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.     

Alfentanil sedation for cardiac catheterization of children with Fontan shunts

After Fontan operation, prolonged invasive cardiac assessment is often needed. This study is a clinical evaluation of the effectiveness of flunitrazepam premedication, EMLA cream, and alfentanil continuous infusion for management of children undergoing such catheterization. Fourteen consecutive subjects aged 5-20 yr with Fontan shunts (right atrium to pulmonary artery) undergoing elective haemodynamic and electrophysiological catheterization were sedated with an individually titrated alfentanil infusion. After oral premedication with flunitrazepam 2 mg, the mean induction dose and mean maintenance requirement of alfentanil were 4.4 +/- 2.7 micrograms.kg-1 and 10.3 +/- 8.6 micrograms.kg-1 x hr-1, respectively. Mean oxygen consumption during haemodynamic catheterization was 4.1 +/- 0.4 ml.kg-1 x min-1 with an average individual variation of 10%. For every patient, tranquil and stable conditions during catheterization could be produced. It is concluded that alfentanil infusion is a method of sedation of children and adolescents with Fontan shunts during haemodynamic and electrophysiologic catheterization. However, continuous monitoring of ventilation and an understanding of the slow circulation time after Fontan operation are essential with such sedation in these patients.     

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.     

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.     

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)     

Alfentanil pharmacokinetics in patients undergoing abdominal aortic surgery

The pharmacokinetics of alfentanil, 300 micrograms.kg-1 IV, were determined in patients undergoing elective abdominal aortic reconstruction. The mean age (+/- SD) of the patients was 64.3 +/- 7.4 yr; their mean weight was 74.7 +/- 13.8 kg. Five patients underwent aneurysm repair and six had aortobifemoral grafting. Serum alfentanil concentrations were measured by gas-liquid chromatography in samples drawn at increasing intervals over a 24-hr period. A three-compartment model was fitted to the concentration versus time data. The volume of the central compartment and the volume of distribution at steady state (Vdss) were 0.44 +/- 0.022 and 0.63 +/- 0.32 L.kg-1, respectively. Total drug clearance was 6.4 = 1.9 ml.min-1.kg-1. The elimination half-time was 3.7 +/- 2.6 hr. Patient age was positively correlated with both Vdss and elimination half-time. There were no significant correlations between the pharmacokinetic variables and the duration of aortic cross-clamping, the duration of surgery, or the rate or total volume of IV fluids infused intraoperatively. In general surgical patients, the elimination half-time of alfentanil has been reported to be 1.2-2.0 hr. Although the elimination half-time of alfentanil was longer in patients undergoing abdominal aortic surgery, alfentanil was eliminated much faster than either fentanyl or sufentanil in this patient population.     

Cerebrospinal fluid pressure in patients with brain tumors: impact of fentanyl versus alfentanil during nitrous oxide-oxygen anesthesia

The effects on the cerebrospinal fluid pressure (CSFP) of alfentanil and fentanyl were compared during nitrous oxide-oxygen (N2O-O2) anesthesia in 24 patients who had brain tumors. Monitored variables included CSFP (lumbar subarachnoid catheter), heart rate from electrocardiographic lead II, mean radial arterial blood pressure, and arterial blood gas tensions. General anesthesia was induced with thiopental, 5 mg/kg IV in divided doses, and maintained with 70% N2O in O2; ventilation was held constant (PaCO2 = 37.4 +/- 1.6 mm Hg [mean +/- SEM]). After baseline data were recorded, 16 subjects were randomly assigned to receive either 5 micrograms/kg fentanyl as an intravenous bolus or 50 micrograms/kg alfentanil as an intravenous bolus, followed by an infusion of alfentanil at 1 micrograms.kg-1.min-1. Monitored variables were continuously recorded for 15 min after opioid injection. A third group of 8 patients was studied subsequently; they received only N2O-O2 during a 15-min observation period and served as controls. Blood pressure was held constant with an intravenous infusion of 0.1% phenylephrine, as needed; noxious stimulation was carefully avoided. Cerebrospinal fluid pressure remained unchanged both in patients who received N2O-O2 alone and in those who received fentanyl-N2O-O2. By contrast, those who received alfentanil-N2O-O2 had a gradual increase in CSFP, reaching 30% above baseline values after 10 min and stabilizing thereafter. Although the absolute increase in CSFP during normocarbic alfentanil-N2O anesthesia was relatively small (9.5 +/- 1.3 mm Hg to 13.0 +/- 1.3 mm Hg [mean +/- SE], P less than 0.05), the absence of a similar effect after fentanyl administration suggests that precautionary measures such as hyperventilation are advisable if alfentanil is used for potentiating normocarbic N2O-O2 anesthesia in neurosurgical patients with intracranial mass lesions.     

The pharmacokinetics of alfentanil (R39209): a new opioid analgesic

The pharmacokinetics of alfentanil (R39209), a new short-acting opioid analgesic, have been studied in eleven patients. Six patients were given 50 micrograms/kg alfentanil and five patients 125 micrograms/kg as an intravenous bolus injection. Plasma concentrations were measured at intervals up to 6 h (50 micrograms/kg) or 8-10 h (125 micrograms/kg), using a specific radioimmunoassay technique. Plasma concentrations declined triexponentially in both groups. The initial elimination of alfentanil from the plasma was very rapid with 90% of the administered dose leaving the plasma within 30 min. The average half-lives for the three phases were similar for both groups. The combined mean (+/- SEM) half-lives for the 11 patients for the rapid and slow distribution phases were short (t 1/2 pi = 1.2 +/- 0.26 min, t 1/2 alpha = 11.6 +/- 1.63 min). The elimination half-life, t 1/2 beta was 94 +/- 5.87 min which is considerably shorter than that of other opioids. The mean (+/- SEM) total body clearance was 6.4 +/- 1.39 ml . kg-1 . min-1 and the volume of distribution (Vd) was 0.86 +/- 0.194 l/kg. The latter is considerably less than reported values for the chemically related drug, fentanyl, and suggests that alfentanil may have a lower tissue binding affinity than fentanyl. The rapid elimination and short duration of clinical action suggests the feasibility of repeated administration of alfentanil and its use by continuous intravenous infusion.     

Pharmacokinetics of alfentanil and clinical responses during cardiac surgery

This study assessed the pharmacokinetic and pharmacodynamic behaviour of alfentanil during and after coronary artery bypass grafting (CABG). Twenty-eight patients with good ventricular function having CABG were divided into three groups and premedicated with morphine 0.1 mg.kg-1 IM, scopolamine 0.005 mg.kg-1 IM and diazepam 0.1 mg.kg-1 PO. Group I patients received an infusion of 250 micrograms.kg-1 of alfentanil over one hour coincidental with a second infusion at 2.5 micrograms.kg-1.min-1 which was continued to the end of surgery. Patients in group II received 300 micrograms.kg-1 and 3.0 micrograms.kg-1.min-1 and patients in group III 350 micrograms.kg-1 and 3.5 micrograms.kg-1.min-1. The tracheas of all patients were intubated after receiving alfentanil 96 micrograms.kg-1 and pancuronium 0.15 micrograms.kg-1. Haemodynamic responses to intubation and surgical stimuli (greater than or equal to 20 per cent increase in heart rate and/or systolic blood pressure from control) were treated with isoflurane, one to two per cent inspired, until abolished. Blood samples were taken during and after surgery for plasma alfentanil concentrations which were determined by radioimmunoassay. After surgery the times to awakening and extubation, and alfentanil elimination half-life (t1/2B = 0.693/-k) were determined for each patient. Haemodynamic responses occurred in 20 patients. There were no significant differences in any variable among the groups. The times to awakening and extubation for all patients were 3.2 +/- 0.6 and 8.8 +/- 1.2 hr (mean +/- SEM) respectively. The elimination half-life for all patients was 5.1 +/- 1.0 hr (mean +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics and placental transfer of intravenous and epidural alfentanil in parturient women

Alfentanil was administered as a 30 micrograms/kg single intravenous injection to five healthy women scheduled for elective cesarean section (group A). In five pregnant women normal vaginal delivery was supported by epidural analgesia with a 30 micrograms/kg loading dose followed by a 30 micrograms/kg-1/hr-1 infusion of alfentanil (group B). Five healthy nonpregnant women scheduled for minor general surgery received 120 micrograms/kg alfentanil intravenously as a bolus before surgical incision (group C). In groups A and B plasma alfentanil concentrations, alfentanil plasma protein binding, and alpha 1-acid glycoprotein (alpha 1-AGP) concentrations were measured in maternal and umbilical arterial or venous blood samples at delivery. Multiple arterial sampling in groups A and C for measurement of alfentanil plasma concentration decay analysis indicated three-compartmental characteristics in most patients. In the pregnant population terminal half-life (t1/2 beta), volume of distribution at steady state (Vdss), and total plasma clearance (Clp) amounted to 103 +/- 67 min, 541 +/- 155 ml/kg and 6.48 +/- 0.85 ml/kg-1/min-1, respectively (mean +/- SD), and did not differ significantly in nonpregnant patients. In groups A and B the fetal-maternal ratios indicated a concentration gradient for the total plasma alfentanil content (ratio of total alfentanil concentrations in umbilical venous and maternal blood (Uv/M), 0.31 +/- 0.08 and 0.28 +/- 0.06 (mean +/- SD) in groups A and B respectively) with a larger protein binding capacity in maternal plasma (group A, 85 +/- 3%; group B, 90 +/- 1%) (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sedation for bronchofiberoscopy: comparison between propofol infusion and intravenous boluses of fentanyl and diazepam

Two methods of sedation were evaluated in unpremedicated patients undergoing elective bronchofiberoscopy. The patients were randomly allocated to receive either propofol infusion 1 mg kg-1 h-1 preceded by a 1 mg kg-1 bolus (15 patients) (the propofol group) or intravenous fentanyl 1 micrograms kg-1 and diazepam 0.05 mg kg-1 (15 patients) (the fentanyl+diazepam group). Thirteen patients were treated twice during the study period and sedated with both methods (the first treatment according to random order and the second with the method not used on the first occasion). A topical anaesthetic was applied to the selected nostril with two cotton swabs soaked in 4% lidocaine. Epiglottis, vocal cords, trachea and bronchi were anaesthetized by spraying 4% lidocaine through the working channel of the fiberoscope as the instrument was advanced. The patients in the propofol group were more sedated than those in the fentanyl+diazepam groups (P less than 0.01). The working conditions were the same. After sedation, respiratory frequency decreased only in the fentanyl+diazepam group (P less than 0.05). Before sedation, haemoglobin saturation of oxygen was 95 +/- 2% (mean +/- s.d.) in the propofol group and 94 +/- 3% in the fentanyl+diazepam group. Immediately before the start of bronchofiberoscopy, it was 89 +/- 4% and 90 +/- 3%, respectively. The decrease was statistically significant in both groups (P less than 0.001). After sedation, systolic arterial pressures (SAP) decreased in both groups (P less than 0.01). Compared to values immediately before starting bronchofiberoscopy, SAP increased during the procedure in both groups (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.     

Etomidate modifies hemodynamic response to fentanyl in patients with impaired left ventricular function]

The haemodynamic effects and the side-effects of anaesthesia using high doses of fentanyl were compared in two groups of 12 patients each. All the patients had poor left ventricular function and were scheduled for elective coronary artery bypass graft surgery or valvular replacement. Patients were randomly assigned to either group. In group EF, patients were given 5 micrograms.kg-1 of fentanyl, followed by 0.3 mg.kg-1 of etomidate. Once they had lost consciousness, they were given 15 mg of pancuronium and 25 micrograms.kg-1 of fentanyl over a 5 min period. Patients in group F received the full 30 micrograms.kg-1 dose of fentanyl over a 5 min period, followed by 15 mg of pancuronium. The patients were intubated 2 min after the end of the fentanyl infusion. They were mechanically ventilated with 100% oxygen. Anaesthesia was maintained with a continuous infusion of fentanyl (total dose 100 micrograms.kg-1). The usual haemodynamic parameters were monitored and calculated, as well as pain during injection of the drugs, myoclonia, chest wall rigidity and the time to loss of consciousness. The two groups were comparable with respect to age, weight, height and surgery. One third of the patients in group EF complained of pain during etomidate injection. The time required to loose consciousness was shorter in group EF (55 +/- 16 sec) than in group F (177 +/- 56 sec) (p < 0.001). The cardiac index decrease in group EF (2.0 +/- 0.4 l.min-1.m-2 vs. 1.9 +/- 0.4 l.min-1.m-2) (p < 0.05), respectively between the time just before tracheal intubation (T1), and 10 min after tracheal intubation (T3).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of alfentanil,fentanyl and enflurane as supplements to general anaesthesia for outpatient gynaecologic surgery

We compared two narcotic/N2O anaesthetic techniques and an inhalational anaesthesia/N2O technique for outpatient surgery in 59 women undergoing short gynaecological procedures. All patients received droperidol 0.625 mg IV, thiopentone and 70 per cent N2O in O2 plus either alfentanil (15 micrograms.kg-1), fentanyl (1.5 microgram.kg-1) or enflurane. The narcotics were given in a double-blind fashion and all anaesthetic techniques were assigned randomly. Cardiorespiratory parameters remained stable in all groups, with few clinically important changes occurring. Recovery was significantly faster in the group receiving alfentanil, with the time to respond to verbal commands and the time to establish alertness significantly faster than with either fentanyl or enflurane. All techniques provided satisfactory anaesthesia; however, the patients receiving alfentanil had significantly more adverse events than those receiving fentanyl.     

Dose requirements of vecuronium, pancuronium, and atracurium during orthotopic liver transplantation.

To further elucidate the role of the liver in the clearance of vecuronium, atracurium, and pancuronium, 30 patients undergoing orthotopic liver transplantation were randomly assigned to three comparable groups to receive a continuous infusion of vecuronium, atracurium, or pancuronium. The evoked integrated compound action potential of the hypothenar eminence in response to train-of-four ulnar nerve stimulation was measured and recorded. Anesthesia was induced with 3-5 mg/kg of thiopental, 50 micrograms/kg of midazolam, and 1-5 micrograms/kg of fentanyl IV and was maintained with continuous infusions of midazolam and fentanyl while the lungs were ventilated with an air-oxygen mixture. The infusion rates of vecuronium, atracurium, and pancuronium were adjusted to achieve a T1/Tc ratio of between 0.02 and 0.10 (T1 = height of first twitch, Tc = height of control twitch). Vecuronium and pancuronium requirements, which were 0.072 +/- 0.022 and 0.042 +/- 0.015 mg.kg-1.h-1 (mean +/- standard deviation) respectively during the dissection phase, decreased significantly during the anhepatic phase to 0.036 +/- 0.021 and 0.018 +/- 0.012 mg.kg-1.h-1 and returned toward the initial values in the postreperfusion phase (0.055 +/- 0.018 and 0.032 +/- 0.012 mg.kg.-1.h-1); whereas atracurium requirements remained unchanged during the three phases (0.667 +/- 0.199, 0.567 +/- 0.142, and 0.692 +/- 0.254 mg.kg-1.h-1). These data suggest that the liver has an important role in the elimination of vecuronium and pancuronium, whereas the elimination of atracurium is unaltered during exclusion of the liver from the circulation.     

A comparison of enflurane with alfentanil anaesthesia for gynaecological surgery

Forty patients undergoing gynaecological surgery were randomly assigned to receive either alfentanil and thiopentone for induction of anaesthesia, followed by alfentanil-N2O/O2 (60%/40%) for maintenance of anaesthesia, or low-dose fentanyl and thiopentone, followed by enflurane-N2O/O2 (60%/40%). More patients given enflurane developed a tachycardia (P less than 0.03) and 20% decreases in systolic and diastolic blood pressure. Times to recovery were significantly shorter after alfentanil than after enflurane. Plasma concentrations of alfentanil during induction suggested that haemodynamic and catecholamine responses were either less than, or did not differ from, baseline levels when the plasma concentration of the drug exceeded 150 ng ml-1. At extubation and the beginning of spontaneous breathing, the plasma concentration was 278 +/- 129 ng ml-1. Values for pharmacokinetic parameters of alfentanil were as follows: clearance, 5.2 +/- 2.0 ml kg-1 min-1; volume of distribution, 0.63 +/- 0.20 1 kg-1; and elimination half-life, 96.9 +/- 52.5 min. Two patients who had extended surgery had significantly lower plasma clearance of alfentanil and increased half-life. The authors conclude that the alfentanil technique was preferable to maintenance with enflurane.     

Anesthesia for craniotomy: total intravenous anesthesia with propofol and alfentanil compared to anesthesia with thiopental sodium, isoflurane, fentanyl, and nitrous oxide

STUDY OBJECTIVE: To compare a total intravenous (IV) anesthetic technique based on propofol and alfentanil with a commonly used anesthetic technique for craniotomy. DESIGN: Open-label, randomized, clinical study. SETTING: Neurosurgical clinic at a university hospital. PATIENTS: Forty patients, aged 18 to 55 years, scheduled for brain tumor surgery. INTERVENTIONS: In 20 patients, anesthesia was induced with fentanyl and thiopental sodium and maintained with fentanyl, dehydrobenzperidol, isoflurane, nitrous oxide (N2O), and a thiopental sodium infusion. Twenty patients were anesthetized with a propofol loading infusion followed by a maintenance infusion at a fixed rate. In addition, alfentanil was administered as a loading bolus, followed by a variable-rate infusion, with additional doses as necessary to maintain hemodynamic stability. MEASUREMENTS AND MAIN RESULTS: A decrease in blood pressure (BP) after induction with thiopental sodium was followed by a significant increase in BP and heart rate (HR) during intubation. BP and HR did not change during the propofol loading infusion. However, the administration of alfentanil was followed by a similar decrease in BP with a return to baseline values during the intubation period. Return of normal orientation (7 +/- 5 minutes vs 27 +/- 23 minutes) and concentration (12 +/- 12 minutes vs 35 +/- 37 minutes) was shorter and more predictable for the propofol-alfentanil-treated patients than for the thiopental sodium patients. Maintenance propofol concentration (nine patients) was between 3 +/- 0.69 micrograms/ml and 3.36 +/- 1.17 micrograms/ml, while the concentration at awakening was 1.09 microgram/ml. Alfentanil concentration at extubation (nine patients) was 79 +/- 34 ng/ml. CONCLUSION: A total IV anesthetic technique with propofol and alfentanil is a valuable alternative to a more commonly used technique based on thiopental sodium, N2O, fentanyl, and isoflurane.     

Analgesia for appendectomy: comparison of fentanyl and alfentanil in children

During etomidate-N2O vecuronium anaesthesia for appendectomy, three groups of 13 children received fentanyl as a 10 micrograms.kg-1 loading dose and 2 micrograms.kg-1 increments in Group F, alfentanil as a 100 micrograms.kg-1 initial loading dose and either 20 micrograms.kg-1 increments in Group AB or 1 microgram.kg-1.min-1 continuous infusion in Group AI. On the basis of intraoperative heart rate changes, the opioid regimen was less efficient in Group AB (P less than 0.05). Based upon equianalgesic cumulative dosage, the alfentanil/fentanyl potency ratio was in the range of 1/10 to 1/13. The awakening time was similar in all groups, as were the duration of postoperative analgesia, the incidence of postoperative pain and the incidence of nausea and vomiting. We conclude that high-dose alfentanil is as efficient as fentanyl for intra and postoperative analgesia in children undergoing appendectomy.     

The enflurane-sparing effect of alfentanil in dogs

Some investigators believe that the dog is less sensitive than are humans to the anesthetic/analgesic actions of opioids. The alfentanil plasma concentration [ALF] vs anesthetic effect relationship has been determined for humans undergoing surgery. This study was designed to determine the [ALF] vs anesthetic relationship for alfentanil in the enflurane-anesthetized dog and thereby to provide data by which the [ALF] vs anesthetic effect relationships in the dog and in humans could be compared. Mongrel dogs (n = 10) were anesthetized with enflurane, and enflurane MAC (EMAC) was determined in each dog. After this, each dog received at least three incremental infusions of alfentanil using infusion rates of 0.625, 1.6, 8, 32, or 80 micrograms.kg-1.min-1. EMAC and [ALF] were determined during each infusion rate. There was a linear increase in [ALF] produced by incremental infusions of alfentanil (r = 0.999). Administration of alfentanil produced a dose-dependent reduction of EMAC up to a maximum of 72.5 +/- 3.7% (mean +/- SEM) at 32 micrograms.kg-1.min-1 ([ALF] = 960 +/- 86 ng/ml); a ceiling effect was evident. The degree of EMAC reduction (69%) produced by an infusion rate of 8 micrograms.kg-1.min-1 ([ALF] = 223 +/- 13 ng/ml) was not statistically different from the EMAC reductions produced by infusion rates of 32 (73% reduction at [ALF] = 960 +/- 86 ng/ml) or 80 micrograms.kg-1.min-1 (70% reduction at [ALF] = 2613 +/- 247 ng/ml) (P greater than 0.05). The relative potency of alfentanil was one-seventh to one-tenth that of fentanyl studied under identical conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anesthesia with high dosage fentanyl in coronary patients: effects of pretreatment with droperidol and diazepam]

The Authors have considered the effects of droperidol or diazepam treatments in patients undergoing high-dose fentanyl anesthesia in cardiac surgery. Twenty patients have been examined and divided in two groups: group A received droperidol (0.2 mg.kg-1) and group B diazepam (0.1 mg.kg-1) five minutes after fentanyl anesthesia induction (500 micrograms.min-1) to reach the "sleep dose". The diazepam pretreatment, as regards droperidol, reduces a dose of fentanyl necessary to obtain the conscience loss (21.5 +/- 2.5 micrograms.kg-1 vs 28 +/- 2.9 micrograms.kg-1). Hemodynamically the droperidol group is very stable, whereas the diazepam group shows certain myocardial depression and less protection at the OTI time.