration of treatments. Latency, duration, and recovery times were also compared. The HR values showed a significant reduction in both groups, as well as pH, PaCO2, PaO2 and SaO2. Latency, duration and recovery times, and quality of sedation did not differ statistically between groups. Xylazine and fentanyl or dexmedetomidine and fentanyl combinations provide adequate sedation and analgesia for performing diagnostic radiographic procedures for hip dysplasia. However, oxygen supplementation is recommended to increase protocol safety.

Effects of pre-analytical sample care and analysis methodology on measures of metabolic acidosis in hemodialysis patients.

INTRODUCTION: We evaluated the effects of pre-analytical care on total carbon dioxide (tCO2 ) in hemodialysis patients, as calculated by blood gas analysis (ctCO2 ) or measured by an enzymatic assay (mtCO2 ). METHODS: Blood samples were collected via vascular access before dialysis sessions. For blood gas analysis, eight aliquots were collected, refrigerated or non-refrigerated, and analyzed at 0, 4, 8, and 24 h after collection. A blood sample was then collected for the enzymatic method and distributed into 14 aliquots. Half of the aliquots were refrigerated. The samples analyzed at time point 0 were centrifuged immediately. The remaining aliquots of both the refrigerated and non-refrigerated clusters were centrifuged before storage. Samples were analyzed at 4, 8, and 24 h post-collection. FINDINGS: By blood gas analysis, no significant change was found in bicarbonate values over time, either in the non-refrigerated or refrigerated samples. ctCO2 values during the experiment showed a minor but statistically significant increase of questionable clinical relevance in both non-refrigerated and refrigerated aliquots. In the enzymatic assay, the reduction in mtCO2 levels during the experiment was negligible. The median absolute reductions at the end of the experiment were 1.77, 1.21, 1.04, and 1.12 mmol/L for the non-centrifuged/non-refrigerated, centrifuged/non-refrigerated, non-centrifuged/refrigerated, and centrifuged/refrigerated aliquots, respectively. DISCUSSION: Our results suggest that measured or calculated tCO2 levels of capped and cooled samples are adequate for analyzing the acid-base status of hemodialysis patients, even when such determination is not performed immediately after collection.

[Comment on article "Variability of hemoglobin and hematocrit determined in blood gas equipment"]. / Comentario al artículo "Variabilidad de la hemoglobina y hematocrito determinados en equipo de gases sanguíneos".

´The analysis of samples on different equipment may lead to variation between results; in the article "Variability of hemoglobin and hematocrit determined in blood gas equipment", the authors talk about the variability of hemoglobin and hematocrit between an automated hematology analyzer and an arterial blood gas analyzer. Information is requested on some aspects considered relevant to improve the understanding of the conclusions.

El análisis de muestras en diferentes equipos puede conllevar una variación entre los resultados; en el artículo "Variabilidad de la hemoglobina y hematocrito determinados en equipo de gases sanguíneos", sus autores hablan de la variabilidad de hemoglobina y hematocrito entre un analizador automatizado de hematología y un analizador de gases arteriales. Se solicita información sobre algunos aspectos considerados relevantes para mejorar la compresión de las conclusiones.

Pyometra in queens - changes in haemato-biochemical parameters

Background: Pyometra is a bacterial and hormone-induced reproductive disease that occurs in the post-estrus luteal phase in intact queens. Pyometra is more common in the diestrus period due to the high progesterone concentration (in queens that mated, spontaneously ovulated, or were induced to ovulate). However, it can also be seen due to the use of exogenous hormones such as progesterone for the suppression of estrus. More research is needed in cases of pyometra in queens, as well as in bitches. Because, considering that the pathogenesis and characteristics of feline pyometra is similar to bitches, studies on pyometra-affected bitches are taken as reference in studies and applications on queens. From this point of view, the aims of this study were to reveal the changes in complete blood count, blood gas, and serum biochemistry parameters in feline pyometra cases and to determine the correlation between the mentioned parameters. Materials, Methods & Results: In the study, a total of 25 female cats of different breeds were used, between the ages of 6 months and 7 years, 15 were diagnosed with pyometra, and 10 healthy. Anamnesis, clinical findings, and ultrasonographic examinations were used in the diagnosis of pyometra. Abdominal ultrasonography was performed on queens brought to the clinic with complaints such as anorexia, polydipsia, polyuria, abdominal tension, and fever. The control group (n =10) consisted of queens that were introduced to the clinic and were reproductively healthy. Before any treatment in queens with pyometra and the control group, 1 mL blood samples were taken from v. cephalica to evaluate complete blood count, blood gases and serum biochemistry parameters. In complete WBC, Lym, Mon, Gra, RBC, Hb, HCT, MCV, MCH and PLT parameters and, blood gas parameters such as pH, pCO2 , pO2 , sO2 , Na, K, Cl, lactate, glucose, HCO3 , and BE were also evaluated in taken blood samples. Biochemical parameters BUN, creatinine, ALT, AST, ALP, amylase, T.BIL, D.BIL, P, CHOL, TG, LDH, TP, CPK, ALP, Ca, GGT were measured in serum samples. After examination and laboratory analysis, ovariohysterectomy was performed on queens as a treatment. Granulocyte, WBC, HCT and MCH levels of the pyometra group were higher (P < 0.05) and Lym levels were lower (P < 0.05) compared to the control group. According to these results, pH, HCO3 , and BE were lower (P < 0.05) in queens with pyometra than those in the control group, while Na and lactate parameters were higher (P < 0.05). According to the results of biochemical analysis, it was determined that BUN, creatinine levels, GGT, and LDH enzyme activities were found to be higher in the pyometra group compared to the control group, while the Ca level was found to be low (P < 0.05). A positive correlation was observed between BUN and creatinine and LDH, WBC, granulocyte, HCT, and lactate, and a negative correlation between lymphocytes, pH, and BE in the correlation analysis performed on queens with pyometra and control group. However, a positive correlation was observed between creatinine and LDH and HCT, and a negative correlation between lymphocyte, pH and BE. Discussion: There is not enough information about pyometra in queens. As a result, it was determined that there were significant changes in complete blood count, blood gases and serum biochemical parameters in queens with pyometra in this study. These changes were generally thought to be related to dehydration and sepsis or endotoxemia. In addition, it was evaluated that prerenal azotemia occurring in pyometra affected queens may cause renal dysfunction. For this reason, it is thought that the results obtained in the presented study may contribute to the diagnosis, treatment, and prognosis of pyometra cases in queens.

Cardiorespiratory effects of different intraabdominal pressures in sheep: An experimental study.

Increased intraabdominal pressure (IAP) during laparoscopy can reduce venous return, but changes in respiratory system mechanics and their effect in left cardiac function are not well documented. This study evaluated the effects of different IAPs on respiratory mechanics and cardiac function in 10 healthy nonpregnant adult Santa Ines ewes randomly submitted to a crossover study using different IAPs: 0 mm Hg (G1), 10 mm Hg (G2), 12 mmHg (G3), and 15 mmHg (G4). Animals were anesthetized and mechanically ventilated (VT  = 15 ml/kg; positive end-expiratory pressure = 3 cmH2 O; FiO2  = 1.0). Pneumoperitoneum was induced by Hasson's trocar cannula. Variables were measured at INITIAL (IAP, 0 mmHg) and FINAL time points for each IAP after 1 h. At FINAL, driving airway pressure (ΔP,RS ), and percentage fraction of dead space (Vd/Vt) were higher in G3 and G4 than G1 (p = 0.002, difference in means [MD] 4.60, 95% CI: 7.91-1.28, and p < 0.001, MD 5.4, 95% CI: 8.7-2.0; p = 0.016, MD -9.5, 95% CI: -17.9 to -1.2; and p = 0.027, MD -8.7, 95% CI: -17.1 to -0.4). The ejection fraction and fractional shortening were lower in G3 (p = 0.039, MD -11.38, 95% CI: -0.07--22.68; p = 0.015, MD -13.05, 95% CI: -1.74--24.36) and G4 (p = 0.039, MD -9.94, 95% CI: -0.07 to -19.80; p = 0.015, MD -11.43, 95%CI: -1.57 to -21.30, respectively) than G2. In G3, the maximum pulmonary flow velocity correlated negatively with ΔP,RS (r = -0.740; p = 0.018), and Vd/Vt correlated positively with ΔP,RS (r = 0.738, p = 0.046). At IAP of 12 and 15 mm Hg impaired respiratory system mechanics, reduced left cardiac function and no change in maximum pulmonary artery flow velocity were detected. Therefore, respiratory mechanics should be monitored as an interplay to reduce left cardiac function.

[Variability of hemoglobin and hematocrit determined in blood gas equipment]. / Variabilidad de la hemoglobina y hematocrito determinados en equipo de gases sanguíneos.

Background: Usually hemoglobin and hematocrit are obtained from peripheral venous blood samples processed in equipment for hematic biometry. These parameters can also be determined from arterial samples processed on blood gas equipment. Its variability when using arterial samples and this equipment is unknown, in addition, if the lack of knowledge of this variability affects clinical decisions. Objective: To know the variability of hemoglobin and hematocrit from arterial blood samples processed in blood gas equipment. Material and methods: Analytic cross design. Consecutive subjects with stable cardiopulmonary disease were blindly studied. The samples were obtained at the same time for analysis in both equipments. Variability was analyzed with Bland-Altman descriptive statistic and its magnitude with the intraclass correlation coefficient. Results: Two hundred of blood samples from 50 patients were studied, 31 (62%) women, age 62 ± 14 years old, body mass index 30.11 ± 5.69 Kg/m2. The main comparison was peripheral venous blood sample processed in laboratory equipment (SYSMEX) vs. arterial sample on blood gas equipment (GEM). The mean difference (bias) and intraclass correlation coefficient for hemoglobin were: 0.12 (-1.45, 1.23) and 0.95 (0.91, 0.97); for the hematocrit -4.4 (-0.4, 8.54), and 0.72 (0.51, 0.84). Conclusions: The mean difference and bias for hemoglobin was close to 0; the hematocrit was higher. Hemoglobin from arterial samples processed in blood gas equipment can be used to make clinical decisions.

Introducción: usualmente, la hemoglobina y el hematocrito se obtienen de sangre venosa periférica procesada en equipo convencional para biometría hemática, también pueden ser determinados de muestras arteriales procesadas en equipos para gases sanguíneos. Se desconoce su variabilidad al utilizar muestras arteriales y equipos para gases sanguíneos, además, si esta variabilidad pudiera afectar las decisiones clínicas. Objetivo: conocer la variabilidad de la hemoglobina y hematocrito de muestras sanguíneas arteriales procesadas en equipo de gases sanguíneos. Material y métodos: diseño transversal analítico. Se estudiaron de forma ciega sujetos consecutivos con enfermedad cardiopulmonar estable. Las muestras sanguíneas se adquirieron al mismo tiempo para su análisis en ambos equipos. La variabilidad se analizó con el estadístico descriptivo de Bland-Altman y su magnitud con el coeficiente de correlación intraclase. Resultados: se analizaron 200 muestras sanguíneas de 50 pacientes, 31 (62%) mujeres, edad grupal 62 ± 14 años, índice de masa corporal 30.11 ± 5.69 Kg/m2. La principal comparación: muestra sanguínea venosa periférica procesada en equipo del laboratorio (SYSMEX) frente a muestra arterial en equipo de gases sanguíneos (GEM). La diferencia media (sesgo) y el coeficiente de correlación intraclase de la hemoglobina fueron: 0.12 (-1.45, 1.23) y 0.95 (0.91, 0.97); hematocrito -4.4 (-0.4, 8.54) y 0.72 (0.51, 0.84). Conclusiones: la diferencia media y sesgo de la hemoglobina fue cercana a 0; la del hematocrito fue mayor. La hemoglobina de muestras arteriales procesadas en equipos de gases sanguíneos son útiles para tomar decisiones clínicas.

Justificativa e limitações da SpO2/FiO2 como possível substituta da PaO2/FiO2 em diferentes cenários pré-clínicos e clínicos / Rationale and limitations of the SpO2/FiO2 as a possible substitute for PaO2/FiO2 in different preclinical and clinical scenarios

RESUMO Embora a PaO2/FiO2 derivada da gasometria arterial continue sendo o padrão-ouro do diagnóstico de insuficiência respiratória aguda, a SpO2/FiO2 tem sido investigada como potencial substituta. Esta revisão narrativa apresenta o estado da literatura pré-clínica e clínica sobre a SpO2/FiO2 como possível substituta da PaO2/FiO2 e para uso como marcador diagnóstico e prognóstico; ainda, é fornecida uma visão geral da oximetria de pulso e suas limitações, além da avaliação da utilidade da SpO2/ FiO2 como substituta da PaO2/FiO2 em pacientes com COVID-19. Ao todo, foram encontrados 49 estudos comparando SpO2/FiO2 e PaO2/ FiO2 com base em uma estratégia de pesquisa mínima. A maioria dos estudos foi realizada em recémnascidos, alguns foram realizados em adultos com síndrome do desconforto respiratório agudo, e outros foram realizados em outros cenários clínicos (incluindo poucos em pacientes com COVID-19). Há certa evidência de que os critérios de SpO2/FiO2 podem substituir a PaO2/FiO2 em diferentes cenários clínicos. Isso é reforçado pelo fato de que devem ser evitados procedimentos invasivos desnecessários em pacientes com insuficiência respiratória aguda. É inegável que os oxímetros de pulso estão cada vez mais difundidos e podem proporcionar um monitoramento sem custos. Portanto, substituir a PaO2/FiO2 pela SpO2/FiO2 pode permitir que instalações com recursos limitados diagnostiquem a insuficiência respiratória aguda de maneira objetiva.

ABSTRACT Although the PaO 2/FiO 2 derived from arterial blood gas analysis remains the gold standard for the diagnosis of acute respiratory failure, the SpO2/FiO2 has been investigated as a potential substitute. The current narrative review presents the state of the preclinical and clinical literature on the SpO2/FiO2 as a possible substitute for PaO2/FiO2 and for use as a diagnostic and prognostic marker; provides an overview of pulse oximetry and its limitations, and assesses the utility of SpO2/ FiO2 as a surrogate for PaO2/FiO2 in COVID-19 patients. Overall, 49 studies comparing SpO2/FiO2 and PaO2/FiO2 were found according to a minimal search strategy. Most were conducted on neonates, some were conducted on adults with acute respiratory distress syndrome, and a few were conducted in other clinical scenarios (including a very few on COVID-19 patients). There is some evidence that the SpO2/ FiO2 criteria can be a surrogate for PaO2/FiO2 in different clinical scenarios. This is reinforced by the fact that unnecessary invasive procedures should be avoided in patients with acute respiratory failure. It is undeniable that pulse oximeters are becoming increasingly widespread and can provide costless monitoring. Hence, replacing PaO2/FiO2 with SpO2/FiO2may allow resourcelimited facilities to objectively diagnose acute respiratory failure.

Sildenafil for treating patients with COVID-19 and perfusion mismatch: a pilot randomized trial.

BACKGROUND: SARS-CoV-2 seems to affect the regulation of pulmonary perfusion. Hypoperfusion in areas of well-aerated lung parenchyma results in a ventilation-perfusion mismatch that can be characterized using subtraction computed tomography angiography (sCTA). This study aims to evaluate the efficacy of oral sildenafil in treating COVID-19 inpatients showing perfusion abnormalities in sCTA. METHODS: Triple-blinded, randomized, placebo-controlled trial was conducted in Chile in a tertiary-care hospital able to provide on-site sCTA scans and ventilatory support when needed between August 2020 and March 2021. In total, 82 eligible adults were admitted to the ED with RT-PCR-confirmed or highly probable SARS-COV-2 infection and sCTA performed within 24 h of admission showing perfusion abnormalities in areas of well-aerated lung parenchyma; 42 were excluded and 40 participants were enrolled and randomized (1:1 ratio) once hospitalized. The active intervention group received sildenafil (25 mg orally three times a day for seven days), and the control group received identical placebo capsules in the same way. Primary outcomes were differences in oxygenation parameters measured daily during follow-up (PaO2/FiO2 ratio and A-a gradient). Secondary outcomes included admission to the ICU, requirement of non-invasive ventilation, invasive mechanical ventilation (IMV), and mortality rates. Analysis was performed on an intention-to-treat basis. RESULTS: Totally, 40 participants were enrolled (20 in the placebo group and 20 in the sildenafil group); 33 [82.5%] were male; and median age was 57 [IQR 41-68] years. No significant differences in mean PaO2/FiO2 ratios and A-a gradients were found between groups (repeated-measures ANOVA p = 0.67 and p = 0.69). IMV was required in 4 patients who received placebo and none in the sildenafil arm (logrank p = 0.04). Patients in the sildenafil arm showed a significantly shorter median length of hospital stay than the placebo group (9 IQR 7-12 days vs. 12 IQR 9-21 days, p = 0.04). CONCLUSIONS: No statistically significant differences were found in the oxygenation parameters. Sildenafil treatment could have a potential therapeutic role regarding the need for IMV in COVID-19 patients with specific perfusion patterns in sCTA. A large-scale study is needed to confirm these results. TRIAL REGISTRATION: Sildenafil for treating patients with COVID-19 and perfusion mismatch: a pilot randomized trial, NCT04489446, Registered 28 July 2020, https://clinicaltrials.gov/ct2/show/NCT04489446 .

Clinical and laboratory evaluation of premature goat kids with and without antenatal corticotherapy / Avaliação clínica e laboratorial de cabritos prematuros com e sem corticoterapia antenatal

This article evaluated the vital parameters, blood gas measurements, cortisol values and radiological findings of goat kids born at term and prematurely during the first 48 hours of life. For this purpose, 24 kids from 24 goats were used and assigned to groups as follows: Group I, eight kids born through cesarean sections performed at 149 days of gestation; Group II, eight kids born through cesarean sections performed at 143 days of gestation; Group III, eight kids born through cesarean sections performed at 143 days of gestation, whose mothers received 20 mg of dexamethasone. Group I had lower heart rate values than the other groups at 60 minutes after birth. In terms of temperature, there was no difference between the groups. The pH values were reduced shortly after birth, rising at 24 and 48 hours in all animals studied. In terms of the cortisol levels, the values increased significantly at birth (M0), with the highest values obtained in animals in group II. These values decreased at 48 hours after birth in the evaluated goats. The animals belonging to group I showed better radiographic aspects, and throughout the 48 hours of evaluation, all newborns exhibited adequate respiratory adaptation. It can be concluded that antenatal dexamethasone administered at 143 days of gestation did not influence neonatal viability, metabolic or radiographic parameters. The metabolic changes found are consistent with the extrauterine adaptation period that animals in this stage of life.

O presente artigo teve como objetivo avaliar os parâmetros vitais, hemogasométricos, valores de cortisol e os achados radiológicos, de cabritos nascidos a termo e prematuros, durante as primeiras 48 horas de vida. Para tanto, foram utilizados 24 cabritos oriundos de 20 cabras, distribuídos nos grupos: grupo I: oito cabritos nascidos por meio de cesarianas realizadas aos 149 dias de gestação; grupo II: oito cabritos nascidos por meio de cesarianas realizadas aos 143 dias de gestação; grupo III: oito cabritos nascidos por meio de cesarianas realizadas aos 143 dias de gestação, cujas mães receberam 20 mg de dexametasona. O grupo I apresentou valores mais baixos de frequência cardíaca quando comparados aos demais grupos aos 60 minutos após o nascimento. Em relação à temperatura, não houve diferença entre os grupos nos momentos avaliados. Os valores de pH apresentaram-se diminuídos logo após o nascimento, vindo a elevar-se nos momentos 24 e 48 horas em todos animais estudados. Em relação à análise dos níveis de cortisol, os valores aumentaram de forma significativa no (M0), com os maiores valores obtidos nos animais do grupo II. Esses valores decresceram às 48 horas após o nascimento nos cabritos avaliados. Os animais pertencentes ao grupo I demonstraram melhores aspectos radiográficos, sendo que, ao longo das 48 horas de avaliação, todos os recém-nascidos possuíam adequada adaptação respiratória. Conclui-se que a dexametasona antenatal realizada aos 143 dias de gestação não exerceu influência sobre a viabilidade neonatal, parâmetros metabólicos e radiográficos. As alterações metabólicas encontradas são condizentes com o período de adaptação extrauterina que animais nessa fase de vida enfrentam.

The effect of size and clinical staging of mammary tumors on blood parameters in bitches

Background: Mammary tumors are the most common type of tumor in female dogs and account for 50% of all tumors in dogs. The clinical prognosis of canine mammary tumors is strongly affected by the size, stages, histological type, and grade of tumor; mitotic index; and nearby and distant metastasis. In canine mammary tumors, it is recommended that prognostic evaluation should also include complete blood count, serum biochemistry, and blood gases in addition to tumor size and stage. This study aimed to investigate the effect of tumor size, volume, and clinical stage on complete blood count, blood gas analysis, and serum biochemical parameters in bitches with mammary tumors and the correlation between them. Materials, Methods & Results: The study included a total of 18 bitches of different breeds, aged 6-15 years, of which 12 had mammary tumors and 6 were healthy. Thoracic X-rays were performed on bitches with mammary tumors in ventrodorsal and laterolateral positions to evaluate lung metastasis. Blood samples were collected from the cephalic vein from bitches in both groups in 2 different tubes (with plastic gel and ethylenediaminetetraacetic acid), 5 mL each, to perform complete blood count and evaluate blood gases and serum biochemical parameters. Blood samples were collected from the animals at the time of initial examination without any intervention. Analysis of the blood showed that bitches with mammary tumors had decreased levels of RBC, HCT, HGB, potassium, TCO2 , base excess, THbc, and ALT enzyme activity and increased levels of lactate, total protein, cholesterol, triglyceride, LDL, uric acid, and ALP and LDH enzyme activities compared with those in the control group. Furthermore, the dogs with a primary tumor of > 5 cm were found to have significantly higher levels of WBC, lactate, total protein, triglyceride, LDL, uric acid, and ALP and LDH enzyme activities and significantly lower levels of RBC and THbc compared with those in the control group. Bitches with tumors in multiple mammary lobes were found to have significantly higher levels of WBC, total protein, triglyceride, LDL, and ALP and LDH enzyme activities and significantly lower levels of RBC, HCT, HGB, TCO2 , THbc, and ALT enzyme activity compared with those in the control group. Based on the laboratory findings and approval of the owners of the dogs, mammary tissues containing the tumor and lymph nodes were surgically removed. After the operation, the removed mammary tissues were evaluated for size and volume. Clinical staging of the tumors was performed based on the size of the primary tumor (T), nearby lymph nodes (N), and metastasis (M) in accordance with the criteria set by WHO. Clinical staging of the tumors was, thus, based on the tumor, nodes, and metastases (TNM) score obtained according to the following system: Stage I: T1 N0 M0 , Stage II: T2 N0 M0 , Stage III: T3 N0 M0 , Stage IV: TanyN1 M0 , Stage V: made as TanyNanyM1 . Discussion: Mammary tumors are the most common type of neoplasm in bitches and, thus, cause serious problems in veterinary medicine. Tumors are significantly correlated with better prognosis compared with larger tumors. Based on this finding, this study investigated the effect of size, volume, and stage of mammary tumors in bitches on some blood parameters and the correlation between them. Therefore, it was concluded that clinical staging and evaluation of blood parameters could be useful in the diagnosis, treatment, and prediction of prognosis in canine mammary tumors. This study found that bitches with mammary tumors exhibited significant changes in their blood parameters (complete blood count, blood gas analysis, and serum biochemistry). The results obtained from this study may contribute to the development of approaches to the diagnosis, prediction of prognosis, and treatment of canine mammary tumors.

Fisiología respiratoria: relación ventilación/perfusión / Respiratory fisiology: ventilation/perfusion relationship

Las alteraciones de la relación entre la ventilación y el flujo sanguíneo (V/Q) en diversas regiones del pulmón alteran el aporte de oxígeno (O2) y remoción del dióxido de carbono (CO2) al organismo. Fisiológicamente existen diferencias regionales en la relación V/Q. Determinadas patologías pueden alterar esta relación, produciendo tres escenarios distintos: Cortocircuito (Shunt), Alteración V/Q y aumento del espacio muerto. Para evaluar estos escenarios y realizar una aproximación diagnostica son de utilidad el estudio de los gases arteriales y venosos, la diferencia alveolo arterial y la respuesta al suministrar O2

Alterations in the ventilation perfusion relationship (V/Q) in various lung regions alter the supply of oxygen (O2) and the removal of carbon dioxide (CO2) in the body. Physiologically, there are regional differences in the V/Q ratio. Certain pathologies can alter this relationship, producing three different scenarios: Shunt, V/Q mismach and dead space increased. To evaluate these scenarios and carry out a diagnostic approach, it is useful to study arterial and venous gasometry, the alveolar arterial difference and the response to oxygen supplying.

[Characterization of gas exchange parameters in Mexico City]. / Caracterización de parámetros del intercambio gaseoso en la Ciudad de México.

Background: At high altitude the gas exchange is impaired, in the moderate altitude of Mexico City they are not yet defined. Objective: To characterize the gas exchange in the moderate altitude of Mexico City. Material and methods: Through an analytical cross-sectional study, subjects born and inhabitants of Mexico City, both genders, aged 20 to 59 years without cardiopulmonary disease, were studied. Their demographic variables, simple spirometry and arterial blood gas were recorded. Differences in variables were calculated with one-way ANOVA for independent groups and Bonferroni adjustment. p < 0.05 was accepted as significant. Results: 335 subjects were studied, 168 (50.15%) men. Group age 45 ± 11 years old, body mass index 22.97 ± 1.54 Kg/m2. Forced expiratory volume ratio in the first second / Forced vital capacity (FEV1/FVC) 91.58 ± 12.86%. The arterial oxygen pressure was: 66 ± 5.02 mmHg, carbon dioxide: 32.07 ± 2.66 mmHg, arterial oxygen saturation: 93.0 3 ± 1.80%, and hemoglobin: 14.07 ± 1.52 gr/dL. Conclusions: The arterial oxygen pressure and carbon dioxide are lowered at the Mexico City altitude.

Introducción: en las grandes altitudes, el intercambio gaseoso suele estar deteriorado; en la altitud moderada de la Ciudad de México esto no está aún plenamente definido. Objetivo: caracterizar el intercambio gaseoso en la altitud moderada de la Ciudad de México. Material y métodos: mediante un estudio transversal analítico se estudiaron sujetos nacidos y habitantes de la Ciudad de México, de ambos géneros, con edades de 20 a 59 años sin enfermedad cardiopulmonar. Se registraron sus variables demográficas, espirometría simple y de gasometría arterial. Las diferencias en las variables se calcularon con ANOVA de una vía para grupos independientes y ajuste de Bonferroni. Una p < 0.05 se aceptó como significativa. Resultados: se estudiaron 335 sujetos, de los cuales 168 (50.15%) fueron hombres, la edad grupal fue de 45 ± 11 años, con índice de masa corporal 22.97 ± 1.54 Kg/m2. La relación volumen espiratorio forzado en el primer segundo/ Capacidad vital forzada (VEF1/CVF) de 91.58 ± 12.86%. La presión arterial de oxígeno fue de 66 ± 5.02 mmHg, el bióxido de carbono: 32.07 ± 2.66 mmHg, la saturación arterial de oxígeno: 93.03 ± 1.80% y la hemoglobina: 14.07 ± 1.52 gr/dL. Conclusiones: la presión arterial de oxígeno y del bióxido de carbono están disminuidos a la altura de la Ciudad de México.

Caracterización de parámetros del intercambio gaseoso en la Ciudad de México / Characterization of gas exchange parameters in Mexico City

Introducción: en las grandes altitudes, el intercambio gaseoso suele estar deteriorado; en la altitud moderada de la Ciudad de México esto no está aún plenamente definido. Objetivo: caracterizar el intercambio gaseoso en la altitud moderada de la Ciudad de México. Material y métodos: mediante un estudio transversal analítico se estudiaron sujetos nacidos y habitantes de la Ciudad de México, de ambos géneros, con edades de 20 a 59 años sin enfermedad cardiopulmonar. Se registraron sus variables demográficas, espirometría simple y de gasometría arterial. Las diferencias en las variables se calcularon con ANOVA de una vía para grupos independientes y ajuste de Bonferroni. Una p < 0.05 se aceptó como significativa. Resultados: se estudiaron 335 sujetos, de los cuales 168 (50.15%) fueron hombres, la edad grupal fue de 45 ± 11 años, con índice de masa corporal 22.97 ± 1.54 Kg/m2. La relación volumen espiratorio forzado en el primer segundo/Capacidad vital forzada (VEF1/CVF) de 91.58 ± 12.86%. La presión arterial de oxígeno fue de 66 ± 5.02 mmHg, el bióxido de carbono: 32.07 ± 2.66 mmHg, la saturación arterial de oxígeno: 93.03 ± 1.80% y la hemoglobina: 14.07 ± 1.52 gr/dL. Conclusiones: la presión arterial de oxígeno y del bióxido de carbono están disminuidos a la altura de la Ciudad de México.

Background: At high altitude the gas exchange is impaired, in the moderate altitude of Mexico City they are not yet defined. Objective: To characterize the gas exchange in the moderate altitude of Mexico City. Material and methods: Through an analytical cross-sectional study, subjects born and inhabitants of Mexico City, both genders, aged 20 to 59 years without cardiopulmonary disease, were studied. Their demographic variables, simple spirometry and arterial blood gas were recorded. Differences in variables were calculated with one-way ANOVA for independent groups and Bonferroni adjustment. p < 0.05 was accepted as significant. Results: 335 subjects were studied, 168 (50.15%) men. Group age 45 ± 11 years old, body mass index 22.97 ± 1.54 Kg/m2. Forced expiratory volume ratio in the first second / Forced vital capacity (FEV1/FVC) 91.58 ± 12.86%. The arterial oxygen pressure was: 66 ± 5.02 mmHg, carbon dioxide: 32.07 ± 2.66 mmHg, arterial oxygen saturation: 93.0 3 ± 1.80%, and hemoglobin: 14.07 ± 1.52 gr/dL. Conclusions: The arterial oxygen pressure and carbon dioxide are lowered at the Mexico City altitude.

Adding autogenic drainage to chest physiotherapy after upper abdominal surgery: effect on blood gases and pulmonary complications prevention. Randomized controlled trial

ABSTRACT BACKGROUND: Hypoxemia and pulmonary complications are common after upper abdominal surgery (UAS). OBJECTIVE: To examine whether inclusion of autogenic drainage (AD) in chest physiotherapy after UAS confers additional benefits in improving blood gases and reducing postoperative pulmonary complications (PPCs). DESIGN AND SETTING: Randomized controlled study conducted at Kasr Al-Ainy teaching hospital, Egypt. METHODS: A randomized controlled trial was conducted on 48 subjects undergoing elective UAS with high risk of developing PPCs. The study group received AD plus routine chest physiotherapy (deep diaphragmatic breathing, localized breathing and splinted coughing) and the control group received routine chest physiotherapy only. The outcomes included arterial blood gases measured at the first and seventh postoperative days, incidence of PPCs within the first seven days and length of hospital stay. RESULTS: Baseline characteristics were similar between groups. In the AD group, SaO2, PaO2, PaCO2 and HCO3 significantly improved (P < 0.05) while in the physiotherapy group, only SaO2 and PaO2 significantly improved (P < 0.05). Nonetheless, significant differences in post-treatment SaO2 and PaO2 between the groups were observed. The overall incidence of PPCs was 16.66% (12.5% in the AD group and 20.8% in the physiotherapy group) (absolute risk reduction -8.3%; 95% confidence interval, CI, -13.5 to 29.6%), with no significant difference between the groups. The AD group had a significantly shorter hospital stay (P = 0.0001). CONCLUSION: Adding AD to routine chest physiotherapy after UAS provided a favorable blood gas outcome and reduced the length of hospital stay. It tended to reduce the incidence of PPCs. TRIAL REGISTRATION: ClinicalTrials.gov: NCT04446520.