Fluid balance in sheep lungs before and after extracorporeal perfusion.
Lung fluid balance was studied in sheep under the following conditions: 1) unanesthetized, standing in a metabolic cage; 2) anesthetized, in a supine position; 3) 1 h after extracorporeal perfusion; and 4) either 4-6 h after extracorporeal perfusion (i.e., control experiments) or 1.5 h after left atrial pressure was increased by 15 cmH2O. Lung lymph flow rate (QL), plasma and lymph concentrations for nine protein fractions, urea permeability-surface area product (PS), urea effective diffusivity (D1/2S), and extravascular lung water (VE) were measured under each condition. Bloodless wet and dry lung weights were measured at the end of each experiment. QL increased and lymph-to-plasma concentration ratio for total proteins (L/P) decreased after the sheep were anesthetized and placed in a supine position. This possibly resulted from an increase in microvascular pressure induced by anesthesia and/or reorientation of the lungs. PS, D1/2S, and VE decreased, indicating a decrease in perfused surface area associated with a decreased cardiac output or alteration in lung orientation. After 90 min of extracorporeal perfusion, no significant differences were found in QL, PS, and D1/2S compared with those measured during the anesthetized period. No changes in PS or D1/2S could be detected after an average of 4.2 h of extracorporeal perfusion. The average bloodless wet-to-dry lung weight ratio [(W-D)/D] was 3.77 +/- 0.12, well within the range for normal sheep lungs. An increase in venous pressure of 15 cmH2O produced a response similar to that observed in the unanesthetized sheep lung lymph preparation: QL increased, L/P decreased, PS and D1/2S did not increase, and VE and (W-D)/D increased slightly.(ABSTRACT TRUNCATED AT 250 WORDS)
Roselli
R J
RJ
Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, Tennessee 37235.
Parker
R E
RE
Riddle
W R
WR
Pou
N A
NA
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001834:Body Water / Q000502:physiology; D002199:Capillary Permeability / Q000502:physiology; D004058:Diffusion; D004591:Electrophoresis, Polyacrylamide Gel; D005112:Extracorporeal Circulation; D007457:Iodine Radioisotopes; D008168:Lung / Q000502:physiology*; D008196:Lymph / Q000502:physiology; D008198:Lymph Nodes / Q000502:physiology; D009929:Organ Size / Q000502:physiology; D010477:Perfusion; D012121:Respiration, Artificial; D012756:Sheep; D014882:Water-Electrolyte Balance / Q000502:physiology*
D007457:Iodine Radioisotopes