Table 1.
Demographic Information and Baseline Characteristics
| Variables | Total (n=356) | Placebo Group (n=178) | S-Ketamine Group (n=178) | P value |
|---|---|---|---|---|
| Age (y) | 66 ± 5.0 | 66 ± 6.0 | 66 ± 5.0 | 0.242 |
| Male | 88 (24.7%) | 46 (25.8%) | 42 (23.6%) | 0.623 |
| Female | 268 (75.3%) | 132 (74.2%) | 136 (76.4%) | |
| BMI (kg/m2) | 27 (24.0, 29.0) | 27 (25.0, 29.0) | 26 (24.0, 29.0) | 0.350 |
| ASA | 0.519 | |||
| II | 312 (87.6%) | 154 (86.5%) | 158 (88.8%) | |
| III | 44 (12.4%) | 24 (13.5%) | 20 (11.2%) | |
| Duration of illness (y) | 10 (5.0, 12.0) | 8 (5.0, 12.0) | 10 (5.0, 12.0) | 0.960 |
| Long-term analgesics usea | 136 (38.2%) | 65 (36.5%) | 71 (39.9%) | 0.513 |
| CHD | 42 (11.8%) | 24 (13.5%) | 18 (10.1%) | 0.324 |
| Hypertension | 181 (50.8%) | 95 (53.4%) | 86 (48.3%) | 0.340 |
| Arrhythmiab | 37 (10.4%) | 16 (9.0%) | 21 (11.8%) | 0.385 |
| Diabetes | 43 (12.0%) | 25 (14.0%) | 18 (10.1%) | 0.255 |
| Respiratory diseasec | 57 (16.0%) | 27 (15.2%) | 30 (16.9%) | 0.665 |
| Cerebrovascular diseased | 21 (6.0%) | 13 (7.3%) | 8 (4.5%) | 0.261 |
| Timed Up and Go test (s)e | 43 (36.0, 58.0) | 43 (35.0, 56.0) | 45 (36.0, 60.0) | 0.518 |
| AROM (°)e | 90 (80.0, 90.0) | 90 (80.0, 90.0) | 90 (80.0, 90.0) | 0.105 |
| NRS at reste | 0 (0.0, 0.0) | 0 (0.0, 0.0) | 0 (0.0, 0.0) | 0.468 |
| NRS during activitye | 4 (2.0, 4.0) | 4 (2.0, 4.0) | 4 (2.0, 4.0) | 0.423 |
| Peak NRS in PACU | 0 (0.0, 0.0) | 0 (0.0, 00) | 0 (0.0, 0.0) | 0.070 |
| Operation time (min) | 75 (65.0, 90.0) | 80 (65.0, 88.8) | 75 (68.8, 88.8) | 0.941 |
| Tourniquet duration (min) | 70 (60.0, 80.0) | 70 (60.0, 80.0) | 70 (60.0, 80.0) | 0.440 |
| Intravenous steroidf | 41 (11.5%) | 23 (12.9%) | 18 (10.1%) | 0.406 |
| Midazolam (mg) | 2 (2.0, 2.0) | 2 (2.0, 2.0) | 2 (2.0, 2.0) | >0.999 |
| Intraoperative analgesiag | 3 (0.8%) | 1 (0.6%) | 2 (1.1%) | >0.999 |
| Rescue analgesia in PACU | 0 (0%) | 0 (0%) | 0 (0%) | NE |
| S-ketamine (mg) | NE | NE | 23 (18.8, 27.5) | NE |
| Infusion volume (L) | 0.8 (0.7, 0.9) | 0.8 (0.7, 0.9) | 0.8 (0.7, 0.9) | 0.092 |
Notes: Data is shown as mean ± standard deviation, median (IQR), and number of cases (percentage). aUsing pain medication daily for at least 7 days in a row within 6 months, taking long-acting pain medication within 3 days, or using any opioid within 24 hours. bArrhythmia includes atrial premature beats, atrial bigeminy, atrial fibrillation, ventricular premature beats, and ventricular bigeminy. cRespiratory diseases include asthma and chronic obstructive pulmonary disease. dCerebrovascular disease includes previous ischemic stroke or hemorrhagic stroke. eData was collected the day before surgery. fBefore the protocol modification, some anesthesiologists administered intravenous steroids, such as dexamethasone and methylprednisolone sodium succinate, to prevent postoperative nausea and vomiting. gRescue pain relief with sufentanil or fentanyl was allowed by the anesthesiologist if spinal anesthesia was not working well enough.
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; CHD, coronary heart disease; AROM, active range of motion; NRS, numerical rating scale; PACU, post-anesthesia care unit; NE, not estimable.