Oxygen Debt as Predictor of Mortality and Multiple Organ Dysfunction Syndrome in Severe COVID-19 Patients: A Retrospective Study.

Background: Oxygen debt (DEOx) represents the disparity between resting and shock oxygen consumption (VO2) and is associated with metabolic insufficiency, acidosis, severity, and mortality. This study aimed to assess the reliability of DEOx as an indirect quantitative measure for predicting multiple organ dysfunction syndrome (MODS) and 28-day mortality in patients admitted to the intensive care unit (ICU) with respiratory syndrome severe acute coronavirus type 2 (SARS-CoV-2) infection, in comparison to the Acute Physiology and Chronic Health Evaluation II (APACHE II), sepsis-related organ failure assessment (SOFA), and 4C scores. Methods: A retrospective cohort study was conducted, including ICU patients with SARS-CoV-2 infection between 2020 and 2021. Clinical data were extracted from the EPIMED Monitor Database®. APACHE II, SOFA, and 4C scores were calculated upon ICU admission, and their accuracy in predicting 28-day mortality and MODS was compared to DEOx. Multivariate logistic regression analysis was performed to analyze the outcome variables. Results: 708 patients were included, with a mortality rate of 44.4%. DEOx value was 11.16 ml O2/kg. The mean age was 58.7 years. Multivariate analysis showed that DEOx was independently associated with mortality, intubation, and renal injury. Each point increase in creatinine was associated with a higher risk of MODS. To determine the precision of the scores, area under the receiver operating characteristic curves (AUROC) analysis was performed with weak discrimination and similar behavior for the primary outcomes. The most accurate scale for mortality and MODS was 4C with an AUC of 0.683 and APACHE II with an AUC of 0.814, while that of the AUROC of DEOx was 0.612 and 0.646, respectively. Conclusions: DEOx showed similar predictive value to established scoring systems in critically ill patients with SARS-CoV-2 infection. The correlation of DEOx with these scores may facilitate early intervention in critically ill patients.

La importancia de la determinación de la deuda de oxígeno en el perioperatorio / The importance of oxygen debt determination in the perioperative period

Resumen: El fenómeno de la deuda de oxígeno (dO2) descrito hace varias décadas en el contexto del ejercicio físico se ha incorporado progresivamente al terreno de la medicina. En particular se ha utilizado durante los cambios hemodinámicos producidos por la cirugía y la anestesia en los pacientes de alto riesgo. La dO2 se definió como el aumento en la cantidad de oxígeno consumida por el organismo inmediatamente después de realizar un ejercicio físico hasta que el consumo se normaliza nuevamente. En el perioperatorio se llega a producir cuando se presenta un desbalance entre la oferta (DO2) y la demanda de oxígeno (VO2) que lleva a hipoxia tisular. El grado de la dO2 tisular se ha relacionado directamente con la falla de órganos múltiples y morbimortalidad perioperatoria. A pesar de los avances en la medicina, aún no es posible prevenir o disminuir la dO2 con la administración de líquidos o con el uso de agentes vasoactivos. Por lo que un retardo o manejo inadecuado de la hemodinámica perioperatoria producirá hipoperfusión e hipoxia tisular afectando los resultados de la cirugía. El conocimiento y la valoración de la dO2 es esencial durante la anestesia del paciente de alto riesgo. Para lograr este objetivo se requiere del uso de índices adecuados que permitan detectar y cuantificar la hipoperfusión tisular y el desbalance entre la DO2 y la VO2. En esta revisión se presentan los conceptos fundamentales de la dO2, su mecanismo, detección y cuantificación; además de las intervenciones para evitarla o disminuirla y las recomendaciones para los anestesiólogos con el fin de asegurar mejores resultados en los pacientes quirúrgicos de alto riesgo.

Abstract: The phenomenon of oxygen debt (dO2) described several decades ago in the context of physical exercise has been incorporated into medicine, particularly during the hemodynamic changes produced by surgery and anesthesia in high-risk patients. dO2 is defined as the increase in the amount of oxygen consumed by the body immediately after physical exercise until O2 consumption returns to normal. In the perioperative period, an imbalance between oxygen supply (DO2) and demand (VO2) could generate dO2. The degree of tissue dO2 has been directly related to multiple organ failure and perioperative morbimortality. Despite advances in medicine, it is not yet possible to prevent or lower the dO2 with fluid administration or vasoactive agents. Delay or inadequate management of hemodynamics could produce tissue hypoperfusion and hypoxia, affecting surgery outcomes. Knowledge and assessing dO2 during perioperative are essential during anesthesia for high-risk patients. Adequate indices are required to detect and quantify tissue hypoperfusion and the imbalance between DO2 and VO2 during anesthesia. This review presents the mechanism, detection, and quantification of dO2. In addition to interventions to avoid or reduce dO2 and recommendations for anesthesiologists to ensure better results in high-risk surgical patients.

Determinação visual do componente rápido do excesso do consumo de oxigênio após o exercício / Visual determination of the fast component of excessive oxygen uptake after exercise

O objetivo do presente estudo foi analisar a validade, a reprodutibilidade e a objetividade do método de inspeção visual durante a identificação da fase rápida do excesso do consumo de oxigênio após o exercício (EPOC RÁPIDO). Dez homens fisicamente ativos (idade de 23,0 ± 4,0 anos, estatura de 176,4 ± 6,8cm, massa corporal de 72,4 ± 8,2kg, VòO2max 3,0 ± 0,5L ? min-1) realizaram um teste incremental máximo e um teste de carga constante até a exaustão a 110 por cento da carga máxima obtida no teste incremental. O consumo de oxigênio foi mensurado respiração a respiração durante dez minutos de recuperação passiva após o teste de carga constante. O EPOC RÁPIDO foi determinado matematicamente e visualmente por três avaliadores. O método visual foi aplicado duas vezes nos três avaliadores para verificar a sua reprodutibilidade. Não foram detectadas diferenças significativas entre os valores do EPOC RÁPIDO estabelecidos pelo método matemático (0,98 ± 0,45L) e pelo método visual identificado pelos três avaliadores (1,04 ± 0,45L, 1,02 ± 0,45L e1,02 ± 0,45L). Nenhuma diferença foi encontrada entre a primeira e a segunda identificação feita pelos avaliadores (avaliador 1: 1,04 ± 0,45L vs 1,04 ± 0,49L; avaliador 2: 1,02 ± 0,45L vs 1,01 ± 0,44L e avaliador 3: 1,02 ± 0,45L vs1,03 ± 0,47L). Além disso, o coeficiente de correlação intraclasse entre as duas identificações foi alto para todos os avaliadores (ICC entre 0,97 e0,99). Esses resultados sugerem que a inspeção visual é um método válido, objetivo e reprodutivo para a estimativa do EPOC RÁPIDO.

The objective of this study was to analyze the validity, reproducibility and objectivity of the visual inspection method during the identification of the fast component of excess post-exercise oxygen consumption (EPOC FAST). Ten healthy physically active men (age = 23.0 + 4.0 years; height = 176.4 + 6.8 cm; body mass = 72.4 + 8.2 kg; VO2MAX = 3.0 + 0.5 L.min-1) performed a maximal incremental exercise and a constant workload test until exhaustion corresponding to 110 percent of maximal workload reached during the maximal incremental exercise. Oxygen consumption was measured breath-by-breath for 10 minutes during the passive recovery after the constant workload test. EPOC FAST was mathematically and visually determined by three evaluators. Double visual determination of EPOC FAST was carried out by each evaluator for reproducibility determination. There were no significant differences between EPOCFAST values obtained by mathematical (0.98 ± 0.45 L) or visual method (1.04 ± 0.45 L; 1.02 ± 0.45 L and 1.02 ± 0.45 L). None significant difference was found between the first and second visual assessment carried out by the evaluators (evaluator 1: 1.04 ± 0.45 L vs 1.04 ± 0.49 L; evaluator 2: 1.02 ± 0.45 L vs 1.01 ± 0.44 L and evaluator 3: 1.02 ± 0.45 L vs 1.03 ± 0.47 L). Finally, coefficient of intra-class correlation between determinations was high for all evaluators (ICC from 0.97 to 0.99). These results suggest that the visual method is valid, objective and reproducible for determination of the EPOC FAST.