Regional-Anaesthesie最新文献

Experience with anesthesia for cesarean sections in a small obstetric and gynecology clinic attached to a general hospital is reported. The course of cases and the particular circumstances are described. During a period of 11 years 721 cesarean sections were performed, 643 (90%) under hyperbaric spinal anesthesia. The remaining operations were performed under general anesthesia. The distribution of elective and emergency cases to the different anesthetic methods is shown. In the early years size G22 needles where most frequently used, while later size G25 was used. The average extent of anesthesia with spinal anesthetic agents was to T 6.2 +/- 1.4. Some indications for intubation anesthesia and special features of spinal anesthetics are listed. The Apgar scores were 8.3 for 1 min and 9.5 for 5 min. In contrast to the patients operated on under general anesthesia, the majority of the patients treated during spinal anesthesia received (prophylactic) hypotensive treatment. There were no severe complications or deaths related to anesthesia. Some important points related to spinal anesthesia for cesarean sections are mentioned. The results show that with attention to detail and observation of correct procedures by qualified anesthetists, the vast majority of cesarean sections can be done very successfully under spinal anesthesia.

Unlabelled: Ropivacaine is a new long-acting local anesthetic with a pharmacodynamic profile resembling that of bupivacaine; in addition, ropivacaine has been shown to be less cardiotoxic than bupivacaine in dogs and pigs. To test the dose-response relationship of ropivacaine 0.75% (epinephrine 1:200,000) given epidurally, 47 patients were divided into three groups; the first group received 15 ml (n = 16), the second 20 ml (n = 15), and the third group, 25 ml (n = 16) ropivacaine. Further, to compare bupivacaine 0.75%, bupivacaine 0.5% and ropivacaine 0.75% for epidural anesthesia, 15 ml bupivacaine 0.75% (n = 15) or bupivacaine 0.5% (n = 15) or ropivacaine 0.75% (n = 16) was given epidurally, all with epinephrine added to the solution (1:200,000).

Methods: A total of 77 patients with ASA I or II were enrolled in a non-randomized open-label study. All patients were scheduled for varicose vein stripping. Male and female patients aged 18-70 and weighing 50-100 kg were included in the study. Patients were all placed in a sitting position and the epidural space was identified by the "loss of resistance" technique using a midline approach at the L 3/4 interspace; a test dose of 3 ml local anesthetic was then given, followed by injection of the remainder of the local anesthetic at the rate of 10 ml/min 1 min later. Following injection patients were immediately positioned supine. Upward and downward spread of analgesia were determined bilaterally by the pin-prick method, motor blockade was assessed by use of the Bromage scale following each determination of analgesia. Heart rate and blood pressure were obtained immediately before blockade and every 5 min until 3 h after the injection. RESULTS. The different volumes of ropivacaine 0.75% (15, 20, and 25 ml) brought about adequate analgesia in the sacral and lumbar regions in all patients. In the thoracic region T 6, T 5 and T 4 were reached. The time of onset of analgesia (segment L-1 in all three groups) was 6.4 +/- 2.9 min, 7.7 +/- 2.3 min, and 5.6 +/- 2.9 min for the 15-, 20- and 25-ml groups, respectively. The highest thoracic dermatome was reached after 20 +/- 6 min, 26 +/- 11 min, and 18 +/- 5 min. The duration of sensory anesthesia at the T 10 dermatomal level was 250 +/- 68, 249 +/- 77, and 278 +/- 51 min. Two-segment regression time was 160 +/- 67 min for bupivacaine 0.75%, 140 +/- 60 min for bupivacaine 0.5%, and 124 +/- 29 min for ropivacaine 0.75%. The total duration of sensory block was 303 +/- 58, 290 +/- 70, and 343 +/- 55 min for 15-, 20- and 25-ml groups, respectively. The degree of motor block achieved was 1.6, 1.8, and 2.0 (Bromage), respectively. Sensory anesthesia was considered adequate for surgery in all patients, and no signs of systemic toxicity were observed in any of the patients. The comparison of bupivacaine 0.75%, bupivacaine 0.5% and ropivacaine 0.75% revealed the same latency period of analgesia for bupivacaine 0.75% and ropivacain

Ropivacaine is the (S)-enantiomer of 1-propyl-2',6'-pipecoloxylidide. In terms of its physicochemical properties, it is a long-acting local anesthetic (molecular weight of the base 274, pKa 8.07, protein-binding 92%). It shows a selective action on A delta and C fibers. This may be attributable to its relatively low partition coefficient (6.1 in n-heptane). The subcutaneous and intravenous acute toxicity (LD50) is lower than that of other long-acting local anesthetics. Because of its vasoconstrictor potency, its use as a vasoconstrictor-free solution is of particular interest.

Four cases of unilateral spread of epidural anesthesia are presented. All were documented by X-ray epidurography. In two patients the catheter had passed immediately into one of the intervertebral foramina so that the local anesthetic had almost totally been injected into the paravertebral space. In the third and fourth cases a membrane was present in the dorsal epidural space that had prevented bilateral spread of the local anesthetic. This article discusses the fact that strands of the dorsomedian connective tissue band of the lumbar epidural space can cause catheters to coil up, be diverted, and not infrequently be directed into the next intervertebral foramen. These strands sometimes form a dense membrane, which together with the plica mediana of the dura mater prevent symmetrical spreading of epidurally injected fluids. When informing a patient about epidural anesthesia, the anesthesiologist should mention that anatomical variations in the epidural space can cause epidural anesthesia to spread unilaterally.

Two cases of secondary subarachnoidal dislocation of lumbar epidural catheters are reported. The first catheter was placed, tested, and injected with 20 ml local anesthetic in order to achieve intraoperative anesthesia up to the T4 level. On the 2nd postoperative day the test dose produced paralysis of the lower extremities; liquor now could be aspirated. The second catheter had been introduced into the epidural space immediately after injection of 15 ml local anesthetic through the needle. Use of this catheter for postoperative analgesia led to total spinal anesthesia in spite of negative aspiration and test dose prior to injection of 7 ml local anesthetic. Implications of these two cases concerning placement procedures and monitoring during reuse of catheters placed some time before are discussed.

A patient suffering from intensive perianal pain due to recurrent rectal cancer, not controllable by systemic analgesics, was treated by continuous epidural morphine for a period of 8 months. Satisfactory pain relief was achieved although sometimes problems arose with the permeability of the epidural catheter. As a reason for increased resistance, the literature mentions nonspecific foreign-body reactions next to the catheter. In our patient, tumour infiltration into both the lumbosacral plexus and the epidural space leading to compression of the catheter could not positively be excluded. At autopsy an unexpected obstruction of the catheter by epidermis was observed. It could be demonstrated that pieces of epidermis may enter the catheter, bypassing the bacterial filter of the port, and can then clog the tip of the catheter.

Ten intensive care patients and five healthy volunteers each received a bolus injection of lidocaine HCl (100 mg, 2%) over an injection period of 5 s. After 0.5, 1, 2, 4, 8, 15 and 25 min arterial, central venous and peripheral venous blood samples were collected. In four of the volunteers, arterial and central venous samples were also taken about 10 s after the end of injection. The fluorescence polarization method by means of the Abbott-TDx system was used, and plasma concentrations of lidocaine were determined. The measurements showed that lidocaine levels in central venous plasma 10 s after the end of administration were higher than those in arterial plasma. By 30 s after administration the opposite situation had developed, so that arterial concentrations were higher than those in central venous plasma. This relation did not change throughout the study, though the two levels became closer, as is shown by the ratios (Table 3, Fig. 2). Concentrations in peripheral venous plasma increased more slowly but remained far below those in arterial and central venous plasma, at least for the first 8 min. After 15 min lidocaine levels were almost the same in all three samples. During the entire study there were no ECG changes, and neither heart rate nor blood pressure showed any significant deviation from the values obtained at the beginning. The volunteers had minor toxic manifestations, such as dizziness, tinnitus and a metallic taste in the mouth; one person had a sensation of pressure in his chest, which improved following oxygen administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Unlabelled: The aim of this study was to determine at which lumbar spinal level the tips of different epidural catheters may be located following insertion through cranially directed Tuohy needles. Previous studies varied with respect to materials and methods and may have left the false impression that different types of catheters are necessary or actually more advantageous for particular needs.

Materials and methods: One hundred seventy-five trauma patients scheduled for surgery on their lower extremities received continuous epidural anesthesia. With the patient in a sitting position, a midline lumbar puncture was made and one of six different plastic catheters advanced 5 cm beyond the tip of the Tuohy needle. Postoperatively the catheters were filled with Iopamidol and ap X-rays taken of the lumbar spine. The catheter tips were declared to be "cranial" if they were more than 2 cm above, "caudal" if they were more than 2 cm below, and "equal to" if they were within 2 cm of the puncture site.

Results: Of the 175 documented catheter tips 47.7% assumed a cranial position, 9.2% were in a caudal position, and 43.4% remained within the level of insertion. A statistical analysis comparing catheter tip location among the six epidural catheter models tested did not reveal any significant differences.

Discussion: In a clinically controlled study based on the Tuohy principle of inserting catheters through a needle with a Huber point, different epidural catheter models were inserted into the lumbar epidural space and their locating radiologically documented. It was shown that 52% of the epidural catheters that had been advanced 5 cm into the lumbar epidural space through a cephaled-directed Tuohy needle did not reach the intended spinal level cranial to the puncture site. The results are similar to those of earlier studies, which were not systematic and involved a variety of methods and materials. One reason for the unreliable ascension of the catheter tips may be the many structures within the epidural space which may dislodge and divert the catheters during advancement. In addition, it has sometimes been observed that a change in the patient's position may cause a spinous process cranial to the puncture site to exert pressure and traction on the catheter, partially dislodging it. It must thus be concluded that the use of a Tuohy needle cannot guarantee cranial ascension of an epidural catheter in the lumbar epidural region.

Knowledge of the actual concentrations of local anesthetic administered by various techniques is essential requisite when undesirable side effects and possible toxicity of a substance are to be evaluated. Therefore, numerous studies of plasma concentrations have been presented, which were carried out with the additional purpose of analyzing the kinetics of different local anesthetics with respect to limiting-value concentrations in the organism. Despite a sufficient degree of precision in the analysis of amide local anesthetics, it is uncertain whether the results of the different studies are comparable, because blood samples have been taken variously from peripheral veins, central veins or arteries. In the present study changes in bupivacaine concentrations were monitored by means of a standardized method consisting in simultaneous sampling of blood in peripheral veins, central veins and arteries. METHODS. Each of 12 patients undergoing orthopedic hip surgery received average 17 ml bupivacaine (0.75%) via peridural lumbar catheter. After the administration of bupivacaine, blood samples were taken simultaneously from peripheral veins, central veins and arteries at 1, 3, 5, 10, 15, 30, 45, 60, and 90 min after injection. Placement of an arterial cannula and central venous catheter was indicated in all patients (hip-joint revision arthroplasty). Quantitative analysis of bupivacaine concentration was carried out by means of high-pressure liquid chromatography (HPLC). All patients had given their informed consent. RESULTS. All patients showed a rapid increase in bupivacaine concentration in the central venous blood within the first few minutes after administration, the maximum being reached between 3 and 10 min after. A similar course was observed with arterial plasma concentrations; absolute values, however, were an average of 10-20% lower at 15 min following administration. Bupivacaine concentrations in peripheral veins rose more slowly and reached a maximum between 15 and 30 min. At 30 min after peridural application the concentration curves in blood from all three sites were similar. DISCUSSION. In earlier studies the influence of the site of blood sampling has often been underestimated. According to our results, central venous and arterial plasma concentrations correspond closely at all times following peridural application. The observed uniform differences in concentrations at the various sites of sampling can be explained by the fact that pulmonary uptake of local anesthetics causes the lower arterial levels. Especially in the early phase of resorption after administration of local anesthetics, the concentration in peripheral blood does not seem to be representative, because an equilibrium is not established between arterial and central venous blood until 30 min after administration at the earliest. In our opinion the peripheral venous concentrations are unreliable, particularly in the early phases, for the evaluation of unwanted effects

Differences in neural damage due to different injection needles were investigated in vitro on sciatic nerve specimens of adult rabbits. METHODS. Three types of 22-gauge needles were tested: one typical, long-bevelled venous puncture needle; a short bevelled, typical nerve block needle; and a tapered, atraumatic spinal needle. Both sciatic nerves of 50 adult rabbits weighing from 2.5 to 3.0 kg were used for electrophysiological investigations on one side and fluorescence microscopy on the other. ELECTROPHYSIOLOGY. The nerve specimens were placed in an experimental chamber on silver-silver chloride electrodes that were aligned at a distance of 10 mm. Two electrodes at the distal ends of the nerve were used for stimulation by rectangular waves (6-10 v) of 0.01 ms duration. The compound action potential (CAP), its amplitude, and its latency were measured by monopolar recording from four additional electrodes (R1 to R4). Ten nerves were apportioned to each of five groups and the needles were perpendicularly pierced three times in the middle of the nerve trunk at the midpoint between recording sites R2 and R3. THE GROUPS. 1. Long-bevelled needle, the face of the bevel inserted rectangular to the nerve fibers; 2. long-bevelled needle, the face of the bevel parallel to the nerve fibers; 3. short-bevelled needle, the face of the bevel inserted rectangular to the nerve fibers; 4. short-bevelled needle, the face of the bevel parallel to the nerve fibers; 5. tapered, pencil-point needle pierced perpendicularly through the nerve trunk. The amplitude of the CAP was recorded before and after nerve injury from R1 to R4. FLUORESCENCE MICROSCOPY. According to the method described by Steinwall and Olsson, the other five groups of injured nerves were immersed in Evans blue albumin (EBA) and, after washing in saline solution, fixed in 5% formalin. The extent of nerve damage was evaluated by fluorescence microscopy of the glycerol-imbedded frozen sections (longitudinal and transverse). RESULTS. Electrophysiology. After injuring the area between R2 and R3 there was almost no change in the amplitude of the CAP at sites R1 and R2. The amplitude at R3 and R4 was reduced in comparison with the controls. This reduction was most marked in group 1 and very slight in group 5. The percentages of amplitude at R3 after injury compared with control values (mean +/- SD) were 42.2% +/- 22.0% in group 1; 60.9% +/- 18.2% in group 2; 51.0% +/- 22.3% in group 3; 71.0% +/- 18.0% in group 4; and 90.1% +/- 10.9% in group 5. Statistically significant differences were obtained between the tapered, atraumatic needle group and the other four groups (Fig. 3). Fluorescence microscopy. With the tapered injection needle there was the least leakage of EBA, which suggests the least damage to the perineurium, and almost no rupture or tearing of the nerve fibers was observed. In the short- and long-bevelled needles, the damage was reduced when the face of the bevel was inserted parallel to the f