8/11/2019 Stain distribution of a lidocaine-methylene blue solution in saphenous, obturator and lateral femoral cutaneous ne

1/1

Stain distribution of a lidocaine-methylene blue solution in saphenous, obturator

and lateral femoral cutaneous nerve blocks

employing superficial anatomical landmark-based techniques in the dog

DF Echeverry1, JT Pelez1, EF Buritic1& FG Laredo 2

1Faculty of Veterinary Medicine and Zootechny, Tolima University, Ibagu, Colombia2Faculty of Veterinary Medicine, Murcia University, Spain

Introduction:

The benefits of ultrasound and nerve stimulation to guide peripheral nerve block have been described in dogs (Echeverry et al.

2010). However there are some factors that could limit the use of these techniques (Saranteas et al. 2008). This study evaluated

the distribution of a lidocaine-methylene blue staining solution in saphenous (SN), obturator (ON) and lateral femoral cutaneous

(LFCN) nerve blocks employing superficial anatomical landmarks (SLM) based techniques in dog cadavers.

Figure 1. Superficial anatomical landmarks and location of theneedle and the for the injection of the staining solutions in the periphery of: A. Saphenous

nerve; B.Obturator nerve; C.Lateral femoral cutaneous nerve. Cr= cranial, Cd= caudal, Med= medial, Dor= dorsal, Ven= ventral, Fa= Femoral artery, Pm=

Pectineous muscle, Pm*= Pectineous musclesorigin, Am= Adductor muscle, Icr=Iliac crest, the index finger is in contact with the transverse process of theseventh lumbar vertebra..

Results & conclusions The techniques employed were effective to produce an adequate distribution of the staining solution over the 100% of the

studied nerves when using 0.2 (ON,LFCN) or 0.3 (SN) mL.Kg-1 of staining solution. There was no gross evidence of

intraneural injection in any case.

This study shows potentially useful techniques based on anatomical SLM to perform the anaesthetic blockade of the SN, ON

and LFCN nerves.

References Echeverry DF, Gil F, Laredo F et al. (2010) Ultrasound-guided block of the sciatic and femoral nerves in dogs: a

descriptive study. Vet J 186, 210 - 215.

Saranteas T, Karakitsos D, Alevizou A et al. (2008) Limitations and technical considerations of ultrasound-guided

peripheralnerve blocks: edema and subcutaneous air. Reg Anesth Pain Med 33, 353 - 356.

Dolan J, Williams A, Murney E et al. (2008) Ultrasound-guided fascia iliaca block: a comparison with the loss of

resistance technique. Reg Anesth Pain Med 33, 526-531.

Materials & Methods:

Fifteen fresh dog cadavers weighing 10-30 Kg were randomly assigned to 3 groups of 5 dogs each to receive perineurally a

mixture of 2% lidocaine and 2% methylene blue (50% v/v) at doses of 0.1, 0.2 or 0.3 mL kg-1. The injections were performed

using an insulated needle (50 mm x 22 G) for the SN and a hypodermic needle (38mm x 21G) for the ON and LFCN. The SN was

approached at the femoral triangle using the femoral artery as SLM and employing a loss-of-resistance technique (Dolan et al.

2008). The ON was located within the fascial planes existing between the Pectineus and Adductor muscles and the LFCN

subcutaneously using the transverse process of the seventh lumbar vertebra as SLM. Necropsies were performed 15 minutes

after the injections. A staining length 2 cm along the target nerve was considered as an adequate distribution of the solution.

Cr

penis

Med

Cd

Cd Cr

Cd

Cr

Dor Ven

Fa

Fa

PmAm

Pm*

Icr *

*

Figure 2. Evaluation of this distribution of the stainig solution in the studied nerves: A. Saphenous nerve; B. Obturator nerve; C. Lateral femoral

cutaneous nerve. Cr= cranial, Cd= caudal, Dis= distal, Prx= proximal, FA= Femoral artery, FV= Femoral vein, FN= Femoral nerve, SN= Saphenous

nerve, Rm*= muscular branches of the FN for the Quadriceps muscle, Rm**=muscular branches of the FN for the Sartorious muscle, Pm= Pectineous

muscle, Adm= Adductor muscle, Gm= Gracilis muscle, SMc= Sartorious muscle (cranial part), RF= Rectus Femoris muscle, Sk= Skin (reflected), EAO=

External abdominal oblique muscle.

A B C

A B

SN

FA

FV

FN

Cr

Dis

Rm*

Rm**

Cr

Dis

Pm

Adm

CCr

Cd

Prx

Dis

EAO

SMc

RF

Sk

Gm

SkSk