Doppler transcraneal, BIS y entropía como medición indirecta del flujo cerebral durante la anestesia total intravenosa en pacientes pediátricos / Transcranial Doppler ultrasound, bispectral index, and electroencephalographic monitoring of entropy during pediatric total intravenous anesthesia

OBJETIVOS: El Doppler transcraneal (DTC) es una técnica de monitorización no invasiva de la velocidad del flujo sanguíneo cerebral en las principales arterias intracraneales, especialmente las arterias del polígono de Willis. Nuestro propósito es analizar mediante Eco-Doppler pulsado, si durante la anestesia en pediatría, las alteraciones del flujo sanguíneo cerebral (FSC), se corresponden con modificaciones en los valores medidos de índice biespectral (BIS) y entropía [Estado (ES) y Respuesta (ER)]. MATERIAL Y MÉTODOS: Estudio observacional prospectivo y ciego, en 36 pacientes de 5 a 11 años, con anestesia general total intravenosa, para cirugía general menor. Se realizó inducción con propofol y fentanilo. Para el mantenimiento se utilizó propofol y remifentanilo en perfusión continua y cisatracurio. Se monitorizó el patrón hemodinámico y respiratorio, gases administrados, temperatura, patrón de hipnosis (BIS y entropía - ES y ER-), y patrón de FSC estimado (sonografía Doppler pulsada) en la arteria cerebral media. Se realizó un suavizamiento estadístico para el bruto de datos. Se obtuvieron los parámetros de índice de resistencia, índice de pulsatilidad, velocidad media y flujo sanguíneo estimado. Se determinaron correlaciones para los valores de BIS, ES, ER, índice de pulsatilidad, índice de resistencia, velocidad media, flujo sanguíneo estimado, CO2 espirado y temperatura obtenidos. Se determinó la existencia de modelos de regresión. RESULTADOS: La inducción presentó un patrón de alta resistencia (velocidades medias bajas, índices de pulsatilidad elevados) hasta obtener el valor más bajo de BIS y entropía ES (31 y 29). Durante el mantenimiento se presentó un patrón de sonografía más enlentecido (normalización de índice de pulsatilidad, índice de resistencia y velocidad media), existiendo correlación estadística y concordancia entre las modificaciones de flujo y los valores absolutos de Entropía y BIS (–Pearson– r >= ± 0,91. Concordancia Doppler-BIS de 95,6%); coincidentes con valores de BIS y ES de 35-45; y en el despertar, las velocidades de flujo se acercaron a cifras basales cuando los valores de BIS y ES ascendieron (90-98). Se detectaron modificaciones puntuales del FSC estimado coincidentes con elevación o descenso casi concomitante de BIS (r > 0,95), que presentó un ligero retraso no superior al minuto, y que no fueron detectadas de igual modo por entropía. CONCLUSIONES: Proporcionamos los patrones sonográficos durante la anestesia para propofol. Los sistemas de monitorización de hipnosis podrían ser considerados como sistemas indirectos de medición de flujo cerebral (siendo BIS el de mayor sensibilidad). El DTC permitiría objetivar modificaciones de flujo durante la anestesia relacionados con la profundidad de la hipnosis(AU)

BACKGROUND AND OBJECTIVE: Transcranial Doppler ultrasound is a noninvasive technique for monitoring the velocity of blood flow in the main intracranial arteries, particularly those in the circle of Willis. Our aim was to assess whether changes in cerebral arterial blood flow in anesthetized pediatric patients detected by pulsed Doppler ultrasound correlate with changes in the bispectral (BIS) index and electroencephalographic state and response entropy (ES and ER, respectively). MATERIAL AND METHODS: Prospective, blinded observational study of 36 pediatric patients (age range, 5 to 11 years) under total intravenous anesthesia for minor surgical procedures. Propofol and fentanyl were used for induction; propofol and remifentanil in continuous perfusion and a single dose of cisatracurium were used for maintenance. In all patients we monitored hemodynamic and respiratory patterns, gases, temperature, and hypnosis (BIS, ES and ER) as well as cerebral blood flow estimated by pulsed Doppler ultrasound in the middle cerebral artery. Raw data were subjected to statistical smoothing. The resistance index, pulsatility index, mean velocity, and estimated baseline cerebral blood flow were calculated from the Doppler sonogram. We then studied the correlations between the Doppler-derived values and BIS, ES, ER, fraction of end-tidal carbon dioxide, and temperature. The variables were entered into logistic regression. RESULTS: The pattern at induction indicated high resistance (low mean velocities and high pulsatility indexes) until the lowest BIS and ES values of 31 and 29, respectively, were reached. During maintenance, the Doppler sonogram pattern was slower (normalization of the pulsatility index, the resistance index, and mean velocity). Changes in flow and absolute entropy and BIS values were statistically correlated (Pearson’s r values >= 0.91); there was 95.6% agreement between Doppler values and BIS and agreement between BIS and ES values of 35-45. On awakening, flow velocities approached baseline values when BIS and ES rose to between 90 and 98. The estimated cerebral blood flow underwent fluctuations coinciding with an approximately concomitant increase or decrease in BIS (r > 0.95); the response of BIS was slightly delayed by no more than a minute but there was no corresponding response of entropy measurements. CONCLUSIONS:We report Doppler ultrasound patterns during anesthesia with propofol. Systems for monitoring hypnosis could be considered indirect measurements of cerebral blood flow; BIS measurements are more sensitive to flow change. Transcranial Doppler ultrasound facilitates the observation of changes in blood flow that occur at different levels of hypnosis during anesthesia(AU)

[Transcranial Doppler ultrasound, bispectral index, and electroencephalographic monitoring of entropy during pediatric total intravenous anesthesia]. / Doppler transcraneal, BIS y entropía como medición indirecta del flujo cerebral durante la anestesia total intravenosa en pacientes pediátricos.

BACKGROUND AND OBJECTIVE: Transcranial Doppler ultrasound is a noninvasive technique for monitoring the velocity of blood flow in the main intracranial arteries, particularly those in the circle of Willis. Our aim was to assess whether changes in cerebral arterial blood flow in anesthetized pediatric patients detected by pulsed Doppler ultrasound correlate with changes in the bispectral (BIS) index and electroencephalographic state and response entropy (ES and ER, respectively). MATERIAL AND METHODS: Prospective, blinded observational study of 36 pediatric patients (age range, 5 to 11 years) under total intravenous anesthesia for minor surgical procedures. Propofol and fentanyl were used for induction; propofol and remifentanil in continuous perfusion and a single dose of cisatracurium were used for maintenance. In all patients we monitored hemodynamic and respiratory patterns, gases, temperature, and hypnosis (BIS, ES and ER) as well as cerebral blood flow estimated by pulsed Doppler ultrasound in the middle cerebral artery. Raw data were subjected to statistical smoothing. The resistance index, pulsatility index, mean velocity, and estimated baseline cerebral blood flow were calculated from the Doppler sonogram. We then studied the correlations between the Doppler-derived values and BIS, ES, ER, fraction of end-tidal carbon dioxide, and temperature. The variables were entered into logistic regression. RESULTS: The pattern at induction indicated high resistance (low mean velocities and high pulsatility indexes) until the lowest BIS and ES values of 31 and 29, respectively, were reached. During maintenance, the Doppler sonogram pattern was slower (normalization of the pulsatility index, the resistance index, and mean velocity). Changes in flow and absolute entropy and BIS values were statistically correlated (Pearson's r values > or = 0.91); there was 95.6% agreement between Doppler values and BIS and agreement between BIS and ES values of 35-45. On awakening, flow velocities approached baseline values when BIS and ES rose to between 90 and 98. The estimated cerebral blood flow underwent fluctuations coinciding with an approximately concomitant increase or decrease in BIS (r > 0.95); the response of BIS was slightly delayed by no more than a minute but there was no corresponding response of entropy measurements. CONCLUSIONS: We report Doppler ultrasound patterns during anesthesia with propofol. Systems for monitoring hypnosis could be considered indirect measurements of cerebral blood flow; BIS measurements are more sensitive to flow change. Transcranial Doppler ultrasound facilitates the observation of changes in blood flow that occur at different levels of hypnosis during anesthesia.