Background. Reperfusion injury is a significant cause of early allogra
ft dysfunction after lung transplantation. We hypothesized that direct
pulmonary arterial infusion of an intravascular nitric oxide donor, s
odium nitroprusside (SNP), would ameliorate pulmonary reperfusion inju
ry more effectively than inhaled nitric oxide without causing profound
systemic hypotension. Methods. Using an isolated, ventilated, whole-b
lood-perfused rabbit lung model, we studied the effects of both inhale
d and intravascular nitric oxide during lung reperfusion. Group I (con
trol) lungs (New Zealand White rabbits, 3 to 3.5 kg) were harvested en
bloc, flushed with Euro-Collins solution, and then stored inflated fo
r 18 hours at 4 degrees C. Lungs were then reperfused with whole blood
and ventilated with 60% oxygen for 30 minutes. Groups II, III, and IV
received pulmonary arterial infusions of SNP at 0.2, 1.0, and 5.0 mu
g . kg(-1) . min(-1), respectively, whereas group V was ventilated wit
h 60% oxygen and nitric oxide al 80 ppm during reperfusion. Results. P
ulmonary arterial infusions of SNP even at 0.2 mu g . kg(-1) . min(-1)
(group II) showed significant improvements in pulmonary artery pressu
re (31.35 +/- 0.8 versus 40.37 +/- 3.3 mm Hg; p < 0.05) and pulmonary
vascular resistance (38,946 +/- 1,269 versus 52,727 +/- 3,421 dynes .
s/cm(-5); p < 0.05) when compared with control (group I) lungs after 3
0 minutes of reperfusion. Infusions of SNP at 1.0 mu g . kg(-1) . min(
-1) (group III) showed additional significant improvements in dynamic
airway compliance (1.98 +/- 0.10 versus 1.46 +/- 0.02 mL/mm Hg; p < 0.
05), venous-arterial oxygenation gradient (116.00 +/- 24.4 versus 34.4
3 +/- 2.5 mm Hg; p < 0.05), and wet-to-dry ratio (6.9 +/- 0.9 versus 9
.1 +/- 2.2; p < 0.05) when compared with control (group I) lungs, Lung
s that received inhaled nitric oxide at 80 ppm (group V) were signific
antly more compliant (1.82 +/- 0.13 versus 1.46 +/- 0.02 mL/mm Hg; p <
0.05) than control (group I) lungs. Conclusions. Pulmonary arterial i
nfusion of low-dose SNP during lung reperfusion significantly improves
pulmonary hemodynamics, oxygenation, compliance, and edema formation.
These effects were achieved at doses of SNP that did not cause profou
nd systemic hypotension. Direct intravascular infusion of SNP via pulm
onary arterial catheters could potentially abate reperfusion injury im
mediately after allograft implantation. (C) 1997 by The Society of Tho
racic Surgeons.