Preoperative DNIC testing to identify patients at risk for postoperative pain after living donor nephrectomy.

Live donor nephrectomy is performed on healthy individuals who do not receive
direct therapeutic benefit of the procedure themselves. Due to supreme minimal
invasive procedures nowadays, research is not only focussed on the fine-tuning
of these techniques, but also on the quality of life and postoperative pain. A
shift in emphasis to developing future techniques that enhance quality of life
is seen, and there is a growing need for a shift to value-conscious research
instead of fostering the *progress at any price* attitude. The donors, the
minimal invasive surgical procedures, the perioperative anesthesia and
postoperative analgesia techniques are in all procedures very comparable.
Despite the uniform approach a large variation is seen in postoperative pain.
One of the explanations could be an individually difference in diffuse noxious
inhibiting control (DNIC). Pain impulses travelling through the ascending
pathways of the somatosensory nervous system can be modulated in several ways.
A potentially strong inhibiter of impulse transfer on spinal level is the DNIC.
The functionality of DNIC seems to be a predictor for acute post surgical pain
and chronic postsurgical pain. The functionality of this pain-inhibitory system
can be easily tested in an experimental setting with quantitative sensory
testing techniques. DNIC is maximally activated by for instance an ice water
challenge. By applying a sensory stimulus, for example heath or electricity,
sensory thresholds of perception, pain and pain tolerance can be estimated
before and after activation of the DNIC. Therefore, studies on DNIC can help
us to evaluate impairments in descending pain modulation, presumably primarily
of inhibitory nature. Preoperative pain registration with questionnaires
combined with DNIC testing is a potential predictor for postoperative pain
perception. In the unique group of healthy living kidney donors it is important
to set a high standard of care and try to minimize all *side-effects* of the
operation. If the function of DNIC is disturbed this will presumably lead to
more postoperative pain. Insight in the differences in DNIC would give us the
opportunity to intervene and develop a *tailor-made* management for each
specific patient. In the Erasmus MC we use a standard protocol for analgesic
use postoperative. All patients receive a *patient controlled analgesia* device
(PCA) and paracetamol per protocol. The amount of analgesic is registered, as
well as *escape medication* for donors who have severe postoperative pain.

Whether the DNIC test can be used to make a prediction of postoperative pain
perception and consumption of analgesics after live donor nephrectomy.

Single-center, prospective observational study without invasive measurements.

The burden and risks associated with participation are limited to the
DNIC-testing, and will consume approximately two hours in total. The number of
blood samples, the number of site visits and physical examinations is the same
as in the current standard protocol for live donor nephrectomy. Participants
are asked to give a pain score using the visual analogue scale at one day
before surgery, day 0, three times a day up until the day they are discharged
and at one month after nephrectomy. Participants are asked to fill out the
EuroQol questionnaire preoperatively, at the day they are discharged and at one
month after nephrectomy. Participants are asked to fill out the SF-36
questionnaire preoperatively and at one month after nephrectomy. The risks of
this study are negligible since the DNIC-test has been validated and is already
extensively used in other studies investigating pain perception.