Regional-Anaesthesie最新文献

Ten urological patients with spinal anesthesia were sedated with midazolam 0.03 mg/kg i.v. A similar group (n = 10) was given placebo instead of midazolam (2 ml 0.9% NaCl). Patients who received midazolam slept lightly but were rousable. During the operation 2 l/min oxygen was administered via a nasal cannula; pO2 and pCO2 remained within normal limits throughout the procedure. No cardiovascular side effects such as hypotension or other reaction such as vomiting, nausea, or confusion were observed after midazolam. At the end of the operation all patients were fully awake and cooperative.

A case of an involuntarily placed subdural catheter (between arachnoid and dura) is described. The catheter was thought to be in the epidural space. It was placed at T9/10 in order to achieve postoperative epidural analgesia in a patient with colonic surgery. Administration of 4 ml bupivacaine 0.5% was followed by segmental analgesia (left: C7 to T9, right: T2 to T8) 10 min later. The systolic blood pressure fell from 85 to 50 mmHg. No motor block was detectable. After 150 min remission of analgesia was complete. All effects were reproducible. Using 1.3 ml of a radiopaque fluid, a spinal X-ray film showed a typical subdural picture with radiopacity detectable on the left from C8 to T8 and on the right from T1 to T7. An additional 2.7 ml did not visualize the lumbar subdural space as well. No radiopaque fluid entered the epidural or intrathecal space. It may be that accidental subdural catheter placement in regional anesthesia is not as rare as it was thought to be a few years ago. There is at present no available epidural technique that guarantees the avoidance of this complication. In addition, the symptoms of 'subdural analgesia' vary to a great extent. Therefore, the diagnosis can only be verified by X-ray examination. If patients with epidural analgesia are supervised with care and uncommon dose responses are recognized, subdural catheter placement will not lead to a severe and dangerous situation for the patient.

This study compared maternal and fetal stress responses during cesarean section in either general anesthesia (GA) or epidural anesthesia (EA). Ten patients received GA with thiopental induction, intubation, and controlled ventilation with nitrous oxide and oxygen. After delivery, anesthesia was supplemented with fentanyl 0.2-0.3 mg. Ten patients received EA via catheter, using bupivacaine 0.5%, and prilocaine or lidocaine 1%. Maternal mean arterial pressure (MAP), HR, and plasma concentrations of epinephrine and norepinephrine (by HPLC/ECD), ADH, ACTH and cortisol (by RIA) were determined before and after induction, after delivery, at the end of the operation and 30 minutes postoperatively. Fetal catecholamine levels in umbilical artery blood were measured immediately after delivery. In addition, fetal blood gas analyses and Apgar scores were compared. Fetal epinephrine was slightly increased in the EA group (EA 132 pg/ml, GA 52 pg/ml). Norepinephrine was similar in both groups (EA 1.218 pg/ml, GA 1.124 pg/ml). Blood gas analyses and Apgar scores were also comparable. A negative correlation was found between norepinephrine and pH values in fetal umbilical artery blood (P = 0.01). Maternal epinephrine levels were lower under EA and below the normal range (EA 23 pg/ml, GA 77 pg/ml, P = 0.002); levels increased during GA and decreased during EA (P = 0.01). No statistical differences were seen in maternal norepinephrine (EA 206 pg/ml, GA 354 pg/ml). MAP was lower during EA (group levels EA 81 mmHg, GA 95 mmHg, P = 0.0002) and HR was higher during GA (group levels EA 89/min, GA 104/min, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of epidural anesthesia are uncommon, but lesions are possible without technical failure. Neurological symptoms increase progressively with spinal cord compression; early recognition and treatment are imperative. Operative decompression is in most cases the only therapeutic option. This case report aims to call attention to the possibility of epidural hematoma following epidural anesthesia.

Tetrodotoxin (TTX) has been presented as an ultra-long-acting local anesthetic. Because its duration of action on myelinated nerve fibers of warm-blooded animals is unknown the effect of TTX on natural spike activity (A-delta fibers) of rabbit aortic nerve in vivo was studied. In 13 animals, a segment of the aortic nerve was placed in a perfusion chamber and exposed to increasing concentrations of TTX (n = 8) and, for comparison, of procaine (n = 8), which like TTX has a high pka. Total nerve activity and its change as related to drug concentrations was recorded continuously (concentration effect curves). The half-lives (t1/2) of onset time after drug administration and recovery following drug washout were also determined. TTX blocked nerve activity in a concentration-related manner, as did procaine; however, the potency of TTX (EC50 = 3.3 +/- 0.8.10(-9), cm = 1.3 +/- 0.4.10(-8) mol/l) was about 50,000 times higher than that of procaine (EC50 = 1.6 +/- 0.2.10(-4), cm = 2.5 4/- 0.3.10(-4) mol/l). Onset time did not differ statistically (p = 0.08) between TTX (t1/2 = 3.5 +/- 0.4 min) and procaine (t1/2 = 2.2 +/- 0.5 min). Most importantly, TTX block could not be reversed within 1-5 h of drug washout (n = 5) or was reversed incompletely (13%, 66%, and 90% of control activity) with t1/2 16 to 21 min. In contrast, all the procaine-blocked nerves recovered completely (t1/2 = 3.0 +/- 0.4 min). TTX blocks myelinated A-delta fibers of warm-blooded animals with lower concentrations and for a longer time than nonmyelinated fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

The advantages of an electrical nerve stimulator for detection of the axillary neurovascular sheath have been frequently described in the literature and are now well known. In most of these techniques, stimulation is achieved by a fixed electrical voltage and variable amplification. The new nerve stimulator presented here offers the possibility of measuring the current at the site of stimulation ("test" position). PATIENTS AND METHODS. Axillary block was performed in 23 patients undergoing orthopedic surgery. Identification of the neurovascular sheath was first achieved by the "loss of resistance" technique, after which the injection cannula was connected to the new device. Stimulation was started at 1.0 mA. In case of a negative response to stimulation the actual electric current was checked by means of the test position in order to exclude an error in the circuit system. In these cases, the position of the cannula was altered so as to maintain a response at the lowest possible current (less than 0.5 mA). After removal of the inner solid steel stylet of the cannula, the local anesthetic was injected while compressing the distal part of the neurovascular sheath in order to avoid downstream diffusion. RESULTS. All 23 patients were operated upon under axillary block after nerve stimulator control without any additional drugs. Table 2 indicates the lowest stimulation current that still evoked a response. Disturbances in the circuit system were found twice, one caused by a short circuit, the other by a desiccated gel pad on the adhesive electrode. After elimination of the defect, stimulation produced a response. DISCUSSION. Since it is now well known that induction of paresthesias in locating peripheral nerves can cause irreversible lesions, the use of electrical nerve stimulators is preferred to locate the cannula as near as possible to the nerve without direct contact. The mode of operation of the stimulator presented here, which defines the chosen technical starting impulse as well as the actual current, allows much better localization of nerves during local anesthesia. Thus, disturbances in the circuit between nerve stimulator and patient, as shown in the two cases, can be detected. According to our experience, the intensity of stimulation for successful nerve blockade should be approximately 0.5 mA or lower. Consequently, universally applicable stimulating instruments with constant electrical tension should allow fine tuning of the current in 0.1-mA aliquots.

The use of high epidural anesthesia for cesarean section has generally been accepted as a safe and comfortable means of intra- and post-operative pain relief in recent years. However, the accompanying vasomotor blockade of the lower body and the sometimes impaired cardiac reflex activity restrict the use of concomitant--even local--medication. Described are the deleterious side effects on hemodynamic stability and patient comfort of an intramyometrically administered synthetic prostaglandin E (PGE2)-compound (dinoprostone) given to three female patients under high epidural anesthesia during cesarean section. Differentiation of the various symptoms is made in relation to their epidural or PGE origin or to a combination of the two. A striking therapeutic resistance of the hypotension of a sufficiently volume-expanded patient to even large doses of ephedrine is discussed as representing possible PGE-mediated suppression of peripheral norepinephrine release.

A lack of uniform methodology used in the assessment of different injection speeds in spinal anesthesia by different authors formed the basis of the current study, which compared under randomized conditions the effects of various injection speeds during intrathecal administration of 4 ml 0.5% hyperbaric bupivacaine or 0.5% hyperbaric tetracaine. MATERIALS AND METHODS. Eighty male ASA Physical Status II and III patients scheduled for transurethral resection of the prostate under spinal anesthesia were selected. They were randomly divided into four groups of 20 each. Patients were given 4 ml of either 0.5% hyperbaric bupivacaine or 0.5% hyperbaric tetracaine according to the following scheme: I: 4 ml tetracaine/0.25 ml.s-1; II: 4 ml tetracaine/0.5 ml.s-1: III: 4 ml bupivacaine/0.25 ml.s-1; IV: 4 ml bupivacaine/0.5 ml.s-1. The study was carried out in a double-blind fashion and puncture was performed at the L3-4 interspace using a 25-gauge needle with the patient in the sitting position. Following injection of the anesthetic solution (0.25 ml.s-1 or 0.5 ml.s-1 without barbotage), the patient was immediately placed in the lithotomy position with the table remaining horizontal. The level of anesthesia using pin prick and the degree of motor blockade, using a 0 to 3+ scale where 0 represented no motor weakness and 3+ complete motor block, were assessed at specific intervals. Statistical analysis was performed using the Mann-Whitney rank sum test: P value of less than 0.05 was considered statistically significant. RESULTS. Bupivacaine injected at 0.25 ml.s-1 was associated with a higher dermatome level than at 0.5 ml.s-1 (P less than 0.05). Time to highest dermatome, however, was shorter with bupivacaine 0.5 ml.s-1 compared to 0.25 ml.s-1 (P less than 0.05) (Table 3, Fig. 1). Time to highest level of analgesia was shorter with tetracaine 0.25 ml.s-1 compared to 0.5 ml.s-1 (P less than 0.05) (Fig. 2). At 0.25 ml.s-1, tetracaine achieved the highest dermatome faster than bupivacaine (P less than 0.05). Tetracaine injected at 0.5 ml.s-1, however, was associated with a higher segmental level than bupivacaine (P less than 0.05). At 0.25 ml.s-1 bupivacaine and tetracaine achieved a 3+ motor block faster than at 0.5 ml.s-1 (P less than 0.05). Complete motor blockade, however, was significantly longer with tetracaine at both injection speeds (0.25 and 0.5 ml.s-1) compared to bupivacaine (P less than 0.05). CONCLUSIONS. The results suggest that 4 ml 0.5% hyperbaric bupivacaine or tetracaine injected at 0.25 or 0.5 ml.s-1 provides a rapid and reproducible spread of analgesia for transurethral surgery. However, our findings suggest that speed of injection is of little i