Effects of variable concentrations of inhaled nitric oxide and oxygen on the lungs of newborn piglets.
We previously demonstrated that inhalation of high concentrations of nitric oxide (iNO) and oxygen for 48 hr causes significant lung injury in newborn piglets. To determine if these effects persist at lower concentrations, groups of newborn piglets were mechanically ventilated for 48 hr with (study 1) constant O(2) (90-100%) and decreasing iNO (100-2 ppm) or (study 2) constant iNO (50 ppm) and decreasing O(2) (95-30%). Bronchoalveolar lavage (BAL) fluid was assayed for surfactant function, and markers of lung inflammation and physiologic parameters were monitored. Neutrophil chemotactic activity (NCA), % neutrophils, and total protein (TP) concentrations decreased significantly in BAL fluid of study 1 piglets as iNO was reduced and inhaled oxygen fraction remained constant, indicating less pulmonary injury at low iNO levels. Low-dose iNO (2 ppm) did not have antiinflammatory effects. However, surfactant function was minimally affected by lowering iNO, and was abnormal in all groups. In contrast, in study 2, pulmonary inflammation and injury were lower when O(2) was decreased to 70% or less, with iNO constant at 50 ppm. Surfactant function normalized and oxygenation improved in study 2 piglets when the inhaled oxygen fraction was decreased and iNO remained constant. These data suggest that iNO- and O(2)-induced lung injury may be minimized by weaning O(2) or iNO, although better physiologic function may be obtained when iNO concentrations are constant and O(2) is reduced. This has important implications in the clinical management of critically ill newborns treated with O(2) and iNO for pulmonary disorders.
Levine
Carolyn Robbins
CR
CardioPulmonary Research Institute, Winthrop-University Hospital, SUNY Stony Brook School of Medicine, Mineola, New York 11501, USA. clevine@winthrop.org
Kazzaz
Jeffrey A
JA
Koo
Hsi-Chi
HC
Chester
Darrin
D
Merritt
T Allen
TA
Matalon
Sadis
S
Pollack
Simcha
S
Davis
Jonathan M
JM
D000818:Animals; D000831:Animals, Newborn; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D001993:Bronchodilator Agents / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D006976:Hypertension, Pulmonary / Q000188:drug therapy; D008168:Lung / Q000187:drug effects* / Q000473:pathology; D009569:Nitric Oxide / Q000008:administration & dosage / Q000633:toxicity*; D010100:Oxygen / Q000008:administration & dosage / Q000633:toxicity*; D013552:Swine
D001993:Bronchodilator Agents; D009569:Nitric Oxide; D010100:Oxygen