title: Complete respiratory support with AVCO2R and CPAP-mimic ventilation for total gas exchange in sheep.
abstract: The altered respiratory mechanics in patients with chronic obstructive pulmonary disease (COPD) present unique challenges with regard to treatment during an acute exacerbation that often leads to respiratory support with mechanical ventilation. Alternative therapies are badly needed to reduce morbidity and mortality associated with mechanical ventilator use. We hypothesized that arteriovenous carbon dioxide removal (AVCO(2)R) coupled with continuous positive airway pressure (CPAP) would achieve total gas exchange eliminating the need for intubation/mechanical ventilation, thus reducing baro/volutrauma. This hypothesis was tested in six adult sedated apneic sheep with AVCO(2)R administered through a simple arteriovenous (AV) shunt for CO(2) removal. Because it is impractical to apply a CPAP mask to conscious sheep, the CPAP was mimicked in intubated/sedated sheep by positive end-expiratory pressure (PEEP) of 5-10 mmH(2)O with negligible ventilation. The AVCO(2)R and CPAP-mimic maintained Pa(o)(2) and Pa(co)(2) in the normal physiological ranges. The CO(2) removal was 120-150 ml/min through AVCO(2)R with AV blood flow of 1.1-1.5 L/min. A high fraction of inspired oxygen percentage (Fi(o)(2)) level (89 ± 3%) was required to achieve 40 ± 7% O(2) in the small bronchus. Thus, AVCO(2)R and CPAP-mimic achieved total gas exchange in anesthetized sheep and may be a potential option for acute COPD exacerbation in humans.
authors.affiliation: Department of Pediatrics, University of Kentucky College of Medicine, Lexington, USA.
authors.forename: Don
authors.initials: D
authors.lastname: Hayes
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Zwischenberger
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Zhou
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Liu
authors.forename: James E
authors.initials: JE
authors.lastname: Lynch
authors.forename: Cherry
authors.initials: C
authors.lastname: Ballard-Croft
authors.forename: Dongfang
authors.initials: D
authors.lastname: Wang
mesh_terms: D000818:Animals; D001187:Artificial Organs; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D011175:Positive-Pressure Respiration; D012756:Sheep
chemical_list: D002245:Carbon Dioxide