RESUMEN
BACKGROUND: We investigated the relationship between median nerve somatosensory evoked potentials (SSEPs) and the bispectral index (BIS) during alternating periods of consciousness and propofol-induced unconsciousness. METHODS: Loss of consciousness (LOC) was repetitively induced by bolus injections of propofol in 24 patients undergoing elective surgery in spinal anaesthesia. SSEP and the BIS were recorded during LOC and recovery of consciousness (ROC). The level of consciousness was clinically assessed by the observer's assessment of alertness/sedation scale. Propofol venous plasma concentrations were measured simultaneously. RESULTS: At LOC, all SSEPs latency components were prolonged (P<0.001), whereas amplitudes of the components > or = 45 ms were smaller (P=0.008) and the BIS values were lower (P<0.001). None of the EEG variables regained baseline levels during ROC. Regression analyses revealed that the SSEP components (five latencies and five amplitudes) explained 33% of the variance when predicting ROC; the BIS explained 12%. The combination of SSEP and BIS explained 37% of variance in this patient sample. Propofol venous plasma concentration was 1.2 (0.8) microg ml(-1) during LOC and 0.4 (0.5) microg ml(-1) during ROC. CONCLUSIONS: The present results indicate the usefulness of combining variables of the evoked and spontaneous EEG to measure different levels of consciousness, because the SSEP provide additional information beyond the BIS. Inter-individual variability of all the EEG variables limits their predictive potency of ROC after propofol infusion.
Asunto(s)
Anestésicos Intravenosos/farmacología , Estado de Conciencia/efectos de los fármacos , Potenciales Evocados Somatosensoriales/efectos de los fármacos , Monitoreo Intraoperatorio/métodos , Propofol/farmacología , Adulto , Anciano , Anestesia Raquidea , Anestésicos Intravenosos/sangre , Estado de Conciencia/fisiología , Electroencefalografía/efectos de los fármacos , Femenino , Humanos , Masculino , Nervio Mediano/fisiología , Persona de Mediana Edad , Propofol/sangre , Estudios Prospectivos , Tiempo de Reacción/efectos de los fármacos , Inconsciencia/fisiopatologíaRESUMEN
BACKGROUND: The Narcotrend is a computer-based EEG monitor designed to measure the depth of anaesthesia. The aim of the present study is to test the hypothesis that the intraoperative level of anaesthetic depth differs if decision-making is guided by Narcotrend monitoring or not. METHODS: Forty-eight patients undergoing elective surgery were randomized to receive a Narcotrend-controlled propofol/remifentanil anaesthetic regimen or standard clinical practice. In the EEG group, anaesthesia was adjusted to achieve a Narcotrend level of D2-E0, which is recommended for moderate to deep anaesthetic depth for surgery. EEG values were recorded continuously every 20 s in both groups. Depending on data distribution, group comparisons of the EEG parameters, propofol plasma concentration, and recovery characteristics were performed by analysis of variance for repeated measurements or non-parametric statistics. RESULTS: About 62 (sd 29)% of the Narcotrend values were within the target level in the EEG group during maintenance of anaesthesia; this was true for 64 (26)% of the data in the non-EEG group. The variance of the Narcotrend data was significantly lower in the EEG group compared with the non-EEG group [median: 0.4 (range: 3.5) vs 0.6 (2.5); P = 0.048]. There was no difference in propofol or remifentanil dosage, propofol plasma concentrations, and time for extubation. Ten minutes after extubation, visual analogue scores for nausea indicated a lower incidence in the Narcotrend group [7 (15) vs 24 (34); P = 0.005]. CONCLUSIONS: Guidance of anaesthesia with the Narcotrend-monitor leads to fewer deviations from a defined target than clinical assessment of anaesthetic depth only. This results in lower scores of nausea in the immediate period after anaesthesia.
Asunto(s)
Anestésicos Intravenosos/farmacología , Electroencefalografía/efectos de los fármacos , Monitoreo Intraoperatorio/métodos , Piperidinas/farmacología , Propofol/farmacología , Adulto , Analgésicos Opioides/farmacología , Periodo de Recuperación de la Anestesia , Anestésicos Combinados/farmacología , Anestésicos Intravenosos/sangre , Remoción de Dispositivos , Electroencefalografía/métodos , Femenino , Humanos , Intubación Intratraqueal , Masculino , Persona de Mediana Edad , Náusea y Vómito Posoperatorios/prevención & control , Propofol/sangre , Estudios Prospectivos , Remifentanilo , Procesamiento de Señales Asistido por Computador , Factores de TiempoRESUMEN
BACKGROUND AND OBJECTIVES: Early recovery after anaesthesia is gaining importance in fast track management. The aim of this study was to quantify psychomotor recovery within the first 24 h after propofol/remifentanil anaesthesia using the Short Performance Test (Syndrom Kurztest (SKT)), consisting of nine subtests. The hypothesis was that psychomotor performance remains reduced 24 h after anaesthesia. METHODS: Thirty-seven patients scheduled for elective surgery took part in the study. The SKT was performed on the day before general anaesthesia (T0), 10, 30, 90 min and 24 h after extubation (T1). Parallel versions were used to minimize learning effects. Anaesthesia was introduced and maintained with remifentanil/propofol as a target controlled infusion. Propofol plasma concentration was measured 10 and 90 min after extubation. Perioperative pain management included novaminsulfon and piritramide. RESULTS: Up till 90 min after surgery and anaesthesia, psychomotor performances were significantly reduced as the lower test results in all SKT subtests indicated (P < or = 0.007 vs. baseline T0). In the three memory subtests (ST 2, ST 8 and ST 9), psychomotor performance was still reduced on the first postoperative day (P < or = 0.005; T1 vs. T0). There was no correlation between propofol plasma concentration and the psychometric test results. CONCLUSIONS: Propofol/remifentanil-based target controlled general anaesthesia for surgery is associated with a reduced psychomotor function up to the first postoperative day. Further studies are needed to confirm the usefulness of the SKT in the perioperative period and to clarify which components in the perioperative period are responsible for a lower performance in the SKT.