In six dogs and six weight-matched miniature pigs at baseline and after pulmonary embolization, pulmonary arterial compliance was determined using the pulse pressure method (C(PPM)), the three-element windkessel model (C(WK-3)), and the ratio of stroke volume to pulse pressure (SV/PP). C(PPM) was lower in pigs than in dogs at baseline (0.72 +/- 0.23 vs. 1.14 +/- 0.29 ml/mmHg, P < 0.05) and after embolism (0.37 +/- 0.14 vs. 0.54 +/- 0.16 ml/mmHg, P = 0. 07) at matched flow, but not at matched flow and pressure. C(PPM) showed the expected inverse relation with pressure and a direct relation with flow. C(WK-3) was closely correlated with C(PPM), except for all dogs at baseline where C(WK-3) was up to 100% higher than C(PPM). Excluding these data, regression analysis yielded C(WK-3) = -0.01 + 1.30. C(PPM) (r(2) = 0.97). C(WK-3) was found to be unreliable when input impedance first harmonic modulus was close to characteristic impedance, i.e., when reflections were small. SV/PP correlated well with C(PPM) (SV/PP = -0.10 + 1.76. C(PPM), r(2) = 0.89). We conclude that 1) C(PPM) is a consistent estimate of pulmonary arterial compliance in pigs and dogs, 2) C(WK-3) and SV/PP overestimate compliance, and 3) C(WK-3) is unreliable when wave reflections are small.
Nikolaos Stergiopoulos, Georgios Rovas, Sokratis Anagnostopoulos, Vasiliki Bikia, Patrick Segers
Nikolaos Stergiopoulos, Georgios Rovas, Vasiliki Bikia, Stamatia Zoi Pagoulatou, Emma Marie Roussel
Nikolaos Stergiopoulos, Stamatia Zoi Pagoulatou