Experimental safety and efficacy evaluation of an extracorporeal pumpless artificial lung in providing respiratory support through the axillary vessels

Abstract

We sought to investigate the safety and feasibility of implanting the pumpless interventional lung assist device (Novalung; Novalung GmbH, Hechingen, Germany) to the axillary vessels either by means of direct cannulation or end-to-side graft interposition and the capability of either type of vascular access to provide respiratory support during apneic ventilation in adult pigs. Ten pigs were ventilated for 4 hours (respiratory rate, 20-25 breaths/min; tidal volume, 10-12 mL/kg; fraction of inspired oxygen, 1.0; positive end-expiratory pressure, 5 cm H2O). Thereafter, the interventional lung assist device was surgically connected to the right axillary artery and vein by using direct cannulation (n = 5) or end-to-side ringed polytetrafluoroethylene graft interposition (n = 5), and ventilatory settings were reduced to achieve near apneic ventilation (respiratory rate, 4 breaths/min; tidal volume, 1-2 mL/kg; fraction of inspired oxygen, 1.0; positive end-expiratory pressure, 20 cm H2O). Hemodynamic and intrathoracic volumes and lung cytokine levels were measured. Blood flow through the interventional lung assist device was 1.7 +/- 0.4 L/min or 30% +/- 14% of the cardiac output, and the mean pressure gradient across the interventional lung assist device was 10 +/- 2 mm Hg. The interventional lung assist device allowed an O2 transfer of 225.7 +/- 70 mL/min and a CO2 removal of 261.7 +/- 28.5 mL/min. Although the amount of blood flow perfusing the interventional lung assist device was significantly higher (P < .01) with direct cannulation (2.1 +/- 0.3 L/min) compared with that seen in graft interposition (1.3 +/- 0.3 L/min), the latter allowed similar respiratory support with reduced hemodynamic instability. The axillary vessels are a safe and attractive cannulation site for pumpless partial respiratory support. Compared with direct cannulation, graft interposition was equally able to support the interventional lung assist device-driven gas exchange requirements during apneic ventilation with better hemodynamic stability.