Conventional ventilation is superior to low- or high-frequency ventilation in the Non-Beating-Heart Lung Donor (NBHLD)

Purpose: The shortage of lung transplant donors may be lessened by the use of non-heart-beating lung donors (NBHLD). Optimal minute ventilation of the NBHLD is not known. We hypothesized that a moderately high minute ventilation relative to tissue metabolism to cause alveolar-induced respiratory alkalosis will ameliorate lung tissue acidosis and improve lung parenchyma viability. Methods: After sacrifice, Sprague-Dawley rats were separated into 4 groups of 8 rats each: deflated, non-ventilated controls (group I); 2 breaths/min (group II); 10 breaths/min (group III); and 20 breaths/min (group IV). All ventilation was done with room air and volumetrically set for full chest wall expansion. Two hours after sacrifice, the lungs were excised and flushed with tryphan blue vital dye to assess cell viability. Percent non-viable type II pneumocytes/10 HPF were counted in a blinded manner by a single pathologist. Results: GROUP % non-viable cells p value I (control) 37.6 ± 5.7 (I vs. II) p = 0.195 II (2 breath/min) 25.0 ± 3.7 (II vs. III) p = 0.002 III (10 breath/min) 7.7 ± 1.5 (I vs. III) p < 0.001 IV (20 breaths/min) 42.5 ± 4.3 (II vs. IV) p < 0.05 (III vs. IV) p < 0.001 Conclusions: Ventilation of the NBHLD at a moderately high rate (10 breath/min) relative to lung metabolism gives significantly improved cell viability over low frequency or high-frequency ventilation.