Intraoperative crystalloid utilization variability and association with postoperative outcomes: A post hoc analysis of two multicenter prospective cohort studies.

BACKGROUND: The optimal regimen for intravenous administration of intraoperative fluids remains unclear. Our goal was to analyze intraoperative crystalloid volume administration practices and their association with postoperative outcomes. METHODS: We extracted clinical data from two multicenter observational studies including adult patients undergoing colorectal surgery and total hip (THA) and knee arthroplasty (TKA). We analyzed the distribution of intraoperative fluid administration. Regression was performed using a general linear model to determine factors predictive of fluid administration. Patient outcomes and intraoperative crystalloid utilization were summarized for each surgical cohort. Regression models were developed to evaluate associations of high or low intraoperative crystalloid with the likelihood of increased postoperative complications, mainly acute kidney injury (AKI) and hospital length of stay (LOS). RESULTS: 7580 patients were included. The average adjusted intraoperative crystalloid infusion rate across all surgeries was to 7.9 (SD 4) mL/kg/h. The regression model strongly favored the type of surgery over other patient predictors. We found that high fluid volume was associated with 40% greater odds ratio (OR 1.40; 95% confidence interval 1.01-1.95, p = 0.044) of postoperative complications in patients undergoing THA, while we found no associations for the other types of surgeries, AKI and LOS CONCLUSIONS: A wide variability was observed in intraoperative crystalloid volume administration; however, this did not affect postoperative outcomes.

Clinical practice guide for the choice of perioperative volume-restoring fluid in adult patients undergoing non-cardiac surgery.

The present Clinical practice guide responds to the clinical questions about security in the choice of fluid (crystalloid, colloid or hydroxyethyl starch 130) in patients who require volume replacement during perioperative period of non-cardiac surgeries. From the evidence summary, recommendations were made following the GRADE methodology. In this population fluid therapy based on crystalloids is suggested (weak recommendation, low quality evidence). In the events where volume replacement is not reached with crystalloids, the use of synthetic colloids (hydroxyethyl starch 130 or modified fluid gelatin) is suggested instead of 5% albumin (weak recommendation, low quality evidence). The choice and dosage of the colloid should be based in the product characteristics, patient comorbidity and anesthesiologist's experience.

[Non-invasive mechanical ventilation in postoperative patients. A clinical review]. / Ventilación mecánica no invasiva en el postoperatorio. Revisión clínica.

Non-invasive ventilation (NIV) is a method of ventilatory support that is increasing in importance day by day in the management of postoperative respiratory failure. Its role in the prevention and treatment of atelectasis is particularly important in the in the period after thoracic and abdominal surgeries. Similarly, in the transplanted patient, NIV can shorten the time of invasive mechanical ventilation, reducing the risk of infectious complications in these high-risk patients. It has been performed A systematic review of the literature has been performed, including examining the technical, clinical experiences and recommendations concerning the application of NIV in the postoperative period.

[Non-invasive mechanical ventilation in the pre- and intraoperative period and difficult airway]. / Ventilación mecánica no invasiva en pre eintraoperatorio y vía aérea difícil.

Non-invasive mechanical ventilation is a method of ventilatory assistance aimed at increasing alveolar ventilation, thus achieving, in selected subjects, the avoidance of endotracheal intubation and invasive mechanical ventilation, with the consequent improvement in survival. There has been a systematic review and study of the technical, clinical experiences, and recommendations concerning the application of non-invasive mechanical ventilation in the pre- and intraoperative period. The use of prophylactic non-invasive mechanical ventilation before surgery that involves significant alterations in the ventilatory function may decrease the incidence of postoperative respiratory complications. Its intraoperative use will mainly depend on the type of surgery, type of anaesthetic technique, and the clinical status of the patient. Its use allows greater anaesthetic depth without deterioration of oxygenation and ventilation of patients.

[Clinical validation of minimally invasive evaluation of systolic function]. / Validación clínica de la valoración mínimamente invasiva de la función sistólica.

BACKGROUND AND OBJECTIVE: Pulse contour continuous cardiac output (PiCCO) monitoring by means of transpulmonary thermodilution provides 2 indices of systolic function: the cardiac function index and the global ejection fraction. Our aim was to compare these 2 PiCCO indices to the left-ventricular ejection fraction obtained by transthoracic echocardiography. MATERIAL AND METHODS: This was a prospective clinical study of 35 adult patients in the critical care unit of a university hospital. Each patient provided his or her own control data. Patients with marked changes in regional segment contractility or nonsinus rhythm were excluded. We collected patient variables, reason for admission to the critical care unit, the Acute Physiology and Chronic Health Evaluation II score, the reason for hemodynamic monitoring, and the infusion of vasoactive drugs at the time of the procedure. RESULTS: Statistically significant correlations were found between the left-ventricular ejection fraction and the global ejection fraction (r=0.79, P<.001) and the cardiac function index (r=0.66, P<.001). The mean (SD) difference between the left-ventricular ejection fraction and the global ejection fraction and the cardiac function index were 1.05% (10.2%) (range, 19.0% to 29.1%) and 0.001% (12.4%) (range, -24.3% to 24.3%), respectively. For predicting a left-ventricular ejection fraction of less than 40%, the area under the curve was 0.879 for the global ejection fraction and 0.805 for the cardiac function index of A global ejection fraction less than 13.5% and a cardiac function index less than 3.15 min(-1) predicted a left-ventricular ejection fraction less than 40% with sensitivities of 97% and 96% and specificities of 85% and 77%, respectively. CONCLUSIONS: In patients without marked changes in regional segment contractility, the global ejection fraction and the cardiac function index calculated by the PiCCO monitor offer a reliable and simple way to assess left-ventricular systolic function. Low values for these indicators suggest the need for echocardiographic assessment of left- and right-ventricular function.

Validación clínica de la valoración mínimamente invasiva de la función sistólica / Clinical validation of minimally invasive evaluation of systolic function

OBJETIVO: El monitor PiCCO®, mediante la técnica de termodilución transpulmonar (TDTP), ofrece dos índices de valoración de la función sistólica: el índice de función cardiaca (IFC) y la fracción de eyección global (FEG). En este estudio comparamos estos índices con la fracción de eyección del ventrículo izquierdo medida por ecocardiografía transtorácica. MATERIAL Y MÉTODO: Estudio clínico prospectivo de 35 pacientes adultos ingresados en una unidad de críticos de un hospital universitario. Cada paciente fue su propio control. Se excluyeron enfermos con alteraciones graves de la contractilidad segmentaria, así como los que tenían un ritmo cardiaco no sinusal. Se recogieron los datos demográficos, el motivo de ingreso en la unidad de cuidados críticos, el valor del APACHE II (Acute Physiology And Chronic Health Evaluation), el motivo de la monitorización hemodinámica y la infusión de fármacos vasoactivos en el momento de la exploración. Mediante el monitor PiCCO® se obtuvo el valor de la fracción de eyección global y el índice de función cardiaca. A su vez, se midió la fracción de eyección del ventrículo izquierdo mediante ecocardiografía transtorácica. RESULTADOS: Se encontraron correlaciones estadísticamente significativas de la fracción de eyección del ventrículo izquierdo con la FEG y el IFC (r=0,79; p<0,001 y r=0,66; p<0,001, respectivamente). La diferencia media entre los valores de la fracción de eyección del ventrículo izquierdo medidos y estimados por FEG e IFC fue de 1,05 ± 10,2% (rango -19,0 a 29,1) y 0,001 ± 12,4% (rango -24,3 a 24,3) respectivamente. El área bajo la curva para estimar una fracción de eyección del ventrículo izquierdo inferior a 40% fue 0,879 y 0,805 para la FEG e IFC respectivamente. La FEG inferior a 13,5% y el IFC inferior a 3,15 min-1 detectan una fracción de eyección del ventrículo izquierdo inferior a 40% con una sensibilidad del 97% y 96% y una especificidad del 85% y 77%, respectivamente. CONCLUSIONES: En pacientes sin alteraciones severas de la contractilidad segmentaria, los índices de contractilidad FEG e IFC obtenidos con el monitor PiCCO® constituyen una herramienta fiable y sencilla para la valoración de la función sistólica del ventrículo izquierdo. Valores bajos de estos índices nos deben incitar a realizar un estudio ecocardiográfico para valorar la función ventricular derecha e izquierda(AU)

BACKGROUND AND OBJECTIVE: Pulse contour continuous cardiac output (PiCCO) monitoring by means of transpulmonary thermodilution provides 2 indices of systolic function: the cardiac function index and the global ejection fraction. Our aim was to compare these 2 PiCCO indices to the left-ventricular ejection fraction obtained by transthoracic echocardiography. MATERIAL AND METHODS: This was a prospective clinical study of 35 adult patients in the critical care unit of a university hospital. Each patient provided his or her own control data. Patients with marked changes in regional segment contractility or nonsinus rhythm were excluded. We collected patient variables, reason for admission to the critical care unit, the Acute Physiology and Chronic Health Evaluation II score, the reason for hemodynamic monitoring, and the infusion of vasoactive drugs at the time of the procedure. RESULTS: Statistically significant correlations were found between the left-ventricular ejection fraction and the global ejection fraction (r=0.79, P<.001) and the cardiac function index (r=0.66, P<.001). The mean (SD) difference between the left-ventricular ejection fraction and the global ejection fraction and the cardiac function index were 1.05% (10.2%) (range, 19.0% to 29.1%) and 0.001% (12.4%) (range, –24.3% to 24.3%), respectively. For predicting a left-ventricular ejection fraction of less than 40%, the area under the curve was 0.879 for the global ejection fraction and 0.805 for the cardiac function index of A global ejection fraction less than 13.5% and a cardiac function index less than 3.15 min-1 predicted a left-ventricular ejection fraction less than 40% with sensitivities of 97% and 96% and specificities of 85% and 77%, respectively. CONCLUSIONS: In patients without marked changes in regional segment contractility, the global ejection fraction and the cardiac function index calculated by the PiCCO monitor offer a reliable and simple way to assess left-ventricular systolic function. Low values for these indicators suggest the need for echocardiographic assessment of left- and right-ventricular function(AU)

Validación clínica de la valoración mínimamente invasiva de la función sistólica / Clinical validation of minimally invasive evaluation of systolic function

OBJETIVO: El monitor PiCCO(R), mediante la técnica de termodilución transpulmonar (TDTP), ofrece dos índices de valoración de la función sistólica: el índice de función cardiaca (IFC) y la fracción de eyección global (FEG). En este estudio comparamos estos índices con la fracción de eyección del ventrículo izquierdo medida por ecocardiografía transtorácica. MATERIAL Y MÉTODO: Estudio clínico prospectivo de 35 pacientes adultos ingresados en una unidad de críticos de un hospital universitario. Cada paciente fue su propio control. Se excluyeron enfermos con alteraciones graves de la contractilidad segmentaria, así como los que tenían un ritmo cardiaco no sinusal. Se recogieron los datos demográficos, el motivo de ingreso en la unidad de cuidados críticos, el valor del APACHE II (Acute Physiology And Chronic Health Evaluation), el motivo de la monitorización hemodinámica y la infusión de fármacos vasoactivos en el momento de la exploración. Mediante el monitor PiCCO® se obtuvo el valor de la fracción de eyección global y el índice de función cardiaca. A su vez, se midió la fracción de eyección del ventrículo izquierdo mediante ecocardiografía transtorácica. RESULTADOS: Se encontraron correlaciones estadísticamente significativas de la fracción de eyección del ventrículo izquierdo con la FEG y el IFC (r=0,79; p<0,001 y r=0,66; p<0,001, respectivamente). La diferencia media entre los valores de la fracción de eyección del ventrículo izquierdo medidos y estimados por FEG e IFC fue de 1,05 ± 10,2% (rango -19,0 a 29,1) y 0,001 ± 12,4% (rango -24,3 a 24,3) respectivamente. El área bajo la curva para estimar una fracción de eyección del ventrículo izquierdo inferior a 40% fue 0,879 y 0,805 para la FEG e IFC respectivamente. La FEG inferior a 13,5% y el IFC inferior a 3,15 min-1 detectan una fracción de eyección del ventrículo izquierdo inferior a 40% con una sensibilidad del 97% y 96% y una especificidad del 85% y 77%, respectivamente. CONCLUSIONES: En pacientes sin alteraciones severas de la contractilidad segmentaria, los índices de contractilidad FEG e IFC obtenidos con el monitor PiCCO® constituyen una herramienta fiable y sencilla para la valoración de la función sistólica del ventrículo izquierdo. Valores bajos de estos índices nos deben incitar a realizar un estudio ecocardiográfico para valorar la función ventricular derecha e izquierda(AU)

BACKGROUND AND OBJECTIVE: Pulse contour continuous cardiac output (PiCCO) monitoring by means of transpulmonary thermodilution provides 2 indices of systolic function: the cardiac function index and the global ejection fraction. Our aim was to compare these 2 PiCCO indices to the left-ventricular ejection fraction obtained by transthoracic echocardiography. MATERIAL AND METHODS: This was a prospective clinical study of 35 adult patients in the critical care unit of a university hospital. Each patient provided his or her own control data. Patients with marked changes in regional segment contractility or nonsinus rhythm were excluded. We collected patient variables, reason for admission to the critical care unit, the Acute Physiology and Chronic Health Evaluation II score, the reason for hemodynamic monitoring, and the infusion of vasoactive drugs at the time of the procedure. RESULTS: Statistically significant correlations were found between the left-ventricular ejection fraction and the global ejection fraction (r=0.79, P<.001) and the cardiac function index (r=0.66, P<.001). The mean (SD) difference between the left-ventricular ejection fraction and the global ejection fraction and the cardiac function index were 1.05% (10.2%) (range, 19.0% to 29.1%) and 0.001% (12.4%) (range, –24.3% to 24.3%), respectively. For predicting a left-ventricular ejection fraction of less than 40%, the area under the curve was 0.879 for the global ejection fraction and 0.805 for the cardiac function index of A global ejection fraction less than 13.5% and a cardiac function index less than 3.15 min-1 predicted a left-ventricular ejection fraction less than 40% with sensitivities of 97% and 96% and specificities of 85% and 77%, respectively. CONCLUSIONS: In patients without marked changes in regional segment contractility, the global ejection fraction and the cardiac function index calculated by the PiCCO monitor offer a reliable and simple way to assess left-ventricular systolic function. Low values for these indicators suggest the need for echocardiographic assessment of left- and right-ventricular function(AU)

[Hydroxyethyl starch to protect renal function in laparoscopic surgery]. / Uso de hidroxietil almidón (Voluven) como protección de la función renal en cirugía laparoscópica.

OBJECTIVE: To evaluate the effect of prehydration with hydroxyethyl starch 130/0.4 (Voluven) compared to lactated Ringer solution in laparoscopic cholecystectomy. PATIENTS AND METHODS: We performed a randomized single-blind clinical trial on patients classified as ASA 1 and 2. The exclusion criteria were hypertension, kidney failure, treatment with diuretics or other antihypertensive drugs, diabetes, and use of nonsteroidal anti-inflammatory drugs. Balanced general anesthesia with remifentanil and sevoflurane was used. The total volume of administered fluids (including prehydration) was 2 mL x kg(-1) x h(-1) fasting plus 5 mL x kg(-1) x h(-1) during surgery. Group 1 was prehydrated 30 minutes before surgery with 500 mL of lactated Ringer solution in group 1; in group 2 the same quantity of Voluven was used. Ringer solution was used in both groups to provide additional fluids. Blood pressure was kept within 20% above or below baseline values. Standard anesthetic monitoring was performed. Intraoperative diuresis and creatinine clearance were recorded. The groups were compared using the t test; a P value of 05 or less was considered significant. RESULTS: Twenty-nine patients were enrolled in the study. Diuresis and creatinine clearance were significantly higher in the group that received prehydration with Voluven. The mean (SD) creatinine clearance rate was 176.44 (1433) mL x min(-1) in group 1 and 61.90 (6.6) mL x min(-1) in group 2 (P = .036). The mean volume of urine excreted was 1.71 (0.06) mL x kg(-1) x h(-1) in group 1 and 0.47 (0.02) mL x kg(-1) x h(-1) in group 2 (P = .017). CONCLUSION: Prehydration with Voluven can be an effective measure for protecting renal function against the adverse effects of pneumoperitoneum in laparoscopic surgery.

Uso de hidroxietil almidón (Voluven®) como protecciónde la función renal en cirugía laparoscópica / Hydroxyethyl starch to protect renal function in laparoscopic surgery

OBJETIVO: Valorar el efecto sobre la función renal dela prehidratación con hidroxietil almidón 130/0,4 (Voluven®) frente al Ringer Lactato en las colecistectomíaslaparoscópicas.PACIENTES Y MÉTODOS: Ensayo clínico aleatorizadosimple ciego en pacientes ASA I, II. Criterios de exclusión:hipertensión arterial, insuficiencia renal, tratamientocon diuréticos u otros antihipertensivos, diabéticos,uso de anti-inflamatorios no esteroideos. Anestesiageneral balanceada basada en remifentanilo-sevofluorano.Volumen total de fluidos administrados: (incluida laprehidratación): 2 mL Kg–1 h–1 ayuno + 5 mL Kg–1 h–1 deintervención. Prehidratación 30 minutos antes de laintervención con 500 mL de Ringer Lactado (RL) en elGrupo I y con la misma cantidad de Voluven® en el GrupoII. Resto de la fluidoterapia basada en Ringer Lactatoen ambos grupos. Mantenimiento de la presión arterialmedia ± 20% de los valores iniciales. Monitorizaciónanestésica habitual. Medida de diuresis intraoperatoriay aclaramiento de creatinina de diuresis intraoperatoria(ClCr). Comparación de grupos mediante t Student conun nivel de significación p ≤ 0,05.RESULTADOS: Se incluyeron 29 pacientes. Las diuresisy el aclaramiento de creatinina obtenidos fueron mayoresde forma estadísticamente significativa en el grupoen el que se realizó la prehidratación con Voluven®. ClCr(mL min–1) GRUPO I: 176,44 ± 14,33, GRUPO II:61,90 ± 6,6 (p = 0,036); Diuresis (mL Kg–1 h–1) GRUPO I:1,71 ± 0,06, GRUPO II 0,47 ± 0,02 (p = 0,017).CONCLUSIONES: La prehidratación con Voluven® puedeser una medida eficaz en la protección de la función renalfrente a los efectos adversos del neumoperitoneo en lacirugía laparoscópica (AU)

OBJETIVE: To evaluate the effect of prehydration withhydroxyethyl starch 130/0.4 (Voluven) compared tolactated Ringer solution in laparoscopic cholecystectomy.PATIENTS AND METHODS: We performed a randomizedsingle-blind clinical trial on patients classified as ASA 1and 2. The exclusion criteria were hypertension, kidneyfailure, treatment with diuretics or other antihypertensivedrugs, diabetes, and use of nonsteroidal anti-inflammatorydrugs. Balanced general anesthesia with remifentanil andsevoflurane was used. The total volume of administeredfluids (including prehydration) was 2 mL·kg-1·h-1 fastingplus 5 mL·kg-1·h-1 during surgery. Group 1 wasprehydrated 30 minutes before surgery with 500 mL oflactated Ringer solution in group 1; in group 2 the samequantity of Voluven was used. Ringer solution was used inboth groups to provide additional fluids. Blood pressurewas kept within 20% above or below baseline values.Standard anesthetic monitoring was performed.Intraoperative diuresis and creatinine clearance wererecorded. The groups were compared using the t test; a Pvalue of 05 or less was considered significant.RESULTS: Twenty-nine patients were enrolled in thestudy. Diuresis and creatinine clearance weresignificantly higher in the group that receivedprehydration with Voluven. The mean (SD) creatinineclearance rate was 176.44 (14.33) mL·min-1 in group 1and 61.90 (6.6) mL·min-1 in group 2 (P=.036). The meanvolume of urine excreted was 1.71 (0.06) mL·kg-1·h-1 ingroup 1 and 0.47 (0.02) mL·kg-1·h-1 in group 2 (P= .017).CONCLUSION: Prehydration with Voluven can be aneffective measure for protecting renal function againstthe adverse effects of pneumoperitoneum in laparoscopicsurgery (AU)

Intoxicación acuosa por uso de oxitocina / No disponible

No disponible

[Measurement of cardiac output after cardiac surgery: validation of a partial carbon dioxide rebreathing (NICO) system in comparison with continuous thermodilution with a pulmonary artery catheter]. / Medición del gasto cardíaco en el postoperatorio de cirugía cardiaca: validez de la reinhalación parcial de CO2 (NICO) frente a la termodilución continua mediante catéter de arteria pulmonar.

UNLABELLED: Cardiac output is usually monitored with a pulmonary artery catheter. However, because that method is not free of risk, devices have been designed in recent years to measure cardiac output in a way that is minimally invasive or fully noninvasive. Among such devices is the NICO monitor, which is based on a modified Fick equation (partial CO2 rebreathing). OBJECTIVE: To compare the accuracy of cardiac output measurements from the NICO monitor to measurements obtained by continuous thermodilution with a pulmonary artery catheter. MATERIAL AND METHODS: A nonprobabilistic, consecutive sample of 20 patients was enrolled in the early postoperative period after elective cardiac surgery (coronary or valve procedures) in the recovery ward. Seven measurements of cardiac output were taken simultaneously with each method in each patient. RESULTS AND CONCLUSIONS: Cardiac output estimated by the partial CO2 rebreathing method was lower than the measurement obtained by the pulmonary artery catheter. The percentage error between the 2 methods was 37%, indicating that the NICO monitor can not substitute for the traditional method. The better correlation found between normal-to-low cardiac output values and the absence of side effects of using the NICO method suggest that it might be indicated for detecting low cardiac output after cardiac surgery, especially when the risk-benefit ratio does not favor using a pulmonary artery catheter.

Medición del gasto cardíaco en el postoperatorio de cirugía cardíaca: Validez de la reinhalación parcial de CO2 (NICO(R)) frente a la termodilución continua mediante catéter de arteria pulmonar / Measurement of cardiac output after cardiac surgery: validation of a partial carbon dioxide rebreathing (NICO(R))system in comparison with continuous thermodilution with a pulmonary artery catheter

La monitorización del gasto cardíaco se ha realizado tradicionalmente a través del catéter de arteria pulmonar. Sin embargo, su uso no está exento de riesgos por lo que en los últimos años se han diseñado dispositivos con mínima o nula invasividad para el registro de este pará- metro, entre los que se encuentra el monitor NICO(R), basado en una modificación de la ecuación de Fick (reinhalación parcial de CO2 ). OBJETIVO: Comparar la precisión en la medida del gasto cardíaco del monitor NICO(R) frente a la termodilución continua por catéter de arteria pulmonar. MATERIAL Y MÉTODOS: Selección no probabilística y consecutiva a 20 pacientes en el postoperatorio inmediato de cirugía cardíaca electiva (coronaria o valvular) en la unidad de reanimación. En cada paciente se tomaron siete medidas simultáneas de gasto cardíaco por ambos métodos. RESULTADOS Y CONCLUSIONES: Se observa que la medición del gasto cardíaco por reinhalación parcial de CO2 infraestima a la obtenida por catéter de arteria pulmonar. El error porcentual encontrado entre ambos métodos de medida (37%)imposibilita que el monitor NICO(R) pueda sustituir al método tradicional. La mejor correlación encontrada para valores de gasto cardíaco norma- les-bajos junto a la ausencia de efectos adversos hace que este método pueda tener su indicación en la detección de estados de bajo gasto cardíaco en este tipo de pacientes, sobre todo cuando no hay relación beneficio- riesgo favorable para la utilización del catéter de la arteria pulmonar

Cardiac output is usually monitored with a pulmonary artery catheter. However, because that method is not free of risk, devices have been designed in recent years to measure cardiac output in a way that is minimally invasive or fully noninvasive. Among such devices is the NICO® monitor, which is based on a modified Fick equation (partial CO 2 rebreathing). OBJECTIVE: To compare the accuracy of cardiac output measurements from the NICO® monitor to measurements obtained by continuous thermo-dilution with a pulmonary artery catheter. MATERIAL AND METHODS :A non probabilistic, consecutive sample of 20 patients was enrolled in the early post- operative period after elective cardiac surgery (coronary or valve procedures)in the recovery ward. Seven measurements of cardiac output were taken simultaneously with each method in each patient. RESULTS AND CONCLUSIONS: Cardiac output estimated by the partial CO 2 rebreathing method was lower than the measurement obtained by the pulmonary artery catheter. The percentage error between the 2 methods was 37%, indicating that the NICO® monitor cannot substitute for the traditional method. The better correlation found be- tween normal-to-low cardiac output values and the absence of side effects of using the NICO® method suggest that it might be indicated for detecting low cardiac output after cardiac surgery, especially when the risk-benefit ratio does not favor using a pulmonary artery catheter

Comparison of the EEG-based SNAP index and the Bispectral (BIS) index during sevoflurane-nitrous oxide anaesthesia.

The BIS monitor (Aspect Medical Inc, Newton, USA) was the first electroencephalogram (EEG)-based monitor of the hypnotic effect reflected by a dimensionless figure ranging from 100 (awake state) to 0 (flat line EEG). Its widespread use makes it the most-studied and the best-known among same intended devices. Its algorithm processes low-frequency EEG oscillations in order to provide the Bispectral index. A BIS index ranging from 40 to 60 has been established as the proper for surgical performance. The BIS monitor permits a closer approach to the hypnotic component of anaesthesia beyond clinical signs and may reduce the probability of intraoperative awareness; therefore, it has become a recommended monitoring tool in routine practice. The SNAP monitor (Nicolet Biomedical, Madison WI, USA) is also intended for monitoring the hypnotic effect of anaesthetics, which is in turn displayed as an index ranging from 100 to 0, with 100 meaning a fully awake state and 0 meaning no brain activity. The algorithm of the SNAP monitor is featured by its additional processing of ultra-high EEG frequencies, which seem to be involved in the formation of consciousness. The use of these frequencies would theoretically improve responsiveness during increased brain activity. We studied its behaviour patterns and capability to monitor the hypnotic effect induced by sevoflurane-nitrous oxide by comparison with the BIS index. Seventy patients ASA I-III were induced with propofol, fentanyl and rocuronium, and maintained with sevoflurane-N(2)O. BIS and SNAP indices were simultaneously recorded before induction, after intubation, after incision, at the following 10, 30 and 50 minutes, awakening and extubation time points, together with heart rate and blood pressure. The Pearson correlation was R(2) = 0.68 (p < .05). The Bland and Altman test showed a bias of 14.3 for SNAP index values with respect to BIS index values. We concluded that the SNAP index correlates with variations in the hypnotic effect induced by sevoflurane-nitrous oxide anaesthesia when compared with the BIS index. In this context, a SNAP index ranging from 58 to 70 would be equivalent to the BIS index range 40 to 60 and, therefore, the accurate for surgical performance.