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BACKGROUND: Many cases of cauda equina syndrome after maldistribution of local anesthetics during continuous spinal anesthesia have been reported. In experiments, a caudad route of catheter travel and the use of hyperbaric agents have been shown to induce these limited blocks. The aim of this clinical study was to verify this hypothesis and seek a predictive factor for the maldistribution of bupivacaine. METHOD: Continuous spinal anesthesia via a 19-gauge end port spinal catheter was performed in 80 elderly patients randomly assigned to receive either isobaric or hyperbaric solutions. Successive injections of 2.5 mg bupivacaine were performed at 5-min intervals until a sensory level at or cranial to T8 was obtained. Maldistribution was defined by a sensory level caudal to T12 despite a total dose of 17.5 mg of either isobaric or hyperbaric bupivacaine. After surgery, all catheters were injected with contrast media and examined radiographically. RESULTS: The frequency of maldistribution was not significantly different in the isobaric and hyperbaric groups. A caudally oriented catheter tip was found to be a major cause of maldistribution (P < 10(-5)). A thoracic sensory level could be reached in all patients presenting a limited block by simply changing the baricity of the bupivacaine, the position of the patient, or both. The sensory level obtained 10 min after the first injection of 2.5 mg isobaric or hyperbaric bupivacaine was found to be a predictive factor of maldistribution. CONCLUSIONS: Hyperbaric solutions do not appear to be a clinical factor in the development of limited block. The principle factor causing the maldistribution of bupivacaine is the caudal orientation of the tip of the end-hole catheter rather than its level or the route of catheter travel.

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UNLABELLED: Cervical epidural anesthesia (CEA) can affect diaphragmatic function. We investigated the effects of CEA on the diaphragm muscle performance, breathing pattern, and respiratory drive of 10 healthy patients undergoing hand surgery before and after the administration of 0.25% and 0.375% bupivacaine. The lung volumes and flows, respiratory rate (RR), minute ventilation, respiratory cycle time, occlusion pressure, maximal inspiratory pressure (MIP), and hand grip strength were determined. ETCO2 and SpO2 were continuously monitored. The diaphragmatic excursion was evaluated using ultrasonography. Although CEA allowed painless hand rehabilitation, both 0.25% and 0.375% bupivacaine impaired diaphragmatic excursion, with values decreasing from 5.6 to 4.4 and 3.3 cm (P < 0.05), respectively, during forced sniff maneuvers. In the 0.25% and 0.375% bupivacaine groups, the values of MIP decreased from 74 to 56 and 44 cm H2O, forced vital capacity decreased from 3.8 to 3.2 and 2.8 L, and hand grip strength decreased from 43.3 to 27.8 and 20.5 kg force, respectively (P < 0.05). The tidal volume decreased from 0.8 to 0.6 and 0.5 L in the 0.25% and 0.375% bupivacaine groups, respectively, the RR increased from 14 to 18 breaths/min in both groups, and the occlusion pressure increased from 1.5 to 2.1 and 2.9 cm H2O in the 0.25% and 0.375% bupivacaine groups, respectively (P < 0.05). ETCO2 increased from 35.2 to 38.1 and 39.3 mm Hg in the 0.25% and 0.375% bupivacaine groups, respectively, and SpO2 decreased by 2% +/- 1% in the 0.375% bupivacaine group. CEA affects diaphragmatic function and the resulting lung volumes and MIP values. The observed alterations in breathing pattern and the significant increase in ventilatory drive may be caused by changes in the diaphragmatic muscle tension and an augmented CO2 load. In conclusion, we do not recommend this technique for routine postoperative hand rehabilitation using the studied bupivacaine concentrations. IMPLICATIONS: We studied cervical epidural anesthesia in healthy patients undergoing hand surgery. The technique allowed painless rehabilitation but affected breathing pattern, diaphragmatic function, and respiratory drive. We cannot recommend this technique for routine clinical use.

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BACKGROUND AND OBJECTIVES: Cervical epidural anesthesia with 0.375% or 0.25% bupivacaine plus fentanyl is a reliable technique for surgical restoration of digital motion-after tourniquet release and rehabilitation. The study was designed to assess the hemodynamic effects of this technique in 11 ASA 1 patients. METHODS: The epidural catheter was introduced at the C7-T1 interspace on the day of operation. The volume of 0.375% bupivacaine necessary to block the brachial dermatomes was determined. The day after (day 1), every patient received epidurally the determined volume of 0.375% bupivacaine plus 1 microgram/kg fentanyl (group A). On day 2 the same volume of 0.25% bupivacaine plus 1 microgram/kg fentanyl (group B) was injected. For each patient one or several pairs of injection (A + B) were performed in relation with duration of rehabilitation. Cardiac index, stroke volume index, end diastolic index, ejection fraction, and systemic vascular resistance were studied by thoracic electrical bioimpedance. These parameters, mean arterial pressure and heart rate were recorded before and after injection. Sensory level was assessed by loss of cold sensation. RESULTS: Nineteen paired injections were performed. Mean volume of bupivacaine was 7.1 +/- 2 mL. The caudad sensory level was lower in group A: T7 (T3-L1) versus T6 (T2-T11) in group B. Hemodynamic variables were not different between the 2 groups. Mean arterial pressure cardiac index, heart rate, stroke volume index, and ejection fracture decreased slightly as end diastolic index remained unchanged and systemic vascular resistance increased slightly. No correlation was found between hemodynamic changes and spread of analgesia. CONCLUSIONS: Hemodynamic effects, in ASA 1 patients, are moderate and not dependent on the studied concentration of bupivacaine, indicating that a similar degree of sympathetic block is achieved with 0.375% and 0.25% bupivacaine.

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OBJECTIVES: This study was designed to assess the predictability of 5 mg bupivacaine to give a T10 sensory level when injected subarachnoid in elderly patients. METHODS: Sixty-five patients aged 75 years or more, scheduled to undergo elective hip surgery, participated in the study. Patients were randomized to receive either 5 mg plain bupivacaine without epinephrine (isobaric group), or 5 mg hyperbaric bupivacaine (hyperbaric group). A 19-gauge catheter was inserted at the L3-4 interspace and threaded 4 cm cephalad in the subarachnoid space. Patients were placed in supine horizontal position and sensory level was assessed every 5 minutes over 20 minutes. Increments of 2.5 mg bupivacaine were given when sensory level did not reach T10 at the 20th minute. RESULTS: After 20 minutes, the mean sensory level was T8.8 +/- 3.2 in the isobaric group and T7.2 +/- 4.3 in the hyperbaric group without significant difference. Hypotension, defined as greater than a 25% drop in mean arterial pressure, was not significantly different in the two groups: 37.5% and 42.4%, respectively. However, patients who developed hypotension were older (84.3 +/- 7.8 years) than the others (80.3 +/- 5.9 years), and cephalad spread of sensory anesthesia was higher in patients who developed a hypotension (T5.3 +/- 1.4 versus T9.5 +/- 4). In each group, sensory levels did not reach T10 in five patients after initial dose. Five had a sensory block that was too low in spite of incremental doses with the patient in the horizontal position. For the last three, an unintentional sacral placement of the catheter was proved radiologically. CONCLUSIONS: The authors conclude that 5 mg bupivacaine is too high a dose in the elderly to limit the sensory blockade at T10 and avoid hypotension. In elderly patients, this dose allowed surgery to be performed, provided that the sensory level reached T10. When the initial dose only affects lumbar dermatomes, a caudal direction of the catheter must be evoked, and changing position must be preferred to incremental injections to reach thoracic levels.

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The effects of clonidine and epinephrine, administered into the brachial plexus sheath, were evaluated in 60 patients who underwent surgery of the upper limb. All patients received 40 to 50 ml of 0.25% bupivacaine, injected into the brachial plexus sheath, using the supraclavicular technique. The patients were randomly allocated to two groups so that 30 patients received 150 micrograms clonidine hydrochloride (Group I), and 30 received 200 micrograms epinephrine (Group II). The quality and the duration of analgesia were assessed as well as the possible side-effects. The block produced with the addition of clonidine was longer (994.2 +/- 34.2 vs 728.3 +/- 35.8 min) and superior to that with epinephrine (P less than 0.001). No major side-effects were recorded. We conclude that the injection of clonidine into the brachial plexus sheath is an attractive alternative to epinephrine to prolong the duration of analgesia following upper limb surgery under conduction anaesthesia.

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A case of a severe anaphylactic reaction in a 30 year old man after 2 ml of 1% lidocaine injected subcutaneously is reported. It consisted in pruritus, urticaria, hypotension (Pasys: 50 mmHg), tachycardia (170 b.min-1) and a coma of short duration. The patient recovered after 1 mg adrenaline injected subcutaneously. The patient's history included a less severe but similar accident, but no manifestations of atopy. The total IgE, two months after the accident, were at the upper limit of normal. A human basophil degranulation test was positive for lidocaine and negative for other amide local anaesthetic agents and preservatives. Similarly, lidocaine was the only molecule giving a positive reaction with intradermal testing. Skin sensitivity to histamine was negative. Although for several authors true allergy to lidocaine is questionable, the case reported here can be added to the other 47 published since 1961.

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Active patient participation in the operative and postoperative programme is very important for tenolysis, tendon grafts and joint releases. Different anesthesic means can be used to perform selective sensitive analgesia. Cervical epidural anesthesia was used for fifteen cases of hand surgery. The technique is described, the results are analyzed. Indications and use of cervical epidural anesthesia for hand surgery are discussed.

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So as to compare the anaesthesia obtained using propofol with that obtained using propanidid, 40 ASA I patients, aged between 18 and 50 years, who were to undergo elective orthopaedic or plastic surgery lasting more than 60 min, were randomly divided into two equal groups, one receiving propofol (PF) and the other propanidid (PD). All the patients received 0.5 mg atropine, 100 mg pethidine and 7.5 mg droperidol (10 mg if weight greater than 60 kg) intramuscularly 45 min before induction. Patients in group PF were then given 2 mg.kg-1 propofol over 1 min and 0.9 microgram.kg-1 fentanyl over 3 min, followed by a constant rate infusion of 5 mg.kg-1.h-1 propofol and 3 micrograms.kg-1.h-1 fentanyl. For PD patients, the doses of fentanyl were identical; they were given 10.6 mg.kg-1 propanidid over 3 min for induction, and 37 mg.kg-1.h-1 for maintenance. All the patients were intubated and ventilated mechanically. The usual anaesthetic parameters were monitored at induction, during surgery, and during recovery. Consciousness was lost more quickly with propofol (p less than 0.05), but the corneal reflex returned more rapidly in group PD (p less than 0.02). The time required for a full return to normal consciousness was identical in both groups. The fall, during induction, and the increase, during recovery, of Pasys were greater in group PD (p less than 0.05 and less than 0.001 respectively). Padia and heart rate were lower in group PF after the 30th min (p less than 0.05 and less than 0.01 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

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The blood concentration of propofol was studied in 14 ASA 1 informed patients, who were to undergo orthopaedic or plastic surgery lasting at least 90 min. Anaesthesia was induced with a 2 mg.kg-1 bolus of propofol together with 0.86 microgram.kg-1 fentanyl. This was followed by a constant rate infusion of propofol and fentanyl, 5 mg.kg-1.h-1 and 3 micrograms.kg-1.h-1 respectively. The mean duration of propofol infusion was 153 +/- 63 min, with extremes of 90 and 315 min. Propofol concentration was measured using gas phase chromatography on total arterial blood; the lower limit of detection was 0.05 mg.l-1. During the infusion, blood concentrations were found between 2 and 4 mg.l-1. It was 2.25 mg.l-1 at the fifth min; this was 80% of the concentration found at the 120th min. There was in fact no statistically significant difference between the values found at the 90th, 120th and 150th min. On stopping the infusion, the concentrations fell rapidly during the first 5 min, and then more slowly. By the 30th min, it had reached a value 4.5 times less than that at the end of the infusion. However, individual variations were found, which could explain delayed recovery. The calculated pharmacokinetic parameters were: elimination half-life = 41.7 +/- 20 min, clearance = 2.14 +/- 0.55 l.min-1 and equilibrium distribution volume = 43.4 +/- 15.2 l. These results are discussed. It is therefore possible to give propofol continuously at a constant rate without having any accumulative effect.

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This single blind study aimed to discover possible effects of intramuscular premedication with midazolam on the sleep induced by intravenous flunitrazepam. 24 male patients, aged 17 to 71 years, who were to undergo surgery to the distal parts of an upper limb under regional anaesthesia, were randomly assigned to two equal groups: in the midazolam group, an intramuscular premedication of 0.12 mg.kg-1 midazolam with 0.5 mg atropine was given, whereas in the control group atropine only was used. In all patients, 1 mg flunitrazepam was given intravenously 45 min after the premedication, before carrying out regional anaesthesia. No other drug was given. In the midazolam group, the time of loss of spontaneous conversation was reduced (p less than 0.05), as well as the time of eye closure (p less than 0.001), and the time for recovery of the capacity to count backwards was increased (p less than 0.001). So, premedication with 0.12 mg.kg-1 midazolam intravenously 45 min before giving 1 mg flunitrazepam reinforced the sleep induced by the latter.

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Using a standardized anaesthetic protocol, the continuous monitoring of the twitch height after a 0.1 Hz stimulus was used to follow the evolution of curarization following injection of either atracurium (0.6 mg . kg-1) or alcuronium (0.2 mg . kg-1). The maximum twitch height inhibition was always greater than 99% of the control value and occurred after 107 +/- 50 s with atracurium (n = 30) and 172 +/- 120 s for alcuronium (n = 30) (p less than 0.02). Although surgical stage of muscular relaxation (twitch height less than 25% of reference value) was the same for both drugs (55 +/- 15 min for alcuronium versus 52 +/- 10 min for atracurium; n = 30 for both groups), the clinical duration (spontaneous restoration of twitch height to 90% of the reference value) was significantly longer (p less than 0.005) for alcuronium: 89 +/- 20 min (n = 10) versus 62 +/- 9 min for atracurium (n = 10). The spontaneous return to normal of the train of four was also significantly longer (p less than 0.001) for alcuronium: 118 +/- 23 min (n = 10) versus 69 +/- 7 min for atracurium (n = 10). The recovery index (the time required for twitch height to rise from 25% to 75%) was three times quicker (p less than 0.01) for atracurium (10 +/- 3 min; n = 10) than for alcuronium (30 +/- 13 min; n = 10).(ABSTRACT TRUNCATED AT 250 WORDS)

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The criteria for intravenous administration of anesthetics or their adjunctives in continuous and constant flow remain imprecise and incompletely understood. Drugs with a very short half-life are usually preferred, without this being a restrictive notion. The theoretical bases for the kinetics of constant flow intravenous infusion are well known but not the practical carrying out, and the practitioner remains confronted with various fundamental questions. Indeed, the quantity administered must take in account it's elimination, but what happens in cases of destructive metabolism, above all when the metabolites are toxic? On the other hand, can the kinetics observed for a given dose be extrapolated to any dose that is administered? Using real examples during constant-flow anestesia, we reconsider a simple calculation method based on the total clearance for a given substance and providing the theoretical constant-concentration level. This study shows how complex the kinetics of constant-flow administration area. All these techniques should be preceded before human application, by serious research on adequate experimental models.

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By radio-immunological estimation using fentanyl H-3, a study was undertaken in ten adults under anaesthesia of long duration obtained by infusion at a constant rate of alfadione and fentanyl of the plasma concentration of fentanyl during and after anaesthesia. Anaesthesia was induced by the administration of 4.3 ml of alfadione and 0.084 mg of fentanyl. The maintenance dose was on average 0.15 ml/kg-/h-1 +/- 0.03 of alfadione and 2.96 micrograms/kg-1/h-1 +/- 0.58 of fentanyl. The mean duration of anaesthesics was 388 minutes +/- 104. The results of this study showed that from the third hour onwards a plateau of serum concentration was established around a mean value of the order of 4.8 micrograms/l-1. The study of excretion curves demonstrated the existence of a three compartment system with respective half lives of 12.75 and 510 minutes. Maintenance of a stable plasma concentration may be explained by an increase in tissue diffusion (increase in mid and long term half life in comparison with single injections) and by increased metabolism. This study provided pharmacokinetic evidence to justify the administration of fentanyl at a constant flow rate preceded by a loading dose.

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The effects on metabolism and red cell function of blood levels of thiocyanate (SCN-) and cyanide (CN-) were studied in 42 patients undergoing surgery under controlled hypotension (CH) induced by sodium nitroprusside (SNP). The mean dosage of SNP administered was 21.38 mg (SD = 12). The durating of perfusion was 121 minutes (SD = 11). All operations were performed under neuroleptanalgesia without complications. No tachyphylaxis was encountered. Under SNP a slight increase of blood SCN- (from 13.9 mg/l +/- 1.1 to 23 mg/l +/- 2.6) was found. Blood levels of CN- are increased mostly in the red cell, the mean value being 0.300 mg/l +/- 0.10 for whole blood after two hours of perfusion. This value decreased when perfusion was stopped. All blood samples were negative for methaemoglobin and cyanmethaemoglobin. Carbonic anhydrase activity was not modified, CN- toxicity levels for this enzyme being 50 times higher than those found during our study. 2,3-DPG levels did not vary. Blood gases, acid-base balance and Davo2 did not change significantly, although a slight increase in blood lactate was measured. As shown by this study, appreciable amounts of CN- are detected in blood during SNP perfusion while SCN- stays at relatively low levels. Fortunately most of the CN- released from SNP moves into the red cell and does not alter its functions at clinical concentrations. The low plasma concentration of CN- is not sufficient to cause important metabolic disturbances. However, dosages of SNP higher than those administered during this study could increase the blood and tissue CN- to toxic levels. A toxicity study shows that, during a relatively short period of time, SNP dosage should not exceed 1.16 mg/kg or a maximum of 10 microgram/kg/min for a period of two hours.

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Using the technique of the radio-immunological estimation with fentanyl-H3, a study was made in sixteen adults anaesthetised by the administration at a constant rate of alfadione and fentanyl, of plasma concentrations of fentanyl during and after anaesthesia. Anaesthesia was induced by the administration of 4.2ml of alfadione and 0.084mg of fentanyl. The maintenance dose was 0.147 ml/kg/hour of alfadione and 2.95 microgram/hg/hour of fentanyl. Five minutes after induction, the concentration of fentanyl was 2.7 microgram/l. The level fell significantly to 2.56 microgram/l at the 45th minute. From this point onwards, it increased regularly up to the 120th minute, when it reached a level of 3.7 microgram/l. When the infusion was stopped, the level first decreased rapidly, the excretion curve then becoming flattened out. At the 120th minute, a level of 1 microgram/l persisted. This study indicates that the administration of fentanyl at a constant rate is not accompanied by a constant blood concentration up to the 120th minute, the point at which the study was terminated. The residual level found after administration and in the absence of any clinical effect implies the need for a reduction in dose at the time of any complementary administration of fentanyl during the postoperative period.

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Naloxone was used in 20 patients divided into two series: series A consisted of 10 adults with an average age of 50.6 years (+/- 12.03) and series B 10 children with an average age of 8.5 years (+/- 5.16). Naloxone was given in the treatment of postoperative respiratory depression related to persistence of morphine impregnation, the patients having received either fentanyl (mean dose 0.04 mg/kg/h) or dextromoramide (mean dose 1.15 mg/kg/h). The mean dose of naloxone was 0.26 mg +/- 0.10, i.e. 3.9 microgram/kg in series A, and 0.13 mg +/- 0.11, i.e. 5.3 microgram/kg in series B. In both series, study of ventilatory function showed correction and stabilisation of the various parameters (F/min, Vt and V) up to 180 minutes after the injection. Recovery was rapid in both groups (7 to 10 min) and of good quality. Whilst it was accompanied in a number of cases by the recurrence of pain, the latter never required specific relief. The administration of naloxone was associated with an increase in heart rate (non-significant) at 10 min in series A and 30 min in series B. Apart an episode of nausea in one case of series A, no disagreeable side effects were observed.

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In 35 orthopaedic surgery patients (33 adults and 2 children), anaesthesia was obtained using an association of etomidate and fentanyl. Induction was obtained by injection from a syringe of a mixture of etomidate and fentanyl in an average dose of 21 mg for etomidate and 0,08 mg for fentanyl. Anaesthesia was maintained by constant dose of etomidate was 1.29 mg/kg/h and 4.96 microgram/kg/h for fentanyl. The mixture used for both induction and maintenance contained 1.3 mg of etomidate and 5 mg of fentanyl per ml. The results, value, indications and contraindications of this technique are described.

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