[show abstract][hide abstract] ABSTRACT: It remains unclear whether local anesthetic concentration or total drug dose is the primary determinant of continuous peripheral nerve block effects. The only previous investigation, involving continuous popliteal-sciatic nerve blocks, specifically addressing this issue reported that insensate limbs were far more common with higher volumes of relatively dilute ropivacaine compared with lower volumes of relatively concentrated ropivacaine. However, it remains unknown if this relationship is specific to the sciatic nerve in the popliteal fossa or whether it varies depending on anatomic location. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates, but at an equal total basal dose, produces comparable effects when used in a continuous infraclavicular brachial plexus block.
Preoperatively, an infraclavicular catheter was inserted using the coracoid approach in patients undergoing moderately painful orthopedic surgery distal to the elbow. Patients were randomly assigned to receive a postoperative perineural ropivacaine infusion of either 0.2% (basal 8 mL/h, bolus 4 mL) or 0.4% (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Both groups, therefore, received 16 mg of ropivacaine each hour with a possible addition of 8 mg every 30 min via a patient-controlled bolus dose. Our primary end point was the incidence of an insensate limb during the 24-h period beginning the morning after surgery. Secondary end points included analgesia and patient satisfaction.
Patients given 0.4% ropivacaine (n = 27) experienced an insensate limb, a mean (sd) of 1.8 (1.6) times, compared with 0.6 (0.9) times for subjects receiving 0.2% ropivacaine (n = 23; estimated difference = 1.2 episodes, 95% confidence interval, 0.5-1.9 episodes; P = 0.001). Satisfaction with postoperative analgesia (scale 0-10, 10 = highest) was scored a median (25th-75th percentiles) of 10.0 (8.0-10.0) in Group 0.2% and 7.0 (5.3-8.9) in Group 0.4% (P = 0.018). Analgesia was similar in each group.
For continuous infraclavicular nerve blocks, local anesthetic concentration and volume influence perineural infusion effects in addition to the total mass of local anesthetic administered. Insensate limbs were far more common with smaller volumes of relatively concentrated ropivacaine. This is the opposite of the relationship previously reported for continuous popliteal-sciatic nerve blocks. The interaction between local anesthetic concentration and volume is thus complex and varies among catheter locations.
Anesthesia and analgesia 02/2009; 108(1):345-50. · 3.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Brachial plexus blockade is the cornerstone of the peripheral nerve regional anesthesia practice of most anesthesiologists. As part of the American Society of Regional Anesthesia and Pain Medicine's commitment to providing intensive evidence-based education related to regional anesthesia and analgesia, this article is a complete update of our 2002 comprehensive review of upper extremity anesthesia. The text of the review focuses on (1) pertinent anatomy, (2) approaches to the brachial plexus and techniques that optimize block quality, (4) local anesthetic and adjuvant pharmacology, (5) complications, (6) perioperative issues, and (6) challenges for future research.
Regional anesthesia and pain medicine 01/2009; 34(2):134-70. · 4.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: It remains unknown whether local anesthetic concentration, or simply total drug dose, is the primary determinant of continuous peripheral nerve block effects. We therefore tested the null hypothesis that providing different concentrations and rates of ropivacaine, but at equal total doses, produces comparable effects when used in a continuous sciatic nerve block in the popliteal fossa.
Preoperatively, a perineural catheter was inserted adjacent to the sciatic nerve using a posterior popliteal approach in patients undergoing moderately painful orthopedic surgery at or distal to the ankle. Postoperatively, patients were randomly assigned to receive a perineural ropivacaine infusion of either 0.2% (basal 8 mL/h, bolus 4 mL) or 0.4% (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Therefore, both groups received 16 mg of ropivacaine each hour with a possible addition of 8 mg every 30 min via a patient-controlled bolus dose. The primary end point was the incidence of an insensate limb, considered undesirable, during the 24-h period beginning the morning after surgery. Secondary end points included analgesia and patient satisfaction.
Patients given 0.2% ropivacaine (n = 25) experienced an insensate limb with a mean (sd) of 1.8 (1.8) times, compared with 0.6 (1.1) times for subjects receiving 0.4% ropivacaine (n = 25; estimated difference = 1.2 episodes, 95% confidence interval, 0.3-2.0 episodes; P = 0.009). In contrast, analgesia and satisfaction were similar in each group.
For continuous popliteal-sciatic nerve blocks, local anesthetic concentration and volume influence block characteristics. Insensate limbs were far more common with larger volumes of relatively dilute ropivacaine. During continuous sciatic nerve block in the popliteal fossa, a relatively concentrated solution in smaller volume thus appears preferable.
Anesthesia and analgesia 08/2008; 107(2):701-7. · 3.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: The management of patients with coronary artery stents during the perioperative period is one of the most important patient safety issues clinicians confront. Perioperative stent thrombosis is a life-threatening complication for patients with either bare-metal or drug-eluting stents. Noncardiac surgery appears to increase the risk of stent thrombosis, myocardial infarction, and death, particularly when patients undergo surgery early after stent implantation. The incidence of complications is further increased when dual-antiplatelet therapy is discontinued preoperatively. It is generally agreed that aspirin must be continued throughout the perioperative period, except in circumstances when the risk of bleeding significantly outweighs the benefit of continued anticoagulation, such as procedures performed in a closed space. We present considerations for regional anesthesia, as well as postoperative recommendations as the occurrence of perioperative stent thrombosis appears to be greatest during this period. Immediate percutaneous coronary intervention is the definitive treatment for perioperative stent thrombosis, and 24-h access to an interventional cardiology suite should be readily available. Algorithms for perioperative management of patients with bare-metal and drug-eluting stents are proposed.
Anesthesia and analgesia 08/2008; 107(2):570-90. · 3.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Local anesthetic-induced cardiotoxicity remains a complication of regional anesthesia, with the potential to result in cardiac arrest refractory to resuscitation. Successful resuscitation using Intralipid (Baxter Pharmaceuticals by Fresenius Kabi, Uppsala, Sweden), has been reported in 2 patients with bupivacaine-induced cardiac arrest.
We report another case for which Intralipid was used as part of a successful resuscitation in a patient with local anesthetic-induced cardiotoxicity.
Early treatment with Intralipid may help prevent cardiac arrest and speed successful resuscitation efforts.
Regional Anesthesia and Pain Medicine 01/2008; 33(2):178-80. · 3.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: It is currently unknown if the primary determinant of continuous peripheral nerve block effects is simply total drug dose, or whether local anesthetic concentration and/or volume have an influence. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates--but at an equal total basal dose--produces similar effects when used in a continuous interscalene nerve block.
Preoperatively, an anterolateral interscalene perineural catheter was inserted using the anterolateral approach in patients undergoing moderately painful shoulder surgery. Subjects were randomly assigned to receive a postoperative perineural infusion of either 0.2% ropivacaine (basal 8 mL/h, bolus 4 mL) or 0.4% ropivacaine (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Our primary endpoint was the incidence of an insensate hand/finger during the 24 hours beginning the morning following surgery.
The incidence of an insensate hand/finger did not differ between the treatment groups (n = 50) to a statistically significant degree (0.2% ropivacaine, mean [SD] of 0.8 [1.3] times; 0.4% ropivacaine, mean 0.3 [0.6] times; estimated difference = 0.5 episodes, 95% confidence interval, -0.1 to 1.1 episodes; P = .080). However, this is statistically inconclusive given the confidence interval. In contrast, pain (P = .020) and dissatisfaction (P = .011) were greater in patients given 0.4% ropivacaine.
For continuous interscalene nerve blocks, given the statistically inconclusive primary endpoint results and design limitations of the current study, further research on this topic is warranted. In contrast, providing a lower concentration of local anesthetic at a higher basal rate provided superior analgesia.
Regional anesthesia and pain medicine 01/2008; 33(6):518-25. · 4.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: Several variations on the technique for infraclavicular brachial plexus block have been described. The coracoid infraclavicular technique has become popular because of easily identified landmarks, reliable distribution of blockade, and low risk of respiratory complications such as pneumothorax. We report a case of pneumothorax in a patient after a coracoid infraclavicular brachial plexus block. Subtleties in landmark identification and measurement may affect the risk of pneumothorax.
Anesthesia and analgesia 08/2007; 105(1):275-7. · 3.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: The use of epidural opioid can no longer be considered a novel postoperative analgesic, whether used as a one-time bolus or given via an epidural infusion with or without local anesthetic. In this role, epidural opioid is well accepted and efficacious. However, epidurals and other current strategies for treating acute postoperative pain are all limited by side effects and complications. Epidural infusions can provide excellent postoperative analgesia but can also lead to problems and complications related to catheter placement, such as the potential for epidural hematoma with anticoagulation, technical issues with the infusion pumps, and the time and labor necessary to place, adjust, and manage catheters and infusions. Extended-release epidural morphine (EREM, DepoDur®; Endo Pharmaceuticals, Chadds Ford, PA) has been studied and increasingly utilized as a method to improve postoperative analgesia of epidural dosing without the use of infusions. Via a delivery system using liposome encapsulation, EREM provides novel analgesic benefits but also contributes a new set of concerns to the field of pain management: unique onset and duration of opioid adverse effects. These issues have generated controversy in clinical anesthesia. In this review, we provide an overview of the published basic science, background research, and current clinical studies, as well as recent applications and experience with EREM.
Techniques in Regional Anesthesia [amp ] Pain Management 01/2007; 11(1):9-18.
[show abstract][hide abstract] ABSTRACT: Though new local anesthetics (LA), effective test-dosing, and new regional anesthetic techniques may have improved the safety of regional anesthesia, the optimal management plan for LA-induced cardiac toxicity remains uncertain. Accordingly, we evaluated current approaches to LA cardiotoxicity among academic anesthesiology departments in the United States. A 19-question survey regarding regional anesthesia practices and approaches to LA cardiac toxicity was sent to the 135 academic anesthesiology departments listed by the Society of Academic Anesthesiology Chairs-Association of Anesthesiology Program Directors. Ninety-one anonymously completed questionnaires were returned, at a response rate of 67%. The respondents were categorized into groups according to the number of peripheral nerve blocks (PNBs) performed each month: >70 PNBs (38%), 51-70 PNBs (13%), 31-50 PNBs (20%), 11-30 PNBs (23%), and <10 PNBs (6%). Anesthesia practices administering >70 PNBs were 1.7-times more likely to use ropivacaine (NS), 3.9-times more likely to consider lipid emulsion infusions for resuscitation (P = 0.008), and equally as likely to have an established plan for use of invasive mechanical cardiopulmonary support in the event of LA cardiotoxicity (NS) than low-PNB volume centers. We conclude that there are differences in the management and preparedness for treatment of LA toxicity among institutions, but the safety implications of these differences are undetermined.
Anesthesia and analgesia 11/2006; 103(5):1322-6. · 3.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Despite the tremendous growth of peripheral nerve blocks, no standard format exists to document their performance. Our objective was to create a peripheral nerve block form based on key elements of literature evidence and on our own group consensus.
We describe the process and results of our multi-institutional effort to construct a standardized peripheral nerve block procedure form.
A form was developed to help meet the medical, legal, and billing requirements of documentation consistent with the performance of peripheral nerve block.
Regional Anesthesia and Pain Medicine 01/2005; 30(1):67-71. · 3.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: The study was performed to determine whether epidural fentanyl produced segmental sensory changes to electrical stimulation at different frequencies. Eight healthy volunteers received fentanyl 1 microgram/kg both intravenously and epidurally in a randomized, double-blind, cross-over fashion. Perception thresholds and amount of current required to elicit a predetermined level of moderate pain (Cmp) at 5,250, and 2000 Hz stimulation were measured at ipsilateral dermatomes C2 and L2 at 0, 5, 15, 30, 45, and 60 min after injection. Perceptions to 5,250, and 2000 Hz stimulation were unaffected by either intravenous or epidural fentanyl (P > 0.08). Intravenous fentanyl increased Cmp at both 5 and 250 Hz at both dermatomes (P < 0.004) and thus did not produce segmental analgesia. In contrast, epidural fentanyl increased Cmp only at the L2 dermatome and only at 5 Hz (P = 0.005). We conclude that an epidural bolus of fentanyl results in segmental spinal analgesia to transcutaneous electrical stimulation only at specific frequencies. Furthermore, pain produced by stimulation at 5 Hz may have a different pharmacology than pain produced by 250 Hz stimulation.
[show abstract][hide abstract] ABSTRACT: Premedication with oral clonidine may improve the quality and duration of lidocaine spinal anesthesia, but this effect has not been examined in a quantitative fashion.
Eight volunteers received 50 mg lidocaine (1.5% dextrose free) both with and without 0.2 mg oral clonidine 1.5 h before spinal anesthesia in a randomized, double-blind, placebo-controlled, crossover fashion. Sensory block was assessed by pinprick, transcutaneous electric stimulation equivalent to surgical incision, and duration of tolerance to pneumatic thigh tourniquet. Motor block at the quadriceps and gastrocnemius muscles was assessed by isometric force dynamometry. Episodes of bradycardia, hypotension, and sedation were recorded.
Regression of pinprick was unchanged with clonidine. However, duration of tolerance to electric stimulation was increased at the knee (28 +/- 24 min) and ankle (31 +/- 28 min) with clonidine (P < 0.05). The duration of tolerance to tourniquet-induced pain was increased with clonidine (14 +/- 12 min; P < 0.05). The duration of motor block was increased at the quadriceps (20 +/- 13 min) and gastrocnemius (33 +/- 24 min) muscle groups with clonidine (P < 0.05). Although clonidine decreased systolic blood pressure (13 +/- 4 mmHg, P < 0.003) and heart rate (13 +/- 5 beats/min; P = 0.02), no subjects had hypotension or bradycardia. The incidence of sedation was greater with clonidine than with plain lidocaine (50% vs. 0%, P < 0.04).
Premedication with oral clonidine prolonged sensory and motor block from lidocaine spinal anesthesia. The exact mechanism whereby oral clonidine prolongs spinal anesthesia remains to be determined.
[show abstract][hide abstract] ABSTRACT: A continuous spinal anesthetic was planned and conducted for a medically compromised and demented 80-year-old man presenting for repair of an intratrochanteric hip fracture.
A peripheral nerve stimulator was successfully employed to monitor the height and to help time the redosing of the continuous spinal anesthetic.
The use of a peripheral nerve stimulator allowed careful titration of our continuous spinal anesthetic to provide dense analgesia at the surgical site for 1 hour 5 minutes, using a total spinal dose of 27 mg lidocaine and 7.5 micrograms spinal fentanyl.
A standard peripheral nerve stimulator is an effective monitor to help optimize management of continuous spinal anesthesia.