Literature selection
The derivation of the databases and published articles was described in Figure 1. There were 145 studies by searching database. Of them, 121 articles were excluded by screening the title and abstract. The remaining 24 studies concerning the oxycodone for visceral pain after laparoscopic surgery were identified. Among them, 14 studies were excluded due to non-randomized controlled trials (n=1), ineligible patients (n=2), ineligible comparator (n=9), and absent of eligible outcome reporting (n=2). Therefore, 10 studies [13,6,31,7,6,10,6,4,2] met our inclusion criteria.
Characteristics Of Included Studies
A total of 815 participants (including 410 oxycodone subjects and 405 controls) matched the inclusion criteria and were selected for the data analysis; study design and location, characteristics of patients (diagnose, duration of surgery, duration of anesthesia, ASA (American Society of Anesthesiologists) physical status I/II), details about interventions and measured outcomes were presented in Table 1.
Table 1
Characteristic of included studies
Study | Study design and country | Participants Age (Mean/SD, years) | Intervention and sample size(M/F/N) | Duration of surgery (mean/SD,min) | Duration of anesthesia (mean/SD,min) | ASA physical status I/II | Outcomes |
Oxycodone | Other Opioid |
Choi 2015 (7) | RCT Korea | Age 55.1/11.3; undergoing elective laparoscopic cholecystectomy | Twenty minutes before the end of surgery, the patients received 0.08 mg/kg oxycodone; 19/9/28 | Twenty minutes before the end of surgery, the patients received 1 ug/kg fentanyl; 12/14/26 | 52.3/20.0 | 67.8/17.4 | 29/25 | Postoperative pain intensity (VAS); Sedation score; Dizziness; Nausea; Vomiting |
Choi 2018(15) | RCT Korea | Age 46/11.8; elective laparoscopic cholecystectomy | Ten minutes prior to the completion of the operation, the patients received a 2 mL mixture of oxycodone (0.08 mg/kg) in isotonic saline intravenously; 14/16/30 | Ten minutes prior to the completion of the operation, the patients received a 2 mL mixture of fentanyl (1 ug/kg) in isotonic saline intravenously; 10/20/30 | 36/12.1 | 61/15 | NR | Postoperative Pain intensity (NRS) ; Nausea; Vomiting; Dizziness; Respiratory Depression |
Han 2018(16) | RCT China | Aged 50.12/10.54; elective abdominal surgery (laparotomy or endoscopy) | Oxycodone (0.1 mg/kg for endoscopy procedures; 0.15 mg/kg for laparotomy procedures) or was administrated intravenously at the end of surgery. PCIA was given to the patients immediately at the end of surgery; 55/8/63 | Sufentanil (0.1 mg/kg for endoscopy procedures; 0.15 mg/kg for laparotomy procedures) was administrated intravenously at the end of surgery. PCIA was given to the patients immediately at the end of surgery; 49/8/57 | NR | 158.2/65.85 | NR | Nausea and vomiting; Pruritus; Respiratory depression |
HWang 2014(8) | RCT Korea | Age 54.5/13.8; scheduled for laparoscopic cholecystectomy | Oxycodone (1 mg oxycodone and 1.5 mg ketorolac); NR/NR/41 | Fentanyl (10 mcg fentanyl and 1.5 mg ketorolac); NR/NR/40 | NR | NR | NR | Pain intensity (NRS); Sedation levels (Ramsey sedation scores); Nausea; Vomiting; Headache; Pruritus; Respiratory depression; Patient satisfaction |
Kim 2015(9) | RCT Korea | Age 48.1/5.3; scheduled for laparoscopic hysterectomy | Oxycodone (10 mg); NR/NR/24 | Fentanyl (100 mg fentanyl with 30-mg ketorolac); NR/NR/24 | 73.3/23.0 | NA | 46/14 | Pain intensity (NRS); Dizziness; headache; nausea; vomiting; pruritis; respiratory depression; Patient satisfaction |
Kim 2017(10) | RCT Korea | Age 46.3/5.2; Scheduled for laparoscopic supracervical hysterectomy | 52.5 mg of oxycodone, 150 mg of ketorolac, and 0.6 mg of ramosetron were mixed with saline to a total volume of 100 mL; NR/NR/64 | 700 mg of fentanyl, 150 mg of ketorolac, and 0.6 mg of ramosetron were mixed with saline to a total volume of 100 mL; NR/NR/63 | 70.8/ 22.1 | 70.8/ 22.1 | 93/34 | Pain intensity (NRS); Nausea; Vomiting; Dizziness; Drowsiness; Headache; Pruritis; Respiratory Depression; Patient satisfaction |
Koch 2008(11) | RCT Denmark | Age 43.4/11; scheduled for elective outpatient laparoscopic cholecystectomy | Patients received 10 mg oxycodone at end of surgery; 12/24/36 | Patients received 100 ug fentanyl at end of surgery; 9/28/37 | 82.4/28.5 | NA | 47/26 | Pain intensity; Sedation; Nausea; Vomiting. |
Kwon 2016(12) | RCT Korea | Age 46.2/12.8; underwent laparoscopic cholecystectomy | Patients received IV PCA with100 mg of oxycodone, 0.6 mg of ramosetron, and 86 mL of normal saline; 14/27/41 | Patients received IV PCA with 10 mg of alfentanil, 0.6 mg of ramosetron, and 76 mL of normal saline; 16/25/41 | 42.8/16.7 | NA | NA | Pain intensity (VAS); Nausea; vomiting; dizziness; headache; respiratory; pruritus; Patient satisfaction; |
Lens 2009(13) | RCT Norway | Age 46/6.9; underwent laparoscopic cholecystectomy | Patients received oxycodone 0.07 mg /kg 10–15 min before the end of surgery; After emergence, patients received PCA oxycodone 0.015 mg /kg; NR/NR/46 | Patients received morphine 0.07 mg /kg 10–15 min before the end of surgery; After emergence, patients received PCA morphine 0.015 mg /kg; NR/NR/45 | 100/29 | 123/32 | 33/58 | Pain intensity (VAS), Sedation level; Nausea; Vomiting; Itching. |
Park 2015(14) | RCT Korea | Age 46.5/8.6 undergo either elective total laparoscopic hysterectomy (TLH) or laparoscopic myomectomy | Oxycodone (a basal infusion of 0.9 mg/h, bolus dose of 0.9 mg, and lockout interval of 15 minutes); 37 females | Fentanyl (a basal infusion of 15 µg/h, bolus dose of 15 µg, and lockout interval of 15 minutes); 32 females | NA | NA | 46/23 | Pain intensity (VAS); Dizziness; headache; nausea; vomiting; Patients satisfaction |
Notes: M = number of male patients; F = number of female patients; N = number of total patients; NR = not reported; PCA = patient controlled analgesia |
Results Of Risk Of Bias Individual Studies
Risk of bias of included studies according to the Cochrane Risk of Bias tool was provided in Fig. 2. Of the included 10 studies, seven studies were rated as low risk of bias on randomization, as they used computer-generated random number sequence. Three studies[7, 6, 2] did not describe the method of randomization. Most studies stated that the allocation concealment was conducted, however four studies[7, 6, 2] did not report the information. Only half of the included studies stated that the participants and personnel were blinded. The other five studies[7, 6, 4, 2] did not report the information. For blinding of outcome assessor, one study[6] stated that partial of the outcome assessor knew the group assignment during treatment, so it was rated as high risk of bias on this domain. One study[4] did not report data for some measured outcomes including nausea, vomiting, or itching, therefore was rated as high risk of selective reporting.
Meta-analysis
Pain intensity
Nine studies[13, 6, 7, 6, 10, 6, 4, 2] measured pain intensity by VAS or NRS scale. However, only four of them[7, 10, 4] contributed data for meta-analysis. Result showed that oxycodone can significantly reduce the pain intensity than other opioids (fentanyl, alfentanil or morphine) in 30 minutes (2 RCTs, N = 218, MD -11.9, 95% CI -16.16 to -7.63), 4 hours (3 RCTs, N = 290, MD -4.73, 95% CI -8.9 to -0.57), and 24 hours post operation (2 RCTs, N = 208, MD -3.00, 95% CI -4.02 to -1.98), but not for 48 hours post operation (2 RCTs, N = 208, MD -0.62, 95% CI -3.00 to 1.76) (Fig. 3). The data of the other five studies are not available to do meta-analysis as their data were skewed. Kim 2015[6] also found a similar results as above. Choi 2018[13] and Park 2015[2] concluded that oxycodone and fentanyl have equal effectiveness in relieving postoperative pain. Choi 2015[6] found that the pain intensity in oxycodone is significantly lower than fentanyl group in half hours post operation, but this effect did not last longer than 0.5 hours. Koch 2008[6] stated that the intensity of deep abdominal pain was significantly lower in the oxycodone group at arrival, after 30, 60 and 90 min and at discharge from the PACU.
Sedation
Four studies[6, 7, 6, 4] reported this outcome. Choi 2015[6] and Koch 2008[6] used the following methods to assess sedation: “S, asleep, easily aroused; 1, awake and alert; 2, occasionally drowsy, easily aroused; 3, frequently drowsy, falls asleep during conversation; 4, somnolent, minimal or no response to stimulation”. Meta-analysis showed that no difference between oxycodone and fentanyl for sedation score at 2 (2RCTs, N = 127, RR 2.06, 95% CI 0.56 to 7.60, Fig. 4). Both studies reported that no patient had a sedation score at 3 or 4. Hwang 2014[7] also concluded that the sedation level was similar between oxycodone and fentanyl group. However, Lenz 2009[4] found a different result that sedation level was significantly less in oxycodone group compared with Morphine group (P = 0.006).
Adverse Event
All studies reported adverse events. Oxycodone may induce higher risk of dizziness (6 RCTs, N = 455, RR 2.31, 95% CI 1.64 to 3.27) and drowsiness (1 RCT, N = 127, RR 7.88, 95% CI 1.89 to 32.85). There is no difference between groups for the risk of headache, pruritus, respiratory depression, nausea, and vomiting (Fig. 5).
Patient Satisfaction
Patient satisfaction was classified into four levels: very satisfied, satisfied, neutral, dissatisfied. Meta-analysis was performed to assess the number of patients with satisfaction or very satisfaction in both groups. Result from four studies[7, 6, 10] showed that there are no significant difference between oxycodone versus other opioids for this outcome (4 RCTs, N = 350, RR 0.88, 95% CI 0.66 to 1.17, Fig. 6).