De Q. Tran

Reliability of Waveform Analysis as an Adjunct to Loss of Resistance for Thoracic Epidural Blocks.

Background The epidural space is most commonly identified with loss of resistance (LOR). Although sensitive, LOR lacks specificity, as cysts in interspinous ligaments, gaps in ligamentum flavum, paravertebral muscles, thoracic paravertebral spaces, and intermuscular planes can yield nonepidural LOR. Epidural waveform analysis (EWA) provides a simple confirmatory adjunct for LOR. When the needle is correctly positioned inside the epidural space, measurement of the pressure at its tip results in a pulsatile waveform. In this observational study, we set out to assess the sensitivity, specificity, as well as positive and negative predictive values of EWA for thoracic epidural blocks. Methods We enrolled a convenience sample of 160 patients undergoing thoracic epidural blocks for thoracic surgery, abdominal surgery, or rib fractures. The choice of patient position (sitting or lateral decubitus), approach (midline or paramedian), and LOR medium (air or normal saline) was left to the operator (attending anesthesiologist, fellow, or resident). After obtaining a satisfactory LOR, the operator injected 5 mL of normal saline through the epidural needle. A sterile tubing, connected to a pressure transducer, was attached to the needle to measure the pressure at the needle tip. A 4-mL bolus of lidocaine 2% with epinephrine 5 &mgr;g/mL was then administered and, after 10 minutes, the patient was assessed for sensory blockade to ice. Results The failure rate (incorrect identification of the epidural space with LOR) was 23.1%. Of these 37 failed epidural blocks, 27 provided no sensory anesthesia at 10 minutes. In 10 subjects, the operator was unable to thread the catheter through the needle. When compared with the ice test, the sensitivity, specificity, and positive and negative predictive values of EWA were 91.1%, 83.8%, 94.9%, and 73.8%, respectively. Conclusions Epidural waveform analysis (with pressure transduction through the needle) provides a simple adjunct to LOR for thoracic epidural blocks. Although its use was devoid of complications, further confirmatory studies are required before its routine implementation in clinical practice.

A Randomized Comparison Between Ultrasound- and Fluoroscopy-guided Sacral Lateral Branch Blocks

Background and Objectives This randomized trial compared ultrasound (US)- and fluoroscopy-guided sacral lateral branch (SLB) blocks. We hypothesized that US would require a shorter performance time. Methods Forty patients who required unilateral sacral lateral branch blocks for chronic low back pain were randomized to US or fluoroscopy guidance. Before the performance of the assigned block, an investigator who was not involved in patient care carried out baseline analgesic testing. With US, the dorsal sacroiliac ligament, the sacroiliac joint, and the interosseous ligament were probed with a 22-gauge block needle. The patient was asked to rate the level of discomfort using an 11-point numerical rating scale. After the analgesic test, attending anesthesiologists or supervised trainees carried out the SLB blocks. The local anesthetic agent (lidocaine 2%) was identical in all subjects. In the US group, local anesthetic (1.5 mL) was first injected on the lateral crest at the mid-point between S2 and S3. Subsequently, 2 more injections of 0.5 mL were carried out on the lateral crest, immediately cephalad to S2 and at the S1 level. In the fluoroscopy group, SLB blocks were performed according to a previously described 17-injection technique, which involves 9 skin entry sites and the targeting of the L5 posterior root and S1-S3 sacral lateral branches. A 0.4-mL volume of local anesthetic was deposited at each target point. The performance time, number of needle passes, and the incidence of vascular breach were recorded during the performance of the block. Twenty minutes after the end of local anesthetic injection, the same investigator who performed preblock analgesic testing carried out postblock testing in an identical manner. Results Compared with fluoroscopy, the US technique was associated with a shorter performance time (267.5 ± 99.3 vs 628.7 ± 120.3 seconds; P < 0.001), fewer needle passes and a lower incidence of vascular breach (0 vs 10 occurrences; P = 0.001). However, the block effect (ie, the proportional decrease in numerical rating scale between preblock and postblock analgesic testing) was similar in both groups. Furthermore, no statistical differences were found in the proportions of patients achieving complete analgesia at each test site. The level of experience (ie, expert vs novice operator) significantly affected performance time with US but not with fluoroscopy. No procedural complications were recorded with either imaging modality during the 30-day follow-up period. Conclusions Compared with their fluoroscopic counterparts, US-guided SLB blocks require a shorter performance time as well as fewer needle passes and carry a lower risk of vascular breach.

A Randomized Comparison Between Single- and Triple-Injection Subparaneural Popliteal Sciatic Nerve Block.

Background and Objectives This prospective randomized trial compared ultrasound-guided single-injection (SI) and triple-injection (TI) subparaneural popliteal sciatic nerve block. We hypothesized that multiple injections are not required when local anesthetic (LA) is deposited under the paraneurium because the latter entraps LA molecules, ensuring circumferential spread around the nerve. Therefore, in addition to comparable success rates, we also expected similar total anesthesia-related times (sum of performance and onset times) and designed this study as an equivalency trial. Methods Ultrasound-guided subparaneural posterior popliteal sciatic nerve block was carried out in 100 patients. In the SI group, LA was deposited at a single location between the tibial and peroneal nerves. In the TI group, LA was injected between the tibial and peroneal divisions, medial to the tibial nerve, and lateral to the common peroneal nerve. The total LA volume (15 mL) and mixture (lidocaine 1%–bupivacaine 0.25%–epinephrine 5 &mgr;g/mL) were identical in all subjects. The performance time, number of needle passes, and adverse events (paresthesia, neural edema) were recorded by the (nonblinded) investigator supervising the block. A blinded observer evaluated the success rate (sensorimotor composite score ≥6/8 points at 30 minutes) as well as the onset time and contacted patients 7 days after the surgery to inquire about persistent numbness or motor deficit. Results Both techniques provided comparable success rates (92%) and total anesthesia-related times (17.1–19.7 minutes). Expectedly, the SI group required fewer needle passes (1 vs 3; P < 0.001) and a shorter needling time (3.0 ± 2.3 minutes vs 4.0 ± 2.3 minutes; P = 0.025). The TI group displayed a shorter onset time (12.5 ± 7.9 minutes vs 15.8 ± 7.9 minutes; P = 0.027). The performance time, procedural discomfort, and incidence of paresthesia (14%–20%) were similar between the 2 groups. Sonographic neural swelling was detected in 2 subjects in the SI group. In both cases, the needle was carefully withdrawn and the injection was completed uneventfully. Follow-up of the 100 subjects 1 week after surgery revealed no residual numbness or motor deficit. Conclusions Ultrasound-guided SI and TI subparaneural popliteal sciatic nerve blocks result in comparable success rates and total anesthesia-related times. Expectedly, the SI technique requires fewer needle passes.

A systematic review of DURAL puncture epidural analgesia for labor

STUDY OBJECTIVE This systematic review aimed to summarize the evidence derived from randomized controlled trials (RCTs) comparing dural puncture epidural analgesia (DPEA) and conventional lumbar epidural analgesia (LEA) for women undergoing labor. INTERVENTIONS The MEDLINE and EMBASE databases were searched from inception to July 2018 in order to find RCTs published in the English language, which investigated DPEA in laboring women. MAIN RESULTS Six RCTs were included in the final analysis. Their collective results remain ambiguous. Dural puncture with small (i.e., 26- or 27-gauge) spinal needles seems to confer either minimal benefits or improved analgesic quality and lower pain scores in the first 10 min. Dural puncture with 25-gauge spinal needles has been reported to provide higher success rate than conventional LEA in one trial; however two other studies could only agree on the fact that DPEA results in improved sacral blockade and fewer unilateral blocks compared to LEA. CONCLUSIONS The current evidence regarding DPEA for labor analgesia remains ambiguous. Future research should investigate the optimal (spinal) needle size for dural puncture as well as factors governing transmeningeal flux of local anesthetics and opioids in the presence of a dural hole.

Perioperative insulin therapy

Abstract Surgical patients commonly develop hyperglycemia secondary to the neuroendocrine stress response. Insulin treatment of hyperglycemia is required to overcome the perioperative catabolic state and acute insulin resistance. Besides its metabolic actions on glucose metabolism, insulin also displays nonmetabolic physiological effects. Preoperative glycemic assessment, maintenance of normoglycemia, and avoidance of glucose variability are paramount to optimize surgical outcomes. This review discusses the basic physiology and effects of insulin as well as practical issues pertaining to its management during the perioperative period.

Reply to Dr Price

will almost certainly result in a greater degree of arm and hand paralysis than seen with ISB performed at the level of C5– C6. In addition, they must also be compared with CSANB to see whether they have lower 24-hour pain scores that those reported following ISB. The technique proposed by Tran et al, combining suprascapular nerve with infraclavicular block, must also be compared with CSANB with regard to rebound pain, but as there are 2 separate injections, it may have a more favorable resolution profile. On the downside, it will also result in a numb arm. Because most shoulder surgery in New Zealand is performed using both a nerve block and general anesthesia, the fact that CSANB cannot be used with sedation alone is seldom an issue. However, where it is preferable to avoid both general anesthesia and prolonged PhNB, I use ISB and CSANB in combination. The ISB is performed with 5 mL of lignocaine. The low volume minimizes the degree of PhNB, and should it be poorly tolerated, it does wear off quickly. A ropivacaine CSANB extends analgesia beyond ISB resolution. One advantage of this combination is that the lignocaine ISB is still active in the immediate postoperative period, when anterior pain not covered by CSANB would be at its most intense.

Diaphragm-sparing nerve blocks for shoulder surgery an alternative approach reply

nerve via a Pecs 1 block. The suprascapular and axillary nerve blocks are done via the classic methods described by Meier et al and Price, respectively. Blockade of the lateral pectoral nerve is important to provide analgesia to the anterior shoulder and is best blocked by the Pecs I approach described by Blanco. We have also used this block as a rescue modality for anterior shoulder pain. All 4 of these blocks can also be conducted via ultrasound, and the safety profile for each has minimal risks compared with the classic interscalene approach to the brachial plexus and a combined suprascapular-infraclavicular nerve block. Ultimately, studies need to be conducted comparing the 4-block approach to combined suprascapular and infraclavicular blocks in regard to safety and analgesic effect.