Psychophysical responses to needling depth using ultrasound imaging.

Thoracic paravertebral block has usually been performed using a loss of resistance technique [1, 2] with the transverse process is an important landmark. However, since the transverse process is neither visible nor palpable, its location is unknown until the block needle encounters the bone. If it is not encountered, the needle tip might advance further causing pleural puncture. Pusch et al. showed that ultrasound scanning of the transverse process and parietal pleura gave an accurate reading of the depth to the paravertebral space [3], but only made the measurements before, not during paravertebral block at T4. Breast surgery is often performed with axillary dissection making additional thoracic paravertebral blocks necessary at several vertebrae. We sought to determine whether visualisation of anatomical landmarks, needle advancement and the spread of local anaesthetic in the paravertebral space as well as knowledge of the distance from the skin to those landmarks using ultrasound imaging could help perform the block at both T1 and T4. With Institutional Review Board approval and written informed consent, 25 healthy patients undergoing unilateral breast surgery received thoracic paravertebral block combined with general anaesthesia. They were placed in the lateral decubitus position with the side to be blocked uppermost. A 3–11 MHz linear array probe (Philips SONOS 5500; Philips Medical Systems, Andover, MA, USA) was applied longitudinally to the paravertebral area. An 18G Tuohy needle was inserted perpendicularly at T4 to hit the transverse process via an out-of-plane approach. This was then directed over the top of the bony structure. The deviation of the needle from the perpendicular line was kept at 15°. The paravertebral space was identified using loss of resistance to normal saline injection without ultrasound. After negative aspiration, 15 ml of 0.5% ropivacaine was administered incrementally under ultrasound guidance. Thoracic paravertebral block at T1 was performed using the same technique with 5 ml of solution. Sensory block was assessed by loss of cold sensation 10 min later. All patients received the block at T4 and 22 at T1. Both parietal pleura and transverse process were successfully visualised at T4 (Fig. 3a) in all patients, while only transverse process visualisation was possible at T1. The distances measured using ultrasound and needle depth are in Table 1. Distances measured using ultrasound correlated well with needle depth. Injection of local anaesthetic was visualised as turbulence at T4 in all patients. Downward movement of pleura was observed at T4 in four patients during injection (Fig. 3b). No accidental pleural puncture occurred. All patients had loss of cold sensation at least between T2 and T4. Ultrasound imaging not only helped determine needle insertion sites, but also provides information on the depth to the paravertebral space. Ultrasound imaging may make thoracic paravertebral block easier to perform and help avoid inadvertent pleural puncture. (a) Measurements of the distances from the skin to the transverse process and pleura on ultrasound longitudinal image at T4. TP = transverse process, PP = parietal pleura, LIG = intertransverse and superior costotransverse ligaments. , distance from the skin to TP; , distance from the skin to PP. (b) Visualisation of local anaesthetic and the downward shift of PP on ultrasound longitudinal image. (A) Before injection, (B) After injection. TP = transverse process, PP = parietal pleura, LA = local anaesthetic.

Pre-procedural ultrasound (US) imaging as a tool of determining the proper insertion site and assessing lumbar-epidural depth in obese Indian parturients. The current study’s goal was to assess the epidural depth space in obese Indian parturients by ultrasound imaging with conventional technique and also to assess whether if it decreases the failure rate and number of attempts. Twenty-five obese parturients with a BMI of more than 30 kg/m who were scheduled for elective lower segment caesarean sections under lumbar epidural anesthesia and were classified as American Society of Anaesthesiology grade I & II were included. Using a curvilinear US probe (frequency 2–5 MHz), ultrasound depth-UD (lumbar epidural) was recorded in the transverse axial plane at the L3–L4 and L4–L5 intervertebral regions. Afterwards, the needle depth (ND) was monitored using a sterile linear scale during the epidural administration process using the traditional loss of resistance (LOR) approach. Any modifications to the intervertebral spacing, needle reorientation, or the quantity of tries were recorded. The results showed that UD and ND were, respectively, 4.6140 ± 0.252 cm (range 4.20–5.30 cm) and 4.720 ± 0.271 cm (range 4.2–5.5 cm). Pearson's correlation coefficient (r) for UD and ND was 0.953 (95% confidence interval: 0.8948–0.9793, r = 0.908, P < 0.001), and the 95% limits of agreement were found to be 0.266 to 0.546 cm using Bland-Altman analysis. Of all the subjects, 92% needed only one try to put the epidural, whereas 8% needed two. The current study demonstrates a significant association of ultrasound (UD) and needle depth (ND) in obese pregnant females (BMI >30 kg/m). For lumbar epidurals, a preprocedural US scan in the transverse-axial plane provides a precise needle entry site with a high success rate.

Ultrasound Imaging of the Thoracic Spine in Paramedian Sagittal Oblique Plane

AIUM Practice Parameter for the Use of Ultrasound to Guide Vascular Access Procedures.

The risk of nerve injury for pediatric thoracic epidural block increases stress for anesthesiologists. The purpose of this study was to investigate the usefulness of longitudinal ultrasound imaging for thoracic epidural block (T5-T6 or T6-T7) in anesthetized children scheduled for the Nuss procedure. Neuraxial structure in the longitudinal paramedian section was observed using ultrasound imaging before epidural puncture (US group, n=10). In the control group, usual epidural block without ultrasound was performed. Attempts were made to observe epidural catheterization in ultrasound imaging in three cases. Patient age ranged from 5 to 7years. Time for epidural block in the US group [100 (77-116)s; median value (95% confidence interval)] was significantly shorter than that in the control group [165 (130-206)s; P=0.001]. The difficulty score was significantly lower in the US group than in the control group (P<0.001). Epidural catheterization was observed in all three cases in which the catheter manipulated the dura mater ventrally. There was a high correlation (r=0.98, P<0.001) between needle depth and ultrasound estimation of the skin-dura distance in the US group. We concluded that longitudinal paramedian ultrasound imaging could reduce performance time and the difficulty for anesthesiologists during epidural block.

Background: Acupoint CV23 is one of the most commonly used acupoints for the treatment of post-stroke dysphagia and tongue pain. However, care must be taken during the procedure to consider the position of glands and blood vessels in the subcutaneous space of the acupoint. Needling depths to the geniohyoid muscle reportedly range from 0.4 to 3.3 cm. Using ultrasound imaging, we aimed to observe the anatomical characteristics around acupoint CV23 to derive a safe needling depth.Methods: Ultrasound images of acupoint CV23 accessed from the Standard Ultrasound Image of Acupoint database were retrospectively analyzed for 30 participants aged in their 20s and 30s (15 male, 15 female), and the depth from the skin to the geniohyoid muscle was measured. Correlations between the needling depth and anthropometric factors (such as neck circumference) were analyzed.Results: The average needling depth to the geniohyoid muscle was 1.59 ± 0.49 cm (male; 1.43 ± 0.52 cm, female, 1.75 ± 0.42 cm, &lt;i&gt;p&lt;/i&gt; = 0.03). The geniohyoid muscle, anterior digastric muscles, and genioglossus muscle were observed in the subcutaneous area of acupoint CV23, and a risk of sublingual gland damage needs to be considered for oblique insertion of the acupuncture needle. No statistically significant correlations between the needling depth and anthropometric factors were observed.Conclusion: Acupoint CV23 has a relatively shallow needling depth, and considering the presence of blood vessels and glands in the sublingual space, visualizing the surrounding anatomical structures using ultrasound was helpful to ensure safe needling practice.

Surface marking technique to locate needle insertion point for ultrasound-guided neuraxial block

Image guidance is crucial for percutaneous tumor ablations, enabling accurate needle-like applicator placement into target tumors while avoiding tissues that are sensitive to injury and/or correcting needle deflection. Although ultrasound (US) is widely used for image guidance, magnetic resonance (MR) is preferable due to its superior soft tissue contrast. The objective of this study was to develop and evaluate an MR and US multi-modal image-guided navigation system with a needle manipulator to enable US-guided applicator placement during MR imaging (MRI)-guided percutaneous tumor ablation. The MRI-compatible needle manipulator with US probe was installed adjacent to a 3 Tesla MRI scanner patient table. Coordinate systems for the MR image, patient table, manipulator, and US probe were all registered using an optical tracking sensor. The patient was initially scanned in the MRI scanner bore for planning and then moved outside the bore for treatment. Needle insertion was guided by real-time US imaging fused with the reformatted static MR image to enhance soft tissue contrast. Feasibility, targeting accuracy, and MR compatibility of the system were evaluated using a bovine liver and agar phantoms. Targeting error for 50 needle insertions was 1.6±0.6mm (mean±standard deviation). The experiment confirmed that fused MR and US images provided real-time needle localization against static MR images with soft tissue contrast. The proposed MR and US multi-modal image-guided navigation system using a needle manipulator enabled accurate needle insertion by taking advantage of static MR and real-time US images simultaneously. Real-time visualization helped determine needle depth, tissue monitoring surrounding the needle path, target organ shifts, and needle deviation from the path.

ABSTRACTObjective: When inserting a dry needle laterally into the upper lumbar spine (L1-L3) there is an increased risk of piercing the kidney; therefore, the objective of this study was to determine a zone of safety for practitioners to needle in the upper lumbar spine.Methods: Ten cadavers were screened for inclusion. L1 spinous process was identified and confirmed with ultrasound imaging. A digital caliper was used to measure laterally at 1.5 cm, 2.0 cm, and 2.5 cm. Dry needles were inserted maximally at each point and a binary decision, yes or no, was made to determine if bony contact was made. Needle depth and abdominal width measurements were also recorded. Safety of the dry needling procedure was interpreted as such if bony contact was made by the needle. If bony contact was made, then it was assumed that the needle cannot advance further into pleura or kidney.Results: Forty-four percent of needles did not make bony contact at 2.5 cm lateral of the L1 spinous process, whereas 22% did not make bony contact at 1.5 cm and 2.0 cm. There was a weak to moderate negative correlation between abdominal width measurements and needle depth at 1.5 cm (−0.48) and 2.0 cm (−0.45), and at 2.5 cm (−0.39).Conclusion: A safety zone of needling less than 2.5 cm is likely safe, but needs to be confirmed with future study. Dry needling 2.5 cm lateral appears more risky due to the higher frequency of not contacting a bony backdrop.

Proximal vs Distal Approach of Ultrasound-guided Suprascapular Nerve Block for Patients With Adhesive Capsulitis of the Shoulder: Prospective Randomized Controlled Trial

Prepuncture lumbar ultrasound scanning is a reliable tool to facilitate labor epidural needle placement in nonobese parturients. In this study, we assessed prepuncture lumbar ultrasound scanning as a tool for estimating the depth to the epidural space and determining the optimal insertion point in obese parturients. We studied 46 obese parturients, with prepregnancy body mass index (BMI) >30 kg/m(2), requesting labor epidural analgesia. Ultrasound imaging was done by one of the investigators to identify the midline, the intervertebral space, and the distance from the skin to the epidural space (ultrasound depth, UD) at the level of L3-4. Subsequently, an anesthesiologist blinded to the UD located the epidural space through the predetermined insertion point and marked the actual distance from the skin to the epidural space (needle depth, ND) on the needle with a sterile marker. The agreement between the UD and the ND was calculated using the Pearson correlation coefficient and a paired t-test. Bland-Altman analysis was used to determine the 95% limits of agreement between the UD and the ND. The prepregnancy BMI ranged from 30 to 79 kg/m(2), and the BMI at delivery was 33-86 kg/m(2). The Pearson correlation coefficient between the UD and the ND was 0.85 (95% confidence interval: 0.75-0.91), and the concordance correlation coefficient was 0.79 (95% confidence interval: 0.71-0.88). The mean (+/-SD) ND and UD were 6.6 +/- 1.0 cm and 6.3 +/- 0.8 cm, respectively (difference = 0.3 cm, P = 0.002). The 95% limits of agreement were 1.3 cm to -0.7 cm. Epidural needle placement using the predetermined insertion point was done without reinsertion at a different puncture site in 76.1% of parturients and without redirection in 67.4%. We found a strong correlation between the ultrasound-estimated distance to the epidural space and the actual measured needle distance in obese parturients. We suggest that prepuncture lumbar ultrasound may be a useful guide to facilitate the placement of epidural needles in obese parturients.

Although a maxillary nerve (MN) block reportedly provides satisfactory analgesia for midface surgery and chronic maxillofacial pain syndromes, a safe and reliable MN block technique has not been reported. The goal of this anatomical study was to quantify the various angles and depth of the block needle, as well as to evaluate the impact of volume on the extent of injectate spread that might influence anesthetic coverage and block-related complications. Following an ultrasound-guided suprazygomatic MN block with dye injection, a dissection was performed in the pterygopalatine fossa (PPF) of four lightly embalmed cadaveric specimens. Half of the specimens were injected with 5 mL of dye, and the other half with 1 mL of dye. The needle depth was measured from the ultrasound images and using rubber markers. Following injection, dissection was performed to map the area of dye spread. The median [interquartile range (IQR)] distance from the skin to the PPF was 37 [36-43] mm and 47 [40-50] mm by ultrasound and rubber marker methods, respectively. The median [IQR] needle orientation was 14 [11-32] degrees inferiorly and 15 [10-17] degrees posteriorly. The PPF was consistently dyed in the 5 mL group, but sporadically dyed in the 1 mL group. In the 5 mL group, spread outside of the PPF was seen. We showed that 5 mL of injectate far exceeds the capacity of the PPF, leading to drug spread outside of the PPF. Moreover, we found that 1 mL of injectate largely covered the nerve, suggesting a more efficacious and safer block procedure. This finding will need confirmation in future clinical studies.

Obstetric Anesthesia Digest: June 2010 - Volume 30 - Issue 2 - p 120-121 doi: 10.1097/01.aoa.0000370541.97413.dc

Obturator nerve block is one of the most technically challenging regional anesthesia techniques. Recently, the characteristics of the nerve have been described using ultrasound. However, clinical application of proximal ultrasound-guided obturator nerve block on patients has not been reported. In this study, we used ultrasound to describe the anatomical localization of the obturator nerve and its two branches in cadavers, volunteers, and also patients. A hyperechoic triangular shape formed by the superior pubic ramus, posterior margin of the pectineus muscle and anterior aspect of the external obturator muscle containing the obturator vessels and nerve was defined by ultrasound imaging in cadavers. In eight volunteers, bilateral obturator nerve images were obtained and the distances to specific landmarks (femoral artery, femoral vein, and pubic tubercle) were recorded. Ultrasound-guided obturator nerve block was further performed in 15 patients by using the previously defined approach. The final distance of the needle tip to the femoral artery, distances between the needle insertion point to the pubic tubercle and the depth of needle insertion were recorded. The rates of common obturator nerve, anterior and branching obturator nerve pattern visibility with ultrasound were determined in 12/16, 13/16, and 7/16 sites in volunteers, respectively. Mean (SD) values of critical landmarks obtained from volunteers were obturator nerve-femoral vein 12.9 +/- 2.9 mm and obturator nerve-pubic tubercle 19.9 +/- 2.6 mm. Mean measurements obtained from patients were: femoral artery- needle tip 18.5 +/- 2.4 mm, needle depth 48.3 +/- 10.4 mm, pubic tubercle- needle insertion point (horizontal) 18.8 +/- 2.0 mm, and pubic tubercle- needle insertion point (vertical) 21.1 +/- 2.9 mm. Visual analog scale scores obtained from patients at 1 and 24 h were lower compared to baseline values (P < 0.001). Ninety-three percent (14 of 15) of the patients reported satisfaction from the block. Landmarks defined in this clinical trial can be used in patients for obturator nerve block with ultrasound guidance.

The use of ultrasound to assist epidural injection in obese dogs