Numbing the nerves of the chest with injections beside the spine did not lead to clearly less lasting pain after open chest surgery than an epidural, a randomised trial in the UK has found. Six months on, the difference between the two methods may be due to chance. The trial, published in The BMJ, was open label: participants and staff knew which method was used.
In an operation called a thoracotomy, surgeons open the chest through a cut between the ribs. The researchers wanted to know whether one of two ways of numbing the chest around the operation leaves fewer people with pain after surgery that lasts for months.
770 adults at 15 centres
In all, 770 adults due to have a thoracotomy at 15 chest surgery centres in the UK took part between 2019 and 2023. Their average age was 66.6 years, and 428 (56%) were men. Chance decided which method each of them received. In one group, a local anaesthetic, a drug that numbs the area, was injected three times beside the spine before the first cut, and a thin tube was then left there to keep giving it. This is called a paravertebral block. In the other group, a thin tube was placed through the back into the space around the spinal cord, and the anaesthetic was given through it before the first cut: a thoracic epidural.
Of those who joined, 33 did not have the operation in the end, so 737 people were analysed: 364 in the block group and 373 in the epidural group. The trial was designed to measure how many had chronic pain six months after joining, meaning chest pain that was at least moderate at its worst over the past week.
No clear difference at six months, but different side effects
After six months, 59 of the 272 people assessed in the block group (22%) had chronic pain, against 47 of the 292 assessed in the epidural group (16%). This difference may be due to chance, so the trial found no clear difference between the two methods.
On the day after the operation, both the worst and the average pain were somewhat greater with the block. On the second and third day there was no difference.
The side effects differed. A fall in blood pressure was less common with the block than with the epidural (12% against 18%), and so was itching (4% against 12%). Difficulty passing urine, however, was more common with the block (12% against 6%). Other complications were similar in both groups.
Researchers back the use of both methods
The researchers conclude that the paravertebral block did not reduce chronic pain at six months compared with the epidural. The epidural gave slightly better pain relief on the day after the operation, but no difference after that, and complications were comparable. In their view, the findings support the continued use of both methods.
