title: Pulmonary hemodynamics in neonatal lambs resuscitated with 21%, 50%, and 100% oxygen.
abstract: The effect of resuscitation with varying levels of O2 on pulmonary hemodynamics at birth is not well known. We hypothesized that the decrease in pulmonary vascular resistance (PVR) and subsequent response to pulmonary vasoconstrictors and vasodilators will differ following resuscitation with 21%, 50%, or 100% O2 for 30 min at birth in normal term lambs. Lambs at 141 d gestation were delivered by cesarean section and ventilated with 21% (21% Res; n=6), 50% (50% Res; n=6), or 100% 02 (100% Res; n=7) for 30 min followed by ventilation with 21% O2 in all three groups. A greater decrease in PVR was seen with 50% and 100% O2 ventilation than with 21% O2 (0.21 +/- 0.02, 0.21 +/- 0.02, and 0.34 +/- 0.05 mm Hg/mL/min/kg, respectively). Subsequent pulmonary vasoconstriction to hypoxia (10% O2) and the thromboxane,analog U46619 (0.5 and 1 mcirog/kg/min) was similar in all three groups. After inducing a stable elevation in PVR with U46619, impaired pulmonary vasodilation to inhaled NO (59 +/- 4, 65 +/- 4, and 74 +/- 5% of baseline PVR with 21, 50, and 100%Res, respectively) and acetylcholine infusion (67 +/- 8, 75 +/- 6, and 87 +/- 4% of baseline PVR with 21, 50, and 100%Res, respectively) and rebound pulmonary hypertension following their withdrawal were observed in the 100%Res group. We conclude that, while ventilation with 100% O2 at birth results in a greater initial decrease in PVR, subsequent pulmonary vasodilation to NO/acetylcholine is impaired.
authors.affiliation: Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York 14214, USA. slakshmi@buffalo.edu
authors.forename: Satyan
authors.initials: S
authors.lastname: Lakshminrusimha
authors.forename: James A
authors.initials: JA
authors.lastname: Russell
authors.forename: Robin H
authors.initials: RH
authors.lastname: Steinhorn
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Swartz
authors.forename: Rita M
authors.initials: RM
authors.lastname: Ryan
authors.forename: Sylvia F
authors.initials: SF
authors.lastname: Gugino
authors.forename: Karen A
authors.initials: KA
authors.lastname: Wynn
authors.forename: Vasanth H
authors.initials: VH
authors.lastname: Kumar
authors.forename: Bobby
authors.initials: B
authors.lastname: Mathew
authors.forename: Khaver
authors.initials: K
authors.lastname: Kirmani
authors.forename: Frederick C
authors.initials: FC
authors.lastname: Morin
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D005260:Female; D005865:Gestational Age; D006439:Hemodynamics; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology; D009569:Nitric Oxide / Q000008:administration & dosage / Q000378:metabolism; D010100:Oxygen / Q000008:administration & dosage* / Q000378:metabolism; D010102:Oxygen Inhalation Therapy; D011247:Pregnancy; D011659:Pulmonary Gas Exchange; D011897:Random Allocation; D012119:Respiration; D012151:Resuscitation; D034561:Sheep, Domestic; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine; D010100:Oxygen