A couple of weeks ago I was on OB, I was called to assess the discomfort patient experienced in her perineal area. Patient was in early stage of labor, 4cm dilated and had epidural in place. Patient had a good bilateral sensory block, suggesting that the epidural was working well. As we know, labor epidural catheter may not adequately bathe and penetrate the sacral plexus to provide relief. I ended up doing a CSE and patient got comfortable. CSE is not something I do on a regular basis, and it appears to have its unique niche in OB anesthesia.
CSE can minimize the sacral sparing phenomenon as the intrathecal local anesthetic directly bathes the sacral nerve roots in the cauda equina. If given opioid, it directly binds the mu-opioid receptors of the substantia gelatinosa in the spinal cord. Hence, the onset of relief is faster with great sacral coverage. So it is important to be proficient in CSE’s. The following are some practical points that may help in placing and managing them.
Some people may argue it increases PDPH and you may not able to test the function of epidural right away. This retrospective study below demonstrated that the placement of CSE did not necessarily delay the recognition of failure of epidural.
1). Quick onset, less than 5 minutes.
2). Less top-ups with the intrathecal spread of the local epidural anesthetic.
3). More bilateral blocks. Less anesthesia time spent in top-ups and patient care.
4). Greater patient satisfaction scores.
5). Less leg numbness and more leg movement in the first hour of the CSE.
6). A verification (CSF) that the epidural catheter will be going in the epidural space.
7). CSE’s are great for a multiparous patient who is dilating fast. You get great pain relief without the extreme numbness of a heavy CLE.
8). CSE’s can be used for a C/S that may be complicated or have an anticipated longer surgical time.
1). A slightly longer set up time with the addition of 3 items to the tray. A slightly longer needle insertion time in the back.
2). A potential increase in a PDPH from a pencil point spinal needle though very rare.
3). A slightly increased potential risk of infection in the CSF but preventable with sterile technique and dress codes.
Dosing the CSE: For laboring patients. The standard intrathecal dose is: 1 ml 0.25% Marcaine with or without 15 mcg fentanyl. In multiparous patients who are in a very active and progressing labor pattern, the dose can be increased to 1.2 ml 0.25 % Marcaine plus the Fentanyl 15 mcg. For patients in early labor 0.6-0.8ml 0.25% marcaine and 15 mcg of Fentanyl. For patients less than 3cm dilation, fentanyl alone often suffices.
It is rare to see the dermatome level go too high or too low. Sitting patients up at about a 45% semi-fowlers position for the first 30+ minutes if possible to avoid potential hypotension.
A test dose can be done once the patient is lying back in bed. Patients should still be able to move their legs and toes. A positive test dose there would exhibit as a change in block intensity, where little or no leg movement would be seen. The intravascular injection part of the test dose does not change.
An epidural loading dose of local anesthetic is generally not needed unless the intrathecal injection did not produce an adequate block. If the intrathecal block is adequate, just start the PCEA pump without loading dose, and by the time the spinal meds wear off, there is enough local anesthetics to have an adequate epidural block. Administering a normal epidural loading dose may result in a very dense block, inability to push, and a high dermatome level. If needed to supplement the intrathecal block, A 2 – 5 ml dose of local anesthetic is plenty.
Pump infusion rates of the CLE: Since there is an conduit between intrathecal and epidural space, the local anesthetic diffuses intrathecally due to concentration gradient, the pump rate needs to be reduced. 8 ml / hour is usually adequate for most of the patients. The epidural top up dose is the same as a regular epidural catheter top up dose.
Technique. Use the CSE needle kits as they are designed to work better. The kits include the 17Ga CSE kit with the 25 Ga Whitacre high flow needle. If your facility doesn’t have the CSE kit, you can substitute with a 6 inch long spinal needle through the tray epidural needle. When placing the epidural needle, use as little saline for the “loss of resistance” as possible. This keeps the dura closer to the epidural needle. Loss of resistance with air, if inadvertently injected intrathecally can be problematic. Once you feel loss of resistance with the epidural needle, slide the spinal needle down until you feel the resistance. You may only dent the dura not pierce it if you advance too slowly. Dural pop may not be felt with the spinal needle possibly due to the drag between the two needles.
It is likely to observe about 10% of the incidence of paresthesias with CSE’s than with SAB blocks. It It could come from bumping the nerves in the spinal/subdural and is usually mild in nature. The other paresthesia may result from the needle bumping the nerve root outside the dura when off midline.
OR placement of CSE for a potentially lengthy C/S:
The placement technique of the CSE is the same. The spinal dosage for a CSE is the same as a normal C/S spinal. The Duramorph and fentanyl can be placed in the spinal meds (preferred) or given in the CLE if indicated. The onset of the dense block is rapid and you will need to move quickly to place and secure the epidural catheter before the SAB block settles. Dosing the CLE block is similar to dosing a labor epidural for C/S. The volume in the CLE may need to be reduced due to the intrathecal spread.
Labor CSE, now going for a C/S:
Use the standard CLE dose of local anesthetics as well as fentanyl and duramorph if allowed. The CSE provides more solid block for a C/S.
I hope this information is helpful for your OB practice.