Christian Weinstabl

Ultrasonographic Guidance Improves Sensory Block and Onset Time of Three-in-One Blocks

The use of ultrasound reduces the onset time, improves the quality of sensory block, and minimizes the risks associated with the supraclavicular approach for brachial plexus and stellate ganglion blockade.The present study was designed to evaluate whether ultrasound also facilitates the approach for 3-in-1 blocks. Forty patients (ASA physical status II or III) undergoing hip surgery after trauma were randomly assigned to two groups. In the ultrasound (US) group, 20 mL bupivacaine 0.5% was administered under US guidance, whereas in the control group, the same amount and concentration of local anesthetic was administered with the assistance of a nerve stimulator (NS). After US- or NS-based identification of the femoral nerve, the local anesthetic solution was administered, and the distribution of the local anesthetic solution was visualized and recorded on videotape in the US group. The quality and the onset of the sensory block was assessed by using the pinprick test in the central sensory region of each of the three nerves and compared with the same stimulation on the contralateral leg every 10 min for 60 min. The rating was performed using a scale from 100% (uncompromised sensibility) to 0% (no sensory sensation). Heart rate, noninvasive blood pressure, and oxygen saturation were measured at short intervals for 60 min. The onset of sensory blockade was significantly shorter in Group US compared with Group NS (US 16 +/- 14 min, NS 27 +/- 16 min, P < 0.05). The quality of the sensory block after injection of the local anesthetic was also significantly better in Group US compared with Group NS (US 15% +/- 10% of initial value, NS 27% +/- 14% of initial value, P < 0.05). A good analgesic effect was achieved in 95% of the patients in the US group and in 85% of the patients in the NS group. In the US group, visualization of the cannula tip, the femoral nerve, the major vessels, and the local anesthetic spread was possible in 85% of patients. Incidental arterial puncture (n = 3) was observed only in the NS group. We conclude that an US-guided approach for 3-in-1 block reduces the onset time, improves the quality of the sensory block and minimizes the risks associated with this regional anesthetic technique. Implications: The onset time and the quality of a regional anesthetic technique for the lower extremity is improved by ultrasonographic nerve identification compared with older techniques. (Anesth Analg 1997;85:854-7)

Ultrasound-guided supraclavicular approach for regional anesthesia of the brachial plexus.

We prospectively studied 40 patients (ASA grades I-III) undergoing surgery of the forearm and hand, to investigate the use of ultrasonic cannula guidance for supraclavicular brachial plexus block and its effect on success rate and frequency of complications. Patients were randomized into Group S (supraclavicular paravascular approach; n = 20) and Group A (axillary approach; n = 20). Ultrasonographic study of the plexus sheath was done. After visualization of the anatomy, the plexus sheath was penetrated using a 24-gauge cannula. Plexus block was performed using 30 mL bupivacaine 0.5%. Onset of sensory and motor block of the radial, ulnar, and median nerves was recorded in 10-min intervals for 1 h. Satisfactory surgical anesthesia was attained in 95% of both groups. In Group A, 25% showed an incomplete sensory block of the musculocutaneous nerve, whereas all patients in Group S had a block of this nerve. Complete sensory block of the radial, median, and ulnar nerves was attained after an average of 40 min without a significant difference between the two groups. Because of the direct ultrasonic view of the cervical pleura, we had no cases of pneumothorax. An accidental puncture of subclavian or axillary vessels, as well as neurologic damage, was avoided in all cases. An ultrasonography-guided approach for supraclavicular block combines the safety of axillary block with the larger extent of block of the supraclavicular approach.

Tramadol added to mepivacaine prolongs the duration of an axillary brachial plexus blockade.

UNLABELLED Tramadol is an analgesic drug that is antagonized by alpha2-adrenoceptor antagonists, as well as opioid antagonists. We hypothesized that tramadol might produce effects on an axillary brachial plexus blockade similar to those of clonidine. We designed a prospective, controlled, double-blinded study to assess the impact of tramadol added to mepivacaine on the duration of an axillary brachial plexus blockade. After institutional approval and informed consent, 60 patients (ASA physical status I or II) scheduled for forearm and hand surgery after trauma under brachial plexus anesthesia were included in the study. Patients were randomly assigned to receive either 40 mL of mepivacaine 1% with 2 mL of isotonic sodium chloride solution (Group A, n = 20); 40 mL of mepivacaine 1% with 100 mg of tramadol (Group B, n = 20); or 40 mL of mepivacaine 1% with 2 mL of isotonic sodium chloride solution and 100 mg of tramadol i.v. (Group C, n = 20). Sensory block, motor block, and hemodynamics were recorded before and 5, 10, 30, 60, 120, 180, and 360 min after local anesthetic injection. Duration of sensory and motor block was significantly longer (P < 0.01; P < 0.05) in Group B (299 +/- 84 and 259 +/- 76 min) than in Group A (194 +/- 35 and 181 +/- 24 min) and Group C (187 +/- 35 and 179 +/- 16 min). There was no difference in onset of sensory and motor blockade among groups. Hemodynamics remained unchanged in all patients throughout the study period. We conclude that the addition of tramadol prolongs the duration of brachial plexus block without side effects. Tramadol may be an alternative to epinephrine or clonidine as an adjuvant to local anesthesia for an axillary block. IMPLICATIONS This study demonstrates that the admixture of 100 mg of tramadol with mepivacaine 1% for brachial plexus block provides a pronounced prolongation of blockade without side effects. Our data support a specific analgesic effect of tramadol on peripheral nerves.

Lateral infraclavicular plexus block vs. axillary block for hand and forearm surgery

Background: In the last few years infraclavicular plexus block has become a method of increasing interest. However, this block has been associated with high complication incidences and without advantage in the quality of blockade over the axillary approach. We prospectively studied 40 patients (ASA I–III) undergoing surgery of the forearm and hand, and investigated the performance of the lateral infraclavicular plexus block against an axillary paravascular block to evaluate the success rate as well as the extent and quality of blockade.

Hemodynamic and analgesic effects of clonidine added repetitively to continuous epidural and spinal blocks.

Clonidine in spinal and epidural blocks prolongs anesthesia, but can cause hypotension and bradycardia.The aim of our study was to compare hemodynamic and analgesic effects of spinal versus epidural clonidine alone and after repetitive dosing. In a prospective, randomized, double-blind study, we evaluated 40 patients scheduled for lower extremity orthopedic surgery under continuous spinal or epidural anesthesia with bupivacaine 0.5% (initial dose 5 mg and 50 mg, respectively). In either spinal or epidural technique one-half of patients received clonidine (150 micro gram) in addition to bupivacaine. Repeat doses of the same anesthetic mixture were allowed in cases of subsequent pain. Mean arterial pressure (MAP) and heart rate were recorded for 6 h after each injection. Duration of clinically useful anesthesia was defined as the time from drug administration to first sensation of pain. Intrathecal, but not epidural, clonidine decreased MAP significantly compared with bupivacaine alone. MAP after intrathecal clonidine with bupivacaine was lower than epidural clonidine with bupivacaine 5 and 6 h after injection. Repetitive administration caused no further decrease in MAP. Onset time required to surgical anesthesia (sensory block of T11) did not differ among the four groups. Duration of spinal and epidural anesthesia was increased more than two fold by clonidine. In summary, the addition of clonidine prolongs analgesia by either route. These results may be explained by clonidines sites of action in hemodynamic control and the density of bupivacaine-induced block. (Anesth Analg 1995;80:322-7)

Spinal versus general anesthesia for orthopedic surgery : Anesthesia drug and supply costs

Total hip or knee replacement surgeries are common orthopedic interventions that can be performed with spinal anesthesia (SA) or general anesthesia (GA). No study has investigated the economic aspects associated with the two anesthetic techniques for this common surgery. We randomized 40 patients to receive either SA or GA and analyzed the drug and supply costs for anesthesia und recovery. Anesthesia-related times, hemodynamic variables, and pain scores were also recorded. Total costs per case without personnel costs were almost half in the SA group compared with the GA group; this was a result of less cost for anesthesia (P < 0.01) and for recovery (P < 0.05). This finding was supported by a sensitivity analysis. There were no relevant differences regarding anesthesia-related times. Patients in the GA group were admitted to the postanesthesia care unit with a higher pain score and needed more analgesics than patients in the SA group (both P < 0.01). We conclude that SA is a more cost-effective alternative to GA in patients undergoing hip or knee replacement, as it is associated with lower fixed and variable costs. Moreover, SA seems to be more effective, as patients in the SA group showed lower postoperative pain scores during their stay in the postanesthesia care unit.

Continuous Spinal Anesthesia with a Microcatheter and Low-Dose Bupivacaine Decreases the Hemodynamic Effects of Centroneuraxis Blocks in Elderly Patients

This prospective randomized study was designed to investigate the hemodynamic effects and quality of continuous spinal anesthesia (CSA) after rapid injection of a low dose of 0.5% bupivacaine through a 32-gauge microcatheter. The method was compared with continuous epidural (CEA) and single-dose spinal anesthesia (SSA). Seventy-seven elderly patients (ASA II-III) ranging from 57 to 94 yr old and undergoing lower limb surgery were assigned to CSA (n = 26), CEA (n = 26), and SSA groups (n = 25). In all three groups, mean arterial pressure (MAP) and heart rate (HR) were assessed continuously for 30 min after initial injection, as well as after every reinjection of local anesthetic in the CSA and CEA groups. Bupivacaine (0.5%) was used as a local anesthetic. The initial doses were 1 mL of CSA, 10 mL of CEA, and 3 mL of SSA. The reinjection doses were 1 mL of CSA and 5 mL of CEA. In the CSA group, MAP did not decrease, whereas in the CEA group, the maximum decrease was 15% +/- 3% (mean +/- SEM) for the initial injection, 12% +/- 2% for the first repetition, and 13% +/- 2% for the second repetition. In the SSA group, the largest decrease of MAP was 19% +/- 2%. All changes of MAP in the CEA and SSA groups were significantly larger compared with CSA group (P < 0.05). A total of seven patients in these two groups needed vasopressors due to a decrease of MAP of more than 30% from baseline values. Heart rate did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of thoracic epidural anesthesia on intraoperative visceral perfusion and metabolism.

UNLABELLED After institutional approval and informed consent, we studied the effect of epidural bupivacaine 0.5% on visceral perfusion and metabolism by using gastric mucosal tonometry in 30 patients in a placebo-controlled fashion. The maximal intramucosal pH (pHi) decrease was significantly (P < 0.001) greater in the control group (0.16 +/- 0.04) than in the thoracic epidural anesthesia (TEA) group (0.07 +/- 0.05). There were 10 patients in the control group and 2 patients in the TEA group who had evidence of gastric mucosal ischemia (pHi <7.32) at the end of the study (P< 0.01). The differences in pHi and intramucosal CO2 (PiCO2) became statistically significant between the groups after 180 and 240 min. The study data show that TEA prevents the decrease of pHi during major abdominal surgery, perhaps as an effect of stable visceral perfusion. We conclude that TEA may be a valuable method for intra- and postoperative treatment of surgical stress. IMPLICATIONS The present study shows that thoracic epidural anesthesia prevents a decrease of intramucosal pH during major abdominal surgery, which suggests that thoracic epidural anesthesia may be a valuable tool for the treatment of surgical stress.

Excursions of the cervical spine during tracheal intubation: blind oral intubation compared with direct laryngoscopy

The most appropriate technique for performing tracheal intubation in patients with cervical spine injury is debatable. Recently, a new device enabling blind oral intubation (Augustine GuideTM) with the patients head and neck in the neutral position has been introduced. The aim of this study was to compare the extent of upper cervical spine movement during intubation with this device compared to direct laryngoscopy. Twelve patients (Mallampati I and II), without a cervical spine injury, were intubated using the Augustine GuideTM and afterwards by direct laryngoscopy. Both procedures were viewed radiographically. Extension in the upper cervical spine was determined at the point of the maximum excursion. By evaluating the joints occiput‐C3 together as a functional unit, blind oral intubation caused 17° (median) less extension compared to direct laryngoscopy (p < 0.01). The median differences observed for the individual joints were: 7° in occiput‐C1 (p < 0.05), 5° in C1‐2 (p < 0.01) and 6° in C2‐3 (p < 0.01) respectively. Since we assume that intubation‐induced excursions of the injured spine are even higher, blind oral intubation might be a safe alternative for airway management in this special group of trauma victims.

Effect of sufentanil on intracranial pressure in neurosurgical patients

The effects of sufentanil on intracranial pressure, mean arterial pressure, cerebral perfusion pressure and heart rate were studied in 20 neurosurgical intensive care unit patients. Epidural intracranial pressure probes were implanted in patients who suffered head injury, intracerebral haemorrhage or underwent tumour resection. Sufentanil was given intravenously in sequential doses of 0.5, 1.0 and 2.0 μg/kg. Fifteen minutes elapsed after each dose. The patients were allocated to either group 1 (baseline intracranial pressure < 20 mmHg) or group 2 (baseline intracranial pressure > 20mmHg). Intracranial pressure did not change significantly in either group. Therefore the falls in mean arterial pressure with the highest dose in both groups and with 1.0 μg/kg in group 2, closely reflect corresponding reductions in cerebral perfusion pressure. As sufentanil in itself exerts no effects on intracranial pressure, concomitant haemodynamic changes are the critical factor for an adequate cerebral perfusion pressure.