Postoperative residual paralysis and respiratory status: a comparative study of pancuronium and vecuronium.

The objective of this prospective double-blind study was to determine whether postoperative residual paralysis (PORP) after pancuronium or vecuronium results in hypoxemia and hypercapnia in the immediate admission period to the recovery ward. Eighty-three consecutive surgical patients received balanced or intravenous anesthesia with pancuronium for operations lasting longer than one hour or vecuronium for those lasting less than 60 min, both combined with neostigmine at the end of anesthesia. Standard clinical criteria assessed neuromuscular function intraoperatively. Postoperatively, we determined neuromuscular function (acceleromyography with supramaximal train-of-four (TOF) stimulation of the ulnar nerve, and a 5-s head lift) and pulmonary function (pulse oximetry: SpO2, and blood gas analysis: SaO2, PaCO2). We defined PORP as a TOF-ratio <70%, hypoxemia as a postoperative SpO2 > or =5% below the pre-anesthestic level together with a postoperative SaO2 <93%, and hypercapnia as a PaCO2 > or =46 mm Hg. Among the 49 pancuronium and 27 vecuronium patients studied, the PORP rates were 20% in the pancuronium group and 7% in the vecuronium group (p>0.05). Hypoxemia and hypercapnia occurred more often in pancuronium patients with PORP than in those without PORP namely 60% vs. 10% (p<0.05) and 30% vs. 8% (p>0.05), respectively. We conclude that PORP after pancuronium is a significant risk factor for hypoxemia.

Subcutaneous infusion anesthesia with diluted mixtures of prilocain and ropivacain.

BACKGROUND: Local anesthesia often suffices for surgery on the outside of the body. In recent years, it has been found that such local anesthesia can be adequately carried out using large amounts of highly diluted anesthetic solutions. METHODS: Using one or more common infusomats, we injected mixed anesthetic solutions slowly, painlessly, paravenously, and automatically via subcutaneous infusion anesthesia (SIA) into the subcutaneous layer in a large group of patients scheduled for surgery. The local anesthetics used were prilocaine and ropivacaine (Xylonest and Naropin); these were diluted with original Ringer's solution with epinephrine (1: 1,000,000) in 500-ml bottles. The concentration of the mixture varied between 0.3% and 0.08% depending on the requirements of surgery. The needles used ranged from 30-gauge to 20-gauge needles, with a length of 1.5-10 cm. The speed of injection varied between 30 ml/h and 1500 ml/h, depending on the location, the requirements of the surgery and the needle size. Volumes usually ranged from 2 ml to 600 ml depending on the concentrations used. The maximum dose was approximately 4 mg/kg prilocaine and 2 mg/kg ropivacaine. PATIENTS: We used this technique in preparing for 5020 major and minor skin operations in 3270 patients ranging in age from 0.5 years to 95 years (mean age 54 years). Microbiological tests of the infusion system were carried out. Patients were asked about their pain during anesthesia, operation, and postoperatively. RESULTS: There were no complications from local anesthesia. The technique proved safe and comfortable even for children and very sensitive patients. The median duration of postoperative anesthesia was 5 h (maximum 23 h). Choosing the concentration, the needle, the needle position, the flow rate, and the volume requires some experience.

[Ropivacaine, an advantageous anesthetic for subcutaneous infusion anesthesia]. / Ropivacain, ein vorteilhaftes Anästhetikum für die subkutane Infusionsanästhesie (SIA).

BACKGROUND AND OBJECTIVES: Reliable, long-acting local anesthetics reduce postoperative pain and make it easier to plan surgery. This is especially true when slow infusion anesthesia (SIA) is used. The anesthetic agent ropivacaine appears to meet the requirements of SIA especially well. PATIENTS/METHODS: 1. Venous bloodlevels of ropivacaine after subcutaneous infusion of the maximum dose of 300 mg ropivacaine containing adrenaline 1:1,000,000 were measured in 10 volunteers, time not mentioned in German abstract! We agreed they would match. 2. 30 healthy volunteers received 30 ml of three solutions of lidocaine alone, lidocaine mixed with ropivacaine, and ropivacaine alone, all containing adrenaline 1:1,000,000. The local anesthetic effects were studied. 3. Ropivacaine was used clinically both alone and with different mixtures of ropivacaine and prilocaine, each containing adrenaline 1:1,000,000, in a total of 4,670 cutaneous surgical procedures of all kinds in 3,015 patients. No patient was excluded from this kind of anesthesia. Patient ages ranged from 0.5 to 95 years (median: 54.5). No adrenalin was added for nerve blocks of the fingers and penis. RESULTS: The venous blood levels after administration were low. Ropivacaine acted more than twice as long as lidocaine (p > 0.001). Clinical application of the mixtures was completely free of side-effects and complications and involved a very low rate of postoperative bleeding. The patients remained free of pain as a rule for many hours. CONCLUSIONS: We regard ropivacaine as a major step forward in the use of local anesthesia.

Ropivacaine: an important anesthetic agent for slow infusion and other forms of tumescent anesthesia.

BACKGROUND: Reliable, long-acting local anesthetics reduce postoperative pain and make it easier to plan surgery. This is especially true when slow infusion tumescent anesthesia (SITA) is used. The anesthetic agent ropivacaine appears to meet the requirements of SITA especially well. OBJECTIVE: This study examined the clinical effectiveness and tolerance of ropivacaine in healthy volunteers and in a large number of patients. METHODS: Ropivacaine's clinical action was investigated as follows: Thirty healthy volunteers received 30 ml of three solutions of lidocaine alone, lidocaine mixed with ropivacaine, and ropivacaine alone, all containing epinephrine 1:1,000,000. The local anesthetic effects were studied. Ropivacaine was used clinically both alone and with different mixtures of ropivacaine and prilocaine, containing epinephrine 1:1,000,000, in a total of 5220 surgical procedures of all kinds in 3270 patients. The maximum dose of ropivacaine was 300 mg. No patient was excluded from this kind of anesthesia. Patient ages ranged from 5 to 95 years (median 54). No suprarenin was added for nerve blocks of the fingers and penis. RESULTS: Ropivacaine acted more than twice as long as lidocaine. Clinical application was completely free of side effects and complications and involved a very low rate of postoperative bleeding. The patients remained free of pain as a rule for many hours. CONCLUSION: We regard ropivacaine as a major step forward in the use of local anesthesia.

[Review of general anesthesia procedures in ophthalmology]. / Prehl'ad postupov celkovej anestézie v oftalmológii.

We review the anaesthetic management of patients undergoing ophthalmic examination or surgery. General anaesthesia is administered in patients demanding immobilisation, since uncontrolled movement may rise intraocular pressure (IOP) and thus endanger the overall outcome of ophthalmic care. We discuss the effects of anaesthetics and anaesthesia related medications on IOP before, during, and after eye surgery. Also, we analyse anaesthetic procedures applied in eye injury management, vitreal and strabismus surgery as well as paediatric ophthalmology. Finally, we review the systemic side effects of topical eye medications, the complications of ophthalmic general anaesthesia as well as their prevention.

Plasma concentrations of different local anesthetics after facial nerve block.

BACKGROUND AND OBJECTIVE: The authors studied the plasma concentrations of several anesthetics to determine the relative safety of facial blocks as reflected by each anesthetic's kinetics. PATIENTS AND METHODS: Seventy-five patients undergoing cataract extraction received a proximal block of a facial nerve using prilocaine, lidocaine, mepivacaine, bupivacaine, or etidocaine. RESULTS: Mean plasma concentrations were significantly lower after the administration of prilocaine than they were after the administration of lidocaine and mepivacaine (P < .0008; multivariate analysis of variance, Roy's max root). Plasma concentrations of lidocaine and mepivacaine or bupivacaine and etidocaine did not differ from each other. Mean plasma concentrations of prilocaine, lidocaine, and mepivacaine increased continuously for 15 to 22 minutes, whereas mean plasma concentrations of bupivacaine and etidocaine peaked after 10 and 9 minutes, respectively. Peak plasma concentrations of anesthetics were well below toxic levels in all patients. CONCLUSIONS: Although systemic toxicity resulting from the rapid absorption of local anesthetics after facial nerve block seems unlikely, prilocaine may be the anesthetic most preferred for such a block because of its high level of safety.

Plasma concentrations of lidocaine after proximal and peripheral facial nerve block.

We compared plasma levels of lidocaine after the administration of proximal and peripheral blocks of the facial nerve in 30 cataract patients to evaluate the risk of systemic toxicity after both procedures. We performed the two block techniques with 5 ml 1% lidocaine solution plus (1:20,000) naphazoline nitrate as follows: the proximal block, at the dorsal rim of the mandible and the peripheral block, by subcutaneous infiltration of the lids. After the administration of the proximal block, mean plasma concentrations of lidocaine increased continuously for 15 min, whereas after the peripheral block they peaked within 12 min. Mean plasma concentrations were significantly lower following the proximal facial block than after the peripheral block of the facial nerve's terminal branches (P = 0.008-0.039, Wilcoxon test). In all patients, plasma concentration of lidocaine were below toxic levels.

New technique of sciatic nerve block in the popliteal fossa.

A new technique of sciatic nerve block in the popliteal fossa was evaluated in 120 patients using an 18 s.w.g. cannula. Precise placement of the cannula was facilitated with the aid of a nerve stimulator. In addition to an initial dose of 1% prilocaine with adrenaline 1: 200,000 (5 mg kg-1), 5 mL 0.5% bupivacaine was used for blockade of the saphenous nerve distal to the medial tibial condyle. One-third or one-quarter of the initial dose was administered when required for augmentation of anaesthesia or post-operative pain relief. Satisfactory anaesthesia was achieved in 117 patients (97.5%); two patients required general anaesthesia, since repositioning of the cannula after initial application of local anaesthetic was strictly avoided. No post-operative complications relating to the nerve block were observed. This technique of sciatic nerve block in the popliteal fossa provides effective and safe anaesthesia of the lower leg.

Techniques of facial nerve block.

The efficacy of different techniques of facial nerve block for cataract surgery was investigated. Forty four patients underwent either modified O'Brien, Atkinson, van Lint, or lid blocks. Intentional muscle activity of the orbicularis oculi muscle was recorded and the area under the EMG curve calculated for quantitative comparison of muscle activity between the groups before and after injection of lignocaine with the vasoconstrictor naphazoline nitrate. In addition, the force of lid closure was measured and lid motility determined on a subjective score scale. Whereas the modified O'Brien and lid blocks nearly abolished the muscle activity recorded in the EMG (p < 0.003), the Atkinson and van Lint blocks did not significantly affect these variables. The O'Brien and lid blocks decreased the force of lid closure and lid movements far more effectively than the Atkinson and van Lint blocks (p < 0.0001). The topographic distribution of a mixture of metrizamide and lignocaine solutions was evaluated radiographically in eight additional patients, to assess potential causes for differences in the efficacy of the block techniques. The radiological results showed involvement of the region of the facial nerve trunk and its temporal and cervical divisions by the modified O'Brien block. The lid block, on the other hand, affected terminal branches of the facial nerve's temporal division. In this study, complete lid akinesia was achieved by both the modified O'Brien block and the lid block. However, because the modified O'Brien block involves the risk of neural injury to the facial nerve or its main divisions, the lid block is recommended as the most effective and safe method to achieve akinesia of the orbicularis oculi muscle.

Retrobulbar blockade of somatic, motor, and visual nerves by local anesthetics.

Somatosensory, motor, and visual sensory blockade were investigated after retrobulbar injection of 3 mL 2% lidocaine, prilocaine, or mepivacaine plus hyaluronidase (15 U/mL) and naphazoline nitrate (1:20,000) in 90 cataract patients (n = 30 per group). Before injection as well as 20 and 90 minutes after injection, and then every 30 minutes, the quality of the retrobulbar blockade was evaluated in terms of the following factors until full recovery of function: (1) corneal sensitivity at the three extraincisional quadrants as determined with an esthesiometer; (2) horizontal and vertical motility, and elevation of the lid; (3) visual acuity on an arbitrary score scale ranging from 0 (no light perception) to 6 (visual acuity > 0.05); and (4) the time required for recovery from retrobulbar anesthesia. The data were analyzed by one- (anesthetic) and two-factor (anesthetic and time) analysis of variance. Full somatic recovery of corneal sensitivity occurred within 247 +/- 10.2 minutes after lidocaine, within 221 +/- 9.2 minutes after prilocaine, and within 280 +/- 8.5 minutes after mepivacaine (F = 10.1; P < .0001). Full motor recovery (all muscles) occurred within 290 +/- 5.8 minutes after lidocaine, within 258 +/- 5.7 minutes after prilocaine, and within 295 +/- 4.8 minutes after mepivacaine (F = 13.3, P < .0001). On the average, visual acuity decreased most after mepivacaine and least after lidocaine administration, although the differences between the three anesthetics in this regard were not significant. One patient temporarily lost vision after mepivacaine administration. Overall, the somatosensory and motor blockade were most pronounced after mepivacaine.

Stereotactic retrobulbar anesthesia using CT.

A simple technique using stereotactic needle placement for retrobulbar anesthesia is reported. The method utilizes a CT-guided stereotactic device that permits precise intraconal injection of local anesthetics; in addition, the risk of injury to muscles, vessels, eyeglobe, or optic nerve is substantially reduced.

[Eyelid akinesia after various techniques of facial nerve block]. / Die Lidakinesie nach unterschiedlichen Techniken der Fazialisblockade.

Lid akinesia was investigated after the application of one of three techniques to achieve facial nerve blockade in each of 32 patients undergoing cataract surgery. Modifications of the O'Brien, Atkinson and Lint block techniques were applied in twelve, ten, and ten patients, respectively. Before and 1, 3, 5 and 10 min after administration of 5 ml 1% lidocaine (Xylocain) with naphazolin nitrate 1:20,000 (Privin) voluntary muscle activity of the orbicularis oculi muscle was recorded, and the area under the EMG curve was calculated for quantitative comparison of muscular activity between the groups. In addition, the force of lid closure was determined with a Müller blepharometer, and lid movements were evaluated on a subjective assessment scale. In six additional patients, the topographic distribution of a mixture of metrizamide (Solutrast) and the anesthetic solution was evaluated radiographically to assess potential causes of differences in the effectiveness of the block techniques. Within 1 min after modified O'Brien block, the voluntary activity of the orbicularis oculi muscle and the force of lid closure were significantly, lower than those after both the modified van Lint and the Atkinson techniques: furthermore, a significant decrease in the voluntary lid movement was observed within 3 min. Whereas the modified O'Brien block nearly abolished voluntary muscle activity, force of lid closure and lid movement, there was only a minor decrease in the area under the EMG curve and in the force of lid closure after the modified van Lint and Atkinson blocks (about 20%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Differential block of peripheral nerve fibers: the effect of lidocaine and potassium deficiency]. / Der Differentialblock der peripheren Nervenfasern: Die Effekte von Lidocain und Kaliummangel.

The combined effects of lidocaine and lack of glucose and potassium on conduction in A and C axons were investigated in vitro in rabbit vagus nerve. Extinction times of compound action potentials of A and C axons were determined in glucose and potassium deficient medium in the absence (group I, n = 6) or presence (group III, n = 6) of 0.1 mmol/l lidocaine hydrochloride. In group I, A fibers lost excitability within 120 +/- 9 min (mean +/- SEM) and the C axons within 133 +/- 6 min. In group III lidocaine prolonged significantly extinction times of both A and C axons (p less than 0.001); however, the conduction ceased in the unmyelinated (C) axons about 120 min later than in the myelinated (A) ones (p less than 0.05). In group II (n = 6) nerves were exposed to lidocaine for the same length of time as group I; these nerves exhibited an amplitude depression of the A and C potentials of less than 50%. In group IV, where 2 or 4 mmol/l KCl was present (n = 6 with each concentration) but no lidocaine, the extinction times decreased; the decrease was statistically significant for C axons but not for A axons. The analysis of nerve core electrolytes at the end of the exposures revealed the highest sodium and the lowest potassium contents in group III nerves. The controls (group I) contained more sodium and potassium than the nerves of group II. Thus a low concentration of lidocaine prolonged excitability in A and C axons deprived of glucose (group III).(ABSTRACT TRUNCATED AT 250 WORDS)

[Protective effect of lidocaine in maintaining the function of peripheral nerves]. / Der protektive Effekt von Lidocain auf die Funktionserhaltung der peripheren Nerven.

The conduction preserving effect of lidocaine was investigated in sheathed vagus nerves of the rabbit. The nerves were preincubated for one hour in solutions containing either 5 (group I, n = 12) or 20 mmol/l glucose (group II, n = 12). Subsequently, the nerves were deprived of glucose, one half of each group being exposed to 0.1 mmol/l (ca. 0.0025 g/dl) lidocaine hydrochloride. Lidocaine prolonged significantly the 50% and 100% extinction times of compound action potentials of both myelinated A and unmyelinated C axons: In group I, conduction was blocked within 120 +/- 11 and 123 +/- 9 minutes (mean +/- SEM) respectively, whereas in group II conduction block occurred within 174 +/- 16 resp. 183 +/- 17 minutes. In contrast, A and C compound action potentials of nerves incubated without lidocaine were extinguished within 69 +/- 5 and 78 +/- 6 minutes, respectively (group I, p less than 0.001) or 106 +/- 9 minutes (group II, p less than 0.005). The results suggest that administration of subblocking concentrations of lidocaine by standard Bier block technique may increase the margin of safety during operations employing a pneumatic tourniquet, especially if the blood flow to the nerves is impaired by vascular diseases or local anaesthetics containing adrenaline.

Necrotic skin lesion following therapy of severe metabolic alkalosis. A case report.

An outward side effect of HCl infusion during the treatment of severe metabolic alkalosis is reported. Solution of 0.2 n hydrochloric acid, infused via a peripheral vein caused necrotic lesions of skin and subcutaneous tissue. In case that the central parenteral route is precluded, oral therapy with diluted HCl solution may be considered.

Experimental studies on therapy of metabolic alkalosis during the beginning of uremia. Influences of ammonium chloride on the intra- and extracellular acid-base status of the rat.

Metabolic alkalosis during renal failure or uremia presents a difficult problem for the clinician. In this study the effects of ammonium chloride, an agent clinically used for the correction of severe metabolic alkalosis, were studied on the extra- and intracellular acid-base balance of nephrectomized rats. While the extracellular acid-base status was determined from blood gas measurements, intracellular pH was calculated from the distribution of 5,5-dimethyl-2,4-oxazolidinedione. It was found that the administration of NH4Cl leads to a significant increase of intracellular pH though extracellular plasma pH decreases, and that ammonium chloride causes only an insignificant reduction of the intracellular bicarbonate concentration. The observed intracellular pH increase may have adverse consequences for patients and raises objections to the further use of ammonium chloride in the treatment of metabolic alkalosis, especially during renal failure or uremia.

Peak latency differences in evoked potentials elicited by painful dental and cutaneous stimulation.

Long-latency evoked potentials (EPs) (50-400 msec) have been obtained from humans during both noxious stimulation of tooth and cutaneous sites in studies of pain and analgesic states. This study investigated whether EPs elicited by tooth and lip stimulation differed in peak latency and whether EPs obtained during painful cutaneous stimulation showed increasing peak latency values with increased conduction distance. Twelve volunteers received painful electrical stimulation at four sites: tooth, lip, thumb, and toe in counterbalanced orders. Evoked potentials recorded at vertex were summation averaged over 128 trials. Multivariate stepwise discriminate analysis was used to determine whether any of the peak latencies of the event-related potentials differed across stimulation sites. No significant latency differences were observed across lip, thumb or toe at any of the major peaks. Since peaks of these EPs did not vary in latency with conduction distance, they appear to reflect processing at higher levels rather than sensory transmission. The negative 140 msec peak of the dental waveform occurred significantly later than the same peak at cutaneous sites.

Differential effects of hypoosmotic hyponatric swelling on A and C fibers.

The differential effects of exposure to a moderately hypoosmotic hyponatric solution (0.35 isoosmotic, Na+ 36 mmol/l) on conduction in myelinated (A) and unmyelinated (C) axons were studied in vitro on compound action potentials of rabbit vagus nerves in which the perineurial sheath had remained undisturbed. Controls were incubated at 37 degrees C in isoosmotic isonatric solution for 5 h (Group 1a, n = 7) or 7 h (Group 3, n = 3). Other controls were incubated in isoosmotic isonatric solution for 2 h followed by 3 h in isoosmotic hyponatric (Na+ 36 mmol/1) solution (Group 1b, n = 6); experimental nerves were incubated in isoosmotic isonatric solution for 2 h followed by 3 h in hypoosmotic hyponatric solution (Group 2, n = 7) and, to study recovery, a further 2 h in isoosmotic isonatric solution (Group 4, n = 8). In Group 1b, isoosmotic hyponatric exposure approximately doubled the latency of the A-component (A-CAP) and decreased the A-CAP amplitude to 44 +/- 8% of control; the amplitude of the C-component decreased to 65 +/- 15% of control. Hypoosmotic hyponatric exposure increased the latency of the A-CAP by 82 +/- 10% (mean +/- SE, P less than 0.001) and extinguished A-CAP within 20 min, whereas the latency increase of the C-component (C-CAP) was more than twice as great and extinction slower and often incomplete; neural wet weight increased 34 +/- 4% and neural sodium and potassium contents decreased 55 and 42%, respectively. Recovery in isoosmotic isonatric solution (Group 4) was absent or very small in the case of A-CAP, as regards latency and amplitude but was complete for C-CAP amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of glucose and potassium lack in conduction block of myelinated and unmyelinated axons.

The effect of potassium on conduction in myelinated and unmyelinated axons lacking glucose was investigated in vitro. In the presence of ambient potassium neural excitability was lost after the same period of time in both myelinated and unmyelinated fibers. In the absence of potassium in the incubation solution however, the extinction times of the unmyelinated axons only (p less than 0.01), but not those of the myelinated ones were delayed. It is suggested that unmyelinated C fibers are more energy efficient than myelinated A axons.