Managing pain following cesarean section is challenging. Over recent years, there has been growing interest in regional nerve block techniques with promising results on efficacy, as they reduce postoperative pain and the need of supplemental analgesia, thereby lower the incidence of drug-related side effects. Aims are evaluated the efficiency of the transverse abdominis plane block in pain control in patients undergoing cesarean section. This is a prospective double-blind study which included a total of 70 adult parturients undergoing elective cesarean section. The recruited patients were randomly assigned to two equal groups: those received transverse abdominis plane block with 20 ml 0.25% bupivacaine and those received no block. Visual analogue score was used to assess pain at 2, 4, 6, 8, 12, 18 and 24 h postoperation. Time for rescue analgesia, as well as the total amount of tramadol that received by each patient, were calculated. In almost all postoperative time points, the mean pain score in transverse abdominis plane group was significantly higher than that of control group. Time to first analgesic administration was prolonged significantly in transverse abdominis plane group (8.46±4.12 hrs) as compared with control group (4.18±2.53 hrs). Mean tramadol requirement for transverse abdominis plane group was 154.8±61.13 mg and compared with 268.16±92.53 mg for control group, with a significant difference. The operative time correlated significantly with time for rescue analgesia and tramadol requirement. Transverse abdominis plane block could be an effective method in providing analgesia with a substantial reduction in pain score and tramadol requirement during the first 48 hrs after cesarean section when used as adjunctive to standard analgesia.
Analgesia; Cesarean Section; Transverse Abdominis Plane Block
The World Health Organization (WHO) suggest and that the ideal C-section rate should be less than 15% . Recently, the number of CS increasing and is now the most frequent abdominal surgery performed in the United States . Postoperative pain relief following a CS is extremely important in order to optimize maternal and neonate wellbeing . An analysis of 50523 patients from 105 hospitals questioning pain intensity on the first postoperative day revealed that CS ranked ninth for pain severity among 179 different surgical procedures .
Although not considered a major procedure, post-cesarean pain competed with orthopedic/trauma surgeries for highest pain scores. Further, ‘worst pain intensity’ and ‘pain at mobilization’ were significantly higher after CS compared with three types of hysterectomy. At least 10.9% of women experience severe pain within 24 h after CS .
Effective postoperative analgesia is critical, because women who undergo cesarean delivery rank avoidance of pain during and after surgery as their highest priority. Management of post-cesarean pain may have lasting effects, and severe acute postoperative pain is associated with persistent pain, greater opioid use, delayed functional recovery, and increased postpartum depression .
Intrathecal morphine is the gold standard single-shot drug for post-cesarean pain, providing long-lasting analgesia for 14 to 36 hours . Although most elective cesarean deliveries in the United States are performed with spinal anesthesia . Neuraxial clonidine may improve post-cesarean analgesia when used as an adjunct to local anesthetics and opioids, but it is associated with hypotension and sedation . Although more commonly used in the management of chronic pain, gabapentin has an analgesic and opioid-sparing effect in the acute postoperative period . Ketamine has analgesic and opioid-sparing effects in the first 24 hrs after non-obstetric surgery and cesarean delivery with general anesthesia . Oxycodone, hydrocodone, and tramadol are oral opioids commonly used in the cesarean delivery setting .
Wound infiltration of local anesthetics is a commonly used method of supplemental analgesia for abdominal surgery . Women who undergo cesarean delivery with general anesthesia may benefit from local anesthetics delivered via wound infiltration or TAP block. However, in patients who receive spinal anesthesia and neuraxial opioids, the benefit of single-dose local anesthetic wound infiltration is minimal. Single-dose local anesthetic wound infiltration at the time of surgery is unlikely to last beyond the duration of the neuraxial block, affect only somatic (not visceral) pain, and has variable efficacy .
Catheter-based local anesthetic instillation has been suggested as an alternative to single-dose infiltration. Continuous wound instillation of local anesthetic reduces pain scores, opioid use, and opioid-related nausea and vomiting for up to 48 hours postoperatively .
In patients who undergo general anesthesia or spinal anesthesia without intrathecal or epidural morphine, TAP blocks can significantly improve postoperative pain and reduce opioid consumption. TAP blocks have been found to provide similar analgesia after cesarean delivery compared with continuous wound site local anesthetic instillation. The duration of sensory blockade for single-shot TAP block is limited to 6 to 12 hrs, with a mean analgesic effect of 9.5 hours (8.5-11.9 hrs) . TAP blocks have been used effectively for rescue analgesia in the post-anesthesia care unit for patients with severe postoperative incisional pain who are not responding to routine analgesics and rescue opioids . The addition of sufentanil to TAP block has been shown to decrease opioid requirements after cesarean delivery, fentanyl added to TAP block did not provide additional analgesia compared with systemic administration of the same dose. These conflicting results suggest that systemic absorption may account for the improved analgesia when opioids are added to local anesthetics for transabdominis plane (TAP) block .