Here is the full text content of the poster, slide by slide:

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SLIDE 1: TITLE AND BACKGROUND

Epidural Catheter Insertion to 4 cm versus 5 cm for Labour Analgesia: A Patient- and Assessor-Blinded Randomised Controlled Trial

W J Turner, F Wellner, N Siddiqui, K Downey, S Wang, M Balki Department of Anesthesia and Pain Management, Mount Sinai Hospital, University of Toronto

Background and Hypothesis

Labour epidural remains the gold standard for labour analgesia, but failure rates remain 10--20%. At the study institution, the rate of inadequate analgesia with 5 cm catheter insertion depth is approximately 20--40%. Insertion depth is a modifiable factor that varies widely. Shorter insertion carries a risk of dislodgement; deeper insertion carries a risk of coiling, unilateral block, and intravascular placement.

Objective: To evaluate the difference in quality of labour analgesia delivered by epidural catheters inserted to either 4 or 5 cm into the epidural space in women with BMI <40 kg/m².

Hypothesis: Insertion of epidural catheter to 4 cm depth would reduce the incidence of inadequate analgesia.

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SLIDE 2: METHODS

Study Design: Prospective RCT, patient- and assessor-blinded. Block randomisation, 1:1 allocation. Epidural with 17G Tuohy needle, 19G FlexTip Plus catheter, advanced to 15 cm then withdrawn to 4 cm or 5 cm; secured with LockIt Plus. Inserting anaesthetist unblinded; patient, assessors, and nurse blinded.

Loading dose: bupivacaine 0.125% + fentanyl 3.3 μg/mL (3 mL test dose + 12 mL). Maintenance: bupivacaine 0.0625% + fentanyl 2 μg/mL (PIEB 10 mL q40 min, PCEA 5 mL).

Participants: Labouring women ≥18 years, BMI <40 kg/m², cervical dilatation 3--7 cm. Exclusion: prior difficult or failed epidural, planned CSE or DPE.

Primary Outcome (Composite Inadequate Analgesia): VNRS >3 or block below T10 at any time; unilateral or patchy block; catheter manipulation or replacement; abandonment or conversion to alternative.

Secondary Outcomes: Hourly VNRS, block height, motor block, catheter events, top-ups, adverse events, fetal bradycardia.

Analysis: χ² or Fisher's exact test, R version 4.2.1. Sample size: n = 200 (80% power, α = 0.05), assuming composite outcome rate 25% in 5 cm group and 10% in 4 cm group.

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SLIDE 3: RESULTS

Consented n = 257. Analysed n = 193: 4 cm (n = 94), 5 cm (n = 99).

Table 1: Baseline Characteristics

Table 2: Epidural Performance and Clinical Outcomes

Absolute risk difference for primary outcome: -2.3% (95% CI -15.5% to 10.9%).

Hourly pain score trajectory: in both groups average VNRS scores remained generally low over time. The 4 cm group showed slightly higher mean VNRS (1.09 vs 0.70) and greater overall variability than the 5 cm group.

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SLIDE 4: DISCUSSION

Main Finding: In labouring women with BMI <40 kg/m², inserting epidural catheters to 4 cm or 5 cm produced similar rates of inadequate analgesia (35.1% vs 37.4%), catheter interventions, and adverse events. Clinician top-ups were required in 19% (37/193), catheter manipulation and re-insertion were each performed in 3% (6/193), and epidural catheters were successfully used in 94% (49/52) of caesarean sections. All secondary outcomes were similar across the two groups.

Clinical Implications: Small differences within the 4--5 cm range have limited impact on inadequate analgesia when using modern techniques (PIEB + PCEA) in patients with BMI <40 kg/m². This supports flexible, individualised depth selection in clinical practice. A high overall rate of inadequate analgesia (approximately 36%) suggests that other factors -- including patient anatomy, physiology, labour progress, epidural technique, and dosing regimen -- may also play a substantial role.

Limitations: Single-centre study; BMI <40 kg/m² only; inserting anaesthetist unblinded; findings may not be generalisable to different epidural regimens.

Future Directions: Multicentre study; evaluation of catheter depth in women with BMI ≥40 kg/m²; imaging studies of catheter trajectory; modification of epidural technique or drug regimens; use of a robust composite endpoint for future work.

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