Epidural mepivacaine for cesarean section: effects of a pH-adjusted solution

Effect of ropivacaine, mepivacaine or the combination of ropivacaine and mepivacaine for epidural anaesthesia on the postoperative recovery in patients undergoing caesarean section: a randomized, prospective, double-blind study

BACKGROUND

Anaesthetic methods and drugs with rapid onset, rapid recovery and better postoperative analgesia are more suitable for rapid recovery in obstetric anaesthesia. We formulated the following hypothesis: a combination of mepivacaine and ropivacaine could provide a longer analgesic effect and have more advantages in terms of rapid-recovery indicators.

METHODS

A total of 180 pregnant women scheduled to undergo elective caesarean sections were randomly assigned to three surgical groups, which received 2% mepivacaine (Group M), 2% mepivacaine + 0.75% ropivacaine (Group MR) (Volume 1:1) or 0.75% ropivacaine (Group R) through an epidural catheter. The situation of postoperative analgesia and other indicators of rapid recovery were recorded.

RESULTS

One hundred and fifty patients were included in the final analysis. Their demographic data were similar. The visual analogue scale (VAS) scores of Group MR and Group R were lower than Group M at 1 and 2 h after surgery both at rest and with movement (P < 0.05), and the time to first ambulation in Group MR (17.38 ± 2.06 h) and Group M (17.20 ± 2.09 h) was shorter than that in Group R (22.18 ± 1.74 h) (P < 0.05).

CONCLUSION

Application of 2% mepivacaine combined with 0.75% ropivacaine for epidural anaesthesia can provide longer postoperative analgesia and earlier ambulation, these effect may be more suitable than that of 2% mepivacaine or 0.75% ropivacaine alone for caesarean section.

TRIAL REGISTRATION

This study was registered at Chinese Clinical Trial Registry (Registration number: ChiCTR 2300078288; date of registration: 04/12/2023).

Anesthetic Considerations for Cesarean Delivery After Uterine Transplant

Infertility has many etiologies and can have devastating consequences for young couples attempting to bring children into the world. Uterine factor for infertility is related to either uterine agenesis (Mayer-Rokitansky-Küster-Hauser [MRKH] syndrome), unexpected hysterectomy, or presence of a nonfunctioning uterus. In this review, a patient with MRKH syndrome underwent donor uterus transplantation at the Cleveland Clinic, conceived, and delivered the first healthy baby in the United States and the second worldwide. Additionally, we review the pertinent literature on anesthesia problems. Donor-related uterine transplant is a recent medical innovation requiring multidisciplinary expertise. In patients who deliver successfully, according to the current literature, the transplanted uterus can be used for one more pregnancy only if the mother so desires, otherwise cesarean hysterectomy (C-Hyst) should be performed. In the observed case, C-Hyst was performed because the patient developed placenta accreta and the couple desired no further pregnancy. In summary, with our limited data, careful management of these patients is required to ensure the best outcome for the mother and the newborn fetus.

Effect of alkalinization on the local analgesic efficacy of ketamine in the abaxial sesamoid nerve block in horses

The objective of this study was to determine the effects of the alkalinization on the local analgesic efficacy of 1% ketamine in the abaxial sesamoid nerve block in horses. Thirty-six mature healthy horses were randomly assigned to four groups for the following treatments; an abaxial sesamoid block with 5 mL of saline solution (control saline); an abaxial sesamoid block with 5 mL of a solution containing 1% ketamine (KETs 1%); an abaxial sesamoid block with 5 mL of a solution containing saline solution and 0.5 mEq of sodium bicarbonate (control bicarbonate); and an abaxial sesamoid block with 5 mL of a solution containing 1% ketamine and 0.5 mEq of sodium bicarbonate (KETb 1%). All blocks were performed in one randomly selected front leg. To determine analgesia, hoof withdrawal from thermal stimulus from radiant heat lamp was assessed. Before each block, the hoof withdrawal reflex latency (HWRL) (time between lamp illumination and withdrawal of the hoof) was determined; after the block, local analgesic effects were determined using the heat lamp at 2 and 5 min after the injection and then every 5 min for 1 h. In KETs 1% group, there were significant increases in HWRL between basal values and values from 2 to 10 min after an abaxial sesamoid block. In KETb 1% group, significant increases in HWRL was collected between the basal value and values from 2 to 25 min following an abaxial sesamoid block. In KETs 1% group, of the nine horses, four had an abaxial sesamoid block that was unsuccessful. However, in KETb 1% group, only one of the nine horses had an abaxial sesamoid nerve block that was unsuccessful. The alkalinization of a 1% ketamine solution produced a more consistent and persistent local analgesia in horses when compared with 1% ketamine solution alone.

[Alkalinization of local anesthetics: theoretically justified but clinically useless]

PURPOSE

In vitro studies have demonstrated the potential advantages of alkalinization on anaesthetic activity, by decreasing the ratio of ionized to nonionized molecules, there by permitting more rapid penetration of local anaesthetic through biological membranes, thus decreasing the onset time. The proportion of each form depends on the pKa of the agent and the ultimate pH of the solution. When NaHCO3 is mixed with local anaesthetics, CO2 is produced. Carbon dioxide has been reported to enhance local anaesthetic action by diffusion trapping of the cationic form in pH gradient combined with a direct depressant action of CO2. The purpose of this study was to examine if clinical studies confirmed the in vitro action of alkalinisation.

SOURCE

The literature pertinent to alkalinization of local anaesthetics published in the major anaesthesia and pharmacology journals of North America and Europe.

PRINCIPAL FINDINGS

While in vitro studies have demonstrated potential advantages for alkalinization on anaesthetic activity, clinical studies have shown that alkalinization of local anaesthetics produces inconsistent results. For bupivacaine and etidocaine, alkalinization of local anaesthetic solution can produce precipitation, thus limiting the feasibility of increasing the pH.

CONCLUSIONS

On the basis of this review, routine alkalinization of local anaesthetics is not recommended.

Alkalinization improves the quality of lidocaine-fentanyl epidural anaesthesia for caesarean section

This double-blind randomized study of 116 healthy women was undertaken to evaluate whether alkalinization potentiated the analgesic effects of epidural fentanyl-lidocaine for elective Caesarean section. After a test-dose of 3 ml, lidocaine 2% with adrenaline 1:200,000, all patients received 100 micrograms, fentanyl in 5 ml saline and they were then divided into two groups, to receive incremental doses of 5 ml lidocaine 2% with adrenaline 1:200,000 with or without 0.1 mEq.ml-1 sodium bicarbonate, to obtain anaesthesia to T4. The addition of bicarbonate to lidocaine resulted in a mean (SD) pH increase from 6.58 (0.01) to 7.14 (0.02) and in a mean PCO2 increase from 3.8 (0.8) to 345.1 (5.9) mmHg. Onset of sensory analgesia to the S1 segment as well as the interval between the block and the delivery of the baby were shorter in the bicarbonate group (respectively 15.4 (6.9) vs 18.9 (4.8) min and 28.9 (9.5) versus 33.9 (11.8) min; P < 0.01 and 0.05). No differences were noted in the onset to T4 or in the degree of motor block. The percentage of patients experiencing pain during surgery and requiring intravenous analgesics was higher in the group which did not receive bicarbonate (3% vs 16%; P < 0.05). There were no differences in intraoperative maternal side-effects, neonatal outcome or in maternal venous and umbilical venous and arterial lidocaine concentrations between the groups. The concentrations of fentanyl in maternal plasma, umbilical artery, and the umbilical artery to maternal vein ratio were greater in the alkalinized group (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)