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Description and evaluation of four ultrasound-guided approaches to aid spinal canal puncture in dogs
Abstract
Objective
To describe four ultrasound-guided approaches to the lumbar and thoracic spine to aid spinal canal puncture in the dog and to evaluate the feasibility of the technique. Study designProspective experimental study. Animal populationTwo canine cadavers. Methods
In the first part of the study, the ultrasonographic appearance of the interlaminar space in the lumbosacral, lumbar and thoracic regions was described. In the second part of the study, four operators attempted a real-time, ultrasound-guided approach to the vertebral canal. Each operator performed the technique 20 times in total: five times at the lumbosacral junction, five in the thoracic region, five in the lumbar region with an in-plane approach, and five in the lumbar region with an out-of-plane approach. Computed tomography (CT) was used to confirm the position of the needle. The procedure was considered successful when the tip of the needle was observed within the vertebral canal. The success rate was calculated for each approach and operator. Fisher's exact test was used to compare differences between approaches and operators. ResultsIn all cases, visualization of a ventral, parallel and straight hyperechoic line (floor of the vertebral canal) was considered a necessary prerequisite for successful positioning of the needle within the vertebral canal. A straight hyperechoic line (ligamentum flavum or dura mater) closer to the ultrasound probe was visualized in both the median lumbosacral approach and the transverse lumbar approach. The success rate overall was 81%; for the lumbosacral approach, 100%; for the thoracic approach, 80%; for the in-plane lumbar approach 95%; and for the out-of-plane lumbar approach, 45%. These differences were statistically significant (p<0.001). Conclusions and clinical relevanceThe sonographic description of these approaches was considered adequate for performing spinal canal puncture. In-plane techniques achieved a higher success rate than out-of-plane ones. Further studies are needed to evaluate them in a clinical setting.
... In veterinary and human medicine, ultrasonography is commonly used to perform peripheral nerve blocks and it is becoming more and more popular as an adjunct method for anesthesia of the spinal nerves [9][10][11][12][13][14][15]. There are reports of ultrasound-guided cerebrospinal fluid collection, epidural catheter placement, and epidural puncture [16][17][18][19][20][21][22][23]. ...
Ultrasound is an imaging technique commonly used in veterinary medicine. Ultrasound devices are widely available, their means of examination are relatively short and cheap, and they do not generate ionizing radiation. In addition, ultrasound generally does not need to be performed under general anesthesia. This study was performed on 23 canine cadavers with full clinical histories and with no confirmed pathological changes in the spine region. The imaging modalities were established in dogs in lateral recumbency, with the selected side being the uppermost angle, in a neutral position. All dogs were examined in the transverse and longitudinal planes. Sacral crest, intertransverse ligament, vertebral canal floor, vertebral body, and intervertebral discs were only visible in the longitudinal plane. Vertebral arch, supraspinal ligament, dorsal wall of the vertebral canal and muscles were visualized only in the transverse plane. This article provides a brief and relatively easy-to-perform protocol for ultrasound imaging of the lumbar spine of dogs. In addition, it presents a detailed description of the sonoanatomy of the area under investigation.
... Tot slot kan door de aanwezigheid van vet soms een vals gevoel van weerstandsverlies ervaard worden, waardoor men foutief denkt dat de naald reeds in de epidurale ruimte is. Om het succespercentage te verhogen, kan controle via echografie gebruikt worden bij het uitvoeren van epidurale en spinale anesthesie (Ingrande et al., 2009;Viscasillas et al., 2016). ...
Previous study demonstrated decreased allergenicity in vitro of some food allergens after conjugation with polyphenols. However, little is known about how polyphenol conjugation with food allergens affects in vivo allergenicity. We conjugated a well-known food allergen, ovalbumin (OVA), with quercetin (QUE) to assess the potential allergenicity of OVA in vitro and in vivo in a BALB/c mouse model. QUE could covalently conjugate with OVA and changed the protein structure, which might destroy and/or mask OVA epitopes. Conjugation with QUE decreased IgE-binding properties and the release capacity of the conjugates. In vivo, as compared with native protein, conjugation with QUE decreased the levels of IgE, IgG1, IgG, plasma histamine and mast cell protease-1 (mMCP-1) on the surface of sensitized mast cells, along with decreased FcεRI+ and c-kit+ expression. The levels of Th2-related cytokines (IL-4, IL-5, IL-13) were decreased and that of a Th1-related cytokine (IFN-γ) was increased slightly, which suggests that conjugation with QUE modulated the imbalance of the Th1/Th2 immune response. Conjugation of OVA with QUE could reduce OVA allergenicity in vitro and in vivo, which could provide information for reducing food allergenicity by conjugation with polyphenols.
... Tot slot kan door de aanwezigheid van vet soms een vals gevoel van weerstandsverlies ervaard worden, waardoor men foutief denkt dat de naald reeds in de epidurale ruimte is. Om het succespercentage te verhogen, kan controle via echografie gebruikt worden bij het uitvoeren van epidurale en spinale anesthesie (Ingrande et al., 2009;Viscasillas et al., 2016). ...
Obesitas is een belangrijk probleem in de diergeneeskunde. Aangezien obesitas niet enkel een opstapeling van vet is maar ook belangrijke cardiovasculaire en respiratoire implicaties heeft, kan dit het verloop van de anesthesie sterk beïnvloeden bij de betrokken patiënten. Bovendien kan obesitas een onderliggende oorzaak hebben of leiden tot gerelateerde aandoeningen die op hun beurt de anesthesie compliceren. Tot slot leidt obesitas ook tot veranderingen in de farmacokinetiek en -dynamiek, van onder andere anesthetica. Deze veranderingen vereisen dosisaanpassingen, afhankelijk van het anestheticum. In de diergeneeskunde is de beschikbare informatie hierover echter zeer beperkt en wordt ze daarom grotendeels verkregen door extrapolatie uit de humane geneeskunde. In dit artikel wordt een overzicht gegeven van de pathofysiologische en farmacologische veranderingen bij obese dieren waarmee rekening gehouden moet worden tijdens de anesthesie.
Correctly identifying the puncture site and needle position in obese dogs can be challenging to achieve epidural anaesthesia. The current study aimed to evaluate a real-time ultrasound-guided technique, to perform epidural anaesthesia in obese or appropriate body condition score dogs, based on visualization of local anaesthetic flow during its injection, compared to the traditional method of palpation of anatomical landmarks. Seventy-two client-owned dogs were evaluated in a prospective, comparative, randomized clinical trial, allocated into four groups of 18 dogs. For the Palpation-guided 1 (PG1) and 2 (PG2) groups, epidural anaesthesia was based on palpating anatomical landmarks. Dogs with a body condition score (BCS) 1-5/9 were included in the PG1 (non-obese), and those with a BCS 6-9/9 in PG2 (obese) groups. In the Ultrasound-guided 1 (USG1 - BCS 1-5/9) and 2 (USG2 – BCS 6-9/9) groups, epidural anaesthesia was guided by ultrasound (US).
The flow of anaesthetic through the epidural canal was observed in all dogs by US. There were fewer needle-to-bone contacts in the US-guided groups when performing epidural anaesthesia; this only occurred on the vertebral laminae, never in the vertebral canal. Ultrasound guidance enabled local anaesthetic injection into the epidural space without the need for palpation of anatomical landmarks to guide needle placement. Blood reflux occurred in 11.1% (PG1), 22.2% (PG2), 5.5% (USG1), and 0% (USG2) of the dogs. Ultrasound-guided punctures led to fewer vascular punctures. Epidural anaesthesia was effective in all animals, and no complications were observed.
Ultrasound allows differentiation of the bony structures and the contents of the spinal canal, such as ligaments, meninges, spinal cord, and nerve roots. Additionally, it is useful to determine the path and depth of needle introduction. This chapter identifies regional anatomy of the vertebral column and also identifies the contents of the spinal canal. In order to obtain an adequate ultrasound image of the vertebral canal, the ultrasound beam needs to reach the vertebral canal from dorsal to ventral, regardless of the probe position. This approach allows the identification of two parallel hyperechoic (bright white) lines flanked by an acoustic shadow produced by the high impedance of the surrounding bones. A longitudinal ultrasound scan of the vertebral column allows identification of the intervertebral level and direction of the needle when an in‐plane neuraxial blockade is performed.
During minimally invasive spinal surgery, correct identification of the affected intervertebral disc space is critical. Percutaneous palpation is commonly used, but results may be unreliable. Fluoroscopy is the gold standard but can be cumbersome and exposes operators to ionizing radiation. Spinal ultrasound has been described in veterinary medicine and could be a feasible alternative. This prospective, methods comparison study mimicked a minimally invasive spinal surgery in 10 canine cadavers and compared the accuracy of ultrasound and percutaneous palpation for thoracolumbar intervertebral disc space identification, using fluoroscopy as the reference standard. For each experiment, a disc space was randomly chosen. Identification was then attempted using both percutaneous palpation and ultrasound. For ultrasound, a linear probe was used to guide the operator to the correct location. The time necessary to perform each method was recorded. Accuracies for each method were calculated and statistically compared. Effects of body condition score, location of the targeted thoracolumbar intervertebral disc space and learning curve for each method were also evaluated. Ultrasonographic identification was more accurate (96.7% vs. 76.7%; P < 0.03) but took longer (147 s vs. 29 s; P < 0.0001) than percutaneous palpation. Findings from this cadaver study indicated that percutaneous palpation alone had low accuracy for correctly identifying a targeted thoracolumbar intervertebral disc space and supported the use of ultrasound as a method for improving the accuracy. Future studies are needed to assess the method in clinical cases, especially in obese dogs and/or those in which the targeted site is distant from palpable anatomical landmarks.
Objective:
To examine the effect of sternal or lateral recumbency, with or without cranial extension of the hindlimbs, on the distance between the dorsal lumbosacral laminae in dogs.
Study design:
Blinded, randomized, crossover, experimental study.
Animals:
A total of 19 canine cadavers.
Methods:
Computed tomography of the lumbosacral junction was performed in four positions: sternal and right lateral recumbency, with hindlimbs extended cranially or not. Order of positioning was randomized. The lumbosacral interlaminar (LSI) distance, defined as the distance between the dorsal laminae of the seventh lumbar vertebra (caudal margin) and sacrum (cranial margin), was measured for each position by two independent assessors who were unaware of positioning. Mean distances in each position were compared using a paired t-test, corrected for multiple comparisons.
Results:
For n = 19 cadavers [6 female; median (range) age 9 (0.3-16) years; weight, 20.4 (1.0-34.0) kg], cranial extension of the hindlimbs increased the LSI distance, compared with control, in both sternal (9.2 ± 2.2 mm versus 3.1 ± 1.3 mm, p < 0.001) and right lateral recumbency (8.2 ± 1.9 mm versus 4.9 ± 1.5 mm, p < 0.001). With the hindlimbs extended cranially, sternal recumbency increased LSI distance when compared with right lateral recumbency (p < 0.001).
Conclusions and clinical relevance:
Cranial extension of the hindlimbs in both sternal and lateral recumbency increases the LSI distance to an extent that is both statistically significant and of potential clinical relevance. Although ease of epidural access or injection was not assessed, the small (1 mm) difference in LSI distance between cranial hindlimb extension in sternal and right lateral recumbency is unlikely to be of clinical relevance. Conversely, cranial extension of the hindlimbs in either sternal or lateral recumbency would be expected to facilitate epidural injection.
Objective:
To describe the ultrasound (US) evaluation of the cervical, thoracic and lumbar spinal tracts in piglets and to evaluate the feasibility of the ultrasound guided spinal catheter placement in newborn and paediatric piglets.
Study design:
Prospective experimental study.
Animals:
A total of two piglet cadavers (age, 7 and 14 days) and eight commercial crossbreed piglets divided into four groups according to age: 7 (P7), 14 (P14), 21 (P21) and 28 (P28) days.
Methods:
In the first part of the study an ultrasound examination of the spinal tract was performed in piglet cadavers applying the transverse and the longitudinal approaches in sternal and lateral recumbencies. In the second phase, the piglets were anaesthetized with sevoflurane. A US examination with a 10 MHz linear probe was performed and a spinal catheter was introduced between the spinous processes of L2 and L3 lumbar vertebrae using an in-plane technique and its advancement was monitored with the probe. At the end of procedure, the catheter was removed. The piglets recovered from anaesthesia and were monitored for one week.
Results:
In phase I the authors identified the paramedian longitudinal approach as the most feasible for spinal structure evaluation in piglets. In phase II, the paramedian longitudinal views enabled a good visualization of the spinal cord and of the catheter advancement up to the cisterna magna in groups P7 and P14. In groups P21 and P28 it was not possible to visualize the neuroaxial structures and the spinal catheter using the same approach. No clinical alterations were recorded during the procedure or the following days.
Conclusions and clinical relevance:
US-guided spinal catheter placement appeared a feasible technique in piglets younger than 14 days but it is not useful in older piglets.
Objectives:
To review the methods for verifying the needle position while performing epidural anaesthesia in dogs, and to discuss the advantages, disadvantages, usefulness and reliability of each technique in the experimental and clinical research setting.
Databases used:
PubMed, Scopus, Google Scholar and the Basel University Library online catalogues; the latter, which was provided by the University of Berne, were used as databases. The results were filtered manually based on the titles and abstracts in order to narrow the field.
Conclusions:
Besides some drawbacks, including the potential side effects of contrast medium injection, which may limit its routine use in clinical patients, epidurography should still be regarded as one of the most reliable techniques to verify needle position in dogs. Ultrasonography, electrical nerve stimulation, loss of resistance and the hanging drop technique are regarded as less invasive than epidurography and, for this reason, their use may be more applicable to clinical patients. However, these methods have been described in only a few published reports, all of which involved a limited number of dogs. Finally, the detection of epidural pressure waves has been investigated more extensively in dogs, and the findings of these studies suggest that this technique may be used to verify epidural needle placement for experimental and clinical research, on condition that all the negative subjects are excluded from the study.
There are many advantages to the use of ultrasound in interventional pain medicine procedures. Ultrasound technology is currently
growing exponentially due to its many advantages of improved and real-time high-resolution ultrasound imaging that results
in successful pain management interventions. In addition, use of ultrasound for interventional pain management procedures
avoids the many risks associated with radiation exposure to both the patient and practitioner.
Die Periduralanästhesie (PDA) ist heute das wichtigste geburtshilfliche Analgesieverfahren. Sie wird durch schwangerschaftsbedingte Bindegewebsveränderungen erschwert, die u. a. einen verfrühten “loss of resistance” vortäuschen können. Diagnostische Maßnahmen vor der PDA beschränken sich derzeit auf Inspektion und Palpation. Eine Etablierung diagnostischer Hilfsmittel ist anzustreben. Vor der Anlage einer geburtshilflichen Periduralanästhesie wurde bei 100 Schwangeren prospektiv eine Ultraschalluntersuchung der lumbalen Wirbelsäule durchgeführt. Die Erkennbarkeit aller anatomischen Strukturen wurde bewertet, und die sonographisch gefundenen Entfernungen wurden mit den bei der Punktion vorgefundenen Werten verglichen. Die Korrelation zwischen vor bzw. bei der Punktion gemessenen Werten war mit r2=0,79 hoch. Zwischen Ultraschall- und Punktionswinkel ergab sich jedoch nur eine geringe Abhängigkeit (r2=0,19). Der zeitliche Abstand von Ultraschalluntersuchung und Punktion bedingt eine unvermeidbare Unschärfe: jede Abweichung zwischen Schall- und Punktionsgegebenheiten verursacht Veränderungen der Punktionstiefe. Die Patientenakzeptanz des Verfahrens war sehr gut. Die Ultraschalldiagnostik bietet eine Möglichkeit, Punktionsrichtung und Abstand des Epiduralraums zur Haut noch vor dem Punktionsversuch festzulegen. Die ultraschallgesteuerte PDA für Schwangere lässt sich problemlos in den klinischen Alltag einfügen. Ultraschall kann damit eine wichtige diagnostische Lücke in der Regionalanästhesie füllen.
Die diagnostische Anwendung von Ultraschall mit der Darstellung der Punktionsebene und des Epiduralraumes hat Auswirkungen auf den Ablauf und die Qualität einer Periduralanästhesie.Die vorliegende Arbeit zeigt einen Überblick über die bisherigen Erfahrungen mit Ultraschall im Rahmen der Periduralanästhesie und gibt einen Ausblick auf die Möglichkeiten bildgebender Verfahren in der Regionalanästhesie.Die verschiedenen Arbeitsgruppen, die sich mit Ultraschall und Periduralanästhesie beschäftigen, fanden Korrelationen von 0,79–0,98 zwischen der vorhergesagten und der effektiv gemessenen Punktionstiefe; die Präzision lag zwischen 5,7 mm und 7,7 mm.Die Bestimmung des erwarteten Punktionswinkels ergab eine nur geringe Korrelation zwischen 0,07 und 0,31; die Präzision der gemessenen Werte lag zwischen 10° und 13,4°. In allen Studien konnte eine positive Beeinflussung der Periduralanästhesie durch die Anwendung von Ultraschall im Sinne einer signifikanten Erniedrigung (pppp
Worldwide, the number of overweight and obese patients has increased dramatically. As a result, anesthesiologists routinely encounter obese patients daily in their clinical practice. The use of regional anesthesia is becoming increasingly popular for these patients. When appropriate, a regional anesthetic offers advantages and should be considered in the anesthetic management plan of obese patients. The following is a review of regional anesthesia in obesity, with special consideration of the unique challenges presented to the anesthesiologist by the obese patient.
Recent studies report difficulty in achieving peripheral and neuraxial blockade in obese patients. For example, there is an increased incidence of failed blocks in obese patients compared with similar, normal weight patients. Despite difficulties, regional anesthesia can be used successfully in obese patients, even in the ambulatory surgery setting.
Successful peripheral and neuraxial blockade in obese patients requires an anesthesiologist experienced in regional techniques, and one with the knowledge of the physiologic and pharmacologic differences that are unique to the obese patient.
Current methods of locating the epidural space rely on surface anatomical landmarks and loss-of-resistance (LOR). We are not aware of any data describing real-time ultrasound (US)-guided epidural access in adults.
We evaluated the feasibility of performing real-time US-guided paramedian epidural access with the epidural needle inserted in the plane of the US beam in 15 adults who were undergoing groin or lower limb surgery under an epidural or combined spinal-epidural anaesthesia.
The epidural space was successfully identified in 14 of 15 (93.3%) patients in 1 (1-3) attempt using the technique described. There was a failure to locate the epidural space in one elderly man. In 8 of 15 (53.3%) patients, studied neuraxial changes, that is, anterior displacement of the posterior dura and widening of the posterior epidural space, were seen immediately after entry of the Tuohy needle and expulsion of the pressurized saline from the LOR syringe into the epidural space at the level of needle insertion. Compression of the thecal sac was also seen in two of these patients. There were no inadvertent dural punctures or complications directly related to the technique described. Anaesthesia adequate for surgery developed in all patients after the initial spinal or epidural injection and recovery from the epidural or spinal anaesthesia was also uneventful.
We have demonstrated the successful use of real-time US guidance in combination with LOR to saline for paramedian epidural access with the epidural needle inserted in the plane of the US beam.
Epidural anaesthesia is an important analgesia technique for obstetric delivery. During pregnancy, however, obesity and oedema frequently obscure anatomical landmarks. Using ultrasonography, we investigated the influence of these changes on spinal and epidural anatomy. We examined 53 pregnant women who were to receive epidural block for vaginal delivery or Caesarean section. The first ultrasound imaging was performed immediately before epidural puncture; the follow‐up scan was done 9 months later. The ultrasound scan of the spinal column was performed at the L3/4 interspace in transverse and longitudinal planes, using a Sonoace 6000 ultrasonograph (Kretz®, Marl, Germany) equipped with a 5.0‐MHz curved array probe. We measured two distances from the skin to the epidural space: the minimum (perpendicular) and the maximum (oblique) needle trajectory. The quality of ultrasonic depiction was analysed by a numerical scoring system. An average weight reduction of 12.5 kg had occurred by the follow‐up examination. During pregnancy, the optimum puncture site available on the skin for epidural space cannulation was smaller, the soft‐tissue channel between the spinal processes was narrower, and the skin–epidural space distance was greater. The epidural space was narrower and deformed by the tissue changes. The visibility of the ligamentum flavum, of the dura mater and of the epidural space decreased significantly during pregnancy. Nevertheless, ultrasonography offered useful pre‐puncture information. Thus far, palpation has been the only available technique to facilitate epidural puncture. Ultrasound imaging enabled us to assess the structures to be perforated. We anticipate that this technique will become valuable clinically.
Br J Anaesth 2001; 86: 798–804
Epidural anesthesia may be difficult in pregnancy. We intended to evaluate the teaching possibilities of ultrasonography as a diagnostic approach to the epidural region.
Two groups of residents performed their first 60 obstetric epidurals under supervision. One proceeded in the conventional way using the loss of resistance technique (control group = CG). The other group proceeded in the same way but was supported by prepuncture ultrasound imaging, giving them information about the optimal puncture point, depth and angle (ultrasound group = UG). Success was defined as adequate epidural anesthesia requiring a maximum of three attempts, reaching a visual analogue scale score of less than 1, while neither changing the anesthesia technique, nor starting at another vertebral level. In addition, intervention by the supervisor was defined as failure.
In the CG we observed a success rate of 60% +/- 16% after the first ten attempts followed by a nearly continuous rise of the learning curve. Within the next 50 epidurals the rate of success increased to 84%. In the UG the rate of success started at 86% +/- 15%. Within 50 epidural insertions it rose up to a level of 94%. The difference between the two groups remained significant (P < 0.001).
Using ultrasound imaging for teaching epidural anesthesia in obstetrics we found a higher rate of success during the first 60 attempts compared to conventional teaching. We believe this shows the possible value of ultrasound imaging for teaching and learning obstetric regional anesthesia.
Epidural injections are commonly performed blindly in veterinary medicine. The aims of this study were to describe the lumbosacral ultrasonographic anatomy and to assess the feasibility of an ultrasound-guided epidural injection technique in dogs. A cross sectional anatomic atlas of the lumbosacral region and ex vivo ultrasound images were obtained in two cadavers to describe the ultrasound anatomy and to identify the landmarks. Sixteen normal weight canine cadavers were used to establish two variations of the technique for direct ultrasound-guided injection, using spinal needles or epidural catheters. The technique was finally performed in two normal weight cadavers, in two overweight cadavers and in five live dogs with radiographic abnormalities resulting of the lumbosacral spine. Contrast medium was injected and CT was used to assess the success of the injection. The anatomic landmarks to carry out the procedure were the seventh lumbar vertebra, the iliac wings, and the first sacral vertebra. The target for directing the needle was the trapezoid-shaped echogenic zone between the contiguous articular facets of the lumbosacral vertebral canal visualized in a parasagittal plane. The spinal needle or epidural catheter was inserted in a 45° craniodorsal–caudoventral direction through the subcutaneous tissue and the interarcuate ligament until reaching the epidural space. CT examination confirmed the presence of contrast medium in the epidural space in 25/25 dogs, although a variable contamination of the subarachnoid space was also noted. Findings indicated that this ultrasound-guided epidural injection technique is feasible for normal weight and overweight dogs, with and without radiographic abnormalities of the spine.
Sacrococcygeal epidural anaesthesia allows selective desensitisation of the sacral plexus. Ultrasound is used for guidance in human anaesthesia to facilitate sacrococcygeal epidural injections. The aims of this study were to describe the sonographic appearance of the sacrococcygeal region in dogs and a technique for performing epidural injection at this location under ultrasound guidance. In the preliminary part of the study four cadavers were used to describe the sonoanatomy of the sacrococcygeal space and to develop the ultrasound-guided puncture technique. In the second phase of the study this technique was repeated in four dogs under general anaesthesia. In all dogs the sacrococcygeal space appeared as a circular hypoechoic region, located caudal to the sacral caudal articular processes, delimited by bony hyperechoic structures such as body and arch of the first caudal vertebra. Ultrasound guidance allowed the operator to visualise and position the spinal needle into the sacrococcygeal epidural space. No complications were reported during this procedure. Preliminary results indicate that ultrasound-guided sacrococcygeal epidural anaesthesia may be considered as an alternative to a blind approach technique.
The use of ultrasound to guide peripheral nerve blocks is now a well-established technique in regional anaesthesia. However, despite reports of ultrasound guided epidural access via the paramedian approach, there are limited data on the use of ultrasound for central neuraxial blocks, which may be due to a poor understanding of spinal sonoanatomy. The aim of this study was to define the sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach.
The sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach was defined using a "water-based spine phantom", young volunteers and anatomical slices rendered from the Visible Human Project data set.
The water-based spine phantom was a simple model to study the sonoanatomy of the osseous elements of the lumbar spine. Each osseous element of the lumbar spine, in the spine phantom, produced a "signature pattern" on the paramedian sagittal scans, which was comparable to its sonographic appearance in vivo. In the volunteers, despite the narrow acoustic window, the ultrasound visibility of the neuraxial structures at the L3/L4 and L4/L5 lumbar intervertebral spaces was good, and we were able to delineate the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach.
Using a simple water-based spine phantom, volunteer scans and anatomical slices from the Visible Human Project (cadaver) we have described the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach in the lumbar region.
Poor surface anatomic landmarks are highly predictive of technical difficulty in neuraxial blockade. The authors examined the use of ultrasound imaging to reduce this difficulty.
The authors recruited 120 orthopedic patients with one of the following: body mass index more than 35 kg/m² and poorly palpable spinous processes; moderate to severe lumbar scoliosis; or previous lumbar spine surgery. Patients were randomized to receive spinal anesthetic by the conventional surface landmark-guided technique (group LM) or by an ultrasound-guided technique (group US). Patients in group US had a preprocedural ultrasound scan to locate and mark a suitable needle insertion point. The primary outcome was the rate of successful dural puncture on the first needle insertion attempt. Normally distributed data were summarized as mean ± SD and nonnormally distributed data were summarized as median [interquartile range].
The first-attempt success rate was twice as high in group US than in group LM (65% vs. 32%; P < 0.001). There was a twofold difference between groups in the number of needle insertion attempts (group US, 1 [1-2] vs. group LM, 2 [1-4]; P < 0.001) and number of needle passes (group US, 6 [1-10] vs. group LM, 13 [5-21]; P = 0.003). More time was required to establish landmarks in group US (6.7 ± 3.1; group LM, 0.6 ± 0.5 min; P < 0.001), but this was partially offset by a shorter spinal anesthesia performance time (group US, 5.0 ± 4.9 vs. group LM, 7.3 ± 7.6 min; P = 0.038). Similar results were seen in subgroup analyses of patients with body mass index more than 35 kg/m and patients with poorly palpable landmarks.
Preprocedural ultrasound imaging facilitates the performance of spinal anesthesia in the nonobstetric patient population with difficult anatomic landmarks.
The role of ultrasound in central neuraxial blockade has been underappreciated, partly because of the relative efficacy of the landmark-guided technique and partly because of the perceived difficulty in imaging through the narrow acoustic windows produced by the bony framework of the spine. However, this also is the basis for the utility of ultrasound: an interlaminar window that permits passage of sound waves into the vertebral canal also will permit passage of a needle. In addition, ultrasound aids in identification of intervertebral levels, estimation of the depth to epidural and intrathecal spaces, and location of important landmarks, including the midline and interlaminar spaces. This can facilitate neuraxial blockade, particularly in patients with difficult surface anatomic landmarks. In this review article, the authors summarize the current literature, describe the key ultrasonographic views, and propose a systematic approach to ultrasound imaging for the performance of spinal and epidural anesthesia in the adult patient.
Subarachnoid lumbar puncture is used commonly in the dog for cerebrospinal fluid collection and/or myelography. Here in we describe the percutaneous ultrasound anatomy of the lumbar region in the dog and a technique for ultrasound-guided lumbar puncture. Ultrasound images obtained ex vivo and in vivo were compared with anatomic sections and used to identify the landmarks for ultrasound-guided lumbar puncture. The ultrasound-guided procedure was established in cadavers and then applied in vivo in eight dogs. The anatomic landmarks for the ultrasound-guided puncture, which should be identified on the parasagittal oblique ultrasound image are the articular processes of the fifth and sixth lumbar vertebrae and the interarcuate space. The spinal needle is directed under ultrasound-guidance toward the triangular space located between the contiguous articular processes of the fifth and sixth lumbar vertebrae and then advanced to enter the vertebral canal. Using these precise ultrasound anatomic landmarks, an ultrasound-guided technique for lumbar puncture is applicable in the dog.
Seventy-five patients requesting extradural analgesia for the relief of pain in labour underwent an ultrasound scan to measure
the depth to the extradural space. There was a high degree of correlation between these measurements and the subsequent depth
of insertion of the Tuohy needle. The advantages of the technique in clinical practice and as an aid to teaching, are discussed
Lumbar epidural anesthesia was performed in 26 patients by an anesthesiology resident at either the L2-L3 or L3-L4 interspace using the loss-of-resistance technique. Measurements obtained ultrasonically the night before were not available to this resident. In the 22 successful epidural anesthetics, a good correlation between predicted distance (ultrasound) and measured needle distance occurred (r=0.99, p<0.0001). Average distance to the epidural space was 4.6 cm by both a priori ultrasound and a posteriori needle measurements. Among the 26 lumbar epidural anesthetics, four blocks were unsuccessful. Two unsuccessful blocks were characterized by a centimeter difference between the ultrasound measured distance and the needle measured distance. The other two unsuccessful blocks were due to accidental dislodgement of the catheter from the epidural space with removal of the needle.
Epidural anaesthesia (EA) is the most important analgesia technique in obstetrics for delivery. In pregnancy, hormonal adjustments lead to an alteration of tissue consistency, which often causes an early, untimely loss of resistance. Apart from mere inspection and palpation, no useful diagnostic method prior to EA performance has been established yet. In this prospective study, we examined 100 pregnant women, who had been admitted for childbirth and were undergoing epidural block (level L3-L4) for delivery. Sonotopography of the lumbar epidural structures was performed directly before epidural puncture and childbirth. We evaluated the visibility of all anatomical structures and compared all distances measured by ultrasonography and during puncture. The correlation between distances measured by ultrasound and by puncture needle was high (r2 = 0.79). No obvious dependency was found between ultrasonic and puncture angle (r2 = 0.19). The temporal distance from ultrasonic examination and puncture causes unavoidable differences: each deviation between ultrasound and puncture conditions causes a modification of the puncture depth. The patient acceptance of the procedure was very good. Ultrasonography offers the possibility to determine site and direction of epidural puncture and distance of the epidural space to the skin even before the puncture attempt. The ultrasound controlled EA for delivery can easily be inserted into the clinical routine. Ultrasonography can fill an important diagnostic gap in regional anaesthesia.
To establish a useful ultrasonic approach to the epidural space so as to optimize pre-puncture diagnostics.
Prospective study.
University clinic.
60 participants (19 to 34 years of age), 40 healthy volunteers (20 male, 20 female) and 20 parturients.
Ultrasound scanning of the lumbar spine was performed at the L(3)-L(4) vertebral interspace. Three ultrasound planes were employed: the transverse, median, and paramedian longitudinal approaches.
We compared the width of the ultrasound-permeable area in the median and paramedian planes and assessed the visibility of the epidural space and its surrounding structures.
In the paramedian plane, the permeable window was larger (p < 0.001) than in the median approach. The visibility of the ligamentum flavum (p < 0.0001), dura mater (p < 0.0001), and cauda equina (p < 0.0001) was significantly higher. Pulsation of epidural vessels could be observed more frequently (p < 0.0001) in the paramedian plane.
The longitudinal paramedian plane provided information about the epidural space depth in excellent imaging quality. The additional information might be beneficial in epidural anesthesia and in other clinical specialties (e.g., neurosurgery, trauma care).
The efficacy of epidural anaesthesia depends on the accurate identification of the epidural space (ES). Abnormal anatomical conditions may make the procedure difficult or impossible. The aim of this study was to investigate whether pre-puncture ultrasound examination of the spinal anatomy might be beneficial in expected cases of difficult epidural anaesthesia.
We used digital ultrasound equipment with a 5-MHz transducer to assess the anatomy of the ES and the posterior parts of the spinal column. We examined 72 parturients with abnormal anatomical conditions who were scheduled for epidural anaesthesia. The women were randomised into two equal groups. In all patients, the standard loss of resistance technique was used. In the ultrasound group, an ultrasound examination of the appropriate spinal region was conducted prior to epidural puncture. ES depth seen on the ultrasound images was compared to the ES depth measured by the needle. We compared the number of puncture attempts with the standard method (control group) to the number of attempts under ultrasound guidance.
Ultrasonography significantly improved operating conditions for epidural anaesthesia. The maximum VAS scores and patient acceptance were significantly better.
With ultrasound measurement of the ES depth, the quality of epidural anaesthesia was enhanced.
In recent studies, ultrasonic diagnostic imaging has proved useful in the screening of the trajectory of the epidural needle. With regard to possible side-effects of spinal and epidural anaesthesia caused by vessel injury, we aimed to evaluate the usability of Colour Doppler imaging for the depiction of interspinous vessels in prepuncture examination.
Ultrasonic examination of the L3/4 interspace area was performed in 20 volunteers. Using a 4-MHz and a 7-MHz probe with B-mode and Colour Doppler imaging, respectively, we compared four settings for the quality of vessel depiction in the puncture area. Overall resolution was evaluated according to the distinction of landmarks. Vascular structures were identified by pulsation (B-mode) or blood flow (Doppler).
Colour Doppler imaging of the L3/4 interspace was unachievable using the 7-MHz transducer. Vessel detection was possible in 50% of the B-mode images and in all of the 4-MHz Doppler images. Vessels were perceptible from a diameter of 0.5 mm. Veins were the predominantly visible structures. Overall vessel visibility was best using 4-MHz Colour Doppler.
Prepuncture Doppler imaging can provide the epiduralist with information regarding the position of vessels in the needle trajectory. This might help to reduce complications in regional anaesthesia.
In thoracic epidural anesthesia, the "loss of resistance" technique is the standard technique for the identification of the epidural space (EDS), the feedback to the operator is often solely tactile. Our aim was to establish ultrasonography for the prepuncture demonstration of the anatomic structures surrounding the thoracic EDS and to evaluate its precision and imaging quality.
We examined 20 volunteers. In each participant, the extradural space and the neighboring anatomic landmarks in the intervertebral space Th 5-6 were identified using 2 imaging techniques: magnetic resonance imaging (MRI) and ultrasonography. We compared corresponding images regarding distance measurements and the visibility of anatomic landmarks.
The capacity of ultrasound imaging (US) to depict the thoracic EDS was limited. Due to the better overview, MR images were easier to interpret. However, US proved to be of better value than MRI in the depiction of the dura mater. All important landmarks for the puncture of the thoracic EDS could be identified with both techniques. The overall correlation was satisfactory. US depicted the different structures of the thoracic EDS with an acceptable precision (confidence interval, 4.6 to 8.7 mm).
US showed good correlation with MRI, which is a standard imaging technique for the depiction of the spine. We anticipate that prepuncture ultrasonography may facilitate thoracic epidural anesthesia by needle placement.
To assess the clinical use of ultrasonographic localization of the epidural space, and to evaluate the clinical efficacy of ultrasound diagnostics in obstetric anesthesia.
Randomized prospective study.
University Clinic of Obstetrics and Gynecology.
300 parturients, 85 of whom had conventional delivery and 65 who underwent cesarean section.
Patients underwent ultrasonography for the identification of the intervertebral structures. Puncture depth and angle were measured to improve the placement of the Tuohy needle.
In the ultrasound group, additional puncture data, optimized puncture point, expected puncture depth, and angle were used to optimize the puncture technique. To control for side effects, we compiled data on the number of puncture attempts and the number of necessary puncture levels, visual analog scale (VAS) scores, the rate of side effects, and the patient acceptance of the technique.
The two groups were similar regarding demographic data. Using ultrasound for structure detection, the rate of puncture attempts were significantly (p < 0.013) reduced from 2.18 +/- 1.07 to 1.35 +/- 0.61. The mean rate of necessary puncture levels was 1.30 +/- 0.55 and with ultrasound detection 1.136 +/- 0.36 (p < 0.029). Complete analgesia was achieved in 147 patients with ultrasound detection versus 138 patients in the Control group (p < 0,03). The maximum VAS pain score in the control group was 1.3 +/- 2.1 versus 0.8 +/- 1.5 in the Ultrasound group (p < 0.006). The rate of side effects were reduced significantly: 99 patients in the Control group had no side effects compared with 120 patients from the Ultrasound group who were free of side effects. Patient acceptance of the technique in the Ultrasound group was significantly higher than in the Control group.
The clinical use of ultrasound for epidural catheter placement may improve regional anesthesia. The use of ultrasound resulted in superior quality in all measured endpoints.
The quality of combined spinal-epidural anaesthesia mainly depends on accurate identification of the epidural space. The real-time ultrasound control of the procedure for puncture was therefore evaluated.
Thirty parturients scheduled for Caesarean section were randomized to three equal groups. Ten control patients received conventional combined spinal-epidural anaesthesia. Ten of the remaining patients received ultrasonic scans by an offline scan technique, and 10 received online imaging of the lumbar region during epidural puncture. The epidural space was identified and needle advancement was surveyed through the interspinal and flaval ligaments. The number of attempts to advance the needle to achieve a successful puncture was measured and compared, as well as the number of vertebral interspaces punctured before successful entry into the epidural space.
There was no difference between patient characteristics in the three groups. The visualization of the epidural structures and of the needle manipulations was very effective. In the ultrasound group, the reduction in the number of attempts at puncture was significant (P < 0.036). The number of interspaces necessary for puncture was reduced (P < 0.036) in the ultrasound online group compared with controls. The number of spinal needle manipulations was significantly reduced (P < 0.036).
Real-time ultrasonic scanning of the lumbar spine is an easy procedure. It provides an accurate reading of the location of the needle tip and facilitates the performance of combined spinal-epidural anaesthesia.
The use of ultrasound as a diagnostic tool for the visualisation of the epidural space has effects on the quality and the performance of epidural anesthesia. This work presents an overview of the recent experiences with ultrasound for epidural anesthesia and on the possibilities for ultrasound imaging techniques. The results of visualisation of the epidural space and its limiting structures obtained by various working groups are presented. We review all presently available data on the prediction of the puncture depth. The various working groups found correlations between predicted and effective puncture depth between 0.79 and 0.98 and the precision of the measurement was 57-7.7 mm. Regarding the prediction of the puncture angle there was a poor correlation ranging between 0.07 and 0.31. The precision between the measured and the punctured angles was found to be 10-13.4 degrees. In all available prospective randomised studies on the puncture effects in the lumbar epidural space, the influence of ultrasound showed a significant reduction ( p<0.03) of the puncture attempts,and we found a significant ( p<0.05) reduction in the number of puncture levels. The ultrasound-guided puncture allowed an ideal needle trajectory and a more precise application of the catheter. A significant improvement of analgesia quality ( p<0.035) and patient satisfaction ( p<0.006) could be achieved. The metaanalysis of the different studies regarding puncture quality by ultrasound-guided peridural anaesthesia showed a clear advantage for the use of imaging techniques.
Paramedian access to the epidural space: the optimum window for ultrasound imaging
- T Grau
- R Leipold
- J Horter
Grau T, Leipold R, Horter J et al. (2001c) Paramedian
access to the epidural space: the optimum window for
ultrasound imaging. J Clin Anesth 13, 213-217.
Ultrasound imaging facilitates localization of the epidural space during combined spinal and epidural anesthesia
- Grau
Paramedian access to the epidural space: the optimum window for ultrasound imaging
- Grau
Colour Doppler imaging of the interspinous and epidural space
- Grau
Ultrasound imaging of the thoracic epidural space
- Grau