Ultrasonography of the lumbar spine for neuraxial and lumbar plexus blocks

Comparison of ultrasonographic anatomy of spine in traditional sitting position versus crossed leg position in term pregnancy: A prospective, observational, crossover study

Background and Aims

The traditional sitting position (TSP) and crossed leg sitting position (CLSP) are positions used for neuraxial anaesthesia. This study compared the interspinous space (ISS) distance using ultrasound assessment of the spine in these positions in parturients in term gestation.

Methods

This prospective, observational study involved ultrasonographic spine assessment in 100 parturients in term gestation with them in either TSP or CLSP. The median sagittal view measured the crescent-shaped hyperechoic reflections of the spinous processes and ISSs in L3-L4, L4-L5 and L5-S1 levels. The paramedian sagittal oblique view showed interlaminar spaces (ILSs). Paired t-test and Chi-square test were used for continuous and categorical variables, respectively.

Results

The ISS distance (cm) increased in CLSP compared to TSP at levels L3-L4 (1.44 [0.34] [1.34-1.54] versus 1.22 [0.30] [1.12-1.32], P = 0.04), L4-L5 (1.34 [0.39] [1.20-1.48] versus 1.14 [0.30] [0.96-1.32], P = 0.01) and L5-S1 (1.28 [0.33] [1.17-1.39] versus 1.18 [0.23] [1.11-1.26], P = 0.02). The ILS distance (cm) increased in CLSP compared to TSP at interspaces L3-L4 (1.27 [0.34] [1.18-1.36] versus 1.12 [0.20] [1.08-1.16], P = 0.001), L4-L5 (1.26 [0.33] [1.17-1.35] versus 1.19 [0.32] [1.12-1.26], P = 0.01) and L5-S1 (1.28 [0.33] [1.18-1.38] versus 1.16 [0.27] [1.09-1.23], P = 0.001).

Conclusion

Crossed leg sitting position for neuraxial anaesthesia in term pregnancy results in more widening of both interspinous and interlaminar spaces compared to traditional sitting position.

Visceral versus somatic pain: an educational review of anatomy and clinical implications

Somatic and visceral nociceptive signals travel via different pathways to reach the spinal cord. Additionally, signals regulating visceral blood flow and gastrointestinal tract (GIT) motility travel via efferent sympathetic nerves. To offer optimal pain relief and increase GIT motility and blood flow, we should interfere with all these pathways. These include the afferent nerves that travel with the sympathetic trunks, the somatic fibers that innervate the abdominal wall and part of the parietal peritoneum, and the sympathetic efferent fibers. All somatic and visceral afferent neural and sympathetic efferent pathways are effectively blocked by appropriately placed segmental thoracic epidural blocks (TEBs), whereas well-placed truncal fascial plane blocks evidently do not consistently block the afferent visceral neural pathways nor the sympathetic efferent nerves. It is generally accepted that it would be beneficial to counter the effects of the stress response on the GIT, therefore most enhanced recovery after surgery protocols involve TEB. The TEB failure rate, however, can be high, enticing practitioners to resort to truncal fascial plane blocks. In this educational article, we discuss the differences between visceral and somatic pain, their management and the clinical implications of these differences.

Dural sac cross-sectional area is a highly effective parameter for spinal anesthesia in geriatric patients undergoing transurethral resection of the prostate: a prospective, double blinded, randomized study

Background

Spinal anesthesia is optimal choice for transurethral resection of the prostate (TURP), but the sensory block should not cross the T10 level. With advancing age, the sensory blockade level increases after spinal injection in some patients with spinal canal stenosis. We optimize the dose of spinal anesthesia according to the decreased ratio of the dural sac cross-sectional area (DSCSA), the purpose of this study is to hypothesis that if DSCSA is an effective parameter to modify the dosage of spinal anesthetics to achieve a T10 blockade in geriatric patients undergoing TURP.

Methods

Sixty geriatric patients schedule for TURP surgery were enrolled in this study. All subjects were randomized divided into two groups, the ultrasound (group U) and the control (group C) groups, patient receive either a dose of 2 ml of 0.5% isobaric bupivacaine in group C, or a modified dose of 0.5% isobaric bupivacaine in group U. We measured the sagittal anteroposterior diameter (D) of the dural sac at the L3–4 level with ultrasound, and calculated the approximate DSCSA (A) according to the following formula: A = π(D/2)², ( π = 3.14). The modified dosage of bupivacaine was adjusted according to the decreased ratio of the DSCSA.

Results

The cephalad spread of the sensory blockade level was significantly lower (P < 0.001) in group U (T10, range T7–T12) compared with group C (T3, range T2–T9). The dosage of bupivacaine was significantly decreased in group U compared with group C (P < 0.001). The regression times of the two segments were delay in group U compared with group C (P < 0.001). The maximal decrease in MAP was significantly higher in the group C than in group U after spinal injection (P < 0.001), without any modifications HR in either group. Eight patients in group C and two patients in group U required ephedrine (P = 0.038).

Conclusions

The DSCSA is a highly effective parameter for spinal anesthesia in geriatric patients undergoing TURP, a modified dose of local anesthetic is a critical factor for controlling the sensory level.

Trial registration

This study was registered in the Chinese Clinical Trial Registry (Registration number: ChiCTR1800015566).on 8, April, 2018.

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.

Sonography guided lumbar nerve and facet blocks: The first report of clinical outcome from Iran

INTRODUCTION

Nerve root block (NRB) and facet block (FB) are viable options for pain arising from facet and lumbar disc herniation (LDH) not responding to conservative therapy but still not suitable for surgery. Classically, they are performed under fluoroscopy and computed tomography (CT) guidance, which have the disadvantages of radiation exposure and limited accessibility. The aim of this study was to assess the effectiveness of US guided FB and NRB in patients suffering from facet arthropathy and LDH.

METHODS

14 patients were involved in the study. After defining nerve root (for NRB) or facet joints (for FB) under a standard US investigation, real-time injection of methylprednisolone and bupivacaine was performed. Pain was measured before and after procedure by VAS.

RESULTS

Ten patients underwent FBs (8 bilateral and 2 unilateral) and 4 underwent NRBs (2 bilateral and 2 unilateral). 11/14 (79%) patients improved after the block (8 in FB, 3 in NRB) and the VAS had significantly decreased 1 week after procedure (mean [range] -1.7 [-6 to 0]). For the 11 patients that improved after FB or NRB, the effect lasted for a mean of 59 days (range: 30-130 days). Analysis showed that neither block procedure (NRB vs. FB) nor block level (L4L5 vs. L5S1) had an effect on result.

CONCLUSIONS

Results of our preliminary study shows that in appropriately selected patients, nerve root and facet blocks can be effectively performed under ultrasonography guidance without notable complications, with effects lasting for a mean 2 months.

Modern approach to an old technique: Narrative revision of techniques used to locate the epidural space

Since the first description of the epidural technique during the 1920s, the continuous progress of knowledge of the anatomy and physiology of the epidural space has allowed the development of different techniques to locate this space while increasing both the safety and efficacy of the procedure. The most common techniques used today are based on the two main characteristics of the epidural space: the difference in distensibility between the ligamentum flavum and the epidural space, and the existence of negative pressure within the epidural space. However, over recent years, technological advances have allowed the development of new techniques to locate the epidural space based on other physical properties of tissues. Some are still in the experimental phase, but others, like ultrasound-location have reached a clinical phase and are being used increasingly in daily practice.

Spinal ultrasound versus palpation for epidural catheter insertion in labour: A randomised controlled trial

BACKGROUND

Ultrasound imaging of the spine is thought to reduce failed and traumatic neuraxial procedures. Most of the evidence supporting this assumption has been produced in the context of an expert sonographer performing the ultrasound assessment, and it remains unknown whether this technique is useful when used by multiple individual operators.

OBJECTIVE

To invesstigate the impact of preprocedural spinal ultrasound on the ease of insertion of labour epidurals by a group of trainees. We hypothesised that the ultrasound-assisted technique would improve the ease of insertion when compared with the conventional palpation technique.

DESIGN

A randomised controlled trial.

SETTING

Academic hospital in Toronto, Canada.

PARTICIPANTS AND INTERVENTION

A group of 17 second-year anaesthesia residents and five anaesthesia fellows underwent a training programme in ultrasound assessment of the spine. Parturients with easily palpable lumbar spines were randomised to either ultrasound or palpation group. Residents and fellows performed both the assessment (ultrasound or palpation) and the epidural procedure.

MAIN OUTCOME MEASURES

PRIMARY OUTCOME

ease of insertion of epidural catheter composed of the time taken to insert the epidural catheter, number of interspace levels attempted and number of needle passes.

SECONDARY OUTCOMES

total procedural time (assessment and insertion); first pass success rate; number of attempts required to thread the epidural catheter; failure of epidural analgesia; and patient satisfaction.

RESULTS

We analysed 128 epidural catheter insertions (residents 84, fellows 44). There was no difference in median (interquartile range, IQR) epidural insertion time between the ultrasound and palpation groups [174 (120 to 241) versus 180 (130 to 322.5) s, respectively; P = 0.14]. The number of interspace levels attempted and needle passes were also similar in both groups. The total procedural time was longer in the ultrasound group.

CONCLUSION

The use of preprocedural spinal ultrasound by a cohort of anaesthesia trainees did not improve the ease of insertion of labour epidural catheters in patients with easily palpable lumbar spines, as compared with the traditional palpation technique based on anatomical landmarks.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00996905.

Real-time ultrasound-guided comparison of adductor canal block and psoas compartment block combined with sciatic nerve block in laparoscopic knee surgeries

Background:

Lumbar plexus block, combined with a sciatic nerve block, is an effective locoregional anesthetic technique for analgesia and anesthesia of the lower extremity. The aim of this study was to compare the clinical results outcome of the adductor canal block versus the psoas compartment block combined with sciatic nerve block using real time ultrasound guidance in patients undergoing elective laparoscopic knee surgeries.

Patients and Methods:

Ninety patients who were undergoing elective laparoscopic knee surgeries were randomly allocated to receive a sciatic nerve block in addition to lumbar plexus block using either an adductor canal block (ACB) or a posterior psoas compartment approach (PCB) using 25 ml of bupivacine 0.5% with adrenaline 1:400,000 injection over 2-3 minutes while observing the distribution of the local anesthetic in real time. Successful nerve block was defined as a complete loss of pinprick sensation in the region that is supplied by the three nerves along with adequate motor block, 30 minutes after injection. The degree of motor block was evaluated 30 minutes after the block procedure. The results of the present study showed that the real time ultrasound guidance of PCB is more effective than ACB approach. Although the sensory blockade of the femoral nerve achieved equally by both techniques, the LFC and OBT nerves were faster and more effectively blocked with PCB technique. Also PCB group showed significant complete sensory block without need for general anesthesia, significant decrease in the post-operative VAS and significant increase time of first analgesic requirement as compared to the ACB group.

Result and Conclusion:

The present study demonstrates that blockade of lumber plexus by psoas compartment block is more effective in complete sensory block without general anesthesia supplementation in addition to decrease post-operative analgesic requirement than adductor canal block.

Lumbar Ultrasound Image Feature Extraction and Classification with Support Vector Machine

Needle entry site localization remains a challenge for procedures that involve lumbar puncture, for example, epidural anesthesia. To solve the problem, we have developed an image classification algorithm that can automatically identify the bone/interspinous region for ultrasound images obtained from lumbar spine of pregnant patients in the transverse plane. The proposed algorithm consists of feature extraction, feature selection and machine learning procedures. A set of features, including matching values, positions and the appearance of black pixels within pre-defined windows along the midline, were extracted from the ultrasound images using template matching and midline detection methods. A support vector machine was then used to classify the bone images and interspinous images. The support vector machine model was trained with 1,040 images from 26 pregnant subjects and tested on 800 images from a separate set of 20 pregnant patients. A success rate of 95.0% on training set and 93.2% on test set was achieved with the proposed method. The trained support vector machine model was further tested on 46 off-line collected videos, and successfully identified the proper needle insertion site (interspinous region) in 45 of the cases. Therefore, the proposed method is able to process the ultrasound images of lumbar spine in an automatic manner, so as to facilitate the anesthetists' work of identifying the needle entry site.

Lumbar plexus block surface landmarks as assessed by computed axial tomography in adult patients with scoliosis: a case series

BACKGROUND AND OBJECTIVES

Lumbar plexus (LP) block is a common and useful regional anesthesia technique. Surface landmarks used to identify the LP in patients with healthy spines have been previously described, with the distance from the spinous process (SP) to the skin overlying the LP being approximately two-thirds the distance from the SP to the posterior superior iliac spine (PSIS) (SP-LP:SP-PSIS ratio). In scoliotic patients, rotation of the central neuraxis may make these surface landmarks unreliable, possibly leading to an increased block failure rate and an increased incidence of complications. The objective of the present study was to describe these surface landmarks of the LP in patients with scoliosis.

METHODS

We selected 47 patients with known thoracolumbar scoliotic disease from our institution's radiology archives. We measured bony landmark geometry, Cobb angle, and the LP location and depth. Additionally, we calculated the SP-LP:SP-PSIS ratio for both the concave and convex sides.

RESULTS

In scoliotic patients (31 females and 16 males), the median (range) Cobb angle was 23 (8-54) degrees. The LP depth was 7.5 (5.7-10.7) cm on the concave side of the scoliotic spine and 7.6 (5.4-10.8) cm on the convex side, while the distance from the SP-LP was 3.4 (1.9-4.7) cm on the concave side and 3.7 (2.4-5.1) cm on the convex side. The SP-LP:SP-PSIS ratio was 0.61 (0.20-0.97) and 0.65 (0.45-0.98) on the concave and convex sides, respectively. None of these distances were significantly different between sides.

CONCLUSIONS

In patients with scoliotic disease of the spine, there is wide variability in the bony surface landmarks. The location of the LP is generally more medial than expected when compared with both modified and traditional landmarks. A review of the imaging studies and the pre-procedural ultrasound assessment of the anatomy should be considered prior to needle puncture.

Evidence-based medicine for ultrasound-guided regional anesthesia

Available evidence favoring the use of ultrasound for regional anesthesia is reviewed, updated, and critically assessed. Important outcome advantages include decreased time to block onset; decreased risk of local anesthetic systemic toxicity; and, depending on the outcome definition, increased block success rates. Ultrasound guidance, peripheral nerve blocks, and central neuraxial blocks are discussed.

Factors associated with difficult neuraxial blockade

Spinal and epidural blocks are common practice in anesthesia and are usually used for various surgical or endoscopic procedures. Correct identification and puncture of the epidural or subarachnoid space determine the success or failure of the technique. Multiple attempts and difficult access to the epidural or subarachnoid space is a frequent problem in operating theaters and may be hazardous due to a number of possible acute or long-term complications. In addition, multiple punctures are associated with increased pain and patient discomfort. The aim of this study was to determine the factors associated with a difficult spinal or epidural block, dependent on the patient (age, gender, height, weight, body mass index, and quality of anatomical landmarks), the technique (type of blockade, needle gauge, and patient positioning), and the provider (level of experience). The study was conducted at the Department of Anesthesiology, Resuscitation, and Intensive Care Unit of University Hospital Osijek (Osijek, Croatia) and it included 316 patients who underwent a range of different surgical procedures in neuraxial blocks. There were 219 cases of first puncture success, while the overall success of neuraxial blocks was 97.5%. Five patients (1.6%) were submitted to the alternative technique, ie, general anesthesia. In three patients (0.9%), neuraxial block was partial so they required supplementation of intravenous anesthetics and analgesics. Furthermore, it was found that first puncture success was associated with younger age (P=0.007), lower weight (P=0.032), and body mass index (P=0.020). Spine deformity (P=0.015), poor identification of interspinous space (P=0.005), recumbent patient position during the puncture (P=0.001), and use of a paramedian approach were associated with first puncture failure. Adequate preoperative prediction of difficulties can help to reduce the incidence of multiple attempts, rendering the technique more acceptable and less risky to the patient, and consequently leading to improvement of medical care quality. The attending anesthesiologist should consider an alternative technique (general anesthesia or peripheral nerve block) for a patient if certain difficulties can be predicted.

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.

Use of ultrasound for lower extremity

PURPOSE OF REVIEW

To explore the recent advances in the use of ultrasound for lower extremity blocks, including approaches to the lumbar and sacral plexus blocks.

RECENT FINDINGS

Procedures of the lower extremity often require blocks of the lumbar and sacral plexuses. The use of ultrasound offers some advantages, including the possibility to directly visualize the distribution of local anesthetics.

SUMMARY

Lower extremity blocks under ultrasound guidance often require advanced skills because of the depth of target nerves. This review summarizes the recent advances in the use of ultrasound guidance over traditional techniques.

Ultrasonography of the lumbar spine: sonoanatomy and practical applications

Ultrasonography of the bones and joints has gained considerable ground in the field of rheumatology over the past decade and is now used in everyday practice both for diagnostic purposes and to guide local injections. However, the use of ultrasonography is virtually confined to the peripheral joints, whereas spinal diseases make a major contribution to rheumatology practice. Studies have established that ultrasonography of the lumbar spine is feasible. Adequate equipment and familiarity with spinal sonoanatomy are required. In this update, we suggest starting with a systematic examination of the lumbar spine to assess the various anatomic structures, from the thoracolumbar fascia superficially to the posterior part of the vertebras at the deepest level. The ligaments, erector spinae muscles, facet joints, and transverse processes can be visualized. Ultrasonography can serve to guide injections into the facet joints, about the nerve roots, and into the iliolumbar ligaments; as well as to identify relevant landmarks before epidural injection. Although diagnostic applications are more limited at present, systematic studies of abnormal ultrasonography findings will allow evaluations of the potential usefulness of ultrasonography for diagnosing spinal disorders. The depth of the spinal structures limits the ability to obtain high-resolution images. However, future technical improvements in ultrasound transducers and machines, together with the growing number of physicians trained in ultrasonography, can be expected to benefit the development of spinal ultrasonography in the near future.

Ultrasound for the anesthesiologists: present and future

Ultrasound is a safe, portable, relatively inexpensive, and easily accessible imaging modality, making it a useful diagnostic and monitoring tool in medicine. Anesthesiologists encounter a variety of emergent situations and may benefit from the application of such a rapid and accurate diagnostic tool in their routine practice. This paper reviews current and potential applications of ultrasound in anesthesiology in order to encourage anesthesiologists to learn and use this useful tool as an adjunct to physical examination. Ultrasound-guided peripheral nerve blockade and vascular access represent the most popular ultrasound applications in anesthesiology. Ultrasound has recently started to substitute for CT scans and fluoroscopy in many pain treatment procedures. Although the application of airway ultrasound is still limited, it has a promising future. Lung ultrasound is a well-established field in point-of-care medicine, and it could have a great impact if utilized in our ORs, as it may help in rapid and accurate diagnosis in many emergent situations. Optic nerve sheath diameter (ONSD) measurement and transcranial color coded duplex (TCCD) are relatively new neuroimaging modalities, which assess intracranial pressure and cerebral blood flow. Gastric ultrasound can be used for assessment of gastric content and diagnosis of full stomach. Focused transthoracic (TTE) and transesophageal (TEE) echocardiography facilitate the assessment of left and right ventricular function, cardiac valve abnormalities, and volume status as well as guiding cardiac resuscitation. Thus, there are multiple potential areas where ultrasound can play a significant role in guiding otherwise blind and invasive interventions, diagnosing critical conditions, and assessing for possible anatomic variations that may lead to plan modification. We suggest that ultrasound training should be part of any anesthesiology training program curriculum.