Obstetric Anesthesia179 Local anesthetics are frequently added to PCEA for post-cesarean analgesia.
The concentration of local anesthetic must be low to avoid signifi -
•
cant sensory or motor blockade, as many patients are ambulatory within hours of surgery.
A concentration of bupivacaine as low as 0.03
• % has been reported
to interfere with ambulation when used in combination with fentanyl or buprenorphine.
A concentration of bupivacaine 0.01
• % does not interfere with
ambulation, but epidural fentanyl consumption is comparable to PCEA fentanyl without added bupivacaine.
It is unclear what benefi t, if any, including dilute bupivacaine in a
•
PCEA solution provides.
Other Adjuncts for PCEA
Clonidine and epinephrine (which both presumably activate α -2 adrenergic receptors) and neostigmine (which prevents the break- down of synaptically released Ach) have also been used with PCEA.
When combined with sufentanil PCEA, both epinephrine and cloni-
•
dine signifi cantly reduce epidural opioid use.
Clonidine causes signifi cant decreases in blood pressure and heart
• rate.
Neostigmine, even at very low doses, signifi cantly increases nausea
•
and vomiting.
Neither clonidine or neostigmine can be recommended for routine
•
use with PCEA.
PCEA can be an effective technique for post-cesarean analgesia.
Whether it offers distinct advantages over epidural or intrathecal mor- phine is a matter of dispute. A disadvantage is the necessity to maintain a functioning epidural catheter in the postoperative period. Further, in many practices cesarean delivery is likely to performed with a single-shot spinal anesthetic technique, without an epidural catheter inserted. PCEA remains a useful technique for selected patients and populations.
180Post-Cesarean Analgesia
While in some situations NSAIDs can decrease postoperative opioid use, at this point it is diffi cult to make a blanket recommenda- tion for their use. Nevertheless, nonsteroidal agents (NSAIDs) may be of value in this population.
Many patients who have had a cesarean delivery remain NPO for
•
some period of time following delivery; during this period, a parenteral alternative to oral medications may be necessary.
While unrestricted oral intake may not resume for up to 24 hours
•
after delivery, many parturients are able to tolerate small amounts of fl uids, and can take an oral NSAID as an adjunct to neuraxial or parenteral analgesics.
A number of NSAIDs have been used in the post-cesarean period.
Various NSAIDs may be administered via the intravenous, intramuscu- lar, or rectal routes.
Ketorolac 30 mg IM is roughly comparable to meperidine 75 mg IM,
•
but ketorolac is somewhat inconsistent and of short duration.
Ketorolac has also been administered IV on a scheduled basis after cesarean delivery with mixed results.
When administered via continuous intravenous infusion, diclofenac
•
or ketoprofen decrease postoperative analgesic requirements by about 40 % when compared to placebo.
Propoacetamol is widely used in some parts of the world via rectal
•
administration following cesarean delivery.
In general, the drawbacks to the use of an NSAID in conjunction with intrathecal or epidural opioids are minimal. When used, they should be administered on a scheduled basis rather than PRN (“as needed”) dosing. The anesthesiologist must remain aware that while potentially helpful, NSAIDs will be ineffective adjuncts for many patients, and alternative therapy will be necessary.
Other Oral Agents
Tramadol is a synthetic 4-phenyl-piperidine analogue of codeine, which has a low affi nity for mu opioid receptor. It inhibits serotonin and nore- pinephrine neuronal reuptake. Reported use as an oral analgesic in the post-cesarean population has been very limited, but it has been used as a “rescue” analgesic in combination with other analgesic modalities, or as an alternative to an oral opioid if a parturient is intolerant.
A 25mg dose can be administered every 4 to 6 hours.
•
Tramadol should probably be avoided in patients with seizure dis-
•
orders or severe preeclampsia, as it has been shown to decrease seizure threshold.
Obstetric Anesthesia181 Further Reading
1. Cohen SE , Desai JB , Ratner EF , et al . Ketorolac and spinal morphine for postcesarean analgesia . Int J Obstet Anesth. 1996 ; 5 : 14 - 18 .
2. Eisenach JC , Grice SC , Dewan , DM . Patient-controlled analgesia following cesarean section: A comparison with epidural and intramuscular narcotics .
Anesthesiology. 1988 ; 68 : 444 - 448 .
3. Gourlay GK , Cherry DA , Cousins MJ . Cephalad migration of morphine in CSF following lumbar epidural administration in patients with cancer pain .
Pain . 1985 ; 23 : 317 - 326 .
4. Helbo-Hansen HS , Bang U , Lindholm P , et al. Maternal effects of adding epidural fentanyl to 0.5 % bupivacaine for caesarean section . Int J Obstet Anesth. 1993 ; 2 : 21 - 26 .
5. McDonnell NJ , Keating ML , Muchatuta NA , et al. Analgesia after caesarean delivery . Anaesth Intensive Care 2009 ; 37 : 539 - 551 .
6. Paech MJ , Moore JS , Evans SF . Meperidine for patient-controlled analgesia after cesarean section . Anesthesiology . 1994 ; 80 : 1268 - 1276 .
7. Paech MJ , Pavy TJG , Orlikowski CEP , et al . Postoperative epidural infusion: a randomized, double-blind, dose-fi nding trial of clonidine in combination with bupivacaine and fentanyl . Anesth Analg. 1997 ; 84 : 1323 - 1328 .
8. Palmer CM . Continuous intrathecal sufentanil for postoperative analgesia .
Anesth Analg. 2001 ; 92 : 244 - 245 .
9. Palmer CM , Voulgaropoulos D , Alves D . Subarachnoid fentanyl augments lidocaine spinal anesthesia for cesarean delivery . Reg Anesth . 1995 ; 20(5) : 389 - 394 .
10. Palmer CM , Emerson S , Voulgaropoulos D , et al. Dose-response relationship of intrathecal morphine for post-cesarean analgesia .
Anesthesiology. 1999 ; 90 : 437 - 444 .
11. Palmer CM , Nogami WM , Van Maren G , et al. Post-cesarean epidural morphine: a dose response study . Anesth Analg. 2000 ; 90 : 887 - 891 . 12. Wang JK , Nauss LA , Thomas JE . Pain relief by intrathecally applied
morphine in man . Anesthesiology . 1979 ; 50 : 149 - 155 .