Timothy E. Morey

Continuous Popliteal Sciatic Nerve Block for Postoperative Pain Control at Home A Randomized, Double-Blinded, Placebo-Controlled Study

Background This randomized, double-blinded, placebo-controlled study investigated the efficacy of patient-controlled regional analgesia using a sciatic perineural catheter in the popliteal fossa and a portable infusion pump for outpatients having moderately painful, lower extremity orthopedic surgery. Methods Preoperatively, patients (n = 30) received a sciatic nerve block and perineural catheter in the popliteal fossa. Postoperatively, patients were discharged with both oral opioids and a portable infusion pump delivering study solution (0.2% ropivacaine or 0.9% saline) via the catheter for 3 days. Investigators and patients were blinded to random group assignment. Daily end-points included pain scores, opioid use and side effects, sleep quality, and symptoms of catheter- or local anesthetic-related complications. Results Ropivacaine (n = 15) infusion significantly reduced pain compared with saline (n = 15) infusion (P < 0.001). For example, the average pain at rest (scale: 0–10) on postoperative day 1 (median, 25th–75th percentile) was 4.0 (3.5–5.5) for the saline group, versus 0.0 (0.0–0.0) for the ropivacaine group (P < 0.001). Oral opioid use and related side effects were significantly decreased in the ropivacaine group. For example, on postoperative day 1, median tablet consumption was 8.0 (5.0–10.0) and 0.0 (0.0–0.0) for the saline and ropivacaine groups, respectively (P < 0.001). Sleep disturbance scores were more than 10-fold greater for saline administration than for ropivacaine infusion (P < 0.001). Overall satisfaction was significantly greater in the ropivacaine group. Other than two inadvertent catheter dislodgements, no catheter- or local anesthetic-related complications occurred. Conclusions After moderately painful orthopedic surgery of the lower extremity, ropivacaine infusion using a portable mechanical pump and a popliteal sciatic perineural catheter at home decreased pain, opioid use and related side effects, sleep disturbances, and improved overall satisfaction.

Continuous infraclavicular brachial plexus block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study.

Background This randomized, double-blinded, placebo-controlled study investigated the efficacy of patient-controlled regional analgesia using an infraclavicular brachial plexus perineural catheter and a portable infusion pump for outpatients undergoing moderately painful, upper extremity orthopedic surgery. Methods Preoperatively, patients (n = 30) received an infraclavicular nerve block and perineural catheter. Postoperatively, patients were discharged home with oral narcotics and a portable infusion pump delivering study solution (0.2% ropivacaine or 0.9% saline) via the catheter for 3 days. Investigators and patients were blinded to random group assignment. Daily end points included pain scores at rest and with limb movement, narcotic use and side effects, sleep quality, patient satisfaction, and symptoms of catheter- or local anesthetic-related complications. Results Ropivacaine (n = 15) infusion significantly reduced pain compared with saline (n = 15) infusion (P < 0.001). For example, the average pain with movement (scale, 0–10) on postoperative day 1 was 6.1 ± 2.3 for the saline group versus 2.5 ± 1.6 for the ropivacaine group (P < 0.001). Oral narcotic use and related side effects were significantly decreased in the ropivacaine group. For example, on postoperative day 1, mean tablet consumption was 5.5 ± 2.4 and 1.7 ± 1.6 for the saline and ropivacaine groups, respectively (P < 0.001). Sleep disturbance scores were 10-fold greater for saline administration than for ropivacaine infusion (P < 0.001). Overall satisfaction was significantly greater in the ropivacaine group. No catheter- or local anesthetic-related complications occurred. Conclusion After moderately painful orthopedic surgery of the upper extremity, ropivacaine infusion using a portable, mechanical pump and an infraclavicular brachial plexus perineural catheter at home decreased pain, sleep disturbances, narcotic use and related side effects, and improved overall satisfaction.

Infraclavicular perineural local anesthetic infusion: a comparison of three dosing regimens for postoperative analgesia.

BackgroundIn this randomized, double-blind study, the authors investigated the efficacy of continuous and patient-controlled ropivacaine infusions via an infraclavicular perineural catheter in ambulatory patients undergoing moderately painful orthopedic surgery at or distal to the elbow. MethodsPreoperatively, patients (n = 30) received an infraclavicular perineural catheter and nerve block. Postoperatively, patients were discharged home with both oral analgesics and a portable infusion pump delivering 0.2% ropivacaine (500-ml reservoir) in one of three dosing regimens: the basal group (12 ml/h basal, 0.05-ml patient-controlled bolus dose), the basal–bolus group (8 ml/h basal, 4 ml bolus), or the bolus group (0.3 ml/h basal, 9.9 ml bolus). Investigators and patients were blinded to random group assignment. ResultsThe basal group (n = 10) required more oral analgesics than the basal–bolus group (P = 0.002) and had a shorter median infusion duration than the other two groups (P < 0.001 for both). The bolus group had the longest median infusion duration (P < 0.001 for both) but experienced an increase in breakthrough pain incidence (P = 0.004) and intensity (P = 0.04 vs. basal–bolus group) as well as sleep disturbances (P < 0.001 for both) compared with the other groups. Overall satisfaction was greatest in the basal–bolus group (9.7 ± 0.5 vs. 7.9 ± 1.7 and 8.1 ± 1.5; P < 0.05 for both). ConclusionsAfter moderately painful orthopedic surgery at or distal to the elbow, 0.2% ropivacaine delivered as a continuous infusion combined with patient-controlled bolus doses via an infraclavicular perineural catheter optimizes analgesia while minimizing oral analgesic use compared with basal- or bolus-only dosing regimens.

Interscalene perineural ropivacaine infusion:a comparison of two dosing regimens for postoperative analgesia.

Background and Objectives: A continuous interscalene nerve block with a perineural infusion of ropivacaine 0.2% at 8 mL/h has been shown to provide potent analgesia following moderately painful shoulder surgery. However, this high basal rate limits infusion duration for ambulatory patients who must carry the local anesthetic reservoir. We undertook this investigation to determine if the basal rate of an interscalene perineural ropivacaine infusion could be decreased by 50% with a concurrent 200% increase in patient-controlled bolus dose without compromising infusion benefits in ambulatory patients undergoing moderately painful orthopedic shoulder surgery. Methods: Preoperatively, patients (n = 24) received an interscalene perineural catheter and nerve block. Intraoperatively, patients received a standardized general anesthetic. Postoperatively, patients were discharged home with a portable infusion pump delivering ropivacaine 0.2% (500 mL reservoir) with a basal rate of 8 mL/h and a 2 mL patient-controlled bolus available each hour (“8/2” group, n = 12) or a 4 mL/h basal rate and 6 mL bolus dose (“4/6” group, n = 12), delivered in a randomized, double-blinded manner. Results: Patients in the 4/6 group had higher baseline pain scores only on postoperative day (POD) 2 (P = .011). However, these patients also experienced an increase in breakthrough pain incidence (5.8 boluses/d v 3.2, P = .035) and intensity (“worst” pain = 8/10 v 4/10, P < .05), sleep disturbances (2.0 v 0.0, P < .001), and a decrease in analgesia satisfaction (8 v 10, P = .003). Patients in the 8/2 group exhausted their local anesthetic reservoirs after a median of 61 hours, while the 4/6 group had a median of 131 mL remaining at infusion discontinuation after a median of 75 hours (P < .001). Conclusions: Following moderately painful ambulatory shoulder surgery, decreasing an interscalene perineural ropivacaine 0.2% basal rate from 8 to 4 mL/h provides similar baseline analgesia and lengthens infusion duration, but compromises other infusion benefits.

Cricoid Pressure Results in Compression of the Postcricoid Hypopharynx: The Esophageal Position Is Irrelevant

BACKGROUND: Sellick described cricoid pressure (CP) as pinching the esophagus between the cricoid ring and the cervical spine. A recent report noted that with the application of CP, the esophagus moved laterally more than 90% of the time, questioning the efficacy of this maneuver. We designed this study to accurately define the anatomy of the Sellick maneuver and to investigate its efficacy. METHODS: Twenty-four nonsedated adult volunteers underwent neck magnetic resonance imaging with and without CP. Measurements were made of the postcricoid hypopharynx, airway compression, and lateral displacement of the cricoid ring during the application of CP. The relevant anatomy was reviewed. RESULTS: The hypopharynx, not the esophagus, is what lies behind the cricoid ring and is compressed by CP. The distal hypopharynx, the portion of the alimentary canal at the cricoid level, was fixed with respect to the cricoid ring and not mobile. With CP, the mean anterioposterior diameter of the hypopharynx was reduced by 35% and the lumen likely obliterated, and this compression was maintained even when the cricoid ring was lateral to the vertebral body. CONCLUSIONS: The location and movement of the esophagus is irrelevant to the efficiency of the Sellick’s maneuver (CP) in regard to prevention of gastric regurgitation into the pharynx. The hypopharynx and cricoid ring move together as an anatomic unit. This relationship is essential to the efficacy and reliability of Sellick’s maneuver. The magnetic resonance images show that compression of the alimentary tract occurs with midline and lateral displacement of the cricoid cartilage relative to the underlying vertebral body.

Cross-sectional area of the right and left internal jugular veins.

OBJECTIVE To compare the cross-sectional area (CSA) of the right internal jugular vein (RIJV) with the left internal jugular vein (LIJV) using two-dimensional ultrasound and to measure the response to the Valsalva maneuver in both the supine and Trendelenburg positions. DESIGN Prospective and randomized. SETTING University-affiliated hospital. PARTICIPANTS Fifty healthy adult volunteers. INTERVENTIONS The CSA of both the RIJV and LIJV was measured with a 5-MHz, two-dimensional surface transducer before and during a 10-second Valsalva maneuver with the subjects in the supine position, and then with the subjects in a 10 degree Trendelenburg tilt. MEASUREMENTS AND MAIN RESULTS After the baseline measurements were performed, the subjects were divided into two groups based on the CSA of the RIJV and LIJV. Group 1 had an LIJV CSA equal to or greater than that of the RIJV (n = 10) and group 2 had an LIJV CSA less than that of the RIJV (n = 40). Of the latter 40 patients, 17 (34%) had an LIJV CSA less than 50% of that of the RIJV. In both groups, the CSA of both veins increased significantly with the Valsalva maneuver, Trendelenburg tilt, and both maneuvers combined. CONCLUSION The findings suggest that in one third of adults (34%), the LIJV is significantly smaller compared with the RIJV and, combined with operator inexperience, may influence the success rate and risk for complications. Thus, the use of ultrasound and maneuvers that increase CSA is suggested during LIJV cannulation.

Falls associated with lower-extremity-nerve blocks: a pilot investigation of mechanisms.

Objective: Documented falls after lower-extremity-nerve blocks are rare. We believe this paucity of documented falls is the result of underreporting and the lack of serious complications resulting from these falls. In addition, the mechanism(s) for falls after lower-extremity-nerve blocks has not been elucidated. Case Reports: These reports highlight the mechanism of fall in a patient with a femoral-nerve block (FNB) and in a patient with a femoral-nerve and sciatic-nerve block (FNB/SNB). In addition, we report our findings when volunteers underwent FNB, sciatic-nerve block (SNB) and FNB/SNB and were studied in a gait-analysis laboratory. Conclusions: Lower-extremity-nerve blocks result in decreased leg stiffness and lateral instability, which may lead to difficulty with pivoting maneuvers.

Popliteal sciatic perineural local anesthetic infusion: A comparison of three dosing regimens for postoperative analgesia

Background:This randomized, double-blind study investigated the efficacy of continuous and patient-controlled ropivacaine infusion via a popliteal sciatic perineural catheter in ambulatory patients undergoing moderately painful orthopedic surgery of the foot or ankle. Methods:Preoperatively, patients (n = 30) received a posterior popliteal sciatic perineural catheter and nerve block. Postoperatively, patients were discharged home with a portable infusion pump delivering 0.2% ropivacaine (500 ml) in one of three dosing regimens: the basal group (12-ml/h basal rate, 0.05-ml patient-controlled bolus dose), the basal–bolus group (8-ml/h basal rate, 4-ml bolus dose), or the bolus group (0.3-ml/h basal rate, 9.9-ml bolus dose). Results:The bolus group experienced an increase in baseline pain, breakthrough pain incidence and intensity, and sleep disturbances compared with the other two groups (P < 0.05 for all comparisons). Compared with the basal–bolus group, the basal group experienced an increase in these outcome measures only after local anesthetic reservoir exhaustion, which occurred earlier than in the other two groups (P < 0.05 for all comparisons). Satisfaction scores did not differ among the three groups. Conclusions:This study demonstrates that when providing analgesia with 0.2% ropivacaine via a popliteal sciatic perineural catheter after moderately painful surgery of the foot or ankle, a continuous infusion is required to optimize infusion benefits. Furthermore, adding patient-controlled bolus doses allows for a lower continuous basal rate and decreased local anesthetic consumption and thereby increases the duration of infusion benefits when in an ambulatory environment with a limited local anesthetic reservoir.

Portable infusion pumps used for continuous regional analgesia: delivery rate accuracy and consistency☆

Background and Objectives: Multiple benefits of postoperative perineural local anesthetic infusion have been shown including potent analgesia, decreased opioid requirements, and improved rehabilitation. Consequently, portable infusion pumps have been used with increasing frequency to provide perineural infusion for medically unsupervised ambulatory patients. We believe that the infusion rate accuracy and reliability of these pumps infusing potentially toxic doses of medication should be investigated independently. Therefore, we studied the flow-rate accuracy and consistency of various portable infusion pumps that have not been examined previously. Methods: Using a computer/mass balance combination to record infusion rates, 6 pumps (3 electronic and 3 nonelectronic) were tested. Several factors that may influence pump performance were varied: temperature (ambient/skin), battery (replacement/addition), and catheter exchange (wound/perineural). Results: Infusion rate accuracy differed significantly among the pumps, exhibiting flow rates within ±15% of their expected rate for 55% to 99% of their infusion duration. Furthermore, the profiles (infusion rate over time) of the various pumps differed significantly depending on the pump power source. Although elastomeric pump infusion rate increased with an increase in temperature, battery life was a limiting factor for one of the electronic pumps. Substituting wound catheters with commonly used perineural catheters did not significantly alter infusion profile. Conclusions: Factors such as infusion rate accuracy and consistency, infusion profile, temperature sensitivity, and battery life affect the dose of medication administered by various portable pumps used for continuous regional analgesia. Health care providers should take these factors into consideration when choosing and using a portable infusion pump for local anesthetic administration.

The delivery rate accuracy of portable infusion pumps used for continuous regional analgesia.

Portable pumps used for local anesthetic infusion during continuous regional analgesia are gaining acceptance. These pumps are often used for ambulatory patients who are medically unsupervised throughout most of the infusion. However, the performance of these pumps, which infuse potentially toxic medication, has not been independently investigated. We investigated the flow rate accuracy, consistency, and profiles of various portable pumps often used for local anesthetic infusion during continuous regional analgesia. By using a computer/scale combination within a laboratory to record infusion rates, 6 pumps were tested with their flow regulators at expected (30°–32°C) and increased (34°–36°C) temperatures. Infusion rate accuracy differed significantly among the pumps, exhibiting flow rates within ±15% of their expected rate for 18%–100% of their infusion duration. An increase in temperature also affected pumps to differing degrees, with infusion rates increasing from 0% to 25% for each model tested. These results suggest that factors such as flow rate accuracy and consistency, infusion profile, and temperature sensitivity should be considered when choosing and using a portable infusion pump for local anesthetic administration.