Inhaled but not intravenous milrinone prevents pulmonary endothelial dysfunction after cardiopulmonary bypass.
OBJECTIVE
Cardiopulmonary bypass triggers a systemic inflammatory response that alters pulmonary endothelial function, which can contribute to pulmonary hypertension. Milrinone is a type III phosphodiesterase inhibitor. The objective of this study was to compare the effects of inhaled and intravenous milrinone on the pulmonary endothelium-dependent relaxations and hemodynamic and oxygenation parameters after cardiopulmonary bypass in a porcine model.


METHODS
Five groups of Landrace swine were compared: (1) control group, no cardiopulmonary bypass; (2) bypass group, 90 minutes of normothermic bypass and 60 minutes of reperfusion; (3) inhaled milrinone group, bypass preceded by a 1.8-mg bolus of inhaled milrinone followed by a continuous milrinone nebulization; (4) intravenous milrinone group, bypass preceded by 2 mg of intravenous milrinone; and (5) inhaled NaCl group, bypass preceded by inhaled saline solution. After sacrifice, pulmonary arterial endothelium-dependent relaxations to acetylcholine and bradykinin were studied in organ chambers.


RESULTS
Inhaled milrinone caused less hypotension ( P < .05), a lesser decrease in peripheral vascular resistances ( P < .01), and a lower heart rate ( P < .05) than intravenous milrinone. Inhaled milrinone prevented the alterations in relaxations of pulmonary arteries to acetylcholine caused by cardiopulmonary bypass, and relaxations to bradykinin were improved in the inhaled milrinone group ( P < .05) compared with the cardiopulmonary bypass and control groups.


CONCLUSIONS
Inhaled milrinone prevents the occurrence of the pulmonary endothelial dysfunction seen after cardiopulmonary bypass. The hemodynamic and oxygenation profiles obtained with inhaled milrinone are safer than with intravenous milrinone. These strategies might be useful in preventing pulmonary hypertension after cardiac surgery.
Lamarche
Y
Y
Research Center, and Department of Surgery, Montreal Heart Institute, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada. louis.perrault@icm-mhi.org
Malo
O
O
Thorin
E
E
Denault
A
A
Carrier
M
M
Roy
J
J
Perrault
L P
LP
D000109:Acetylcholine / Q000494:pharmacology; D000280:Administration, Inhalation; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002315:Cardiopulmonary Bypass; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D005260:Female; D006439:Hemodynamics; D007262:Infusions, Intravenous; D008297:Male; D020105:Milrinone / Q000008:administration & dosage*; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage*; D011651:Pulmonary Artery / Q000187:drug effects* / Q000503:physiopathology*; D013552:Swine
D010726:Phosphodiesterase Inhibitors; D020105:Milrinone; D000109:Acetylcholine; D001920:Bradykinin