Patient demographics and comparisons between bilateral ESP blocks and catheters.
| Variable | ESP Blocks (n = 12) | ESP Catheters (n = 6) | P Value |
| Age, y, mean (SD) | 66 (10) | 63 (9) | 0.539 |
| Sex, Female, n (%) | 7 (58) | 3 (50) | 0.755 |
| Race, n (%) | 0.554 | ||
| White | 12 (100) | 5 (83) | |
| Black/African American | 0 | 0 | |
| Others | 0 | 1 (16) | |
| Body mass index | |||
| Mean (SD) | 28 (6) | 29 (10) | 0.854 |
| Normal (19–25 kg/m2), n (%) | 4 (33) | 3 (50) | |
| Overweight (26–30 kg/m2), n (%) | 5 (42) | 1 (17) | |
| Obese (31–40 kg/m2), n (%) | 2 (17) | 1 (17) | |
| Morbidly obese (>40 kg/m2), n (%) | 1 (8) | 1 (17) | |
| Current smoking, n (%) | 1 (8) | 1 (17) | 0.311 |
| Comorbidities, n (%) | |||
| Anxiety | 3 (25) | 2 (33) | 0.097 |
| Depression | 0 | 2 (33) | 0.729 |
| Preoperative opioid use, n (%) | 2 (17) | 2 (33) | 0.453 |
| Preoperative opioid, mg (oral morphine equivalents), mean (SD) | 5 (14) | 16 (33) | 0.385 |
| Diagnosis, n (%) | 0.969 | ||
| Lumbar stenosis | 10 (83) | 6 (100) | |
| Scoliosis | 3 (25) | 3 (50) | |
| Spondylolisthesis | 8 (67) | 6 (100) | |
| Degenerative disc disease | 5 (42) | 5 (83) | |
| Herniated nucleus pulposis | 0 | 1 (17) | |
| Prior lumbar surgery, n (%) | 1 (8) | 1 (17) | 0.311 |
| American Society of Anesthesiologists class, n (%) | 0.443 | ||
| I | 2 (17) | 2 (33) | |
| II | 10 (83) | 3 (50) | |
| III | 0 | 1 (17) | |
| No. levels fused, n (%) | 0.198 | ||
| Total | 32 | 18 | |
| T12-L1 | 1 (3) | 0 | |
| L1-L2 | 1 (3) | 1 (6) | |
| L2-L3 | 3 (10) | 1 (6) | |
| L3-L4 | 6 (19) | 6 (33) | |
| L4-L5 | 12 (38) | 6 (33) | |
| L5-S1 | 10 (31) | 4 (22) | |
| Decompression, n (%) | 10 (83) | 6 (100) | 0.8908 |
| Fusion, n (%) | 12 (100) | 6 (100) | 0.800 |
| Duration of surgery, min, mean (SD) | 224 (73) | 174 (60) | 0.177 |
Abbreviation: ESP, erector spinae plane.