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Matthew R Eng,1 Paul F White1,2 1Department of Anesthesiology, Cedars-Sinai Medical Center, Los Angeles, CA, USA; 2White Mountain Institute, The Sea Ranch, CA, USA Summary statement: Advances in the use of intravenous techniques in ambulatory anesthesia has become important for the anesthesiologist as the key perioperative physician in outpatient surgery. Key techniques and choices of anesthetics are important in accomplishing fast track goals of ambulatory surgery. Purpose of review: The anesthesiologist in the outpatient environment must focus on improving perioperative efficiency and reducing recovery times while accounting for patients' well-being and safety. This review article focuses on recent intravenous anesthetic techniques to accomplish these goals. Recent findings: This review is an overview of techniques in intravenous anesthesia for ambulatory anesthesia. Intravenous techniques may be tailored to accomplish outpatient surgery goals for the type of surgical procedure and individual patient needs. Careful anesthetic planning and the application of the plans are critical to an anesthesiologist's success with fast-track ambulatory surgery. Conclusion: Careful planning and application of intravenous techniques are critical to an anesthesiologist's success with fast-track ambulatory surgery. Keywords: intravenous anesthesia, outpatient anesthesia, fast-track surgery

Closed-loop control of propofol delivery was instituted in three patients who received a propofol infusion as part of: (Case 1) general "balanced" anesthesia, (Case 2) total intravenous anesthesia, and (Case 3) monitored anesthesia care. The bispectral index was the input variable used in a proportioned, integral and differential controller to determine the infusion rate of propofol required to maintain a stable level of hypnosis (Cases 1 and 2) or sedation (Case 3). This feedback control system provided intraoperative hemodynamic stability and a prompt recovery from the sedative-hypnotic effects of propofol.

UNLABELLED This randomized, double-blind study was designed to evaluate the analgesic effectiveness and respiratory stability of remifentanil when administered as intermittent bolus injections, a variable-rate infusion, or a combination of a constant basal infusion supplemented with intermittent boluses during monitored anesthesia care (MAC). Forty-five patients undergoing extracorporeal shock wave lithotripsy (ESWL) procedures were randomly assigned to one of the three modes of remifentanil administration. All patients received midazolam 2 mg i.v., followed by a propofol infusion at 50 microg x kg(-1) x min(-1). Two minutes before administering a series of test shock waves: Group I received a remifentanil infusion of 0.1 microg x kg(-1) x min(-1), and a saline bolus (5 mL); Group II received a saline infusion and a remifentanil bolus (25 microg in 5 mL); and Group III received a remifentanil infusion of 0.05 microg x kg(-1) x min(-1), and a remifentanil bolus (12.5 microg in 5 mL). The average pain intensity was scored on an 11-point scale, with 0 = no pain to 10 = severe pain. During the ESWL procedure, pain was treated by increasing the study drug infusion rate by 25%-50% and administering 5-mL bolus injections of the study medication in Groups I (saline) and II (remifentanil 25 microg). In Group III, intermittent 5-mL boluses (remifentanil 12.5 microg) were administered as needed. Patients in Groups II and III reported lower pain scores in response to the test shocks. Significantly more remifentanil was administered in Group I (379 +/- 207 microg) than in Group II (201 +/- 136 microg). However, more interventions were required for the treatment of intraoperative pain in the intermittent bolus group (Group II). When remifentanil is administered as the analgesic component of a MAC technique, these data support the use of intermittent bolus doses (12.5-25 microg) alone or in combination with a basal infusion (0.05 microg x kg(-1) x min(-1)) as alternatives to a variable-rate continuous infusion. IMPLICATIONS In this study, three different modes of remifentanil administration were used during monitored anesthesia care for extracorporeal shock wave lithotripsy procedures. These results suggest that using intermittent bolus injections of remifentanil (25 microg) or a continuous infusion (0.05 microg x kg(-1) x min(-1)) supplemented with intermittent bolus (12.5 microg) injections may be more effective than a variable-rate infusion of remifentanil during propofol sedation.

Total intravenous anesthesia (TIVA) with propofol is an alternative to standard techniques for neuroanesthesia. The present study compared the hemodynamic and recovery profiles of 46 neurosurgical patients randomly assigned to one of three different anesthetic treatment groups. Group 1 was anesthetized with a TIVA technique in which propofol was titrated using an EEG-assisted quantification method. Group 2 received a similar propofol-based infusion technique in combination with nitrous oxide. Group 3 (control) received a standard anesthetic technique consisting of thiopental, nitrous oxide, fentanyl, and isoflurane. Significantly less propofol was required in group 2 than in group 1 (7.4 +/- 1.9 vs. 9.0 +/- 1.0 mg/kg/h, respectively). The propofol blood concentration at the first appearance of EEG burst suppression was also higher in group 1 compared to group 2 (5.8 +/- 1.1 vs. 4.8 +/- 0.8 microg/ml). However, 25% of the patients in group 2 were treated for hypotension after induction, compared to none in groups 1 and 3. Hypertensive episodes, on the other hand, were more frequent in groups 1 (43%) and 3 (31%) than in group 2 (12%). Time to awakening was significantly shorter in the control group (6 +/- 6 min) than in groups 1 (14 +/- 10 min) or 2 (12 +/- 16 min). In conclusion, titration of propofol to achieve a burst suppressive EEG pattern resulted in a slower emergence from anesthesia than a standard "balanced" technique. Use of nitrous oxide with propofol produced more hypotension during induction; however, its use improved hemodynamic stability during the maintenance period.

In 97 outpatients undergoing ambulatory arthroscopic procedures, we compared esmolol with alfentanil when used to supplement propofol-N2O-atracurium anesthesia according to a randomized, double-blind protocol. After an initial intravenous dose of 16 micrograms/kg alfentanil, or 2 mg/kg of esmolol, a variable-rate infusion of alfentanil or esmolol was administered to maintain a stable heart rate. After induction of anesthesia with 2.5 mg/kg of propofol, mean arterial pressure decreased to a larger extent in the alfentanil-treated patients. Although heart rate and mean arterial pressure increased in both groups after tracheal intubation, alfentanil more effectively blunted the hemodynamic response to this stimulus. Maintenance of anesthesia was adequate in both treatment groups. After discontinuation of anesthesia, patients in the esmolol group opened their eyes earlier (7.2 +/- 2.4 min vs 9.8 +/- 4.6 min) than those in the alfentanil group. Esmolol-treated patients also reported less sedation in the first 15 min of recovery than those receiving alfentanil. However, there were no differences in times to ambulation and discharge between the groups. Esmolol-treated patients reported more postoperative pain for the first 15 min of recovery and more esmolol-treated patients required postoperative opioid analgesia than those treated with alfentanil. There were no significant differences in the incidences of nausea and vomiting between the two groups. The authors conclude that esmolol may be used in place of alfentanil to supplement propofol-N2O-atracurium anesthesia in outpatients undergoing arthroscopic procedures. However, hemodynamic responses to tracheal intubation were larger with esmolol, and avoidance of alfentanil did not decrease the incidence of postoperative nausea and vomiting in this outpatient population.

BACKGROUND: One of the most common approaches to identifying the L4-L5 interspace is using the iliac crest as a landmark. We propose a new landmark to identify the L4-L5 interspace based on the soft tissue depression palpable at the iliac crest prominence. The aim of this study was to assess the reliability and time saving when using this new landmark compared to using the iliac crest to perform a lumbar plexus block. METHODS: Fifty-four patients scheduled for lower limb surgery were randomly allocated to have a lumbar plexus block performed using the iliac crest (Chayen's approach) or the soft tissue depression (Borghi's approach). The landmarks for both approaches were drawn on each patient prior to randomization (N.=27 per group). All the blocks were performed by an anesthesiologist familiar with both techniques using a nerve stimulator and 30 mL of 0.5% levobupivacaine. The time to achieve successful needle placement and the number of needle re-directions, as well as the onset time for the sensory and motor blockade, were recorded. RESULTS: All the blocks using Borghi's approach were performed successfully. With the Chayen's approach, there were 5 needle placement failures. The mean times to onset of a successful block after injection of the local anesthetic did not differ between the two groups: 17.8±3.9 min for the Chayen vs. 15.9±2.4 min for the Borghi's approach (P=0.14). However, the mean time to achieve correct needle placement was 7.6±3.2 min with the Chayen's approach compared to 5.1 (±2.6 SD) min with the Borghi's approach (P

The purpose of the case is to report the clinical value of the ultrasound-guided posterior approach to the brachial plexus in the treatment of phantom limb syndrome after an upper extremity amputation. The author experienced ultrasound guidance as sole technique to localize the brachial plexus for the purpose of placing a catheter for continuous infusion of a local anesthetic in a patient where standard landmark-based nerve stimulation for placement of a continuous perineural block was not possible.

Phantom limb syndrome (PLS) is common after limb amputations, involving up to 90% of amputees. Although many different therapies have been evaluated, none has been found to be highly effective. Therefore, we evaluated the efficacy of a prolonged perineural infusion of a high concentration of local anesthetic solution in preventing PLS.A perineural catheter was placed immediately before or during surgery in 71 patients undergoing lower extremity amputation. A continuous infusion of 0.5% ropivacaine was started intraoperatively at 5 mL/h using an elastomeric (nonelectronic) pump, and continued for 4 to 83 days after surgery. PLS was evaluated on the first postoperative day and then 1, 2, 3, and 4 weeks, and 3, 6, 9, and 12 months after surgery. To evaluate the presence and severity of PLS while the patient was receiving the ropivacaine infusion, it was discontinued for 6 to 12 hours before each assessment period (i.e., until the sensation in the extremity returned). The severity of phantom limb and stump pain was assessed using a 5-point verbal rating scale (VRS), with 0 = no pain to 4 = intolerable pain, and "phantom" sensations were recorded as present or absent. If the VRS score was1 or significant phantom sensations were present, the ropivacaine infusion was immediately restarted at 5 mL/h. If the VRS score remained at 0 to 1 and the patient had not experienced phantom sensations for 48 hours, the infusion was permanently discontinued and the catheter was removed.Median duration of the local anesthetic infusion was 30 days (95% confidence interval, 25-30 days). On postoperative day 1, 73% of the patients complained of severe-to-intolerable pain (visual analog scale2). However, the incidence of severe-to-intolerable phantom limb pain was only 3% at the end of the 12-month evaluation period. At the end of the 12-month period, the percentage of patients with VRS pain scores were 0 = 84%, 1 = 10%, 2 = 3%, 3 = 3%, and 4 = none. However, phantom limb sensations were present in 39% of patients at the end of the 12-month evaluation period. All patients were able to manage the elastomeric catheter infusion system at home.Use of a prolonged postoperative perineural infusion of ropivacaine 0.5% seems to be an effective therapy for the treatment of phantom limb pain and sensations after lower extremity amputation.