Patient characteristics, CVF location, and behavior of CVF drainage investigated with 3-phase respiratory technique
| Case No. | Age (yr) | Sex | CVF Level | CVF Side | Visibility Patterna | Drainage Pattern Varies with Phaseb | Best Phase for CVF Visualization |
|---|---|---|---|---|---|---|---|
| 1 | 55 | F | T12 | R | A | N | RI |
| 2 | 49 | F | T3 | L | A | N | MI |
| 3 | 67 | M | T3 | L | A | N | V |
| 4 | 60 | F | L1 | R | A | N | RI |
| 5 | 48 | F | T9 | R | A | N | RI |
| 6 | 57 | M | T5 | L | A | Y | RI |
| 7 | 73 | M | T7 | L | C | Y | – |
| 8 | 44 | F | T7 | L | A | N | RI |
Note:—The en dash indicates that no single phase was superior; RI, resisted inspiration; MI, maximum suspended inspiration; V, Valsalva maneuver; M, male; F, female; R, right; L, left; N, no; Y, yes.
↵a The visibility pattern is classified as follows: One respiratory phase is superior to the others (A), 2 phases are equally superior to the third (B), or all respiratory phases are equivalent in depicting the CVF (C).
↵b Y indicates that the drainage pattern shifted to other portions of the epidural venous plexus with different respiratory phases; N indicates no shift.