Ventilación no invasiva con presión de soporte con volumen asegurado en un paciente con enfermedad pulmonar obstructiva crónica (EPOC) agudizada / No disponible

El paciente con EPOC exacerbado y encefalopatía hipercápnica puede plantear serios problemas al tratarle con ventilación mecánica no invasiva (VMNI). Aun no siendo una contraindicación para la VMNI, la falta de colaboración puede ser motivo de fracaso de la técnica. En la actualidad disponemos de modos ventilatorios limitados por presión que aseguran el volumen corriente aportado al paciente. El modo presión de soporte con volumen asegurado (AVAPS) nos ofrece esta opción. Existen pocas publicaciones sobre el uso de esta modalidad ventilatoria en la situación de fallo respiratorio agudo hipercápnico. Presentamos el caso de un paciente con EPOC exacerbado en situación de encefalopatía hipercápnica, tratado con éxito con este modo ventilatorio

The patient with exacerbated COPD and hypercapnic encephalopathy may pose serious problems regarding treatment with non-invasive mechanical ventilation (NIMV). Although no contraindication has been found for NIMV, lack of collaboration may be a reason for failure of the technique. We currently have ventilatory methods limited by the pressure that ensures the tidal volume provided to the patient. The average volume assured pressure support (AVAPS) offers us this option. There are few publications on the use of this ventilatory modality when there is acute hypercapnic respiratory failure. We present the case of a male patient with exacerbated COPD with hypercapnic encephalopathy who was successfully treated with this ventilatory mode

Molecular and Regulatory Properties of the Nitrate Reducing Systems of Rhodobacter

Phototrophic bacteria of the genus Rhodobacter possess several forms of nitrate reductase including assimilatory and dissimilatory enzymes. Assimilatory nitrate reductase from Rhodobacter capsulatus E1F1 is cytoplasmic, it uses NADH as the physiological electron donor and reduced viologens as artificial electron donors, and it is coupled to an ammonium-producing nitrite reductase. Nitrate reductase induction requires a high C/N balance and the presence of nitrate, nitrite, or nitroarenes. A periplasmic 47-kDa protein facilitates nitrate uptake, thus increasing nitrate reductase activity. Two types of dissimilatory nitrate reductases have been found in strains from Rhodobacter sphaeroides. One of them is coupled to a complete denitrifying pathway, and the other is a periplasmic protein whose physiological role seems to be the dissipation of excess reducing power, thus improving photoanaerobic growth. Periplasmic nitrate reductase does not use NADH as the physiological electron donor and is a 100-kDa heterodimeric hemoprotein that receives electrons through an electron transport chain spanning the plasma membrane. This nitrate reductase is regulated neither by the intracellular C/N balance nor by O2 pressure. The enzyme also exhibits chlorate reductase activity, and both reaction products, nitrite and chlorite, are released almost stoichiometrically into the medium; this accounts for the high resistance to chlorate or nitrite exhibited by this bacterium. Nitrate reductases from both strains seem to be coded by genes located on megaplasmids.