E. Criado et al., THE ROLE OF AIR PLETHYSMOGRAPHY IN THE DIAGNOSIS OF CHRONIC VENOUS INSUFFICIENCY, Journal of vascular surgery, 27(4), 1998, pp. 660-670
Purpose: The role of air plethysmography (APG) in the diagnosis of ven
ous disease is not well defined. We conducted this study to investigat
e the value of APG in the diagnosis of chronic venous insufficiency an
d to determine its correlation with the clinical severity of disease a
nd the anatomic distribution of reflux. Methods: We studied 186 lower
extremities with duplex scanning and venography and measured the venou
s volume, venous filling index (VFI), ejection fraction, and residual
volume fraction with APG. Limbs were categorized according to the Soci
ety for Vascular Surgery and International Society for Cardiovascular
Surgery classification of clinical severity of disease and according t
o the anatomic distribution of valvular incompetence. Results: Sixty-o
ne limbs had no evidence of disease (class 0), 60 limbs had mild disea
se (classes 1, 2, and 3), and 65 limbs had severe disease (classes 4,
5, and 6). According to the results of duplex scanning and venography,
there was no evidence of reflux in 56 limbs. Isolated superficial ven
ous reflux occurred in 52 limbs, and perforator reflux, alone or in co
njunction with superficial reflux, occurred in 30. Deep reflux, with o
r without superficial reflux, was found in 25 limbs. Deep and perforat
or reflux, with Or without superficial reflux, was found in 19 limbs.
The VFI had a sensitivity of 80% and 99% positive predictive value for
any type of reflux. The VFI was significantly different between group
s of limbs with different clinical severities of disease or different
types of reflux. The incidence of deep or perforator reflux in limbs w
ith a normal VFI value was 7%, and it was 82% in limbs with a VFI of m
ore than 5. Among 86 limbs with VFI values not corrected with use of a
thigh tourniquet, 28% did not have evidence of deep or perforator ref
lux, and among 15 limbs with VEI values corrected with the use of a to
urniquet, 33% had perforator reflux, deep reflux, or both. All APG par
ameters had low positive predictive values for severe disease or ulcer
ation. The ejection fraction and residual volume fraction did not infl
uence the clinical severity of disease, did not discriminate between t
ypes of renw, and in combination with the vm did not improve the predi
ctive value of APG. Conclusions: The VFI measured by APG is an excelle
nt predictor of venous reflux, provides an estimate of the clinical se
verity of disease, and at high levels predicts deep reflux, perforator
reflux, or both. Correction of an abnormal VFI with a thigh tournique
t is an unreliable predictor of the absence of deep or perforator inco
mpetence. The predictive value of APG for severe disease or ulceration
is poor. The ejection fraction and residual volume fraction, individu
ally or in combination with the VFI, add little to the diagnostic valu
e of APG, and their routine performance may not be clinically justifie
d.