Interpretation
Ghezzi et al. 19 and Grube et al. 20also failed to show effectiveness of preemptive trocar-site analgesia in
reducing postoperative pain. Arden et al. 21 reported
that intraperitoneal instillation of bupivacaine at the end of
laparoscopic hysterectomy did not reduce postoperative pain, nor did it
affect the utilization of opioid analgesics.
Nevertheless, a few studies reported beneficial effect for the
aforementioned interventions. Ravndal et al. 3reported that preemptive local anesthetics injected into the trocar
sites reduced postoperative pain at ambulation 5 hours after surgery.
Chou et al. 4showed that the combination of preoperative and postoperative
intraperitoneal Bupivacaine reduced pain at 2 and 4 hours
postoperatively.
A few systematic reviews have also addressed the role of different
interventions for reducing postoperative pain. Ong et al.22 found no beneficial effect of preemptive local
anesthetic wound infiltration on postoperative pain; however, this
intervention was shown to reduce postoperative analgesic consumption.
Marks et al 5 found that analgesia instilled
intraperitoneally significantly decreased pain during a 6-hour interval
after laparoscopy. Long et al. 10 studied the evidence
regarding the practice of preemptive analgesia in various forms. They
reported modest effect of incisional infiltrations and stated that
conclusions drawn by previous studies are conflicting. In addition, they
found that intraperitoneal analgesia given upon completion of surgery is
likely beneficial.
Our findings, namely the lack of effectiveness for both incisional site
and intraperitoneal analgesia administration, could have a number of
explanations. First, it is possible that the analgesic dosage we used is
insufficient. The maximal dosage of Bupivacaine allowed for local
analgesia in adults is 175mg, since it is associated with the highest
risk of cardiovascular toxicity among the various local anesthetics
available 23. Because we combined two modalities of
analgesia (subcutaneous and intraperitoneal), we chose the lowest dose
that had been shown to be efficient for each modality24. Therefore, it is possible that due to safety
concerns we failed to reach the threshold for adequate postoperative
pain relief. Secondly, most
patients in our study underwent minor surgeries, such as diagnostic
laparoscopies and salpingectomies. It is possible that if we included
only major surgeries (such as hysterectomies and myomectomies), higher
levels of pain would have been reported and statistically significant
differences in primary and/ or secondary outcomes would have been
obtained. Nevertheless, it is important to mention that 5mg (20ml of
0.25%) Bupivacaine instilled subcutaneously was reported to be
effective in reducing postoperative pain even in diagnostic
laparoscopies 17.
It is also possible that the
immediate postoperative pain relief, was a confounding factor since it
lowered the level of postoperative pain. However, as all the medications
administered at recovery room have an elimination half-life (T1/2) of up
to six hours, together with the fact that no difference in MME was
detected between the groups, it is safe to assume that the immediate
postoperative pain relief did not affect the primary outcome. Lastly,
our patients possibly reported only low to medium postoperative pain
because they were merely asked to move from prone to sitting position,
rather than engage in more strenuous activities, such as walking in the
ward.