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.     

Reducing the haemodynamic responses to laryngoscopy and intubation

The effects of alfentanil and fentanyl on controlling the haemodynamic responses to laryngoscopy and intubation have been compared. Five groups of ten patients were studied. Induction was with thiopentone 4 mg/kg. Thirty seconds later group 1 received 1 ml/20 kg saline, group 2 received 15 micrograms/kg alfentanil, group 3 received 30 micrograms/kg alfentanil and group 4 received 5 micrograms/kg fentanyl one minute before induction. Suxamethonium was given 60 seconds after induction and intubation of the trachea was performed 150 seconds after the start of induction. Heart rate and mean arterial pressure were recorded every minute throughout and compared with pre-induction control values. Control patients (group 1) showed significant increases associated with tracheal intubation in all haemodynamic variables. No increases were noted in groups receiving 30 micrograms/kg alfentanil or 5 micrograms/kg fentanyl. The heart rate, but not blood pressure, increased with intubation after 15 micrograms/kg alfentanil. The mean time to movement in 50% of the control patients was 7 minutes. In those given 15 and 30 micrograms/kg alfentanil it was 11 and 12 minutes respectively. In those given 5 micrograms/kg fentanyl it was greater than 15 minutes. Alfentanil is shown to reduce the cardiovascular responses to laryngoscopy and intubation and the effect appears to have a shorter duration than that of fentanyl.     

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)     

Influence of induction technique on intubating conditions after rocuronium in adults: comparison with rapid-sequence induction using thiopentone and suxamethonium

We have assessed the effect of anaesthetic technique on intubating conditions after rocuronium 0.6 mg kg-1 in four groups (n = 25 each) of unpremedicated patients in whom anaesthesia was induced with either thiopentone 5 mg kg-1 or propofol 2.5 mg kg-1 alone, or supplemented with alfentanil 20 micrograms kg-1. Fifty control patients were anaesthetized with thiopentone followed by suxamethonium. Laryngoscopy was commenced at 45 s. Overall intubating conditions after rocuronium were similar to those after suxamethonium (good and excellent > or = 96%) only when alfentanil was part of the induction regimen. However, intubation time was similar in all five groups and averaged 55 (SD 3.2) s, and the tube could be passed through open vocal cords within 70 s. After rocuronium the response of the diaphragm to intubation was more pronounced in the two groups of patients not receiving alfentanil (P < 0.0001) and in patients anaesthetized using propofol with alfentanil (P < 0.01) than in the control group. Opioids (in doses equivalent to alfentanil 20 micrograms kg-1) constitute an integral part of an induction regimen containing rocuronium 0.6 mg kg-1, regardless of whether or not thiopentone or propofol is used, in order to achieve overall intubating conditions similar to those after suxamethonium.      

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.     

Protection by fentanyl against cardiac dysrhythmias during induction of anaesthesia

The effect of fentanyl on electrocardiographic changes during anaesthetic induction was studied in 113 adults and 77 children. The adults were pretreated with fentanyl 1, 2 or 3 micrograms kg-1 and the children received fentanyl 1 or 2 micrograms kg-1 as pretreatment. The control groups received no pretreatment. Two minutes after the pretreatment, thiopentone 5 mg kg-1 was injected followed by succinylcholine 1.5 mg kg-1 before laryngoscopy and intubation. In control adults, ventricular ectopic beats (VEB) occurred in 26% of the patients whereas fentanyl in all doses totally prevented them. In children, the incidence of VEB was 22% in the control group whereas both doses of fentanyl prevented the occurrence of VEB. In any doses, fentanyl did not prevent the prolongation of QT interval after succinylcholine.     

The haemodynamic effects of bronchoscopy

The cardiovascular responses to bronchoscopy under general anaesthesia were investigated in 36 premedicated patients. Twelve patients acting as controls received a standard intravenous anaesthetic of intermittent thiopentone and suxamethonium. A further 24 patients were given either fentanyl 6 micrograms/kg or alfentanil 18 micrograms/kg intravenously, one minute prior to induction. There were significant rises in systolic arterial blood pressure (p less than 0.05) and in rate pressure product (p less than 0.05) in the patients in the control group, but these changes were not seen in those patients receiving either fentanyl or alfentanil. However, dysrhythmias and ST segment changes indicative of myocardial ischaemia were present in some patients in all three groups.     

Comparison of fentanyl, sufentanil, and alfentanil anesthesia in patients undergoing valvular heart surgery

The hemodynamic responses to anesthesia and surgery were studied in three groups of 20 patients undergoing valve replacement surgery. Anesthesia was induced with either fentanyl (75 micrograms/kg), sufentanil (15 micrograms/kg), or alfentanil (125 micrograms/kg). Pancuronium (8 mg) was given for muscle relaxation and the lungs were ventilated with oxygen/air (FIO2 = 0.5). Additional fentanyl (25 micrograms/kg) or sufentanil (5 micrograms/kg) was given before skin incision. Patients receiving alfentanil were given a continuous infusion at a rate of 0.5 mg X kg-1 X hr-1. Only mean arterial blood pressure (MABP) and systemic vascular resistance (SVR) changed significantly in response to anesthesia or surgery. MABP decreased on average 24.5 mm Hg (P less than 0.01) after induction of anesthesia with sufentanil in patients with mitral valve disease. MABP and SVR increased significantly (P less than 0.01) in patients with aortic valve disease receiving fentanyl. There were no other statistically significant changes within the groups. Four patients (two in the sufentanil group and one from each of the other groups) developed transient hypotension during induction of anesthesia. It is concluded that all three opioids can provide satisfactory anesthesia for patients having valve replacement surgery.     

Pretreatment with opioids

Pretreatment with small doses of fentanyl (100 micrograms) or alfentanil (300 micrograms) was found significantly to reduce the induction dose of thiopentone. Fentanyl 50 micrograms and alfentanil 150 micrograms also significantly reduced the onset time and increased the consistency of action of midazolam. Respiratory depression was not a problem when 50 micrograms fentanyl or 150 micrograms alfentanil were used.     

Alfentanil and fentanyl sedation in infants and small children during cardiac catheterization

Thirty patients aged 1-23 mth received either alfentanil or fentanyl for the induction and maintenance of IV sedation during cardiac catheterization following oral flunitrazepam premedication (0.1 mg.kg-1). Patients breathed spontaneously 30 per cent oxygen in air. Both alfentanil and fentanyl abolished all reaction to pain and discomfort with minimal haemodynamic and respiratory changes. Induction doses of alfentanil and fentanyl were 20 +/- 6 and 2.5 +/- 1.1 (mean +/- SD) micrograms.kg-1, respectively, and maintenance requirements 30 +/- 12 and 1.5 +/- 0.6 micrograms.kg-1.h-1, respectively. These requirements were comparable among younger and older as well as cyanotic and acyanotic patients. The IV sedation described adds an effective method to the armamentarium of an anaesthetist working in the cardiac laboratory.     

Clinical study on total intravenous anesthesia with droperidol, fentanyl and ketamine--1. Introduction

We have developed a new method of total intravenous anesthesia with droperidol, fentanyl and ketamine and have administered it to more than 400 surgical patients, ranging in ages from 4 to 80 years. Cardiac and neurosurgical patients were excluded. After establishing a routine monitoring, droperidol 0.06-0.1 ml.kg-1 was slowly given. After 5 minutes, fentanyl 1-2 micrograms.kg-1 and ketamine 1.0-1.5 mg.kg-1 were slowly administered intravenously. Trachea was intubated following intravenous succinylcholine. A total dose of 5-15 micrograms.kg-1 of fentanyl was given intravenously with a continuous infusion of ketamine 2 mg.kg-1.hr-1 during surgical procedure. Air and O2 (FIO2 0.30-0.35) were given and muscle relaxation was achieved with necessary dose of intravenous pancuronium or vecuronium and no inhaled anesthetic was given. Total intravenous anesthesia has many advantages such as no air pollution in the operating theatre, empty bowels, no organ (hepato-renal) toxicity, good peripheral perfusion and low cost, while this method has several disadvantages to overcome such as hypertension. There are many anesthetic agents for total intravenous anesthesia. However, sufentanil, alfentanil and propofol are not available. Droperidol, fentanyl and ketamine are the best combination for this purpose in Japan so far.     

Antagonism of fentanyl and alfentanil by intravenous plus subcutaneous naloxone

Twenty patients undergoing microlaryngoscopy were anaesthetized with thiopentone. Half received fentanyl supplementation (about 8.5 micrograms/kg) and the other half alfentanil (about 65 micrograms/kg). Both groups were given naloxone 0.4 mg intravenously plus 0.4 mg subcutaneously shortly after the procedure which lasted some 12 minutes. The degree of ventilatory depression was assessed by a CO2 rebreathing test. The ventilation at an end-tidal PCO2 of 8.0 kPa (V8.0) was noted, and the findings related to a control value obtained on the day before anaesthesia. In the fentanyl group, V8.0 was significantly (p less than 0.05) less one hour after naloxone than 15 minutes after, and remained significantly below the control value for the first 8 hours after microlaryngoscopy. A second peak in plasma fentanyl concentration was observed four hours postoperatively in three patients. Respiratory depression in the alfentanil group was less pronounced and of shorter duration than in the fentanyl group. Postoperative plasma alfentanyl concentration decreased progressively with time in every patient.     

Effect of the association propofol-alfentanil on bronchial resistances in asthmatic patients

The bronchial resistances in 17 patients scheduled for ENT surgery were studied during general anaesthesia carried out with propofol and alfentanil. There were nine controls, all free from any allergic pathology. The other eight had bronchial hyperreactivity, with clinical asthma (one or two crises a month) treated with bronchodilators. Two had a complete Fernand-Widal syndrome, and the remaining six documented allergic asthma. All the patients were premedicated with hydroxyzine 2 mg.kg-1 orally on the eve of surgery, and two hours beforehand. Those patients who were on bronchodilators were given their drugs as usual with the premedication. Because bronchial resistances were measured with the patient breathing spontaneously (forced oscillation technique), induction was carried out in two steps, first with propofol 1.5 mg.kg-1, followed, two minutes later, by alfentanil 7 micrograms.kg-1. Once the bronchial resistances had been assessed the patient was given a further 2 mg.kg-1 dose of propofol, and alfentanil 40 micrograms.kg-1. The patient was then intubated, and anaesthesia maintained with propofol 9 mg.kg-1.h-1, and alfentanil 15 micrograms.kg-1 every fifteen minutes. In all, bronchial resistances were measured on the day before surgery, after premedication but before the patient had been given any anaesthetic drug, two minutes after the first injection of propofol, two minutes after the first injection of alfentanil, and after extubation. There were no significant differences between the two groups. Despite the small number of patients included in this study, it would seem that hydroxyzine, propofol and alfentanil may be used safely in patients with hyperreactive bronchi.     

Gastric emptying after minor gynaecological surgery

Gastric emptying was measured using the paracetamol absorption method in 30 patients immediately after a general anaesthetic for minor gynaecological surgery and in 10 female controls. Anaesthesia was induced with either propofol alone, propofol and alfentanil (4.5 micrograms.kg-1) or propofol and fentanyl (1.4 micrograms.kg-1) and maintained with intermittent propofol and 66% nitrous oxide in oxygen. Gastric emptying was delayed significantly in all patient groups when compared with volunteers. However, the delay in gastric emptying was similar in the three patient groups.     

Comparison of nicardipine, diltiazem and verapamil for controlling the cardiovascular responses to tracheal intubation

We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. Verapamil and the three other drugs were administered 45 s and 60 s before the start of direct laryngoscopy, respectively, in a double-dummy design. Anaesthesia was induced with thiopentone 4 mg kg-1 i.v. and fentanyl 2 micrograms kg-1 i.v. Tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% isoflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after administration of thiopentone and vecuronium. Patients receiving saline exhibited significant increases in systolic and diastolic arterial pressures (AP), heart rate (HR) and plasma concentrations of catecholamines associated with tracheal intubation. The increase in AP was attenuated in patients treated with any calcium channel blocker. The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.      

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.     

Comparison of Haemodynamic Effects of Morphine and Fentanyl in Patients with Coronary Artery Disease

The haemodynamic effects of morphine (2.5 mg kg-1) and fentanyl (16.7 and 25 micrograms kg-1) were compared in patients undergoing coronary artery bypass surgery. Morphine or fentanyl in combination with pancuronium, nitrous oxide and a small dose of thiopentone produced some deterioration of myocardial performance. Both analgesics failed to block haemodynamic responses to noxious stimulation including tracheal intubation and sternotomy. Heart rate increased following tracheal intubation and systemic vascular resistance increased after sternotomy. However, the larger dose of fentanyl (25 micrograms kg-1) was accompanied by the smallest haemodynamic changes. Supplementary anaesthetic agents were often required to maintain haemodynamic stability during sternotomy. It is suggested here that larger doses of fentanyl, or the addition of other intravenous or inhalation anaesthetics might be employed for patients with severe coronary artery disease and good left ventricular function. On the other hand, in patients with poor left ventricular function, the myocardial depressant properties of thiopentone and nitrous oxide may be detrimental.     

Rapid tracheal intubation with propofol, alfentanil and a standard dose of vecuronium

We studied 60 ASA I patients with Mallampati grade 1 airways to compare emergency intubating conditions with either alfentanil 20 micrograms kg- 1, propofol 2.5 mg kg-1 and vecuronium 0.1 mg kg-1, or with thiopentone 5 mg kg-1 and suxamethonium 1 mg kg-1. Ease of laryngoscopy, vocal cord status and cough response were graded. The trachea of all patients was intubated; 83% of patients in the alfentanil-propofol-vecuronium group and 86% in the thiopentone-suxamethonium group were considered to have satisfactory intubating conditions at 60 s. We conclude that the combination of alfentanil 20 micrograms kg-1, propofol 2.5 mg kg-1 and vecuronium 0.1 mg kg-1 provided adequate conditions for rapid tracheal intubation.      

The influence of alfentanil on the intubating conditions after priming with vecuronium

The ability of alfentanil 15 micrograms kg-1 or 30 micrograms kg-1 to improve intubating conditions was studied in four groups of 25 ASA class 1 patients. Induction of anaesthesia was with thiopentone 5 mg kg-1. Neuromuscular blockade was induced with vecuronium using the priming principle. The priming dose, priming interval and intubating dose were 0.01 mg kg-1, 4 min, and 0.1 mg kg-1, respectively. Intubation was attempted 1 min after the intubating dose. Intubating conditions were judged unacceptable in about 30% of the patients belonging to the control groups. Alfentanil 15 micrograms kg-1, when administered 65 s before intubation, reduced the incidence of coughing and diaphragmatic movement (P less than 0.05) but did not reduce the incidence of overall unacceptable intubating conditions. Alfentanil 30 micrograms kg-1, however, reduced the incidence of vocal cord movement (P less than 0.005) as well as coughing and diaphragmatic movement (P less than 0.002). Alfentanil 30 micrograms kg-1 reduced the incidence of unacceptable intubating conditions from about 30% to 4% (P less than 0.02).     

Cardiovascular responses caused by the combination of lidocaine and vecuronium in the induction of general anaesthesia

Fentanyl, vecuronium and enflurane may cause bradyarrhythmias during anaesthesia. Lidocaine administered before endotracheal intubation may interact synergistically with these agents. In this randomized and double-blind study, lidocaine 1 mg kg-1 (24 patients) or saline (20 patients) was given, immediately after glycopyrrolate 5 micrograms kg-1, fentanyl 1.5 micrograms ml-1 and thiopentone 3-5 mg kg-1, together with vecuronium 0.1 mg kg-1 as a rapid i.v. injection to healthy (ASA 1) surgical patients. Enflurane 0.8% was included in the inhaled gases 10 min and enflurane 1.6% 25 min after lidocaine administration. The plasma concentrations of lidocaine rose to a mean level of 3.1 micrograms ml-1 (maximum 7.1 micrograms ml-1) which may affect the electrical conduction at various sites in the heart. There were no statistically significant differences in arterial blood pressures or heart rates during anaesthesia between the groups. The incidence of junctional rhythm was 7/24 patients in the lidocaine group and 5/20 patients in the saline group. Three patients in the lidocaine group, and two patients in the control group developed junctional rhythm immediately after intubation. The plasma concentrations of vecuronium were unaffected by lidocaine. The ratio of the unbound lidocaine to plasma protein bound lidocaine was at the expected level and did not differ significantly 2 and 10 min after the injection.