Table 1.
Characteristics of the 33 trials included in the meta-analysis.
| Publication year, median (range). | 2015 (1994–2021) |
| Single-center trials, n (%) | 32 (96) |
| Trial size, median (range) | 60 (27–316) |
| Continent of origin | |
| Europe, n (%) | 9 (27) |
| Asia, n (%) | 15 (45) |
| North America, n (%) | 3 (9) |
| South America, n (%) | 2 (6) |
| Africa, n (%) | 4 (12) |
| Type of surgery | |
| Abdominal, n (%) | 9 (27) |
| Uro-gynecological, n (%) | 13 (39) |
| Orthopedic, n (%) | 1 (3) |
| Neurological, n (%) | 3 (9) |
| ENT, n (%) | 4 (12) |
| Thoracic, n (%) | 2 (6) |
| Mixed, n (%) | 1 (3) |
| Anesthesia maintenance | |
| Propofol, n (%) | 9 (27%) |
| Halogenated agent, n (%) | 25 (76%) |
| OFA group | |
| Active drug, n (%) | 24 (72) |
| Dexmedetomidine and Lidocaine combined |
22 (66) 4 |
| Ketamine, n (%) | 2 |
| Magnesium, n (%) | 1 |
| Combination, n (%) | 3 * |
| Clonidine, n (%) | 1 |
| Saline, n (%) | 7 (21) |
* Association between ketamine, lidocaine, and magnesium for one trial and dexmedetomidine, ketamine, and lidocaine for two trials.