Aims

To determine the discrepancy between conventional landmark technique and Ultrasound to identify site of insertion of Lumbar CNB.

No patients should have their spinal/ CSE sited above the L2-3 interspace.

Introduction

Methods

Results

• Accuracy of landmark technique: 45.4%• Increased BMI & difficulty of palpation of landmarks

>> Statistically significant decrease on accuracy (p=0.0.32* & 0.019* respectively)

• 7 out of 68 (10.3%) patients had their spinal/CSE placed above L2 level

• No statistically significant correlation between the experience of operator & accuracy (p=0.311*)

* Fisher’s Exact t-Test (2-tailed)

Key Findings

Recommendations• All patients having a lumbar CNB should have

ultrasound of their spine to identify the correct vertebral level

• Easy availability of curvilinear probes• Promote staff education & awareness

References1. Shiraishi N, Matsumura G. What is the true location of Jacoby’s line?

Okajimas Folia Anat Jpn 2006; 82: 111–52. Render CA. The reproducibility of the iliac crest as a marker of lumbar

spine level. Anaesthesia 1996; 51: 1070–1

3. Halpern SH, Banerjee A, Stocche R, Glanc P. The use of ultrasound for lumbar spinous process identification: A pilot study. Can J Anaesth 2010; 57: 817–22

Ultrasound Analysis of the Accuracy of Landmark Approach to Central Neuraxial Blocks in Anaesthesia

Lie J1, Venkataraju A1, Bhatia K2 & Kochhar P2

1 Specialty Trainee in Anaesthesia, 2 Consultant Anaesthetist

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•Three experienced US operators retrospectively performed the US of spine post-operatively in 91 patients having a lumbar CNB by landmark method•From January to March 2013•Location: St Mary’s Hospital & Manchester Royal Infirmary•Patient’s demographics, anaesthetic details of CNB & documentation of CNB were noted, including vertebral level at which CNB was performed•US spine was then used to identify the actual vertebral level in which the block was performed at using the visible skin puncture point•Level was compared with documented vertebral level•Difficulty in palpating lumbar anatomy & iliac crest was also recorded

Specialty Number of PatientsObstetrics 51Orthopaedics 23Gynaecology 8Vascular 4Urology 3GI Surgery 2

Population Accuracy Spinal/ CSE above L2 % (n)

Overall 45.4% 10.2% (7)General 54.3% 16.2% (6)Obstetrics 39.2% 3.2% (1)

Block Level: USG Vs Documentation

Degree of Discrepancy

•Small sample size•Heterogeneous population - Obstetric/Non- obstetric, predominantly females•Skin puncture site & positioning•Operator bias

Limitations

•Correct identification of the vertebral level during a central neuraxial block (CNB) would avoid needle damage to the spinal cord which usually ends at L1-2 in adults•An imaginary horizontal line joining the posterior iliac crests (Tuffier’s line) is the most commonly used anatomical landmark by anaesthetists for CNB as it passes through the L4 vertebral body1, 2

•Evidence suggests that ultrasound (US) imaging of the spine by an experienced operator leads to correct identification of vertebral level in >90% of the patients3

69% (63) Spinal6% (5) CSE25% (23) Epidural

40.7% (37) of operators were consultants, followed by 29.7% (27) were senior trainees

91 patientsMedian age: 36 yrsMedian height: 164.5 cmMedian weight: 77 kgMedian Body Mass Index (BMI): 27.9 Kg.m-2