Hemoglobina Denver, una causa de desaturación en oximetría de pulso. Reporte de caso en un paciente pediátrico / Hemoglobin Denver, a cause of desaturated pulse oximetry. A pediatric case report

Las hemoglobinopatías son trastornos genéticos que afectan a la molécula de hemoglobina (Hb). Las mutaciones en las cadenas a o b que alteran el tetrámero de Hb pueden modificar la capacidad de la molécula para unirse al oxígeno. Las hemoglobinopatías con baja afinidad al oxígeno pueden presentarse con cianosis y una lectura alterada de la oximetría de pulso, lo que lleva a pruebas innecesarias y, a veces, invasivas para descartar afecciones cardiovasculares y respiratorias. En el siguiente reporte de caso, presentamos a una paciente pediátrica, asintomática, que se presentó a la consulta por detección de desaturación en oximetría de pulso. Las pruebas de laboratorio iniciales mostraron una anemia normocítica, normocrómica. Las muestras de gas venoso demostraron una p50 elevada. Después de extensas herramientas de diagnóstico, se diagnosticó una variante de Hb con baja afinidad al oxígeno, Hb Denver.

Hemoglobinopathies are genetic disorders that affect the hemoglobin (Hb) molecule. Mutations in the alpha or beta chains altering the Hb tetramer may modify the molecule's oxygen-binding capacity. Hemoglobinopathies with low oxygen affinity may occur with cyanosis and an altered pulse oximetry reading, leading to unnecessary and sometimes invasive tests to rule out cardiovascular and respiratory conditions. In the case report described here, we present an asymptomatic pediatric patient who consulted for desaturated pulse oximetry. Her initial laboratory tests showed normocytic, normochromic anemia. Venous blood gas samples showed an elevated p50. After using extensive diagnostic tools, a variant of Hb with low oxygen affinity was diagnosed: Hb Denver.

Importance of assessing biomarkers and physiological parameters of anemia-induced tissue hypoxia in the perioperative period

Abstract Anemia is associated with increased risk of Acute Kidney Injury (AKI), stroke and mortality in perioperative patients. We sought to understand the mechanism(s) by assessing the integrative physiological responses to anemia (kidney, brain), the degrees of anemia-induced tissue hypoxia, and associated biomarkers and physiological parameters. Experimental measurements demonstrate a linear relationship between blood Oxygen Content (CaO2) and renal microvascular PO2 (y = 0.30x + 6.9, r2= 0.75), demonstrating that renal hypoxia is proportional to the degree of anemia. This defines the kidney as a potential oxygen sensor during anemia. Further evidence of renal oxygen sensing is demonstrated by proportional increase in serum Erythropoietin (EPO) during anemia (y = 93.806*10−0.02, r2= 0.82). This data implicates systemic EPO levels as a biomarker of anemia-induced renal tissue hypoxia. By contrast, cerebral Oxygen Delivery (DO2) is defended by a profound proportional increase in Cerebral Blood Flow (CBF), minimizing tissue hypoxia in the brain, until more severe levels of anemia occur. We hypothesize that the kidney experiences profound early anemia-induced tissue hypoxia which contributes to adaptive mechanisms to preserve cerebral perfusion. At severe levels of anemia, renal hypoxia intensifies, and cerebral hypoxia occurs, possibly contributing to the mechanism(s) of AKI and stroke when adaptive mechanisms to preserve organ perfusion are overwhelmed. Clinical methods to detect renal tissue hypoxia (an early warning signal) and cerebral hypoxia (a later consequence of severe anemia) may inform clinical practice and support the assessment of clinical biomarkers (i.e., EPO) and physiological parameters (i.e., urinary PO2) of anemia-induced tissue hypoxia. This information may direct targeted treatment strategies to prevent adverse outcomes associated with anemia.

Concentraciones de oxígeno intermitentes tienen impacto en el desarrollo postnatal temprano de ratas Sprague-Dawley: efectos en CA1 del hipocampo / Intermittent oxygen concentrations have an impact on the early postnatal development of Sprague-Dawley rats: effects on hippocampal CA1

El periodo postnatal temprano se caracteriza por rápido crecimiento cerebral, posiblemente relacionado con variaciones del oxígeno tisular. Esto ha motivado el estudio de protocolos que suministran diferentes concentraciones de oxígeno intermitentes, para observar sus efectos morfológicos y cerebrales. Se utilizaron 52 crías de ratas Sprague Dawley, distribuidas en igual número a cuatro grupos experimentales, Control (C, 21 %O2), Hipoxia Intermitente (HI, 11 %O2), Hiperoxia Intermitente (HOI, 30 %O2) e Hipoxia Hiperoxia Intermitente (HHI, 11 % -30 %O2). Los protocolos consideraron 5 ciclos de 5 minutos de dosificación, durante 50 minutos diarios. Se realizó en una cámara semihermética entre los días 5 al 11 postnatales. Las evaluaciones de crecimiento corporal y cuantificación neuronal, se realizaron en las crías macho, en el día 28 postnatal. El peso corporal en el grupo hipoxia intermitente mostró diferencias significativas respecto al grupo hiperoxia intermitente (HI vs HOI, p<0,01) y al grupo hipoxia-hiperoxia Intermitente (HI vs HHI, p< 0,001). La talla corporal disminuyó en el grupo hipoxia-hiperoxia intermitente con diferencias significativas respecto del grupo control (C vs HHI, p<0,05) y respecto del grupo hipoxia intermitente (HHI vs HI, p< 0,01). El conteo neuronal en el área CA1 del hipocampo aumentó en el grupo hipoxia intermitente con diferencias significativas respecto a los grupos control (C vs HI; p<0,05), al grupo hiperoxia intermitente (HI vs HOI; p<0,001) y al grupo hipoxia-hiperoxia intermitente (HI vs HHI; p<0,001). Finalmente, el grupo hipoxia- hiperoxia Intermitente disminuyó significativamente en la cantidad de neuronas en comparación al grupo hiperoxia intermitente (HHI vs HOI; p<0,001). La hipoxia intermitente mostró resultados beneficiosos en el crecimiento corporal y cantidad de neuronas en el área CA1 del hipocampo, en contraste, la hipoxia hiperoxia intermitente experimentó resultados adversos con disminución de estas variables, en el periodo postnatal temprano de la rata.

SUMMARY: The early postnatal period is characterized by rapid brain growth, possibly related to variations in tissue oxygen. This has motivated the study of protocols that supply different intermittent oxygen concentrations, to observe their morphological and cerebral effects. Fifty-two pups Sprague-Dawley rats were distributed in equal numbers into four experimental groups, Control (C, 21 %O), Intermittent Hypoxia (HI, 11 %O), Intermittent Hyperoxia (HOI, 30 %O2) and Intermittent Hypoxia Hyperoxia (HHI, 11 % - 30 %O2). The protocols considered 5 cycles of 5 min of dosing, for 50 min diary. It was performed in a semi- hermetic chamber between 5 to 11postnatal days. The evaluations of body growth and neuronal quantification were analyzed in male pups, on postnatal day 28. Body weight in the intermittent hypoxia group showed significant differences compared to the intermittent hyperoxia group (HI vs HOI, p<0.01) and the intermittent hypoxia- hyperoxia group (HI vs HHI, p<0.001). Body size decreased in the Intermittent hypoxia-hyperoxia group with significant differences compared to the control group (C vs HHI, p<0.05) and with respect to the intermittent hypoxia group (HHI vs HI, p<0.01). The neuronal count in the area CA1 of the hippocampus increased in the intermittent hypoxia group with significant differences compared to the control groups (C vs HI; p<0.05), to the intermittent hyperoxia group (HI vs HOI; p< 0.001) and the intermittent hypoxia-hyperoxia group (HI vs HHI; p<0.001). Finally, the intermittent hypoxia- hyperoxia group decreased significantly in the number of neurons compared with the intermittent hyperoxia group (HHI vs HOI; p<0.001). Intermittent hypoxia showed beneficial results in body growth and the number of neurons in the CA1 area of the hippocampus, in contrast, intermittent hypoxia-hyperoxia experienced adverse results with a decrease in these variables, in the early postnatal period of the rat.

Stoichioproteomics study of differentially expressed proteins and pathways in head and neck cancer / Estudo estequioproteômico de proteínas e vias expressas diferencialmente no câncer de cabeça e pescoço

Abstract Hypoxia is a prominent feature of head and neck cancer. However, the oxygen element characteristics of proteins and how they adapt to hypoxia microenvironments of head and neck cancer are still unknown. Human genome sequences and proteins expressed data of head and neck cancer were retrieved from pathology atlas of Human Protein Atlas project. Then compared the oxygen and carbon element contents between proteomes of head and neck cancer and normal oral mucosa-squamous epithelial cells, genome locations, pathways, and functional dissection associated with head and neck cancer were also studied. A total of 902 differentially expressed proteins were observed where the average oxygen content is higher than that of the lowly expressed proteins in head and neck cancer proteins. Further, the average oxygen content of the up regulated proteins was 2.54% higher than other. None of their coding genes were distributed on the Y chromosome. The up regulated proteins were enriched in endocytosis, apoptosis and regulation of actin cytoskeleton. The increased oxygen contents of the highly expressed and the up regulated proteins might be caused by frequent activity of cytoskeleton and adapted to the rapid growth and fast division of the head and neck cancer cells. The oxygen usage bias and key proteins may help us to understand the mechanisms behind head and neck cancer in targeted therapy, which lays a foundation for the application of stoichioproteomics in targeted therapy and provides promise for potential treatments for head and neck cancer.

Resumo A hipóxia é uma característica proeminente do câncer de cabeça e pescoço. No entanto, as características do elemento oxigênio das proteínas e como elas se adaptam aos microambientes de hipóxia do câncer de cabeça e pescoço ainda são desconhecidas. Sequências do genoma humano e dados expressos de proteínas de câncer de cabeça e pescoço foram recuperados do atlas de patologia do projeto Human Protein Atlas. Em seguida, comparou o conteúdo do elemento de oxigênio e carbono entre proteomas de câncer de cabeça e pescoço, e células epiteliais escamosas da mucosa oral normal, localizações do genoma, vias e dissecção funcional associada ao câncer de cabeça e pescoço também foram estudadas. Um total de 902 proteínas expressas diferencialmente foi observado onde o conteúdo médio de oxigênio é maior do que as proteínas expressas de forma humilde em proteínas de câncer de cabeça e pescoço. Além disso, o conteúdo médio de oxigênio das proteínas reguladas positivamente foi 2,54% maior do que das outras. Nenhum de seus genes codificadores foi distribuído no cromossomo Y. As proteínas reguladas positivamente foram enriquecidas em endocitose, apoptose e regulação do citoesqueleto de actina. O conteúdo aumentado de oxigênio das proteínas altamente expressas e reguladas pode ser causado pela atividade frequente do citoesqueleto e adaptado ao rápido crescimento e divisão das células cancerosas de cabeça e pescoço. O viés do uso de oxigênio e as proteínas-chave podem nos ajudar a entender os mecanismos por trás do câncer de cabeça e pescoço na terapia direcionada, o que estabelece uma base para a aplicação da estequioproteômica na terapia direcionada e oferece uma promessa para potenciais tratamentos para o câncer de cabeça e pescoço.

Approaches in the treatment of perianal fistula in Crohn disease

Perianal fistula is a common complication of Crohn disease, and it is a great burden on the life and psychology of patients, but its treatment is still a difficult problem to face. In recent years, progress in the treatment of Crohn disease has progressed rapidly due to the advent of biological agents, but there has been a lack of research on perianal fistula in Crohn disease, and the direction of research has been scattered; therefore, the author reviews the traditional treatment of perianal fistula in Crohn disease in the context of the available literature and discusses emerging and potential therapeutic approaches. (AU)

Ajuste de la relación o cociente PaO2 /Fio2 a la presión barométrica en la ciudad de La Paz 3600 msnm / Adjustment of the PaO2 /fio2 ratio or ratio to barometric pressure in the city of La Paz 3600 masl

La hipoxemia es común en los pacientes en estado crítico, la misma que puede ser causada por hipoventilación, trastornos en la ventilación/perfusión, los cortocircuitos de derecha-izquierda, o en la limitación de la difusión a través de la membrana alvéolo-capilar. Otra de las causas puede ser como resultado de las bajas presiones inspiradas de O2 como sucede en grandes alturas. La hipoxemia es uno de los parámetros importantes para la definición del síndrome de dificultad respiratoria aguda (SDRA). La relación PaO2/FiO2 se incluye en la definición de la conferencia del Consenso AmericanoEuropeo (lesión pulmonar aguda ≤ 300 y SIRA si es ≤ a 200). La hipoxia hipobárica es una manifestación que existe y que no se ha tomado en cuenta para la definición de LPA/SIRA. Cuando disminuye la presión barométrica (PB) como consecuencia de la disminución de la presión atmosférica (P atm), disminuye la presión parcial de oxígeno (PO2). Una de las formas para determinar la PaO2/FiO2 en relación a la presión barométrica es: PB ajustada: PAO2 x PaO2/FiO2/100, una fórmula similar a la publicada por West JB y utilizada en el estudio Alveoli: PaO2/FiO2 ajustada = PO2/FIO2 x (PB/760). La relación PO2/FIO2 debe ajustarse dependiendo de la presión barométrica.

Prone ventilation in intubated COVID-19 patients: a systematic review and meta-analysis

Abstract Background The efficacy and safety profiles of prone ventilation among intubated Coronavirus Disease 2019 (COVID-19) patients remain unclear. The primary objective was to examine the effect of prone ventilation on the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) in intubated COVID-19 patients. Methods Databases of MEDLINE, EMBASE and CENTRAL were systematically searched from inception until March 2021. Case reports and case series were excluded. Results Eleven studies (n = 606 patients) were eligible. Prone ventilation significantly improved PaO2/FiO2 ratio (studies: 8, n = 579, mean difference 46.75, 95% CI 33.35‒60.15, p < 0.00001; evidence: very low) and peripheral oxygen saturation (SpO2) (studies: 3, n = 432, mean difference 1.67, 95% CI 1.08‒2.26, p < 0.00001; evidence: ow), but not the arterial partial pressure of carbon dioxide (PaCO2) (studies: 5, n = 396, mean difference 2.45, 95% CI 2.39‒7.30, p= 0.32; evidence: very low), mortality rate (studies: 1, n = 215, Odds Ratio 0.66, 95% CI 0.32‒1.33, p= 0.24; evidence: very low), or number of patients discharged alive (studies: 1, n = 43, Odds Ratio 1.49, 95% CI 0.72‒3.08, p= 0.28; evidence: very low). Conclusion Prone ventilation improved PaO2/FiO2 ratio and SpO2 in intubated COVID-19 patients. Given the substantial heterogeneity and low level of evidence, more randomized- controlled trials are warranted to improve the certainty of evidence, and to examine the adverse events of prone ventilation.

Sulfohemoglobinemia secundaria a zopiclona. Casos clínicos / Sulfhemoglobinemia secondary to the use of zopiclone. Report of two cases

Sulfhemoglobin (SulfHb) is formed by hemoglobin (Hb) oxidation by sulfur compounds. Sulfhemoglobinemia is mainly associated with drugs or intestinal bacterial overgrowth. Patients present with central cyanosis, an abnormal pulse oximetry and normal arterial oxygen partial pressure. These features are shared with methemoglobinemia (MetHb) whose diagnosis requires an arterial co-oximetry. Depending on the device used, SulfHb may produce interference with this technique. We report two females aged 31 and 43 years, consulting at the emergency room with cyanosis. Both had a history of acute and chronic, high dose zopiclone ingestion. Pulse oximetry showed desaturation but with normal arterial oxygen partial pressure. Cardiac and pulmonary diseases were ruled out. Co-oximetry in two different analyzers showed interference or normal MetHb percentages. No other complications ensued, and cyanosis decreased over days. Since MetHb was discarded among other causes of cyanosis in a compatible clinical context, the diagnosis of sulfhemoglobinemia was made. The confirmatory method is not available in Chile. The presence of SulfHb is difficult to diagnose, confirmatory tests are not readily available, and it frequently interferes with arterial co-oximetry. This is attributed to a similar absorbance peak of both pigments in arterial blood. Venous co-oximetry can be useful in this context. SulfHb is a self-limited condition in most cases, however it must be differentiated from methemoglobinemia to avoid inappropriate treatments like methylene blue.

Efectos biológicos de la exposición a distintas concentraciones de oxígeno: desde la hipoxia hipobárica al oxígeno hiperbárico / Biological effects due to exposure to different concentrations of oxygen from hypo to hyperoxemia

The systemic effects of oxygen deficiency or excess are not thoroughly described. Knowledge is evolving towards the description of beneficial and detrimental effects of both extremes of partial pressure of oxygen (PaO2). The cellular and tissue mediators derived from the modulation of the oxidative tone and the production of reactive oxygen species (ROS) are widely characterized biochemically, but the pathophysiological characterization is lacking. Preclinical models support the use of hypobaric hypoxia preconditioning, based on its beneficial effects on ventricular function or its reduction in infarct size. A very important use of oxygen today is in commercial diving. However, novel clinical indications for oxygen such as the healing of diabetic foot ulcers and bone injury caused by radiotherapy are increasingly used. On the other hand, the modulation of the hypoxic response associated with exposure to high altitude environments (hypobaric), favors Chile and its highlands as a natural laboratory to determine certain cardiovascular, cerebral and metabolic responses in the resident population. Also, the consequences of the intermittent exposure to high altitudes in workers also deserves attention. This review discusses the physiopathological response to hypo and hyperoxemia, associated with environments with different oxygen concentrations, and brings back the concept of oxygen as a pharmacological mediator in extreme environments such as high altitudes and hyperbaric medicine in divers, decompression sickness, osteonecrosis associated with radiotherapy and sudden sensorineural hearing loss.

Effect of liberal or conservative oxygen therapy on the prognosis for mechanically ventilated intensive care unit patients: a meta-analysis

ABSTRACT BACKGROUND: For critically ill patients, physicians tend to administer sufficient or even excessive oxygen to maintain oxygen saturation at a high level. However, the credibility of the evidence for this practice is unclear. OBJECTIVE: To determine the effects of different oxygen therapy strategies on the outcomes of mechanically ventilated intensive care unit (ICU) patients. DESIGN AND SETTING: Systematic review of the literature and meta-analysis conducted at Jiangxi Provincial People's Hospital, Affiliated to Nanchang University, Nanchang, China. METHODS: We systematically searched electronic databases such as PubMed and Embase for relevant articles and performed meta-analyses on the effects of different oxygen therapy strategies on the outcomes of mechanically ventilated ICU patients. RESULTS: A total of 1802 patients from five studies were included. There were equal numbers of patients in the conservative and liberal groups (n = 910 in each group). There was no significant difference between the conservative and liberal groups with regard to 28-day mortality (risk ratio, RR = 0.88; 95% confidence interval, CI = 0.59-1.32; P = 0.55; I2 = 63%). Ninety-day mortality, infection rates, ICU length of stay, mechanical ventilation-free days up to day 28 and vasopressor-free days up to day 28 were comparable between the two strategies. CONCLUSIONS: It is not necessary to use liberal oxygen therapy strategies to pursue a higher level of peripheral oxygen saturation for mechanically ventilated ICU patients. Conservative oxygen therapy was not associated with any statistically significant reduction in mortality.

Carboxyhemoglobinemia as a laboratory finding in an outpatient

Resumen El monóxido de carbono (CO) es un gas producido principalmente por combustión incompleta de hidrocarburos. La intoxicación por exposición ambiental puede presentarse con síntomas inespecíficos y constituye la causa más importante de aumento de carboxihemoglobina (COHb). Su nivel en sangre depende de la duración de la exposición, la ventilación minuto y las concentraciones de CO y oxígeno en el ambiente. La elevada toxicidad radica en la hipoxia tisular que se genera. Se presenta el caso de un paciente masculino, 73 años, en seguimiento en el hospital por neumonía intersticial no específica como patología de base. En un control de laboratorio se encontró 11,9% de COHb, sin exposición a tabaco. No utilizaba calefacción a gas sino un panel cerámico eléctrico, recientemente pintado con esmalte sintético. La suspensión del uso del panel normalizó la COHb. El CO, producto de descomposición térmica del esmalte sintético, explica la causa de la intoxicación.

Abstract Carbon monoxide (CO) is a gas produced mainly by incomplete combustion of hydrocarbons. Poisoning from environmental exposure can present with nonspecific symptoms and is the most important cause of increased carboxyhemoglobin (COHb). Its blood level depends on the duration of exposure, minute ventilation, and the concentrations of CO and oxygen in the environment. The high toxicity lies in the tissue hypoxia that is generated. The case of a male patient, 73 years old, under follow-up in the hospital for non-specific interstitial pneumonia as the underlying pathology was presented. In a laboratory control, COHb 11,9% was found. There was no exposure to tobacco and there was no use of gas heating but of an electric ceramic panel, recently painted with synthetic enamel type paint. The suspension of the use of the panel normalised the COHb. The CO product of thermal decomposition of synthetic enamel explains the cause of poisoning.

Resumo O monóxido de carbono (CO) é um gás produzido principalmente pela combustão incompleta de hidrocarbonetos. A intoxicação por exposição ambiental pode se apresentar com sintomas inespecíficos e é a causa mais importante de aumento da carboxihemoglobina (COHb). Seu nível em sangue depende do tempo de exposição, da ventilação minuto e das concentrações de CO e oxigênio no ambiente. A alta toxicidade está na hipóxia tecidual gerada. Apresentamos o caso de um paciente do sexo masculino, 73 anos, em acompanhamento hospitalar por pneumonia intersticial inespecífica como patologia de bas. Em um controle laboratorial, achou-se 11,9% de COHb, sem exposição ao tabaco. Não utilizava aquecimento a gás e sim um painel elétrico cerâmico, recentemente pintado com esmalte sintético. A suspensão do uso do painel normalizou o COHb. O CO produto da decomposição térmica do esmalte sintético explica a causa da intoxicação.

Utilidad del monitoreo hemodinámico con espectroscopia cercana infrarroja en pediatría / Use of near infrared spectroscopy for hemodynamic monitoring in pediatrics

La espectroscopia cercana infrarroja (NIRS, por su sigla en inglés), es una técnica óptica no invasiva y no ionizante utilizada para medir la oxigenación tisular regional a través de sensores transcutáneos. En los últimos años, han aumentado de manera exponencial las publicaciones sobre este tema; esto refleja el creciente interés de investigadores y clínicos por la utilización de esta nueva tecnología y los beneficios que podría ofrecerles a los pacientes pediátricos. El objetivo de esta revisión es dar a conocer el funcionamiento y las posibles aplicaciones de la saturación regional medida por NIRS, así como los desafíos en el futuro.

Near infrared spectroscopy (NIRS) is a non-invasive optical technique for the evaluation of regional tissue oxygenation using transcutaneous detectors. In recent years, publications about this topic have increased exponentially; this reflects the growing interest among investigators and clinicians about this new technology and its potential benefits for pediatric patients. The objective of this review is to know the functioning and potential uses of regional saturation measured by NIRS and establish future challenges.

Oxygen use in Atacama large millimeter and submillimeter (ALMA) arrays in Chajnantor valley at 5050 m / Uso de oxígeno en Atacama large millimeter and submillimeter (ALMA) en el valle de Chajnantor a 5050 m

The Chilean workforce has over 200,000 people that are intermittently exposed to altitudes over 4000 m. In 2012, the Ministry of Health provided a technical guide for high altitude workers that included a series of actions to mitigate the effects of hypoxia. Previous studies have shown the positive effect of oxygen enrichment at high altitudes. The Atacama Large Millimeter / submillimeter Arrays (ALMA) radiotelescope operate at 5,050 m (Array Operation Site, AOS) and is the only place in the world where Pressure Swing Adsorption (PSA) and Liquid Oxygen technologies have been installed at a large scale. Here we discuss our experience using oxygen supplementation at ALMA, to prevent the malaise and/or risks associated with exposure at 5,050 m. Antenna operators experienced chronic intermittent hypobaric hypoxia (CIHH, shiftwork 8 days HA*6 days rest SL) over 4 years. Studies to define normal O2 saturation values were performed in OSF and AOS by continuous recording during the shift. The outcomes showed no differences between production procedures (PSA or Liquid oxygen) in regulating oxygen availability at AOS facilities. As a result, big-scale installations have difficulties reaching the appropriate oxygen concentration due to leaks in high mobility areas. In addition, the PSA plant requires adequation and maintenance to operate at a very high altitude.

La fuerza laboral chilena cuenta con más de 200.000 personas que están expuestas intermitentemente a altitudes superiores a los 4000 m. En 2012, el Ministerio de Salud entregó una guía técnica para trabajadores de altura que incluía una serie de acciones para mitigar los efectos de la hipoxia. Estudios anteriores han demostrado el efecto positivo del enriquecimiento de oxígeno en altitudes elevadas. El radiotelescopio Atacama Large Millimeter/submillimeter Arrays (ALMA) opera a 5.050 m (Array Operation Site, AOS) y es el único lugar en el mundo donde se han instalado tecnologías de adsorción por cambio de presión (PSA) y oxígeno líquido a gran escala. Aquí discutimos nuestra experiencia usando suplementos de oxígeno en ALMA, para prevenir el malestar y/o los riesgos asociados con la exposición a 5.050 m. Los operadores de antena experimentaron hipoxia hipobárica intermitente crónica (CIHH, trabajo por turnos 8 días HA*6 días descanso SL) durante 4 años. Se realizaron estudios para definir valores normales de saturación de O2 en OSF y AOS mediante registro continuo durante el turno. Los resultados no mostraron diferencias entre los procedimientos de producción (PSA u oxígeno líquido) en la regulación de la disponibilidad de oxígeno en las instalaciones de AOS. Como resultado, las instalaciones a gran escala tienen dificultades para alcanzar la concentración de oxígeno adecuada debido a fugas en áreas de alta movilidad. Además, la planta de PSA requiere de adecuación y mantenimiento para operar a gran altura.

Fisiología respiratoria: transporte de gases en sangre / Respiratory physiology: transport of oxygen and carbon dioxide in the blood

La sangre normalmente transporta pequeñas cantidades de oxígeno (O2) disuelto en el plasma y altas cantidades combinadas en forma química con la hemoglobina. La presión parcial depende solo del oxígeno disuelto físicamente, lo que determina cuánto oxígeno se combinará con hemoglobina. La curva de disociación de la hemoglobina describe la reversibilidad de la reacción entre oxígeno y hemoglobina. Los factores habituales que aumentan o disminuyen la afinidad de la hemoglobina por el oxígeno son el pH, presión parcial de CO2, temperatura y 2,3 difosfoglicerato. La sangre también transporta grandes cantidades en forma de bicarbonato y bajas cantidades de CO2 disuelto en plasma y combinado con proteínas como compuestos carbamino. La desoxihemoglobina favorece la formación de compuestos carbamínicos y promueve el transporte del CO2 como bicarbonato uniéndose al hidrógeno proveniente de la disociación del ácido carbónico. A continuación se describe en forma detallada los mecanismos fisiológicos del transporte de gases en sangre.

Blood normally carries small amounts of oxygen dissolved in plasma and large amounts chemically combined with hemoglobin. Partial pressure of oxygen depends only on physically dissolved oxygen which determines how much oxygen will combine with hemoglobin. The oxygen-hemoglobin dissociation curve (or oxyhemoglobin dissociation curve) describes the reversibility of the reaction between oxygen and hemoglobin. The usual factors that increase or decrease the affinity of hemoglobin for oxygen are pH, CO2 partial pressure, temperature, and 2,3 diphosphoglycerate. Blood also carries large amounts of CO2 as bicarbonate and low amounts dissolved in plasma and combined with proteins as carbamino compounds. Deoxyhemoglobin favors the formation of carbamino compounds and promotes the transport of CO2 as bicarbonate by joining the hydrogen from the dissociation of carbonic acid. The physiological mechanisms of gas transport in blood are described in detail below.

Effectiveness of supplemental oxygenation to prevent surgical site infections: A systematic review with meta-analysis / Efetividade da oxigenação suplementar para prevenção de infecção de sítio cirúrgico: revisão sistemática com metanálise / Efectividad de la oxigenación suplementaria para prevenir la infección del sitio quirúrgico: revisión sistemática con metaanálisis

Abstract Objective: to assess the effectiveness of supplemental oxygenation with high FiO2 when compared to conventional FiO2 in the prevention of surgical site infection. Method: an effectiveness systematic review with meta-analysis conducted in five international databases and portals. The research was guided by the following question: Which is the effectiveness of supplemental oxygenation with high FiO2 (greater than 80%) when compared to conventional FiO2 (from 30% to 35%) in the prevention of surgical site infections in adults? Results: fifteen randomized clinical trials were included. Although all the subgroups presented a general effect in favor of the intervention, colorectal surgeries had this relationship evidenced with statistical significance (I2=10%;X2=4.42; p=0.352). Conclusion: inspired oxygen fractions greater than 80% during the perioperative period in colorectal surgeries have proved to be effective to prevent surgical site infections, reducing their incidence by up to 27% (p=0.006). It is suggested to conduct new studies in groups of patients subjected to surgeries from other specialties, such as cardiac and vascular. PROSPERO registration No.: 178,453.

Resumo Objetivo: avaliar a efetividade da oxigenação suplementar com FiO2 elevada comparada com FiO2 convencional na prevenção de infecção de sítio cirúrgico. Método: revisão sistemática de efetividade com metanálise em cinco bases de dados e portais internacionais. A pesquisa foi norteada pela pergunta: Qual a efetividade da oxigenação suplementar com FiO2 elevada (maior que 80%) comparada com FiO2 convencional (de 30 a 35%) na prevenção de infecção de sítio cirúrgico em adultos? Resultados: foram incluídos quinze ensaios clínicos randomizados. Embora todos os subgrupos tenham apresentado um efeito geral a favor da intervenção, as cirurgias colorretais tiveram essa relação evidenciada com significância estatística (I2=10%; X2=4,42; p=0,352). Conclusão: uma fração inspirada de oxigênio maior que 80% durante o período perioperatório em cirurgias colorretais tem se mostrado efetiva para prevenir a infecção de sítio cirúrgico, reduzindo sua incidência em até 27% (p=0,006). Sugere-se a realização de novos estudos em grupos de pacientes submetidos a cirurgias de outras especialidades, tais como cardíacas e vasculares. Registro PROSPERO: 178453.

Resumen Objetivo: evaluar la efectividad de la oxigenación suplementaria con FiO2 elevada en comparación con la FiO2 convencional para prevenir la infección del sitio quirúrgico. Método: revisión sistemática de eficacia con metaanálisis en cinco bases de datos y portales internacionales. La investigación se guio por la pregunta: ¿Qué tan eficaz es la oxigenación suplementaria con FiO2 alta (más del 80%) en comparación con la FiO2 convencional (del 30 al 35%) para prevenir la infección del sitio quirúrgico en adultos? Resultados: se incluyeron quince ensayos clínicos aleatorizados. Aunque todos los subgrupos mostraron un efecto general a favor de la intervención, en las cirugías colorrectales esa relación tenía significancia estadística (I2=10%; X²=4,42; p=0,352). Conclusión: una fracción inspirada de oxígeno superior al 80% durante el perioperatorio en cirugías colorrectales ha demostrado ser eficaz en la prevención de la infección del sitio quirúrgico, reduciendo su incidencia hasta en un 27% (p=0,006). Se sugiere realizar más estudios en grupos de pacientes sometidos a cirugías en otras especialidades, como cardiaca y vascular. Registro PROSPERO: 178453.

¿El consumo máximo de oxígeno se relaciona con el rendimiento del WOD Pukie en sujetos físicamente activos? / Is maximal oxygen consumption related to Pukie WOD performance in physically active subjects?

Introducción: Las investigaciones sobre el entrenamiento funcional de alta intensidad son escasas a pesar de su popularidad. Objetivo: Establecer la asociación del consumo máximo de oxígeno y el rendimiento del WOD Pukie (150 burpees por tiempo) en sujetos físicamente activos. Metodología: Se realizó un estudio descriptivo-correlacional con enfoque cuantitativo de diseño no experimental y con una muestra no probabilística conformada por 14 hombres y 6 mujeres, las evaluaciones fueron realizadas en 2 días con una diferencia de 48 horas en las cuales el primer día se evaluó el consumo máximo de oxígeno a través del test de Course-Navette y el segundo día se aplicó el WOD Pukie, el análisis estadístico se aplicó en el IBM SPSS V.22 (Demo) (95% de confianza y un p-valor de 0,05) en el cual se aplicó la prueba de normalidad de Shapiro-Wilk, el coeficiente correlacional de Pearson (p > 0,05) y Spearman (p 0,05). Conclusión: En conclusión, el consumo máximo de oxigeno no es un predictor significativo del rendimiento en el WOD Pukie en sujetos físicamente activos(AU)

Introduction: Few studies have been conducted about high intensity functional training, despite the popularity of this form of exercise. Objective: Establish the association between maximal oxygen consumption and Pukie WOD performance (150 burpees per time unit) in physically active subjects. Methods: A non-experimental correlational-descriptive quantitative study was conducted of a nonprobability sample of 14 men and 6 women. The evaluations were performed in two days, with a separation of 48 hours between them. Maximal oxygen consumption was measured on the first day using the Course-Navette test, and the Pukie WOD was applied on the second day. Statistical analysis was performed with the software IBM SPSS V.22 (Demo) (95% confidence and a p-value of 0.05), the Shapiro-Wilk normality test, Pearson's chi-squared test (p > 0.05) and Spearman's correlation coefficient (p 0.05). Conclusion: Maximal oxygen consumption is not a significant predictor of Pukie WOD performance in physically active subjects(AU)

Central venous oxygen saturation/lactate ratio and prediction of major adverse events after pediatric heart surgery

Abstract Introduction: Major adverse events (MAE) are unexpected but undesirably frequent after pediatric congenital heart surgery and contribute to poorer outcomes. The aim of this study was to test the predictive value of a ratio between central venous oxygen saturation and arterial lactate (ScvO2/lactate) for MAE after pediatric congenital heart surgery in a Brazilian university hospital. Methods: We conducted a retrospective observational study in a tertiary care university hospital, including 194 infants and children submitted to surgery for congenital heart disease. The predictive value of ScvO2, lactate, and ScvO2/lactate ratio were assessed by the area under the receiver operating characteristics curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: The incidence of MAE was 16% — cardiac arrest/death, unplanned reoperation, and low cardiac output syndrome were the most common events. Overall, ScvO2/lactate ratio discriminated patients with and without MAE very well (AUC 0.842), performing better than either variable alone, with sensitivity of 48%, specificity of 94%, PPV of 60%, and NPV of 91%. Conclusion: A ScvO2/lactate ratio > 5 can accurately identify patients at low risk of MAE after pediatric congenital heart surgery, with very good specificity and NPV, but poor sensitivity and PPV.

Ventilación no invasiva versus oxigenoterapia convencional tras fracaso de la extubación en pacientes de alto riesgo en una unidad de cuidados intensivos: un ensayo clínico pragmático / Noninvasive ventilation versus conventional oxygen therapy after extubation failure in high-risk patients in an intensive care unit: a pragmatic clinical trial

RESUMEN Objetivo: Determinar la efectividad de la ventilación no invasiva frente a oxigenoterapia convencional en pacientes con insuficiencia respiratoria aguda tras fracaso de la extubación. Métodos: Ensayo clínico pragmático realizado una unidad de cuidados intensivos de marzo de 2009 a septiembre de 2016. Se incluyeron pacientes sometidos a ventilación mecánica > 24 horas, y que desarrollaron insuficiencia respiratoria aguda tras extubación programada, siendo asignados a ventilación no invasiva u oxigenoterapia convencional. El objetivo primario fue reducir la tasa de reintubación. Los objetivos secundarios fueron: mejora de los parámetros respiratorios, reducción de las complicaciones, de la duración de la ventilación mecánica, de la estancia en unidad de cuidados intensivos y hospitalaria, así como de la mortalidad en unidad de cuidados intensivos, hospitalaria y a los 90 días. También se analizaron los factores relacionados con la reintubación. Resultados: De un total de 2.574 pacientes, se analizaron 77 (38 en el grupo de ventilación no invasiva y 39 en el grupo de oxigenoterapia convencional). La ventilación no invasiva redujo la frecuencia respiratoria y cardíaca más rápidamente que la oxigenoterapia convencional. La reintubación fue menor en el grupo de ventilación no invasiva [12 (32%) versus 22(56%) en grupo oxigenoterapia convencional, RR 0,58 (IC95% 0,34 - 0,97), p = 0,039], el resto de los parámetros no mostró diferencias significativas. En el análisis multivariante, la ventilación no invasiva prevenía la reintubación [OR 0,17 (IC95% 0,05 - 0,56), p = 0,004], mientras que el fracaso hepático previo a la extubación y la incapacidad para mantener vía aérea permeable predisponían a la reintubación. Conclusión: El empleo de la ventilación no invasiva en pacientes que fracasa la extubación podría ser beneficiosa frente a la oxigenoterapia convencional.

ABSTRACT Objective: To determine the effectiveness of noninvasive ventilation versus conventional oxygen therapy in patients with acute respiratory failure after extubation failure. Methods: A pragmatic clinical trial was conducted in an intensive care unit from March 2009 to September 2016. Patients on mechanical ventilation > 24 hours who developed acute respiratory failure after scheduled extubation were included and were assigned to noninvasive ventilation or conventional oxygen therapy. The primary objective was to reduce the reintubation rate. The secondary objectives were to improve respiratory parameters and reduce complications, the duration of mechanical ventilation, the intensive care unit stay, the hospital stay, and mortality in the intensive care unit, in the hospital, and 90 days after discharge. Factors correlated with reintubation were also analyzed. Results: Of a total of 2,574 patients, 77 were analyzed (38 in the noninvasive ventilation group and 39 in the conventional oxygen therapy group). Noninvasive ventilation reduced the respiratory and cardiac rates more rapidly than conventional oxygen therapy. Reintubation was less common in the noninvasive ventilation group [12 (32%) versus 22 (56%) in the conventional oxygen therapy group, relative risk 0.58 (95%CI 0.34 - 0.97), p = 0.039]. The rest of the parameters did not show significant differences. In the multivariate analysis, noninvasive ventilation protected against reintubation [OR 0.17 (95%CI 0.05 - 0.56), p = 0.004], while liver failure before extubation and the inability to maintain airway patency predisposed patients to reintubation. Conclusion: The use of noninvasive ventilation in patients who failed extubation could be beneficial compared to conventional oxygen therapy.

Manejo de la hemorragia digestiva alta en pacientes con infección por SARS-CoV-2 en un hospital de Lima, Perú / Management of upper gastrointestinal bleeding in patients with SARS-COV-2 infection in a hospital in Lima-Peru

Resumen Introducción: la pandemia por SARS-CoV-2 ha conllevado la reestructuración de las unidades de endoscopía digestiva en el mundo, lo cual ha limitado los procedimientos endoscópicos y priorizado indicaciones de emergencia como la hemorragia digestiva alta (HDA). No obstante, existe escasa evidencia respecto a su impacto en la evolución y resultados. Objetivo: evaluar el manejo de la HDA en el contexto de la pandemia del coronavirus por SARS-CoV-2. Materiales y métodos: estudio observacional, descriptivo, retrospectivo de marzo a agosto de 2020 en pacientes con diagnóstico de HDA e infección por SARS-CoV-2. Resultados: de 4320 pacientes con infección por SARS-CoV-2, 51 presentaron HDA al ingreso. La mediana de edad fue de 70 años. El 58,8 % era de sexo masculino. El 56,9 % tenía una puntuación de Glasgow-Blatchford (SGB) ≥12. El 21,6 % requirió soporte de oxígeno. Solo 34 pacientes (66,7 %) recibieron tratamiento médico; asimismo, 17 (33,3 %) recibieron tratamiento médico más endoscopia digestiva alta (EDA); de estos, a 6 (35,3 %) se les realizó endoscopia terapéutica. La enfermedad ulcerosa péptica fue el hallazgo más frecuente. Al comparar el tipo de tratamiento recibido, no hubo diferencias significativas entre el número de transfusiones de glóbulos rojos, resangrado, reingreso por HDA, estancia hospitalaria ni mortalidad secundaria a la HDA. La mortalidad global fue del 25,4 % (13 pacientes) y se debió, principalmente, al compromiso respiratorio por SARS-CoV-2. Conclusiones: se observa una reducción en el número de EDA de emergencia por HDA en la pandemia actual, así como un tiempo mayor al estándar para su realización. Más del 80 % de los pacientes que recibieron solo tratamiento médico evolucionaron favorablemente, y solo un tercio de los pacientes a quienes se les realizó una EDA requirió terapéutica endoscópica.

Abstract Introduction: The SARS-CoV-2 pandemic has led to the restructuring of digestive endoscopy units around the world, limiting endoscopic procedures and prioritizing emergency indications such as upper gastrointestinal hemorrhage (UGH). However, there is little evidence regarding its impact on evolution and outcomes. Objective: To evaluate the management of UGH in the context of the SARS-CoV-2 coronavirus pandemic. Materials and methods: Observational, descriptive, retrospective study carried out between March and August 2020 in patients with diagnosis of UGH and SARS-CoV-2 infection. Results: Of 4 320 patients with SARS-CoV-2 infection, 51 had UGH on admission. The median age of the population was 70 years and 58.8% were male. Glasgow-Blatchford Bleeding Score (GBS) of ≥12 was obtained in 56.9%. Oxygen support was required by 21.6%. 34 (66.7%) patients received medical treatment only, while 17 (33.3%) received medical treatment plus upper gastrointestinal endoscopy (UGE), of which 6 (35.3%) underwent therapeutic endoscopy. Peptic ulcer disease was the most frequent finding. When comparing the type of treatment received, there were no significant differences between the number of red blood cell transfusions, rebleeding, re-admission due to UGH, hospital stay, or mortality secondary to UGH. Overall mortality was 25.4% (13 patients), mainly due to respiratory failure due to SARS-CoV-2. Conclusions: A reduction in the number of emergency upper gastrointestinal endoscopies for UGH was observed during the current pandemic, as well as a longer than standard time for their performance. More than 80% of patients who received medical treatment alone evolved favorably and only one third of the patients who underwent UGE required endoscopic therapy.

Glycemic safety of a maximum aerobic test in type 1 diabetics and their correlation with health parameters / Segurança glicêmica de um teste aeróbico máximo em pessoas com diabetes tipo 1 e sua correlação com parâmetros de saúde

To verify the glycemic safety of a maximal cardiorespiratory test (V̇ O2max) in T1DM patients and correlate the maximum cardiorespiratory values with metabolic control parameters such as glycemia, glycated hemoglobin, time of diagnosis (TD), and fat (body [GC] and visceral [GV]). The cross-sectional study evaluated ten T1DM patients (age 24.9 ± 7.5 years; time of diagnosis 11.5 ± 7.4; body mass index 22 ± 2 kg/m2 ). Metabolic glycemic control variables (before and after), glycated hemoglobin (HbA1c), time since diagnosis and total and visceral fat were collected. The CENESP maximum test protocol was used on the treadmill with direct maximal oxygen uptake (V̇ O2max). Normality test, paired t-test and correlations (p <0.05) were performed. In the results, blood glucose pre 189 ± 67 mg/dL vs. post 172 ± 66 mg/dL (p = 0.140). The V̇ O2max with a regular average score for men and women (37.4 ± 6.6 ml.kg.min-1). There was a negative and almost perfect correlation with TD, GC and GV (p = 0.028, p <0.000, and p <0.000). We conclude that is possible to perform a CENESP maximal with glycemic safe in T1DM. However, TD, GC, and GV negatively interfere with cardiorespiratory fitness and should be verified before the test. (AU)

Verificar a segurança glicêmica de um teste cardiorrespiratório máximo (V̇ O2max) em pacientes com diabetes mellitus tipo 1 (DM1) e correlacionar os valores com parâmetros de controle metabólico como glicemia, hemoglobina glicada, tempo de diagnóstico (DT) e gordura (corporal[GC] e visceral[GV]). O estudo transversal avaliou dez DM1 (idade 24,9 ± 7,5 anos; tempo de diagnóstico 11,5 ± 7,4; índice de massa corporal 22 ± 2 kg/m2). Foram coletadas variáveis de controle glicêmico metabólico (antes e depois), hemoglobina glicada (HbA1c), tempo de diagnóstico e gordura total e visceral. O protocolo de teste máximo do CENESP foi utilizado na esteira com consumo máximo direto de oxigênio (V̇ O2max). Teste de normalidade, teste t pareado e correlações (p<0,05) foram realizados. Nos resultados, glicemia pré 189 ± 67 mg/dL vs. pós 172 ± 66 mg/dL (p = 0,140). O V̇ O2max com pontuação média regular para homens e mulheres (37,4 ± 6,6 ml.kg.min-1). Houve correlação negativa e quase perfeita com DT, GC e GV (p = 0,028; p < 0,000 e p < 0,000). Concluímos que é possível realizar um CENESP máximo com segurança glicêmica no DM1. No entanto, DT, GC e GV interferem negativamente na aptidão cardiorrespiratória e devem ser verificados antes do teste.