Characteristics of surgery by treatment group
| Factor | Cooling vest (N=60) | No cooling vest (N=60) | ASD* |
| Duration of temperature measurements (minutes)† | 105 (83, 146) | 120 (93, 163) | 0.275 |
| Surgery started in morning (%) | 47 (78) | 44 (73) | 0.117 |
| Type of orthopaedic surgery (%)‡ | 0.294 | ||
| Hip arthroplasty | 19 (32) | 14 (23) | |
| Knee arthroplasty | 16 (27) | 15 (25) | |
| Revision of total joint | 16 (27) | 24 (40) | |
| Shoulder arthroplasty | 9 (15) | 7 (12) | |
| Preoperative factors | |||
| Surgeons’ thermal comfort | 5 (4, 5) | 5 (4, 5) | 0.050 |
| Ambient room temperature | 20.2±0.9 | 20.1±0.7 | 0.109 |
| Sound elimination headset (%) | 56 (93) | 59 (98) | 0.252 |
| Distractions or interruptions (%) | 5 (8) | 2 (3) | 0.215 |
| Surgeons’ C3B PST score | 69 (60, 76) | 69 (62, 76) | 0.080 |
| Surgeons’ C3B VMT score | 65 (57, 68) | 65 (58, 68) | 0.034 |
| Intraoperative factors | |||
| Average ambient field temperature in surgery, °C | 20.8±0.98 | 20.7±0.9 | 0.119 |
| Postoperative C3B cognitive tests | |||
| Sound elimination headset (%) | 57 (95) | 59 (98) | 0.187 |
| Distractions or interruptions (%) | 6 (10) | 5 (8) | 0.058 |
Summary statistics are presented as N (%) for categorical variables, mean±SD or median (Q1, Q3) for continuous variables.
*ASD defined as the absolute difference in mean, mean rank or proportion divided by the pooled SD. Variables with ASD>0.358 are considered to be imbalanced based on Austin (2009).16
†Surgery duration is approximated here by reporting duration of temperature measurements; actual duration was not measured.
‡Totals not equal to 100% due to rounding error.
ASD, absolute standardised difference; C3B, Cleveland Clinic Cognitive Battery; PST, processing speed test; VMT, visual memory test.