Influence of Body Positioning on the Identification of Tuffier's Line Using the Palpation Method: An Ultrasound Study

Study Overview
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Brief Summary
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The study aims to ascertain whether being placed in a sitting or lateral decubitus position, influences identification of the midpoint of the L4/L5 intervertebral space, using manual demarcation of Tuffier's line. Participants will be randomly assigned to a sitting or lateral decubitus position. The mid-point of the L4/L5 intervertebral space will be identified using anatomical palpation and compared to the true mid-point measured by ultrasound. The procedure will be repeated in both positions on the same participant.The study will be a prospective, randomized, double blinded, crossover trial

Detailed Description
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Anaesthetists insert epidurals or spinal anaesthetics (collectively called central neuraxial blocks) to patients during childbirth to provide pain relief and anaesthesia. A spinal anaesthetic involves the injection of pain relieving medicines directly into the sac of fluid that surrounds the spinal cord. An epidural uses a different technique to place a thin plastic tube into the fatty tissues that surround this sac. Spinal anaesthesia must be placed below where the spinal cord ends to avoid nerve trauma. Doctors have traditionally been taught to identify a safe level, by feeling the top of a patients hips and drawing an imaginary line between these two points across the patients back known as Tuffier's line. This identifies L4/5 interspace, below which anaesthetists avoids the termination of the spinal cord. The same blind anatomical rule is used throughout anaesthetics, whether the patient is male or female, young or old, pregnant or non-pregnant, supine or lateral, an approach that is clearly far from robust. The physiological changes of pregnancy such as fluid retention and weight gain can further make identification of the standard landmarks challenging. Advances in ultrasound technology have allowed direct visualisation of the bones in the back. Studies have shown that the conventional anatomical based method for locating the point of needle insertion is unreliable even amongst experienced anaesthetists. Spinal or epidural anaesthesia can be performed with the patient either sitting or lying on their side. The investigators aim to determine whether a difference exists between the perceived mid-point of the L4/L5 intervertebral space, identified using manual demarcation of Tuffier's line, in these two positions. Ultrasound will then be used to ascertain the distance from the true midpoint.

Official Title
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Influence of Body Positioning on the Identification of Tuffier's Line Using the Traditional Palpation Method: An Ultrasound Study.

Conditions
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Pregnant Women

Intervention / Treatment
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* Diagnostic Test: Ultrasound spine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: >37 weeks gestation BMI<40 Singleton pregnancy Aged 16 to 65 years old. Latent phase of labour (<4cm cervix dilatation). Exclusion Criteria: Previous spinal surgery Scoliosis Age<16 Patient unable to tolerate positions Degenerative disease of the spine Patient refusal or inability to provide informed consent Patient in established labour (i.e. >4cm cervical dilatation)

Ages Eligible for Study
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Minimum Age: 16 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Ultrasound Spine in sitting position<br>Participants will be assigned to a sitting decubitus position to identify the Tuffier's Line | Diagnostic Test: Ultrasound spine<br>* A ultrasound of the lumbar spine of each patient will be performed in both positions to identify vertebral levels<br>|
| Ultrasound Spine in lateral position<br>Participants will be assigned to a lateral decubitus position to identify the Tuffier's Line | Diagnostic Test: Ultrasound spine<br>* A ultrasound of the lumbar spine of each patient will be performed in both positions to identify vertebral levels<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Discrepancy in distance between palpation vs. ultrasound midpoint of L4/5. interspace. | Distance (mm) between the mid-point of the L4/L5 intervertebral space in sitting and lateral decubitus positions, identified through manual palpation compared to the true mid-point measured by ultrasound. | 15-30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Discrepancy in distance between ultrasound midpoint of L4/5 in sitting vs. lateral position | Distance (mm) between the mid-point of the L4/L5 intervertebral space identified by ultrasound in sitting versus lateral decubitus positions. | 15-30 minutes |