Chapter 28 - Venous air plethysmography

Question 1

Techniques of venous air plethysmography

Answer 1

1) patient supine 2) inflate cuff in calf 3) elevate leg 45 degrees - zero venous volume 4) quickly stands on contralateral leg to increase venous volume 5) calf muscle pumps x 10 = ejection volume and venous filling time 6) supine and elevate leg 7) repeat abnormal study with tourniquet

Question 2

Venous filling index

Answer 2

Rate of venous filling VFI = 90% venous volume / 90% venous filling time Normal VFI < 2 Mild-moderate reflux 2-10 severe > 10

Question 3

Ejection fraction

Answer 3

Calf muscle pump function after one toe-up exercise EF = ejection volume / venous volume x 100% Normal EF > 60%

Question 4

Residual volume fraction

Answer 4

Percentage of venous volume remaining after 10 toe up movements = ambulatory venous pressure in mmHg RVF = RV/VV Normal RVF < 35%

Question 5

Air plethysmography graph

Answer 5