title: Thoracic duct lymph flow in fetal sheep with increased venous pressure from electrically induced tachycardia.
abstract: The intent of this study was to investigate thoracic duct lymph flow, as it is related to the development of hydrops fetalis during rapid atrial pacing. We studied 6 fetal sheep at 128 +/- 6 days of gestation who had chronically placed thoracic duct catheters, aortic and superior vena cava catheters, and atrial pacing electrodes. Atrial pacing at 317 beats/min caused an elevation in central venous pressure from a baseline value of 3 Torr to 7 Torr without affecting pH, arterial blood gas tensions, aortic blood pressure, total protein concentration, or colloid osmotic pressure, although there was a small rise in hematocrit. The thoracic duct lymph flow rate at baseline was 41 +/- 6 ml/h. After atrial pacing for 6 h, the lymph flow rate as measured over at least three consecutive 10-min intervals, and presumably the transvascular fluid filtration rate, increased to 67 +/- 7 ml/h if it was collected at an outflow pressure of 3 Torr, equal to the venous pressure prior to the onset of atrial pacing. However, if the lymph was collected instead at an outflow pressure of 7 Torr, equal to the actual venous pressure measured with rapid atrial pacing, then the lymph flow rate diminished to 48 +/- 5 ml/h. This difference in lymph flow secondary to the increase in venous pressure could account for a maximum of 19 ml/h of edema that accumulates in fetal interstitium and body cavities with atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
authors.forename: A L
authors.initials: AL
authors.lastname: Gest
authors.forename: D K
authors.initials: DK
authors.lastname: Bair
authors.forename: M C
authors.initials: MC
authors.lastname: Vander Straten
mesh_terms: D000818:Animals; D002304:Cardiac Pacing, Artificial; D005333:Fetus / Q000502:physiology*; D006325:Heart Atria; D008196:Lymph / Q000502:physiology*; D012756:Sheep; D013610:Tachycardia / Q000209:etiology / Q000503:physiopathology*; D013897:Thoracic Duct / Q000196:embryology*; D014690:Venous Pressure