[COVID-19: Association of gasometric parameters at admission with in-hospital mortality]. / COVID-19: Parámetros gasométricos al ingreso y su asociación con mortalidad hospitalaria.

INTRODUCTION: At the beginning of the SARS-CoV-2 pandemic, acute respiratory failure has been the most important cause of hospitalization in patients with COVID-19, being more severe in patients with comorbidities and risk factors. In these scenarios hypoxemia has been associated with increased mortality. Our objective was to identify parameters obtained from arterial blood gases (ABG) associated with mortality in patients with COVID-19 at hospital admission. METHODS: GSA samples obtained by breathing room air (FiO2 21%) processed in the clinical laboratory were retrospectively studied in an ABL90 flex analyzer (Radiometer). RESULTS: Acute respiratory alkalosis was the predominant acid-base disturbance. Considering those patients with respiratory failure (paO2 < 60 mmHg), "silent" hypoxemia was observed in 11/176 (6%) of studied patients. In a multivariate analysis, three gasometric parameters at admission showed a positive association with hospital mortality: paO2 (p=0.053), paO2/pO2e index (which expresses the paO2 adjusted to the paO2 expected for age) (p=0.047) and fractional saturation of hemoglobin (OxiHb%) (p=0.028). DISCUSSION: GSA generate a key contribution in understanding the pathophysiology of the COVID-19 patient: in the initial evaluation, monitoring and prognosis of this disease.

Introducción: En los inicios de la pandemia por SARSCoV-2 la insuficiencia respiratoria aguda ha sido la causa más importante de hospitalización inmediata en los pacientes con COVID-19 que acudían a los servicios de urgencias, siendo mayor la gravedad en pacientes con comorbilidades y factores de riesgo preexistentes; en estos escenarios la hipoxemia ha sido asociada a mortalidad. Nuestro objetivo fue identificar parámetros obtenidos de los gases en sangre arterial (GSA) asociados a mortalidad en pacientes con COVID-19 al ingreso hospitalario. Métodos: Se estudiaron retrospectivamente muestras de GSA obtenidos respirando aire ambiente (FiO2 21%) procesadas en el laboratorio clínico en un analizador ABL90 flex (Radiometer). Resultados: La alcalosis respiratoria aguda fue el disturbio ácido base predominante. Considerando aquellos pacientes con insuficiencia respiratoria (paO2 < 60 mmHg) se observó hipoxemia "silenciosa" en 11/176 (6%) de los pacientes estudiados. En un análisis multivariado tres parámetros gasométricos al ingreso mostraron asociación positiva a mortalidad hospitalaria: paO2 (p = 0.053), índice paO2/pO2e (que expresa la paO2 ajustada a la paO2 esperada para la edad) (p = 0.047) y saturación fraccional de hemoglobina (OxiHb%) (p = 0.028). Discusión: Los GSA generan un aporte clave en la comprensión de la fisiopatología del paciente COVID-19; en la evaluación inicial, seguimiento y pronóstico de esta enfermedad.

COVID-19: parámetros gasométricos al ingreso y su asociación con mortalidad hospitalaria / COVID-19: Association of gasometric parameters at admission with in-hospital mortality

Resumen Introducción : En los inicios de la pandemia por SARS-CoV-2 la insuficiencia respiratoria aguda ha sido la causa más importante de hospitalización inmediata en los pacientes con COVID-19 que acudían a los servicios de urgencias, siendo mayor la gravedad en pacientes con comorbilidades y factores de riesgo preexistentes; en estos escenarios la hipoxemia ha sido asociada a mortalidad. Nuestro objetivo fue identificar parámetros obtenidos de los gases en sangre arterial (GSA) asocia dos a mortalidad en pacientes con COVID-19 al ingreso hospitalario. Métodos : Se estudiaron retrospectivamente muestras de GSA obtenidos respirando aire ambiente (FiO2 21%) procesadas en el laboratorio clínico en un analizador ABL90 flex (Radiometer). Resultados : La alcalosis respiratoria aguda fue el dis turbio ácido base predominante. Considerando aquellos pacientes con insuficiencia respiratoria (paO2 < 60 mmHg) se observó hipoxemia "silenciosa" en 11/176 (6%) de los pacientes estudiados. En un análisis multivariado tres parámetros gasométricos al ingreso mostraron asocia ción positiva a mortalidad hospitalaria: paO2 (p = 0.053), índice paO2/pO2e (que expresa la paO2 ajustada a la paO2 esperada para la edad) (p = 0.047) y saturación fraccional de hemoglobina (OxiHb%) (p = 0.028). Discusión : Los GSA generan un aporte clave en la comprensión de la fisiopatología del paciente COVID-19; en la evaluación inicial, seguimiento y pronóstico de esta enfermedad.

Abstract Introduction : At the beginning of the SARS-CoV-2 pandemic, acute respiratory failure has been the most important cause of hospitalization in patients with COVID-19, being more severe in patients with comorbidi ties and risk factors. In these scenarios hypoxemia has been associated with increased mortality. Our objective was to identify parameters obtained from arterial blood gases (ABG) associated with mortality in patients with COVID-19 at hospital admission. Methods : GSA samples obtained by breathing room air (FiO2 21%) processed in the clinical laboratory were retrospectively studied in an ABL90 flex analyzer (Radi ometer). Results : Acute respiratory alkalosis was the predomi nant acid-base disturbance. Considering those patients with respiratory failure (paO2 <60 mmHg), "silent" hypox emia was observed in 11/176 (6%) of studied patients. In a multivariate analysis, three gasometric parameters at admission showed a positive association with hos pital mortality: paO2 (p=0.053), paO2/pO2e index (which expresses the paO2 adjusted to the paO2 expected for age) (p=0.047) and fractional saturation of hemoglobin (OxiHb%) (p=0.028). Discussion : GSA generate a key contribution in un derstanding the pathophysiology of the COVID-19 pa tient: in the initial evaluation, monitoring and prognosis of this disease.

Acid-base patterns in acute severe asthma.

BACKGROUND AND OBJECTIVES: Acid-base status in acute severe asthma (ASA) remains undefined; some studies report complete absence of metabolic acidosis, whereas others describe it as present in one fourth of patients or more. Conclusion discrepancies would therefore appear to derive from differences in assessment methodology. Only a systematic approach centering on patient clinical findings can correctly establish true acid-base disorder prevalence levels. METHODS: This study examines acid-base patterns in ASA (314 patients), taking into account both natural history of disease and treatment, in patients free of other diseases altering acid-base status. Data were collected from patients admitted for ASA without prior history of chronic bronchitis, emphysema, kidney or liver disease, heart failure, uncontrolled diabetes mellitus or gastrointestinal illness. Informed consent was obtained for all patients, after study protocol approval by the Institutional Review Board. RESULTS: Arterial blood gases, plasma electrolytes, lactate levels, and FEV(1) were measured on arrival. Severe airway obstruction was found with FEV(1) values of 25.6 ± 10.0%, substantial hypoxemia (PaO(2) 66.1 ± 11.9 mmHg) and increased A-a O(2) gradient (39.3 ± 12.3 mmHg) breathing room air. While respiratory alkalosis occurred in patients with better preservation of FEV1, respiratory acidosis was observed with more severe airway obstruction, as was increased lactate in the majority of patients, independent of PaO(2) and PaCO(2) levels. CONCLUSIONS: Predominant acid-base patterns observed in ASA in this patient population included primary hypocapnia, or less frequently, primary hypercapnia. Lactic acidosis occurred in 11% of patients and presented consistently as a mixed acid-base disorder. These findings suggest lactic acidosis results from the combined effects of both ASA and medication-related sympathetic effects.