Drozdzynska, M

Monticelli, P

Neilson, D M

Viscasillas, J

English

RVC Repository (Royal Veterinary College)

  RVC OPEN ACCESS REPOSITORY – COPYRIGHT NOTICE  This is the peer reviewed version of the following article: Drożdżyńska, M., Monticelli, P., Neilson, D. and Viscasillas, J. (2016), Ultrasound-guided subcostal oblique transversus abdominis plane block in canine cadavers. Vet Anaesth Analg. doi:10.1111/vaa.12391 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. The full details of the published version of the article are as follows:  TITLE: Ultrasound-guided subcostal oblique transversus abdominis plane block in canine cadavers AUTHORS: Drożdżyńska, M., Monticelli, P., Neilson, D. and Viscasillas, J. JOURNAL TITLE: Veterinary Anaesthesia and Analgesia PUBLISHER: Wiley PUBLICATION DATE: 27 May 2016 (online) DOI: 10.1111/vaa.12391   SHORT COMMUNICATION Ultrasound-guided subcostal oblique transversus abdominis plane (TAP) block in canine cadavers Maja Drożdżyńska, Paolo Monticelli, David Nelson & Jaime Viscasillas Royal Veterinary College, Queen Mother Hospital for Animals, Hatfield, Hertfordshire, UK Correspondence: Maja Drożdżyńska, Hawkshead Lane, North Mymms Hertfordshire, AL9 7TA, E-mail: mdrozdzynska@rvc.ac.uk    Running Head: Subcostal TAP block in canine cadavers   1   Abstract 2 Objectives To describe the ultrasound-guided transversus abdominis plane (TAP) block using a 3 subcostal oblique approach in dog cadavers and to evaluate the spread of a methylene blue 4 solution using a multiple-injectiontechnique. 5 Study design Prospective, descriptive, experimental anatomical study. 6 Animal population Nine adult Beagle cadavers weighing 13 ±2 kg (mean ± standard deviation) 7 Methods Methylene blue solution (10 mL) was injected bilaterally within the fascia that overlies 8 the transversus abdominis muscle of dog cadavers under ultrasound guidance. For each side, a 9 total of 3 injections (3.3 ml each) were performed by the same operator. Dissection was 10 performed by a second operator 20 minutes later. Successful nerve staining was defined as the 11 presence of dye on the nerve with a length greater than 1 cm. 12 Results Ventral branches of T9, T10, T11, T12 and T13 nerves innervating the cranial abdominal 13 wall were stained in 72%, 95%, 100%, 95% and 61% of cases, respectively. Ventral branches of 14 L1 and L2 innervating caudal abdominal wall were stained in only 33% and 11% of cases, 15 respectively. The dye was found only in the fascia between the transverses abdominis and the 16 internal oblique muscles. 17 Conclusions and clinical relevanceThe ultrasound-guided subcostal oblique TAP block 18 provided adequate staining of the sensory innervation of the cranial abdominal wall and for this 19 reason further studies are needed to evaluate efficacy of this technique to block the nociceptive 20 response in clinical situations. 21 KeywordsCranial abdomen, dogs,regional analgesia,subcostal oblique approach, TAP block, 22 ultrasound guidance. 23   24   Introduction 25 The canine abdominal wall is innervated cranially by the ventromedial branches of T11, T12, 26 T13 nerves andcaudally by L1, L2 and L3 nerves (Evans, 1993). The transversus abdominis 27 plane (TAP) block is a regional anaesthesia technique designed to desensitize the nerves 28 innervating abdominal muscles, abdominal subcutaneous tissue and parietal peritoneum. Local 29 anaesthetic must be administered in the fascia between the internal oblique and transversus 30 abdominis muscles where the ventral branches of the spinal nerves are located.  31 In human anaesthesia, several approaches for ultrasound (US)-guided TAP block have been 32 described, such as: subcostal oblique, mid-axillary and posterior approach (Carney at al.2011). 33 The anterior approach, also known as a subcostal oblique approach, was described by Hebbard 34 (Hebbard 2010). This technique was developed to block ventral branches of T9 to T12 nerves in 35 order to provide somatic analgesia for supraumbilical abdominal surgeries.  36 Several clinical studies have been conducted in human anaesthesia to evaluate the effectiveness 37 of the subcostal oblique approach (Milan et al.2011; Wu et al.2013) Its analgesic efficacy and 38 positive impact on postoperative opioid requirements have been proven during liver transplants 39 (Milan et al.2011) and radical gastrectomies (Wu et al 2013). 40 In veterinary anaesthesia, the posterior approach for US-guided TAP block was described in dog 41 cadavers (Schroeder et al. 2011; Bruggink et al. 2012). Its clinical application has also been 42 demonstrated in one case report in a Canadian lynx (Schroeder et al. 2010) and, with some 43 modification to the technique, in a case series of dogs undergoing surgery for mastectomy 44 (Portela et al. 2014). To the author’s knowledge, no studies describing US-guided subcostal TAP 45 block have been published in the veterinary literature. Thus, the objectives of the present study 46 were: 47 1) Describe an ultrasound-guided subcostal transversus abdominis plane block 48   technique in dogs. 49 2) Evaluating the spread of methylene blue and individual nerve staining. 50  51 Materials and methods 52 Nine thawed canine cadavers (13 ±2 kg) euthanized for reasons unrelated to the present study 53 were used. The project received ethical approval (URN 2015 1345) from the Royal Veterinary 54 College, London.  55 All sonographic procedures were performed by the same operator (first author) using an 56 ultrasound machine(S9v; Sonoscape, China) with a 25mm linear array transducer (10-6 MHz). 57 An 18 gauge, 68mm Quincke spinal needle (BD Needle, Madrid, Spain) was used. The needle 58 stylet was removed before starting the procedure. The needle was primed with methylene blue 59 (Methylthionium Chloride Injection 1% w/v, Martindale, UK) and remained attached to the 60 syringe while the block was performed.  61 With the cadavers in dorsal recumbency, the abdomen was clipped and spirit (surgical spirit, Vet-62 Way, UK) with ultrasound gel (Blue ultrasound gel, Henleys Medical, UK) was applied. The 63 transducer was placed initially in a transverse orientation, perpendicular to the linea alba just 64 caudal to the xiphoid process. With the transducer in this position, the following structures could 65 be identified: lineaalba, fat within the falciform ligament, part of the rectus abdominis muscle 66 and peritoneum.Rotating the probe by 10-15 degreeswith the marker located craniallyand 67 therefore positioning it parallel to the costal arch and obliqueto midline, allowed visualization of 68 the rectus abdominis muscle (RAM) and the transversus abdominis muscle (TAM). Further, a 69 characteristic sonographic triangle formed by the two hyperechoic linear structures of the 70 peritoneum (deep) and fascia of TAM (superficial) could be found (Figure 1). When these 71 structures were identified, the needle was inserted from the cranial aspect of the transducer, using 72   an in-plane technique, with a 20 ° angle, so that the tip was located in the fascial plane between 73 RAM and TAM. 74 Injection of a liquid within the fascia created a characteristic fluid pocket which opened up the 75 fascia while the volume of fluid increased (hydrodissection). Conversely, if the tip of the needle 76 was placed within the muscle tissue, then spread of the injectate was chaotic and non-uniform. 77 When the investigator was satisfied with the position of the needle, a volume of 3.3 mL of 78 methylene blue was injected. The needle was removed and the hydrodissected fascial plane was 79 followed caudolaterally using the ultrasound image to the point where the fluid pocket 80 terminated. The edge of the fluid pocket was the target for needle placement for the second 81 injection and a further 3.3mL was injected. This lateral tracking and injection was repeated once 82 more, so that a total volume of 10 mL was administered over three points.The same procedure 83 was performed on the contralateral side. 84 Twenty minutes after completion of the procedure, the second investigator(second 85 author)performed dissection of the hemiabdominal walls. Staining of T9 to L2 nerves was 86 assessed and recorded. The nerve was considered successfully stained when dye could be 87 detected over a length greater than 1 cm.  88  89 Results 90 Eighteen hemi-abdominal walls of nine adult beagle cadavers were scanned, injected and 91 dissected. The previously described sonographic landmarks required to perform TAP block using 92 this approach were identified in all hemispheres. In all cadavers dye was located only in the 93 transversus abdominal plane.  94 The most cranial spread of the dye was observed at the level of the T9 nerve which was 95 successfully stained in 72% of cases. T10, T11, T12 and T13 were successfully stained in 95% 96   %, 100%, 95% and 61% respectively.  L1 and L2 nerves were successfully stained in 33% and 97 11% of cases. 98  99 Discussion 100 The results of the present study show satisfactory spread of the dye in the cranial abdominal wall 101 using an ultrasound-guided oblique subcostal approach. Similarly to human studies (Barrington 102 et al 2009),  the most cranial distribution of the dye in this approach was reported at the level of 103 the ninth intercostal nerve which, in the current study, was stained in 72% of cases. The success 104 rate of T9 to T13 nerve staining suggests that this technique could be suitable for treatment of 105 somatic pain associated with procedures performed in the cranial abdomen such asliver surgeries 106 (lobectomy, portosystemic shunt occlusion, cholecystectomy), gastrotomy and splenectomy. 107 Nerves L1 and L2 were blocked in less than one-third of the cases. One possible explanation for 108 the lower success rate may be that the volume of dye injected was too small to spread far enough 109 caudally. However, conflicting information regarding the influence of volume on dye spread is 110 found in the literature. Carney et al. (2011) showed in a human study that doubling the volume of 111 solution did not result in more extensive dye spread and that injection site rather than the volume 112 is more important in determining spread. Contrastingly, a positive correlation was found between 113 volume injected and dye spread in dogs (Bruggink et al 2011).Therefore, it is possible that in the 114 present study, caudal abdominal nerves (L1, L2) could have been stained with a higher success 115 rate if dye volume had been increased.  116 When we compared our datatothe Schroeder et al. study (2011), which investigated dye spread 117 after posterior TAP approach in canine cadavers, the success rate in staining particular nerveswas 118 significantly different between the posterior and subcostal oblique approaches. First, the most 119 cranial spread of dye in Schroeder´s study was to the level of T11 which was stained in only 20% 120   of cases, whereas T11 was stained in 100% of cases using the subcostal approach. Furthermore, a 121 more cranial spread of the dye was achieved in our study- T9 and T10 nerves were stained in 122 72% and 95% respectively whereas neither of these nerves were stained using the posterior 123 approach. However, Schroeder et al. had a higher success rate and better spread of dye in the 124 caudal abdomen- T13, L1 and L2 were stained in 100%, 90% and 30% of cases respectively, 125 compared to this study where success rate was 61%, 33% and 11% respectively. Based on these 126 findings, we can postulate that combining the posterior approach described by Schroeder et al. 127 and the subcostal approach described here may be a reasonable option for long abdominal 128 incisions extending from the pre-umbilical to the caudal abdominal region. Portela et al. (2014) 129 who first described the clinical application of posterior TAP block for radical mastectomy in 130 dogs, used two injection sites: cranial to the iliac crest and caudal to the last rib.  It is difficult to 131 reach a clear conclusion regarding the cranial extension of this TAP block since intercostal 132 blocks were performed concurrently in order to block the most cranial mammary glands. 133 The injectatevolume of 10 mL was based on the only known previously published veterinary 134 study (Schroeder at al. 2011) which allowed for comparison with our results. However in a 135 clinical scenario, the decision about injected volume will be influenced by two factors: toxic 136 dose and the final concentration of the local anaesthetic solution.One must first consider that the 137 toxic dose should not be exceeded, and second that the local anaesthetic shouldnot be diluted 138 below its minimumeffective concentration because sensory block may not be achieved.  139 Further clinical studies are needed in veterinary anaesthesia to determine the peak plasma 140 concentration of local anaesthetics following administration for TAP block and to determine the 141 minimum dose needed to achieve satisfactory analgesia. 142 The distribution of the dye in cadavers may not reflect exactly the final distribution of the local 143 anaesthetics in clinical cases. Carney (2011) found that in humans the spread of local 144 anaesthetics within the fascia is time-dependent (Carney at al.2011). Although this information is 145   not as applicable to the cadaveric study, it may have significant impact on clinical efficacy of the 146 block depending on the time elapsed between performing the block and starting the surgical 147 procedure. 148 In conclusion, US-guided subcostal TAP block may provide somatic analgesia of the cranial 149 abdominal wall in dogs. Clinical studies are needed to evaluate the efficacy of this block in 150 providing perioperative analgesia for patients undergoing cranial abdominal surgery. 151 Acknowledgements 152 Authors’  contributions 153 MD: performed the US-guided TAP blocks, literature overview, manuscript preparation; PM: performed 154 the cadaver dissection and assessment of dye spread, data collection and analysis; DN: manuscript 155 preparation, language corrections; JV: idea provider, teacher, supervisor, manuscript preparation. 156  157  158 References 159 Bruggink SM, Schroeder KM, Baker-Herman TL et al. (2012) Weight-based volume of injection 160 influences cranial to caudal spread of local anesthetic solution in ultrasound-guided transversus 161 abdominis plane blocks in canine cadavers. Vet Surg 41, 455-457. 162 Carney J, Finnerty O, Rauf J et al. (2011) Studies on the spread of local anaesthetic solutions in 163 transversus abdominis plane blocks. Anaesthesia 66, 1023-1030. 164 De Oliveira Gildasio S, Castro-Alves, Jorge L et al. (2014) Transversus Abdominis Plane Block 165 to Ameliorate Postoperative Pain Outcomes After Laparoscopic Surgery: A Meta-Analysis of 166 Randomized Controlled Trials. AnesthAnalg 118, 454-463. 167 Evans HE (1993) Miller’s Anatomy of the Dog (3rd edn).Saunders, Philadelphia, PA. pp. 308–168   312 169 Hebbard P (2008) Subcostal Transversus Abdominis Plane Block Under Ultrasound Guidance. 170 AnesthAnalg 106, 674-675. 171 Milan ZB, Duncan B, Revari V et al. (2011) Subcostal Transversus Abdominis Plane Block for 172 Postoperative Analgesia in Liver Transplant Recipients. Transplant Proc 43, 2687-2690. 173 Portela DA, Romano M, Briganti A (2014) Retrospective clinical evaluation of ultrasound 174 guided transverse abdominis plane block in dogs undergoing mastectomy. Vet AnaesthAnalg 41, 175 319-324. 176 Schroeder CA, Schroeder KM, Johnson RA (2010) Transversus abdominis plane block for 177 exploratory laparotomy in a Canadian lynx (Lynx canadensis). J Zoo Wildl Med 41, 338-341. 178 Schroeder CA, Snyder LBC, Tearney CC et al. (2011) Ultrasound-guided transversus abdominis 179 plane block in the dog: an anatomical evaluation. Vet AnaesthAnalg 38, 267-271. 180 Wu Y, Liu F, Tang H et al. (2013) The analgesic Efficacy of Subcostal Transversus Abdominis 181 Plane Block Compared with Thoracic Epidural Analgesia ad Intravenous Opioid Analgesia After 182 Radical Gastrectomy. AnesthAnalg 117, 507-513. 183   184   Figure Legend 185 SCT- subcutaneous tissue, RAM- rectus abdominis muscle, F-fascia of the transversus abdominis 186 muscle, TAM- transversus abdominis muscle, P- peritoneum. 187  188 

Ultrasound-guided subcostal oblique transversus abdominis plane block in canine cadavers

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