AimProviding consistent levels of oxygen saturation (SpO2) for infants in neonatal intensive care units is not easy. This study explored how effectively the Auto-Mixer® algorithm automatically adjusted fraction of inspired oxygen (FiO2) levels to maintain SpO2 within an intended range in extremely low birth weight infants receiving supplemental oxygen without mechanical ventilation.MethodsTwenty extremely low birth weight infants were randomly assigned to the Auto-Mixer® group or the manual intervention group and studied for 12 h. The SpO2 target was 85–93%, and the outcomes were the percentage of time SpO2 was within target, SpO2 variability, SpO2 >95%, oxygen received and manual interventions.ResultsThe percentage of time within intended SpO2 was 58 ± 4% in the Auto-Mixer® group and 33.7 ± 4.7% in the manual group, SpO2 >95% was 26.5% vs 54.8%, average SpO2 and FiO2 were 89.8% vs 92.2% and 37% vs 44.1%, and manual interventions were 0 vs 80 (p < 0.05). Brief periods of SpO2 < 85% occurred more frequently in the Auto-Mixer® group.ConclusionThe Auto-Mixer® effectively increased the percentage of time that SpO2 was within the intended target range and decreased the time with high SpO2 in spontaneously breathing extremely low birth weight infants receiving supplemental oxygen.

In this paper, the AUTO-MIXER, a medical support equipment for the reduction of risks associated with the inadequate supply of oxygen, is presented. The equipment automatically regulates the Inspired Oxygen Fraction (FIO2 concentration), which is supplied to the patient according to user parameters, measures of oxygen saturation and patient's status. The AUTO-MIXER is based on a fuzzy control system, which was implemented in a microcontroller using a Look-Up Table. The operation of the device was validated using simulated data and actual patients. The results show that the AUTO-MIXER is an important tool for decreasing the incidence of pathologies related to unsuitable handling (excess or lack) of oxygen.Keywords: Blender, fuzzy logic, newborn, pulse oxymetry, oxygen saturation. RESUMENEn este trabajo se presenta un equipo de apoyo médico, para disminuir el riesgo por suministro inadecuado de oxígeno; denominado AUTO-MIXER. El equipo desarrollado regula de manera automática y precisa la Fracción Inspirada de Oxígeno (concentración-FiO2), que se le suministra al paciente de acuerdo a los parámetros programados por el usuario, las medidas de la saturación de oxígeno y el estado del paciente. El AUTO-MIXER está basado en un sistema de control difuso, el cual fue implementado en un micro controlador usando una Look-Up Table. Para validar el funcionamiento del dispositivo, se realizaron diferentes pruebas con datos simulados y con pacientes reales; los resultados muestran que el AUTO-MIXER se vislumbra como una importante herramienta para disminuir la incidencia de las patologías, asociadas al manejo inadecuado (exceso o falta) del oxígeno.Palabras clave: mezclador, lógica difusa, neonato, pulsoximetría, saturación de oxígeno.