Evaluation of a pumpless lung assist device in hypoxia-induced pulmonary hypertension in juvenile piglets

Abstract

Persistent pulmonary hypertension is an important cause of mortality and morbidity in term infants. The lung assist device (LAD) is a novel, pumpless, low-resistance extracorporeal oxygenator to supplement mechanical ventilation. The LAD may be associated with fewer complications compared with conventional extracorporeal membrane oxygenation. The objective was to test the feasibility and efficacy of the LAD in juvenile piglets with hypoxia-induced pulmonary hypertension. Pulmonary hypertension was acutely induced by hypoxia in six 3- to 4-wk-old acutely instrumented and intubated piglets. The LAD was attached between a carotid artery and jugular vein. Gas exchange and hemodynamic variables, including pulmonary arterial pressure (PAP) and cardiac output (CO), were measured. Successful LAD cannulation was achieved without complications in all animals. Extracorporeal shunt flow through the device averaged 18% of CO. The LAD achieved oxygen delivery of 20% of total oxygen consumption. PAP was reduced by 35% from 28 +/- 5 to 18 +/- 4 mm Hg (p < 0.05) and systemic Pao2 increased by 33% from 27 +/- 2 to 36 +/- 4 mm Hg (p < 0.05). Other hemodynamic variables remained stable. The novel LAD shows feasibility and efficacy in improving gas exchange and reducing PAPs in a juvenile animal model of hypoxia-induced pulmonary hypertension.

Figure 1

Schematic of the device design along the long axis showing blood entering centrally and flowing radially over the parallel microporous hollow fibers while the sweep gas runs inside the fibers in a counter-current fashion. (Courtesy of MC3, Ann Arbor, MI, USA).

Figure 2

Effect of the lung assist device (LAD) on pulmonary arterial pressure (PAP), pulmonary vascular resistance index (PVRI), mean systemic arterial pressure (SAP), and systemic vascular resistance index (SVRI). Hypoxia: piglet exposed to endotracheal 10% oxygen without sweep gas flow through the LAD. LAD on: piglet exposed to endotracheal 10% oxygen in combination with sweep gas running through LAD. During induced hypoxia, blood gases were drawn from the pulmonary artery. (*: p<0.05. Mean ± SEM; n=6; p<0.05 by ANOVA for PAP and PVRI; p>0.05 by ANOVA for SAP and SVRI)

Figure 3

Extracorporeal blood flow through the lung assist device (LAD) and cardiac output (CO) over time. Filled circles represent flow through the LAD. Open circles represent CO. All values are mean ± SEM.

Figure 4

Percentage of extracorporeal blood flow through the lung assist device (LAD) of cardiac output (CO) over time. All values are mean ± SEM.

Figure 5

Tracing of pulmonary arterial pressure in a representative piglet upon exposure to hypoxia (10% O₂) followed by initiation of oxygen flow through the lung assist device (LAD). Hypoxia increased pulmonary arterial pressure, which was lowered by the LAD.