EFFECT OF COMPETITIVE MYONEURAL BLOCKADE AND FENTANYL ON MUSCLE FASCICULATIONS CAUSED BY SUXAMETHONIUM IN CHILDREN

The effects of tubocurarine 0.06mg kg^–1, alcuronium 0.03mg kg^–1, pancuronium 0.01 mg kg^–1, and fentanyl1 or 2 µg kg^–1 on the muscle fasciculations associatedwith suxamethonium were studied in 171 children undergoing otolaryngologicalsurgery. The mean fasciculation index in all pretreatment groupswas significantly smaller than in the control group. The mosteffective pretreatment was fentanyl 2µg kg^–1 followed,in order, by alcuronium, fentanyl 1 µg kg^–1, tubocurarineand pancuronium. The rate of the onset of the fasciculationsafter the injection of suxamethonium ranged from 8 s after pancuroniumto 20 s after tubocurarine. There was evidence of respiratorydepression in the children receiving fentanyl 2 µg kg^–1if the duration of anaesthesia was less than 30 min.     

COMPARISON OF SUFENTANIL-OXYGEN AND FENTANYL-OXYGEN ANAESTHESIA FOR CORONARY ARTERY BYPASS GRAFTING

Haemodynamic variables were compared in 40 adults undergoingcoronary artery bypass grafting during anaesthesia induced witheither sufentanil 5 µg kg^–1 or fentanyl 25 µgkg^–1 in combination with pancuronium 0.1 mg kg^–1.Further doses of sufentanil 2.5 µg kg^–1 or fentanyl12.5 fig kg^–1 were given before skin incision and againbefore sternotomy. All patients were receiving ß-adrenoceptorblocking therapy. Satisfactory induction of anaesthesia wasproduced with both drugs and opioid supplementation preventedany marked haemodynamic response to skin incision and to sternotomy.Following induction of anaesthesia, sufentanil produced thegreater decrease in mean arterial pressure and left ventricularstroke work index which continued throughout the study. Thissuggests that, in the doses used in this study, sufentanil ispreferable to fentanyl in patients with coronary artery disease.     

PROPOFOL-FENTANYL ANAESTHESIA FOR CORONARY BYPASS SURGERY IN PATIENTS WITH GOOD LEFT VENTRICULAR FUNCTION

The haemodynamic effects of propofol-fentanyl anaesthesia forelective coronary bypass surgery were studied in 15 patientswith good left ventricular function. The induction dose of propofolwas 1. 5 mg kg^–1. The mean infusion rate during maintenancewas 5. 15 mg kg^–1 h^–1 (range 4. 05–8.82 mgkg^–1 h^–1). The total dose of fentanyl given in thepre-bypass period was 32µg kg^–1. Induction of anaesthesiawas associated with significant (P < 0. 05) decreases insystolic (–28% ) and diastolic (–23%) pressures,systemic vascular resistance (–25% ) and left ventricularstroke work index (LVSWI) (–32%). The decrease in LVSWI(P<0. 05) during induction and maintenance with unchangedfilling pressures, indicated myocardial depression. Clinicalsigns that could reflect myocardial ischaemia were not observedduring the operation. There were no changes in the concentrationsof the cardiac enzymes in the postoperative period and ECG morphologywas unchanged.     

EFFECT OF A NEW ANALEPTIC DRUG, ALMITRINE, ON FENTANYL-INDUCED RESPIRATORY DEPRESSION AND ANALGESIA IN MAN

Five female patients received fentanyl 0.0066 mg kg^–1i.v. (group A); five other female patients received the samedose of fentanyl, followed immediately by almitrine 0.5mg kg^–1i.v. (group B) and 20 minor gynaecological operations were performedunder a combination of almitrine 0.5mgkg^–1 and fentanyl0.0066 mg kg^–1 (groupC). In group A, fentanyl produceda marked and significant respiratory depression (P < 0.001).In group B and C, almitrine antagonized the fentanyl-inducedrespiratory depression. Analgesia did not seem to be affected.     

HAEMODYNAMIC EFFECTS OF VECURONIUM, PANCURONIUM AND ATRACURIUM IN PATIENTS WITH CORONARY ARTERY DISEASE

Thirty patients with ischaemic heart disease scheduled for coronaryartery bypass grafting were randomly allocated to three equalgroups. Following morphine, hyoscine and pentobarbi-tone premedication,anaesthesia was induced with diazepam 0.3 mg kg¹. Five minuteslater neuromuscular blockade was induced with pancuronium 0.1mg kg¹, vecuronium 0.1 mg^–1 or atracurium 0.5 mg kg^–1,followed after 6 min by fentanyl 25 µg kg^–1. Pancuroniumand atracurium caused significant increases in heart rate, whilevecuronium induced little change. Systemic vascular resistancedecreased significantly from 1515 dyn s cm^–6 to 1200 dyns cm^–5 following atracurium. Cardiac index was increasedtransiently in the atracurium group, but a more sustained increasewas observed following pancuronium. Nine patients in the atracuriumgroup showed skin flushing and one developed skin weals.     

Propofol and fentanyl anaesthesia for patients with low cardiac output state undergoing cardiac surgery: comparison with high-dose fentanyl anaesthesia

We have compared the haemodynamic effects of an infusion ofpropofol 8mg kg^–1 h^–1 followed by 4mg kg^–1h–1 and fentanyl 15µg kg^–1 (group 1) withmidazolam 3–6mg and fentanyl 60 µg kg^–1 (group2) in patients with a low cardiac output state undergoing cardiacsurgery. Heart rate was lower in group 1 throughout the periodbefore cardiopulmonary bypass. There were no significant differencesbetween the groups in other measured variables. Arterial pressuredecreased in both groups after induction, by 21% in group 1and 18% in group 2. Thermodilution assessment of right ventricularejection fraction was unchanged. Myocardial contractility wasnot affected adversely. Patients in group 1 who received aninfusion of propofol and a smaller dose of fentanyl awakenedsooner and the trachea was extubated earlier.     

Comparison of the haemodynamic effects of mivacurium and atracurium during fentanyl anaesthesia

We have measured the haemodynamic effects of mivacurium 0.15and 0.2 mg kg^–1, and atracurium 0.5 mg kg^–1 administeredover 10–15 s in patients undergoing coronary artery bypasssurgery under fentanyl anaesthesia. There were no significanthaemodynamic changes in the atracurium group, other than a transientdecrease in pulmonary arterial wedge pressure. Changes in heartrate were small in all three groups. Mivacurium 0.15 mg kg^–1produced changes of only small magnitude (12% decrease in meanarterial pressure and 16% decrease in systemic vascular resistanceindex) however, mivacurium 0.2 mg kg^–1 produced a 25%reduction in mean arterial pressure, a 14% increase in cardiacindex and a 35% decrease in systemic vascular resistance index.Erythema developed in two, three and seven patients after atracurium,mivacurium 0.15mgkg^–1 and mivacurium 0.2 mg kg^–1,respectively. One patient exhibited a 54% decrease in mean arterialpressure, generalized erythema and bronchospasm after mivacurium0.2mg kg^–1. The haemodynamic changes with mivacurium suggestedhistamine release. (Br. J. Anaesth. 1995; 74: 330–332)     

INTERACTION OF KETAMINE WITH ATRACURIUM

The effect of ketamine on the duration of atracurium-inducedneuromuscular blockade was studied in 40 healthy patients anaesthetizedwith midazolam, fentanyl and nitrous oxide. Twenty received,in addition, i.v. ketamine 2 mg kg^–1 followed by an infusionof 2 mg kg^–1 h^–1. Atracurium 0.5 mg kg^–1 wasinjected i.v. and the time to 25% recovery of the twitch heightwas measured. It was 8.0 min longer in the ketamine group (P< 0.005), with a 95% confidence interval of from 2.3 to 11.8min.     

VECURONIUM INDUCED BRADYCARDIA FOLLOWING INDUCTION OF ANAESTHESIA WITH ETOMIDATE OR THIOPENTONE, WITH OR WITHOUT FENTANYL

To define the role of vecuronium in the occurrence of bradyarrhythmia,haemodynamic changes after the induction of anaesthesia werestudied in 96 patients undergoing coronary artery bypass grafting.Patients were assigned to one of six groups according to differentcombinations of induction agents (etomidate 0.3 mg kg^–1or thiopentone 3 mg kg^–1, with fentanyl 0.003 mg kg^–1,etomidate 0.4–0.5 mg kg^–1 or thiopentone 4–6mg kg^–1, without fentanyl) and neuromuscular blockingdrugs (vecuronium 0.112 mg kg^–1, pancuronium 0.112 mgkg^–1 or suxamethonium 1 mg kg^–1). Anaesthesia wasmaintained with enflurane and nitrous oxide in oxygen. Afterinitial diverse changes, heart rate decreased in all groups.Thirty minutes after intubation, the reduction of heart rateshowed statistically significant differences between the differentcombinations of drugs: fentanyl–etomidate–vecuronium(group I) (the largest reduction) > etomidate–vecuronium(II) = fentanyl–thiopentone–vecuronium (IV) >thiopentone–vecuronium (V) = fentanyl–thiopentone–suxamethonium(VI) = fentanyl–etomidate–pancuronium (III). Fivepatients in group I, two in group IV and one each in groupsII and V had a heart rate slower than 45 beat min^–1, whereasa similar value was never seen in groups III and VI. These resultsindicate that vecuronium has a bradycardic effect. This effectis more pronounced in association with etomidate than in associationwith thiopentone, and is augmented by the addition of fentanyl.     

COMPARISON OF ETOMIDATE IN COMBINATION WITH FENTANYL OR DIAZEPAM, WITH THIOPENTONE AS AN INDUCTION AGENT FOR GENERAL ANAESTHESIA

In 104 premedicated patients undergoing general surgery, anaesthesiawas induced either with etomidate 0.3 mg kg^–1 precededby fentanyl 1.25 or 2.5 µg kg^–1 i.v. or diazepam0.0625 or 0.125 mg kg^–1 i.v., or with thiopentone precededby fentanyl 1.25 µg kg^–1 i.v. Despite the use offentanyl or diazepam, the frequency of pain on injection inpatients receiving etomidate was between 32% and 53%, beingrated as severe in 5–20% of patients. No pain was experiencedby patients receiving thiopentone. The frequency of involuntarymovement was 15–35% with etomidate and 15% with thiopentone.The frequency of both pain and involuntary muscle movementswas least when fentanyl 2.5 µg kg^–1 preceded theadministration of etomidate. There was no significant relationshipbetween the pain and muscle movement; three of 10 patients givenetomidate into a central vein had such movements. ^*Present address: Department of Anesthesia, University of lowaHospitals and Clinics, lowa City, IA 52242, U.S.A.     

EFFECTS OF INCREASING DOSES OF ALFENTANIL, FENTANYL AND MORPHINE ON MID-LATENCY AUDITORY EVOKED POTENTIALS

We have studied dose-dependent effects of alfentanil, fentanyland morphine on mid-latency auditory evoked potentials (MLAEP).Anaesthesia was induced with alfentanil 100 µg kg^–1every 5 mm to a total dose of 500 µg kg^–1 (groupI, n = 10), fentanyl 10 µg kg^–1 every 7 min to atotal dose of 50 µg kg^–1 (group II, n = 10) or morphine1 mg kg^–1 for induction and 0.5 mg kg^–1 every 15min to a tota l dose of 3mg kg^–1 (group III, n = 10).MLAEP were recorded before and 3–15 min after every opioiddose on vertex (positive) and mastoids on both sides (negative).Latencies of the peaks V, Na, Pa, Nb, P1 (ms) and amplitudesNa/Pa, Pa/Nb and Nb/P1 (µV) were measured. Fast-Fouriertransformation was used to calculate power spectra of the AEP.In the awake state, MLAEP had high peak-to-peak amplitudes anda periodic waveform. Power spectra indicated high energy inthe 30–40 Hz frequency range. During general anaesthesiawith increasing doses of alfentanil, fentanyl and morphine,the brainstem response V was stable. There was a marked increaseonly in latency and decrease in amplitude of P1. In contrast,for the early cortical potentials Na and Pa, only small increasesin latencies and decreases in amplitudes were observed. Afterthe largest doses of affentanil (500 µg kg^–1), fentanyl(50 µg kg^–1) and morphine (3 mg kg^–1) Na,Pa and Nb showed a similar pattern as in awake patients. Inthe power spectra, high energy persisted in the 30-Hz frequencyrange. There were no dose-dependent effects of opioids on MLAEPand no differences between alfentanil, fentanyl, and morphinecould be found. (Br. J. Anaesth. 1993; 71: 622–628)     

DICLOFENAC FOR DAY-CARE ARTHROSCOPY SURGERY: COMPARISON WITH A STANDARD OPIOID THERAPY

Sixty unpremedicated patients presenting for day-care arthroscopysurgery were allocated randomly to receive diclofenac 1 mg kg^–1i.m., fentanyl 1 µg kg^–1 i.v. or no analgesic duringthe course of anaesthesia. Patients receiving fentanyl had slightly,although not significantly prolonged recovery times. Patientsreceiving diclofenac had significantly improved postoperativevisual analogue pain scores compared with patients receivingplacebo medication (P < 0.05). With fentanyl, pain scoreswere reduced also, but the effect was not statistically significant.Both fentanyl and diclofenac produced significant reductionin postoperative analgesic requirements (P < 0.05). We concludethat diclofenac 1 mg kg^–1 i.m. was an effective analgesicfor arthroscopic procedures on the knee and is a useful alternativeto opioids for day-care patients.     

Postoperative extradural analgesia in children: comparison of morphine with fentanyl

We have compared the efficacy and side effects of extraduralmorphine with extradural fentanyl for postoperative pain relief.Thirty children (ages 1–16 yr) were allocated randomlyto receive, after extradural administration of 0.5% bupivacaine0.75 ml kg^–1 and before surgical incision, extreduralmorphine 0.75 µg kg^–1 (group M), with an additionaldose administered 24 h later or extradural fentanyl 2 µgkg^–1 (group F) followed by a continuous extradural infusion(during 48 h). There was no major complication (respiratorydepression). Pain scores were satisfactory in both groups for48 h. Ventilatory frequency was greater in group M 20, 21, 22,23 and 25 h after the beginning of analgesia (P < 0.05).Pruritus, nausea and vomiting were less common with extraduralfentanyl (20% vs 53%, P < 0.05 and 0% vs 33%, P < 0.05)than with morphine. Urinary retention occurred with equal frequency(25%) in the two groups. After a bolus of 2 µg kg^–1,continuous extradural infusion of fentanyl 5 µg kg^–1day^–1 provided analgesia comparable to that from a dailybolus of extradural morphine 0.75 mg kg^–1 and producedfewer side effects.      

A fine balance--one-lung ventilation in a patient with Eisenmenger syndrome

A 38-yr-old woman with an atrial septum defect and Eisenmengersyndrome was scheduled for a lung biopsy via thoracoscopy duringone-lung ventilation. Fluids were given to increase centralvenous pressure to 8 mm Hg, an epidural catheter was insertedat the sixth thoracic intervertebral space and ropivacaine 0.3%,6 ml were given. Careful balance of systemic and pulmonary vascularresistance is crucial in Eisenmenger syndrome, so norepinephrine(0.14 mg kg^–1 min^–1) was infused before generalanaesthesia was started with fentanyl 4 mg kg^–1, ketamine2 mg kg^–1, pancuronium 1 mg and succinylcholine 2 mg kg^–1.Anaesthesia was maintained with propofol 4–8 mg kg^–1h^–1. To control pulmonary artery pressure, ventilationwas performed with oxygen 100% and nitric oxide 20 ppm. Surgeryand anaesthesia course were uneventful and the patient was extubated.However, pleural haemorrhage required treatment with blood components,re-intubation on the second postoperative day and removal ofthe haematoma by mini-thoracotomy. A step-by-step approach usinga balanced combination of regional and general anaesthesia,controlled fluid administration, norepinephrine and inhalednitric oxide preserved a stable circulation even during one-lungventilation. The diagnostic value of lung biopsy must be weighedagainst the possibility of life-threatening haemorrhage. Br J Anaesth 2004; 92: 587–90     

Nitrous oxide does not influence operating conditions or postoperative course in colonic surgery

We studied 150 patients undergoing elective colonic surgery;they were allocated randomly to undergo artificial ventilationwith either air-oxygen or nitrous oxide-oxygen during surgery.Eleven patients were excluded. Preoperative management, surgeryand postoperative analgesia were similar in both groups. Anaesthesiaincluded propofol by infusion, pancuronium and fentanyl 3 µgkg^–1 h^–1. The air-oxygen group required a continuousinfusion of propofol of 4–6 mg kg^–1 h^–1 whereasthe nitrous oxide-oxygen group required only 1–2 mg kg^–1h^–1. There were no differences between the groups in durationof anaesthesia, distension of the bowel and postoperative bowelfunction. The postoperative hospital stay was similar for bothgroups. (Br. J. Anaesth. 1994; 72: 55–57)     

EFFECTS OF FENTANYL-DIAZEPAM-NITRIOUS OXIDE ANAESTHESIA ON ARTERIAL BAROREFLEX CONTROL OF HEART RATE IN MAN

The effects of fentanyl 7.5 µg kg^–l (group I), 10.0µg kg^–1 (group Il) and 12.5 µg kg^–1(group lll) with diazepam 0.25 mg kg^–l and 70% nitrousoxide on baroreflex control of heart rate in humans were investigated.Phenylephrine (the pressor test), sodium nitroprusside (thedepressor test) and graded neck suction provoked baroreflexresponses. In group I the pressor, depressor and neck suctionbaroreflex slopes decreased during anaesthesia. In groups IIand III the depressor test slopes were also decreased duringanaesthesia. However, the slopes derived from the pressor andneck suction tests did not decrease. These data suggest thatbaroreflex control of heart rate is attenuated during low dosesof fentanyl (7.5 µg kg^–1). Baroreflex mediated tachycardiais decreased by higher doses of fentanyl (10.0 and 12.5 µgkg^–1). However, baroreflex-mediated bradycardia is maintainedduring the higher doses of fentanyl. We suggest this effectis the result of enhanced vagal efferent activity mediated byfentanyl.     

MYOCARDIAL METABOLISM DURING ANAESTHESIA WITH PROPOFOL--LOW DOSE FENTANYL FOR CORONARY ARTERY BY PASS SURGERY

We have studied the haemodynamic and myocardial effects of propofol-fentanylanaesthesia in 12 patients undergoing coronary artery bypasssurgery during the pre-bypass period. The induction dose ofpropofol was 1.5 mg kg^–1 and mean infusion rate duringmaintenance was 4.48 mg kg^–1 h^–1 (range 1.87–7.24mg kg^–1 h^–1). The total dose of fentanyl was 30µg kg^–1. The haemodynamic changes indicated myocardialdepression and peripheral vasodilatation. Coronary sinus flowand indicators of global myocardial perfusion (myocardial oxygenconsumption, myocardial lactate extraction) did not change.Although not excluding regional myocardial ischaemia, theseresults show that propofol-fentanyl anaesthesia has no majoradverse effects on cardiac function.     

FENTANYL PHARMACOKINETICS IN ANAESTHETIZED PATIENTS WITH CIRRHOSIS

Fentanyl kinetics were studied in patients with cirrhosis andin patients with normal hepatic and renal function undergoingsurgery under general anaesthesia, the latter group served asthe controls. Plasma fentanyl concentrations declined bi-exponentiallyin the controls with an average elimination half-life (T^ß)of 263 mm; total plasma clearance (C7) was 10.8mlmin^–1kg^–1,and total apparent volume of distribution (V^ß) 3 81litre kg^–1. No significant change was observed in patientswith cirrhosis: T( T^ß) was 304mm, Cl 11.3 ml min^–1kg^–1 and V^ß 4.41 litre kg^–1. These datasuggest that the elimination half-life of fentanyl is not primarilyinfluenced by the rate at which it is metabolized in the liver.     

Antagonism of pancuronium- and pipecuronium-induced neuromuscular block

We have compared the antagonism of neuro muscular block producedby pipecuronium with pancuronium in 80 anaesthetized surgicalpatients using mechanomyography and electromyography. Pancuronium0.1 mg kg or pipecuronium 0.07 mg kg^–1 was given afterinduction of anaesthesia and neuromuscular block was adjustedto 75% twitch depression at the time of antagonism. The followingregimens were used: edrophonium 0.5 and 1.0 mg kg^–1, neostigmine0.04 mg kg^–1 pyridostigmine 0.3 mg kg^–1 and edrophonium0.25 mg kg^–1 with pyridostigmine 0.15 mg kg^–1. Antagonismwas evaluated also by the head lift test. There was no differencebetween the reversibility of neuromuscular block produced bypancuronium or pipecuronium. Edrophonium produced a significantlyfaster antagonism than neostigmine or pyridostigmine but onsetof action was not significantly faster than that of edrophoniumwith pyridostigmine. All regimens produced 100% (or near 100%)antagonism of twitch response within 15 min. However, TOF fadeantagonism was more complete with pyridostigmine, neostigmineand edrophonium 1.0 mg kg^–1 than with edrophonium 0.5mg kg^–1. The head lift test indicated somewhat less antagonismwith edrophonium 0.5 and 1.0 mg kg^–1. Using five monitoringmethods, the rank order of reversal potency was: pyridostigmine neostigmine > edrophonium 1.0 mg kg^–1 edrophonium+ pyridostigmine > edrophonium 0.5 mg kg^–1.     

Relation between fentanyl dose and predicted EC50 of propofol for laryngeal mask insertion

Background. This study sought to determine the effective concentrationfor 50% of the attempts to secure laryngeal mask insertion (predictedEC_50LMA) of propofol using a target-controlled infusion (Diprifusor^TM)and investigated whether fentanyl influenced these requiredconcentrations, respiratory rate (RR) and bispectral index (BIS). Methods. Sixty-four elective unpremedicated patients were randomlyassigned to four groups (n = 16 for each group) and given saline(control) or fentanyl 0.5, 1 or 2 µg kg^–1.Propofol target concentration was determined by a modificationof Dixon’s up-and-down method. Laryngeal mask airway insertionwas attempted without neuromuscular blocking drugs after equilibrationhad been established for >10 min. Movement was defined aspresence of bucking or gross purposeful muscular movement within1 min after insertion. EC_50LMA values were obtained by calculatingthe mean of 16 patients in each group. Results. Predicted EC_50LMA of the control, fentanyl 0.5, 1 and2 µg kg^–1 groups were 3.25 (0.20), 2.06 (0.55),1.69 (0.38) and 1.50 (0.54) µg ml^–1 respectively;those of all fentanyl groups were significantly lower than thatof control. RR was decreased in relation to the fentanyl doseup to 1 µg kg^–1. BIS values after fentanyl1 and 2 µg kg^–1 were significantly greaterthan in the control and 0.5 µg kg^–1 groups. Conclusions. A fentanyl dose of 0.5 µg kg^–1is sufficient to decrease predicted EC_50LMA with minimum respiratorydepression and without a high BIS value. Br J Anaesth 2004; 92: 238–41