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PubMed2004

Fentanyl inhibits GABAergic neurotransmission to cardiac vagal neurons in the nucleus ambiguus.

Fentanyl citrate is a synthetic opiate analgesic often used clinically for neonatal anesthesia. Although fentanyl significantly depresses heart rate, the mechanism of inducing bradycardia remains unclear. One possible site of action is the cardioinhibitory parasympathetic vagal neurons in the nucleus ambiguus (NA), from which originates control of heart rate and cardiac function. Inhibitory synaptic activity to cardiac vagal neurons is a major determinant of their activity. Therefore, the effect of fentanyl on GABAergic neurotransmission to parasympathetic cardiac vagal neurons was studied using whole-cell patch clamp electrophysiology. Application of fentanyl induced a reduction in both the frequency and amplitude of GABAergic IPSCs in cardiac vagal neurons. This inhibition was mediated at both pre- and postsynaptic sites as evidenced by a dual decrease in the frequency and amplitude of spontaneous miniature IPSCs. Application of the selective micro-antagonist CTOP abolished the fentanyl-mediated inhibition of GABAergic IPSCs. These results demonstrate that fentanyl acts on micro-opioid receptors on cardiac vagal neurons and neurons preceding them to reduce GABAergic neurotransmission and increase parasympathetic activity. The inhibition of GABAergic effects may be one mechanism by which fentanyl induces bradycardia.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2006

Pharmacokinetic properties of fentanyl effervescent buccal tablets: a phase I, open-label, crossover study of single-dose 100, 200, 400, and 800 microg in healthy adult volunteers.

BACKGROUND: The fentanyl effervescent buccal tablet (FEBT) is designed to enhance the rate and extent of the absorption of fentanyl, an opioid, through the buccal mucosa. OBJECTIVES: The purposes of this study were to assess the dose proportionality of FEBT in healthy volunteers over the potential therapeutic dose range (100-800 microg) and characterize the pharmacokinetic (PK) profile of 4 doses (100, 200, 400, and 800 microg) of FEBT. METHODS: This Phase I, randomized, open-label, 4-period crossover study was conducted at Radiant Research, Honolulu, Hawaii. Healthy adult volunteers with intolerance to opioids were randomly assigned to receive 1 of 4 single-dose sequences of FEBT: 100, 200, 400, and 800 microg (selected to encompass the anticipated therapeutic dose range), with each successive administration separated by a washout period of >or=7 days. Naltrexone hydrochloride (50-mg tablet) was administered-15 and 3 hours before and 9 hours after FEBT administration to block opioid receptor-mediated effects of fentanyl. Plasma fentanyl concentrations were measured from venous samples obtained over 72 hours after FEBT administration. Early fentanyl exposure was assessed using AUC from time 0 to 0.75 hour (the median T(max) of the reference dose [100 microg]) (AUC(0-Tmax')). Adverse events (AEs) were monitored and recorded throughout the study by medically qualified personnel. RESULTS: Thirty-two subjects (26 men, 6 women; mean [SD] age, 29.3 [7.2] years [range, 19-44 years]; mean [SD] weight, 74.7 [10.7] kg) were enrolled. Median T was between 35 and 45 minutes after FEBT administration. AUC(0-infinity) and C(max) increased approximately linearly with increasing doses of FEBT. Mean plasma fentanyl concentrations decreased from C(max) in a biexponential manner at the 100- and 200-microg doses and decreased in a triexponential manner at the 800-mug dose. Despite the triexponential decrease in the mean profile observed with the 400-microg dose, a biexponential decrease was observed in approximately half of the individual profiles. AUC(0-Tmax') ranged from 0.09 ng x h/mL with the 100-microg dose to 0.52 ng x h/mL with the 800-microg dose. The most commonly reported AEs in the 100-, 200-, 400-, and 800-microg dose groups were as follows: application-site erythema, 3, 3, 4, and 3 subjects, respectively; nausea, 3, 2, 5, and 4 subjects; somnolence, 3, 2, 3, and 2 subjects; and headache, 3, 2, 1, and 4 subjects. None of the AEs were serious. CONCLUSIONS: In this study of the dose proportionality of FEBT in healthy volunteers, the PK profile of FEBT was characterized by a high early systemic exposure of fentanyl (0.09-0.52 ng x h/mL). Dose-dependent parameters (C(max) and AUC) increased in an approximately dose-proportional manner from 100 to 800 microg FEBT.

Administration, Buccal↗
PubMed2003

Comparative effects of propofol versus fentanyl on cerebral oxygenation state during normothermic cardiopulmonary bypass and postoperative cognitive dysfunction.

BACKGROUND: The purpose of this study was to examine the comparative effects of propofol and fentanyl on cerebral oxygenation during normothermic cardiopulmonary bypass and postoperative cognitive dysfunction. METHODS: One hundred eighty patients scheduled for elective coronary artery bypass grafting were randomly divided into two groups: propofol group (n = 90) and fentanyl group (n = 90). After induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor jugular venous oxygen hemoglobin saturation continuously. Hemodynamic measurements and arterial and jugular venous blood gases were measured at seven time points. All patients underwent a battery of neurologic and neuropsychological tests on the day before the operation and at 6 months after the operation. RESULTS: Cerebral desaturation (defined as a jugular venous oxygen hemoglobin saturation value less than 50%) during cardiopulmonary bypass was more frequent in the fentanyl group than in the propofol group. Cerebral desaturation time (duration when jugular venous oxygen hemoglobin saturation was less than 50%) and the ratio of cerebral desaturation time to total cardiopulmonary bypass time in the fentanyl group differed significantly from those in the propofol group (fentanyl group: 27 +/- 14 minutes, 20% +/- 9%; propofol group: 18 +/- 11 minutes, 14% +/- 7%, respectively, p < 0.05). There was no significant difference in postoperative cognitive dysfunction at 6 months after operation between the two groups (propofol group: 5 of 77, 6%; fentanyl group: 5 of 75, 7%). CONCLUSIONS: Propofol preserved cerebral oxygenation state estimated by jugular venous oxygenation during cardiopulmonary bypass compared with the fentanyl group. However, propofol did not affect postoperative cognitive dysfunction.

Aged↗
PubMed2000

Chronic fentanyl treatments induce the up-regulation of mu opioid receptor mRNA in rat pheochromocytoma cells.

Chronic activation of adenylate cyclase-cAMP-cAMP-dependent protein kinase (PKA) systems by administration of opioid receptor agonists has been considered as one of the mechanisms of opioid tolerance and dependence. Although analysis of the micro opioid receptor (MOR) gene suggests that cAMP-related signal transduction systems regulate the expression of this gene, which transcription factors affect the MOR gene expression in brain and neural cells has not been clarified. This study deals with the effects of fentanyl on MOR mRNA levels in the rat pheochromocytoma cell line (PC12 cells). PC12 cells were cultured in medium with clinically relevant concentrations of fentanyl. The quantitative reverse transcription and polymerase chain reaction (RT-PCR) method was used for determination of MOR mRNA. Treatment of PC12 cells with fentanyl induced the MOR mRNA up-regulation in a concentration- and time-dependent manner. A cAMP analogue also up-regulated MOR mRNA. The intracellular cAMP level increased after fentanyl treatment. A PKA inhibitor blocked the MOR mRNA up-regulation by fentanyl and the cAMP analogue. Expression of a dominant inhibitory Ras also inhibited the MOR mRNA up-regulation. Fentanyl-induced up-regulation of MOR mRNA via activation of cAMP signaling may be important in compensating for the MOR reduction during long-term treatment of PC12 cells with fentanyl. The present study could be relevant to understanding the molecular mechanisms of opioids in a state of drug tolerance or dependence, and in patients under anesthesia or being treated for pain.

Analgesics, Opioid↗
PubMed1996

Routine use of fentanyl infusions for pain and stress reduction in infants with respiratory distress syndrome.

OBJECTIVE: To determine whether fentanyl infusions given to premature infants with respiratory distress syndrome reduce stress and improve long- and short-term outcome. METHODS: Twenty premature infants undergoing mechanical ventilation for respiratory distress syndrome were randomly assigned, in a double-blind fashion, to receive fentanyl by continuous infusion or a volume-matched placebo infusion. A behavioral state score was used to assess the infants' behavior. Cortisol and 11-deoxycortisol levels were measured as physiologic markers of stress. Urinary 3-methyl histidine/creatinine molar ratio was determined and the fractional excretion of urea was measured to assess catabolic state. Ventilatory indexes were recorded for each infant. RESULTS: Infants receiving fentanyl showed significantly lower behavioral state scores (p < 0.04) and lower heart rates (p < 0.001) than those receiving placebo. 11-Deoxycortisol levels were lower in the fentanyl group on days 3, 4, and 5 of the study (p < 0.003). 3-Methyl histidine/creatinine ratios and fractional excretion of urea were not significantly different between the two groups. On the third day of the study, infants receiving fentanyl required a higher ventilator rate (p < 0.01), higher peak inspiratory pressures (p < 0.001), and higher positive end-expiratory pressure (p < 0.0001) than those receiving placebo. There was no difference in long-term outcome with respect to the incidence of bronchopulmonary dysplasia, intraventricular hemorrhage, or sepsis or with respect to the duration of ventilator use. CONCLUSIONS: Although there was a reduction in stress markers in the infants receiving fentanyl, we were unable to demonstrate an improvement in catabolic state or long-term outcome. In addition, the infants receiving fentanyl required higher ventilatory support in the early phase of respiratory distress syndrome than did those receiving placebo.

Analgesics, Opioid↗
PubMed1999

Advantages of fentanyl over morphine in analgesia for ventilated newborn infants after birth: A randomized trial.

OBJECTIVE: To compare the efficacy and adverse effects of fentanyl or morphine analgesia during the first 2 days of life in newborn infants who underwent mechanical ventilation. STUDY DESIGN: In a randomized double-blind trial, 163 infants were allocated to receive a continuous infusion of fentanyl (10.5 microg/kg over a 1-hour period followed by 1.5 microg/kg/hr) or morphine (140 microg/kg over a 1-hour period followed by 20 microg/kg/hr) for at least 24 hours. The severity of pain was assessed with physiological parameters, a behavioral pain scale, and stress hormone concentrations before and 2 and 24 hours after the start of treatment. RESULTS: The analgesic effect was similar in both groups, as judged by the pain scale. Plasma adrenaline and noradrenaline concentrations decreased significantly from 0 to 24 hours in both groups. Median adrenaline decrease was 0.5 nmol/L (interquartile range [IQR] 1.1;0.0) in the fentanyl and 0.7 nmol/L (IQR 1.3;0.1) in the morphine group, noradrenaline 2.1 nmol/L (IQR 9.0;0.2), and 3.0 nmol/L (IQR 7. 5;0.3), respectively. beta-endorphin decreased significantly only in the fentanyl group ( 14 pmol/L (IQR 28; 7), P <.05). Decreased gastrointestinal motility was less frequent in the fentanyl group (23% vs 47%, P <.01). CONCLUSIONS: With at least as effective analgesia as with morphine, fentanyl had fewer side effects. Fentanyl may be superior to morphine for short-term postnatal analgesia in newborn infants.

Analgesics, Opioid↗
PubMed1987

Randomised trial of fentanyl anaesthesia in preterm babies undergoing surgery: effects on the stress response.

In a randomised controlled trial, preterm babies undergoing ligation of a patent ductus arteriosus were given nitrous oxide and d-tubocurarine, with (n = 8) or without (n = 8) the addition of fentanyl (10 micrograms/kg intravenously) to the anaesthetic regimen. Major hormonal responses to surgery, as indicated by changes in plasma adrenaline, noradrenaline, glucagon, aldosterone, corticosterone, 11-deoxycorticosterone, and 11-deoxycortisol levels, in the insulin/glucagon, molar ratio, and in blood glucose, lactate, and pyruvate concentrations were significantly greater in the non-fentanyl than in the fentanyl group. The urinary 3-methylhistidine/creatinine ratios were significantly greater in the non-fentanyl group on the second and third postoperative days. Compared with the fentanyl group, the non-fentanyl group had circulatory and metabolic complications postoperatively. The findings indicate that preterm babies mount a substantial stress response to surgery under anaesthesia with nitrous oxide and curare and that prevention of this response by fentanyl anaesthesia may be associated with an improved postoperative outcome.

Anesthesia, General↗
PubMed1998

The involvement of bulbospinal pathways in fentanyl-induced inhibition of spinal withdrawal reflexes in the decerebrated rabbit.

The selective opioid OP3(mu)-receptor agonist fentanyl was administered via the intravenous, intrathecal and intraventricular routes to decerebrated rabbits in doses from 1-30 microg/kg. Reflexes evoked in medial gastrocnemius motoneurones by electrical stimulation of the sural nerve were depressed by fentanyl given by all three routes. The opioid was most potent when given intrathecally and least potent when given into the fourth ventricle. Blockade of spinal alpha2-adrenoceptors by intrathecal RX 821002 (100 microg) reduced the effectiveness of intrathecal and low (<3 microg/kg) intravenous doses of fentanyl, but did not affect or enhanced responses to high intraventricular and intravenous doses. Spinalization reduced the effectiveness of intrathecal and intravenous fentanyl and abolished inhibition from intraventricular dosing. These data show that fentanyl acts in the spinal cord and in the brain stem to suppress spinal reflexes, although very high doses were required for effects from the latter site. It appears that low intravenous doses of fentanyl act mainly in the spinal cord and that increasing the dosage recruits descending inhibition. The results of alpha2-adrenoceptor blockade indicate that the spinal inhibitory effects of opioids are enhanced by an interaction with endogenous noradrenaline in the spinal cord. Thus, the full expression of the spinal inhibitory effects of fentanyl is dependent on brain stem cell groups, either as a source of noradrenaline input to the spinal cord, or as a site from which opioids can activate descending inhibitory systems.

Adrenergic alpha-Antagonists↗
PubMed1999

Simultaneous determination of fentanyl and midazolam using high-performance liquid chromatography with ultraviolet detection.

When measuring fentanyl and midazolam simultaneously in the same plasma sample with standard high-performance liquid chromatography-ultraviolet (HPLC-UV) detection, overlap of the fentanyl peak by the midazolam peak occurs, which makes fentanyl determination impossible. We tested the hypothesis that by acidifying the methanol mobile phase with 0.02% perchloric acid, 70%, it would be possible to separate both peaks. The UV detector was set at 200 nm. Calibration curves for fentanyl (range 0-2000 pg/ml) and midazolam (range 0-400 ng/ml) were linear (r>0.99). The detection limits were 200 pg/ml (fentanyl) and 10 ng/ml (midazolam). Precision and accuracy for intra- and inter-assay variability as well as in-line validation with quality control samples (QCS) were acceptable (<15 and 20%, respectively), except for fentanyl QCS of 200 pg/ml (17.8% precision). Although less sensitive than gas chromatography-mass spectrometry (GC-MS), reliable measurements of fentanyl, simultaneously with midazolam, can be performed with this HPLC-UV system.

Adjuvants, Anesthesia↗
PubMed2003

Preparation and in-vitro release rate of fentanyl-cyclodextrin complexes for prolonged action in epidural analgesia.

Fentanyl was complexed with cyclodextrin derivatives with the intention to obtain parenteral solutions able to provide prolonged analgesia following epidural administration. Three cylodextrins (CDs) suitable for parenteral use were used: hydroxypropyl-beta-cyclodextrin (HP-beta-CD), sulfobutylether-beta-cyclodextrin (SBE-7-beta-CD), and maltosyl-beta-cyclodextrin (malt-beta-CD). Analysis of fentanyl was done with HPLC-UV. The inclusion capacity of HP-beta-CD was determined from phase-solubility diagrams at pH 6.5, 7.2 and 8.0, and those of SBE-7-beta-CD and of malt-beta-CD at pH 8.0. Solubility of fentanyl increased linearly (i) as a function of the CD concentration, and (ii) with decreasing pH. Complexation was highest with HP-beta-CD and malt-beta-CD, much higher than with SBE-7-beta-CD, with stability constants at pH 8.0 of 801, 729 and 1309 M(-1), respectively. The CD concentration was calculated to obtain a fentanyl-CD formulation, with the desired amount free fentanyl as loading dose in solution and the rest complexed with CD, as reservoir for prolonged action. A suitable membrane and a release-rate apparatus were selected for in-vitro release-rate studies. Best results were obtained with Spectrapor membranes and a home-made release-rate apparatus. Release rate was evaluated in static and dynamic conditions. For both modes, the release rate of fentanyl decreased as a function of CD concentration, due to complex formation of fentanyl, which suggests the possibility to provide prolonged pharmacodynamic effects in vivo.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2002

[Rapid sequence intubation in emergency: is there any place for fentanyl?].

OBJECTIVES: Rapid sequence intubation (RSI) with the association of etomidate and succinylcholine is the French "Gold standard" for urgent "full stomach" endotracheal intubations. The aim of this study is to assess the fentanyl as a co-induction agent to take over the sedation between the RSI and the keeping of sedation, which is a critical period in which harmful neuro-vegetatives events, and awakening signs are frequently seen. STUDY DESIGN: Randomized, double blind controlled prospective study, after acceptation by the local ethical committee. PATIENTS AND METHODS: Three groups of patients undergoing RSI in the intensive care unit and by the out-of-hospital medical team were compared: group A patients received fentanyl 3 micrograms kg-1 during RSI, before paralysis was induced. Group B patients received the same dose of fentanyl immediately after endotracheal intubation. Group C patients did not received fentanyl (control group). Outcome measures were awakening signs arrival (respiratory movements, eyes opening, spontaneous limb movements), Ramsay score assessment, and haemody namics. Attempt at intubation and vomiting incident were also measured. Discrete data were compared by chi-2 analysis, continuous data were compared with two-way analysis of variance. A p value < 0.05 was the significant threshold. RESULTS: Thirty-six patients were enrolled and completed the study. All the included patients presented awakening signs. The use of fentanyl did not prevent the recourse of other sedative medications. Ten minutes after endotracheal intubation, significant differences has been noticed for the awakening signs arrival between fentanyl groups (A: 42% and B: 36%) and control group (C: 77%). The Ramsay score evolution follows the same variation. All the patients were intubated on the first attempt, there was no vomiting incident noticed. CONCLUSION: The use of fentanyl, as a co-induction agent with etomidate and succinylcholine during RSI, allows a significant delay of the awakening signs arrival and attenuate the neurovegetative response during the minutes after endotracheal intubation after RSI, without deleterious haemodynamic effects.

Anesthesia, Intravenous↗
PubMed1983

[Epidural anesthesia using the bupivacaine-fentanyl combination for cesarean section].

This prospective study was designed to evaluate the benefit of a bupivacaine-fentanyl mixture vs bupivacaine alone in epidural anaesthesia for caesarean section. In 10 women, 0.5% bupivacaine (1.18 ml per metamer) was injected in the epidural space. In 20 women, 0.5% bupivacaine (1.06 ml per metamer) was injected by the same route together with fentanyl (1.70 +/- 0.09 micrograms X kg-1). The bupivacaine-fentanyl group showed a significantly shortened onset of analgesia (p less than 0.001), as well as a significant reinforcement of this analgesia graduated from 0 to 4 (p less than 0.01 at 25 min, p less than 0.001 at 75 min and at the maximum of pain, for the two sets of scores). All the Apgar scores were maximal at 5 min. No clinical respiratory depression was observed in either the mothers or the neonates. Fetal and maternal blood concentrations were in favour of respiratory innocuousness of the method (peak fentanyl concentrations: in mothers 1.5 ng X ml-1, in neonates 0.8 ng X ml-1). Fentanyl never induced any significant haemodynamic variations. Pruritus and nausea respectively occurred in six and two patients respectively in the bupivacaine-fentanyl group. In conclusion, in caesarean section, the adjunction of fentanyl to bupivacaine significantly improved analgesia without any clinical respiratory depression both in the mother and the neonate.

Adult↗
PubMed1988

[Low-dose midazolam. Effect on the induction doses of fentanyl and on hemodynamics in the coronary patient].

A study was carried out to see whether the administration of a small dose of midazolam determined a reduction of the dose of fentanyl necessary for induction of anaesthesia. Sixteen patients undergoing coronary artery bypass surgery were randomly allocated to either of two groups. Patients in group M received 0.075 mg.kg-1 midazolam intravenously 3 to 5 min prior to induction with fentanyl (5 micrograms.kg-1.min-1), whereas patients in group P only received placebo. The mean dose of fentanyl administered to obtain complete loss of reaction to a painful stimulus was 20 +/- 3 micrograms.kg-1 in group M and 21.5 +/- 2.5 micrograms.kg-1 in group P (NS). However the small dose of midazolam associated with fentanyl caused a significant drop in blood pressure by 20%. After the administration of pancuronium (0.15 mg.kg-1), the patients in group P showed a significant increase in heart rate (+ 14 b.min-1), accompanied by an increase in cardiac index (+0.45 l.min-1.m-2). Pretreatment with midazolam seemed to protect the patient from this undesirable reaction. It was concluded that induction with a combination of a small dose of midazolam and fentanyl did not lead to a reduction in the dose of fentanyl necessary to obtain profound analgesia. However, it gave rise to a haemodynamic pattern quite distinct from that seen during induction with fentanyl alone.

Anesthesia, General↗
PubMed2002

Care of the dying: is pain control compromised or enhanced by continuation of the fentanyl transdermal patch in the dying phase?

The introduction of fentanyl transdermal patches has led to concern and confusion regarding the management of pain control in the dying phase. Data were collected retrospectively from 94 dying patients. Two groups were identified-patients treated with fentanyl transdermal patch who remained on the patch in the dying phase and patients on oral morphine who converted to a 24-hour subcutaneous infusion of diamorphine via a syringe driver in the dying phase. Both the fentanyl group and the diamorphine group had good pain control in the last 48 hours of life. During the last 48 hours of life, the proportion of patients with controlled pain was statistically significant in favor of the fentanyl group in 2 of the 12 observations undertaken, in particular whether the fentanyl transdermal patch should be continued or discontinued. Patients in the fentanyl group received fewer "as required" opioid doses compared to patients in the diamorphine group, although the difference was statistically significant only for the last day of life. This study showed that pain control was not compromised in the dying phase with continued use of the fentanyl patch.

Administration, Cutaneous↗
PubMed2003

Effects of fentanyl on pain and hemodynamic response after retrobulbar block in patients having phacoemulsification.

PURPOSE: To determine the effects of systemic fentanyl analgesia in preventing the pain related to the administration of retrobulbar anesthesia and cataract surgery. SETTING: Departments of Ophthalmology and Anesthesiology, School of Medicine, Kocatepe University, Afyon, Turkey. METHODS: One hundred twenty patients with American Society of Anesthesiologists physical status I to III scheduled for cataract surgery were evaluated in a single-blind randomized study. Patients with a history of hypertension, hyperthyroidism, or neurologic or psychiatric disorders were excluded. In the study (fentanyl) group, an intravenous bolus of fentanyl 2 microg/kg was slowly given 5 minutes before retrobulbar anesthesia was administered. In the control group, fentanyl was not given. There were 60 patients in each group. Demographic data were not statistically different between the 2 groups. The intensity of pain during injection and intraoperatively was measured by verbal pain scores. Hemodynamic stability was assessed by the heart rate (HR) and mean arterial pressure (MAP). End-tidal carbon dioxide concentrations and oxygen saturations were also recorded. RESULTS: The changes in HR and MAP at 0, 10, 20, and 30 minutes were statistically significant between the fentanyl and control groups (P<.05). Fentanyl reduced pain scores significantly at all evaluations (P<.05). CONCLUSION: The results suggest that fentanyl preemptively decreases injection and intraoperative hyperalgesia and provides hemodynamic stability without affecting patient cooperation, resulting in cataract surgery with retrobulbar anesthesia that is comfortable for both surgeon and patient.

Adult↗
PubMed2001

Does functional ability in the postoperative period differ between remifentanil- and fentanyl-based anesthesia?

STUDY OBJECTIVES: To compare patients' functional ability in the 24-hour postoperative period following a remifentanil compared to a hypnotic-fentanyl-treated anesthesia regimen using a 24-Hour Functional Ability Questionnaire. DESIGN: Prospective, 1:1 single-blind, randomized, controlled effectiveness study. SETTING: Multicenter study including 156 hospitals and ambulatory surgery facilities. PATIENTS: 2438 patients (1496 outpatients and 942 inpatients) 18 years of age or older, scheduled for elective surgeries under general endotracheal anesthesia, with an expected duration of unconsciousness of > or =30 minutes. INTERVENTIONS: Patients were randomized to receive either intravenous remifentanil (0.5 microg/kg/min for induction and intubation; with the infusion rate decreased to 0.25 microg/kg/min after intubation) or fentanyl (administered according to anesthesiologists' usual practice) as the opioid during surgery. Concomitant hypnotic drugs were propofol and/or isoflurane (with or without nitrous oxide) titrated according to protocol. Transition analgesia with either morphine or fentanyl was given in the remifentanil patients and at the discretion of the anesthesiologists in the fentanyl patients. MEASUREMENTS: A validated set of measurements of functional ability, rather than more traditional clinical psychological methods, to compare the recovery of patients from remifentanil- and fentanyl-treated anesthetic regimens up to 24 hours after surgery. MAIN RESULTS: Remifentanil was statistically superior to fentanyl for the four functional assessments evaluated: walking without dizziness, thinking clearly, concentration, and communicating effectively. These differences reflect events occurring within the first 24 hours after anesthesia and surgery. CONCLUSIONS: A remifentanil-treated anesthetic demonstrated earlier return to some functions than a fentanyl-treated technique. Although functional assessment is a field that is still in its infancy, a questionnaire to assess functional ability during the 24 hours after anesthesia may provide more practical information about anesthetic recovery than previously used, traditional psychomotor evaluations.

Analgesics, Opioid↗
PubMed2001

Hemodynamics and emergence profile of remifentanil versus fentanyl prospectively compared in a large population of surgical patients.

STUDY OBJECTIVE: To compare the responses to, and hemodynamics associated with surgical stress, recovery profiles, and anesthesiologists' satisfaction following balanced general anesthesia using either remifentanil or fentanyl in a large-scale population. DESIGN: Prospective, 1:1 single blind, randomized, controlled effectiveness study in which patients received either remifentanil or fentanyl in combination with a hypnotic-based anesthesia regimen of either isoflurane or propofol. SETTING: Multicenter study including 156 hospitals and ambulatory surgery facilities. PATIENTS: 2,438 patients (1,496 outpatients and 942 inpatients), 18 years of age or older, scheduled for elective surgeries under general endotracheal anesthesia, with an expected duration of unconsciousness > or =30 minutes. INTERVENTIONS: Patients were randomized to receive either intravenous (IV) remifentanil (0.5 microg/kg/min for induction and intubation, with the infusion rate decreased to 0.25 microg/kg/min after intubation) or IV fentanyl (administered according to anesthesiologists' usual practice) as the opioid during surgery. Concomitant hypnotic drugs were either propofol and/or isoflurane (with or without nitrous oxide) titrated according to protocol. Transition analgesia with either morphine or fentanyl was given to the remifentanil patients and, at the anesthesiologists' discretion, in the fentanyl patients. MEASUREMENTS: Vital signs, adverse events, and emergence profiles were assessed and recorded. Recovery profile was assessed by recording time spent in the postanesthesia care unit and step-down recovery unit, number and timing of adverse events, timing and dosage of rescue medications, and time to eligibility for discharge (to home or to hospital room). Anesthesiologists' satisfaction with the anesthetic regimen was assessed at the end of surgery. MAIN RESULTS: Remifentanil-treated patients exhibited lower systolic and diastolic blood pressures (by 10-15 mmHg) and lower heart rates (by 10-15 bpm) intraoperatively compared to the fentanyl-treated patients. This difference promptly disappeared on emergence. Remifentanil-treated patients responded to verbal command, left the operating room, and (for outpatients) were discharged home sooner than fentanyl-treated patients. Anesthesiologists rated the predictability of response to intraoperative titration, assessment of hemodynamic profiles, and the quality of anesthesia higher in the remifentanil-treated patients. CONCLUSIONS: This study confirms previous observations on the hemodynamic properties associated with remifentanil and extends these to a wider context than previously reported. These characteristics provide clinicians with an alternative in opioid-based anesthesia.

Adult↗
PubMed2003

The interaction between fentanyl and propofol during emergence from anesthesia: monitoring with the EEG-Bispectral index.

STUDY OBJECTIVE: To investigate the effect of different plasma levels of fentanyl on the concentration of propofol and the Bispectral Index (BIS) required for patients to regain consciousness and orientation following surgery. DESIGN: Prospective, open-label study. SETTING: Operating room of a university hospital. PATIENTS: 28 patients, aging 20 to 50 years, scheduled for elective, 1- to 4-hour surgeries under general anesthesia. INTERVENTIONS: BIS was continuously monitored from bifrontal montage (At1-Fpz and At2-Fpz) using an Aspect A-1,050 EEG system (Aspect, Natick, MA). Anesthesia was induced with bolus injections of fentanyl 2 microg/kg and propofol 2 mg/kg, and maintained with intermittent injections of fentanyl and constant infusion of propofol. Propofol infusion was stopped at the end of surgery. MEASUREMENTS: Consciousness and orientation were assessed as clinical endpoints once every 2 minutes following the end of the surgery. Blood samples were extracted for plasma propofol and fentanyl concentrations (PCp and FCp, respectively), and BIS values were recorded when patients regained consciousness and orientation. Patients were allocated to one of three groups depending on FCp on awakening: Group 1, FCp > 1 microg/L (n = 8); Group 2, FCp < 1 microg/L and >0.45 microg/L (n = 9); and Group 3, FCp < 0.45 microg/L (n = 11). PCp, BIS, recovery time, and other data were compared between the three groups. MAIN RESULTS: Demographic values, duration of surgery, and consumption of propofol and fentanyl were not different between the three groups. Group 3 patients regained consciousness with significantly higher propofol concentration (mean PCp = 3.2 mg/L) compared with those in Groups 1 and 2 (p < 0.05). However, the BIS values at both recovery endpoints were not different among the three groups. CONCLUSIONS: The plasma levels of fentanyl affect the concentrations of propofol required for patients to regain consciousness. The BIS values for wakefulness are unaltered at the different combinations of propofol and fentanyl concentrations. Thus, the BIS appears to be a useful and consistent indicator for level of consciousness during emergence from propofol/fentanyl intravenous anesthesia.

Adult↗