Disclaimer. Disclosure 3/1/2014. Dennis Spence Ph.D., CRNA

Transcription

1 Dennis Spence Ph.D., CRNA Disclaimer The views expressed in this article are those of the author and do not reflect official policy or position of the Department of the Navy, the Department of Defense, the Uniformed Services University of the Health Sciences, or the United States Government. Disclosure Nothing else to disclose 1

2 3/1/2014 Objectives Review ultrasound basics Describe the use of pre-procedural ultrasound (U/S) assessment of sonoanatomy of the spine Discuss research findings on the use of preprocedural ultrasonography in parturients Provide some practical tips for incorporating U/S into practice Clinical Vignette A fellow CRNA calls for assistance G1P0 morbidly obese parturient requested a epidural at 4 cm dilation (63 & 365 lbs.) PMH: CHTN, OSA, morbid obesity OB: severe preeclampsia, platelets = 120K Airway: MP 4, 3 FB, limited ROM FHT: occasional late decelerations Exam: unable to palpate spinous processes Procedure: multiple attempts unsuccessful U/S performed Success on 1 st attempt Clinical Vignette 30 y/o w presents for repeat LTCS for twins PMH: -, Prenatal: uncomplicated Exam: exaggerated lumbar lordosis (61 & 80 kg) Airway: MP2, 3FB, FROM History of difficult epidural Labs: WNL SRNA- multiple attempts by SRNA & CRNA unsuccessful Nurse gets the ultrasound machine U/S scanning identifies ideal insertion L3-4 and depth to ligamentum flavum (LF) = 6 cm Original insertion points off midline by ~ 2 cm Spinal placed through ideal insertion point on first attempt without redirection 2

3 3/1/2014 Clinical Vignette An SRNA first day on OB (never placed labor epidural; CLE) A G1P0 parturient requests a epidural at 4 cm dilation (65 and 165 lbs) The student and staff palpate the back Staff performs U/S Marks ideal insertion point and estimates the depth to LF = 4 cm With coaching, SRNA achieves loss or resistance (LOR) at 4.3 cm Places epidural on the first attempt SRNA describes how she was able to focus on the feeling of LOR CRNA s anxiety level was less because he was confident in the insertion point and depth estimation What is Pre-Procedural U/S? Use of a curvilinear probe to identify lumbar spine sonoanatomy to facilitate placement of spinals and epidurals Not real-time U/S scan +/- palpate Scan two acoustic windows Longitudinal paramedian Transverse Estimate depth Mark the location Spence DL et al. AANA J ;80(3):1-8. Ultrasound Physics Seeing with Sound Basic Principles: Ultrasound is form of mechanical sound energy that travels through a conducting medium (e.g., tissue) and then gets reflected back to form an image 3

4 3/1/2014 U/S Theory & Terminology Ultrasound waves are created by piezoelectric crystals in transducer U/S waves penetrate tissue to different depths based on probe frequency High frequency probes (5-13 MHz) Great resolution, shallow depth Low frequency probes (2-5 MHz) Poor resolution, deep depth (up to 30 cm) Ultrasound Probes Linear Curved Array 4

5 3/1/2014 U/S Theory & Terminology Echogenicity U/S image depends on tissue density and ability of machine to reflect U/S waves back to transducer Hyperechoic Structures with greater propensity to reflect U/S wave Bones, nerves, vascular walls, connective tissue Images appear brighter on screen Hypoechoic Structures with less propensity to reflect U/S waves Blood vessels, lung, fluid filled structures, ect Images appear darker Acoustic impedance Reduction in U/S wave energy as it passes through structures Accounts for the depth limits of U/S Imaging Hypoechoic Hyperechoic Benefits of U/S in OB Anesthesia Identify best interspace Identify ideal insertion point Estimate depth to the epidural space Reduce attempts, trauma and complications Improve learning curve for trainees May assist with placement of epidural/spinal in the difficult back Scoliosis Back surgery Obesity 5

6 Probe Low frequency (2-5 MHz) curvilinear probe Acoustic Windows Longitudinal paramedian Sacrum Articular process Ligamentum flavum and posterior dura mater Anterior dura mater, post. long. lig., & vertebral body Transverse Spinous process Articular process Ligamentum flavum & posterior dura mater Anterior dura mater, post. long. lig., & vertebral body 6

7 Spence D et al. AANA J 2012; 80(3):1-8. 7

8 The = sign Flying Bat Spence D et al.aana J 2012; 80(3):1-8. Depth Estimation Freeze screen Place caliper at skin & inner side of LF Depth = 4.5 cm U/S underestimates LOR depth 8

9 Marking the Skin Spence D et al.aana J 2012; 80(3):1-8. Video Clip Ultrasound for Epidural Insertion Accessed March 1,

10 d e p t h i n c m 3/1/2014 Adapted from: Carvalho JC. Ultrasound-guided epidural anesthesia video tutorial. Accessed December 20, Review of Literature 16 studies on 1,373 patients 1 systematic review 5 randomized controlled trials 1 cohort study 1 case-control study 8 descriptive correlational studies Majority published by 2 groups Grau et al Carvalho et al C o m p a r i s o n o f U l t r a s o u n d & N e e d l e D e p t h U D N D M e a n D i f f e r e n c e : N o n o b e s e : ± c m O b e s e : 0. 3 ± 0. 5 c m 2 0 N o n o b e s e O b e s e r = t o L O R > 8 c m = 1 7 % May not need >10 cm epidural needle Balki M, Lee Y, Halpern S, Carvalho JC.. Anesth Analg. 2009;108(6): Arzola C, Davies S, Rofaeel A, Carvalho JC. Anesth Analg. 2007;104(5): Spence DL. Anesthesia Abstracts 2009;(3)7. 10

11 percentage of patients (%) 3/1/2014 Does U/S decrease number of attempts and improve success? Systematic review (Schnabel et al, 2010) U/S decreases # insertion attempts by 1 U/S decreases # puncture sites by st attempt success rate: 71% 1 st interspace success rate: 88% Limitation of studies All epidurals and U/S scans by experienced providers U/S 1st Attempt Success % 76% 74% 67% Nonobese Obese No reinsertions No redirections Balki M, Lee Y, Halpern S, Carvalho JC.. Anesth Analg. 2009;108(6): Arzola C, Davies S, Rofaeel A, Carvalho JC. Anesth Analg. 2007;104(5): U/S Image Quality Good image quality % Obesity reduces image quality Paramedian best image quality Pts with abnormal sonoanatomy 8.2 times more likely to experience wet tap (95% CI: 3-22, P <0.0001) Clinical implication: choose interspace with best image quality 11

12 success rate % 3/1/2014 Does U/S reduce epidural failure rate? Vallejo et al (2010) RCT N = 370 parturients 6.00% CLE placed by 1 st yr residents 5.00% supervised by staff 4.00% CLE failure rate = 3.00% pain >3/10 after 3 boluses 2.00% U/S < control 1.00% Grau et al (2003) 0.00% N = 300 difficult backs Incomplete analgesia rate higher in control group (8% vs. 2%, P<0.05) Epidural Failure Rate Control U/S Epidural Failure Rate P <0.05 Does U/S decrease complications? Systematic Review (Schnabel el al, 2010) PDPH 0.28 times lower (95% CI ) Incidence of back pain w/ placement similar Limitation Definition of PDPH mixed Publication & dominating center bias Epidurals placed by experienced providers Does U/S improve hasten trainee learning curve? Grau et al (2003) Randomized 10 residents to U/S or palpation alone Single staff performed U/S % 60% 94% 84% U/S Control P< Insertion point & angle Residents alone to place CLE 600 epidurals placed U/S improve proficiency in trainees Demonstrates value of U/S in teaching and learning st 10 CLE 1st 60 CLE 12

13 What about staff learning curve? Margarido et al (2010) 18 anesthesiologists attended 1 day hands-on CME course 20 trials (2 min each) to practice identifying ideal interspace, insertion point & ultrasound depth F/U 1-2 weeks later Only 27% competent at identifying ideal interspace w/ U/S None competent to identify insertion point or ultrasound depth to LF Conclusion: Hard to teach old dog new tricks To become competent need more experience Discussion Preprocedural U/S improves efficiency of CLE placement May improve success in difficult backs May help improve trainee success Takes less<5 minutes Can improve 1st attempt success rate w/ spinal Problem: does require a fair bit of experience to become competent Tip for Anesthetists Practice! Practice Practice! Practice scanning in controlled setting Look at a lot of ultrasound images Bring U/S machine in for easy epidurals or spinals Use preemptively in presumed difficult backs Use it to teach students 13

14 References 1. Dresner M, Brocklesby J, Bamber J. Audit of the influence of body mass index on the performance of epidural analgesia in labour and the subsequent mode of delivery. BJOG. 2006;113(10): Balki M, Lee Y, Halpern S, Carvalho JC. Ultrasound imaging of the lumbar spine in the transverse plane: the correlation between estimated and actual depth to the epidural space in obese parturients. Anesth Analg. 2009;108(6): Schnabel A, Schuster F, Ermert T, Eberhart LH, Metterlein T, Kranke P. Ultrasound Guidance for Neuraxial Analgesia and Anesthesia in Obstetrics: a Quantitative Systematic Review. Ultraschall Med Grau T, Bartusseck E, Conradi R, Martin E, Motsch J. Ultrasound imaging improves learning curves in obstetric epidural anesthesia: a preliminary study. Can J Anaesth. 2003;50(10): Vallejo MC, Phelps AL, Singh S, Orebaugh SL, Sah N. Ultrasound decreases the failed labor epidural rate in resident trainees. Int J Obstet Anesth. 2010;19(4): Falyar CR. Ultrasound in anesthesia: applying scientific principles to clinical practice. AANA J. 2010;78(4): Carvalho JC. Ultrasound-facilitated epidurals and spinals in obstetrics. Anesthesiol Clin. 2008;26(1): Chin KJ, Karmakar MK, Peng P. Ultrasonography of the adult thoracic and lumbar spine for central neuraxial blockade. Anesthesiology. 2011;114(6): References 9. Grau T, Leipold RW, Horter J, Conradi R, Martin EO, Motsch J. Paramedian access to the epidural space: the optimum window for ultrasound imaging. J Clin Anesth. 2001;13(3): Carvalho JC. Ultrasound-guided epidural anesthesia video tutorial. esthesia. Accessed December 20, Grau T, Leipold RW, Conradi R, Martin E. Ultrasound control for presumed difficult epidural puncture. Acta Anaesthesiol Scand. 2001;45(6): Grau T, Leipold RW, Conradi R, Martin E, Motsch J. Ultrasound imaging facilitates localization of the epidural space during combined spinal and epidural anesthesia. Reg Anesth Pain Med. 2001;26(1): Grau T, Leipold RW, Conradi R, Martin E, Motsch J. Efficacy of ultrasound imaging in obstetric epidural anesthesia. J Clin Anesth. 2002;14(3): Spence DL, Nations R, Rivera O, Bowdoin S, Hazen B, Orgill R, Maye J. Evidence-Based Anesthesia: The Use of Preprocedural Ultrasonography During Labor to Facilitate Placement of an Epidural Catheter. AANA J ;80(3):

15 References 15. Grau T, Leipold RW, Horter J, Conradi R, Martin E, Motsch J. The lumbar epidural space in pregnancy: visualization by ultrasonography. Br J Anaesth. 2001;86(6): Lee Y, Tanaka M, Carvalho JC. Sonoanatomy of the lumbar spine in patients with previous unintentional dural punctures during labor epidurals. Reg Anesth Pain Med. 2008;33(3): Arzola C, Davies S, Rofaeel A, Carvalho JC. Ultrasound using the transverse approach to the lumbar spine provides reliable landmarks for labor epidurals. Anesth Analg. 2007;104(5): Cork RC, Kryc JJ, Vaughan RW. Ultrasonic localization of the lumbar epidural space. Anesthesiology. 1980;52(6): Currie JM. Measurement of the depth to the extradural space using ultrasound. Br J Anaesth. 1984;56(4): Wallace DH, Currie JM, Gilstrap LC, Santos R. Indirect sonographic guidance for epidural anesthesia in obese pregnant patients. Reg Anesth. 1992;17(4): References 21. Borges BC, Wieczorek P, Balki M, Carvalho JC. Sonoanatomy of the lumbar spine of pregnant women at term. Reg Anesth Pain Med. 2009;34(6): Tran D, Kamani AA, Lessoway VA, Peterson C, Hor KW, Rohling RN. Preinsertion paramedian ultrasound guidance for epidural anesthesia. Anesth Analg. 2009;109(2): Margarido CB, Arzola C, Balki M, Carvalho JC. Anesthesiologists' learning curves for ultrasound assessment of the lumbar spine. Can J Anaesth. 2010;57(2): Margarido CB, Mikhael R, Arzola C, Balki M, Carvalho JC. The intercristal line determined by palpation is not a reliable anatomical landmark for neuraxial anesthesia. Can J Anaesth Balki M. Locating the epidural space in obstetric patients-ultrasound a useful tool: continuing professional development. Can J Anaesth. 2010;57(12): Chin KJ, Perlas A, Chan V, Brown-Shreves D, Koshkin A, Vaishnav V. Ultrasound imaging facilitates spinal anesthesia in adults with difficult surface anatomic landmarks. Anesthesiology. 2011;115(1): doi: /ALN.0b013e31821a8ad Weiss JL, Malone FD, Emig D, et al. Obesity, obstetric complications and cesarean delivery rate--a population-based screening study. Am J Obstet Gynecol. 2004;190(4): Grau T, Leipold RW, Fatehi S, Martin E, Motsch J. Real-time ultrasonic observation of combined spinal-epidural anaesthesia. Eur J Anaesthesiol. 2004;21(1):