Various postoperative analgesic methods are widely used in clinical practice. In recent years, our hospital has used small doses of ketamine compounded with fentanyl and bupivacaine for post-epidural analgesia. The analgesic effect is good, with fewer complications than post-epidural analgesia with fentanyl compound alone, which can reduce nausea and vomiting, skin pruritus, urinary retention, blood pressure drop and other adverse effects.
METHODS: One hundred and twenty patients, aged 18-70 years, undergoing elective abdominal surgery under epidural anesthesia in the last six months were selected, including 20 cases of upper abdominal surgery with epidural puncture points T9-10 and T10-11, and 100 cases of lower abdominal surgery with epidural puncture points T12-L1, L1-2 and L2-3. 47 cases were male and 73 cases were female. Analgesic pump (volume 100ml. 2ml/h constant speed)
Group A: fentanyl alone 0.8mg + 0.375% bupivacaine 20ml + saline after = 100ml
Group B: fentanyl 0.2mg + ketamine 100mg + 0.375% bupivacaine 20ml + after saline = 100ml
Patients were randomly divided into two groups, 60 cases in each group. There was no statistical difference in age, weight, height, type of surgery, and duration of surgery between the two groups, and the patients’ vital signs were stable and the anesthetic effect was satisfactory during the operation. 30 minutes before the end of the operation, the epidural catheter was connected to an analgesic pump, and the analgesic solution was injected at a constant rate of 2ml/h continuously, respectively. At 4h, 8h, 12h, 24h and 48h postoperatively, HR, BP, RR and SPO2 were all normal, and the excellent rate of visual analgesic score (VAS) analgesic effect was 98.3% in group B and 81.6% in group A. The difference between the two groups was statistically significant (P < 0.01). the survival rate of adverse reactions such as nausea and vomiting, skin itching and urinary retention in group B was lower than that in group A.
See Table 1 Comparison of analgesic effect and adverse reactions between the two groups
Analgesic effect
Adverse reactions
Group
Number of cases
Excellent
Good
Poor
Excellent rate %
Nausea
Vomiting
Itching
Urinary retention
Group A
60
37
12
11
81.60
10
4
4
3
Group B
60
55
4
1
98.30
4
1
0
0
The results of this group showed that the analgesic effect of fentanyl compounded with ketamine was more satisfactory in group B compared with group A, and the incidence of adverse reactions was bottom.
Discussion: Ketamine is a potent narcotic analgesic with high lipid solubility, rapidly diffuses into the subarachnoid space to reach the spinal cord, selectively acts on the spinal conduction system, and directly acts on opioid receptors to produce analgesic effects. Ketamine is a non-competitive antagonist of NMDA receptors. Intrathecal administration blocks the activation of NMDA receptors by excitatory amino acids, inhibits Ca ion channel opening, reduces Ca ion inward flow and inhibits the CAMP-PKA-CREB signaling pathway, and small doses of ketamine can enhance the analgesic effect of opioids. Fentanyl is a commonly used postoperative analgesic drug that modulates pain through opioid receptors. The excitatory effect of fentanyl on the central chemoreceptors of medullary vomiting is proportional to the drug concentration of epidural analgesic solution fentanyl, and low concentration of fentanyl can reduce vomiting and other adverse effects in patients. fentanyl compounded with small doses of ketamine reduces the dosage of fentanyl and reduces the adverse effects of opioids, but the analgesic effect is better.