Effect of cephaloid vs. caudally threaded labor epidural catheter in achieving adequate sensory block for normal delivery/caesarean section-a randomized control study

bor epidural analgesia is considered as the gold standard and is universally accepted. The pain during first stage of labor is due to uterine contraction and is referred to T10-L1 dermatomes. Pain during second stage of labor is due to stretching of perineum and referred to S2-4 nerve roots. Hence a block from T10 to S4 is required to provide adequate labor analgesia. If a cesarean section is required for these parturients, a block up to T6 is required. Despite widespread use, there are many uncertainties regarding the siting of epidural catheter. We hypothesized that cephaloid threaded labor epidural catheter will achieve sensory block up to T6 earlier than caudally threaded catheter whereas a caudally placed epidural will provide better analgesia during second stage of labor and episotomy. Thus we aimed to compare the effect of cephaloid vs. caudally threaded labour epidural catheter in achieving adequate sensory block in parturients.

Primary objective

Comparison of time taken to achieve sensory block up to T6 with cephaloid vs. caudally threaded labor epidural catheter for cesarean section

Secondary objectives are t oComparison between  two groups, requirement of additional boluses  for achieving adequate block for cesarean section and conversion to general anesthesia for cesarean section

Materials and Methods

After the approval of the Institutional Ethical Committee, informed consent from parturients and CTRI registration, this prospective, double‑blinded, randomized study will be conducted. Parturients between 18 and 40 years belonging to the American Society of Anesthesiologists (ASA) physical status Classes II and II1, with uncomplicated cephalic singleton pregnancy will be recruited. Patients in active labor and desirous of having a labor epidural will be randomly assigned to two groups by computer generated random sequence of numbers. Blinding will be achieved by closed envelope technique.

Exclusion criteria include any contraindication for epidural placement like bleeding disorders, decreased platelet counts, sepsis, spinal column deformities, history of spine surgery and hypersensitivity to study drugs, parturients requiring emergency cesarean under general anesthesia.

Pain will be assessed using visual analog scale (VAS) before placement of the epidural catheter. Parturients will be randomized into group CA or CE group. The catheter will be threaded caudal in CA and cephaloid in group CE. After attaching monitors and starting an intravenous line, the patient will be placed in sitting position and under aseptic precautions an epidural catheter will be placed by consultant anesthesiologist at L3–L4 interspace  using Portex Epidural minipack system 2 (manufacturer: Smiths Medical, Czech Republic). The catheter will be threaded caudal in CA and cephaloid  in group CE parturients, 5cm into the epidural space. Test dose will be avoided in all parturients as per institutional protocol.

Accidental intrathecal or intravascular placement of catheter will be ruled out by aspiration of the multi‑orifice catheter. If there is an accidental intrathecal or intravascular placement, the catheter will be re‑sited, and the patient will be removed from the study. The intermittent epidural bolus dose of 20mL of 0.1% ropivacaine with 40 µg fentanyl will be used as per institutional protocol. Same dose regimen will be repeated as subsequent top‑up dose on patients demand for pain relief or when the pain score is >4.

A second anesthesiologist who will be blinded to the technique will assess the adequacy of analgesia after 20 minutes. Analgesia will be considered adequate if the pain score is <4. If adequate analgesia was not achieved even after 20 min, an additional 10 mL of 0.1% ropivacaine will be administered, and analgesia will be reassessed. If pain relief is inadequate, the epidural analgesia will considered as epidural failure, and parturient will be excluded from the study.

The presence of motor block in the lower extremities will be assessed using a Breen modified Bromage scale (Grade 1 as complete motor block to Grade 6 as no motor block). The pain score will be assessed 20 minutes after each bolus and the stage of labor will be noted. Pain score will be noted during episiotomy.

If these parturients are posted for cesarean section, they will be shifted to OR. Patient will be coloaded with 10mL/kg of Ringer lactate. Standard monitors will be connected and a test dose of 3mL of 2% lignocaine with adrenaline will be given to rule out intrathecal or intravascular migration of catheter. Following this 10mL 2% lignocaine with adrenaline + 50µg fentanyl +1mL sodium bicarbonate (total 12mL) will be given as aliquots. Time taken to achieve sensory block up to T6 will be noted. Additional doses required for achieving block up to T4 and conversion to general anesthesia due to failure to achieve adequate block will be noted.