///2015 Abstract Details
2015 Abstract Details2019-08-02T16:54:43-06:00

Neuraxial Ultrasound to Assess Midline Epidural Placement and Related Clinical Efficacy

Abstract Number: T-13
Abstract Type: Original Research

Carolyn F Weiniger MB ChB1 ; Rachel R Wang MD2; Benjamin Cobb MD3; Brendan Carvalho MBBS4

Introduction: Labor epidural analgesia (LEA) has a reported failure rate of 1.7-19.8%,(1) and identification of the midline for neuraxial anesthesia is important.(2) Ultrasound (US) has been shown to accurately assess the depth of the epidural space.(3) We hypothesized that US may be a useful tool to identify midline and that midline insertion improves LEA efficacy.

Methods: Fifty healthy women who received LEA inserted with landmark technique were approached immediately after delivery for this prospective cohort, IRB approved study. Prior to removing the epidural, we evaluated midline using US (UM), and measured the distance from UM to clinician midline (CM); the catheter inserted point. We also asked patients to self-identify their midline (PM) (assessed with pinprick in 1 mm increments) and measured the distance from UM to PM. LEA efficacy measures were average visual analogue score (VAS) for pain during stage 1 of labor, patient-controlled epidural analgesia (PCEA) pump demands and physician requested boluses. Data are described as mean±SD, median(IQR) and n(%). Bland-Altman analysis assessed US, clinician and patient self-identified midline distances, and correlations between UM-CM distance and block efficacy were performed.

Results: Our interim analysis cohort of 24 women aged 29±6, weighed 78±20 kg had parity 0(0-1). Bland-Altman analysis revealed that UM-CM distance was similar to the UM-PM distance, Figure. There were no significant correlations between UM-CM distance and PCEA demands (R=0.31, p=0.14), pain VAS (R=0.03, p=0.88) and physician bolus requirements (R=0.16, p=0.46).

Conclusions: In our low risk, non-obese laboring population, clinicians and patients reliably identified the midline, as confirmed by US assessment. Our interim results confirm the utility of patient’s self-identified assessment of midline.(4) This ongoing study will further assess relationship of LEA block insertion midline deviation and analgesic failures in obese and non-obese parturients.

References: 1) Carvalho B. Int J Obstet Anesth 2012;21:357. 2) Wills JS. Anaesthesia 2002;57:390-4.

3) Sahota JS. Anesth Analg 2013: 116:829. 4) Marroquin BM. J Clin Anesth 2011; 23, 3.

SOAP 2015