title: Retinal, choroidal and total ocular blood flow response to hypercarbia during spontaneous breathing and mechanical ventilation.
abstract: The effect of hypercarbia on ocular blood flow was studied in the newborn piglet with the isotope-labeled microsphere method. Blood flow measurements were made during spontaneous breathing and during paralyzation (pancuronium) and mechanical ventilation. Retinal blood flow increased from 0.40 +/- 0.07 (mean +/- SEM) ml/min/g at baseline levels to 0.91 +/- 0.17 ml/min/g at a PaCO2 level of 11.0 kPa during spontaneous ventilation. A similar response was observed during paralyzation and mechanical ventilation (0.89 +/- 0.15 ml/min/g at a PaCO2 of 11.1 kPa). For choroidal blood flow, however, the increase caused by hypercarbia during spontaneous ventilation (16.14 +/- 3.69 to 29.15 +/- 3.22 ml/min/g) was significantly reduced when the animals were paralyzed and mechanically ventilated (15.99 +/- 2.99 to 23.51 +/- 3.41 ml/min/g). Since choroidal blood flow accounts for 60-80% of oxygen delivery to the retina, paralyzation and mechanical ventilation may significantly reduce oxygen delivery to the retina during hypercarbia.
authors.affiliation: Department of Pediatric Research, Rikshospitalet, University of Oslo, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Stiris
authors.forename: C
authors.initials: C
authors.lastname: Hall
authors.forename: D
authors.initials: D
authors.lastname: Bratlid
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002829:Choroid / Q000098:blood supply*; D005123:Eye / Q000098:blood supply*; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D007231:Infant, Newborn; D009929:Organ Size; D010197:Pancuronium / Q000494:pharmacology; D010243:Paralysis / Q000139:chemically induced; D012039:Regional Blood Flow; D012119:Respiration; D012121:Respiration, Artificial; D012171:Retinal Vessels / Q000502:physiology*; D012178:Retinopathy of Prematurity / Q000517:prevention & control; D013552:Swine
chemical_list: D010197:Pancuronium