The influence of supplementary regional infiltration anesthesia with ropivacaine on postoperative pain, nausea and vomiting in patients undergoing mamma surgery under general anesthesia

The incidence of postoperative nausea and vomiting (PONV) varies from 20 to 80%
in patients undergoing mamma surgery. PONV are strongly related to
postoperative pain.
PONV are also well known side effects of opioids. Appropriate pain management
during and after surgery without, or with a lower dose of opioids, may decrease
the incidence of PONV. Earlier studies with different surgical operations
showed that combining general anesthesia with regional infiltration anesthesia
with a long acting local anesthetic provided superior and prolonged analgesia,
compared with general anesthesia alone.
Therefore, regional infiltration anesthesia of the mamma with a long acting
local anesthetic could provide better analgesia in mamma surgery under general
anesthesia compared to the same surgery under general anesthesia alone. This
may lead to decreased incidence of PONV and decreased postoperative use of
opiates and anti-emetics. Ropivacaine is chosen as a long acting local
anesthetic because of its superior toxicological profile compared to
bupivacaine.

To investigate that in mamma surgery, regional infiltration with ropivacaine
0,75% added to general anaesthesia causes less postoperative pain, nausea and
vomiting compared to general anaesthesia alone.

doubleblind placebo controlled randomized intervention study

Regional infiltration anesthesia of the ipsilateral breast with ropivacaine
0,75% (maximum volume 0,47 ml/kg) or placebo (a comparable volume of NaCl 0,9%).
The regional infiltration consists of deep subcutaneous infiltration parallel
to the clavicle, in the ipsilateral parasternal line and in a line parallel to
and 0-1 cm posterior of the ipsilateral anterior axillary line. The
infiltration trajects are from medial to lateral alongside the clavicle and
from caudal to cranial at the trunk.

The burden associated with participating consists of three subcutaneous
injections with a total maximum volume of 0,47 ml/kg (with a maximum dose of
300 mg) of ropivacaine 0,75% or the same amount of NaCl 0,9%. Injections will
be given under general anesthesia (which is already part of operating
procedure).
Participation in this study includes side effects of infiltration anesthesia:
inadvertent intravascular injection, bleeding in the infiltration traject and
ipsilateral pneumothorax or numbness in the ipsilateral arm, due to brachial
plexus involvement. Side effects of ropivacaine are mainly caused by systemic
administration and include convulsions, hypotension and nausea. Hypotension and
nausea are frequently seen with operating procedures and it is impossible to
distinguish them as side effects due to the clinical situation from side
effects caused by the drug or field block.
The risk of these side effects can be minimized by careful injection and
therefore thorough training of the anesthesiologists participating in the study
will be performed .