| Group Time | Control | Clonidine | Tramadol |
| Base | 0 | 0 | 0 |
| 5 minutes | 0 | 0 | 0 |
| 15 minutes | 0 | 0 | 6 |
| 30 minutes | 15 | 6 | 13 |
| 1 hour | 16 | 8 | 8 |
| 2 hours | 3 | 6 | 2 |
| 4 hours | 0 | 0 | 0 |
| 6 hours | 0 | 0 | 0 |