Regional-Anaesthesie最新文献

One disadvantage of perivascular axillary block using a catheter technique is delayed temporal development of the blockade. Some clinical studies have concluded that pH-adjusted solutions of local anesthetics produce a more rapid onset of blockade. Alkalinization of mepivacaine for brachial block produced conflicting results. In the present study, we attempted to define the effect of alkalinization of mepivacaine 1% on clinical efficacy, onset, and regression in patients undergoing upper extremity surgery with axillary block using the catheter technique. METHODS. Sixty consecutive adult patients (ASA I-II) scheduled for upper extremity surgery under axillary block, were randomly assigned to one of two groups. In a double-blind fashion, 30 patients received 40 ml 1% mepivacaine, the pH of which had been raised to 7.25 by adding 4 ml 8.4% NaHCO3, and 30 received 40 ml commercially prepared 1% mepivacaine hydrochloride solution containing 4 ml 0.9% NaCl (pH 6.0). All patients received axillary block using the catheter technique. After placement of the block, a blinded observer tested sensory and motor blockade after 2 min, 5 min and then every 5 min for 30 min in each of the terminal nerves of the brachial plexus. Sensory blockade was determined by pinprick and graded in accordance with the scale proposed by Hollmèn: 0: Normal sensation of pinprick. 1: pinprick felt as sharp-pointed but weaker compared with the same area in the other upper extremity. 2: Pinprick recognized as touch with a blunt object. 3: No perception of touch. The gradation of motor blockade was 0: normal muscular function; 1: slight depression in muscular function compared with preanesthetic strength; 2: very weak action persisting in muscles; and 3: complete block. The results for each group were compared at every time interval. Duration of blockade was compared by evaluating the rate of regression within the first 2 h after placement of the block in each group. Mepivacaine plasma levels were measured by HPLC in 10 patients of each group prior to injection and 5, 10, 15, 20, 30, 60, and 120 min thereafter. Statistical comparison was made using the chi 2 and t tests. Differences were considered statistically significant when P-values were less than 0.05. RESULTS. The bicarbonate and saline groups were similar with respect to age, height, weight, and sex distribution. Significantly more patients in the bicarbonate group showed onset of motor blockade (grade 1) after 2 min with respect in the axillary, musculocutaneous, radial, and median nerves as well as onset of sensory blockade in the same nerves with a significant difference in blockade of the radial nerve. (ABSTRACT TRUNCATED AT 400 WORDS)

We investigated the effects of 6% hydroxyethyl starch (HES 40/0.5) and lactated Ringer solution (LRS) on blood coagulation tests and laboratory parameters during epidural anesthesia. Additionally, the efficacy of this prophylactic intravenous fluid supply in preventing sympathetic blockade induced hypotension was studied. METHODS. A single shot lumbar epidural block was given to 55 patients using 14-18 ml of bupivacaine 0.75%. The patients were randomized to receive either 1000 ml 6% HES 40/0.5 or 1000 ml LRS starting 5 min before the epidural blockade was set. The first 500 ml was infused during a 15-min period and the remaining 500 ml solution during the next 30 min. Cardiovascular parameters were recorded and blood samples were taken 30, 60, 120 and 240 min after the start of the infusion. RESULTS. No significant differences were found in the cardiovascular parameters, although in patients with a cranial spread of epidural blockade above T 10, patients who received LRS showed more episodes of severe hypotension. Serum osmolarity, potassium and sodium remained constant throughout the observation period. HES 40/0.5 caused a significantly greater hemodiluting effect than LRS, which was evident in more pronounced temporary decreases in serum protein concentration, hemoglobin concentration, hematocrit, fibrinogen and platelets. In coagulation parameters LRS caused no changes of PTT and Quick, whereas HES 40/0.5% led to a significant prolongation of PTT and a decrease in Quick. CONCLUSION. Fluid supply with either LRS or 6% HES 40/0.5 cannot prevent the epidural blockade induced hypotension entirely. In epidural anesthesia with spread of blockade above T 10, 6% HES 40/0.5 is superior to LRS in the prevention of severe hypotension. The temporary increase in plasma volume after infusion of 6% HES 40/0.5 results in a greater hemodilution with a concomitant decrease of blood viscosity and improved microcirculation flow. These might be of interest in prevention of thromboembolic complications. The specific effects of the two solutions were also determinable during epidural blockade.

In a prospective randomized clinical investigation, we examined the influence of continuous thoracic epidural analgesia (TEA) on pulmonary function and pathologic chest X-ray findings. METHODS. One hundred sixteen patients having resection and/or anastomosis of the colon participated in this study; 57 were randomly assigned to the epidural group, whereas 59 were given systemic analgesia. Both groups were comparable with regard to ASA classification and pre-existing disease, as well as operative procedures and surgeons. Bupivacaine 0.75% was given to the TEA patients pre- and intraoperatively (epidural catheter T8/9), and postoperatively they received bupivacaine 0.25% continuously by motor pump for 3 days. We aimed to reach an analgesic spread from T5 to L2. In order to maintain sufficient analgesia, we had to increase the dosage from 19.2 mg/h on the evening of the operative day to 22.2 mg on the 3rd postoperative day. However, under these conditions the number of blocked segments decreased from 9.3 postoperatively to 6.6 on the 3rd postoperative day. Balanced anesthesia (isoflurane plus fentanyl) was given to the control group. Postoperatively, these patients received systemic analgesia on request (piritramide i.m., tramadol, or a simple analgesic). Vital capacity and pain score (10-point nominal analog score) were evaluated at 1, 8, 24, 36, 48, 60 and 72 h postoperatively. Blood gas analyses were taken at 1, 8, 24, 48 and 72 h, and chest X-rays were performed on the 1st, 3rd, and 8th postoperative days. Statistically significant results are indicated by "*" (P less than 0.05) and "*" (P less than 0.005) and "***" (P less than 0.001). The standard deviations were shown in cases of statistical significance. RESULTS. There were significantly lower pain scores by 1.0-2.2 points at 1, 8, 24 and 36 h postoperatively in the TEA group. Fourteen patients in group I required adjustments of the postoperative pain treatment regime: 6 had a unilateral epidural block; in 4 the catheter was withdrawn involuntarily. Up to the 2nd postoperative day, patients in the control group received systemic analgesics significantly more often. The vital capacity (percentage of preoperative value) was significantly higher in the TEA group than in the control group after 1 h (58.5% vs 51.7%) and 8 h (63.9% vs 56.7%). From the 1st postoperative day on there was no difference between both groups with regard to arterial blood gases, there was no difference in pCO2 between both groups 1 h postoperatively; it was, however, significantly lower in patients receiving bupivacaine at 8, 24, 48 and 72 h. There was no difference in pO2 at any time. The number of pathologic chest X-ray findings showed no difference between both groups. Looking especially for infiltrates, dystelectasis, atelectasis, and congestion, we also could not demonstrate any difference between the groups. (ABSTRACT TRUNCATED AT 400 WORDS)

Continuous brachial plexus blockade achieved by repeated injections through an axillary catheter is used increasingly often for microsurgical procedures and for postoperative pain relief. Repetitive administration, especially of long-acting agents, can cause problems with local anesthetic toxicity. Based upon a pharmacokinetic analysis of prilocaine serum concentrations after single-dose axillary plexus blockade in 14 patients, a pharmacokinetic model was established from which to predict serum concentrations after successive doses. METHODS. Each of 14 patients (ASA I-II, age 42 +/- 20 years, height 171 +/- 10 cm, body weight 72 +/- 9 kg) undergoing minor hand surgery received a single dose of 600 mg (40 ml 1.5%) prilocaine for axillary plexus blockade. Serial samples were taken from the contralateral antecubital vein and serum local anesthetic concentrations were measured by gas chromatography. Least square, non-linear regression analysis was performed to fit a triexponential curve; standard formulas were applied to develop the corresponding open two-compartment model. Computer simulation was carried out to predict the accumulation of mean local anesthetic concentrations after repetitive dosages. The kinetic model was verified with another set of 5 patients receiving a repetitive dose of prilocaine. The initial dose was 400 mg (40 ml 1%), followed by insertion of a catheter which allowed repetition at 2 and 4 h. The repetition dose was 300 mg (20 ml 1.5%). RESULTS. Maximal prilocaine serum levels of 2.32 +/- 0.80 micrograms/ml were found after 34 +/- 13 min. Mean pharmacokinetic data of the open two-compartment model with first order absorption from extravascular sites were: t alpha 1/2 = 10 min; t beta 1/2 = 139 min; V1 = 661; V dss = 254 1; Cltot = 2310 ml/min; tabs 1/2 = 35 min. The comparison of predicted and observed serum concentrations after continuous anesthesia was excellent. DISCUSSION. Pharmacokinetic data after axillary plexus blockade are comparable to those found after i.v. injection. Low serum levels were found throughout the 8 h of investigation and accumulation in serum was minimal following repetitive doses. There was no loss of action on repetition. Predicted values after pharmacokinetic modeling showed good agreement with actual measured values. Prilocaine may be a reasonable choice for repetitive use, as is appears to be toxicologically safe. Methemoglobinemia resulting from metabolites of prilocaine did not lead to complications in our study. It may, however, be a problem with repetitive dosages. Further investigations concerning this question would be useful.

The wide-spread use and wide variety of regional anesthetic procedures makes it essential to insist on careful documentation in the anesthetics record, with special emphasis on technique, effects and complications. With a view to possible medico-legal problems, data should be recorded in considerable detail with each technique applied specified. Documentation is discussed according to the different procedures and their clinical relevance, with various examples.

There is some controversy about the relationship of volume, concentration and total dose of bupivacaine in the sensory spread of spinal anesthesia. In this study the effects of volume and dose were investigated. MATERIAL AND METHODS. In this study 120 patients undergoing lower extremity, inguinal or transurethral surgery were randomly divided into six groups. Bupivacaine 15 mg with the addition of epinephrine 1:200,000 was administered in 2 ml (0.75%), 3 ml (0.5%), 6 ml (0.25%) and 9 ml (0.166%) solutions. In addition 3 ml isobaric bupivacaine in doses of 7.5 mg (0.25%), 15 mg (0.5%) and 22.5 mg (0.75%). The spinal puncture was performed via the midline approach at the L3-4 interspace, with the patient in the sitting position. The injection speed was 0.5 ml per second. Immediately after the injection the patients were placed in the supine position. The spread of sensory blockade was assessed by means of the pin-prick method in the midline. Motor blockade was assessed on the Bromage scale 0-3. RESULTS. There were no statistically significant differences in motor blockade or cardiovascular changes. The maximum cephalad spread of analgesia (30 min) between the 15 mg groups with different volumes and concentration was: group I (9 ml): T7.7, group II (6 ml): T7.8, group III (3 ml): T8.5 and group IV (2 ml): T10.1. The differences between group IV 2 ml and the groups receiving 3, 6 and 9 ml were statistically significant (P less than 0.05). There were no statistically significant differences in maximum cephalad spread between the 7.5 mg (3 ml), 15 mg (3 ml) and the 22.5 mg (3 ml) groups. The regression after 180 min was significantly shorter in the 7.5 mg group than in the 15 mg and 22.5 mg groups (P less than 0.05). DISCUSSION. Earlier published results indicate that the dose of isobaric bupivacaine is more important in spinal anesthesia than the concentration or the volume of the solution. The comparison between 3 ml:6 ml and 3 ml:9 ml bupivacaine showed no statistically significant differences in cephalad spread. A volume-dependent increase in segmental spread was between the 2 ml (0.75%) and 3 ml (0.5%) bupivacaine. The same statistically significant differences were between the 2 ml and 6 ml groups and the 2 ml and 9 ml groups. No statistically significant difference in cephalad spread resulted from increasing the dose of bupivacaine from 7.5 mg to 22.5 mg. Earlier studies on the effects of changes in volume, concentration and dose of bupivacaine showed similar "jumps of blockade" between 2 ml and 3 ml injected volume. Assembling the results the relation between volume and total dose does not suggest a no linear dependence. The anatomic configuration of the spinal cord at the conus medullaris may affect the distribution of the solution.

Unanimity has not yet been reached on the influence of injection speed and needle size on the spread of sensory blockade in spinal anesthesia. While McClure et al. [6] proved that a change in injection speed had no effect on the spread of the blockade, Lanz et al. [4] showed in their investigation that increasing injection speed increases the spread of the blockade. The influence of needle size has hardly been investigated so far. Moore et al. [7] report that the needle size alone has no effect on the spread of the blockade. In this study the influence of injection speed and that of needle size on spread of sensory blockade were considered separately. MATERIALS AND METHODS. Spinal puncture was performed via the midline approach at the L3-4 interspace with the patient in a sitting position. Immediately after the induction of anesthesia the patients were placed in the supine position again. As local anesthetic 15 mg (3 ml) bupivacaine 0.5% with epinephrine 1:200000 was administered. The aim of the study was to find out how far injection speed and size of the spinal needle influenced the sensory spread in isobaric spinal anesthesia. The height of sensory blockade was assessed by means of the pin-prick method in the midline, and the onset of analgesia was determined as height of spread. The injection speeds for the local anesthetic solution were 0.25, 0.5 and 1 ml per second. The needle sizes were 22, 25, and 29 gauge. Each group consisted of 15 patients. RESULTS. It turned out that slow (0.25 ml/s) and the fast (1 ml s) injection was associated with a significantly higher level of analgesia than the medium one (0.5 ml/s). Cephalad spread was to T7 in the first two groups, while the medium injection speed only achieved a level of T9. The results are statistically significant (P less than 0.05). The comparison of different needle sizes (22, 25, and 29 gauge) used for spinal anesthesia showed a higher spread of the sensory blockade with increased diameter of the spinal needle given a constant injection speed. With the 22-gauge needles (n = 15) sensory blockade extended on average to T7, with 25-gauge needles (n = 15) to T9, and with 29-gauge needles (n = 15) to T10. It has to be mentioned, however, that with the 29-gauge needle the standard injection speed of 0.5 ml/s could not be achieved because of the small inner diameter. The differences between 22- and 25-gauge needles are statistically significant (P less than 0.05). DISCUSSION. No direct relation could be proved between the different injection speeds and the spread of the blockade. Our results are hardly comparable with those of other investigators, since other groups have used different local anesthetics or performed investigations in vitro. The use of large spinal needles is associated with spread of the spinal block to a significantly higher level than is achieved with thinner needles.(ABSTRACT TRUNCATED AT 400 WORDS)

A selection of nine instruments supplied by eight different manufacturers for carrying out peripheral nerve stimulation were checked for their suitability, safety and ease of operation, and were compared and contrasted with reference to a spectrum of characteristics that appear desirable in theoretical and practical terms. Measurements at Ohm's resistance showed that in the clinically relevant range of impulse amplitudes (0.1-1.0 mA) the quality of adjustment of the instruments varied widely. The actual electrical impulse delivered by some of the instruments deviated so widely from the adjusted theoretical value that they must be regarded as unsuitable. The duration of the impulse corresponded to the manufacturer's specifications for only two instruments. Four instruments did not generate a monophasic square-wave signal despite assertions to the contrary in the instructions for use, and one instrument did generate such a signal although a "special biphasic asymmetrical" impulse is described by the manufacturer. Impulse-like overshooting at the beginning of the signal, oscillations into the positive range at the end of the signal and fall in current during the course of the signal were the form variants indicating technically inadequate design in the other instruments. Resistance to the square-wave current impulse engendered by the complex body resistance (impedance), a good approximation to the mathematical e-function to be expected, could be demonstrated for the rising signal flank, whereas the signal curve in the lower part of the descending flank was flatter than expected owing to polarization effects in the body tissue. The characteristic voltage and time values calculated for the signal curves are shown in tables.(ABSTRACT TRUNCATED AT 250 WORDS)

Two prospective studies were performed to assess for how long after the subarachnoid injection of local anesthetics changes in position influence the cephalad spread of sensory blockade. Divergent accounts have been given by other groups. Besides the patient's position other factors may influence the cephalad spread of sensory blockade such as baricity of local anesthetics, speed of injection, dose, volume, barbotage and size of needle. Pashalidou found that after a supine position for 5 or 10 min, followed by Trendelenburg position for 5 or 10 min, there were significant differences in the increase of sensory blockade; the following two prospective studies were carried out with this in mind. METHODS AND MATERIAL. Study 1. Injection of the local anesthetics in sitting position, puncture at L3/4 interspace using a 25-gauge needle, speed of injection 3 ml/10 s, without barbotage. After injection the patients were supine for 30 min, then changing to the Trendelenburg position (n = 20) or the lithotomy position (n = 20), each for 20 min. The spread of blockade was tested by means of pin-pricks in the midline at 5-min intervals. Local anesthetics used were bupivacaine 0.5% with adrenaline (1:200,000) (n = 20) and bupivacaine 0.5% in 8% glucose (n = 20), 3 ml each. Study 2. Intrathecal injection was done as described above, but the speed of injection was 3 ml/6 s. Local anesthetics used were bupivacaine 0.5% with adrenalin (1:200,000) and bupivacaine 0.5% with adrenalin (1:200,000) in 5% glucose, 3 ml each. The patients were kept supine for either 15 or 20 min followed by 20 degrees Trendelenburg position for 10 min. RESULTS. Study 1. The mean spread of sensory blockade with isobaric bupivacaine was 16.95 segments (T6). After the 20 degrees Trendelenburg position the spread of blockade increased by 0.85 segments. After the lithotomy position there was no increase in sensory blockade. With hyperbaric bupivacaine the mean spread of sensory blockade after 30 min in the supine position was 17.3 segments (T5/6). After the Trendelenburg position there was no increase in sensory blockade. After the lithotomy position the sensory blockade spread by 0.4 more segments. This shows that there is no significant increase of cephalad spread of sensory blockade with either isobaric or hyperbaric bupivacaine. Study 2. With isobaric bupivacaine the mean spread of sensory blockade (n = 15) after 15 min in the supine position was 14.4 segments (T8/9). Following the Trendelenburg position the caphalad spread was increased by 0.93 segments (p less than 0.05). With hyperbaric bupivacaine the mean spread of sensory blockade (n = 15) was 16 segments (T7). Following the Trendelenburg position the spread was extended by 2.0 segments (p less than 0.05). After 20 min in the supine position following isobaric bupivacaine the mean spread of the sensory blockade (n = 15) was 15.4 segments (T7/8).(ABSTRACT TRUNCATED AT 400 WORDS)