Efficacy of Pre-procedural Ultrasound of Lumbar spine in improving the procedural skill

of Subarachnoid block

Investigator – Dr. Arthi1st year PG, Department of Anaesthesiology

Guide : Dr. V Hemanth KumarProfessor in Anaesthesiology, MGMCRICo Guides : Dr. Archana Areti, Senior Resident in Anaesthesiology, MGMCRICo Guides : Dr. Jaya Assisstant Professor in Anaesthesiology, MGMCRI

Introduction• Spinal anaesthesia is the commonest procedure performed,

requiring adequate knowledge of the anatomy and orientation of central neuraxis, for performance of a successful block (in a single attempt).

• Traditionally landmark procedure is practised, with high incidence of multiple attempts causing patients distress and complications (e.g hematoma, post dural puncture headache)

• We wanted to investigate the use of USG as a tool for identification of the normal anatomy, to improve the technique of lumbar puncture for spinal anaesthesia.

Review of literature1. Levy JH et al conducted a retrospective study of the incidence and

causes of failed spinal anaesthetics in a university hospital. They found a 17% incidence of spinal failure.

2. Weed JT et al evaluated the use of pre-procedure ultrasound examination as a screening tool for difficult spinal anaesthesia. They concluded that, ultrasound represents an additional technology at our disposal.

Aims and ObjectivesAIM : To evaluate the efficacy of Pre-procedural Ultrasound of Lumbar spine in improving the procedural skill of Subarachnoid block

Primary objective – Incidence of procedural success within first needle pass

Secondary objectives– Number of passes to achieve CSF flow– Number of attempts– Time taken for procedure– Incidence of failure

HypothesisPre-procedural Ultrasound of Lumbar spine improves the procedural skill of Subarachnoid block.

Criteria for patient recruitment

Inclusion Criteria

• Patient refusal• Contraindication for spinal

anaesthesia e.g coagulopathy, local skin infection, allergy to LA

• Spinal deformity e.g scoliosis• BMI - >35 kg/m2, • Pregnancy• Previous spine surgery

Exclusion criteria

• Patients scheduled for surgery SAB

• Age above 18 years• ASA grade I - II

MET

HODO

LOGY

Approval from ethics committee

o 200 patients will be recruited by continuous sampling after satisfying criteria for selection. Informed consent will be obtained.

o All performers of the SAB, will be given a teaching module on anatomy of spine, lumbar anatomy and basics of spine scan .

o On day of surgery, patients shifted to procedure room o Patient in either sitting/lateral position, will be randomised into 2 groups,

by sealed envelope technique.

o In both groups markings will be made on the back of the patient with a skin marker, by the performer of the SAB

Group L – Landmark based Group U – USG based

• Subarachnoid block procedure in the OT, according to institutional protocol, after following a pre procedure checklist.

• Patients in either sitting/lateral position at L2/3 or L3/4 Spinal space with 25 G Quinke tip needle

Consultant will assess the performance of the SAB

GROUP L - Landmark based techniquePatients landmarks will be identified by palpatory method, with Tuffier’s line (intercrestal line) as a reference.1. The Spinous process will be identified and

marked from L1 to L5, with reference to Tuffier’s line.

2. Midpoint of Widest space is markedL1L2L3L4

x

Midpoint

GROUP U - USG based techniqueSonosite X porte ultrasound system, low frequency curvilinear probe C60 (2-5Hz), is used to scan in both transverse and sagittal planes. 1. The spinous processes are identified and marked.2. The midpoint of the maximum interspinous space.3. Maximum interlaminar space 4. Approximate depth

L1L2

L3L4

x

Maximum interlaminar space

Transverse spinous process scan

Identifies midline

Identifies depth

Posterior dura complex

Subarachnoid space

Tip of spinous process

S1L4 L5

Identifies space

Identifies interlaminar space

Median sagittal scan

SacrumL5

L5-S1 space

Study Parameters1. Incidence of procedural success within first needle pass – CSF detection

within the first needle pass.2. Number of needle passes by the performer – defined as the number of

forward advancements of the spinal needle in a given interspinous space, i.e., withdrawal and redirection of spinal needle without exiting the skin

3. The number of attempts - defined as the number of times the spinal needle is withdrawn from the skin and reinserted.

4. The time taken to detect CSF – time from first needle insertion till CSF detection.

5. Incidence of procedural failure – failure defined as more than 3 attempts. Rescue measure – A Consultant will perform the procedure.

• Levy et al reported a failure rate for landmark based spinal anaesthesia – 17%

• To reduce this incidence to 4%, with alpha of 0.05 and beta 80%, we calculated sample size, using formula given below, to be 87 per group.

• Considering drop out we took sample size to be 100 patients.

Sample size

Statistical analysis

• Study Involving geriatric age group.

Study parameter Statistical test

Incidence of procedural success in first needle pass Chi Square test

Number of needle passes Chi square test

Number of attempts chi square test

Duration of procedure Student t test

Incidence procedure failure Chi Square test

• Observational study

• Mild discomfort as part of spinal anaesthesia which is standard of care anaesthesia technique

Ethical Issues