Diagnostic laparoscopy is a common outpatient procedure in an infertility clinic. Post-laparoscopic shoulder tip pain is one of the most frequent complications after this procedure. It has been reported in 35-63% of all cases . It is presumed to be secondary to peritoneal stretching and diaphragmatic irritation by CO2 gas. Shoulder tip pain could contribute to patients' morbidity by increasing their analgesic requirements and it may delay the return to normal daily activities .
Positioning, abdominal massage, passive drainage and suprahepatic suction of residual gas have all been attempted to decrease shoulder tip pain; these efforts have met with variable success [2,3]. The benefits of intraperitoneal irrigation or infiltration with local anaesthetics have been demonstrated following day case gynaecological procedures [4,5]. However, this analgesic intervention cannot be applied to patients undergoing diagnostic laparoscopy using a short Veress needle with only one small suprapubic puncture site. We observed that both suprascapular nerve block and non-steroidal anti-inflammatory drugs (NSAIDs) were effective in patients suffering from severe shoulder tip pain after operation. It was thought that prophylactic peripheral nerve block or percutaneous NSAIDs might reduce the incidence and severity of shoulder tip pain after laparoscopy. This prospective randomized study was conducted to evaluate the efficacy of performing a prophylactic suprascapular nerve block with bupivacaine 0.5% compared with piroxicam patches on the relief of shoulder tip pain after laparoscopy.
The study was approved by our hospital's Ethics Review Board and informed consent was obtained from all patients. Sixty female outpatients (ASA I) undergoing diagnostic laparoscopy in the infertility clinic were randomly assigned to one of three groups. Preoperative exclusion criteria were refusal of consent, the inability to understand, and a history of previous laparoscopy. Intraoperative exclusion criteria were the performance of an additional procedure or surgery.
Patients in the control group (n = 20) did not receive any prophylactic treatment. Patients in the suprascapular nerve block group (n = 20) received a suprascapular nerve block with bupivacaine 0.5% 5 mL to both shoulders before the induction of anaesthesia whilst in the preparation area. The block was performed at the suprascapular notch with the patient in the sitting position using the posterior approach described by Moore . The skin was infiltrated with lidocaine 1% 1 mL. Under sterile conditions, a 25-G needle, 2.5 cm long, was introduced perpendicularly to the skin. There was loss of resistance when the needle slid into the suprascapular notch. The patients then complained of paraesthesia. Bupivacaine 0.5% 5 mL with 1:200 000 epinephrine was then injected while the investigator observed the patient for any signs of systemic toxicity. Patients in the piroxicam patch group (n = 20) had one 48 mg piroxicam patch (Trast patch®; SK Pharma Co., Seoul, Korea) applied to the skin over each shoulder before the induction of anaesthesia.
All patients received total intravenous anaesthesia with fentanyl 1 μg kg−1, vecuronium 0.05-0.1 mg kg−1 and a target concentration of propofol 4-8 μg mL−1 using a Master® TCI syringe pump (Becton-Dickinson infusion system, Le Grande Chemin, France). The airway was secured by a laryngeal mask airway and controlled ventilation of the lungs was maintained with 100% oxygen. Monitoring consisted of an automated blood pressure cuff, an electrocardiogram, a capnogram and pulse oximetry. A pneumoperitoneum was established using CO2 by insertion of a Veress needle, and insufflation was commenced at 1 L min−1 for the first 1000 mL and thereafter at 6 L min−1. Diagnostic laparoscopy was then performed at an insufflation pressure of 12 mmHg. Before removal of the instruments, residual CO2 was released before the incision was closed.
After emergence from anaesthesia, the patients were transferred to the recovery room and were discharged when the usual discharge criteria were met. In the recovery room, postoperative analgesics were given when requested by the patients. The analgesics consisted of nalbuphine 10 mg or ketorolac 30 mg, intramuscularly. Shoulder tip pain and wound pain were recorded on a visual analogue pain scale (VAS). Pain and any other adverse effects were observed at 1, 3, 6, 12 and 24 h after surgery in the recovery room and by subsequent telephone call.
Differences in patient characteristics data, and operative and anaesthetic variables were compared with the use of ANOVA. Dichotomous data, e.g. the need for postoperative analgesics, were evaluated by a χ2-test. The Kruskal-Wallis test with Bonferroni correction was performed for differences in the VAS between groups. P < 0.05 was taken as being statistically significant.
There were no significant differences in patient characteristics, operative or anaesthetic data between the three groups (Table 1). Sixteen patients (80%) in the control group, 15 (75%) in the suprascapular nerve block group and nine (45%) in the piroxicam patch group complained of shoulder tip pain during the observation period (P < 0.05). With the piroxicam patch, shoulder tip pain scores on movement were significantly lower compared with the controls at 3, 6 and 12 h after surgery, and were significantly lower compared with the suprascapular nerve block method at 6 and 12 h (Fig. 1a). With the piroxicam patch, the shoulder tip pain scores during rest were significantly lower compared with the controls at 3 and 6 h, and were significantly lower compared with suprascapular nerve block at 6 h (Fig. 1b). There was no statistically significant difference between the suprascapular nerve block group and the control group pain intensity at rest and on movement.
Four patients in the control group, three in the suprascapular nerve block group and none in the piroxicam patch group requested analgesics for shoulder tip pain before discharge.
The intensity of wound pain at rest and on movement was not statistically different between the three groups (Fig. 2). In the recovery room, four patients in the control group, two in the suprascapular nerve block group and two in the piroxicam patch group asked for rescue analgesia for lower abdominal pain. Apart from postoperative pain, there were no relevant complications in either group (Table 2). None of the patients in the suprascapular nerve block group had symptoms of bupivacaine toxicity.
This study presents a higher percentage of patients experiencing shoulder tip pain than has been reported previously. The incidence rate of shoulder tip pain in the control group was 80%, in the suprascapular nerve block group was 75% and in the piroxicam patch group was 45%. The incidence rate with the piroxicam patch was significantly lower compared with the two other groups. The high incidence rate of shoulder tip pain in this study may have been because all the patients were encouraged to ambulate as early as possible.
The suprascapular nerve provides sensory fibres to a large area of the shoulder, including the superior and posterosuperior regions of the shoulder joint, capsule and the overlying skin. Although a suprascapular nerve block gives excellent pain relief in various shoulder pain disorders [7-10], no data were available on the efficacy of this nerve block for shoulder tip pain after laparoscopy. In the present study, prophylactic suprascapular nerve block did not reduce either the incidence rate or the intensity of shoulder tip pain.
Jackson and colleagues  demonstrated that residual gas can be a prominent cause of pain after laparoscopy, and the degree of pain experienced may relate to the surface area of the irritated diaphragm. Perry and Tombrello  suggested that the aetiology of postural shoulder pain after laparoscopy was the loss of the suction effect on the dome of the liver, with subsequent painful traction of the triangular and coronary ligament when sitting or standing. Riedel and Semm  showed that the amount of subdiaphragmatic pain correlated positively with the amount of insufflation of the gas. They suggested that the gas irritated the phrenic nerve and that a possible mechanism was a decreased pH as a result of the acidic CO2. Moreover, the temperature of the gas used for insufflation during laparoscopy, the duration of pneumoperitoneum and the pressure of the CO2 gas may also have an impact on shoulder tip pain after laparoscopy . This may explain why the peripheral nerve block had no effect on this pain.
The present study identified a significant reduction in shoulder tip pain as a result of the application of piroxicam patches to these patients recovering from laparoscopy. The technique was easy to perform and did not delay surgery. However, the lack of any therapeutic effect of the piroxicam patches on wound pain suggests that percutaneous piroxicam may not be sufficient to control the incisional somatic pain. As our nursing personnel, who were responsible for pain assessment, were not blinded to the piroxicam patches, observer bias cannot be excluded. Future studies with across-route comparisons should use a double-dummy design to ensure proper blinding.
Piroxicam compared with the other NSAIDs shows weak in vitro transdermal penetration at about 0% ionization (Kp = 0.002 cm h−1), a small flux (CJ = 0.08 μg h cm2) and a long lag time (T1 = 13 h), and it has been suggested that considering the whole permeation profile, ketorolac may be the most suitable NSAID for a transdermal system . More research on the relief of shoulder tip pain with different transdermal NSAID systems may be indicated.
Expectation of pain reduction following prophylactic treatment could directly cause subsequent pain relief. Placebo analgesia may occur when subjects ask for pain relief. According to the response expectancy theory, anticipating pain relief appears to play a mediating role in producing placebo analgesia . However, in our study there was a discrepancy between the results with the prophylactic suprascapular nerve block and the prophylactic piroxicam patch. In addition, any patients with prior experience of shoulder tip pain after laparoscopy were excluded from the study. Moreover, the apparent benefit of suprascapular nerve block in a pilot study could be attributed to a 'placebo-anticipated' analgesic effect.
It is concluded that the prophylactic piroxicam patch is a safe and non-invasive analgesic technique to reduce the incidence rate and severity of shoulder tip pain after diagnostic laparoscopy. A prophylactic bilateral suprascapular nerve block does not seem to be effacious in this setting.
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