Ultrasound Guided Lower Limb Blocks Tony Allen

8/12/2019 Ultrasound Guided Lower Limb Blocks Tony Allen

1/39

Ultrasound guided lower limb blocksDr Anthony Allan

Great Western Hospital


2/39

Overview of lower limb nerve blocks

Femoral

Saphenous

Sciatic

Subgluteal approach

Popliteal approach

Tibial

Anatomy/sonoanatomy

Block conduct

Tips and clips


3/39

Lower limb ultrasound

general points

Pattern recognition + practice

Proximal fat distribution and block conduct variability in probe/needle choice


4/39

Femoral anatomy


5/39

Sonoanatomy of femoral nerve

Hyperechoeic honeycomb architecture

Suprainguinal - oval 67%, triangular 33%

Infrainguinal oval 95%, triangular 5%

Average 10 mm by 3 mm


6/39


7/39

Femoral nerve block

Patient Supine, leg laterally rotated

Probe High frequency placed transversely justbelow inguinal ligament

Needle Dependant on approach/depth, 50-100mm


8/39


9/39

US guided femoral block

Improves block onset time to 3:1 block

Improves quality of block

Ultrasound Nerve stimulator

Onset time 16+/- 14 min 27+/-16 min

3:1 Block 95% 85%

2:1 Block 0% 5%

No block 5% 10%


10/39

Tips

Variable distance from vessels

Splits into terminal branched 0-5cms belowinguinal ligament

If deep - IP approach - place nerve on oppositeside of screen to needle entry


11/39

Saphenous nerve

anatomy/sonoanatomy

Cutaneous branch of post div of femoral nerve

Leaves adductor canal to emerge betweensartorius and gracilis

Runs down medial aspect of leg with and

immediately posterior and slightly deep to greatsaphenous vein

Seen as small speckled nerve bundle


12/39


13/39

Saphenous nerve anatomy


14/39

Saphenous nerve block

Patient Supine, knee slightly flexed, legexternally rotated

Probe High frequency placed transversely overmedial aspect lower thigh

Needle 50mm


15/39


16/39

Tips

Can be v difficult to visualise

Perivascular inj around great saphenous vein atlevel of tibial tuberosity


17/39

Sciatic nerve blocksubgluteal

approach

Subgluteal space potential space Roof - Gluteus maximus then biceps

Floor - Gemellus superior, obturator internus,

gemellus inferior, quadratus femoris, adductormagnus

Contains Sciatic and Post cut nerve of thigh

Inferior gluteal A+V


18/39


19/39


20/39

Sonoanatomy

Flat/oval hyperechoeic band

Up to 1.5-3cms wide

May see post cut nerve of thigh


21/39


22/39

Sciatic nerve blocksubgluteal

approach

Patient - Lateral, hips and knees flexed

Probe low frequency, sector array placedtransversely at level of line dividing greater

trochanter + ischial tuberosity

Needle 100mm


23/39


24/39

Tips

Depth makes needle visualisation more difficult

? Better view distally below biceps (infragluteal)

Helpful to use in conjunction with NS


25/39

Sciatic nerve blockpopliteal

approach


26/39


approach


27/39

Sonoanatomy

1 large or 2 smaller nerve bundles under biceps

Tibial n larger, medially in front of pop v + a

Common peroneal n smaller, moves laterallyfollowing medial border of biceps to neck offibula, possible to see sural com branch


28/39


29/39


approach

Patient position prone or supine with kneeflexed

Probe Mid/high frequency, transverselyproximal to popliteal crease angled slightly

caudad

Needle 50/100 approach/depth dependant,


30/39


31/39

Tips

Plantar/dorsiflexion of foot seesaw sign

Separate tibial and common peroneal injections when

nerve divides proximally nerve v deep - allows more distal injection where nerve is

more superficial

If doing IP approach

consider true lateral approach

inject to deep surface first


32/39

Tibial nerve anatomy


33/39

Sonoanatomy

Structures visible from ant-posteriorTibia

Tendon of tibialis posterior

Tendon of flexor dig longus Post tibial a + vs

Flexor hal longus + soleus

Achilles tendonTibial nerve speckled appearance, may have

already divided


34/39


35/39


36/39

Tibial nerve block

Patient supine, legs crossed distally and extrotated

Probe high frequency placed transverse justabove medial malleolus

Needle 50mm


37/39


38/39
http://upload.wikimedia.org/wikipedia/commons/1/16/Gray834.svg


39/39

References

Marhofer P, Greher M, Kapral S. Ultrasound guidance inregional anaesthesia. Br J Anaesth 2005; 94: 7-17

Marhofer P, Schrogendorfer K, Koinig H et al. Ultrasonographicguidance improves sensory block and onset time of three in one

blocks. Anesth Analg 1997; 85: 854-7 Lundblad M, Kapral S, Marhofer P, Londqvist P. Ultrasound-

guided infrapateller nerve block in human volunteers: descriptionof a novel technique. Br J Anaesth 2006; 97: 710-14

Karmarker M, Kwok W, Ho A et al. Ultrasound-guided sciaticnerve block: description of a new approach at the subglutealspace. Br J Anaesth 2007; 98: 390-5

Documents

Ultrasound Guided Lower Limb Blocks Tony Allen