Stephen M. Klein

Thoracic paravertebral block for breast surgery.

Cosmetic and reconstructive breast augmentation is a frequently performed surgical procedure. Despite advances in medical treatment, surgical intervention is often associated with postoperative pain, nausea, and vomiting. Paravertebral nerve block (PVB) has the potential to offer long-lasting pain relief and fewer postoperative side effects when used for breast surgery. We compared thoracic PVB with general anesthesia for cosmetic breast surgery in a single-blinded, prospective, randomized study of 60 women scheduled for unilateral or bilateral breast augmentation or reconstruction. Patients were assigned (n = 30 per group) to receive a standardized general anesthetic (GA) or thoracic PVB (levels T1–7). Procedural data were collected, as well as verbal and visual analog pain and nausea scores. Verbal postoperative pain scores were significantly lower in the PVB group at 30 min (P = 0.0005), 1 h (P = 0.0001), and 24 h (P = 0.04) when compared with GA. Nausea was less severe in the PVB group at 24 h (P = 0.04), but not at 30 min or 1 h. We conclude that PVB is an alternative technique for cosmetic breast surgery that may offer superior pain relief and decreased nausea to GA alone. Implications Paravertebral nerve block has the potential to offer long-lasting pain relief and few postoperative side effects when used for breast surgery. We demonstrated that paravertebral nerve block, when compared with general anesthesia, is an alternative technique for breast surgery that may offer pain relief superior to general anesthesia alone.

Interscalene brachial plexus block with a continuous catheter insertion system and a disposable infusion pump.

Continuous interscalene brachial plexus blockade traditionally requires a hospital stay for local anesthetic infusion, and achieving consistent catheter insertion may be difficult. Incorporating long-acting pain relief from a continuous peripheral nerve block, with a reliable method of catheter insertion, and a self-contained infusion system would be a valuable asset for short-stay care. We compared the efficacy of single injection interscalene brachial plexus blockade to a continuous peripheral nerve block, with an insulated Tuohy system and a disposable infusion pump. Forty adult patients scheduled for open rotator cuff repair were entered in this randomized, double-blinded, placebo-controlled study. Patients received an interscalene brachial plexus blockade and a continuous peripheral nerve catheter as their primary anesthetic and then, were assigned to receive one of two different postoperative infusions: either 0.2% ropivacaine at 10 mL/h via a disposable infusion pump or normal saline at 10 mL/h via a disposable infusion pump (n = 18–20 per group). Visual analog pain scores and postoperative morphine consumption were measured for 24 h. The ropivacaine group showed less pain than the placebo group (P = 0.0001) between 12 and 24 h after the initial injection of local anesthetic. In addition, initial interscalene blockade was successful in all patients and all redosed catheters were functional after 24 h with the continuous catheter insertion system. We conclude that it is possible to achieve a high rate of successful catheter placement and analgesia by using the continuous catheter insertion system and a disposable infusion pump in the ambulatory setting. This method of analgesia may offer improved pain relief after outpatient rotator cuff repair. Implications This study demonstrates that it is possible to achieve successful interscalene brachial plexus continuous catheter insertion and a high degree of persistent analgesia by using a catheter insertion system and a disposable infusion pump administering 0.2% ropivacaine.

Continuous peripheral nerve block for ambulatory surgery.

Background and Objectives Adenosine is an endogenous compound that may have analgesic effects. Results from clinical trials are not consistent, however, and there is a need for large-scale, randomized, placebocontrolled studies to clarify the role of adenosine in the treatment of pain states, including acute nociceptive pain and pain involving central sensitization. Methods The analgesic and antihyperalgesic effect of systemic adenosine on the heat/capsaicin sensitization model of experimental pain was investigated in 25 healthy human volunteers. Sensitization was produced by heating the skin to 45°C for 5 minutes, followed by a 30-minute application of 0.075% capsaicin cream, and maintained by periodically reheating the sensitized skin to 40°C for 5 minutes at 40-minute intervals. Subjects received intravenous adenosine 60 μg/kg/min or saline for 85 minutes. Areas of secondary hyperalgesia to von Frey hair and brush stimulation, heat-pain detection thresholds (HPDTs) in normal and sensitized skin, and painfulness of stimulation with 45°C for 1 minute (LTS) in normal skin were quantified before, during, and after study drug infusion. Results Systemic adenosine had no effect on the area of secondary hyperalgesia to von Frey hair or brush stimulation, HPDT in normal or sensitized skin, or painfulness of LTS in normal skin. Conclusion We conclude that adenosine has no effect on acute nociceptive pain induced by heat stimulation or on secondary hyperalgesia induced by heat/capsaicin sensitization in healthy volunteers.

Ambulatory discharge after long-acting peripheral nerve blockade: 2382 blocks with ropivacaine.

Discharging patients with a long-acting peripheral nerve block remains controversial. Concerns about accidental injury of the limb or surgical site because of an insensate extremity are common despite a lack of data on the subject. We report a study examining the efficacy and complications of discharge after long-acting block. This prospective study included 1791 patients receiving an upper or lower extremity nerve block with 0.5% ropivacaine and discharged the day of surgery. Efficacy (conversion to general anesthesia and opioid use), persistent motor or sensory weakness, complications, satisfaction, and unscheduled health care visits were assessed in the postanesthesia care unit (PACU) and at 24 h and 7 days postoperatively using a detailed questionnaire. There were 2382 blocks placed: 1119 upper extremity blocks and 1263 lower extremity blocks. Efficacy was demonstrated by a small conversion to general anesthesia (1%–6%) and a lack of patients requiring opioids in the PACU (89%–92%). A large percentage of patients continued to use opioids at 7 days (17%-22%). Despite the requirement for opioids, satisfaction with the anesthesia experience was high at 24 h and 7 days (Liekert scale [1–5] mean at 24 h, 4.88 ± 0.44; mean at 7 days, 4.77 ± 0.69) and most (98%) would choose the same anesthetic again. Thirty-seven patients (1.6%) were identified with symptoms or complaints at 7 days. After review, 6 of them (0.25%) had a persistent paresthesia that may have been related to the block or discharge. We conclude that long-acting peripheral nerve blockade may be safely used in the ambulatory setting with a high degree of efficacy, safety, and satisfaction. This technique is associated with an infrequent incidence of neurologic complications and injuries. Given the frequent incidence of persistent pain at 7 days, prolongation of the analgesia would be beneficial.

A comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block

The onset time and duration of action of ropivacaine during an interscalene block are not known.The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. Implications: In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block. (Anesth Analg 1998;87:1316-9)

Influence of Obesity on Surgical Regional Anesthesia in the Ambulatory Setting: An Analysis of 9,038 Blocks

Background: Regional anesthesia is increasing in popularity for ambulatory surgical procedures. Concomitantly, the prevalence of obesity in the United States population is increasing. The objective of the present investigation was to assess the impact of body mass index (BMI) on patient outcomes after ambulatory regional anesthesia. Methods: This study was based on prospectively collected data including 9,038 blocks performed on 6,920 patients in a single ambulatory surgery center. Patients were categorized into three groups according to their BMI (<25 kg/m2, 25–29 kg/m2, ≥30 kg/m2). Block efficacy, rate of acute complications, postoperative pain (at rest and with movement), postoperative nausea and vomiting, rate of unscheduled hospital admissions, and overall patient satisfaction were assessed. Linear and logistic multivariable analyses were used to obtain the risk-adjusted effect of BMI on these outcomes. Results: Of all patients 34.8% had a BMI <25 kg/m2, 34.0% were overweight (BMI 25–29 kg/m2), and 31.3% were obese (BMI ≥ 30 kg/m2). Patients with BMI ≥30 kg/m2 were 1.62 times more likely to have a failed block (P = 0.04). The unadjusted rate of acute complications was higher in obese patients (P = 0.001). However, when compared with patients with a normal BMI, postoperative pain at rest, unanticipated admissions, and overall satisfaction were similar in overweight and obese patients. Conclusions: The present investigation shows that obesity is associated with higher block failure and complication rates in surgical regional anesthesia in the ambulatory setting. Nonetheless, the rate of successful blocks and overall satisfaction remained high in patients with increased BMI. Therefore, overweight and obese patients should not be excluded from regional anesthesia procedures in the ambulatory setting.

Major ambulatory surgery with continuous regional anesthesia and a disposable infusion pump

CONTINUOUS peripheral nerve blockade can provide prolonged postoperative analgesia. By infusing local anesthetic through a catheter, neural blockade can be achieved that lasts longer than a single-injection block. 1,2 Traditionally, this method of pain relief has required a cumbersome infusion pump and a hospital stay. Reconstructive surgery of the foot or ankle can result in severe postoperative pain that is difficult to treat. Frequently, patients having such procedures require large doses of intravenous narcotics, which make early hospital discharge difficult. By using an anesthetic method that can provide improved analgesia and obviate a prolonged hospital stay, ambulatory surgery may be facilitated. We describe two patients undergoing major ankle surgery. Both patients were discharged to their homes with a continuous Sciatic nerve block and a disposable infusion pump.

Peripheral nerve block techniques for ambulatory surgery

Peripheral nerve blocks (PNBs) have an increasingly important role in ambulatory anesthesia and have many characteristics of the ideal outpatient anesthetic: surgical anesthesia, prolonged postoperative analgesia, and facilitated discharge. Critically evaluating the potential benefits and supporting evidence is essential to appropriate technique selection. When PNBs are used for upper extremity procedures, there is consistent opioid sparing and fewer treatment-related side effects when compared with general anesthesia. This has been demonstrated in the immediate perioperative period but has not been extensively investigated after discharge. Lower extremity PNBs are particularly useful for procedures resulting in greater tissue trauma when the benefits of dense analgesia appear to be magnified, as evidenced by less hospital readmission. The majority of current studies do not support the concept that a patient will have difficulty coping with pain when their block resolves at home. Initial investigations of outpatient continuous peripheral nerve blocks demonstrate analgesic potential beyond that obtained with single-injection blocks and offer promise for extending the duration of postoperative analgesia. The encouraging results of these studies will have to be balanced with the resources needed to safely manage catheters at home. Despite supportive data for ambulatory PNBs, most studies have been either case series or relatively small prospective trials, with a narrow focus on analgesia, opioids, and immediate side effects. Ultimately, having larger prospective data with a broader focus on outcome benefits would be more persuasive for anesthesiologists to perform procedures that are still viewed by many as technically challenging.

Peripheral Nerve Blockade with Long-acting Local Anesthetics: A Survey of The Society for Ambulatory Anesthesia

Despite the growth of ambulatory anesthesia and the renewed popularity of regional techniques, there is little current information concerning outpatient regional anesthesia practices or attitudes about discharge with an insensate extremity. We present results from a survey sent to all members of the Society for Ambulatory Anesthesia (SAMBA). The survey was mailed in January 2001 to 2373 SAMBA members, along with a self-addressed stamped return envelope. After 3 mo, 1078 surveys were returned (response rate 45%). Respondents indicated that they were most likely to perform axillary (77%), interscalene (67%), and ankle blocks (68%) on ambulatory patients. They were less likely to perform lower extremity conduction blocks in ambulatory patients (femoral blocks, 40%; all other types of blocks, <23%]. Eighty-five percent of respondents discharged patients with long-acting blocks, but this was mainly limited to three types. Of the 16% who never or rarely discharged patients with long-acting blocks, the primary reasons were concern about patient injury (49%) and the inability for patients to care for themselves (28%). Only 22% of office-based anesthesiologists would perform upper extremity blocks and only 28% would perform lower extremity blocks (P < 0.001). This survey demonstrates that use of regional anesthesia in outpatients is common but restricted to a few techniques. Discharge with an insensate upper extremity is prevalent but discharge with an insensate lower extremity is not common and remains controversial. Despite the reasoning for the reported practices, randomized data are necessary to confirm the validity of these concerns.

Interscalene brachial plexus block with continuous intraarticular infusion of ropivacaine.

Providing intraarticular analgesia with a continuous infusion of local anesthetic via a disposable infusion pump has gained popularity. Despite the prevalence of this technique, data comparing this method of analgesia to conventional regional anesthesia are not available. We present a prospective study that compared a single-dose interscalene block with a single-dose interscalene block plus continuous intraarticular infusion of local anesthetic. Forty patients scheduled for shoulder arthroscopy were entered in this prospective, double-blinded study. All patients received an interscalene brachial plexus block as their primary anesthetic. Patients were randomly assigned to 1 of 2 groups: 1. interscalene block with 1.5% mepivacaine (40 mL) followed by a postoperative intraarticular infusion of 0.5% ropivacaine at 2 mL/h, or 2. interscalene block with 0.5% ropivacaine (40 mL) followed by a postoperative intraarticular infusion of 0.9% saline (placebo) at 2 mL/h. Postoperative infusions were maintained for 48 h. Visual analog scale pain scores and postoperative oxycodone consumption were measured for 48 h. Visual analog scale scores at rest and with ambulation in the Mepivacaine/Intraarticular Ropivacaine group were reduced when compared with the Ropivacaine/Saline group (rest:P = 0.003, ambulation:P = 0.006). Oxycodone consumption was also decreased (28 ± 21 mg vs 44 ± 28 mg, P = 0.046), respectively. We conclude that a brachial plexus block with 1.5% mepivacaine and a continuous intraarticular infusion of 0.5% ropivacaine at 2 mL/h provides improved analgesia for minor surgery at 24 and 48 h versus a single-injection interscalene block with 0.5% ropivacaine.