Valor pronóstico de los parámetros gasométricos del dióxido de carbono en pacientes con sepsis. Una revisión bibliográfica / Prognostic value of gasometric parameters of carbon dioxide in resuscitation of septic patients. A bibliography review

El metabolismo anaerobio es clave en la fisiopatología del shock séptico. Actualmente disponemos de la saturación venosa central y mixta, y del lactato para monitorizar estos pacientes. Hay trabajos que han demostrado que la normalización de parámetros hemodinámicos y de oxigenación no previene la progresión del daño orgánico o de mayor mortalidad. Recientemente se ha propuesto como marcador de hipoperfusión tisular la diferencia venoarterial de pCO2 (ΔpvaCO2), equivalente al gasto cardiaco; un gradiente elevado se ha relacionado con resultados adversos. Así mismo se ha propuesto la ratio ΔpvaCO2 entre diferencia de contenido arteriovenoso de oxígeno (ΔCavO2): ΔpvaCO2/ΔCavO2, también la ratio diferencia de contenido venoarterial de CO2 entre ΔCavO2: ΔCvaCO2/ΔCavO2, como marcadores de metabolismo anaerobio. Ambas ratios elevadas están relacionadas con mayores niveles de lactato y peor pronóstico. Por lo tanto, en pacientes con sepsis pudiera ser importante la combinación de objetivos de reanimación para mejorar los resultados (AU)

The anaerobic metabolism is the cornerstone in physiopathology of septic shock. Nowadays we have both the central or mixed venous oxigen saturation and lactate levels to monitoring the metabolism in septic patients. Some studies have shown that normalization of systemic hemodynamic and oxygen metabolism variables not prevent progression to multiorgan damage and death. Recently has been proposed the venous-to-arterial carbon dioxide difference (ΔpvaCO2) as an alternative marker of tissue hypoperfusion, like Cardiac Index. High ΔpvaCO2 predicts adverse outcomes. Also has been proposed both, the ratio between the ΔpvaCO2 and arterial-to-venous oxygen content difference (ΔCavO2): ΔpvaCO2/ΔCavO2; and, the ratio between venous-to-arterial carbon dioxide difference (ΔCvaCO2) and ΔCavO2: ΔCvaCO2/ΔCavO2, as markers of anaerobic metabolism. Both of high ratios are related to high levels of lactate and worse prognosis. Therefore in patients with sepsis the combination of markers of resuscitation could be important to improve the outcomes (AU)

Selection of sulfur oxidizing bacterium for sulfide removal in sulfate rich wastewater to enhance biogas production

Sulfur oxidizing bacteria (SOB) were isolated and tested in order to remove sulfide from high sulfate wastewater to reduce the amount of hydrogen sulfide (H2S) in the produced biogas. A promising SOB isolate, designated as isolate T307, was selected due to its best sulfide removal (86.7 percent) in the effluent of a sulfate reduction reactor (SRR) over a 24 hrs incubation. The bacterium was able to grow better as a mixotroph (yeast extract as a carbon source) than as a chemolithoautotroph. In addition, as a heterotroph, the bacterium grew well with yeast extract and peptone. Based on partial 16S rRNA gene sequence, the isolated T307 was an Alcaligenes sp. and was able to convert most of sulfide species (total sulfide: TS; dissolved sulfide: DS and H2S) into elemental sulfur or sulfate over a 20 hrs period of cultivation by controlling the speed of shaking. In a biogas reactor set, after pre-treating a sulfide medium with Alcaligenes sp. T307 there was a much higher specific yield of CH4 (238 ml CH4 g-1COD removed) and more biogas (154 ml L-1 d-1) was produced with the biogas containing more methane (48.1 percent CH4, 51.5 percent CO2 and 0.41 percent H2S) in comparison to a control with a specific yield of CH4, (72 ml CH4 g-1COD removed) 86 ml L-1 d-1 biogas produced with a composition of 35.5 percent CH4, 63.7 percent CO2 and 0.86 percent H2S.