Comparison of Alfentanil and Fentanyl as Supplements to Induction of Anaesthesia with Thiopentone

In 120 premedicated patients undergoing general surgery, anaesthesia was induced with thiopentone 3 mg kg-1, preceded by alfentanil 4.5, 9.0 or 13.5 micrograms kg-1 or fentanyl 1.5 micrograms kg-1. The largest alfentanil dose attenuated the arterial blood pressure response to laryngoscopy and intubation better than the smaller doses of alfentanil. Changes in frontal muscle electromyogram or plasma cortisol and prolactin levels were not dependent on the adjuvant used. After thiopentone, 30, 7 and 17% of the patients given alfentanil 9.0 and 13.5 micrograms kg-1 and fentanyl 1.5 micrograms kg-1, respectively, reacted to pinching of the lower abdomen. Patients given alfentanil 4.5 micrograms kg-1 did not tolerate the endotracheal tube after recovery from suxamethonium block and their heart rate was increased 12 min after alfentanil administration. We conclude that the antinociceptive effect of alfentanil is distinctly shorter than that of fentanyl. The analgesic potency of alfentanil is between one sixth and one ninth of that of fentanyl.     

Alfentanil infusion for postoperative pain: a comparison of epidural and intravenous routes

The efficacy of intravenous (iv) and epidural infusions of alfentanil for postoperative pain relief was investigated in 24 patients (ASA physical status 1-2) who were scheduled for abdominal hysterectomy. The patients were allocated randomly to receive either epidural or iv alfentanil. In both groups, a loading dose of 15 micrograms.kg-1 was administered, followed by a constant rate infusion of 18 micrograms.kg-1.h-1 alfentanil for 20 h. Both routes provided similar degrees of analgesia; however, analgesia occurred earlier in the intravenously treated group (P less than 0.03). Mean plasma alfentanil concentrations (Cps) varied between 42 and 82 ng.ml-1 in the iv group and 23 and 68 ng.ml-1 in the epidural group, with higher concentrations in the iv group for the first 60 min only (P less than 0.01). Cps increased with infusion time, suggesting accumulation of alfentanil. After infusion ended, pain recurred at the same time in both groups, whereas the alfentanil Cps still were greater than 45 ng/ml. Postoperative epinephrine concentrations decreased after 60 min of infusion (P less than 0.02), whereas, after 6 h, cortisol levels decreased to preoperative values. Norepinephrine concentrations decreased only slightly. The only clinically meaningful effect on vital signs that occurred was an abrupt reduction of respiratory rate after the iv loading dose. PaCO2 increased to the same extent in both groups during the first 15 min only. The incidence of opioid-related side effects was similar in both groups. These results suggest that the iv and epidural routes were equally effective for providing postoperative pain control and controlling the postoperative response to surgical stress.     

Continuous opioid infusions for neurosurgical procedures: a double-blind comparison of alfentanil and fentanyl

The ability of continuous infusions of opioids to control hypertension at the end of neurosurgical procedures without compromising prompt emergence was studied in patients undergoing craniotomy for supratentorial tumours. Four infusion regimens were compared in a randomized double-blind fashion; three of alfentanil and one of fentanyl. Low-dose alfentanil was administered to nine patients (35.1 micrograms.kg-1 then a continuous infusion of 16.2 micrograms.kg-1.hr-1); mid-dose alfentanil to eight patients (70.2 micrograms.kg-1 then 32.4 micrograms.kg-1.hr-1); high-dose alfentanil to eight patients (105.3 micrograms.kg-1 then 48.6 micrograms.kg-1.hr-1). Eight additional patients were given fentanyl (8.3 micrograms.kg-1 then 1.6 micrograms.kg-1.hr-1). Using published values for the pharmacokinetic variables of alfentanil and fentanyl, modelling predicted stable concentrations of 60, 120, 180 ng.ml-1 for the alfentanil infusion regimens respectively and 2 ng.ml-1 with the fentanyl regimen. Maintenance anaesthesia comprised the opioid infusion, 50% N2O in O2 and isoflurane titrated to control mean arterial pressure (MAP) within 20% of ward MAP. Isoflurane was discontinued after closure of the dura. Nitrous oxide was discontinued at the same time as reversal of neuromuscular blockade. The opioid infusion was discontinued with closure of the galea. A greater time-averaged isoflurane concentration was required to control MAP within the prescribed limits in the low alfentanil group (ANOVA; P less than 0.05). The PaCO2 at two, five and 30 min after extubation were not different among groups. The times from discontinuing N2O to eye opening and tracheal extubation were not different. The time to follow commands was longer in the low alfentanil group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Metoclopramide does not decrease the incidence of nausea and vomiting after alfentanil for outpatient anaesthesia

Sixty patients were studied in a randomized, double-blind manner to determine whether metoclopramide added to droperidol decreased further the incidence of emetic symptoms (nausea, retching, vomiting) in outpatients receiving alfentanil anaesthesia for nasal surgery. Group 1 (n = 30) received metoclopramide 0.15 mg.kg-1 and Group 2 (n = 30) received placebo. In addition, both groups received droperidol 0.02 mg.kg-1 immediately before anaesthesia which was supplemented by alfentanil 20 micrograms.kg-1 at induction followed by an infusion of 0.25-1 micrograms.kg-1.min-1. Emetic symptoms were assessed 0-3 hr, 3-6 hr and 6-24 hr after surgery. Both groups received similar doses of alfentanil (mean +/- SD; Group 1 4641 +/- 1894 micrograms, Group 2 4714 +/- 1640 micrograms). The percentage of patients who had either nausea or vomiting at 0-3, 3-6 or 6-24 hr was 23%, 14% and 13% in Group 1; and 20%, 17% and 10% in Group 2. The overall incidence for each group was 8/30 (27%). There was no difference in the incidence of emetic symptoms between the groups at any time interval or throughout the study. Metoclopramide did not improve upon the antiemesis of droperidol during alfentanil anaesthesia for outpatient nasal surgery.     

A comparison of fentanyl and buprenorphine in total intravenous anesthesia using propofol during spinal surgery

A retrospective study was performed to compare the hemodynamic effect and postoperative pain relief of fentanyl (Group F, n = 11) and buprenorphine (Group B, n = 11) in total intravenous anesthesia (TIVA) using propofol during spinal surgery. All patients were premedicated with midazolam (3-5 mg) i.m. Anesthesia was maintained with propofol infusion, and increments of fentanyl or single dose of buprenorphine with 40% oxygen in air. Total doses of fentanyl and buprenorphine were 7.6 +/- 1.0 micrograms.kg-1 and 2.0 +/- 0.4 micrograms.kg-1, respectively. Maintenance doses of propofol (Group F: 5.5 +/- 0.8 mg.kg-1.h-1, Group B: 5.9 +/- 1.1 mg.kg-1.h-1) and vecuronium were not significantly different. Mean arterial pressures from 2 hours after incision to the end of surgery were elevated significantly in Group F than in Group B. Recovery time (Group F 12.5 +/- 6.1 min vs Group B 11.8 +/- 6.1 min) and extubation time (Group F 19.5 +/- 10.3 min vs Group B 15.0 +/- 7.0 min) were not different. At the end of anesthesia, seven patients in Group F and one patient in Group B (P < 0.01) complained of severe pain. All patients in Group F, and only two in Group B (P < 0.02) received analgesics within 20 hours. Neither nausea nor respiratory depression was found in both groups. This study suggests that buprenorphine would provide a more stable hemodynamic state and better postoperative pain relief than fentanyl in TIVA using propofol.     

A comparison of patient-controlled analgesia fentanyl and alfentanil for labour analgesia

PURPOSE: To determine the analgesic efficacy of equipotent doses of PCA (patient-controlled analgesia) fentanyl and PCA alfentanil for labour pain. METHODS: Twenty three, ASA I - II parturients between 32-42 wk gestational age in whom epidural analgesia was contraindicated were randomized to receive PCA fentanyl (Group F)or alfentanil (Group A). Plain numbered vials contained 21 ml fentanyl 50 microg x ml(-1) or alfentanil 500 microg x ml(-1). A one millilitre loading dose was administered. The PCA solution was prepared by diluting 10 ml study drug with 40 ml saline and the PCA pump was programmed to deliver a dose of 2 ml, delay of five minutes and a basal rate of 2 ml x hr(-1). Maternal measurements obtained were hourly drug dose, total dose, Visual Analog Pain Score (VAPS) q 30 min, sedation score q 1 hr and side effects. Neonates were assessed by 1,5, and 10-min Apgar scores, umbilical venous and arterial blood gases and neurobehavioural scores at four and 24 hr. RESULTS: Mean VAPS from 7 - 10 cm cervical dilatation were higher in Group A than in Group F (85.7+/-13.9 vs. 64.6+/-12.1; P<0.01) There were no inter-group differences in VAPS from 1-3 cm, or from 4-6 cm dilatation, in maternal sedation scores or side effects, or in neonatal outcomes. CONCLUSION: In the doses prescribed in this study, PCA fentanyl was found to provide more effective analgesia in late first stage labour than PCA alfentanil.     

Comparison of continuous epidural bupivacaine infusion plus either continuous epidural infusion or patient-controlled epidural injection of fentanyl for postoperative analgesia.

We compared the postoperative epidural analgesia provided by the continuous epidural infusion of bupivacaine supplemented with patient-controlled injection (PCA) of epidural fentanyl with that provided by a continuous infusion of bupivacaine supplemented with a continuous epidural infusion of fentanyl. Our patient population comprised 16 ASA physical status I or II patients undergoing laparotomy with a midline incision under general anesthesia combined with bupivacaine epidural analgesia. Post-operatively, a continuous epidural infusion of bupivacaine (0.1 mg.kg-1.h-1) was combined with epidural fentanyl given by either (a) PCA (15-micrograms bolus with a lockout interval of 12 min, n = 8) or (b) continuous infusion (1 microgram.kg-1.h-1, n = 8). In the case of inadequate pain relief in the latter group, the fentanyl infusion rate was increased by 10 micrograms/h. Analgesia evaluated by a visual analogue pain score and by a verbal pain score was similarly effective in both groups. The sedation score was also similar in both groups. The total dose of epidural fentanyl administered during the first 24 h was significantly lower in the PCA group than in the continuous infusion group (405 +/- 110 micrograms vs 1600 +/- 245 micrograms, P less than 0.001). The dose of fentanyl given during each 4-h interval ranged between 40 and 160 micrograms in the PCA group and 251 and 292 micrograms in the continuous infusion group. Clinically detectable respiratory depression was not observed in either group. In conclusion, epidural administration of 0.1 mg.kg-1.h-1 bupivacaine combined with fentanyl provides effective postoperative analgesia with a total dose of fentanyl required that is lower when fentanyl is administered by epidural PCA rather than by continuous epidural infusion.     

Total intravenous anaesthesia with propofol and alfentanil protects against postoperative nausea and vomiting

The incidence of postoperative nausea and vomiting and requirements for anti-emetic medication were assessed in 80 female patients undergoing day-case anaesthesia during assisted conception therapy. Anaesthesia was induced with alfentanil 50 micrograms.kg-1 and propofol 1 mg.kg-1; atracurium 0.5 mg.kg-1 was given to facilitate tracheal intubation. The patients were allocated to receive either total intravenous maintenance of anaesthesia with an infusion of propofol and increments of alfentanil (Group P) or inhalational maintenance of anaesthesia with nitrous oxide and enflurane (Group E). Postoperative nausea, retching, vomiting, requirements for anti-emetic therapy, and unplanned admission for overnight stay in hospital were recorded. Overall incidence of nausea was 64% in group E and 39% in Group P (P less than 0.05). Incidence of vomiting was 67% in Group E and 34% in Group P (P less than 0.05). Metoclopramide was requested by 62% of patients in Group E, and 32% of those in Group P (P less than 0.05); 21% of the patients in Group E were admitted to hospital overnight, while only 5% of the patients in Group P required unscheduled admission to hospital (P less than 0.05). We conclude that total intravenous anaesthesia with propofol and alfentanil is superior to inhalational maintenance with nitrous oxide and enflurane in that it is associated with less nausea and vomiting, less requirement for anti-emetic medication, and a lower probability of unplanned admission to hospital after day-care gynaecological surgery.     

Effect of peroperative analgesia on immediate postoperative oxygen consumption

Oxygen consumption in the immediate postoperative period was assessed in a series of twelve patients undergoing maxillofacial surgery, randomly assigned to two groups (n = 6 for each). The anaesthetic protocol was the same in all patients: premedication with flunitrazepam 30 micrograms.kg-1, induction with flunitrazepam 20 micrograms.kg-1, fentanyl 5 micrograms.kg-1, thiopentone 5 mg.kg-1, pancuronium bromide 80 micrograms.kg-1, and maintenance during the first three hours with flunitrazepam 10 micrograms.kg-1.h-1 and pancuronium 0.03 micrograms.kg-1.h-1. All the patients were given a continuous infusion of fentanyl during the whole length of the surgery: in Group I (GI), 3 micrograms.kg-1.h-1 and in Group II (GII), 1 microgram.kg-1.h-1. The patients in Group II were also given enflurane 1.2 +/- 0.3 vol %. During the immediate postoperative period, the parameters studied were measured by means of an Engstr?m Metabolism Calculator at the 15th, 30th, 45th, 60th, 120th and 240th minutes, and at the time of extubation. In GII, postoperative heart rate and lactic acid levels were higher than in GI (p less than 0.05). Both groups had oxygen consumption values greater than theoretical resting levels. However, postoperative oxygen consumption was greatly increased in GII with respect to GI during the first 4 hours (p less than 0.01). The respiratory quotient was greater in GI than in GII at the end of the study (p less than 0.05). These data indicate that the intraoperative analgesic technique influences postoperative oxygen consumption. A dose of fentanyl of 3 micrograms.kg-1.h-1 is more efficient than one of 1 microgram.kg-1.h-1 associated with enflurane.     

Post-anesthesia Recovery after Infusion of Propofol with Remifentanil or Alfentanil or Fentanyl in Morbidly Obese Patients

Background: The type of opioid used during general anesthesia in the morbidly obese influences recovery and the postoperative period. In a randomized clinical trial, the postoperative recovery profile and early period after general anesthesia with remifentanil, fentanyl and alfentanil were compared in morbidly obese patients. Material and Method: 60 morbidly obese patients with BMI >35 kg/m² (mean 43.31) undergoing open Roux-en-y gastric bypass were randomly divided into 3 groups: remifentanil (R), fentanyl (F), and alfentanil (A). Dosage of opioids was based on ideal body weight (IBW): fentanyl 5 mcg/kg for intubation followed by infusion of 0.025-0.05 mcg/kg/min; alfentanil 15 mcg/kg initially, then 1.0-1.5 mcg kg/min; and remifentanil 1 mcg/kg followed by infusion of 0.25-1.5 mcg/kg/min. Anesthesia was induced with infusion of propofol and oxygen with N₂O (1:1). After anesthesia, the duration to response to verbal command, spontaneous respiration, adequate respiration, and safe extubation were recorded.The incidence of postoperative nausea and vomiting were recorded. Using verbal scale for evaluation of postoperative pain, the early postoperative analgesia requirements were assessed. Results: Demographic profiles and duration of procedure did not differ between groups. A total dose of propofol was significantly lower in Group R compared with Groups A and F (P <0.05). Duration to spontaneous respiration, adequate respiration and safe extubation were significantly shorter in Group R compared with Group F (P <0.05). Shortly after anesthesia, significantly more patients in Group R required additional dose of analgesic than in Group F (P <0.05). Postoperative nausea and vomiting (PONV) occurred significantly more often in Group R compared with Group F (P <0.05). Recovery profile of Group A was more similar to Group R, and postoperative pain and PONV evaluation more similar to Group F. Conclusion: In morbidly obese individuals, alfentanil or fentanyl and remifentanil can be safely used, but there is a higher rate of PONV and postoperative pain in the remifentanil group.     

Alfentanil infusion for sedation in infants and small children during cardiac catheterization

We have analyzed several sedation techniques for paediatric cardiac catheterization which offer stable conditions for a few hours investigation, and maintain spontaneous breathing. In the present study, after premedication with oral flunitrazepam 0.1 mg.kg-1, 14 children aged 1-17 mo were sedated with an individually titrated alfentanil infusion. Every patient was sedated to a level which produced no reaction to pain or any discomfort. The induction dose and the maintenance requirement of alfentanil were 24 +/- 8 micrograms.kg-1 and 32 +/- 8 micrograms.kg-1.hr-1 (mean +/- SD), respectively. These doses were less in cyanotic than in acyanotic patients: 21 +/- 6 vs 28 +/- 8 micrograms.kg-1 and 29 +/- 10 vs 34 +/- 3 micrograms.kg-1.hr-1, respectively (P less than 0.05). The mean plasma concentration of alfentanil during maintenance of sedation was 79 +/- 23 ng.ml-1. Ventilation of two children was assisted for a short time after an incremental bolus of alfentanil. It is concluded that an alfentanil infusion technique with close monitoring of breathing is a practical sedation method for paediatric cardiac catheterization.     

Pharmacokinetics and pharmacodynamics of alfentanil infusions during general anesthesia

The pharmacokinetic and pharmacodynamic properties of alfentanil were studied in 64 surgical patients. Alfentanil was administered as a loading infusion (25-130 micrograms/kg) followed by a maintenance infusion (0.25-1.3 micrograms X kg-1 X min-1) as part of a nitrous oxide-narcotic-muscle relaxant technique. Although alfentanil doses of at least 50 micrograms/kg (in combination with thiopental, 2 mg/kg) were required to prevent hemodynamic changes during intubation, apnea or chest wall rigidity frequently occurred with alfentanil loading infusions exceeding 75 micrograms/kg. The alfentanil clearance rate was significantly lower in patients with liver dysfunction (2.3 +/- 1.3 vs 4.2 +/- 2.0 ml X kg-1 X min-1, mean +/- SD). In addition, the patients who required opioid antagonists to reverse postoperative respiratory depression had lower clearance rates (1.5 +/- 0.7 vs 4.1 +/- 1.9 ml X kg-1 X min-1) and longer elimination half-life values (406 +/- 304 vs 87 +/- 53 min). For maintenance of hemodynamic stability during superficial and intraabdominal operations, alfentanil serum concentration-response curves revealed ED95 values exceeding 300 ng/ml and 400 ng/ml, respectively. Our study also demonstrated a wide range of clinical responses to fixed doses of alfentanil. At equivalent doses, some patients required supplemental anesthetics, whereas others required an opioid antagonist. Careful titration of the alfentanil maintenance infusion is recommended to minimize the possibility of postoperative respiratory depression.     

Effect of naloxone infusion on analgesia and respiratory depression after epidural fentanyl

The efficacy of two dosage regimens of intravenous naloxone were compared to avoid nonrespiratory side effects and respiratory depression and yet to preserve analgesia (maximum tolerance to periostial pressure over the tibia) after administration of 200 micrograms epidural fentanyl. Three groups of eight patients were studied: group 1 patients received a loading dose of 0.4 mg IV naloxone followed by naloxone infusion at a rate of 10 micrograms.kg-1.hr-1. Group II patients received a loading dose of 0.2 micrograms naloxone followed by a naloxone infusion at a rate of 5 micrograms.kg-1.hr-1. Group III patients received a saline infusion at a rate of 20 ml/hr. Epidural fentanyl significantly increased tolerance to periostial pain in all three groups (respectively, +38 +/- 20%, +36 +/- 16%, and +35 +/- 14%) (mean +/- SD; P less than 0.05). The naloxone infusion significantly reduced this effect in groups I and II, respectively, -40 +/- 20% and -37 +/- 28% below prenaloxone levels) (P less than 0.05). Nonrespiratory side effects were also reversed in groups I and II. In group III, neither periostial analgesia nor nonrespiratory side effects were affected. The baseline slopes of VE/PETCO2 were 2.34 +/- 1.01, 2.14 +/- 0.66, and 2.68 +/- 1.14 L.min-1.mm Hg-1, respectively, in groups I, II, and III. Epidural fentanyl significantly decreased the slope below baseline levels in each group: -21 +/- 16%, -22 +/- 17%, and -19 +/- 32%, respectively, in groups I, II and III.(ABSTRACT TRUNCATED AT 250 WORDS)     

Epidural fentanyl plus bupivacaine 0.125 per cent for labour: analgesic effects

Ninety-five healthy nulliparous women, ASA physical status I-II with an uncomplicated pregnancy and single fetus in vertex position were given lumbar epidural analgesia. Patients in Group A (n = 35) received bupivacaine 0.125 per cent with epinephrine 1:800.000; Groups B (n = 30) and C (n = 30) received the same agents as Group A but with the addition to the initial dose of 50 or 100 micrograms of fentanyl respectively. All patients were evaluated for duration and quality of analgesia, duration of labour, method of delivery and total dose of bupivacaine used. The addition of either 50 or 100 micrograms of fentanyl resulted in longer duration of analgesia (93 +/- 9 min and 106 +/- 8 min respectively vs 55 +/- 7) and reduced bupivacaine total doses (64 +/- 0.03 and 55 +/- 1.5 respectively vs 109.5 +/- 1.3). Only the addition of 100 micrograms of fentanyl improved significantly the quality of analgesia (43.3 per cent of excellent scores vs 6.6 per cent in Group B and 5.7 per cent in Group A). Addition of fentanyl did not affect the duration of labour, the method of delivery and the neonatal neurobehaviour scores.     

Alfentanil inhibits muscle fasciculations caused by suxamethonium in children and in young adults

The effect of alfentanil on suxamethonium-induced muscle fasciculations was studied in a double-blind study in 34 children (mean age 6.8 years) and in 30 adults (mean age 20 years). After pretreatment with either alfentanil 50 micrograms kg-1 or saline, each patient was anaesthetized with a sleep dose of thiopental followed by suxamethonium 1.5 mg kg-1 for endotracheal intubation. Compared to the control groups, alfentanil significantly decreased the intensity of visible muscle fasciculations caused by suxamethonium. In children, the duration of muscle fasciculations was shorter in the alfentanil than in the control group. In adults, the intensity rather than the duration of fasciculations was attenuated by alfentanil. The inhibition of fasciculations caused by alfentanil was also demonstrated in children in the surface electromyogram recorded on the biceps. There was no circulatory response to endotracheal intubation in the groups pretreated with alfentanil.     

A randomized, double-blind comparison of lumbar epidural and intravenous fentanyl infusions for postthoracotomy pain relief. Analgesic, pharmacokinetic, and respiratory effects.

Although epidural opioids frequently are used to provide postoperative analgesia, several articles have suggested that the analgesia after epidural fentanyl is similar to that after an equal dose of fentanyl given intravenously. To address this issue further, 29 postthoracotomy patients were studied in a randomized, double-blinded trial comparing a lumbar epidural fentanyl infusion with an intravenous fentanyl infusion for analgesia, plasma fentanyl pharmacokinetics, and respiratory effects for 20 h postoperatively. In all patients in both groups, good analgesia was achieved (pain score less than 3, maximum 10) over a similar time course, although the patients receiving epidural infusion required a significantly larger fentanyl infusion dose than did the patients receiving intravenous infusion (group receiving epidural fentanyl infusion: 1.95 +/- 0.45 micrograms.kg-1.h-1; group receiving intravenous fentanyl infusion: 1.56 +/- 0.36 micrograms.kg-1.h-1; P = 0.0002). The time course for the plasma fentanyl concentrations was similar in the two groups, and plasma fentanyl concentrations were not significantly different at any sampling period (T7-T20; group receiving epidural fentanyl infusion: 1.8 +/- 0.5 ng/ml; group receiving intravenous fentanyl infusion: 1.6 +/- 0.6 ng/ml; P = 0.06). Similarly, calculated clearance values for the two groups were not significantly different (group receiving epidural fentanyl infusion: 0.95 +/- 0.26 l.kg-1.h-1; group receiving intravenous fentanyl infusion: 0.87 +/- 0.25 l.kg-1.h-1; P = 0.3). Both groups demonstrated a similar degree of mild to moderate respiratory depression postoperatively, which was assessed with continuous respiratory inductance plethysmography and sequential arterial blood gas analysis. Side effects (nausea, vomiting, pruritus) were mild and did not differ between groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of intravenous hypnotics on the actions of pipecuronium.

Seventy-five ASA Grades I-III patients (18-85 years, 45-90 kg) were randomized into five groups. All patients received N2O/O2 (2/1) and alfentanil: loading dose (LD) 0.015 mg kg-1 and maintenance dose (MD) 0.045 mg kg-1 h-1 (groups 1-4). Group 1 received propofol (LD 2 mg kg-1 and MD 6 mg kg-1 h-1); Group 2 etomidate (LD 0.3 mg kg-1 and MD 0.6 mg kg-1 h-1); Group 3 midazolam (LD 0.2 mg kg-1 and MD 0.120 mg kg-1 h-1); Group 4 methohexitone (LD 1.5 mg kg-1 and MD 4 mg kg-1 h-1); Group 5 dehydrobenzperidol 0.05-0.23 mg kg-1 and alfentanil (LD 0.100 mg kg-1 and MD 0.060 mg kg-1 h-1). The neuromuscular block induced by pipecuronium (50 micrograms kg-1) was evaluated. No statistically significant differences were found between the five groups as concerned degree of block (expressed as % twitch amplitude in response to the first of the TOF stimuli (Ta1) at intubation, T1 minimum and recovery to Ta1 = 20%, 25% and 75%. Slightly faster intubation was possible when midazolam was used in comparison with propofol, methohexitone or NLA and when etomidate was used in comparison with propofol. A wide range of individual values of maximal neuromuscular blocking activity was found.     

Low concentration/high volume is more effective than high concentration/low volume for postoperative continuous epidural analgesia with the combination of bupivacaine and fentanyl

In 40 females undergoing gynecologic laparotomy, lumbar epidural analgesia using a disposable infusion pump was continued for postoperative 48 hours. Then the analgesic effect of epidural bupivacaine (4.8 mg.kg-1) plus fentanyl (12 micrograms.kg-1) diluted with normal saline was prospectively compared between the two groups; high concentration/low volume group (HC/LV, 96 ml of total volume and 2 ml.h-1 of infusion rate, n = 20) versus low concentration/high volume group (LC/HV, 240 ml of total volume and 5 ml.h-1 of infusion rate, n = 20). On postoperative day 1, LC/HV group showed the significantly lower visual analog scale and verbal pain score at rest than HC/LV group (P < 0.05). No significant differences in the incidence of side effects were observed between the groups. These results suggest that when the equivalent dose is given, the volume rather than the concentration of the solution is important for postoperative continuous epidural analgesia with the combination of bupivacaine and fentanyl.     

Comparison of a combination of fentanyl and alfentanil with propofol in brief surgery

We studied 96 patients undergoing short gynecological procedures. Anaesthesia has been induced with fentanyl 1.5 micrograms/kg (45 patients) or alfentanil micrograms /kg (51 patients) and a hypnotic dose of propofol, and maintained with 70% N2O via facial mask. We observed a better and more rapid control of surgical analgesia with alfentanil, and an earlier recovery of postoperative psychophysical functions. Post-induction apnea has been more frequent and prolonged in the alfentanil group, but no difference in the time necessary to recover an adequate ventilation has been observed between the two groups. Alfentanil anaesthesia determined a more marked intraoperative bradycardia. By virtue of the speed of onset and the short duration of action, alfentanil is a suitable anaesthetic agent for short surgical procedures, particularly in day-stay patients.     

Anesthesia for craniotomy: a double-blind comparison of alfentanil, fentanyl, and sufentanil

Using a prospective, randomized, and double-blind study design, alfentanil (n = 15), fentanyl (n = 14), or sufentanil (n = 16), in combination with N2O, were administered to patients undergoing craniotomy for supratentorial tumor resection. Physicians were given two syringes, one of which was labeled as "load" for the initial loading dose and the other as "maintenance" for continuous infusion. The concentration of drug in each syringe was adjusted to permit administration on a milliliter per kilogram basis. The target loading doses for alfentanil, fentanyl, and sufentanil were 75, 10, and 1 microgram/kg, respectively, and initial infusion rates were 33.5, 2.0, and 0.3 microgram.kg-1.h-1, respectively. Additional supplementary boluses and changes in maintenance infusion rate were made according to predetermined guidelines. Isoflurane, in increasing 0.2% inspired increments, was used only when the maximum allowed opioid dose had been given (i.e., supplementary bolus doses equal to 75% of the calculated loading dose or supplementary bolus doses equal to 50% of the calculated loading dose combined with a 50% increase in the maintenance infusion rate). Opioid infusions were stopped at the time of bone flap replacement. Antihypertensive medications and naloxone were subsequently given at the discretion of the anesthesiologist. Group demographics were not different. Total volumes of drug were similar among groups indicating equipotent preparations. Administration of isoflurane, antihypertensive medications, and naloxone were not different among groups. Although decreases in blood pressure seen with induction were similar among groups, alfentanil-treated patients received ephedrine more frequently before intubation. Thirty minutes after entry into the postanesthesia recovery area, respiratory rate and pH were lowest in sufentanil-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)