Paracorporeal Artificial Lung: Perioperative Management for Survival Study in Sheep

Abstract

An artificial lung may offer a bridge to recovery or transplant. Utilizing our recently developed paracorporeal artificial lung (PAL) in survival studies in sheep, we critically review our perioperative/anesthetic protocol. Adult Suffolk ewes (n = 15) underwent general anesthesia induced by ketamine (7-15 mg/kg, im) and isoflurane by mask, then intubated and maintained by 4.0-5.0% isoflurane titrated to mean arterial pressure (MAP) 70-110 mm Hg. After a latissimus-sparing thoracotomy and systemic heparinization (200 IU/kg), arterial grafts were anastomosed to the proximal and distal main pulmonary artery in an end-of-graft to side-of-artery fashion. A snare was passed around the pulmonary artery between anastomoses. When the snare was tightened, full pulmonary blood flow was diverted through the cannulae and immediately through the PAL. Perioperative crystalloids included a 500-mL prime, lactated Ringer's (LR) titrated to CVP 5-7 mm Hg, and a heparin infusion (activated clotting time [ACT] 250-300 s). Buprenorphine (0.3 mg im tid) controlled postoperative pain. Hemodynamic parameters, arterial blood gases (ABGs), and ACTs were measured every 6 h. Thirteen of 15 sheep survived the operation and were extubated in less than 20 min. Two groups were studied for up to 7-day survival. Both groups underwent immediate connection to the PAL diverting full pulmonary blood flow. Group 1 (n = 8) underwent immediate connection to a rigidly housed PAL, and 4 of 8 demonstrated immediate right heart failure. In Group 2 a compliance chamber was added to the PAL inflow, and 6 of 7 had stable hemodynamic function for the duration of the study. Incremental improvements in the PAL and our anesthetic and perioperative care have resulted in reliable survival in adult sheep allowing for artificial lung development.

An Ambulatory Pulmonary and Right Heart Assist Device (OxyRVAD) in an Ovine Survival Model

“…This configuration preserves native lung perfusion and metabolic function. [17][18][19] Application in a smoke-and-burn induced 100% lethal dose ARDS sheep model demonstrated successful total respiratory support for 5 days with improved survival. 20 The human main PA is too short (2.5 cm vs 6 cm in sheep) to place 2 large anastomoses for PAL graft attachment.…”

An Integrative Cardiovascular Model of the Standing and Reclining Sheep

“…Our group has considerable experience in modeling assist devices (e.g., the intraaortic balloon pump Clark et al, 1973;Philippe et al, 1980 andveno-arterial bypass pumping Clark et al, 1980;Lande et al, 1980), and we look forward to using the sheep CVS model developed herein to study a variety of emerging assist devices of different types, including the paracorporeal artificial lung (Lick et al, 2003;Zwischenberger et al, 2002).…”

Hemodynamic Effects of Pumpless Extracorporeal Membrane Oxygenation (ECMO) Support for Chronically Pressure-Overloaded Right Heart Failure in a Canine Experimental Model

“…On the other hand, maintaining the pulsatility of the blood flow through an oxygenator increases the shear stresses in comparison to the nonpulsatile flow. 24,25 A high shear stress is known to activate blood systems, 20 while systems with a very high compliance can result in low shear stresses with a resultant risk of thrombogenesis. 26 A pumpless ECMO system should thus be designed to provide minimal blood cell trauma, and such devices with low shear stresses are currently being developed.…”