Static palpation ain't easy: Evaluating palpation precision using a topographical map of the lumbar spine as a reference

INTRODUCTION

Clinicians commonly use manual therapy to treat low back pain by palpating the spine to identify the spinous processes. This study aims to evaluate the ability of experienced clinicians to consistently locate the spinous processes from S1 to T12 through palpation. The results will be compared to topographical data representing the lumbar lordosis at baseline and four follow-up time points.

MATERIALS AND METHODS

In a prior prospective randomized trial, experienced clinicians used palpation to locate the lumbar spinous processes (S1-T12) and then digitized these locations in three-dimensional space. The same digitizing equipment was then used to continuously collect three-dimensional position data of a wheel that rolled along the back's surface through a trajectory that connected the previously digitized locations of the spinous processes. This process was repeated at 4 days, 1, 4, and 12 weeks. The resulting lordosis trajectories were plotted and aligned using the most anterior point in the lordosis to compare the locations of the spinous processes identified in different trials. This way, spinous palpation points could be compared to surface topography over time. Intra- and interrater reliability and agreement were estimated using intraclass correlations of agreement and Bland-Altman limits of agreement.

RESULTS

Five clinicians palpated a total of 119 participants. The results showed a large degree of variation in precision estimates, with a mean total value of 13 mm (95%CI = 11;15). This precision error was consistent across all time points. The smallest precision error was found at L5, followed by S1 File, after which the error increased superiorly. Intra- and interrater reliability was poor to moderate.

CONCLUSIONS

Comparison of palpation results to a topographic standard representing the lumbar lordosis is a new approach for evaluating palpation. Our results confirm the results of prior studies that find palpation of lumbar spinous processes imprecise, even for experienced clinicians.

Administration of combined spinal epidural anesthesia with ultrasound-assisted positioning in obese patients undergoing open hysterectomy: A randomized controlled trial

BACKGROUND

Administration of combined spinal epidural anesthesia (CSEA) with traditional landmark-guided positioning can be challenging in patients with high body mass index (BMI). The popularization of ultrasound technology may effectively solve these problems. However, reports on the administration of CSEA ultrasound-assisted positioning in obese populations are relatively limited and have made inconsistent conclusions. We aimed to investigate the ability of ultrasound-assisted positioning to improve the success rate of CSEA in obese patients.

METHODS

Overall, 118 adult women with a BMI ≥ 30 kg/m2 who scheduled to undergo open hysterectomy and received CSEA were recruited. Finally, 108 patients were enrolled and randomly assigned to 2 groups: the ultrasound-assisted positioning group (group A) and traditional landmark-guided positioning group (group B). Ultrasound-assisted or landmark-guided positioning was employed to locate the puncture interspace before anesthesia. The primary outcomes were the success rate of first attempt and number of attempts. The secondary outcomes were the patient positioning accuracy, positioning time, CSEA operation time, patient-satisfaction scores, anesthesia characteristics, and complications of CSEA.

RESULTS

The success rate of patient first puncture attempt in group A was significantly higher than that in group B (78.4% vs 52.9%, P = .007). The total number of punctures was lower in group A than that in groups B (average rank 44.54 vs 58.46, P = .005). Using ultrasound positioning as the gold standard, the accuracy of landmark-guided location was only 67%. Positioning time in croup A was longer in group A than that in group B (P = .004), while CSEA operation time spent in Group A was less than that in Group B (P < .001). Patient satisfaction score in group A was significantly higher than that in group B (P = .002). The successful puncture interspace in group A were more likely at L3-4 than that in group B (P = .02).

CONCLUSION

The success rate of first puncture attempt and positioning accuracy in CSEA with ultrasound-assisted is significantly higher than those based on landmark-guided location in obese patients.

Ultrasound-based Accuro system versus traditional palpation technique for neuraxial anaesthesia: A systematic review and meta-analysis of randomised controlled trials

INTRODUCTION

This review evaluates the efficacy and safety of Accuro, a handheld ultrasound device, compared to the palpation technique for neuraxial anaesthesia. Accuro provides real-time imaging guidance, potentially improving accuracy and efficiency.

METHODS

A comprehensive search across six electronic databases identified randomised clinical trials comparing Accuro with palpation for neuraxial anaesthesia. Risk ratios or mean differences with 95% confidence intervals (CIs) were calculated using a random-effects model. Bias risk was evaluated using the Cochrane Risk of Bias tool.

RESULTS

Five studies (n=369) met the inclusion criteria. Accuro showed a favourable risk ratio for first insertion success (1.44 [95% CI [1.01, 2.05], p=0.05]). It significantly reduced needle skin passes (MD -0.63; 95% CI [-1.05, -0.21]; p<0.01), but not needle redirection (MD -1.31; 95% CI [-2.71, 0.11]; p=0.07). Procedure time was shorter in palpation (MD 127.82; 95% CI [8.68, -246.97]; p=0.04). Four studies had a low risk of bias; one had some concerns.

CONCLUSION

Accuro can potentially improve success rates and reduce skin passes in neuraxial anaesthesia. Further trials with larger samples are needed, especially in patients with anticipated difficulties.

Factors associated with failed epidural blood patch after accidental dural puncture in obstetrics: a prospective, multicentre, international cohort study

BACKGROUND

Epidural blood patch is commonly used for management of post-dural puncture headache after accidental dural puncture. The primary aim was to determine factors associated with failed epidural blood patch.

METHODS

In this prospective, multicentre, international cohort study, parturients ≥18 yr receiving an epidural blood patch for treatment of post-dural puncture headache were included. Failed epidural blood patch was defined as headache intensity numeric rating scale (NRS) score ≥7 in the upright position at 4, 24, or 48 h, or the need for a second epidural blood patch, and complete success by NRS=0 at 0-48 h after epidural blood patch. All others were considered partial success. Multinominal logistic regression was used for statistical analyses with P<0.01 considered statistically significant.

RESULTS

In all, 643 women received an epidural blood patch. Complete data to classify failure were available in 591 (91.9%) women. Failed epidural blood patch occurred in 167 (28.3%) patients; 195 (33.0%) were completely successful and 229 (38.7%) partially successful. A total of 126 women (19.8%) received a second epidural blood patch. A statistically significant association with failure was observed in patients with a history of migraine, when the accidental dural puncture occurred between lumbar levels L1/L3 compared with L3/L5 and when epidural blood patch was performed <48 h compared with ≥48 h after accidental dural puncture. In patients having radiological investigations, three intracranial bleeds were diagnosed.

CONCLUSIONS

Failed epidural blood patch occurred in 28.3% of women. Independent modifiable factors associated with failure were higher lumbar level of accidental dural puncture and short interval between accidental dural puncture and epidural blood patch. A history of migraine was associated with a higher risk of second epidural blood patch.

CLINICAL TRIAL REGISTRATION

NCT02362828.

Comparing the minimum local anesthetic dose of ropivacaine in real-time ultrasound-guided spinal anesthesia and traditional landmark-guided spinal anesthesia: a randomized controlled trial of knee surgery patients

Background

Through previous studies and clinical practice, we have found that real-time ultrasound-guided (UG) spinal anesthesia (SA) and traditional landmark-guided (LG) SA each require a different minimum local anesthetic dose (MLAD) of ropivacaine. For this study, we used Dixon’s up-and-down sequential method to analyze and compare the MLAD of different ropivacaine concentrations required for the UG and LG SA methods.

Methods

A total of 120 patients undergoing knee surgery were consecutively recruited and randomly divided into four groups (30 patients per group). These groups were categorized as follows: Group I: high ropivacaine ultrasound-guided (HRUG), Group II: low ropivacaine ultrasound-guided (LRUG), Group III: high ropivacaine landmark-guided (HRLG), and Group IV: low ropivacaine landmark-guided (LRLG). SA was established by a bolus administration of up-and-down doses of 0.75% or 0.5% plain ropivacaine. Initial doses of 16, 18, 12, and 14 mg were administered to groups I–IV, and after that, increased or decreased by 1.5 mg according to dose effectiveness. Upon identifying the intervertebral puncture level, a lumbar X-ray was performed with metal markers, and actual radiographic findings were identified and compared to the initial markings.

Results

For UG groups, the MLAD in the LRUG group was significantly higher than in the HRUG group [20.192 mg (95% CI, 19.256–21.174) versus 17.176 mg (95% CI, 16.276–18.124), respectively; P<0.001]. For LG groups, the MLAD in the LRLG group was significantly higher than in the HLRG group [14.478 mg (95% CI, 13.364–15.500) versus 13.201 mg (95% CI, 11.959–14.571), respectively; P=0.047]. When comparing both high ropivacaine groups (HRGs: I/III) to the low ropivacaine groups (LRGs: II/IV), we found that both UG subgroups (I/II) had a significantly higher MLAD than LG subgroups (III/IV) (P<0.001). US identified L4–5 in up to 90% of cases. Comparatively, palpation was successful in only 33.3% of patients. The rates of cephalad localization by US and palpation were 6.67% vs. 66.67%, respectively (P=0.002).

Conclusions

We found a higher MLAD of ropivacaine was required for UG SA at the L4–5 level due to the method providing a more accurate (less cephalad) localization than traditional LG SA.

Trial Registration

Chinese Clinical Trial Registry ChiCTR2000033158.

Accuro ultrasound-based system with computer-aided image interpretation compared to traditional palpation technique for neuraxial anesthesia placement in obese parturients undergoing cesarean delivery: a randomized controlled trial

PURPOSE

Recently, a new handheld ultrasound-based device, called Accuro, has been commercialized with a real-time automated interpretation of lumbar ultrasound images. We hypothesized that the handheld ultrasound device would improve the efficacy and safety of combined spinal-epidural anesthesia (CSEA) for cesarean delivery in obese parturients.

METHODS

Eighty parturients with a body mass index > 30 kg∙m^-2 scheduled for elective cesarean delivery were randomly allocated equally (palpation group and ultrasound group). The primary outcome was the first insertion success rate. Secondary outcomes were the time taken to identify the needle puncture site, duration of CSEA procedure, the total time, the rate of parturients who require needle redirections, the number of skin punctures, changes in the intended interspace, and the incidence of complications.

RESULTS

Compared to the palpation group, the first insertion success rate was significantly higher (72.5% vs. 40.0%; P = 0.003), and time taken to identify the needle puncture site was less (30 [26-36] vs. 39 [32-49] seconds; P = 0.001) in the ultrasound group. The rate of parturients who required needle redirections (40.0% vs. 72.5%; P = 0.003) and the incidence of paresthesia were both lower (7.5% vs. 45.0%; P < 0.001). The other outcomes had no significant difference between groups. The mean difference between the epidural depth measured by the handheld ultrasound and needle depth was - 0.29 cm [95% limit of agreement, - 0.52 to - 0.05].

CONCLUSIONS

Our study suggests using the Accuro ultrasound device can enhance the efficacy and safety of CSEA in obese parturients when executed by experienced anesthesiologists, and its automated estimation of epidural depth is accurate.

Minimum local anesthetic dose of ropivacaine in real-time ultrasound-guided intraspinal anesthesia for lower extremity surgery: a randomized controlled trial

Background

Despite the many advantages real-time ultrasound-guided lumbar anesthesia has over traditional lumbar anesthesia, it seemingly involves a much higher dose of ropivacaine. This study aimed to determine the minimum local anesthetic dose (MLAD) and the 95% confidence interval of ropivacaine at different concentrations in real-time ultrasound-guided lumbar anesthesia for lower extremity surgery.

Methods

A total of 60 patients who were consecutively scheduled for selective lower extremity surgery were enrolled. The patients were randomly divided into two groups, which each received different concentrations of ropivacaine at different initial dosages when Dixon's up-and-down sequential method was applied. The high ropivacaine group and the low ropivacaine group received 0.75% and 0.5% ropivacaine, respectively. The patients' baseline characteristics, the MLAD, and the 95% confidence interval were assessed. The highest level of sensory block, time to reach the T10 sensory block, duration for sensory blocks higher than T10, highest plane for sensory block, and onset time and duration for motor block were recorded. Comparisons were also made between the patients' vital signs and adverse reactions.

Results

The minimum local anaesthetic dose (MLAD) and 95% confidence interval in the high ropivacaine group and the low ropivacaine group were 17.176 (16.276 to 18.124) and 20.192 (19.256 to 21.174) mg, respectively. Moreover, motor block maintenance was greatly reduced in the 0.5% ropivacaine compared to the 0.75% ropivacaine group (P=0.0309).

Conclusions

In real-time ultrasound-guided intraspinal anesthesia for lower extremity surgery, both 0.75% and 0.5% ropivacaine provide satisfactory anesthesia. Our results suggest that shortened motor block duration can hold benefits for patients including earlier mobilization and a quicker rehabilitation process.

Sacral anatomical interspace landmark for lumbar puncture in pregnancy: A randomized trial

OBJECTIVE

To determine whether the sacral anatomical interspace landmark (SAIL) technique is more accurate than the classic intercristal line (ICL) technique in pregnant patients and to assess the percentage of clinical determinations above the third lumbar vertebra.

METHODS

In this prospective, randomized, open-label trial, there were 110 singleton pregnant patients with gestational age greater than 37 weeks included. Selection procedure was a convenience sample of pregnant patients who presented for office visits or vaginal or cesarean delivery between March 15 and July 31, 2018, at a single-center obstetric tertiary care university hospital. Both techniques were evaluated by 2 physicians independently assessing each method. Before data collection, we hypothesized that the SAIL technique would be more accurate than the ICL technique in determining the L4-L5 interspace, and that the SAIL technique would produce more estimations below the third lumbar vertebra than the ICL technique. Therefore, the primary outcome was accuracy in identifying the L4-L5 lumbar interspace with SAIL vs ICL. The secondary outcome was difference in clinical assessments above the third lumbar vertebra. Both outcomes were measured via ultrasonography.

RESULTS

Patients were 31 ± 5 years of age (mean ± SD) and had body mass index of 31.8 ± 5.7 kg/m² and gestational age of 38.8 ± 1.1 weeks. A total of 110 patients were analyzed. SAIL correctly identified the L4-L5 interspace 49% of the time vs 8% using ICL (p < 0.0001). Estimations above L3 were 1% for SAIL vs 31% for ICL (p < 0.0001).

CONCLUSIONS

Our study shows improved accuracy in identifying intervertebral space using the SAIL technique; this may prevent direct mechanical trauma to the conus medullaris when lumbar punctures are performed in pregnancy.

CLINICALTRIALSGOV IDENTIFIER

NCT03433612.

Inadvertent neuraxial block placement at or above the L1-L2 interspace in the super-obese parturient: a retrospective study

BACKGROUND

Increasing body mass index (BMI) increases the difficulty of neuraxial procedures. We hypothesized that it may put patients at risk for inappropriately high dural puncture. The accuracy of anesthesiologists' estimates of the interspinous level in super-obese parturients has not been studied. We evaluated the frequency of inadvertently high epidural and/or intrathecal catheter placement (at or above the L1/L2 interspace) in parturients of BMI ≥50 kg/m².

METHODS

Inclusion criteria for this retrospective study were women with a BMI ≥50 kg/m² who delivered by cesarean with an epidural or intrathecal catheter. The primary outcome was the percentage of catheters placed at or above L1/L2, determined by reviewing the retained foreign object radiograph. Secondary outcomes were agreement between the estimated and actual catheter location and subgroup analysis of catheters placed under ultrasound guidance.

RESULTS

After excluding 15 cases for which the catheter location could not be determined and 10 cases for which the estimated level of insertion was not recorded, 125 cases were included. Inadvertent high placement occurred in 26/125 (21%, 95% confidence interval (CI) 15% to 29%) patients. There was poor agreement between the estimated and actual catheter location (27% accurate, unweighted κ-statistic 0.02). Eleven of 39 catheters placed with ultrasound (28%, 95% CI 17% to 44%) were at or above L1/L2 compared with 15/86 catheters placed without ultrasound (17%, 95% CI 11% to 27%, P=0.17). There were no neurological complications.

CONCLUSIONS

A high rate of inadvertently high epidural or intrathecal catheter placement occurs in super-obese parturients. Ultrasound did not prevent this.

Recommendations on the Use of Ultrasound Guidance for Adult Lumbar Puncture: A Position Statement of the Society of Hospital Medicine

When ultrasound equipment is available, along with providers who are appropriately trained to use it, we recommend that ultrasound guidance should be used for site selection of lumbar puncture to reduce the number of needle insertion attempts and needle redirections and increase the overall procedure success rates, especially in patients who are obese or have difficult-to-palpate landmarks. We recommend that ultrasound should be used to more accurately identify the lumbar spine level than physical examination in both obese and nonobese patients. We suggest using ultrasound for selecting and marking a needle insertion site just before performing lumbar puncture in either a lateral decubitus or sitting position. The patient should remain in the same position after marking the needle insertion site. We recommend that a low-frequency transducer, preferably a curvilinear array transducer, should be used to evaluate the lumbar spine and mark a needle insertion site. A high-frequency linear array transducer may be used in nonobese patients. We recommend that ultrasound should be used to map the lumbar spine, starting at the level of the sacrum and sliding the transducer cephalad, sequentially identifying the lumbar spine interspaces. We recommend that ultrasound should be used in a transverse plane to mark the midline of the lumbar spine and in a longitudinal plane to mark the interspinous spaces. The intersection of these two lines marks the needle insertion site. We recommend that ultrasound should be used during a preprocedural evaluation to measure the distance from the skin surface to the ligamentum flavum from a longitudinal paramedian view to estimate the needle insertion depth and ensure that a spinal needle of adequate length is used. We recommend that novices should undergo simulation-based training, where available, before attempting ultrasound-guided lumbar puncture on actual patients. We recommend that training in ultrasound-guided lumbar puncture should be adapted based on prior ultrasound experience, as learning curves will vary. We recommend that novice providers should be supervised when performing ultrasound-guided lumbar puncture before performing the procedure independently on patients.

Point-of-Care Ultrasound in Established Settings

The original and most widely accepted applications for point-of-care ultrasound (POCUS) are in the settings of trauma, shock, and bedside procedures. Trauma was the original setting for the introduction of POCUS and has been standardized under the four-plus view examination called the Focused Assessment with Sonography in Trauma (FAST). This examination was found to be especially practice changing for achieving rapid diagnoses in critically ill patients who are too unstable for the delays and transportation inherent in more advanced imaging with computed tomography. This application was broadened from the critically ill trauma patient to any critically ill patient, particularly the patient in undifferentiated shock. Although the Focused Assessment with Sonography in Trauma examination originally focused on sources of hemorrhage causing hypovolemic shock, POCUS also can quickly differentiate cardiogenic, obstructive, and distributive shock and help identify the more specific etiology such as massive pulmonary emboli, pericardial tamponade, and pneumothoraces. By expediting diagnosis, POCUS facilitates faster definitive treatment of life-threatening conditions. In pursuing treatment, US continues to serve a role in the form of visually guiding many procedures that were previously done blindly. US guidance of procedures has improved the safety of central line insertion, thoracentesis, and paracentesis, and has an emerging role in lumbar puncture. Experience in bedside US is becoming a vital tool in the clinician's bedside assessment and management, filling a void between the stethoscope and the more advanced studies and interventions available through radiology. Understanding the strengths and limitations of US enables clinicians to identify the appropriate situations in which they can apply this tool confidently.

Lumbar Ultrasonography for Obstetric Neuraxial Blocks: Sonoanatomy and Literature Review

Ultrasonography has gained popularity in recent years among anaesthesiologists and being used widely for regional blocks and central venous catheterization. Ultrasonography for neuraxial blocks was found beneficial especially for determining the correct needle insertion site and estimating the needle insertion depth of epidural space. In many recent studies, ultrasound guided epidural and spinal blocks have been evaluated among obstetric patients. Pre-procedural lumbar ultrasonography and real time ultrasound guidance for neuraxial blocks was the subject of these studies. We aimed to evaluate lumbar ultrasonography for obstetric neuraxial blocks. We describe the principles of lumbar ultrasound scanning techniques and present a practical review of lumbar sonoanatomy. We discuss the potential impact and benefits of the ultrasound-guided technique in improving obstetric neuraxial blocks and limitations of its use in clinical practice, based on previous studies.

Ultrasound diagnosis and therapeutic intervention in the spine

Spine pathology afflicts people across the globe and is responsible for a large portion of physician visits and healthcare costs. Imaging such as plain radiographs, CT, MRI, and ultrasound is vital to assess structure, function, and stability of the spine and also provide guidance in therapeutic interventions. Ultrasound utilization in spine conditions is less ubiquitous, but provides benefits in low costs, portability, and dynamic imaging. This study assesses ultrasound efficacy in diagnosis and therapeutic interventions for spine pathology. A systematic review conducted via PubMed, MEDLINE, and Google Scholar identified 3,630 papers with eventual inclusion of 73 papers with an additional 21 papers supplemental papers subsequently added. Findings highlighted ultrasound utilization for different structural elements of the spine such as muscle, bone, disc, ligament, canal, and joints are presented and compared with radiographs, CT, and MRI imaging where relevant. Spinal curvature and mobility are similarly presented. Ultrasound efficacy for guided therapeutics about the spine is presented and assessed against other modalities. Ultrasound is a widely used and efficacious modality to guide injections about the spine. Diagnostic utility is less well studied, but shows promise in assessing fractures, posterior ligamentous stability, and intra-operative hardware placement. The low cost, portability, and dynamic imaging ability make it an attractive modality particularly for developing health systems and resource limited environments such as combat settings and the International Space Station. Further study is recommended before broad adoption in diagnostics.

Success rate of elective lumbar puncture at a major Melbourne neurology unit

Background:

Lumbar puncture remains an important diagnostic and therapeutic procedure in clinical neurology. Failed lumbar punctures can result in a delay in diagnosis. Ultrasound may have a role in increasing successful lumbar puncture rates.

Methods:

Data was collected retrospectively from patient notes who had an elective lumbar puncture from January 2012 to August 2015.

Results:

During this four-year period, 74 patients underwent a neurologic outpatient lumbar puncture. Of these 74 lumbar punctures, 53 were successful (28% failure rate).

Conclusions:

This study found a 28% failure rate of conventional palpation-guided lumbar puncture. Ultrasound may provide an exciting opportunity to optimize lumbar puncture procedures and improve patient experience and diagnostic outcomes.

Conus medullaris trauma: is there a greater risk in parturients?

BACKGROUND

There is some evidence that anaesthetists often perform neuraxial blocks at a higher lumbar interspace than intended. It may be questioned whether parturients are at greater risk for neurological damage when the dura is perforated at a more cephalad interspace than L2-L3.

METHODS

Thirty-six patients scheduled for elective Caesarean delivery under CSE anaesthesia were selected for study. Using a B-D Durasafe Adjustable needle combination, the skin-to-epidural distance and the width of the epidural space were measured and matched with 36 female patients undergoing the same anaesthetic technique for orthopaedic procedures.

RESULTS

Pregnant patients had a higher bodyweight (77 vs. 67 kg, p = 0.007) than those scheduled for orthopaedic surgery. The skin-to-epidural distance was similar in both groups (5.3 vs. 5.1 cm, p = 0.3). The width of the epidural space was 1.1 mm larger in parturients (8.2 vs. 7.1 mm, p = 0.04). More patients in this group had tip-to-tip distances exceeding 10 mm (25 vs. 12%).

CONCLUSION

The greater epidural space or tip-to-tip distance between the epidural and spinal needle points in term parturients results in a lower margin of safety with respect to the distance from the dura to spinal cord or conus medullaris. Puncturing the correct interspace is, therefore, of crucial importance in pregnant patients.

Ultrasonography helps emergency physician identify the best lumbar puncture site under the conus medullaris

Background

Ultrasonography – assisted lumbar puncture helps physicians identify traditional anatomical landmarks. However, it could help to overcome the anatomical dogmas and thus identify the best interspinous space under the medullary cone.

Methods

Traditional anatomical landmarks were reported on a tracing paper in patients with an indication for lumbar puncture. Then, ultrasonography was used to locate the optimal interspinous level defined as the widest subarachnoid space located below the conus medullaris. Primary endpoint was the distance between traditional and ultrasound landmarks.

Results

Fifty-seven patients were included. Seven emergency physicians practiced the procedure. The median absolute distance between traditional anatomical landmarks and ultrasound marking was 32 [interquartile (IQR) 27 – 37] mm. The inter-spinous space identified in the two procedures was different in 68% of the cases.

Conclusions

Ultrasound not only allows us to better identify anatomical structures before lumbar puncture, but it also allows us to choose a site of puncture different from recommendations.

SLIDE: automatic spine level identification system using a deep convolutional neural network

PURPOSE

Percutaneous spinal needle insertion procedures often require proper identification of the vertebral level to effectively and safely deliver analgesic agents. The current clinical method involves "blind" identification of the vertebral level through manual palpation of the spine, which has only 30% reported accuracy. Therefore, there is a need for better anatomical identification prior to needle insertion.

METHODS

A real-time system was developed to identify the vertebral level from a sequence of ultrasound images, following a clinical imaging protocol. The system uses a deep convolutional neural network (CNN) to classify transverse images of the lower spine. Several existing CNN architectures were implemented, utilizing transfer learning, and compared for adequacy in a real-time system. In the system, the CNN output is processed, using a novel state machine, to automatically identify vertebral levels as the transducer moves up the spine. Additionally, a graphical display was developed and integrated within 3D Slicer. Finally, an augmented reality display, projecting the level onto the patient's back, was also designed. A small feasibility study [Formula: see text] evaluated performance.

RESULTS

The proposed CNN successfully discriminates ultrasound images of the sacrum, intervertebral gaps, and vertebral bones, achieving 88% 20-fold cross-validation accuracy. Seventeen of 20 test ultrasound scans had successful identification of all vertebral levels, processed at real-time speed (40 frames/s).

CONCLUSION

A machine learning system is presented that successfully identifies lumbar vertebral levels. The small study on human subjects demonstrated real-time performance. A projection-based augmented reality display was used to show the vertebral level directly on the subject adjacent to the puncture site.

Comparison between two anatomic landmarks using ultrasonography in spinal anesthesia: a randomized controlled trial

BACKGROUND AND OBJECTIVE

Tuffier's line is the most used anatomic landmark in clinical practice. We aimed to compare the accuracy of Tuffier's line with a landmark that joins the two lowest points of the tenth rib on the flanks with the help of ultrasound.

METHODS

A prospective, randomized, controlled, double-blinded trial was performed with 200 patients aged between 18 and 50. Patients taller than 180 cm or shorter than 150 cm, or with body mass index >30 kg/m² were excluded. The first anesthesiologist examined Group T according to Tuffier's line and Group R according to the tenth rib line and marked L_4-5. Only one anesthesiologist evaluated the marked level with ultrasound for accuracy of the anesthesiologist's examination.

RESULTS

There was no difference between groups for demographic and surgical data (p > 0.05). However, we observed a significant difference between the two techniques for success rate (60% in group T vs. 74% in group R) at estimation of correct level (p < 0.05). There was no correlation between success of estimation and patients' demographic data.

CONCLUSION

We conclude that the tenth rib line is better than Tuffier's line for accuracy with palpation. However, it must be confirmed by further studies including more than one examiner for palpation and also include different patient populations.

Inaccurate level of intervertebral space estimated by palpation: The ultrasonic revelation

BACKGROUND

Spinal cord injury resulting from spinal anesthesia is a rare, but an alarming scenario. The most likely cause is believed to be misjudged level of intervertebral space (IVS). We evaluated the accuracy of palpation method to locate IVS with the ultrasonography.

MATERIALS AND METHODS

A total of 109 patients undergoing spinal anesthesia were included in this observational, double-blind study. First anesthesiologist was asked to mark IVS using palpation method. It was followed by ultrasonographic assessment by another anesthesiologist who was unaware of the level estimated for the mark. We evaluated the accuracy of palpation method in sitting and lateral position as well as the impact of the anesthesiologist's experience (Trainee/Consultant).

STATISTICAL ANALYSIS USED

Association between the gender, anthropometric parameters, type of anesthesiologists assessing the IVS, and the level of agreement were identified using Chi-square test. The agreement between palpation method and ultrasound assessment of IVS was analyzed using kappa statistic. P < 0.05 was defined as statistical significance.

RESULTS

The IVS located by palpation method was in agreement with ultrasound location in 37.14% of the patients. There were no statistically significant differences found in terms of demographic data (sex, age, height, weight, or body mass index [BMI]) between agreement and disagreement group. The rate of errors was found to be significantly higher (P = 0.01) among the trainees (74.51%) than the consultants (51.86%). The rate of errors was not different between the sitting and lateral position. The frequency of errors was more common in cephalad direction (53.31.5%) compared to caudal direction (9.52%). The misidentified spaces were as high as three spaces above the intended space while in caudal direction it differed by only one space.

CONCLUSION

The accuracy of palpation method controlled by ultrasound is 37.14% and differs by 1-3 IVS in cephalad direction (53.31%). The accuracy is affected by anesthesiologist's experience but remains unaffected by age, sex height, BMI, and patient positioning.

Ultrasound-guided evaluation of the lumbar subarachnoid space in lateral and sitting positions in pregnant patients to receive elective cesarean operation

BACKGROUND AND OBJECTIVE

The aim was to compare visibility of the spinal space in sitting and lateral positions, number of attempts, spinal needle depth, skin-dura mater distance and the possible complications; in application of spinal anesthesia, using ultrasound in pregnant patients scheduled to receive elective cesarean operations.

METHODS

The study was conducted prospective-randomly after receiving approval from the ethics committee and the patients' permission. ASA I-II 50 pregnant patients were divided into two groups. The patients in Group SP were those placed in a sitting position and the patients in Group LP were those placed in a lateral position. In both groups, the skin-dura mater distance was recorded through an out-of plane technique accompanied by ultrasound. The depth of the spinal needle was measured. The number of attempts, the level of attempts recorded. The degree of visibility of the vertebral space was observed through ultrasound and was numerically scored. Intraoperative and postoperative complications were recorded.

RESULTS

There was no difference between the number of attempts, Modified Bromage Scale and mean measurements of skin-dura mater distance observed through ultrasound. The mean needle depths of Group LP were statistically found significantly higher than Group SP (p=0.002).

CONCLUSION

Our study supports the notion that access to the skin-dura mater distance is longer in the lateral decubitus position when skin-dura mater distance is evaluated by measuring needle depth.

Ultrasound in obstetric anesthesia

Ultrasound has permeated the practice of anesthesiology and is becoming an essential tool for the obstetric anesthesiologist in the labor and delivery suite. The most common applications include guidance for neuraxial (epidural and spinal) anesthesia and acute pain nerve blocks, as well as guidance for central and peripheral vascular access. Obstetric anesthesiologists are becoming increasingly familiar with diagnostic applications, including transthoracic echocardiography (TTE) and lung and gastric ultrasound. There is intense interest in developing standard curricula for achieving competency in ultrasound skills during residency training and expanding the role of ultrasound in education and research.

A randomized controlled trial of preinsertion ultrasound guidance for spinal anaesthesia in pregnancy: outcomes among obese and lean parturients: ultrasound for spinal anesthesia in pregnancy

PURPOSE

The present study was conducted to examine if preinsertion lumbar ultrasound scanning helps with performance of spinal puncture, as a tool for decreasing the number of puncture attempts and spinal procedure time and increasing the success rate. We hypothesized that ultrasound can facilitate neuraxial blockade, particularly in pregnant women with difficult topographic anatomy.

METHODS

One hundred (50 lean, BMI <30 kg/m(2), and 50 obese, BMI ≥30 kg/m(2)) parturients scheduled for cesarean delivery were divided into ultrasound and control groups. Subarachnoid block was performed with prepuncture ultrasound examination in lean parturients (group 1, n = 25) and in obese parturients (group 2, n = 25), and subarachnoid block was performed without prepuncture ultrasound examination in lean parturients (group 3, n = 25) and in obese parturients (group 4, n = 25). The number of puncture attempts and puncture levels were recorded.

RESULTS

A lower number of puncture attempts and fewer puncture levels were detected in ultrasound (US) groups (p < 0.001). First attempt success rate under US guidance was 92 % in comparison to 44 % using a conventional technique in obese parturients (p < 0.001). In 52 % of the lean patients and in 54.2 % of the obese patients, the intercristal line was at the L3-L4 and at the L2-L3 interspace, respectively. The duration of spinal procedure was shorter in US groups (22 vs. 52 s, p = 0.031). We found a high correlation between ultrasound and needle depth (r = 0.709, p < 0.001).

CONCLUSIONS

We found a high level of success in the prepuncture ultrasound-determined insertion point. The ultrasound imaging technique can be a reliable guide to facilitate spinal anesthesia, especially in obese parturients.

Ultrasound assessment of the vertebral level of the intercristal line in pregnancy

BACKGROUND

The intercristal line is known to most frequently cross the L4 spinous process or L4-5 interspace; however, it is speculated to be positioned higher during pregnancy because of the exaggerated lumbar lordosis. Clinical estimation of vertebral levels relying on the use of the intercristal line has been shown to often be inaccurate. We hypothesized that the vertebral level of the intercristal line determined by palpation would be higher than the level determined by ultrasound in pregnant women.

METHODS

Fifty-one term pregnant patients were recruited. Two experienced anesthesiologists performed estimates of the position of the intercristal line by palpation. Using ultrasound, another anesthesiologist who was blinded to the clinical estimates, determined the position of the superior border of the iliac crest in the transverse and longitudinal planes and then identified the lumbar vertebral levels. The vertebral level at which the clinical estimates of the intercristal line crossed the spine was recorded and compared with the ultrasound-determined level of the superior border of the iliac crest.

RESULTS

The clinical estimates of the spinal level of the intercristal line agreed with the ultrasound measurement 14% of the time (14 of 101; 95% confidence interval [CI]: 8%, 22%). The clinical estimates were 1 level higher than the ultrasound measurement 23% of the time (23 of 101; 95% CI: 16%, 32%) and >1 level higher 25% of the time (25 of 101; 1-tailed 95% CI: >18%). The distribution of the clinical estimates found clinicians locating the intercristal line at L3 or L3-4 54% of the time (54 of 101; 95% CI: 44%, 63%) and at L2-3 or higher 27% of the time (27 of 101; 1-tailed 95% CI: >20%).

CONCLUSION

The anatomical position of the intercristal line was at L3 or higher in at least 6% of term pregnant patients using ultrasound. Clinical estimates were found to be ≥1 vertebral level higher than the anatomical position determined by ultrasound at least 40% of the time. This disparity may contribute to misidentification of lumbar interspaces and increased risk of neurologic injury during neuraxial anesthesia.

Palpatory accuracy of lumbar spinous processes using multiple bony landmarks

OBJECTIVE

Accurate localization of vertebral segments is crucial for many treatment procedures. The objective of this study was to determine accuracy of identification of lumbar spinous process levels by palpation.

METHODS

Three examiners independently identified the spinous processes of L1-L4 on 60 prone volunteers using multiple bony landmarks including the sacral base, L5, Tuffier's line, T12, and the 12th ribs. The spinous processes were marked with radiopaque skin markers. Location of marker placement and presence of anatomical anomalies were determined by posteroanterior lumbar radiographs. Accuracy of marker placement and interobserver reliability were assessed using weighted κ values. Generalized linear mixed models and Cochran-Mantel-Haenszel tests assessed the relationship of accuracy to training level, presence of anatomical anomalies, and participant characteristics.

RESULTS

Examiners identified a spinous process in 91% of vertebral assessments. Correct identification of vertebral level occurred 69% of the time (κ = 0.81; 95% confidence interval, 0.79-0.83). Faculty examiners were significantly more accurate in identifying the correct vertebral level than the resident examiner (67%-78% vs 51%, P ≤ .03). The presence of 12th rib anomalies decreased accuracy for all examiners (P ≤ .05), reducing accuracy from 74% to 55%. Accuracy was higher in male participants than in female participants (P = .01). Obesity significantly decreased accuracy (P = .0003) at L3 (50% vs 73%) and L4 (44% vs 72%).

CONCLUSIONS

Identification of lumbar spinous processes using multiple landmarks was more accurate than previously reported values. However, accuracy was dependent on examiner experience, presence of anatomical anomalies, and participant characteristics.

Can parturients identify the midline during neuraxial block placement?

STUDY OBJECTIVE

To determine whether parturients can reliably identify their midline during epidural or spinal needle insertion, and to determine whether parturient feedback helps the anesthesiologist successfully identify the midline.

DESIGN

Survey instrument completed by anesthesiologists.

SETTING

Labor and delivery unit of a university-based, tertiary-care hospital.

MEASUREMENTS

Completed questionnaires were obtained for 554 of 904 (61.3%) neuraxial blocks. Data were collected on the type of neuraxial block, number of needle redirections required to identify the midline, the patient's height and weight, the patient's position during block placement, whether the patient was questioned for assistance identifying the midline, and if so, how helpful the patient was in redirecting the needle to locate the epidural or subarachnoid space.

MAIN RESULTS

The anesthesiologist requested the assistance of 194 patients (35.0%) for needle location. Of those questioned, the anesthesiologist reported 128 instances (66.0%) when the patient's response was helpful in identification of the midline. Morbidly obese parturients (BMI > 35 kg/m²) were questioned more often than their non-morbidly obese counterparts (48.9% vs. 30.5%; P < 0.0005). Of those morbidly obese parturients who were questioned (n = 64), 76.6% were reported by the anesthesiologist to be helpful.

CONCLUSIONS

Most patients, including morbidly obese patients, are helpful in identifying the midline during neuraxial anesthesia.

Ultrasound in obstetric anaesthesia: a review of current applications

Ultrasound equipment is increasingly used by non-radiologists to perform interventional techniques and for diagnostic evaluation. Equipment is becoming more portable and durable, with easier user-interface and software enhancement to improve image quality. While obstetric utilisation of ultrasound for fetal assessment has developed over more than 40years, the same technology has not found a widespread role in obstetric anaesthesia. Within the broader specialty of anaesthesia; vascular access, cardiac imaging and regional anaesthesia are the areas in which ultrasound is becoming increasingly established. In addition to ultrasound for neuraxial blocks, these other clinical applications may be of value in obstetric anaesthesia practice.

Imaging during pregnancy

The use of imaging techniques in women who are pregnant has increased greatly over the past decade. This focused review discusses the risks and indications of ultrasonography, magnetic resonance imaging, computed tomographic scanning, and fluoroscopy for the evaluation of the parturient with non-obstetric disorders. Diagnostic imaging of the pregnant woman for the evaluation of disorders not related to pregnancy is evolving, and protocols will vary from institution to institution. The potential benefit from indicated diagnostic radiological procedures in the parturient nearly always outweighs risk to the fetus because radiation exposure from a single procedure conveys little fetal risk.

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.