Patient-controlled epidural analgesia in labor: the addition of clonidine to bupivacaine-fentanyl

A comparison of fetomaternal outcome in PCEA using fentanyl, clonidine and dexmedetomidine as adjuvants with Ropivacaine in painless labor: a prospective, double blinded randomized study

Background: Patient controlled epidural analgesia has been associated with marked maternal satisfaction. Combination of local anesthetics with various adjuvants have been tried to ensure optimum analgesia with no or negligible fetomaternal side effects. Aim: To compare fentanyl, clonidine or dexmedetomidine as adjuvants with ropivacaine for labor epidural analgesia (LEA) using a PCEA pump with the objective to assess fetomaternal outcome in terms of analgesic effect, success rate of vaginal delivery, complications, neonatal APGAR score and maternal satisfaction. Materials and methods: Sixty full term laboring women received 10 ml 0.2% ropivacaine followed by continuous infusion of 0.1% ropivacaine with 2 μg/ml of either dexmedetomidine, fentanyl or clonidine respectively in Groups A, B, and C at 6 ml/hr. demand bolus setting was 2 ml with a lock out interval of 15 minutes. At full cervical dilatation another 10 ml bolus of respective solution were given. Parturients were monitored at 0, 10, 20, 30 min after giving 1st epidural bolus dose and then at 30 min interval for ongoing labor for pain relief (VAS), motor blockade (Bromage score), progress of labor (duration of 1st stage and 2nd stage), mode of delivery, fetal APGAR score (at 1 min and 5 min), vitals (HR, NIBP, RR, SpO2), overall patient satisfaction and complications. The statistical analysis was done both qualitatively (Fisher-exact test/Chi-square test) and quantitatively (one-way analysis of variance test with post-hoc intergroup comparisons using Bonferroni’s correction). Results: Onset of pain relief was earlier in fentanyl group, however after 1 h all three groups showed comparable pain relief (P>0.05). There was a significant reduction in HR in group C and B compared to group A (P<0.001) and MAP in group C compared to groups A and B. The motor- blocking potency was slightly higher in dexmedetomidine group, however no significant motor weakness observed in any parturient. Mean demand bolus need was more in group C compared to A and B (P<0.001). There was no significant difference in mode of delivery (either SVD or cesarean) in between the groups. There was not a single case of fetal distress and most of the parturients showed satisfactory response to PCEA. Conclusion: All three study drugs produced equipotent analgesia in combination with ropivacaine 0.1%. There was absolute pain relief without significant motor blockade or any increase in instrumentation/cesarean deliveries or any adverse fetal outcomes.

Low dose intrathecal clonidine and fentanyl added to hyperbaric bupivacaine prolongs analgesia in gynecological surgery

Background:

We undertook this study to ascertain if a small dose of clonidine (30 μg) when added to a bupivacaine-fentanyl mixture improves spinal analgesia, without producing side effects, as compared to a bupivacaine-fentanyl or a bupivacaine-clonidine mixture.

Materials and Methods:

In this prospective, randomized, double-blind study, 75 (American Society of Anesthesiologists) ASA grade I-II patients, aged between 45 and 65 years, who were scheduled for vaginal hysterectomy with pelvic floor repair or non-descent vaginal hysterectomy under spinal anesthesia were recruited. The patients received hyperbaric bupivacaine (2.3 ml) with fentanyl 15 μg (Group BF) or clonidine 30 μg (Group BC) or both fentanyl (15 μg) and clonidine (30 μg) (Group BCF). The total amount of intrathecal mixture was constant (2.8 ml) in all the groups. Duration of sensory, motor block and effective analgesia, hemodynamic profile, postoperative pain score and analgesic requirements were recorded.

Results:

The duration of effective analgesia, mean time till two-segment regression, and duration of sensory and motor block were significantly longer in group BCF as compared to group BC (P ~ 0.002), and in group BC as compared to group BF (P ~ 0.01). The incidence of intraoperative pain and requirement of postoperative analgesics in the first 24 hours was significantly more in group BF as compared to the other groups (P ~ 0.01). There was no difference in the hemodynamic profile between the groups.

Conclusion:

Low-dose clonidine (30 μg) when added to a bupivacaine-fentanyl mixture increased the duration of effective analgesia and the duration of sensory and motor block in gynecological surgery. The incidence of intraoperative pain and requirement of postoperative analgesics was significantly less when clonidine was added to intrathecal bupivacaine with or without fentanyl.

Intrathecal clonidine in the neonatal rat: dose-dependent analgesia and evaluation of spinal apoptosis and toxicity

BACKGROUND

Neuraxial clonidine is used for perioperative analgesia in children of all ages. Preclinical studies in the postnatal rat allow comparison of the relative toxicity and safety of spinal analgesics throughout postnatal development.

METHODS

Rat pups aged 3, 7, or 21 postnatal (P) days were briefly anesthetized for intrathecal injections of saline or clonidine. At each age, the maximum tolerated, antinociceptive (increased hindlimb mechanical withdrawal threshold) and antihyperalgesic (hindpaw carrageenan inflammation) doses were determined. Lumbar spinal cord sections were assessed for apoptosis and cell death (histology, activated caspase-3 immunohistochemistry, Fluoro-Jade C staining), histopathology (hematoxylin and eosin staining), and increased glial reactivity (microglial and astrocytic markers). P3 intrathecal ketamine sections served as positive controls. In additional groups, thermal latency and mechanical withdrawal threshold were measured at P35.

RESULTS

Intrathecal clonidine produces age- and dose-dependent analgesia in rat pups. Maximal doses of clonidine did not alter the degree or distribution of apoptosis or increase glial reactivity in the neonatal spinal cord. No spinal histopathology was seen 1 or 7 days after injection at any age. Intrathecal clonidine did not produce persistent changes in reflex sensitivity to mechanical or thermal stimuli at P35.

CONCLUSIONS

Intrathecal clonidine in the postnatal rat did not produce signs of spinal cord toxicity, even at doses much larger than required for analgesia. The therapeutic ratio (maximum tolerated dose/antihyperalgesic dose) was >300 at P3, >30 at P7, and >10 at P21. These data provide additional information to inform the clinical choice of spinal analgesic drug in early life.

Progress in analgesia for labor: focus on neuraxial blocks

Neuraxial analgesia is widely accepted as the most effective and the least depressant method of providing pain relief in labor. Over the last several decades neuraxial labor analgesia techniques and medications have progressed to the point now where they provide high quality pain relief with minimal side effects to both the mother and the fetus while maximizing the maternal autonomy possible for the parturient receiving neuraxial analgesia. The introduction of the combined spinal epidural technique for labor has allowed for the rapid onset of analgesia with minimal motor blockade, therefore allowing the comfortable parturient to ambulate. Patient-controlled epidural analgesia techniques have evolved to allow for more flexible analgesia that is tailored to the individual needs of the parturient and effective throughout the different phases of labor. Computer integrated systems have been studied to provide seamless analgesia from induction of neuraxial block to delivery. New adjuvant drugs that improve the effectiveness of neuraxial labor analgesia while decreasing the side effects that may occur due to high dose of a single drug are likely to be added to future labor analgesia practice. Bupivacaine still remains a popular choice of local anesthetic for labor analgesia. New local anesthetics with less cardiotoxicity have been introduced, but their cost effectiveness in the current labor analgesia practice has been questioned.

Neuraxial drug administration: a review of treatment options for anaesthesia and analgesia

Neuraxial drug administration describes techniques that deliver drugs in close proximity to the spinal cord, i.e. intrathecally into the CSF or epidurally into the fatty tissues surrounding the dura, by injection or infusion. This approach was initially developed in the form of spinal anaesthesia over 100 years ago. Since then, neuraxial drug administration has evolved and now includes a wide range of techniques to administer a large number of different drugs to provide anaesthesia, but also analgesia and treatment of spasticity in a variety of acute and chronic settings. This review concentrates on the pharmacological agents used and the clinical basis behind currently utilised approaches to neuraxial drug administration. With regard to local anaesthetics, the main focus is on the development of the enantiomer-specific compounds ropivacaine and levobupivacaine, which provide similar efficacy to bupivacaine with a reduced risk of severe cardiotoxicity. Opioids are the other group of drugs widely used neuraxially, in particular to provide analgesia alone or more commonly in combination with other agents. The physicochemical properties of the various opioids explain the main differences in efficacy and safety between these drugs when used intrathecally, of which morphine, fentanyl and sufentanil are most commonly used. Another group of drugs including clonidine, dexmedetomidine and epinephrine (adrenaline) provide neuraxial analgesia via alpha-adrenergic receptors and are used mainly as adjuvants to local anaesthetics and opioids. Furthermore, intrathecal baclofen is in routine clinical use to treat spasticity in a number of neurological conditions. Beside these established approaches, a wide range of other drugs have been assessed for neuraxial administration to provide analgesia; however, most are in various early stages of investigation and are not used routinely. These drugs include neostigmine, ketamine, midazolam and adenosine, and the conotoxin ziconotide. The latter is possibly the most unusual compound here; it has recently gained registration for intrathecal use in specific chronic pain conditions.

[Patient-controlled epidural analgesia for labour: in practice]

OBJECTIVES

Update on patient controlled epidural analgesia for labour.

STUDY DESIGN

Literature review of the recent data on local anaesthetics, additional analgesics and of publications on the various protocols used.

DATA COLLECTION

Pubmed database was checked with the following key words: PCEA, labour, opioids, clonidine. The abstracts of the ASA meetings from 2000 to 2005 were also examined.

RESULTS

Patient controlled epidural analgesia (PCEA) is the method of choice for optimal labour pain management. The advantages of this technique are numerous. Some of them are established: consistent reduction in overall local anathetic requirement, less motor blockade, safety of the technique and team workload reduction. A better adequacy with the analgesic requirements and an increase in overall patient satisfaction are frequently retrieved, provided that the choice of the analgesics and the PCEA parameters are adequately chosen.

CONCLUSION

The use of PCEA improves the quality of analgesic management offered to the parturients who are more and more willing to have a "more natural" childbirth. The PCEA gives them more autonomy and, in fine, enables them to better enjoy this unique event. The main barrier to a more widespread diffusion of PCEA in many institutions remains the financial issue, although a well-selected device and low cost disposables allow a reduction of indirect costs by decreasing care giver workload.