Application of preoperative assessment of pain induced by venous cannulation in predicting postoperative pain in patients under laparoscopic nephrectomy: a prospective observational study.

BACKGROUND: Postoperative pain is the most prominent concern among surgical patients. It has previously been reported that venous cannulation-induced pain (VCP) can be used to predict postoperative pain after laparoscopic cholecystectomy within 90 mins in the recovery room. Its potential in predicting postoperative pain in patients with patient-controlled intravenous analgesia (PCIA) is worth establishing. The purpose of this prospective observational study was to investigate the application of VCP in predicting postoperative pain in patients with PCIA during the first 24 h after laparoscopic nephrectomy. METHODS: One hundred twenty patients scheduled for laparoscopic nephrectomy were included in this study. A superficial vein on the back of the hand was cannulated with a standard-size peripheral venous catheter (1.1 × 3.2 mm) by a nurse in the preoperative areas. Then the nurse recorded the VAS score associated with this procedure estimated by patients, and dichotomized the patients into low response group (VAS scores < 2.0) or high response group (VAS scores ≥2.0). After general anesthesia and surgery, all the patients received the patient-controlled intravenous analgesia (PCIA) with sufentanil. The VAS scores at rest and on coughing at 2 h, 4 h, 8 h, 12 h, 24 h, the effective number of presses and the number of needed rescue analgesia within 24 h after surgery were recorded. RESULTS: Peripheral venous cannulation-induced pain score was significantly correlated with postoperative pain intensity at rest (rs = 0.64) and during coughing (rs = 0.65), effective times of pressing (rs = 0.59), additional consumption of sufentanil (rs = 0.58). Patients with venous cannulation-induced pain intensity ≥2.0 VAS units reported higher levels of postoperative pain intensity at rest (P < 0.0005) and during coughing (P < 0.0005), needed more effective times of pressing (P < 0.0005) and additional consumption of sufentanil (P < 0.0005), and also needed more rescue analgesia (P = 0.01) during the first 24 h. The odds of risk for moderate or severe postoperative pain (OR 3.5, 95% CI 1.3-9.3) was significantly higher in patients with venous cannulation-induced pain intensity ≥2.0 VAS units compared to those <2.0 VAS units. CONCLUSIONS: Preoperative assessment of pain induced by venous cannulation can be used to predict postoperative pain intensity in patients with PCIA during the first 24 h after laparoscopic nephrectomy. TRIAL REGISTRATION: We registered this study in a Chinese Clinical Trial Registry (ChiCTR) center on July 6 2019 and received the registration number: ChiCTR1900024352.

Novel multimodal analgesia regimen improves post-TACE pain in patients with hepatocellular carcinoma.

BACKGROUD: Transarterial chemoembolization (TACE) is the primary palliative treatment for patients with unresectable hepatocellular carcinoma (HCC). However, it is often accompanied by postoperative pain which hinder patient recovery. This study was to examine whether preemptive parecoxib and sufentanil-based patient controlled analgesia (PCA) could improve the pain management in patients receiving TACE for inoperable HCC. METHODS: From June to December 2016, 84 HCC patients undergoing TACE procedure were enrolled. Because of the willingness of the individuals, it is difficult to randomize the patients to different groups. We matched the patients' age, gender and pain scores, and divided the patients into the multimodal group (n = 42) and control group (n = 42). Patients in the multimodal group received 40 mg of parecoxib, 30 min before TACE, followed by 48 h of sufentanil-based PCA. Patients in the control group received a routine analgesic regimen, i.e., 5 mg of dezocine during operation, and 100 mg of tramadol or equivalent intravenous opioid according to patient's complaints and pain intensity. Postoperative pain intensity, percentage of patients as per the pain category, adverse reaction, duration of hospital stay, cost-effectiveness, and patient's satisfaction were all taken into consideration when evaluated. RESULTS: Compared to the control group, the visual analogue scale scores for pain intensity was significantly lower at 2, 4, 6, and 12 h (all P < 0.05) in the multimodal group and a noticeably lower prevalence of post-operative nausea and vomiting in the multimodal group (31.0% vs. 59.5%). Patient's satisfaction in the multimodal group was also significantly higher than that in the control group (95.2% vs. 69.0%). No significant difference was observed in the duration of hospital stay between the two groups. CONCLUSION: Preemptive parecoxib and sufentanil-based multimodal analgesia regime is a safe, efficient and cost-effective regimen for postoperative pain control in HCC patients undergoing TACE.

[Assessment of efficacy of hypertonic saline - hydroxyethylstarch in haemorrhagic shock]. / Intérêt du mélange sérum salé hypertonique-hydroxyéthylamidon lors du choc hémorragique.

OBJECTIVE: Assessment of haemodynamic, respiratory and renal effects of hypertonic saline-hydroxyethyl starch (HyperHES) in critically ill-patients with hemorrhagic shock. PATIENTS AND METHODS: Seventeen mechanically ventilated patients with hemorragic shock benefiting from a cardiovascular monitoring by PiCCO device and requiring rapid volume loading. Two hundred and fifty milliliters of HyperHES were given over 5 minutes. The efficacy of volume loading was assessed by the measure of the systolic arterial pressure (SAP), cardiac index (CI), stroke volume variation (SVV) and the indexed systemic vascular resistance (iSVR). Studied parameters were assessed at baseline, 5, 30, 60 and 180 minutes after the end of HyperHES infusion. RESULTS: SAP (105 + or - 23 vs 77 + or - 10; p<0.001) and CI (4.8 + or - 1.1 vs 3.5 + or - 0.9; p<0.001) were significantly increased whereas iSVR (1175 + or - 310 vs 1501 + or - 337; p<0.01) and SVV (13 + or - 7 vs 20 + or - 5; p<0.01) were significantly decreased 5 minutes after the HyperHES infusion. Sodium (145 + or - 6 vs 136 + or - 5; p<0.001) and chloride (118 + or - 7 vs 107 + or - 6; p<0.001) were increased 5 minutes after the infusion. The PaO(2)/FiO(2) ratio as the extravascular lung water was not influenced by the infusion. The follow-up of renal parameters during the three first days (creatinemia, uremia and diuresis) did not revelead significant variations. CONCLUSION: In patients with hemorrhagic shock, the infusion of hypertonic saline (7.5%) hydroxyethyl starch association was followed by an increase in SAP, CI serum sodium and chloride concentrations. STUDY DESIGN: Prospective observational study.

Avaliação da Densidade dos anestésicos locais e da combinação com adjuvantes: estudo em laboratório / Assessment of the densities of local anesthetics and their combination with adjuvants: an experimental study / Evaluación de la densidad de los anestésicos locales y de la combinación con adyuvantes: estudio en laboratorio

JUSTIFICATIVA E OBJETIVOS: Uma das mais importantes propriedades físicas que afetam o nível da analgesia obtida após a injeção subaracnoidea de um anestésico local é sua densidade relativa à densidade do líquido cefalorraquidiano (LCR) a 37ºC. O objetivo deste trabalho foi determinar a densidade das soluções de anestésicos locais com e sem glicose e a combinação de anestésico local com adjuvantes a 20ºC, 25ºC e 37ºC em avaliação laboratorial. MÉTODO: A densidade (g.mL-1) foi medida como auxílio de um densímetro DMA 450, sensível a ± 0,00001 g.mL-1. A densidade e suas variações com a temperatura foram obtidas de todos os anestésicos locais e suas combinações com opioides a 20ºC, 25ºC e 37ºC. A solução é hiperbárica se sua densidade excede a 1,00099, a solução é hipobárica quando a densidade está abaixo de 1,00019 e é isobárica quando a densidade é maior que 1,00019 e menor que 1,00099. RESULTADOS: Ambos, anestésicos locais e adjuvantes, exibem diminuição da densidade quando se aumenta a temperatura. A 37ºC, todas as soluções que contêm glicose são hiperbáricas. Na ausência de glicose, todas as soluções são hipobáricas. A 37ºC, morfina, fentanil, sufentanil e clonidina são hipobáricas. CONCLUSÕES: A densidade dos anestésicos locais e adjuvantes diminui com o aumento da temperatura e aumenta com a adição de glicose. O conhecimento da baricidade, densidade relativa, ajuda na seleção do anestésico local mais adequado e dos adjuvantes para uso subaracnoideo.

BACKGROUND AND OBJECTIVES: The relative density of a local anesthetic in relation to that of the cerebrospinal fluid (CSF) at 37º C is one of the most important physical properties that affect the level of analgesia obtained after the subarachnoid administration of the drug. The objective of this study was to determine the density of local anesthetic solutions, with and without glucose, and the combination of the local anesthetic with adjuvants at 20º C, 25º C, and 37º C. METHODS: The density (g.mL-1) was determined by using a DMA 450 densimeter with a sensitivity of ± 0.00001 g.mL-1. The densities, and variations, according to the temperature were obtained for all local anesthetics and their combination with opioids at 20ºC, 25ºC, and 37ºC. The solution is hyperbaric if its density exceeds 1.00099, hypobaric when its density is lower than 1.00019, and isobaric when its density is greater than 1.00019 and lower than 1.00099. RESULTS: The densities of both local anesthetics and adjuvants decrease with the increase in temperature. At 37º C, all glucose-containing solutions are hyperbaric. In the absence of glucose, all solutions are hypobaric. At 37ºC, morphine, fentanyl, sufentanil, and clonidine are hypobaric. CONCLUSIONS: The densities of local anesthetics and adjuvants decrease with the increase in temperature and increase when glucose is added. The knowledge of the relative density helps select the most adequate local anesthetic to be administered in the subarachnoid space.

JUSTIFICATIVA Y OBJETIVOS: Una de las más importantes propiedades físicas que afectan el nivel de la analgesia obtenida después de la inyección subaracnoidea de un anestésico local, es su densidad relativa a la densidad del líquido cefalorraquídeo (LCR) a 37ºC. El objetivo de este trabajo fue determinar la densidad de las soluciones de anestésicos locales con y sin glucosa y la combinación de anestésico local con adyuvantes a 20ºC, 25ºC y 37ºC en evaluación laboratorial. MÉTODO: La densidad (g.mL-1) se midió con la ayuda de un densímetro DMA 450 sensible a ± 0.00001 g.mL-1. La densidad y sus variaciones con la temperatura se obtuvieron de todos los anestésicos locales y de sus combinaciones con opioides a 20ºC, 25ºC y 37ºC. La solución es hiperbárica si su densidad excede a 1.00099, la solución es hipobárica cuando la densidad está por debajo de 1,00019 y es isobárica cuando la densidad es mayor que 0,00019 y menor que 1,00099. RESULTADOS: Ambos anestésicos locales y los adyuvantes, arrojan una reducción de la densidad cuando se aumenta la temperatura. A 37ºC, todas las soluciones que contienen glucosa son hiperbáricas. Con la falta de glucosa, todas las soluciones son hipobáricas. A 37ºC, morfina, fentanil, sufentanil y clonidina son hipobáricas. CONCLUSIONES: La densidad de los anestésicos locales y adyuvantes se reduce con el aumento de la temperatura y aumenta con la adición de glucosa. El conocimiento de la baricidad, densidad relativa, ayuda a la selección del anestésico local más adecuado y de los adyuvantes para uso subaracnoideo.

Cost-effectiveness of analgesia after Caesarean section. A comparison of intrathecal morphine and epidural PCA.

BACKGROUND: Patient-controlled analgesia (PCA) techniques and intrathecal morphine are the most widely used treatments for post-Caesarean section pain. However these methods have not been compared with respect to analgesic quality and cost differences. METHODS: Fifty-three patients scheduled for elective or semi-urgent Caesarean section were randomized to receive for postoperative analgesia either epidural PCA with a mixture containing bupivacaine 0.06% and sufentanil 1 microg x ml(-1) or intrathecal morphine 0.15 mg together with the spinal anaesthetic and to be supplemented with paracetamol and tramadol. Analgesic efficacy, side-effects and costs were calculated during 48 h. RESULTS: VAS pain scores both at rest and during mobilization were lower in the PCA group, more particularly during the second postoperative day. Nausea and vomiting were more frequently registered in the morphine treated patients. PCA treated patients stayed longer in the recovery room but required fewer nurse interventions on the surgical ward. Manpower and drug costs were equal in both groups. The differences in total costs (Euro) amounted to euros 33 and were mainly caused by the more expensive equipment required for epidural PCA. Satisfaction and hospital discharge were similar for both treatments. CONCLUSIONS: It was concluded that epidural PCA induced better pain relief, caused less nausea/vomiting but was more expensive than intrathecal morphine.

Acute pain management: analysis, implications and consequences after prospective experience with 6349 surgical patients.

An acute pain service (APS) was set up to improve pain management after operation. We attempted to reduce the length of stay in the intensive care unit (ICU) of patients undergoing major surgery and to improve their homeostasis and rehabilitation using a multimodal approach (pain relief, stress reduction, early extubation). Patient-controlled epidural analgesia (PCEA) was a keystone of this approach. If PCEA was not applicable, patients received patient-controlled intravenous analgesia (PCIA) instead. Brachial plexus blockade (BPB) was used for surgery of the upper limbs. A computer based documentation system was used to help evaluate prospectively (a) the quality of analgesia, (b) adverse effects and risks of the special pain management techniques, and (c) cost-effectiveness. Patients receiving PCEA (n = 5.602) received a patient-titrated continuous infusion into the epidural space of either bupivacaine 0.175% or ropivacaine 0.2%, with 1 microg sufentanil mL(-1) added, followed by patient-controlled boluses of 2 mL (lockout time 20 min). For patients receiving PCIA (n = 634) an initial bolus of 7.5-15 mg piritramide was given, and the subsequent bolus was 2 mg (lockout time 10 min). A continuous infusion of bupivacaine 0.25% was administered to patients receiving BPB (n = 113). The dose was titrated to a dynamic visual analogue scale (VAS) scores < 40. The mean treatment periods were: BPB = 4.33 days, PCEA = 5.6 days, PCIA = 5.0 days. In the case of PCEA, the quality of pain relief, vigilance and satisfaction were superior compared with the PCIA method, which resulted in greater sedation and nausea. Although personal supervision was higher for the PCEA-treated patients, cost analysis revealed final savings of Euro 91,620 for the year 1998 obviating the need for an ICU stay totalling 433 days. Provided that PCEA is part of a fast-track protocol employing early tracheal extubation and optimal perioperative management, the associated initial higher costs will be recouped by the benefits to patients of better pain relief after surgery and fewer days subsequently spent in the ITU.

Pharmacokinetic model-driven infusion of sufentanil and midazolam during cardiac surgery: assessment of the prospective predictive accuracy and the quality of anesthesia.

OBJECTIVE: To evaluate the prospective predictive accuracy and the quality of anesthesia of pharmacokinetic model-driven infusion of sufentanil and midazolam designed to establish and maintain a plasma level of drug during cardiac surgery. DESIGN: Prospective analysis. SETTING: Operating room at a university hospital. PARTICIPANTS: Twenty adult patients younger than 75 years old scheduled for valvular or coronary artery bypass graft surgery. INTERVENTIONS: Patients were anesthetized using a variable predicted concentration of sufentanil (1 to 10 ng/mL) combined with a stable predicted concentration of midazolam (100 ng/mL). MEASUREMENTS AND MAIN RESULTS: For each patient, arterial samples were taken before (6 samples), during (2 samples), and after (2 samples) cardiopulmonary bypass (CPB). Plasma sufentanil and midazolam concentrations were measured by specific radioimmunoassay and high-performance liquid chromatography techniques. Predicted sufentanil and midazolam concentrations were derived using the data sets of Gepts et al and Maitre et al. The predictive performance, the percentage prediction error (PE), and the absolute percentage error were calculated for each sample. The bias, inaccuracy, and dispersion were assessed by determining the median of the individual medians of the prediction errors (MDPE), the median of the individual median of the absolute prediction errors (MDAPE), and the 10th and 90th percentiles of PE. For midazolam, the inaccuracy was low (MDAPE < 21%), but CPB was associated with a dilution of the measured concentration associated with a negative bias. For sufentanil, the inaccuracy was also low before CPB (MDAPE = 18%) but increased during and after CPB (MDAPE > 40%). During the whole procedure, the hemodynamic control necessitated only a few interventions. CONCLUSIONS: Pharmacokinetic model-driven infusion of sufentanil and midazolam using the pharmacokinetic sets of Gepts et al and Maitre et al is a safe and accurate anesthetic technique before CPB in adult patients undergoing cardiac surgery when high sufentanil (1 to 10 ng/mL) and low midazolam (100 ng/mL) predicted plasma concentrations are targeted.

Epidural bolus clonidine/morphine versus epidural patient-controlled bupivacaine/sufentanil: quality of postoperative analgesia and cost-identification analysis.

UNLABELLED: We compared the costs, quality of analgesia, and side effects of postoperative patient-controlled epidural analgesia (PCEA) with bupivacaine/sufentanil versus an epidural bolus (BOLUS) of clonidine/morphine in 68 patients with pancreatic surgery. Postoperative pain treatment was performed over 4 days: the PCEA pump was filled with bupivacaine 0.25% and sufentanil 2 micrograms/mL and set to 3-mL bolus and 10-min lockout time. BOLUS patients received injections of clonidine 150 micrograms plus morphine 2 mg on demand. Visual analog scale (VAS) score at rest and during coughing, heart rate (HR), systolic arterial pressure (SAP), incidence of postoperative nausea and vomiting, pruritus, duration of intestinal paralysis, hospital treatment, and costs for personnel and material were recorded. VAS scores during coughing (3 +/- 2.5 vs 5 +/- 3, P < 0.001) was higher, and HR (79 +/- 13 vs 89 +/- 15, P < 0.001), and SAP (110 +/- 18 vs 124 +/- 23, P < 0.001) were lower, in the BOLUS compared with the PCEA group. The incidence of hypotension (SAP < 80 mm Hg) was greater (6 vs 0, P < 0.001) in the BOLUS group. The incidence of all other side effects was comparable. The costs of personnel ($204 +/- $40 vs $166 +/- $38, P < 0.001) were higher in the BOLUS group, but the costs of material ($51 +/- $17 vs $87 +/- $18, P < 0.001) were higher in the PCEA group. Total costs ($62 +/- $9 vs $62 +/- $11 per day, P = 0.9) were comparable. We conclude that because of superior analgesia and reduced side effects at analogous costs, PCEA is preferable to the BOLUS technique for the treatment of postoperative pain. IMPLICATIONS: An epidural clonidine/morphine bolus technique resulted in inferior analgesia, more side effects, and comparable costs compared with a bupivacaine/sufentanil patient-controlled regimen in a randomized controlled trial after abdominal surgery.

[Effectiveness, side effects and costs of postoperative pain therapy: intravenous and epidural patient-controlled analgesia (PCA)]. / Wirksamkeit, Nebenwirkungen und Kosten postoperativer Schmerztherapie: Intravenöse und epidurale patientenkontrollierte Analgesie (PCA).

PURPOSE: Improvement of the quality of analgesia, reduction of side effects and costs by application of epidural (PCEA) in comparison to intravenous patient-controlled analgesia (PCA) in postoperative pain treatment. METHODS: 62 patients with upper abdominal surgery took part in this randomised prospective study which was approved by the local ethics committee. Epidural catheters were inserted at T 8/9 (group PCEA). General anaesthesia was performed with propofol, sufentanil 2 micrograms/kg, pancuronium, enflurane and O2:N2O = 1:2. Postoperative analgesia consisted of epidural bupivacaine 0.25% + sufentanil 2 micrograms/ml (BS). (bolus 0.05 ml/kg, lockout 10 min) in group PCEA, or of intravenous morphine (bolus 2 mg. lockout 10 min) in group PCA. The following parameters were recorded until the evening of postoperative day 4: pain intensity at rest (VASR, 1-10) and on coughing (VASH, 1-10), blood pressure, heart rate, blood gas analysis, ability to ambulate, pruritus, nausea/vomiting (PONV), patient satisfaction (0-4), time and expenses for postoperative pain treatment. RESULTS: Median VASR (1 vs 2) and VASH (3 vs 4.5) were lower, cough intensity (2 vs 1) and patient satisfaction score (4 vs 3) were higher in PCEA compared to PCA. Ability to ambulate, pruritus, PONV, haemodynamics, paO2 and paCO2 were comparable. Postoperative pain treatment with PCEA was more time-consuming (407 vs 299 min) and expensive (71 vs 40 S/day) than PCA. CONCLUSION: PCEA in comparison to PCA after major abdominal surgery provides superior analgesia with comparable side effects at approximately 80% higher costs.

La técnica anestésica en cirugía cardiovascular y el "fast-track" / The anesthetic technique for cardiovascular surgery and the \"fast-track\"

En la búsqueda de una técnica de anestesia para cirugía de revascularización apropiada para lograr extubación precoz, veloz recuperación de los pacientes y un alta rápida del hospital, disminuyendo de esta manera los costos ("fast track"), se ha diseñado una técnica barata, sencilla y que permite alcanzar esos objetivos. MATERIAL Y METODOS. Se seleccionaron 30 pacientes electivos divididos al azar en tres grupos iguales en los que se estudiaron las variables hemodinámicas de los efectos de la introducción en el circuito anestésico de uno de 3 agentes inhalatorios (halothano, enflurano e isoflurano) antes y después de circulación extracorpórea. Todos los pacientes tenían buena función ventricular, o ligeramente deteriorada (FEò0.4). Se premedicaron con lorazepam; la inducción se hizo con sulfentanilo (4 µg.kg1) y pancuronio (0.15 mg.kg.1); el mantenimiento se efectuó con los anestésicos inhalatorios y dosis repetidas de sufentanilo según necesidad. Se obtuvo excelente estabilidad hemodinámica. RESULTADOS. Ninguno de los inhalatorios fue más elegible que el otro. Antes de CEC los inhalatorios provocaron disminución de PA, IC, I/L, RVS y frec, probablemente por disminución del VO2. Después de CEC no impidieron la recuperación de los efectos de la misma, permitiendo que disminuyeran la frec y el IC, sin cambios en la PA y aumento de la RVS; el I/L se mantuvo bajo. Todos los pacientes se pudieron extubar dentro de las 4 a 6 horas de llegados a la Sala de Recuperación.

Postoperative pulmonary complications and morbidity after abdominal aneurysmectomy: a comparison of postoperative epidural versus parenteral opioid analgesia.

Patients undergoing aortic aneurysm repair have a high prevalence of coexisting cardiac and pulmonary disease, and the postoperative recovery is especially delayed by pulmonary complications. A review of all elective abdominal aneurysm repairs over a 29-month period was undertaken to evaluate the effectiveness of postoperative epidural analgesia in decreasing morbidity and mortality, and specifically pulmonary complications. Patients were placed into two groups; Group 1 (34 patients) used an epidural catheter for postoperative pain control, and Group II (31 patients) used standard parenteral opioid analgesia. The two groups were similar in preoperative combined factors including known risk factors for atherosclerotic cardiovascular disease, preexisting cardiac or pulmonary disease, and preexisting renal insufficiency. A statistically significant decrease (P = < 0.05) was found in both cardiac (P = 0.0002) and pulmonary (P = 0.019) complications in comparison, favoring Group I patients. A significant decrease was also seen in the time to liquid intake (P = 0.044), time out of bed to a chair (P = 0.002), length of stay in the Intensive Care Unit (P = 0.024), and overall hospital charges (P = 0.046) in favor of Group I patients. Although no significant difference (P = > 0.05) was seen in decreasing time to ambulation (P = 0.054), average time required on the ventilator (P = 0.053), or hospital days (P = 0.181), all of these did show a trend in favor of epidural catheter utilization. There were no complications or infections related to the use of the epidural catheter during this study period. In conclusion, the use of an epidural catheter for postoperative pain control has been shown to decrease time of intubation, time in the ICU, number of cardiac and pulmonary complications, which should lead to an overall decrease in hospital charges after elective repair of abdominal aortic aneurysms.

Comparison of fentanyl, sufentanil and alfentanil during awake craniotomy for epilepsy.

Neurolept anaesthesia is used during awake craniotomy for epilepsy surgery. This study compares analgesia, sedation and the side effects of the newer opioids sufentanil and alfentanil, with those of fentanyl in patients undergoing awake craniotomy. Thirty patients were randomized into three groups, each received droperidol, dimenhydrinate and the chosen opioid as a bolus followed by an infusion. The opioid doses used were fentanyl 0.75 microgram.kg-1 plus 0.01 microgram.kg-1 x min-1; sufentanil 0.075 microgram.kg-1 plus 0.0015 microgram.kg-1 x min-1, and alfentanil 7.5 micrograms.kg-1 plus 0.5 microgram.kg-1 x min-1. There were no differences in the requirements for droperidol, dimenhydrinate or in the incidence of complications among the three groups. The total doses of the opioids required were fentanyl 4.9 +/- 1.3 micrograms.kg-1, sufentanil 0.6 +/- 0.2 microgram.kg-1 and alfentanil 149 +/- 36 micrograms.kg-1. Two patients became uncooperative requiring general anesthesia. The conditions for surgery, electrocorticography and for stimulation testing were satisfactory in all other patients. We conclude that the newer opioids did not offer any benefit over fentanyl.