◊ BACKGROUND:
The administration of low-dose bupivacaine can limit the distribution of spinal block to reduce adverse haemodynamic effects. Intrathecal opioids can enhance analgesia in combination with subtherapeutic doses of local anaesthetics. We aimed at comparing the efficacy of intrathecal fentanyl and sufentanil with low-dose diluted bupivacaine for transurethral prostatectomy (TURP) in elderly patients.
◊ METHODS:
Seventy patients undergoing TURP were randomly allocated into two groups. Group F (n=35) received fentanyl 25 µg+bupivacaine 0.5% (0.8 ml)+normal saline 0.3 ml and Group S (n=35) received sufentanil 5 µg+bupivacaine 0.5% (0.8 ml)+normal saline 0.7 ml—in total, bupivacaine 0.25% (1.6 ml) intrathecally. Onset and duration of the sensory block, the degree of the motor block, side-effects, and the perioperative analgesic requirements were assessed.
◊ RESULTS:
The median peak level of the sensory block was significantly higher in Group S than in Group F (P=0.049). Group S required fewer perioperative analgesics than Group F (P=0.008). The time to the first analgesic request was longer in Group S (P=0.025). There were no differences between the groups for the onset and recovery time of the sensory block, degree of the motor block, quality of anaesthesia, or adverse effects.
◊ CONCLUSIONS:
Low-dose diluted bupivacaine with fentanyl 25 µg or sufentanil 5 µg can provide adequate anaesthesia without haemodynamic instability for TURP in elderly patients. However, sufentanil was superior to fentanyl in the quality of the spinal block produced.
◊ Reviewed by M. Pitkänen, MD. PhD.
Chief Anaesthesiologist
Orton - Invalid Foundation - Orthopedic Hospital, Helsinki, Finland
In this study, the opioids sufentanil and fentanyl were used in order to intensify spinal anaesthesia with a small dose of bupivacaine. Spinal anaesthesia is commonly used for transurethral resection of the prostate. Usually, these patients are elderly with several concomitant diseases. Therefore, a small dose of local intrathecal local anaesthetic is practical to limit the spread of anaesthesia and thus to avoid hypotension.
In the present study this was successfully accomplished. No hypotension occurred in patients aged 58-85 years. Anaesthesia was good or excellent in 68 out of 70 patients and only two patients needed supplementary analgesics intraoperatively.
The authors used 4 mg of bupivacaine as a hyperbaric solution, and mixed it with either 25 µg fentanyl or 5 µg sufentanil. They added saline to reach the final volume of 1.6 ml.
Both groups mainly differed in peak sensory block level, need for postoperative analgesics, and time to first analgesic request with sufentanil resulting in higher block, less need for postoperative analgesics after a longer period of time. The authors speculate that these differences were due to the higher density of the used sufentanil solution.
I do not agree with the proposed mechanism. The density of the used hyperbaric bupivacaine can be approximated at 1.023 g/ml at 37 °C (depending on the source). It was diluted with saline and sufentanil or fentanyl with densities of about 0.999 g/ml. This should have led to densities of about 1.013 and 1.012 g/ml of the sufentanil and fentanyl solution, respectively. Thus, there is only a slight difference. Authors claim this to be significant as a very small difference in densities markedly affected the spread of the solutions in a spinal canal model [1]. However, in Stienstra's model the solutions were either hypobaric or hyperbaric, and therefore even small differences certainly had an effect. Both of the solutions in the present study were clearly hyperbaric (>1.001 g/ml) for which the small differences cannot be remarkable. In addition, the patients were sitting for five minutes. One could expect that the denser sufentanil solution would have less spread after the period of sitting which is contrary to the results of the study. The difference between the peak levels is marginal (T11-L1; p < 0.049). The fact that there was no difference in intraoperative pain also supports the view that the solutions produced an equal block.
Most important and interesting was the difference in the duration of analgesia. Usually, larger spread of spinal block causes faster elimination and shorter duration of the block. However, here, the solution with a larger spread caused longer analgesia.
According to previous studies, the used doses of fentanyl and sufentanil were equipotent. In this study of elderly men after TURP operation, the pain relief of intrathecal sufentanil clearly lasted longer and was more effective than that of fentanyl. There are some studies with similar results, but the difference has not been as clear as in this study [2].
In my own experience, especially in ambulatory surgery, intrathecal fentanyl has caused an annoying frequency of pruritus. Surprisingly, in the present study, there were no patients complaining about pruritus in either group.
To conclude, according to this study, TURP can be safely performed with intrathecal anaesthesia through 4 mg of hyperbaric bupivacaine combined with either 25 µg fentanyl or 5 µg sufentanil. Of those sufentanil provides longer and more effective postoperative analgesia.
◊ References:
[1] Stienstra R, Gielen M, Kroon JW, Van Poorten F.
The influence of temperature and speed of injection on the distribution of a solution containing bupivacaine and methylene blue in a spinal canal model.
Reg Anesth. 1990 Jan-Feb;15(1):6-11.
[2] Nelson KE , Rauch T, Terebuh V, D'Angelo R.
A comparison of intrathecal fentanyl and sufentanil for labor analgesia.
Anesthesiology. 2002 May;96(5):1070-3.
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