A Randomized Controlled Trial of Ultrasound Versus Nerve Stimulator Guidance for Axillary Brachial Plexus Block.

BACKGROUND: Ultrasound-guided techniques improve outcomes in regional anesthesia when compared with traditional techniques; however, this assertion has not been studied with novices. The primary objective of this study was to compare sensory and motor block after axillary brachial plexus block when performed by novice trainees allocated to an ultrasound- or nerve-stimulator-guided group. A secondary objective was to compare the rates of skill acquisition between the 2 groups. METHODS: This study was a prospective, randomized, observer-blinded, 2-arm controlled trial. Anesthesia trainees participating in this trial were novices to axillary brachial plexus block and sonography. All trainee participants underwent a standardized training program. The primary outcome was combined sensory and motor block in the relevant territories 30 minutes after completion of block. A global rating scale was used to assess trainee block performance. RESULTS: The study was ceased after 12 trainees completed 153 blocks. There was no difference between groups in combined motor/sensory score (P = 0.28) or as a function of block number (P = 0.38). There was no difference in onset between groups (P = 0.38). In both groups, there was an increase in the global rating scale score (P < 0.0001) and reduced preblock survey and block performance times (P = 0.001) with experience. CONCLUSIONS: We were unable to demonstrate a difference in the efficacy of axillary brachial plexus block performed by novices when ultrasound guidance was compared with a nerve stimulator technique. There was evidence of similarly improved clinical performance of novices in both groups.

Reference range for intrapatient variability in blood-pool and liver SUV for 18F-FDG PET.

UNLABELLED: (18)F-FDG PET qualitative tumor response assessment or tumor-to-background ratios compare targets against blood-pool or liver activity; standardized uptake value (SUV) semiquantitation has artifacts and is validated by a stable normal-tissue baseline. The aim of this study was to document the normal intrapatient range of scan-to-scan variation in blood-pool SUV and liver SUV and to identify factors that may adversely affect it (increase its spread). METHODS: Between July 2009 and June 2010, 132 oncology patients had 2 PET/CT scans. Patient preparation, acquisition, and reconstruction protocols were held stable, uniform, and reproducible. Mean SUV (body weight) values were obtained from 2-dimensional regions of interest in the aortic arch blood pool and in the right lobe of the liver. RESULTS: Of the 132 patients, 65 had lymphoma. Their mean age was 62.5 y. The group's mean serum glucose level was 6.0 mmol/L at the first visit and 5.9 mmol/L at the second visit. The mean (18)F-FDG dose was 4.1 MBq/kg at the first visit and 4.0 at the second. At the first visit, the group's mean blood-pool SUV was 1.55 (SD, 0.38); at the second, 1.58 (SD, 0.37)-not statistically different. The group's mean liver SUV was 2.17 (SD, 0.44) at the first visit and 2.29 (SD, 0.44) at the second (P = 0.005). Visit-to-visit intrapatient variation in blood-pool and liver SUVs had gaussian distributions. The variation in blood-pool SUV had a mean of 0.03 and SD of 0.42. The variation in liver SUV had a mean of 0.12 and SD of 0.50. Using 95th percentiles, the reference range in our patient population for intrapatient variation was -0.8 to 0.9 for blood pool SUV and -0.9 to 1.1 for liver SUV. Subanalysis by cancer type and chemotherapy suggested that the rise in liver SUV between the 2 visits was largely due to the commencement of chemotherapy, but no factors were identified as systematically affecting intrapatient variation, and no factors were identified as increasing its spread. CONCLUSION: In our patient cohort, the reference range for intrapatient variation in blood-pool and liver SUVs is -0.8 to 0.9 and -0.9 to 1.1, respectively.

Cancer on a mammogram is not memorable: readers remember their recalls and not cancers.

AIM: To determine if presence of cancer on a mammogram makes that mammogram more memorable. MATERIALS AND METHODS: A total of 100 mammograms (25 cancers) were grouped into 5 sets of 20 cases. Set pairs were presented in five reads to eight radiologist readers. Readers were asked to 'clear' or 'call back' cases, and at post-baseline reads to indicate whether each case was 'new' or 'old' (remembered from prior read). Two sets were presented only at baseline, to calculate each reader's false recollection rate. For cases presented more than once ('old' cases, 100 presentations) readers could have 'correct memory' or 'memory loss'. Memory performance was defined as odds ratio of correct memory to memory loss. Multivariate logistic data regression analysis identified predictors of memory performance from: reader, set, time since last read, presence of cancer, and whether the case was called back at the last read. RESULTS: Memory performance differed markedly between readers and reader identity was a highly significant predictor of memory performance. Presence of cancer was not a significant predictor of memory performance (odds ratio 0.77, 95% CI: 0.49-1.21). Whether the case was called back at the last read was a highly significant predictor (odds ratio 4.22, 95% CI: 2.70-6.61) for the model incorporating reader variability, and also the model without reader variability (odds ratio 2.67, 95% CI: 1.74-4.08). CONCLUSION: The only statistically significant predictor of radiologist memory for a mammogram was whether the radiologist 'called it back' at a prior reading round. Presence of cancer on a mammogram did not make it memorable.

Comparison of readers' detection of right-sided and left-sided breast cancers and microcalcifications.

INTRODUCTION: Aim of this study was to determine if there is a statistically and clinically significant difference in diagnostic performance (cancer diagnosis) and perceptual performance (microcalcification detection) when detecting left-sided or right-sided breast cancers and microcalcifications. METHODS: Eight radiologist readers (8-20 years experience in radiology, five current BreastScreen readers) read a set of 100 digital mammograms (23/100 had proven malignancies and 52/100 had confirmed microcalcifications) for three reads (random case order in each read). The same mammograms were presented on two reads, serving as the baseline reads. The data from these reads were used to calculate intra-observer variability (presented in an earlier study). The experimental read consisted of left-right mirror images of the original mammograms. In each read, the radiologists were requested to 'clear' or 'call-back' cases and to indicate if any microcalcifications (benign and malignant) were present on the mammograms. Reading conditions were standardised. RESULTS: Comparison of intra-reader performance difference for left-sided versus right-sided breast cancers and microcalcifications with intra-observer variability for breast cancer diagnosis and microcalcification detection, respectively, revealed no clinically significant difference between left-sided and right-sided detections. Per-case analysis showed more left-sided breast cancers and microcalcifications correctly detected. This left-right difference in detection did not reach statistical significance, P-value of 0.28 for cancer diagnosis and 0.74 for microcalcification detection. CONCLUSION: There is no statistically or clinically significant difference between left-sided and right-sided breast cancer diagnosis and microcalcification detection in a group of experienced radiologists. Individual reading patterns do not affect detection rates of left-sided and right-sided cancers and microcalcifications.

Intrareader variability in mammographic diagnostic and perceptual performance amongst experienced radiologists in Australia.

INTRODUCTION: The purpose of this study was, for a group of experienced radiologists, to identify the magnitude of and statistical significance of intrareader variability in mammographic diagnostic performance or cancer diagnosis and mammographic perceptual performance or microcalcification detection. METHODS: Eight radiologist readers (8-30 years experience in radiology, five current BreastScreen readers) read a set of 100 digital mammograms on two separate reads with random case orders. Twenty-three of the 100 had proven malignancies, and 52 of the 100 had confirmed microcalcifications. The same mammograms were presented for both reads. The radiologists were requested to clear or call back cases and to indicate if any benign and malignant microcalcifications were present on the mammograms. Reading conditions were standardised. RESULTS: Intrareader variability in accuracy was demonstrated to be between 0% and 6% for the diagnostic task of breast cancer diagnosis and between 0% and 16% for the perceptual task of microcalcification detection. Intrareader agreement in the group of readers was high; between 75% and 93% (κ=0.36-0.72) for cancer diagnosis and between 77.5% and 93% (κ=0.17-0.77) for microcalcification detection. There was no correlation between reader's experience in radiology or being a BreastScreen reader and level of intrareader variability in cancer diagnosis and microcalcification detection. CONCLUSION: There exists intrareader variability in diagnostic and perceptual performance. Despite this variability, intrareader agreement remains high.

Comparison of 3MP medical-grade to 1MP office-grade LCD monitors in mammographic diagnostic and perceptual performance.

INTRODUCTION: Picture archiving and communication systems images designed to be viewed on high-resolution medical-grade monitors are routinely viewed on office-grade monitors on the wards or at home. This study aimed to determine whether a statistically significant difference in diagnostic (cancer detection) and perceptual (microcalcification detection) performance exists between 3MP grade and 1MP office-grade monitors. METHODS: 3MP Dome medical-grade liquid crystal display (LCD) monitors (Planar, Beaverton, OR, USA) were compared to 1MP Dell office-grade LCD monitors (Dell Inc, Round Rock, TX, USA). Eight radiologists (reader experience 8-30 years) read the same set of 100 mammograms (23/100 with proven cancers and 52/100 with microcalcifications) presented in random order on three occasions separated by two time intervals of 12 weeks. Reads 1 and 3 utilised 3MP monitors and formed the baseline read. Read 2 utilised 1MP monitors and constituted the experimental read. Reading conditions were standardised. Readers were aware of which monitors they were using. Multivariate logistic regression analysis (to account for reader variability and monitor impact) was performed to assess for statistical significance. RESULTS: At α = 5%, confidence intervals analysis comparing the measured parameters between 1MP to 3MP monitors demonstrated no statistically significant difference in diagnostic and perceptual performance for the reader group. In cancer detection (the diagnostic task), reader accuracy remained high irrespective of monitor type. Regression analysis comparing performance with 1MP against 3MP monitors found P values of 0.693 and 0.324 for diagnostic and perceptual performance, respectively. CONCLUSION: There were no statistically and clinically significant differences between 3MP and 1MP monitors in mammographic diagnostic and perceptual performance. Comparable performance may be due to compensatory behaviour by readers.

Preliminary results of the Australasian Regional Anaesthesia Collaboration: a prospective audit of more than 7000 peripheral nerve and plexus blocks for neurologic and other complications.

BACKGROUND AND OBJECTIVES: Peripheral nerve blockade is associated with excellent patient outcomes after surgery; however, neurologic and other complications can be devastating for the patient. This article reports the development and preliminary results of a multicenter audit describing the quality and safety of peripheral nerve blockade. METHODS: From January 2006 to May 2008, patients who received peripheral nerve blockade had data relating to efficacy and complications entered into databases. All patients who received nerve blocks performed by all anesthetists during each hospital's contributing period were included. Patients were followed up by phone to detect potential neurologic complications. The timing of follow-up was either at 7 to 10 days or 6 weeks postoperatively, depending on practice location and time period. Late neurologic deficits were defined as a new onset of sensory and/or motor deficit consistent with a nerve/plexus distribution without other identifiable cause, and one of the following: electrophysiologic evidence of nerve damage, new neurologic signs, new onset of neuropathic pain in a nerve distribution area, paresthesia in relevant nerve/plexus distribution area. RESULTS: A total of 6950 patients received 8189 peripheral nerve or plexus blocks. Of the 6950 patients, 6069 patients were successfully followed up. In these 6069 patients, there were a total of 7156 blocks forming the denominator for late neurologic complications. Thirty patients (0.5%) had clinical features requiring referral for neurologic assessment. Three of the 30 patients had a block-related nerve injury, giving an incidence of 0.4 per 1000 blocks (95% confidence interval, 0.08-1.1:1000). The incidence of systemic local anesthetic toxicity was 0.98 per 1000 blocks (95% confidence interval, 0.42-1.9:1000). CONCLUSIONS: These results indicate that the incidence of serious complications after peripheral nerve blockade is uncommon and that the origin of neurologic symptoms/signs in the postoperative period is most likely to be unrelated to nerve blockade.

Ultrasound-guided midthigh sciatic nerve block-a clinical and anatomical study.

BACKGROUND AND OBJECTIVES: Ultrasound-guided sciatic nerve block is a relatively new regional anesthesia technique with few descriptions in the literature. The objective of this study was to assess the ease with which the sciatic nerve could be imaged in the midthigh region using ultrasound and to describe the anatomy surrounding the sciatic nerve at this location. METHODS: In this prospective observational study, 40 patients scheduled for surgery where sciatic nerve block was indicated were scanned between the gluteal and the popliteal regions using an ultrasound machine (Vivid-i, GE Healthcare, Chalfont St. Giles, Bucks, UK). Patients then received real time ultrasound-guided sciatic nerve block. Validation of the ultrasound image of the sciatic nerve was achieved using nerve stimulation. Description and confirmation of the anatomy surrounding the sciatic nerve was based on a review of anatomical texts and an anatomical study on 5 unembalmed cadavers. RESULTS: The sciatic nerve was identified with ultrasound and its image validated using nerve stimulation in 38 of 40 patients (95%). In 15 patients (37.5%) nerve stimulation was required to confirm identification of the sciatic nerve. Surrounding muscles (biceps femoris, vastus lateralis, and adductor magnus) and fascial planes (lateral intermuscular septum) were identified as sonographic landmarks and were confirmed in the anatomical study. CONCLUSIONS: Ultrasonic identification of the sciatic nerve at the midthigh level can be achieved; however, in this study, 37.5% of patients required nerve stimulation to confirm its sonographic appearance. Target nerve localization and the subsequent performance of the sciatic nerve block may be enhanced by recognition of surrounding muscular and fascial structures which were also identified using ultrasound.