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Anahi Perlas

Publications and source records attributed to Anahi Perlas.

9 recordsLinked to original sources
PubMed2007

Ultrasound-guided peripheral nerve blockade.

Peripheral nerve blockade (PNB) for orthopedic surgery is usually performed without visual guidance, relying mainly on surface anatomic landmarks and electrical stimulation to localize nerves. Moreover, multiple trial and error attempts to place a needle can frustrate the operator, cause unwarranted pain to the patient, and waste valuable time in the operating room. Inaccurate needle placement and spread of local anesthetic account for most PNB failures, whereas "trial and error" needle manipulations for nerve localization can cause complications. The recent application of ultrasound (US) to PNB affords real-time imaging of the target nerve, needle, and surrounding vasculature, such that needle proximity to the nerve is ensured and vascular puncture avoided. This article reviews the advantages, principles, and techniques of US for the most common types of PNB.

Brachial Plexus↗
PubMed2006

Ultrasound examination and localization of the sciatic nerve: a volunteer study.

BACKGROUND: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation. METHODS: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded. RESULTS: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion. CONCLUSIONS: These preliminary data show that a curved 2- to 5-MHz ultrasound probe provides good quality sciatic nerve imaging in the gluteal, infragluteal, and proximal thigh locations. Ultrasound-assisted sciatic nerve localization is potentially valuable for clinical sciatic nerve blocks.

Adult↗
PubMed2004

A survey of orthopedic surgeons' attitudes and knowledge regarding regional anesthesia.

UNLABELLED: We conducted a survey to explore the surgical attitudes and preferences regarding regional anesthesia among Canadian orthopedic surgeons. Surveys were returned by 468 (61%) of 768 surgeons. Forty-eight percent of respondents directed their patients' choice of anesthetic. Forty percent of surgeons directed their patients to choose regional anesthesia. The principal reasons for favoring regional anesthesia were less postoperative pain (32%), decreased nausea and vomiting (12%), and safety (14%). Reasons for not favoring regional anesthesia were delays in the induction of anesthesia (43%) and an unpredictable success rate (12%). This survey suggests that orthopedic surgeons are supportive of regional anesthesia. Barriers to increased popularity include perceived delays and unreliability. IMPLICATIONS: Orthopedic surgeons understand the benefits of and are supportive of the use of regional anesthesia in their practices. Barriers to increased popularity include perceived operating room delays and lack of reliability.

Adult↗
PubMed2003

Brachial plexus examination and localization using ultrasound and electrical stimulation: a volunteer study.

BACKGROUND: Current techniques of brachial plexus block are "blind," and nerve localization can be frustrating and time consuming. Previous studies on ultrasound-assisted brachial plexus blocks are mostly performed with scanning probes of 10 MHz or less. The authors tested the usefulness of a state-of-the-art, high-resolution ultrasound probe (up to 12 MHz) in identifying the brachial plexus in five locations of the upper extremity and in guiding needle advancement to target before nerve stimulation. METHODS: In this prospective observational study, 15 volunteers underwent brachial plexus examination using an L12-L5 MHz probe and a Philips-ATL 5000 ultrasound unit in the interscalene, supraclavicular, infraclavicular, axillary, and midhumeral regions. Thereafter, an insulated block needle was advanced under direct ultrasound guidance to target nerves before confirmation by electrical nerve stimulation in five volunteers in each of the interscalene, supraclavicular, and axillary regions. The quality of brachial plexus images, anatomic variations, and the technique of needle advancement for nerve localization were recorded. RESULTS: The brachial plexus components were successfully identified in the transverse view as round to oval hypoechoic structures with small internal punctuate echos in all regions examined except the infraclavicular area (visualized in 27% of the cases). The authors' technique of advancing the needle in-line with the ultrasound beam allowed moment-by-moment observation of the needle shaft and tip movement at the time of nerve localization. Hypoechoic structures were stimulated electrically and confirmed to be nerves. CONCLUSIONS: These preliminary data show that the high-resolution L12-L5 probe provides good quality brachial plexus ultrasound images in the superficial locations i.e., the interscalene, supraclavicular, axillary, and midhumeral regions. The needle technique described here for ultrasound-assisted nerve localization provides real-time guidance and is potentially valuable for brachial plexus blocks.

Adult↗
PubMed2003

Ultrasound-guided supraclavicular brachial plexus block.

UNLABELLED: In this study, we evaluated state-of-the-art ultrasound technology for supraclavicular brachial plexus blocks in 40 outpatients. Ultrasound imaging was used to identify the brachial plexus before the block, guide the block needle to reach target nerves, and visualize the pattern of local anesthetic spread. Needle position was further confirmed by nerve stimulation before injection. The block technique we describe aligned the needle path with the ultrasound beam. The block was successful after one attempt in 95% of the cases, with one failure attributable to subcutaneous injection and one to partial intravascular injection. Pneumothorax did not occur. Our preliminary data suggest that a high-resolution ultrasound probe can reliably identify the brachial plexus and its neighboring structures in the supraclavicular region. The technique of real-time guidance during needle advancement can quickly localize nerves. Distinct patterns of local anesthetic spread observed on ultrasound can further confirm accurate needle location. IMPLICATIONS: Real-time ultrasound imaging during supraclavicular brachial plexus blocks can facilitate nerve localization and needle placement and examine the pattern of local anesthetic spread.

Adult↗
PubMedDate not supplied

The sensitivity of motor response to nerve stimulation and paresthesia for nerve localization as evaluated by ultrasound.

BACKGROUND AND OBJECTIVE: Seeking paresthesia and obtaining a motor response to an electrical stimulus are the two most common methods of nerve localization for the performance of peripheral-nerve blocks. However, these two endpoints do not always correlate, and the actual sensitivity and specificity of either method remains unknown. The objective of this study is to determine the sensitivity of paresthesia and motor response to electrical nerve stimulation as tools for nerve localization when a 22-gauge insulated needle is used for the performance of axillary-nerve block. METHODS: After IRB approval and informed consent, 103 patients were enrolled. Real-time ultrasonography was used as the reference test. After needle-to-nerve contact was confirmed by ultrasonography, the patient was requested to report the presence of paresthesia, and a nerve stimulator was used to seek a motor response, with a stimulating current of 0.5 mA or less. RESULTS: One patient was excluded from analysis because of protocol violation. Paresthesia was found to be 38.2% sensitive and motor response was 74.5% sensitive for detection of needle-to-nerve contact. CONCLUSION: The very different and relatively low sensitivity of either technique may explain, in part, the lack of correlation previously reported between the 2 endpoints.

Adult↗
PubMedDate not supplied

An assessment tool for brachial plexus regional anesthesia performance: establishing construct validity and reliability.

BACKGROUND AND OBJECTIVES: Technical proficiency in regional anesthesia is often determined subjectively through in-training evaluations. Objective assessment tools improve these evaluations by providing criteria for measurement. However, any evaluation instrument needs to be valid and reliable before it is adopted into a curriculum. The purpose of this study is to determine the validity and reliability of a devised assessment of residents performing an interscalene brachial plexus block (ISB). METHODS: In this prospective study, 10 junior trainees and 10 senior trainees were videotaped performing an ISB. Junior trainees were defined as in their first year of anesthetic training and had performed less than 10 ISBs independently. Senior trainees had completed at least 1 year of anesthesia training and had performed greater than 10 ISBs independently. Two blinded expert raters independently evaluated the performance of the ISB using a checklist and global rating scale. Construct validity was established if the assessments were able to reliably discriminate between different levels of training. RESULTS: Senior trainees performed an ISB significantly better than junior trainees when assessed using the global rating scale (P < .05) and checklist (P < .001). The overall interrater reliability for the global rating scores was excellent (r = 0.85, P < .05) and was good for the checklist scores (r = 0.74, P < .05). CONCLUSIONS: Both assessment modalities were valid, in that they reliably discriminated between different levels of training. Objective measures of technical skills are feasible, timely, and improve the validity and reliability of competency assessments.

Anesthesia, Conduction↗
PubMedDate not supplied

Forearm rescue cuff improves tourniquet tolerance during intravenous regional anesthesia.

BACKGROUND AND OBJECTIVES: Tourniquet pain during intravenous regional anesthesia (IVRA) of the upper limb is common and can limit tourniquet inflation time. We hypothesize that a forearm rescue cuff is better tolerated than the traditional rescue cuff of a double-cuff tourniquet. METHODS: After Institutional Review Board (IRB) approval and informed consent, 10 healthy unmedicated volunteers took part in a prospective, randomized, cross-over study. Following inflation of the proximal tourniquet cuff on the upper arm, a standardized IVRA with 0.5% lidocaine, 0.6 mL/kg was administered. When the volunteer complained of tourniquet pain, or at 30 minutes, the initial cuff was changed to a rescue cuff. During session A, the rescue cuff was the traditional distal cuff of the double-cuff tourniquet. During session B, a single forearm cuff was used. When the volunteer experienced the same level of tourniquet pain, the rescue cuff was deflated and the study session ended. The tourniquet time for the rescue cuff, the visual analog scale (VAS) pain score, and the incidence and duration of side effects were recorded. RESULTS: The forearm rescue cuff was tolerated significantly longer than the arm rescue cuff (49 +/- 15 v 29 +/- 11 minutes, 95% confidence interval [CI] 7 to 32 minutes, P </=.005). When the forearm rescue cuff was used, VAS scores were lower and side effects were of shorter duration (6 +/- 5 v 15 +/- 7 minutes, P <.001). CONCLUSIONS: A forearm rescue cuff is better tolerated than an arm cuff double tourniquet during IVRA, allowing for longer tourniquet times. It is also associated with lower pain scores and shorter duration of local anesthetic side effects.

Adult↗