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.

A-3665, a new short-acting opioid: a comparison with alfentanil

A-3665 is a new short-acting synthetic opioid of the piperidine class. We conducted a double-blind, escalating dose comparison of A-3665 to alfentanil and placebo. Analgesic efficacy was assessed after the administration of A-3665 in increasing intravenous doses (0.25, 0.5, 1, 2, 4, 8, 16, 32, and 64 micrograms/kg) to nine groups of volunteers. At the lower doses (0.25, 0.5, 1, and 2 micrograms/kg), five volunteers were in each group; four received A-3665 and one received placebo in a double-blind manner. There were nine volunteers in each of the next three groups; four received A-3665 (4, 8, or 16 micrograms/kg), four received alfentanil (4, 8, or 16 micrograms/kg), and one received placebo. At the 32 micrograms/kg and 64 micrograms/kg dose levels, five subjects each were to be enrolled (four to receive A-3665 and one to receive placebo); however, the study was terminated after two subjects in the 64 micrograms/kg group had significant respiratory depression. Both drugs caused potent analgesia, compared with placebo, with peak effect occurring 3 min after injection. There was no significant difference in analgesic potency of A-3665 and alfentanil as measured by tolerance to tibial pressure at 3 min. At the dose of 16 micrograms/kg, both drugs significantly increased pain tolerance to tibial pressure compared with placebo at 3 min, but alfentanil continued to display significant analgesic effect versus placebo and versus A-3665 at 6, 11, and 15 min after injection. A-3665 caused significant respiratory depression at doses of 32 micrograms/kg and 64 micrograms/kg, but alfentanil did not induce significant respiratory depression at the doses tested.(ABSTRACT TRUNCATED AT 250 WORDS)

A system approach to pharmacodynamics. Input-effect control system analysis of central nervous system effect of alfentanil

Virtually all biological variables, including those affected by drugs, are subject to adaptive self regulation. In the description of the pharmacodynamics (PD) of drugs, it may be necessary to consider the endogenous control system (ECS) as an integral part of the PD. A PDECS model based on system analysis principles is presented and tested on PD data for alfentanil considering the central nervous system activity quantified by a power spectrum analysis of the electroencephalogram. The model was tested in terms of a proposed relative prediction performance criterion that measures the accuracy of future predictions relative to how well the model describes (fits) the past effect data. A mean value of 80% (standard deviation, 28) for relative prediction performance indicates that the model performs well when challenged by the complex multiple infusion scheme used in the test. The overshoot phenomenon observed in the data is considered by the PDECS model as a ECS-based tolerance phenomenon. The proposed development of tolerance is modeled as a variable gain in the ECS processing that influences the effect. Although the development and loss of tolerance is determined by a single rate constant in the tolerance model, the rates of increase and decrease of tolerance may be substantially different. Contrary to other PD tolerance models, the proposed PDECS approach models the tolerance in terms of an effect deviation from an ECS set point. The intrinsic (no tolerance) effect of the drug is isolated in terms of an open loop (no feedback) effect.

Unexplained hypertension during induction of a patient with phaeochromocytoma

An unexplained hypertensive response during the induction of anaesthesia for phaeochromocytoma resection is described. This response was not accompanied by elevations in plasma catecholamine levels. It occurred despite heavy premedication and followed induction with etomidate, alfentanil, lignocaine, vecuronium and magnesium sulphate (MgSO4). A bolus of esmolol (0.5 mg/kg) lowered the blood pressure rapidly. Subsequent haemodynamic manipulations were carried out by varying the rate of an esmolol infusion. A constant background infusion of MgSO4 was maintained throughout the procedure. These produced satisfactory haemodynamic control despite marked rises in plasma catecholamine levels.

Propofol and alfentanil in children: infusion technique and dose requirement for total i.v. anaesthesia

We estimated the dose of propofol (initial dose followed by a stepped infusion) when given with two different infusion rates of alfentanil for total i.v. anaesthesia in 59 children aged 3-12 yr. Patients in series 1 (four groups) received an alfentanil loading dose of 85 micrograms kg-1 and an infusion of 65 micrograms kg-1 h-1. Patients in series 2 (groups 5 and 6) received an alfentanil loading dose of 65 micrograms kg-1 and infusion of 50 micrograms kg-1 h-1. Parents gave their informed consent. Premedication comprised temazepam 0.3 mg kg-1. Glycopyrronium 5 micrograms kg-1 was administered and anaesthesia induced and maintained with alfentanil (loading dose and infusion) followed by propofol (loading dose and three-stage manual infusion scheme). Suxamethonium 1 mg kg-1 was used to facilitate tracheal intubation and the lungs were ventilated artificially to normocapnia with 30% oxygen in air. Probit analysis was used to determine the dose requirement of propofol. In series 1, the ED50 was 6.0 mg kg-1 h-1 (95% confidence limits 5.5-6.2 mg kg-1 h-1) and ED95 8.6 (6.8-7.8) mg kg-1 h-1. Corresponding values for series 2 were ED50 7.5 (8.0-9.8) mg kg-1 h-1 and ED95 10.5 (9.6-13.1) mg kg-1 h-1.

Ondansetron does not affect alfentanil-induced ventilatory depression or sedation

Ondansetron is a selective 5-hydroxytryptamine type 3 receptor antagonist effective as an antiemetic in patients experiencing post-operative or cancer chemotherapy-induced nausea and vomiting. Currently, no information is available regarding the interaction of ondansetron with opioids, although a serotonin antagonist might be expected to modify some opioid actions. This study was designed to measure the effects of ondansetron on alfentanil-induced ventilatory depression and sedation in healthy male volunteers. Ventilatory drive (measured as the end-tidal CO2 necessary to produce a minute ventilation of 15 l/min) was determined in 29 subjects using a modification of the Read rebreathing technique. Sedation was measured by asking the subjects to complete visual analog scales. Alfentanil was administered as a bolus (5 micrograms/kg) followed by a continuous infusion (0.25-0.75 micrograms.kg-1.min-1) for at least 90 min. Study medication (ondansetron 8 or 16 mg or vehicle placebo) was then administered in a randomized, double-blind manner, and the alfentanil was infused for an additional 15 min. Measurements of ventilatory drive and sedation were made at baseline, during alfentanil infusion, after study medication, and at 30-min intervals after alfentanil was discontinued. Alfentanil produced significant ventilatory depression (P less than 0.001) and sedation (P less than 0.001) in all three groups. Neither placebo nor ondansetron produced further change in the intensity of either alfentanil effect. After discontinuation of the opioid, both ventilatory depression and sedation decreased, and the rate of recovery was not significantly different between groups. The data indicate that alfentanil-induced sedation and ventilatory depression are not significantly affected by the subsequent administration of ondansetron.

Alfentanil-induced rigidity in newborn infants

The authors evaluated whether alfentanil could be given before treatment procedures in critically ill mechanically ventilated neonates without adverse effects. Alfentanil (mean dose 11.7 micrograms/kg, range 9-15) was given intravenously to 20 mechanically ventilated critically ill newborn infants (mean birth weight 2510 g, range 1490-3990) during the first 3 days of life before treatment procedures. Heart rate, arterial blood pressure, transcutaneous partial pressure of O2, respiratory rate, and general activity were observed continuously from 10 min before the administration of alfentanil until 1 h after it. Plasma alfentanil concentrations were measured in 15 subjects. The pharmacokinetics of alfentanil varied greatly among the subjects. The hemodynamic changes were not clinically significant, and the most important side effect was muscle rigidity. Nine infants had mild or moderate rigidity, which had little or no effect on ventilation. Four infants had severe rigidity and jerking comparable to convulsive activity, transiently impairing ventilation and oxygenation for approximately 5-10 min. Increased inspired oxygen and increased pressure by manual ventilation were needed to prevent hypoxemia. Electroencephalographic recordings for three infants during alfentanil administration showed no evidence of increased seizure activity. We conclude that alfentanil should not be used for newborn infants without simultaneous muscle relaxation because of the danger of rigidity.

Intraoperative patient-controlled analgesia: an alternative to physician administration during outpatient monitored anesthesia care

Outpatients undergoing minor diagnostic and therapeutic procedures associated with intermittent discomfort are frequently given bolus injections of intravenous opioid analgesics. In a group of 80 healthy women undergoing vaginal ovum pickup procedures, we evaluated patient-controlled administration of alfentanil using a patient-controlled analgesia device (with a lockout interval of 3 min) as an alternative to conventional physician-controlled administration. The two alfentanil administration techniques were equally effective in providing intraoperative analgesia. The average alfentanil dosage requirements were 1.49 +/- 0.50 and 1.46 +/- 0.55 micrograms.kg-1.min-1 (mean +/- SD) in the physician- and patient-controlled groups, respectively. The incidence of postoperative nausea was the same in both treatment groups (8%). Even with the mandatory lockout interval, intraoperative patient-controlled administration of alfentanil was comparable to physician-controlled administration with respect to patient comfort and satisfaction during vaginal ovum pickup procedures.

[The effect of nitrous oxide anesthesia combined with low dose alfentanil for minor surgery of short duration]

This study was conducted in 30 adult patients with ASA class I-II physical status who received minor operations. Anesthetic induction was achieved by injecting thiopental 4 mg/kg intravenously in addition to N2O/O2 (4L/2L) delivered via Ventri Mask, followed by alfentanil 7 micrograms/kg intravenously 3 min later. Maintenance of anesthesia was accomplished by N2O/O2 in conjunction with alfentanil 0.25-2.5 micrograms/kg/min, delivered intravenously by a syringe pump. Our result showed that in an operation of average duration around 40.2 +/- 10.5 min., the average dose of alfentanil used was 0.62 +/- 0.15 micrograms/kg/min. The respiration rate fell from 13.4 +/- 0.4 cpm to 8.4 +/- 1.1 cpm 2 min later following alfentanil injection, which was statistically significant. SaO2 fell from 97.9 +/- 0.4% to 94.0 +/- 0.8% 3 min after alfentanil injection, which was statistically significant. End-tidal carbon dioxide partial pressure elevated from 39.4 +/- 0.6 mmHg to a peak of 45.3 +/- 1.2 mmHg 5 min after alfentanil injection which was also statistically significant. Temporary apnea was noted in 3 cases, but they all resumed spontaneous respiration after a short period of assisted ventilation. Changes in systolic and diastolic pressure during anesthesia were not marked. Pulse rate was noted to decrease from 80.3 +/- 2.7 bpm to 70.5 +/- 2.0 bpm 1 min after alfentanil injection, which was statistically significant (p less than 0.05). After discontinuation of N2O, the time required to regain the ability to follow orders of "open your eyes," "show your thumb" and "say your name" in sequence was 72.5 +/- 10.6s, 88.2 +/- 11.6s, 128.1 +/- 23.0s, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Patient-controlled analgesic infusions: alfentanil versus morphine

Previously, we found that cancer patients using a pharmacokinetically based patient-controlled intravenous infusion system (PKPCA) to regulate their own morphine infusion rates achieved more relief from oral mucositis pain than similar patients using morphine by bolus-dose PCA. In this study, we employed the PKPCA system to compare efficacy and side-effect intensities of 2 mu-selective opioid analgesics, alfentanil and morphine, in bone marrow transplant (BMT) patients self-administering the drugs to relieve pain from oral mucositis. Patients using morphine by PKPCA obtained more pain relief than patients regulating their own alfentanil infusions during the first 4 days of continuous opioid infusion therapy. Side-effect intensities did not differ between the 2 study groups. In contrast to patients using morphine for 4-14 days, those receiving alfentanil by PKPCA required unexpectedly high plasma concentrations of the drug to obtain equivalent pain relief. Our results indicate that either the relative potencies of these 2 mu-selective opioids differ from previous estimates or analgesic tolerance developed to alfentanil but not to morphine. We conclude that alfentanil has similar efficacy in control of prolonged pain in BMT patients, but the utility of alfentanil in long-term pain management may be limited by relatively rapid tolerance onset.

The incidence of postoperative nausea and vomiting: a retrospective comparison of alfentanil versus sufentanil

Postoperative nausea and vomiting have been associated with the use of intravenous narcotics, and nitrous oxide may worsen the emetic effects of narcotics. Alfentanil and sufentanil are two synthetic derivatives of fentanyl; alfentanil has a shorter wake-up time than fentanyl, and sufentanil is equivalent to fentanyl. In order to study comparative emetic properties of these two drugs, patients in two different cities were randomly allocated to two different groups and retrospectively compared. Group I received sufentanil N2O/O2 with 0.25% isoflurane. Group II received alfentanil N2O/O2 with 0.25% isoflurane. With group I, the overall incidence of nausea was 31% and of vomiting was 6.2%. For group II, the overall rate for nausea was 38.2% and 8.8% for vomiting. Statistically, there was no significant difference in nausea or vomiting between groups.

Alfentanil analgesia/sedation for extracorporeal shock wave lithotripsy: a comparison with general and epidural anesthesia

An alfentanil infusion was used to produce analgesia and sedation for patients undergoing extracorporeal shock wave lithotripsy with the Dornier HM-4 lithotripter. This was compared to general and epidural anesthesia in a retrospective review of 197 consecutive patients. Total care time, anesthesia time, and recovery room time were shorter for the alfentanil analgesia/sedation group. The incidence of nausea and vomiting was similar in all three groups. Technical failure (requiring switching to general anesthesia) was not significantly different than when performed with epidural anesthesia. The technique was simple and reliable when performed by a large number of anesthesia practitioners (anesthesiologists, anesthesia residents and CRNAs).

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.

Ventricular dysrhythmias following an alfentanil anesthetic in a patient on reserpine for hypertension

The case is presented of a hypertensive patient on reserpine, who developed ventricular irritability after administration of alfentanil, a new ultra-short-acting narcotic used in anesthesia. The dysrhythmias resolved after cessation of the offending agent. There are no reported cases of interaction of reserpine and alfentanil in the literature.

Propofol and alfentanil infusions for sedation in intensive therapy

Forty-four patients, with admission APACHE II scores between 5 and 24, undergoing mechanical ventilation in the intensive therapy unit, received a sedative regimen consisting of continuous infusions of propofol and alfentanil. Patients were randomly allocated to one of three groups to receive either alfentanil 0.25 microgram kg-1 min-1 (10 patients), 0.50 microgram kg-1 min-1 (15 patients) or 0.75 microgram kg-1 min-1 (18 patients) for analgesia. An infusion of propofol 20-200 mg h-1 ran concurrently to maintain a satisfactory level of sedation. Patients received the infusions for between 4 and 260 h and 38 patients spent more than 90% of this time at satisfactory sedation levels. After stopping the infusions all patients had short times to wakening (mean 3-18 min) and to establish spontaneous respiration (mean 8-28 min), suggesting no significant cumulation. Some depression of blood pressure was seen on starting the infusions, which was in general easily treated with fluids or small increases in inotropic agents. One patient, however, was withdrawn from the trial because of haemodynamic instability. This combination of drugs can be recommended for sedation of general intensive-therapy patients, provided the cost is not felt to be prohibitive.

Alfentanil for urgent caesarean section in a patient with severe mitral stenosis and pulmonary hypertension

We present the case of a parturient with severe mitral stenosis and pulmonary hypertension who received general anaesthesia using alfentanil for urgent Caesarean section. Alfentanil promoted haemodynamic stability and allowed immediate postoperative extubation. Epidural morphine provided postoperative analgesia. This combination permitted early ambulation and prevention of thromboembolism. A disadvantage of this technique, neonatal respiratory depression, was promptly reversed with a single dose of naloxone. The anaesthetic management of mitral stenosis in pregnancy is discussed and the neonatal pharmacokinetics of maternally administered alfentanil are presented.