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.

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

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.

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.

Correlation of End-Tidal Carbon Dioxide with Arterial Carbon Dioxide in Mechanically Ventilated Neonates: A Scoping Review.

Monitoring CO2 levels in intubated neonates is highly relevant in the face of complications associated with altered CO2 levels. Thus, this review aims to present the scientific evidence in the literature regarding the correlation between arterial carbon dioxide measured by non-invasive methods in newborns submitted to invasive mechanical ventilation. The search was carried out from January 2020 to January 2021, in the Scopus, Medline, The Cochrane Library, Web of Science, CINAHL and Embase databases. Also, a manual search of the references of included studies was performed. The main descriptors used were: "capnography," "premature infant," "blood gas analysis," and "mechanical ventilation." As a result, 221 articles were identified, and 18 were included in this review. A total of 789 newborns were evaluated, with gestational age between 22.8 and 42.2 weeks and birth weight between 332 and 4790 g. Capnometry was the most widely used non-invasive method. In general, the correlation and agreement between the methods evaluated in the studies were strong/high. The birth weight did not influence the results. The gestational age of fewer than 37 weeks implied, in its majority, a moderate correlation and agreement. Therefore, we can conclude that there was a predominance of a strong correlation between arterial blood gases and non-invasive methods, although there are variations found in the literature. Even so, the results were promising and may provide valuable data for future studies, which are necessary to consolidate non-invasive methods as a reliable and viable alternative to arterial blood gasometry.

Noninvasive hemoglobin monitoring in clinical trials: a systematic review and meta-analysis / Monitorização não invasiva da hemoglobina em ensaios clínicos: uma revisão sistemática e metanálise

Abstract Background and objectives: The measurement of hemoglobin concentration (Hb) by co-oximetry is an innovative technique that offers efficiency and agility in the processing of information regarding the measurement of Hb obtained through continuous, non-invasive and rapid monitoring. Because of this attribute, it avoids unnecessary exposures of the patient to invasive procedures by allowing a reduction in the number of blood samples for evaluation and other unnecessary therapies. It also helps to make decisions about the need for transfusion and how to handle it. The objective of this study is to compare the performance offered to obtain Hb values between the Masimo Corporation (Irvine, CA, USA) instrument and the standard gold tool (laboratory examination). Contents: The study corresponds to a systematic review followed by meta-analysis, which included fully registered full-text clinical trials published from 1990 to 2018. PubMed, Cochrane, Medline, Embase and Web of Science databases were investigated. The mean overall difference found between the non-invasive and invasive methods of hemoglobin monitoring was 0.23 (95% CI -0.16, 0.62), that is, it did not present statistical significance (p = 0.250). The results of the analysis of heterogeneity within and between the studies indicated high levels of inconsistency (Q = 461.63, p < 0.0001, I2 = 98%), method for Hb values. Conclusions: Although the mean difference between noninvasive measurements of Hb and the gold standard method is small, the co-oximeter can be used as a non-invasive "trend" monitor in detecting unexpected responses at Hb levels.

Resumo Justificativa: A medida da concentração de hemoglobina (Hb)por co-oximetria é uma técnica inovadora que oferece eficiência e agilidade no processamento das informações referentes à medida da concentração de hemoglobina obtida por meio de monitorização contínua, não-invasiva e rápida. Por conta desse atributo, evita exposições desnecessárias do paciente a procedimentos invasivos ao possibilitar redução da quantidade de amostras sanguíneas para avaliação e de outras terapêuticas desnecessárias. Além disso, auxilia a tomada de decisões quanto à necessidade de transfusão e quanto ao manejo da mesma. Objetivo: Comparar o desempenho oferecido para a obtenção dos valores de concentração de hemoglobina entre medida não invasiva da Hb e a ferramenta padrão ouro (exame laboratorial). Conteúdo: O estudo corresponde a uma revisão sistemática seguida de metanálise que incluiu ensaios clínicos devidamente registrados com texto completo, publicados a partir de 1990 até 2018. Foram investigadas as bases de dados PubMed, Cochrane, Medline, Embase e Web Of Science. A diferença média global encontrada entre os métodos não invasivo e invasivo de monitorização da hemoglobina foi de 0,23 (95% IC -0,16; 0,62), ou seja, não apresentou significância estatística (p = 0,250). Os resultados da análise de heterogeneidade dentro e entre os estudos, apontou níveis elevados de inconsistência (Q = 461,63, p< 0,0001, I2 = 98%). Conclusão: Embora a diferença média entre as medidas não invasivas da Hb e o método padrão ouro sejam pequenas, o co-oxímetro pode ser utilizado como um monitor não invasivo de "tendência" na detecção de alterações inesperadas nos níveis de Hb.

[Noninvasive hemoglobin monitoring in clinical trials: a systematic review and meta-analysis]. / Monitorização não invasiva da hemoglobina em ensaios clínicos: uma revisão sistemática e metanálise.

BACKGROUND AND OBJECTIVES: The measurement of Hb by co-oximetry is an innovative technique that offers efficiency and agility in the processing of information regarding the measurement of Hemoglobin concentration (Hb) obtained through continuous, non-invasive and rapid monitoring. Because of this attribute, it avoids unnecessary exposures of the patient to invasive procedures by allowing a reduction in the number of blood samples for evaluation and other unnecessary therapies. It also helps to make decisions about the need for transfusion and how to handle it. The objective of this study is to compare the performance offered to obtain Hb values between the Masimo Corporation (Irvine, CA, USA) instrument and the standard gold tool (laboratory examination). CONTENTS: The study corresponds to a systematic review followed by meta-analysis, which included fully registered full-text clinical trials published from 1990 to 2018. PubMed, Cochrane, Medline, Embase and Web of Science databases were investigated. The mean overall difference found between the non-invasive and invasive methods of hemoglobin monitoring was 0.23 (95% CI -0.16, 0.62), that is, it did not present statistical significance (p = 0.250). The results of the analysis of heterogeneity within and between the studies indicated high levels of inconsistency (Q = 461.63, p < 0.0001, I2 = 98%), method for Hb values. CONCLUSIONS: Although the mean difference between noninvasive measurements of Hb and the gold standard method is small, the co-oximeter can be used as a non-invasive "trend" monitor in detecting unexpected responses at Hb levels.

Análisis de diversas variables polisomnográficas y su relación con la severidad del síndrome de apnea e hipoapnea obstructiva del sueño / The analysis of polysomnographic variables and their relation with severity of obstructive sleep apnea and hypopnea syndrome

genera obstrucción de la vía aérea superior, y el estándar de oro para su diagnóstico es la polisomnografía (PSG). Objetivo: esclarecer la relación que existe entre las variables polisomnográficas y la severidad de la enfermedad, para tener más elementos objetivos al determinar el manejo y el seguimiento médico. Diseño: estudio observacional analítico de corte transversal. Metodología: se analizaron las variables polisomnográficas de 575 pacientes mediante el software STATA® VE 15.0; con la prueba Kruskal Wallis se evaluó la relación entre estas y la severidad. Resultados: la prevalencia de SAHOS en la cohorte fue de 73,04 %; a mayor duración media de apnea MAD se encontraron peores datos de SaO2. La media de Ct90 en pacientes sanos fue 2,55 %. La MAD en pacientes con SAHOS moderado y severo fue de 21 segundos, mientras que el REM IAH, el Ct90 y la duración máxima de apneas tuvieron buena relación con el IAH. Conclusiones: los microdespertares, el Ct90, la SaO2 mínima, la MAD y la frecuencia cardíaca máxima están relacionados de manera importante con la severidad de la enfermedad. El WASO, la duración mínima de apneas, la vigilia antes del sueño y la frecuencia cardíaca mínima no están relacionados. Las apneas de larga duración por encima de 18,5 segundos se asociaron significativamente a peores cifras de oxigenación. Los números de microdespertares tienen una relación fuerte con la severidad de la enfermedad y la más fuerte con los datos de peor oxigenación.

Introduction: The obstructive sleep apnea/Hypopnea syndrome (OSAHS) generates obstruction of the upper air way and the gold standard for its diagnosis is the polysomnography. Objective: To clarify the relation between the polysomnographic variables and the severity of the condition in order to have more objective elements to help choose the best management and medical follow up. Design: Cross-Sectional, analytical and observational study. Methodology: The polysomnographic variables of 575 patients were analyzed using STATA® VE 15.0 software. The relation between the variables and their severity were evaluated using the Kruskall Wallis Test. Results: The prevalence of the (OSAHS) in the cohort was 73.04 %, to longer MADs lowest SaO2 data, the media of Ct90 in healthy patients was 2.55 %. The media MAD for patients with moderate and severe OSA was 21 seconds. The REM IAH, Ct90 and maximum duration of apnea had a strong relation with the IAH. Conclusions: The arousals, the Ct90, the lowest SaO2, the MAD and the maximum cardiac frequency are crucially related to the severity of the condition. The WASO, the minimum duration of the apneas, the vigil before sleep and the minimum cardiac frequency are not related. The apneas with the longest duration, above 18.5 seconds, are significantly associated with the worst numbers of oxygenation. The number of arousals is strongly linked to the severity of the disease being the most severe related to the data associated with the worst oxygenation.

Presión intraabdominal y ventilación artificial mecánica. Hospital "Arnaldo Milián Castro". 2014-2015 / Intra-abdominal pressure and mechanical artificial ventilation. Arnaldo Milián Castro Hospital. 2014-2015

Introducción: La cavidad abdominal y la caja torácica se encuentran separadas por el diafragma, por lo que las variaciones en las presiones dentro de una, repercuten sobre las presiones de la otra. La hipertensión intraabdominal es hoy una entidad frecuente en el paciente crítico en el que constituye un factor de riesgo importante de complicaciones y mortalidad, ya que influye sobre órganos y sistemas. Objetivo: Relacionar la presión intraabdominal con presiones de la ventilación artificial mecánica y parámetros de la función respiratoria, cardiovascular y renal. Material y Métodos: Se realizó un estudio descriptivo y prospectivo de la presión intraabdominal en pacientes sometidos a ventilación mecánica, con enfermedades clínicas y quirúrgicas, en las Unidades de Cuidados Intensivos del Hospital Clínico Quirúrgico Arnaldo Milán Castro, durante el período comprendido entre enero 2014 hasta diciembre 2015. Resultados: Los pacientes clínicos con presiones de la vía aérea elevadas mostraron valores más altos de presión intraabdominal, y aquellos pacientes postquirúrgicos que cursaron con niveles altos de presión dentro del abdomen también presentaron los valores más elevados de presión pico y media registradas en el ventilador mecánico. Conclusiones: La tensión arterial media, el ritmo diurético y la saturación periférica de oxígeno disminuyeron, mientras que la presión venosa central, la presión parcial de dióxido de carbono en sangre y la creatinina aumentó ante los aumentos de la presión dentro del abdomen(AU)

Introduction: The abdominal cavity and the thoracic cage are separated by the diaphragm; therefore, the variations in the pressures within one of them have an effect on the pressures of the other. At present, intra-abdominal hypertension is a frequent entity in the critically ill patient, which constitutes an important risk factor for complications and mortality since it influences on different organs and systems. Objective: To relate intra-abdominal pressure with mechanical artificial ventilation pressures and parameters of respiratory, cardiovascular and renal function. Material and Methods: A descriptive prospective study of intra-abdominal pressure was conducted in patients undergoing mechanical ventilation with clinical and surgical diseases in the Intensive Care Units of the Arnaldo Milán Castro Hospital, during the period between January 2014 until December 2015. Results: Clinical patients with high values of airway pressures showed higher values of intra-abdominal pressure, and those post-surgical patients who presented with high levels of pressure inside the abdomen indicated the highest values of peak and average pressure recorded in the mechanical ventilator. Conclusions: Mean arterial pressure, diuretic rate and peripheral oxygen saturation decreased, whereas the central venous pressure, the partial pressure of carbon dioxide in blood, and creatinine increased due to raises in pressure within the abdomen(AU)

Effect of Transcutaneous Electrode Temperature on Accuracy and Precision of Carbon Dioxide and Oxygen Measurements in the Preterm Infants.

BACKGROUND: High electrode temperature during transcutaneous monitoring is associated with skin burns in extremely premature infants. We evaluated the accuracy and precision of CO2 and O2 measurements using lower transcutaneous electrode temperatures below 42°C. METHODS: We enrolled 20 neonates. Two transcutaneous monitors were placed simultaneously on each neonate, with one electrode maintained at 42°C and the other randomized to temperatures of 38, 39, 40, 41, and 42°C. Arterial blood was collected twice at each temperature. RESULTS: At the time of arterial blood sampling, values for transcutaneously measured partial pressure of CO2 (PtcCO2 ) were not significantly different among test temperatures. There was no evidence of skin burning at any temperature. For PtcCO2 , Bland-Altman analyses of all test temperatures versus 42°C showed good precision and low bias. Transcutaneously measured partial pressure of O2 (PtcO2 ) values trended arterial values but had large negative bias. CONCLUSION: Transcutaneous electrode temperatures as low as 38°C allow an assessment of PtcCO2 as accurate as that with electrodes at 42°C.

24-Hour Hypoxia and Pulmonary Hypertension in Patients with Idiopathic Pulmonary Fibrosis.

BACKGROUND: The quantification of hypoxia based on resting partial pressure of arterial oxygen (PaO2) may underestimate hypoxia related to activities of daily living or sleep and thus not accurately reflect pulmonary hypertension (PH). The aim of the present study was to investigate the association of resting PaO2 with percent time of SpO2 below 90% (T90) and 88% (T88) in 24 hours. We also evaluated the capacity of hypoxia measures to predict PH in patients with idiopathic pulmonary fibrosis (IPF). METHOD: This cross-sectional study included 27 patients with IPF presenting PaO2 ≥ 55 mmHg and not receiving home oxygen therapy. All were submitted to blood gas measurement, 24-h oximetry, and transthoracic Doppler echocardiography to estimate systolic pulmonary artery pressure (SPAP). Patients were divided into three groups according to resting PaO2: 55-55.9 mmHg (A); 60-60.9 mmHg (B); ≥ 70 mmHg (C). PH was defined as "likely" if SPAP > 50 mmHg, and as possible for SPAP between 37 and 50 mmHg. RESULTS: T90 and T88 in Groups A, B, and C were as follows: 59.9±29% and 44.1±34%; 49.3±34% and 29.9±31%; 17.1±25% and 8.8±18% respectively, with significant differences between the groups for both T90 (p ≤ 0.01) and T88 (p = 0.02). PaO2 was inversely correlated with T90 (r = -0.398; p = 0.04) and T88 (r = -0.351; p = 0.07). Hypoxia variables did not correlate with SPAP, and were not able to predict PH. CONCLUSION: Percent time of SpO2 below 90% and 88% in 24 hours revealed periods of severe hypoxia even in patients with borderline-normal resting PaO2. However, none of the present hypoxia variables was capable of predicting PH.

Pulsioximetría en la prueba marcha de seis minutos como predictor de alteración funcional respiratoria en trabajadores de minería artesanal del carbón / Pulse oximetry in six minutes walking test as a predictor of functional respiratory alteration in workers at artisanal coal mining

Objetivo: Evaluar prospectivamente y mediante comparación, durante la prueba de marcha de 6 minutos, el comportamiento de la saturación arterial de oxígeno (SPO2) y otras variables vitales, en dos grupos, uno de mineros del carbón (expuestos) y otro de trabajadores universitarios (controles). Materiales y métodos:Estudio prospectivo de cohortes. Se realizó la prueba (PM6M) en 72 trabajadores mineros y 46 trabajadores universitarios. Se midió minuto a minuto SPO2, frecuencia cardiaca y distancia recorrida. Resultados: Se encontró una significativa desaturación de oxígeno, ante un ejercicio moderado, en los trabajadores mineros, equivalente a una manifestación precoz de alteración funcional del intercambio alveolo-capilar. Conclusiones: La exposición respiratoria sostenida a polvo de carbón y sílice podría ocasionar alteración funcional del intercambio gaseoso alveolo capilar. La pulsioximetría en la prueba de marcha de 6 minutos se perfila como una herramienta útil y costo-efectiva en salud ocupacional para el seguimiento y control de la salud de los mineros del carbón.

Objective: To evaluate prospectively and through comparison the behavior of the arterial oxygen saturation (SPO2) and other vital variables in two groups, one of coal miners (exposed) and another formed by university workers (controls) during the test run of 6 minutes. Materials and methods: Prospective cohort study. The test (6MWT) was performed in 72 miners and 46 university workers. SpO2, heart rate and walked distance were estimated every minute. Results: A significant oxygen desaturation was found in the mineworkers when practicing a moderate exercise, which is equivalent to an early manifestation of functional impairment of the alveolar-capillary exchange. Conclusions: The sustained respiratory exposure to coal dust and silica may cause functional impairment of alveolar capillary gas exchange. The pulse oximetry in the 6 minutes walking test is emerging as a useful and cost-effective occupational health tool to monitor and health surveillance of coal miners.

Oxygen desaturation during the six-minute walk test in COPD patients / Análise da dessaturação de oxigênio durante o teste de caminhada de seis minutos em pacientes com DPOC

Objective: To evaluate the behavior of oxygen saturation curves throughout the six-minute walk test (6MWT) in patients with COPD. Methods: We included 85 patients, all of whom underwent spirometry and were classified as having moderate COPD (modCOPD, n = 30) or severe COPD (sevCOPD, n = 55). All of the patients performed a 6MWT, in a 27-m corridor with continuous SpO2 and HR monitoring by telemetry. We studied the SpO2 curves in order to determine the time to a 4% decrease in SpO2, the time to the minimum SpO2 (Tmin), and the post-6MWT time to return to the initial SpO2, the last designated recovery time (RT). For each of those curves, we calculated the slope. Results: The mean age in the modCOPD and sevCOPD groups was 66 ± 10 years and 62 ± 11 years, respectively. At baseline, SpO2 was > 94% in all of the patients; none received supplemental oxygen during the 6MWT; and none of the tests were interrupted. The six-minute walk distance did not differ significantly between the groups. The SpO2 values were lowest in the sevCOPD group. There was no difference between the groups regarding RT. In 71% and 63% of the sevCOPD and modCOPD group patients, respectively, a ≥ 4% decrease in SpO2 occurred within the first minute. We found that FEV1% correlated significantly with the ΔSpO2 (r = −0.398; p < 0.001), Tmin (r = −0.449; p < 0.001), and minimum SpO2 (r = 0.356; p < 0.005). Conclusions: In the sevCOPD group, in comparison with the modCOPD group, SpO2 was lower and the Tmin was greater, suggesting a worse prognosis in the former. .

Objetivo: Avaliar o comportamento da curva de saturação de oxigênio durante o teste de caminhada de seis minutos (TC6) em pacientes com DPOC. Métodos: Incluímos 85 pacientes e todos realizaram espirometria, sendo classificados como portadores de DPOC moderada (DPOCm, n = 30) ou grave (DPOCg, n = 55). Todos os pacientes realizaram TC6 em um corredor de 27 m com monitoramento contínuo da SpO2 e FC por telemetria. A partir das curvas de SpO2, foram analisados os tempos para atingir a queda de 4% da SpO2, para atingir a SpO2 mínima (Tmin) e para a recuperação da SpO2 após o TC6 (TR). Foram calculadas as inclinações dessas curvas. Resultados: A média de idade nos grupos DPOCm e DPOCg foi de 62 ± 11 anos e 66 ± 10 anos, respectivamente. Todos os pacientes iniciaram o teste com SpO2 > 94%, nenhum recebeu suplementação de oxigênio durante o TC6, e não houve interrupções. A distância percorrida no TC6 não apresentou diferença significativa entre os grupos. Os menores valores da SpO2 ocorreram no grupo DPOCg. Não houve diferença no TR entre os grupos, e 71% e 63% dos pacientes nos grupos DPOCg e DPOCm, respectivamente, apresentaram queda de SpO2 ≥ 4% até o primeiro minuto. O VEF1% apresentou correlações significativas com ΔSpO2 (r = −0,398; p < 0,001), Tmin (r = −0,449; p < 0,001) e SpO2 mínima (r = 0,356; p < 0,005). Conclusões: As curvas dos pacientes do grupo DPOCg em relação às do grupo DPOCm apresentaram valores menores de SpO2 e maior Tmin, sugerindo um pior prognóstico nos primeiros. .

Diferencia veno-arterial de dióxido de carbono como predictor de gasto cardiaco disminuido en modelo pediátrico experimental / Veno-arterial difference of carbondioxide as a predictor of low cardiac output in an experimental pediatric model

Background: Cardiac output (CO) measurement is not a standard of care for critically ill children, but it can be estimated by indirect methods such as veno-arterial pCO2 difference (ΔVACO2). Aim: To determine the correlation between CO and ΔVACO2 and evaluate the usefulness of ΔVACO2 in the diagnosis of low CO in an experimental pediatric model. Materials and Methods: Thirty piglets weighing 4.8 ± 0.35 kg were anesthetized and monitored with transpulmonary thermodilution. Lung injury was induced with tracheal instillation of Tween 20®. Serial measurements of central venous and arterial blood gases, as well as CO, were obtained at baseline, 1, 2 and 4 h after lung injury induction. Low cardiac output (LCO) was defined as CO lower than 2.5 Llminlm². Results: There was an inverse correlation between CO and ΔVACO2 (r = -0.36, p < 0.01). ΔVACO2 was 14 ± 8 mmHg in LCO state and 8 ± 6 mmHg when this condition was not present (p < 0.01). Area under the receiver operating characteristic (ROC) curves of ΔVACO2 and LCO state was 0.78 (0.68-0.86). The best cut-point was 8.9 mmHg to determine LCO with a sensibility 0.78, specificity 0.7, positive predictive value 0.27 and negative predictive value 0.96. Conclusions: In this model there was an inverse correlation between ΔVACO2 and CO. The best cutoff value to discard LCO was ΔVACO2 of 8.9 mmHg, indicating that under this value the presence of LCO is very unlikely.