title: Hemodynamic design requirements for in-series thoracic artificial lung attachment in a model of pulmonary hypertension.
abstract: Recent thoracic artificial lung (TAL) prototypes have impedances lower than the natural lung. With these devices, proximal pulmonary artery (PA) to distal PA TAL attachment may be possible in patients without right ventricular dysfunction. This study examined the relationship between pulmonary system impedance and cardiac output (CO) to create TAL design constraints. A circuit with adjustable resistance and compliance (C) was attached in a PA-PA fashion with the pulmonary circulation of seven sheep with chronic pulmonary hypertension. The pulmonary system zeroth harmonic impedance modulus (Z(0)) was increased by 1, 2.5, and 4 mmHg/(L/min) above baseline. At each Z(0), C was set to 0, 0.34, and 2.1 ml/mmHg. The change in pulmonary system zeroth and first harmonic impedance moduli (ΔZ(0) and ΔZ(1)), the percent change in CO (%ΔCO), and the inlet and outlet anastomoses resistances were calculated for each situation. Results indicate that ΔZ(0) (p < 0.001) but not ΔZ(1) (p = 0.5) had a significant effect on %ΔCO and that %ΔCO = -7.45*ΔZ(0) (R(2) = 0.57). Inlet and outlet anastomoses resistances averaged 0.77 ± 0.16 and 0.10 ± 0.19 mmHg/(L/min), respectively, and the relationship between %ΔCO and TAL resistance, R(T), in mmHg/(L/min) was determined to be %ΔCO = -(7.45f)×(R(T) + 0.87), in which f = the fraction of CO through the TAL. Thus, newer TAL designs can limit %ΔCO to less than 10% if f < 0.75.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, USA.
authors.forename: Begum
authors.initials: B
authors.lastname: Akay
authors.forename: Julie A
authors.initials: JA
authors.lastname: Foucher
authors.forename: Daniele
authors.initials: D
authors.lastname: Camboni
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Koch
authors.forename: Ayushi
authors.initials: A
authors.lastname: Kawatra
authors.forename: Keith E
authors.initials: KE
authors.lastname: Cook
mesh_terms: D000818:Animals; D001187:Artificial Organs; D004195:Disease Models, Animal; D004867:Equipment Design; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000628:therapy*; D008168:Lung / Q000473:pathology*; D015233:Models, Statistical; D008962:Models, Theoretical; D011312:Pressure; D011474:Prosthesis Design; D011651:Pulmonary Artery / Q000473:pathology; D011652:Pulmonary Circulation; D012756:Sheep; D013909:Thorax / Q000473:pathology