In-Vivo Obstetric Pressure Measurements for Patient-Specific Epidural Simulator

2014 ◽  
Author(s):  
Neil Vaughan ◽  
Venketesh N. Dubey ◽  
Michael Y. K. Wee ◽  
Richard Isaacs
Keyword(s):  
Needle Insertion ◽  
Epidural Needle ◽  
Patient Specific ◽  
Pressure Measurements ◽  
Epidural Pressure ◽  
Loss Of Resistance ◽  
New Finding ◽  
The Mean ◽  
Thickness Measurements

The aim of this study was to measure changing pressures during Tuohy epidural needle insertions for obstetric parturients of various BMI. This has identified correlations between BMI and epidural pressure. Also we investigated links between BMI and the thicknesses and depths of ligaments and epidural space as measured from MRI and ultrasound scans. To date there have been no studies relating epidural pressure and ligament thickness changes with varying Body Mass Indices (BMI). Further goals following measurement of pressure differences between various BMI patients, were to allow a patient-specific epidural simulator to be developed, which has not been achieved before. The trial has also assessed the suitability of our in-house developed wireless pressure measurement device for use in-vivo. Previously we conducted needle insertion trial with porcine for validation of the measurement system. Results showed that for each group average pressures during insertion decrease as BMI increases. Pressure measurements obtained from the patients were matched to tissue thickness measurements from MRI and ultrasound scans. The mean Loss of Resistance (LOR) pressure in each group reduces as BMI increases. Variation in the shape of the pressure graphs was noticed between two epiduralists performing the procedure, suggesting each anaesthetist may have a signature graph shape. This is a new finding which offers potential use in epidural training and assessment. It can be seen that insertions performed by the first epiduralist have a higher pressure range than insertions performed by second epiduralist.

scholarly journals In Vivo Quantification of Regional Circumferential Green Strain in the Thoracic and Abdominal Aorta by Two-Dimensional Spiral Cine DENSE MRI

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
John S. Wilson ◽  
Xiaodong Zhong ◽  
Jackson Hair ◽  
W. Robert Taylor ◽  
John N. Oshinski
Keyword(s):  
Abdominal Aorta ◽  
Aortic Wall ◽  
Patient Specific ◽  
Peak Strain ◽  
Ssfp Cine ◽  
Green Strain ◽  
The Mean ◽  
Thoracic And Abdominal ◽  
Cine Dense

Regional tissue mechanics play a fundamental role in the patient-specific function and remodeling of the cardiovascular system. Nevertheless, regional in vivo assessments of aortic kinematics remain lacking due to the challenge of imaging the thin aortic wall. Herein, we present a novel application of displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) to quantify the regional displacement and circumferential Green strain of the thoracic and abdominal aorta. Two-dimensional (2D) spiral cine DENSE and steady-state free procession (SSFP) cine images were acquired at 3T at either the infrarenal abdominal aorta (IAA), descending thoracic aorta (DTA), or distal aortic arch (DAA) in a pilot study of six healthy volunteers (22–59 y.o., 4 females). DENSE data were processed with multiple custom noise reduction techniques including time-smoothing, displacement vector smoothing, sectorized spatial smoothing, and reference point averaging to calculate circumferential Green strain across 16 equispaced sectors around the aorta. Each volunteer was scanned twice to evaluate interstudy repeatability. Circumferential Green strain was heterogeneously distributed in all volunteers and locations. The mean spatial heterogeneity index (standard deviation of all sector values divided by the mean strain) was 0.37 in the IAA, 0.28 in the DTA, and 0.59 in the DAA. Mean (homogenized) peak strain by DENSE for each cross section was consistent with the homogenized linearized strain estimated from SSFP cine. The mean difference in peak strain across all sectors following repeat imaging was −0.1±2.3%, with a mean absolute difference of 1.7%. Aortic cine DENSE MRI is a viable noninvasive technique for quantifying heterogeneous regional aortic wall strain and has significant potential to improve patient-specific clinical assessments of numerous aortopathies, as well as to provide the lacking spatiotemporal data required to refine patient-specific computational models of aortic growth and remodeling.

Cervical and High Thoracic Ligamentum Flavum Frequently Fails to Fuse in the Midline

2003 ◽  
Vol 99 (6) ◽  
pp. 1387-1390 ◽  
Author(s):  
Philipp Lirk ◽  
Christian Kolbitsch ◽  
Guenther Putz ◽  
Joshua Colvin ◽  
Hans Peter Colvin ◽  
...  
Keyword(s):  
Ligamentum Flavum ◽  
Epidural Needle ◽  
Complete Fusion ◽  
Thoracic Epidural ◽  
Loss Of Resistance ◽  
Ligamenta Flava ◽  
Mean Width ◽  
Human Cadavers ◽  
The Mean ◽  
High Thoracic Epidural

Background Cervical and high thoracic epidural anesthesia and analgesia have gained increasing importance in the treatment of painful conditions and as components of anesthetics for cardiac and breast surgery. In contrast to the hanging-drop technique, the loss-of-resistance technique is thought to rely on the penetration of the ligamentum flavum. However, the exact morphology of the ligamentum flavum at different vertebral levels remains controversial. Therefore, the aim of this study was to investigate the incidence and morphology of cervical and high thoracic ligamentum flavum mid-line gaps in embalmed cadavers. Methods Vertebral column specimens were obtained from 52 human cadavers. On each dissected level, ligamentum flavum mid-line gaps were recorded and evaluated with respect to shape and size. Results The following variations were encountered: complete fusion in the mid-line, mid-line fusion with a gap in the caudal part, mid-line gap, and mid-line gap with widened caudal end. The incidence of mid-line gaps at the following levels was: C3-C4: 66%, C4-C5: 58%, C5-C6: 74%, C6-C7: 64%, C7-T1: 51%, Th1-Th2: 21%, Th2-Th3: 11%, Th3-Th4: 4%, Th4-Th5: 2%, and Th5-Th6: 2%. The mean width of mid-line gaps was 1.0 +/- 0.3 mm. Conclusions In conclusion, the present study shows that gaps in the ligamenta flava are frequent at cervical and high thoracic levels but become rare at the T3/T4 level and below, such that one cannot always rely on the ligamentum flavum as a perceptible barrier to epidural needle placement at these levels.

scholarly journals Measurements of Corneal Thickness in Eyes with Pseudoexfoliation Syndrome: Comparative Study of Different Image Processing Protocols

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Katarzyna Krysik ◽  
Dariusz Dobrowolski ◽  
Katarzyna Polanowska ◽  
Anita Lyssek-Boron ◽  
Edward A. Wylegala
Keyword(s):  
Time Domain ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Imaging Systems ◽  
Pressure Measurements ◽  
Swept Source ◽  
Swept Source Oct ◽  
The Mean ◽  
Thickness Measurements ◽  
Cataract Patients

Purpose. Comparative analysis of central and peripheral corneal thickness in PEX patients using three different imaging systems: Pentacam-Scheimpflug device, time-domain optical coherence tomography (OCT) Visante, and swept-source OCT Casia. Materials and Methods. 128 eyes of 80 patients with diagnosed PEX were examined and compared with 112 normal, non-PEX eyes of 72 cataract patients. The study parameters included 5 measured zones: central and 4 peripheral (superior, inferior, nasal, and temporal). Results. The mean CCT in eyes with PEX syndrome measured with all three instruments was thicker than that in normal eyes. Corneal thickness measurements in the PEX group were statistically significantly different between Pentacam and OCT Casia: central corneal thickness (p=0.04), inferior corneal zone (p=0.01), and nasal and temporal corneal zones (p<0.01). Between Pentacam and OCT Visante inferior, nasal and temporal corneal zones were statistically significantly different (p<0.01). Between OCT Casia and OCT Visante, there were no statistically significant differences in measured parameters values. Conclusion. The central corneal thickness in eyes with PEX syndrome measured with three different independent methods is higher than that in the non-PEX group, and despite variable peripheral corneal thickness, this one parameter is still crucial in intraocular pressure measurements.

scholarly journals Accuracy evaluation of a 3D-printed individual template for needle guidance in head and neck brachytherapy

2016 ◽  
Vol 57 (6) ◽  
pp. 662-667 ◽  
Author(s):  
Ming-Wei Huang ◽  
Jian-Guo Zhang ◽  
Lei Zheng ◽  
Shu-Ming Liu ◽  
Guang-Yan Yu
Keyword(s):  
Head And Neck ◽  
Needle Insertion ◽  
Accuracy Evaluation ◽  
Angular Deviation ◽  
3D Printed ◽  
Radioactive Seeds ◽  
The Mean ◽  
125I Radioactive Seeds ◽  
Time Required

Abstract To transfer the preplan for the head and neck brachytherapy to the clinical implantation procedure, a preplan-based 3D-printed individual template for needle insertion guidance had previously been designed and used. The accuracy of needle insertion using this kind template was assessed in vivo. In the study, 25 patients with head and neck tumors were implanted with 125I radioactive seeds under the guidance of the 3D-printed individual template. Patients were divided into four groups based on the site of needle insertion: the parotid and masseter region group (nine patients); the maxillary and paranasal region group (eight patients); the submandibular and upper neck area group (five patients); and the retromandibular region group (six patients). The distance and angular deviations between the preplanned and placed needles were compared, and the complications and time required for needle insertion were assessed. The mean entrance point distance deviation for all 619 needles was 1.18 ± 0.81 mm, varying from 0.857 ± 0.545 to 1.930 ± 0.843 mm at different sites. The mean angular deviation was 2.08 ± 1.07 degrees, varying from 1.85 ± 0.93 to 2.73 ± 1.18 degrees at different sites. All needles were manually inserted to their preplanned positions in a single attempt, and the mean time to insert one needle was 7.5 s. No anatomical complications related to inaccurately placed implants were observed. Using the 3D-printed individual template for the implantation of 125I radioactive seeds in the head and neck region can accurately transfer a CT-based preplan to the brachytherapy needle insertion procedure. Moreover, the addition of individual template guidance can reduce the time required for implantation and minimize the damage to normal tissues.

scholarly journals Robotic CT-guided out-of-plane needle insertion: comparison of angle accuracy with manual insertion in phantom and measurement of distance accuracy in animals

2019 ◽  
Vol 30 (3) ◽  
pp. 1342-1349 ◽  
Author(s):  
Toshiyuki Komaki ◽  
Takao Hiraki ◽  
Tetsushi Kamegawa ◽  
Takayuki Matsuno ◽  
Jun Sakurai ◽  
...  
Keyword(s):  
Animal Experiment ◽  
Animal Experiments ◽  
Smartphone Application ◽  
Needle Insertion ◽  
Phantom Experiment ◽  
Ct Guided ◽  
Key Points ◽  
Out Of Plane ◽  
The Mean

Abstract Objectives To evaluate the accuracy of robotic CT-guided out-of-plane needle insertion in phantom and animal experiments. Methods A robotic system (Zerobot), developed at our institution, was used for needle insertion. In the phantom experiment, 12 robotic needle insertions into a phantom at various angles in the XY and YZ planes were performed, and the same insertions were manually performed freehand, as well as guided by a smartphone application (SmartPuncture). Angle errors were compared between the robotic and smartphone-guided manual insertions using Student’s t test. In the animal experiment, 6 robotic out-of-plane needle insertions toward targets of 1.0 mm in diameter placed in the kidneys and hip muscles of swine were performed, each with and without adjustment of needle orientation based on reconstructed CT images during insertion. Distance accuracy was calculated as the distance between the needle tip and the target center. Results In the phantom experiment, the mean angle errors of the robotic, freehand manual, and smartphone-guided manual insertions were 0.4°, 7.0°, and 3.7° in the XY plane and 0.6°, 6.3°, and 0.6° in the YZ plane, respectively. Robotic insertions in the XY plane were significantly (p < 0.001) more accurate than smartphone-guided insertions. In the animal experiment, the overall mean distance accuracy of robotic insertions with and without adjustment of needle orientation was 2.5 mm and 5.0 mm, respectively. Conclusion Robotic CT-guided out-of-plane needle insertions were more accurate than smartphone-guided manual insertions in the phantom and were also accurate in the in vivo procedure, particularly with adjustment during insertion. Key Points • Out-of-plane needle insertions performed using our robot were more accurate than smartphone-guided manual insertions in the phantom experiment and were also accurate in the in vivo procedure. • In the phantom experiment, the mean angle errors of the robotic and smartphone-guided manual out-of-plane needle insertions were 0.4° and 3.7° in the XY plane (p < 0.001) and 0.6° and 0.6° in the YZ plane (p = 0.65), respectively. • In the animal experiment, the overall mean distance accuracies of the robotic out-of-plane needle insertions with and without adjustments of needle orientation during insertion were 2.5 mm and 5.0 mm, respectively.

Instrumentation of the Loss-of-Resistance Technique for Epidural Needle Insertion

2009 ◽  
Vol 56 (3) ◽  
pp. 820-827 ◽  
Author(s):  
D. Tran ◽  
King-Wei Hor ◽  
A.A. Kamani ◽  
V.A. Lessoway ◽  
R.N. Rohling
Keyword(s):  
Needle Insertion ◽  
Epidural Needle ◽  
Loss Of Resistance

Application of the coplanar principle to dynamic epidural pressure measurements

1984 ◽  
Vol 61 (4) ◽  
pp. 733-736 ◽  
Author(s):  
John Beck ◽  
Alfonso Schettini ◽  
Rhonda Salton
Keyword(s):  
Brain Tissue ◽  
Viscoelastic Properties ◽  
Displacement Transducer ◽  
Pressure Measurements ◽  
Dynamic Measurements ◽  
Epidural Pressure ◽  
Content Type ◽  
Fine Print

✓ The application of the coplanar principle to dynamic epidural pressure measurements was investigated in vitro. The authors used a coplanar pressure-displacement transducer, commonly employed to measure the viscoelastic properties of brain tissue in vivo. The present studies were performed using canine dura and a specially constructed fluid-filled chamber. The accuracy of the technique was assessed by comparing the pressure in the chamber recorded by the coplanar transducer to the pressure measured by a transducer directly vented to the chamber. The results show that the coplanar principle remained valid for dynamic measurements with the transducer under a variety of conditions.

scholarly journals Epidural Needle Extension through the Ligamentum Flavum Using the Standard versus the CompuFlo®-Assisted Loss of Resistance to Saline Technique: A Simulation Study

2020 ◽  
Vol 2020 ◽  
pp. 1-4
Author(s):  
E. Capogna ◽  
A. Coccoluto ◽  
M. Velardo
Keyword(s):  
Epidural Space ◽  
Simulation Study ◽  
Ligamentum Flavum ◽  
Standard Technique ◽  
High Sensitivity ◽  
Tuohy Needle ◽  
Epidural Needle ◽  
Loss Of Resistance ◽  
The Mean ◽  
Extension Length

Background. The CompuFlo® epidural system has been recently introduced and validated as an objective and sensible tool to detect the epidural space. We aimed to verify whether the high sensitivity of the instrument may help the anesthesiologist to identify the epidural space very early, limiting the extension of the Tuohy needle into the epidural space. Methods. In this prospective, simulation study, we evaluated the Tuohy needle extension through a simulated ligamentum flavum during the epidural procedure performed by 52 expert anesthesiologists by using the CompuFlo® epidural instrument or their standard loss of resistance to saline technique (LORT). Results. The mean (SD) needle extension length was 3.90 (3.71) mm in the standard technique group and 0.68 (0.46) mm in the CompuFlo® group (P<000001). The extremely reduced variability of the data in the CompuFlo® group (F test 0.01) made the results obtained with this instrument highly predictable. Conclusions. Puncturing high-resistance material that simulated the ligamentum flavum, the use of CompuFlo® has determined the arrest of the needle more precociously when compared with the traditional LORT.

Haptic Interface on Measured Data for Epidural Simulation

2012 ◽  
Author(s):  
Neil Vaughan ◽  
Venketesh N. Dubey ◽  
Michael Y. K. Wee ◽  
Richard Isaacs
Keyword(s):  
Force Feedback ◽  
Development Program ◽  
Needle Insertion ◽  
Haptic Device ◽  
Epidural Needle ◽  
High Fidelity ◽  
3D Graphics ◽  
Tissue Layer ◽  
Loss Of Resistance ◽  
Force Data

This paper presents a haptic device with 3D computer graphics as part of a high fidelity medical epidural simulator development program. The haptic device is used as an input to move the needle in 3D, and also to generate force feedback to the user during insertion. A needle insertion trial was conducted on a porcine cadaver to obtain force data. The data generated from this trial was used to recreate the feeling of epidural insertion in the simulator. The interaction forces have been approximated to the resultant force obtained during the trial representing the force generated by the haptic device. The haptic device is interfaced with the 3D graphics for visualization. As the haptic stylus is moved, the needle moves on the screen and the depth of the needle tip indicates which tissue layer is being penetrated. Different forces are generated by the haptic device for each tissue layer as the epidural needle is inserted. As the needle enters the epidural space, the force drops to indicate loss of resistance.

scholarly journals Intraocular pressure measurements with the Tono-Pen XL® and Perkins® applanation tonometers in horses and cattle

2013 ◽  
Vol 43 (5) ◽  
pp. 865-870 ◽  
Author(s):  
Silvia Franco Andrade ◽  
Rodrigo de Jesus Palozzi ◽  
Rodrigo Duarte Rolim ◽  
José Ricardo Cecílio Junqueira ◽  
Heloisa Ferreira do Valle ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Strong Correlation ◽  
Normal Values ◽  
Eye Drops ◽  
Pressure Measurements ◽  
Postmortem Study ◽  
Significant Difference ◽  
The Mean ◽  
Conscious Animals

The objective of this study was to compare the accuracy between two applanation tonometers, Tono-Pen XL® and Perkins®, in horses and cattle. The eyes of 20 horses and 20 cattle conscious and healthy were evaluated for the in vivo study and both eyes of 5 horses and 5 cattle were used as controls for the postmortem study. In conscious animals, the tonometry was performed with auriculopalpebral nerve block and then topical anesthesia for both tonometers and 1% fluorescein eye drops only for the Perkins tonometer. Readings of intraocular pressure (IOP) in the postmortem study were taken using manometry and tonometry by Tono-Pen XL® and Perkins®. The correlation coefficient (r²) between manometry and applanation tonometers Tono-Pen XL® and Perkins®, in horses, were 0.845 and 0.989, respectively, and in cattle, were 0.772 and 0.988, respectively. The mean IOP values in conscious horses with Tono-Pen XL® and Perkins® were 20.1±3.9mmHg and 20.9±3.2mmHg, respectively, and in conscious cattle, these values were 17.2±2.4mmHg and 17.9±1.4mmHg, respectively. There was a strong correlation between the IOP values obtained by direct ocular manometry and the Tono-Pen XL® and Perkins® tonometers in horses and cattle. There was no statistically significant difference between the mean IOPs obtained with both tonometers in conscious animals; however, there was a difference between the minimum values, which were on average 2-3 mmHg lower with the Tono-Pen XL® tonometer than with the Perkins® tonometer, which justifies a table of normal values differentiated for each tonometer.

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