A Randomized Controlled Trial Depicting Postoperative Pain Score Following Port-site Infiltration during Laparoscopy

INTRODUCTION

Diagnostic laparoscopy has been an invaluable tool for the evaluation and management of infertility for the last two decades. There are several advantages like smaller and more cosmetic incision, reduced blood loss, shorter postoperative stay, and early resumption of normal activities. But despite the minimally invasive nature of this surgery, there remain some challenges to minimize the postoperative pain following laparoscopy. Uncontrolled postoperative pain has an adverse sequel of delayed resumption of normal pulmonary function and restriction of mobility leading to increased risk of thromboembolism. There may also be an increase in the systemic vascular resistance, cardiac work, and myocardial oxygen consumption induced by the stress response.¹ So, improving postoperative pain control has become an increasingly important issue for the surgeon and anesthesiologist.²

Postoperative pain following laparoscopy is usually multifactorial. The pain that arises from port sites is somatic pain and pain that occurs due to distention of the abdominal cavity by pneumoperitoneum, and surgical handling is visceral pain. The third type of pain is the referred pain, which is felt in the shoulder tip due to gaseous distention.³ Recent advances suggest that an afferent block (with local anesthetics) achieved before nociceptive input can reduce or eliminate the onset of central neural hyperexcitability and can thus significantly reduce both intensity and duration of postoperative pain.⁴ Preemptive local anesthesia, therefore, may be more effective than postoperative analgesic administration at preventing postoperative pain. Bupivacaine is one such local anesthetic, which has a good safety profile, is long-acting and free of side effects like nausea and vomiting due to NSAIDs and fears of drug dependence as in case of opioids. It has a half-life of 2.5–3.5 hours and has been reported to provide pain control for an average of 6 hours.⁵ Present study is designed to evaluate the effect of subcutaneous administration of 0.25% bupivacaine for pain relief before diagnostic laparoscopy in infertile patients.

OBJECTIVE

To determine the efficacy of local bupivacaine injection into the incision site before diagnostic laparoscopy to reduce postoperative pain among infertile patients.

MATERIALS AND METHODS

The study population was 168 infertile women who underwent diagnostic laparoscopy at Farida Clinic and Infertility Management Center, a Dhaka-based tertiary care setup for infertility management and assisted reproduction.

Data were collected from February 2018 to November 2018. Prior approval was obtained from the ethical committee of the center.

RESULTS

Present study showed majority of patients (n = 79) belonged to age 21–30 years in both groups, which was 42 (58.3%) in group I (receiving bupivacaine) and 37 (51.4%) in group II (not receiving bupivacaine). The mean age was found to be 29.7 ± 4.5 years in group I and 30.2 ± 4.7 years in group II. The mean age was not statistically different (p > 0.05) between the two groups (Fig. 3). Majority of the patients had primary infertility in both groups, which was 47 (65.3%) in group I and 57 (79.2%) in group II. Secondary infertility was 25 (34.7%) and 15 (20.8%) in group I and group II, respectively. The difference was not statistically significant (p > 0.05) between two groups (Fig. 4). Regarding associated comorbidities, the commonest comorbidity was hypothyroidism found in both groups, 9 (12.5%) in group I and 7 (9.7%) in group II. Other comorbidities were not statistically significant (p > 0.05) between two groups (Fig. 5). Nine (12.5%) patients had the previous operation in group I and 13 (18.1%) in group II (Table 1). The mean duration of the operative procedure was comparable with 26.1 ± 5.9 minutes in group I and 26.3 ± 6.3 minutes in group II (Table 2).

When VAS score was compared between two groups in the present study, majority of patients had mild pain 1 hour after surgery—48(66.7%) in group I and 50 (69.4%) in group II (Table 3).

Three hours after surgery, the majority of patients in both groups had no pain 43 (59.7%) in group I and 40 (55.6%) in group II. Twelve hours after surgery, just before the patients were discharged from the hospital, no pain was found in 64 patients (88.9%) in group I and 6 patients 5 (90.3%) in group II. When the patients came for follow-up 7 days after surgery, no pain was observed 45 (62.5%) and 42 (58.3%) in group I and group II, respectively. So, at 1, 3, 12 hours, and 7 days after surgery, the pain score was not statistically significant (p > 0.05) between intervention and nonintervention groups.

Regarding the secondary outcomes, two patients received Inj. tramadol as additional analgesics in group I in the present study. No significant perioperative complication developed in either group during the early follow-up period.

DISCUSSION

Postoperative pain is the main factor delaying the discharge of patients undergoing day-care procedures such as laparoscopy, which adds to hospital cost. So, search for an optimum regime of pain relief in the postoperative period is going on, and many analgesics have been investigated by the surgeons and the anesthetists. Local anesthetic agents have a shorter analgesic effect, which lasts for a few hours; they have minimal sedative effects, and also have fewer side effects like nausea and vomiting commonly encountered after GA.⁶ So, they may be an ideal agent to enable the patient for early discharge from the hospital following laparoscopic surgery.

There have been numerous studies in the last few years about the use of local anesthetics as preemptive analgesia, which can be applied by using many methods, such as spinal blocks, epidural blocks, and preincisional infiltration. Several kinds of local anesthetics, such as lidocaine, bupivacaine, levobupivacaine, and ropivacaine, have been used for wound infiltration to provide postoperative pain relief.

In our study, the intervention group received 10 mL of 0.25% bupivacaine, which was injected into the 10 mm trocar entry port site before the operation and was compared with the nonintervention group who received no bupivacaine. The results showed that at 1, 3, 12 hours, and 7 days after surgery, the pain score was not statistically significant (p > 0.05) between intervention and nonintervention groups. Chundrigar et al. in 1993 in a randomized trial in England used the same dose (0.25% bupivacaine) and showed decreased postoperative pain 1–2 hours after laparoscopic surgery; however, analgesic consumption over the next 24 hours was the same in the control study.⁷ A more recent study by Agrawal in 2017 also showed that there was no significant difference in postoperative pain scores between bupivacaine and control group in the immediate postoperative period following laparoscopic cholecystectomy.⁸

This is in contrast to a similar study in Egypt in 2002 done by Shalan et al. for laparoscopic pelvic surgery, who found that pain score and the analgesic dose required were lower in bupivacaine group.⁹ Hasaniya et al. in 2001 also studied the effect of preincisional bupivacaine instillation and concluded that the mean pain scores were lower as compared to controls at 4th and 24th hour postoperatively.¹⁰

Goldstein et al. did a study on 180 patients whom he divided into three groups and compared intraperitoneal 0.5% bupivacaine, 0.75% ropivacaine, and saline instillation, for postoperative pain relief. They found that local anesthetics gave significantly good pain relief with ropivacaine being better than bupivacaine in both analgesia and opioid-sparing effect.¹¹ But ropivacaine was developed after bupivacaine was noted to be associated with increased risk of cardiac arrest, particularly in pregnant women, and is no longer generally used.¹² Levobupivacaine is an S-isomer of racemic bupivacaine that has recently been introduced as a promising long-acting local anesthetic with lower toxicity than bupivacaine.¹³

There were some studies that used bupivacaine after the surgery to assess the effect on postoperative pain. Bhardwaj et al. conducted a study of patients undergoing laparoscopic cholecystectomy. He instilled 20 mL 0.5% bupivacaine at the end of surgery in the Trendelenburg position. Postoperatively they assessed the pain score among other things, and they found that it reduced postoperative cholecystectomy pain and analgesic consumption.¹⁴

So, it has been seen that there are conflicting results in the different studies that have been done so far as there is still no consensus on the dosage, timing, and type of the local anesthetic drug to be administered.

Local anesthetics are associated with toxicity, which is dose-related. Thus, the amount of local anesthetics must be standardized not only for maximum efficacy but also to reduce drug-related toxicity. Neurological toxicity is a manifestation of the cerebral concentration of local anesthetic, and it is thus, caused by direct intravascular injection or rapid absorption. The maximally tolerated dose before manifestation of central nervous system toxicity is 12–25%, which is much higher than the usual dose that is used for local infiltration.^15,16

Besides local anesthetics infiltration and installation and reduction in troche size to <10 mm, there have been continuous efforts to improve postoperative pain management, following laparoscopic surgery by newer approach including single-incision laparoscopic surgery (SILS) and natural orifice transluminal endoscopic surgery (NOTES). These newer techniques are associated with far less postoperative pain scores and no or barely visible scar, faster recovery, and fewer wound-related complications like infection and incisional hernia and less hospital stay. But they are associated with a high cost of instruments, increased operative time, long learning curve, and insufficient data on intraoperative and postoperative complications.¹⁷ So, further works need to be done on these newer procedures, which may be the future of minimal access surgery with nonexistent postoperative pain.

LIMITATIONS OF THE STUDY

The limitation of this study is that this was conducted in a single center in Dhaka over a designated period. There should a multicenter, double-blinded randomized study with a larger sample size in the future to find out the efficacy of local bupivacaine, to reduce postoperative pain following laparoscopy. So, it is advisable to interpret the study results with caution.

CONCLUSION

To conclude, bupivacaine injection into the trocar site during diagnostic laparoscopy did not offer a significant reduction of postoperative pain in the present study. Further randomized trials are needed to evaluate the benefits of local anesthetic for postoperative pain reduction following laparoscopy.

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